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* Re: [PATCH v4 31/34] ima,evm: move initcalls to the LSM framework
From: Paul Moore @ 2025-09-30 20:11 UTC (permalink / raw)
  To: Mimi Zohar
  Cc: selinux, linux-integrity, linux-security-module, John Johansen,
	Roberto Sassu, Fan Wu, Mickaël Salaün,
	Günther Noack, Kees Cook, Micah Morton, Casey Schaufler,
	Tetsuo Handa, Nicolas Bouchinet, Xiu Jianfeng
In-Reply-To: <20250916220355.252592-67-paul@paul-moore.com>

On Tue, Sep 16, 2025 at 6:14 PM Paul Moore <paul@paul-moore.com> wrote:
>
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> This patch converts IMA and EVM to use the LSM frameworks's initcall
> mechanism. It moved the integrity_fs_init() call to ima_fs_init() and
> evm_init_secfs(), to work around the fact that there is no "integrity" LSM,
> and introduced integrity_fs_fini() to remove the integrity directory, if
> empty. Both integrity_fs_init() and integrity_fs_fini() support the
> scenario of being called by both the IMA and EVM LSMs.
>
> This patch does not touch any of the platform certificate code that
> lives under the security/integrity/platform_certs directory as the
> IMA/EVM developers would prefer to address that in a future patchset.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> [PM: adjust description as discussed over email]
> Signed-off-by: Paul Moore <paul@paul-moore.com>
> ---
>  security/integrity/evm/evm_main.c  |  3 +--
>  security/integrity/evm/evm_secfs.c | 11 +++++++++--
>  security/integrity/iint.c          | 14 ++++++++++++--
>  security/integrity/ima/ima_fs.c    | 11 +++++++++--
>  security/integrity/ima/ima_main.c  |  4 ++--
>  security/integrity/integrity.h     |  2 ++
>  6 files changed, 35 insertions(+), 10 deletions(-)

I appreciate you reviewing most (all?) of the other patches in this
patchset, but any chance you could review the IMA/EVM from Roberto?
This is the only patch that really needs your review ...

> diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
> index db8e324ed4e6..73d500a375cb 100644
> --- a/security/integrity/evm/evm_main.c
> +++ b/security/integrity/evm/evm_main.c
> @@ -1179,6 +1179,5 @@ DEFINE_LSM(evm) = {
>         .init = init_evm_lsm,
>         .order = LSM_ORDER_LAST,
>         .blobs = &evm_blob_sizes,
> +       .initcall_late = init_evm,
>  };
> -
> -late_initcall(init_evm);
> diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c
> index b0d2aad27850..c26724690cec 100644
> --- a/security/integrity/evm/evm_secfs.c
> +++ b/security/integrity/evm/evm_secfs.c
> @@ -302,10 +302,16 @@ int __init evm_init_secfs(void)
>         int error = 0;
>         struct dentry *dentry;
>
> -       evm_dir = securityfs_create_dir("evm", integrity_dir);
> -       if (IS_ERR(evm_dir))
> +       error = integrity_fs_init();
> +       if (error < 0)
>                 return -EFAULT;
>
> +       evm_dir = securityfs_create_dir("evm", integrity_dir);
> +       if (IS_ERR(evm_dir)) {
> +               error = -EFAULT;
> +               goto out;
> +       }
> +
>         dentry = securityfs_create_file("evm", 0660,
>                                       evm_dir, NULL, &evm_key_ops);
>         if (IS_ERR(dentry)) {
> @@ -329,5 +335,6 @@ int __init evm_init_secfs(void)
>  out:
>         securityfs_remove(evm_symlink);
>         securityfs_remove(evm_dir);
> +       integrity_fs_fini();
>         return error;
>  }
> diff --git a/security/integrity/iint.c b/security/integrity/iint.c
> index 068ac6c2ae1e..8ec1a3436a71 100644
> --- a/security/integrity/iint.c
> +++ b/security/integrity/iint.c
> @@ -42,8 +42,11 @@ void __init integrity_load_keys(void)
>                 evm_load_x509();
>  }
>
> -static int __init integrity_fs_init(void)
> +int __init integrity_fs_init(void)
>  {
> +       if (integrity_dir)
> +               return 0;
> +
>         integrity_dir = securityfs_create_dir("integrity", NULL);
>         if (IS_ERR(integrity_dir)) {
>                 int ret = PTR_ERR(integrity_dir);
> @@ -58,4 +61,11 @@ static int __init integrity_fs_init(void)
>         return 0;
>  }
>
> -late_initcall(integrity_fs_init)
> +void __init integrity_fs_fini(void)
> +{
> +       if (!integrity_dir || !simple_empty(integrity_dir))
> +               return;
> +
> +       securityfs_remove(integrity_dir);
> +       integrity_dir = NULL;
> +}
> diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
> index 87045b09f120..012a58959ff0 100644
> --- a/security/integrity/ima/ima_fs.c
> +++ b/security/integrity/ima/ima_fs.c
> @@ -499,9 +499,15 @@ int __init ima_fs_init(void)
>         struct dentry *dentry;
>         int ret;
>
> +       ret = integrity_fs_init();
> +       if (ret < 0)
> +               return ret;
> +
>         ima_dir = securityfs_create_dir("ima", integrity_dir);
> -       if (IS_ERR(ima_dir))
> -               return PTR_ERR(ima_dir);
> +       if (IS_ERR(ima_dir)) {
> +               ret = PTR_ERR(ima_dir);
> +               goto out;
> +       }
>
>         ima_symlink = securityfs_create_symlink("ima", NULL, "integrity/ima",
>                                                 NULL);
> @@ -555,6 +561,7 @@ int __init ima_fs_init(void)
>  out:
>         securityfs_remove(ima_symlink);
>         securityfs_remove(ima_dir);
> +       integrity_fs_fini();
>
>         return ret;
>  }
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index eade8e1e3cb1..b703bfc2f470 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -1283,6 +1283,6 @@ DEFINE_LSM(ima) = {
>         .init = init_ima_lsm,
>         .order = LSM_ORDER_LAST,
>         .blobs = &ima_blob_sizes,
> +       /* Start IMA after the TPM is available */
> +       .initcall_late = init_ima,
>  };
> -
> -late_initcall(init_ima);       /* Start IMA after the TPM is available */
> diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
> index c2c2da691123..7b388b66cf80 100644
> --- a/security/integrity/integrity.h
> +++ b/security/integrity/integrity.h
> @@ -114,6 +114,8 @@ struct ima_file_id {
>
>  int integrity_kernel_read(struct file *file, loff_t offset,
>                           void *addr, unsigned long count);
> +int __init integrity_fs_init(void);
> +void __init integrity_fs_fini(void);
>
>  #define INTEGRITY_KEYRING_EVM          0
>  #define INTEGRITY_KEYRING_IMA          1
> --
> 2.51.0

-- 
paul-moore.com

^ permalink raw reply

* Re: [PATCH] ima: Fall back to default kernel module signature verification
From: Mimi Zohar @ 2025-09-30 20:28 UTC (permalink / raw)
  To: Coiby Xu, linux-integrity
  Cc: Dmitry Torokhov, Karel Srot, Roberto Sassu, Dmitry Kasatkin,
	Eric Snowberg, Paul Moore, James Morris, Serge E. Hallyn,
	open list:SECURITY SUBSYSTEM, open list
In-Reply-To: <896f4fb0c0146512a66daf0b4c1e033aca4bd6d4.camel@linux.ibm.com>

On Tue, 2025-09-30 at 09:57 -0400, Mimi Zohar wrote:
> On Sun, 2025-09-28 at 11:03 +0800, Coiby Xu wrote:
> > Currently, for any IMA policy that requires appraisal for kernel modules
> > e.g. ima_policy=secure_boot, PowerPC architecture specific policy,
> > booting will fail because IMA will reject a kernel module which will
> > be decompressed in the kernel space and then have its signature
> > verified.
> > 
> > This happens because when in-kernel module decompression
> > (CONFIG_MODULE_DECOMPRESS) is enabled, kmod will use finit_module
> > syscall instead of init_module to load a module. And IMA mandates IMA
> > xattr verification for finit_module unless appraise_type=imasig|modsig
> > is specified in the rule.  However currently initramfs doesn't support
> > xattr. And IMA rule "func=MODULE_CHECK appraise_type=imasig|modsig"
> > doesn't work either because IMA will treat to-be-decompressed kernel
> > module as not having module signature as it can't decompress kernel
> > module to check if signature exists.
> > 
> > So fall back to default kernel module signature verification when we have
> > no way to verify IMA xattr.
> > 
> > Reported-by: Karel Srot <ksrot@redhat.com>
> > Signed-off-by: Coiby Xu <coxu@redhat.com>
> > ---
> > Another approach will be to make IMA decompress the kernel module to
> > check the signature. This requires refactoring kernel module code to
> > make the in-kernel module decompressing feature modular and seemingly
> > more efforts are needed. A second disadvantage is it feels
> > counter-intuitive to verify the same kernel module signature twice. And
> > we still need to make ima_policy=secure_boot allow verifying appended
> > module signature.
> > 
> > Anyways, I'm open to suggestions and can try the latter approach if
> > there are some benefits I'm not aware of or a better approach.
> 
> Coiby, there are multiple issues being discussed here.  Before deciding on an
> appropriate solution, let's frame the issues(s) properly.
> 
> 1. The finit_module syscall eventually calls init_module_from_file() to read the
> module into memory and then decompress it.  The problem is that the kernel
> module signature verification occurs during the kernel_read_file(), before the
> kernel module is decompressed.  Thus, the appended kernel module signature
> cannot be verified.
> 
> 2. CPIO doesn't have xattr support. There were multiple attempts at including
> xattrs in CPIO, but none were upstreamed [1].  If file signatures stored in
> security.ima were available in the initramfs, then finit_module() could verify
> them, as opposed to the appended kernel module signature.
> 
> 3. The issues described above are generic, not limited to Power.  When
> CONFIG_MODULE_SIG is configured, the arch specific IMA policy rules do not
> include an "appraise func=MODULE_CHECK".
> 
> 4. Unlike the arch specific IMA policy rules, the built-in secure boot IMA
> policy, specified on the boot command line as "ima_policy=secure_boot", always
> enforces the IMA signature stored in security.ima.
> 
> Partial solutions without kernel changes:
> - Enable CONFIG_MODULE_SIG  (Doesn't solve 4)
> - Disable kernel module compression.
> 
> Complete solution:
> - Pick up and upstream Roberto Sassu's last version of initramfs support [1].
> - Somehow prevent kernel_read_file() from failing when the kernel_read_file_id
> enumeration is READING_MODULE and the kernel module is compressed.  The change
> might be limited to ima_post_read_file().

or perhaps not totally.

init_module_from_file() doesn't pass the flags variable to kernel_read_file(). 
You might want to consider defining a new kernel_read_file_id enumeration named
READING_COMPRESSED_MODULE.

Mimi

> 
> [1] [PATCH v4 0/3] initramfs: add support for xattrs in the initial ram disk
> https://lore.kernel.org/linux-fsdevel/20190523121803.21638-1-roberto.sassu@huawei.com/
> 
> 


^ permalink raw reply

* [PATCH v4 0/9] tpm: Decouple Trenchboot dependencies
From: Jarkko Sakkinen @ 2025-09-30 22:16 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM, open list

Overview
========

Decouple TPM driver features relevant for Trenchboot and make tpm-buf
robust and decoupled entity from the rest of driver. By doing this, code
can be easily linked to the early boot code.

Goals and scope
===============

This patch set contains only changes, which are acceptable to mainline
driver without existence Trenchboot feature.

At the same the primary goal of the included is to make driver code 
robust enough to meet Trenchboot's requirements.

These constraints should define a meaningful DoD for this patch set.

v4:
- PCR patch has been removed because it does not fly without Trenchboot
  context.
v3:
- I think 6.19 is a better goal for this and thus expanded the series to
  be a generic Trenchboot enablers series. This version also consolidates
  my two separate ongoing series.
v2:
- While including fixes from v1, this patch set has a refocus in order to
  do minimal changes to make code base more compatible  Trenchboot.

Jarkko Sakkinen (9):
  tpm: Cap the number of PCR banks
  tpm: Use -EPERM as fallback error code in tpm_ret_to_err
  KEYS: trusted: Use tpm_ret_to_err() in trusted_tpm2
  tpm2-sessions: Remove 'attributes' from tpm_buf_append_auth
  tpm2-sessions: Unmask tpm_buf_append_hmac_session()
  KEYS: trusted: Open code tpm2_buf_append()
  tpm-buf: check for corruption in tpm_buf_append_handle()
  tpm-buf: Remove chip parameter from tpm_buf_append_handle
  tpm-buf: Enable managed and stack allocations.

 drivers/char/tpm/tpm-buf.c                | 141 ++++++----
 drivers/char/tpm/tpm-chip.c               |  13 +-
 drivers/char/tpm/tpm-sysfs.c              |  21 +-
 drivers/char/tpm/tpm.h                    |   2 -
 drivers/char/tpm/tpm1-cmd.c               | 185 +++++--------
 drivers/char/tpm/tpm2-cmd.c               | 313 ++++++++++------------
 drivers/char/tpm/tpm2-sessions.c          | 129 +++++----
 drivers/char/tpm/tpm2-space.c             |  44 ++-
 drivers/char/tpm/tpm_vtpm_proxy.c         |  30 +--
 include/linux/tpm.h                       |  65 ++---
 security/keys/trusted-keys/trusted_tpm1.c |  34 ++-
 security/keys/trusted-keys/trusted_tpm2.c | 237 +++++++---------
 12 files changed, 542 insertions(+), 672 deletions(-)

-- 
2.39.5


^ permalink raw reply

* [PATCH v4 1/9] tpm: Cap the number of PCR banks
From: Jarkko Sakkinen @ 2025-09-30 22:16 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Roberto Sassu,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, open list,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930221707.1373912-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

tpm2_get_pcr_allocation() does not cap any upper limit for the number of
banks. Cap the limit to four banks so that out of bounds values coming
from external I/O cause on only limited harm.

Cc: Roberto Sassu <roberto.sassu@huawei.com>
Fixes: bcfff8384f6c ("tpm: dynamically allocate the allocated_banks array")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
---
v4:
- Revert spurious changes from include/linux/tpm.h.
- Increase TPM2_MAX_BANKS to 8.
- Rename TPM2_MAX_BANKS as TPM2_MAX_PCR_BANKS for the sake of clarity.
v3:
- Wrote a more clear commit message.
- Fixed pr_err() message.
v2:
- A new patch.
---
 drivers/char/tpm/tpm-chip.c | 13 +++++++++----
 drivers/char/tpm/tpm.h      |  1 -
 drivers/char/tpm/tpm1-cmd.c | 25 -------------------------
 drivers/char/tpm/tpm2-cmd.c |  8 +++-----
 include/linux/tpm.h         |  8 +++++---
 5 files changed, 17 insertions(+), 38 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 687f6d8cd601..9a6538f76f50 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -559,14 +559,19 @@ static int tpm_add_hwrng(struct tpm_chip *chip)
 
 static int tpm_get_pcr_allocation(struct tpm_chip *chip)
 {
-	int rc;
+	int rc = 0;
 
 	if (tpm_is_firmware_upgrade(chip))
 		return 0;
 
-	rc = (chip->flags & TPM_CHIP_FLAG_TPM2) ?
-	     tpm2_get_pcr_allocation(chip) :
-	     tpm1_get_pcr_allocation(chip);
+	if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
+		chip->allocated_banks[0].alg_id = TPM_ALG_SHA1;
+		chip->allocated_banks[0].digest_size = hash_digest_size[HASH_ALGO_SHA1];
+		chip->allocated_banks[0].crypto_id = HASH_ALGO_SHA1;
+		chip->nr_allocated_banks = 1;
+	} else {
+		rc = tpm2_get_pcr_allocation(chip);
+	}
 
 	if (rc > 0)
 		return -ENODEV;
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 57ef8589f5f5..769fa6b00c54 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -252,7 +252,6 @@ int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf);
 ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 		    const char *desc, size_t min_cap_length);
 int tpm1_get_random(struct tpm_chip *chip, u8 *out, size_t max);
-int tpm1_get_pcr_allocation(struct tpm_chip *chip);
 unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
 int tpm_pm_suspend(struct device *dev);
 int tpm_pm_resume(struct device *dev);
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index cf64c7385105..5c49bdff33de 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -786,28 +786,3 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 
 	return rc;
 }
-
-/**
- * tpm1_get_pcr_allocation() - initialize the allocated bank
- * @chip: TPM chip to use.
- *
- * The function initializes the SHA1 allocated bank to extend PCR
- *
- * Return:
- * * 0 on success,
- * * < 0 on error.
- */
-int tpm1_get_pcr_allocation(struct tpm_chip *chip)
-{
-	chip->allocated_banks = kcalloc(1, sizeof(*chip->allocated_banks),
-					GFP_KERNEL);
-	if (!chip->allocated_banks)
-		return -ENOMEM;
-
-	chip->allocated_banks[0].alg_id = TPM_ALG_SHA1;
-	chip->allocated_banks[0].digest_size = hash_digest_size[HASH_ALGO_SHA1];
-	chip->allocated_banks[0].crypto_id = HASH_ALGO_SHA1;
-	chip->nr_allocated_banks = 1;
-
-	return 0;
-}
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 7d77f6fbc152..97501c567c34 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -538,11 +538,9 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 
 	nr_possible_banks = be32_to_cpup(
 		(__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
-
-	chip->allocated_banks = kcalloc(nr_possible_banks,
-					sizeof(*chip->allocated_banks),
-					GFP_KERNEL);
-	if (!chip->allocated_banks) {
+	if (nr_possible_banks > TPM2_MAX_PCR_BANKS) {
+		pr_err("tpm: unexpected number of banks: %u > %u",
+		       nr_possible_banks, TPM2_MAX_PCR_BANKS);
 		rc = -ENOMEM;
 		goto out;
 	}
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 900c81a2bc41..f998dca4ea07 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -27,7 +27,9 @@
 #include <crypto/aes.h>
 
 #define TPM_DIGEST_SIZE 20	/* Max TPM v1.2 PCR size */
-#define TPM_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE
+
+#define TPM2_MAX_DIGEST_SIZE	SHA512_DIGEST_SIZE
+#define TPM2_MAX_PCR_BANKS	8
 
 struct tpm_chip;
 struct trusted_key_payload;
@@ -69,7 +71,7 @@ enum tpm2_curves {
 
 struct tpm_digest {
 	u16 alg_id;
-	u8 digest[TPM_MAX_DIGEST_SIZE];
+	u8 digest[TPM2_MAX_DIGEST_SIZE];
 } __packed;
 
 struct tpm_bank_info {
@@ -190,7 +192,7 @@ struct tpm_chip {
 	unsigned int groups_cnt;
 
 	u32 nr_allocated_banks;
-	struct tpm_bank_info *allocated_banks;
+	struct tpm_bank_info allocated_banks[TPM2_MAX_PCR_BANKS];
 #ifdef CONFIG_ACPI
 	acpi_handle acpi_dev_handle;
 	char ppi_version[TPM_PPI_VERSION_LEN + 1];
-- 
2.39.5


^ permalink raw reply related

* [PATCH v4 2/9] tpm: Use -EPERM as fallback error code in tpm_ret_to_err
From: Jarkko Sakkinen @ 2025-09-30 22:17 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Stefano Garzarella,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, open list,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930221707.1373912-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Using -EFAULT as the tpm_ret_to_err() fallback error code causes makes it
incompatible on how trusted keys transmute TPM return codes.

Change the fallback as -EPERM in order to gain compatibility with trusted
keys. In addition, map TPM_RC_HASH to -EINVAL in order to be compatible
with tpm2_seal_trusted() return values.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
---
v4:
- No changes.
v3:
- Removed fixes tag as it hardly categorizes as a bug fix.
v2:
- Split trusted_tpm2 change to a separate patch.
---
 include/linux/tpm.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index f998dca4ea07..dff558140c69 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -457,8 +457,10 @@ static inline ssize_t tpm_ret_to_err(ssize_t ret)
 		return 0;
 	case TPM2_RC_SESSION_MEMORY:
 		return -ENOMEM;
+	case TPM2_RC_HASH:
+		return -EINVAL;
 	default:
-		return -EFAULT;
+		return -EPERM;
 	}
 }
 
-- 
2.39.5


^ permalink raw reply related

* [PATCH v4 3/9] KEYS: trusted: Use tpm_ret_to_err() in trusted_tpm2
From: Jarkko Sakkinen @ 2025-09-30 22:17 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Stefano Garzarella,
	David Howells, Jarkko Sakkinen, Paul Moore, James Morris,
	Serge E. Hallyn, James Bottomley, Mimi Zohar,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM, open list
In-Reply-To: <20250930221707.1373912-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Use tpm_ret_to_err() to transmute TPM return codes in trusted_tpm2.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
---
v4:
- No changes.
v3:
- No changes.
v2:
- New patch split out from the fix.
---
 security/keys/trusted-keys/trusted_tpm2.c | 26 ++++++-----------------
 1 file changed, 7 insertions(+), 19 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 024be262702f..e165b117bbca 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -348,25 +348,19 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	}
 
 	blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
+	if (blob_len < 0)
+		rc = blob_len;
 
 out:
 	tpm_buf_destroy(&sized);
 	tpm_buf_destroy(&buf);
 
-	if (rc > 0) {
-		if (tpm2_rc_value(rc) == TPM2_RC_HASH)
-			rc = -EINVAL;
-		else
-			rc = -EPERM;
-	}
-	if (blob_len < 0)
-		rc = blob_len;
-	else
+	if (!rc)
 		payload->blob_len = blob_len;
 
 out_put:
 	tpm_put_ops(chip);
-	return rc;
+	return tpm_ret_to_err(rc);
 }
 
 /**
@@ -468,10 +462,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 		kfree(blob);
 	tpm_buf_destroy(&buf);
 
-	if (rc > 0)
-		rc = -EPERM;
-
-	return rc;
+	return tpm_ret_to_err(rc);
 }
 
 /**
@@ -534,8 +525,6 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 	tpm_buf_fill_hmac_session(chip, &buf);
 	rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
 	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
-	if (rc > 0)
-		rc = -EPERM;
 
 	if (!rc) {
 		data_len = be16_to_cpup(
@@ -568,7 +557,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 
 out:
 	tpm_buf_destroy(&buf);
-	return rc;
+	return tpm_ret_to_err(rc);
 }
 
 /**
@@ -600,6 +589,5 @@ int tpm2_unseal_trusted(struct tpm_chip *chip,
 
 out:
 	tpm_put_ops(chip);
-
-	return rc;
+	return tpm_ret_to_err(rc);
 }
-- 
2.39.5


^ permalink raw reply related

* [PATCH v4 4/9] tpm2-sessions: Remove 'attributes' from tpm_buf_append_auth
From: Jarkko Sakkinen @ 2025-09-30 22:17 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Jonathan McDowell,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, Roberto Sassu,
	Mimi Zohar, open list, open list:KEYS/KEYRINGS,
	open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930221707.1373912-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

In a previous bug fix, 'attributes' was added by mistake to
tpm_buf_append_auth(). Remove the parameter.

Fixes: 27184f8905ba ("tpm: Opt-in in disable PCR integrity protection")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
---
v4:
- No changes.
v3:
- No changes
v2:
- Uncorrupt the patch.
---
 drivers/char/tpm/tpm2-cmd.c      | 2 +-
 drivers/char/tpm/tpm2-sessions.c | 5 ++---
 include/linux/tpm.h              | 2 +-
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 97501c567c34..bf8294e3d8f2 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -191,7 +191,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 		tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0);
 	} else {
 		tpm_buf_append_handle(chip, &buf, pcr_idx);
-		tpm_buf_append_auth(chip, &buf, 0, NULL, 0);
+		tpm_buf_append_auth(chip, &buf, NULL, 0);
 	}
 
 	tpm_buf_append_u32(&buf, chip->nr_allocated_banks);
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 6d03c224e6b2..13f019d1312a 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -266,7 +266,7 @@ void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
 EXPORT_SYMBOL_GPL(tpm_buf_append_name);
 
 void tpm_buf_append_auth(struct tpm_chip *chip, struct tpm_buf *buf,
-			 u8 attributes, u8 *passphrase, int passphrase_len)
+			 u8 *passphrase, int passphrase_len)
 {
 	/* offset tells us where the sessions area begins */
 	int offset = buf->handles * 4 + TPM_HEADER_SIZE;
@@ -327,8 +327,7 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf,
 #endif
 
 	if (!tpm2_chip_auth(chip)) {
-		tpm_buf_append_auth(chip, buf, attributes, passphrase,
-				    passphrase_len);
+		tpm_buf_append_auth(chip, buf, passphrase, passphrase_len);
 		return;
 	}
 
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index dff558140c69..5b44222a36c4 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -535,7 +535,7 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf,
 				 u8 attributes, u8 *passphrase,
 				 int passphraselen);
 void tpm_buf_append_auth(struct tpm_chip *chip, struct tpm_buf *buf,
-			 u8 attributes, u8 *passphrase, int passphraselen);
+			 u8 *passphrase, int passphraselen);
 static inline void tpm_buf_append_hmac_session_opt(struct tpm_chip *chip,
 						   struct tpm_buf *buf,
 						   u8 attributes,
-- 
2.39.5


^ permalink raw reply related

* [PATCH v4 5/9] tpm2-sessions: Unmask tpm_buf_append_hmac_session()
From: Jarkko Sakkinen @ 2025-09-30 22:17 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Jonathan McDowell,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, James Bottomley,
	Mimi Zohar, open list, open list:KEYS/KEYRINGS,
	open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930221707.1373912-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Open code tpm_buf_append_hmac_session_opt() in order to unmask the code
paths in the call sites of tpm_buf_append_hmac_session().

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
---
v4:
- Fixed typo in short summary.
v3:
- No changes.
v2:
- Uncorrupt the patch.
---
 drivers/char/tpm/tpm2-cmd.c               | 14 +++++++++++---
 include/linux/tpm.h                       | 23 -----------------------
 security/keys/trusted-keys/trusted_tpm2.c | 12 ++++++++++--
 3 files changed, 21 insertions(+), 28 deletions(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index bf8294e3d8f2..254003e5dd8b 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -257,9 +257,17 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 
 	do {
 		tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
-		tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT
-						| TPM2_SA_CONTINUE_SESSION,
-						NULL, 0);
+		if (tpm2_chip_auth(chip)) {
+			tpm_buf_append_hmac_session(chip, &buf,
+						    TPM2_SA_ENCRYPT |
+						    TPM2_SA_CONTINUE_SESSION,
+						    NULL, 0);
+		} else  {
+			offset = buf.handles * 4 + TPM_HEADER_SIZE;
+			head = (struct tpm_header *)buf.data;
+			if (tpm_buf_length(&buf) == offset)
+				head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
+		}
 		tpm_buf_append_u16(&buf, num_bytes);
 		tpm_buf_fill_hmac_session(chip, &buf);
 		err = tpm_transmit_cmd(chip, &buf,
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 5b44222a36c4..e3c65d33e041 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -536,29 +536,6 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf,
 				 int passphraselen);
 void tpm_buf_append_auth(struct tpm_chip *chip, struct tpm_buf *buf,
 			 u8 *passphrase, int passphraselen);
-static inline void tpm_buf_append_hmac_session_opt(struct tpm_chip *chip,
-						   struct tpm_buf *buf,
-						   u8 attributes,
-						   u8 *passphrase,
-						   int passphraselen)
-{
-	struct tpm_header *head;
-	int offset;
-
-	if (tpm2_chip_auth(chip)) {
-		tpm_buf_append_hmac_session(chip, buf, attributes, passphrase, passphraselen);
-	} else  {
-		offset = buf->handles * 4 + TPM_HEADER_SIZE;
-		head = (struct tpm_header *)buf->data;
-
-		/*
-		 * If the only sessions are optional, the command tag must change to
-		 * TPM2_ST_NO_SESSIONS.
-		 */
-		if (tpm_buf_length(buf) == offset)
-			head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
-	}
-}
 
 #ifdef CONFIG_TCG_TPM2_HMAC
 
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index e165b117bbca..c414a7006d78 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -482,8 +482,10 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 			   struct trusted_key_options *options,
 			   u32 blob_handle)
 {
+	struct tpm_header *head;
 	struct tpm_buf buf;
 	u16 data_len;
+	int offset;
 	u8 *data;
 	int rc;
 
@@ -518,8 +520,14 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		tpm2_buf_append_auth(&buf, options->policyhandle,
 				     NULL /* nonce */, 0, 0,
 				     options->blobauth, options->blobauth_len);
-		tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT,
-						NULL, 0);
+		if (tpm2_chip_auth(chip)) {
+			tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, NULL, 0);
+		} else  {
+			offset = buf.handles * 4 + TPM_HEADER_SIZE;
+			head = (struct tpm_header *)buf.data;
+			if (tpm_buf_length(&buf) == offset)
+				head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
+		}
 	}
 
 	tpm_buf_fill_hmac_session(chip, &buf);
-- 
2.39.5


^ permalink raw reply related

* [PATCH v4 6/9] KEYS: trusted: Open code tpm2_buf_append()
From: Jarkko Sakkinen @ 2025-09-30 22:17 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Jonathan McDowell,
	David Howells, Jarkko Sakkinen, Paul Moore, James Morris,
	Serge E. Hallyn, James Bottomley, Mimi Zohar,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM, open list
In-Reply-To: <20250930221707.1373912-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

tpm2_buf_append_auth() has only single call site and most of its parameters
are redundant. Open code it to the call site. Remove illegit FIXME comment
as there is no categorized bug and replace it with more sane comment about
implementation (i.e. "non-opionated inline comment").

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Jonathan McDowell <noodles@earth.li>
---
v4:
- No changes:
v3:
- No changes.
v2:
- No changes.
---
 security/keys/trusted-keys/trusted_tpm2.c | 51 ++++-------------------
 1 file changed, 9 insertions(+), 42 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index c414a7006d78..8e3b283a59b2 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -198,36 +198,6 @@ int tpm2_key_priv(void *context, size_t hdrlen,
 	return 0;
 }
 
-/**
- * tpm2_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer.
- *
- * @buf: an allocated tpm_buf instance
- * @session_handle: session handle
- * @nonce: the session nonce, may be NULL if not used
- * @nonce_len: the session nonce length, may be 0 if not used
- * @attributes: the session attributes
- * @hmac: the session HMAC or password, may be NULL if not used
- * @hmac_len: the session HMAC or password length, maybe 0 if not used
- */
-static void tpm2_buf_append_auth(struct tpm_buf *buf, u32 session_handle,
-				 const u8 *nonce, u16 nonce_len,
-				 u8 attributes,
-				 const u8 *hmac, u16 hmac_len)
-{
-	tpm_buf_append_u32(buf, 9 + nonce_len + hmac_len);
-	tpm_buf_append_u32(buf, session_handle);
-	tpm_buf_append_u16(buf, nonce_len);
-
-	if (nonce && nonce_len)
-		tpm_buf_append(buf, nonce, nonce_len);
-
-	tpm_buf_append_u8(buf, attributes);
-	tpm_buf_append_u16(buf, hmac_len);
-
-	if (hmac && hmac_len)
-		tpm_buf_append(buf, hmac, hmac_len);
-}
-
 /**
  * tpm2_seal_trusted() - seal the payload of a trusted key
  *
@@ -507,19 +477,16 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 					    options->blobauth_len);
 	} else {
 		/*
-		 * FIXME: The policy session was generated outside the
-		 * kernel so we don't known the nonce and thus can't
-		 * calculate a HMAC on it.  Therefore, the user can
-		 * only really use TPM2_PolicyPassword and we must
-		 * send down the plain text password, which could be
-		 * intercepted.  We can still encrypt the returned
-		 * key, but that's small comfort since the interposer
-		 * could repeat our actions with the exfiltrated
-		 * password.
+		 * The policy session is generated outside the kernel, and thus
+		 * the password will end up being unencrypted on the bus, as
+		 * HMAC nonce cannot be calculated for it.
 		 */
-		tpm2_buf_append_auth(&buf, options->policyhandle,
-				     NULL /* nonce */, 0, 0,
-				     options->blobauth, options->blobauth_len);
+		tpm_buf_append_u32(&buf, 9 + options->blobauth_len);
+		tpm_buf_append_u32(&buf, options->policyhandle);
+		tpm_buf_append_u16(&buf, 0);
+		tpm_buf_append_u8(&buf, 0);
+		tpm_buf_append_u16(&buf, options->blobauth_len);
+		tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
 		if (tpm2_chip_auth(chip)) {
 			tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, NULL, 0);
 		} else  {
-- 
2.39.5


^ permalink raw reply related

* [PATCH v4 7/9] tpm-buf: check for corruption in tpm_buf_append_handle()
From: Jarkko Sakkinen @ 2025-09-30 22:17 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Jonathan McDowell,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, James Bottomley,
	Mimi Zohar, open list, open list:KEYS/KEYRINGS,
	open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930221707.1373912-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Unify TPM_BUF_BOUNDARY_ERROR and TPM_BUF_OVERFLOW into TPM_BUF_INVALID
flag because semantically they are identical.

Test and set TPM_BUF_INVALID in tpm_buf_append_handle() following the
pattern from other functions in tpm-buf.c.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
---
v4:
- No changes.
v3:
- No changes.
v2:
- A new patch.
---
 drivers/char/tpm/tpm-buf.c                | 14 ++++++++------
 include/linux/tpm.h                       |  8 +++-----
 security/keys/trusted-keys/trusted_tpm2.c |  6 +++---
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index dc882fc9fa9e..69ee77400539 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -104,13 +104,12 @@ EXPORT_SYMBOL_GPL(tpm_buf_length);
  */
 void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
 {
-	/* Return silently if overflow has already happened. */
-	if (buf->flags & TPM_BUF_OVERFLOW)
+	if (buf->flags & TPM_BUF_INVALID)
 		return;
 
 	if ((buf->length + new_length) > PAGE_SIZE) {
 		WARN(1, "tpm_buf: write overflow\n");
-		buf->flags |= TPM_BUF_OVERFLOW;
+		buf->flags |= TPM_BUF_INVALID;
 		return;
 	}
 
@@ -157,8 +156,12 @@ EXPORT_SYMBOL_GPL(tpm_buf_append_u32);
  */
 void tpm_buf_append_handle(struct tpm_chip *chip, struct tpm_buf *buf, u32 handle)
 {
+	if (buf->flags & TPM_BUF_INVALID)
+		return;
+
 	if (buf->flags & TPM_BUF_TPM2B) {
 		dev_err(&chip->dev, "Invalid buffer type (TPM2B)\n");
+		buf->flags |= TPM_BUF_INVALID;
 		return;
 	}
 
@@ -177,14 +180,13 @@ static void tpm_buf_read(struct tpm_buf *buf, off_t *offset, size_t count, void
 {
 	off_t next_offset;
 
-	/* Return silently if overflow has already happened. */
-	if (buf->flags & TPM_BUF_BOUNDARY_ERROR)
+	if (buf->flags & TPM_BUF_INVALID)
 		return;
 
 	next_offset = *offset + count;
 	if (next_offset > buf->length) {
 		WARN(1, "tpm_buf: read out of boundary\n");
-		buf->flags |= TPM_BUF_BOUNDARY_ERROR;
+		buf->flags |= TPM_BUF_INVALID;
 		return;
 	}
 
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index e3c65d33e041..4613216e9d95 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -370,12 +370,10 @@ struct tpm_header {
 } __packed;
 
 enum tpm_buf_flags {
-	/* the capacity exceeded: */
-	TPM_BUF_OVERFLOW	= BIT(0),
 	/* TPM2B format: */
-	TPM_BUF_TPM2B		= BIT(1),
-	/* read out of boundary: */
-	TPM_BUF_BOUNDARY_ERROR	= BIT(2),
+	TPM_BUF_TPM2B		= BIT(0),
+	/* The buffer is in invalid and unusable state: */
+	TPM_BUF_INVALID		= BIT(1),
 };
 
 /*
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 8e3b283a59b2..119d5152c0db 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -295,7 +295,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	/* creation PCR */
 	tpm_buf_append_u32(&buf, 0);
 
-	if (buf.flags & TPM_BUF_OVERFLOW) {
+	if (buf.flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		tpm2_end_auth_session(chip);
 		goto out;
@@ -308,7 +308,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		goto out;
 
 	blob_len = tpm_buf_read_u32(&buf, &offset);
-	if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_BOUNDARY_ERROR) {
+	if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		goto out;
 	}
@@ -414,7 +414,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 
 	tpm_buf_append(&buf, blob, blob_len);
 
-	if (buf.flags & TPM_BUF_OVERFLOW) {
+	if (buf.flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		tpm2_end_auth_session(chip);
 		goto out;
-- 
2.39.5


^ permalink raw reply related

* [PATCH v4 8/9] tpm-buf: Remove chip parameter from tpm_buf_append_handle
From: Jarkko Sakkinen @ 2025-09-30 22:17 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Jonathan McDowell,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, open list,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930221707.1373912-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Remove chip parameter from tpm_buf_append_handle() in order to maintain
decoupled state with tpm-buf. This is mandatory change in order to re-use
the module in early boot code of Trenchboot, and the binding itself brings
no benefit. Use WARN like in other functions, as the error condition can
happen only as a net effect of a trivial programming mistake.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
---
v4:
- No changes.
v3:
- No changes.
v2:
- No changes.
---
 drivers/char/tpm/tpm-buf.c       | 5 ++---
 drivers/char/tpm/tpm2-cmd.c      | 2 +-
 drivers/char/tpm/tpm2-sessions.c | 2 +-
 include/linux/tpm.h              | 2 +-
 4 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index 69ee77400539..1b9dee0d0681 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -147,20 +147,19 @@ EXPORT_SYMBOL_GPL(tpm_buf_append_u32);
 
 /**
  * tpm_buf_append_handle() - Add a handle
- * @chip:	&tpm_chip instance
  * @buf:	&tpm_buf instance
  * @handle:	a TPM object handle
  *
  * Add a handle to the buffer, and increase the count tracking the number of
  * handles in the command buffer. Works only for command buffers.
  */
-void tpm_buf_append_handle(struct tpm_chip *chip, struct tpm_buf *buf, u32 handle)
+void tpm_buf_append_handle(struct tpm_buf *buf, u32 handle)
 {
 	if (buf->flags & TPM_BUF_INVALID)
 		return;
 
 	if (buf->flags & TPM_BUF_TPM2B) {
-		dev_err(&chip->dev, "Invalid buffer type (TPM2B)\n");
+		WARN(1, "tpm-buf: invalid type: TPM2B\n");
 		buf->flags |= TPM_BUF_INVALID;
 		return;
 	}
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 254003e5dd8b..e548b0ac7654 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -190,7 +190,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 		tpm_buf_append_name(chip, &buf, pcr_idx, NULL);
 		tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0);
 	} else {
-		tpm_buf_append_handle(chip, &buf, pcr_idx);
+		tpm_buf_append_handle(&buf, pcr_idx);
 		tpm_buf_append_auth(chip, &buf, NULL, 0);
 	}
 
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 13f019d1312a..bbc05f0997a8 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -232,7 +232,7 @@ void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
 #endif
 
 	if (!tpm2_chip_auth(chip)) {
-		tpm_buf_append_handle(chip, buf, handle);
+		tpm_buf_append_handle(buf, handle);
 		return;
 	}
 
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 4613216e9d95..e86c22b30153 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -427,7 +427,7 @@ void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value);
 u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset);
 u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset);
 u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset);
-void tpm_buf_append_handle(struct tpm_chip *chip, struct tpm_buf *buf, u32 handle);
+void tpm_buf_append_handle(struct tpm_buf *buf, u32 handle);
 
 /*
  * Check if TPM device is in the firmware upgrade mode.
-- 
2.39.5


^ permalink raw reply related

* [PATCH v4 9/9] tpm-buf: Enable managed and stack allocations.
From: Jarkko Sakkinen @ 2025-09-30 22:17 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Stefan Berger,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, James Bottomley,
	Mimi Zohar, open list, open list:KEYS/KEYRINGS,
	open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930221707.1373912-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Decouple kzalloc from buffer creation, so that  a managed allocation can be
done trivially:

	struct tpm_buf *buf __free(kfree) buf = kzalloc(TPM_BUFSIZE,
							GFP_KERNEL);
	if (!buf)
		return -ENOMEM;
	tpm_buf_init(buf, TPM_BUFSIZE);

Alternatively, stack allocations are also possible:

	u8 buf_data[512];
	struct tpm_buf *buf = (struct tpm_buf *)buf_data;
	tpm_buf_init(buf, sizeof(buf_data));

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
---
v4:
- Since every single tpm_transmit_cmd() call site needs to be
  changed anyhow, use 'dest' parameter more structured and
  actually useful way, and pick the string TCG 1.2 and 2.0
  specifications.
- tpm1-cmd: Remove useless rc declarations and repliace them
  with trivial "return tpm_transmit_cmd" statement.
- Reverted spurious changes in include/linux/tpm.h.
- Use concisely TPM_BUFSIZE instead of PAGE_SIZE.
v3:
- A new patch from the earlier series with more scoped changes and
  less abstract commit message.
---
 drivers/char/tpm/tpm-buf.c                | 122 +++++----
 drivers/char/tpm/tpm-sysfs.c              |  21 +-
 drivers/char/tpm/tpm.h                    |   1 -
 drivers/char/tpm/tpm1-cmd.c               | 162 +++++-------
 drivers/char/tpm/tpm2-cmd.c               | 299 ++++++++++------------
 drivers/char/tpm/tpm2-sessions.c          | 122 +++++----
 drivers/char/tpm/tpm2-space.c             |  44 ++--
 drivers/char/tpm/tpm_vtpm_proxy.c         |  30 +--
 include/linux/tpm.h                       |  18 +-
 security/keys/trusted-keys/trusted_tpm1.c |  34 ++-
 security/keys/trusted-keys/trusted_tpm2.c | 176 ++++++-------
 11 files changed, 486 insertions(+), 543 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index 1b9dee0d0681..a3bf3c3d0c48 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -7,82 +7,109 @@
 #include <linux/module.h>
 #include <linux/tpm.h>
 
-/**
- * tpm_buf_init() - Allocate and initialize a TPM command
- * @buf:	A &tpm_buf
- * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
- * @ordinal:	A command ordinal
- *
- * Return: 0 or -ENOMEM
- */
-int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
+static void __tpm_buf_size_invariant(struct tpm_buf *buf, u16 buf_size)
 {
-	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
-	if (!buf->data)
-		return -ENOMEM;
-
-	tpm_buf_reset(buf, tag, ordinal);
-	return 0;
+	u32 buf_size_2 = (u32)buf->capacity + (u32)sizeof(*buf);
+
+	if (!buf->capacity) {
+		if (buf_size > TPM_BUFSIZE) {
+			WARN(1, "%s: size overflow: %u\n", __func__, buf_size);
+			buf->flags |= TPM_BUF_INVALID;
+		}
+	} else {
+		if (buf_size != buf_size_2) {
+			WARN(1, "%s: size mismatch: %u != %u\n", __func__, buf_size,
+			     buf_size_2);
+			buf->flags |= TPM_BUF_INVALID;
+		}
+	}
 }
-EXPORT_SYMBOL_GPL(tpm_buf_init);
 
-/**
- * tpm_buf_reset() - Initialize a TPM command
- * @buf:	A &tpm_buf
- * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
- * @ordinal:	A command ordinal
- */
-void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
+static void __tpm_buf_reset(struct tpm_buf *buf, u16 buf_size, u16 tag, u32 ordinal)
 {
 	struct tpm_header *head = (struct tpm_header *)buf->data;
 
+	__tpm_buf_size_invariant(buf, buf_size);
+
+	if (buf->flags & TPM_BUF_INVALID)
+		return;
+
 	WARN_ON(tag != TPM_TAG_RQU_COMMAND && tag != TPM2_ST_NO_SESSIONS &&
 		tag != TPM2_ST_SESSIONS && tag != 0);
 
 	buf->flags = 0;
 	buf->length = sizeof(*head);
+	buf->capacity = buf_size - sizeof(*buf);
+	buf->handles = 0;
 	head->tag = cpu_to_be16(tag);
 	head->length = cpu_to_be32(sizeof(*head));
 	head->ordinal = cpu_to_be32(ordinal);
+}
+
+static void __tpm_buf_reset_sized(struct tpm_buf *buf, u16 buf_size)
+{
+	__tpm_buf_size_invariant(buf, buf_size);
+
+	if (buf->flags & TPM_BUF_INVALID)
+		return;
+
+	buf->flags = TPM_BUF_TPM2B;
+	buf->length = 2;
+	buf->capacity = buf_size - sizeof(*buf);
 	buf->handles = 0;
+	buf->data[0] = 0;
+	buf->data[1] = 0;
 }
-EXPORT_SYMBOL_GPL(tpm_buf_reset);
 
 /**
- * tpm_buf_init_sized() - Allocate and initialize a sized (TPM2B) buffer
- * @buf:	A @tpm_buf
- *
- * Return: 0 or -ENOMEM
+ * tpm_buf_init() - Initialize a TPM command
+ * @buf:	A &tpm_buf
+ * @buf_size:	Size of the buffer.
  */
-int tpm_buf_init_sized(struct tpm_buf *buf)
+void tpm_buf_init(struct tpm_buf *buf, u16 buf_size)
 {
-	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
-	if (!buf->data)
-		return -ENOMEM;
+	memset(buf, 0, buf_size);
+	__tpm_buf_reset(buf, buf_size, TPM_TAG_RQU_COMMAND, 0);
+}
+EXPORT_SYMBOL_GPL(tpm_buf_init);
 
-	tpm_buf_reset_sized(buf);
-	return 0;
+/**
+ * tpm_buf_init_sized() - Initialize a sized buffer
+ * @buf:	A &tpm_buf
+ * @buf_size:	Size of the buffer.
+ */
+void tpm_buf_init_sized(struct tpm_buf *buf, u16 buf_size)
+{
+	memset(buf, 0, buf_size);
+	__tpm_buf_reset_sized(buf, buf_size);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_init_sized);
 
 /**
- * tpm_buf_reset_sized() - Initialize a sized buffer
+ * tpm_buf_reset() - Re-initialize a TPM command
  * @buf:	A &tpm_buf
+ * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
+ * @ordinal:	A command ordinal
  */
-void tpm_buf_reset_sized(struct tpm_buf *buf)
+void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
 {
-	buf->flags = TPM_BUF_TPM2B;
-	buf->length = 2;
-	buf->data[0] = 0;
-	buf->data[1] = 0;
+	u16 buf_size = buf->capacity + sizeof(*buf);
+
+	__tpm_buf_reset(buf, buf_size, tag, ordinal);
 }
-EXPORT_SYMBOL_GPL(tpm_buf_reset_sized);
+EXPORT_SYMBOL_GPL(tpm_buf_reset);
 
-void tpm_buf_destroy(struct tpm_buf *buf)
+/**
+ * tpm_buf_reset_sized() - Re-initialize a sized buffer
+ * @buf:	A &tpm_buf
+ */
+void tpm_buf_reset_sized(struct tpm_buf *buf)
 {
-	free_page((unsigned long)buf->data);
+	u16 buf_size = buf->capacity + sizeof(*buf);
+
+	__tpm_buf_reset_sized(buf, buf_size);
 }
-EXPORT_SYMBOL_GPL(tpm_buf_destroy);
+EXPORT_SYMBOL_GPL(tpm_buf_reset_sized);
 
 /**
  * tpm_buf_length() - Return the number of bytes consumed by the data
@@ -92,6 +119,9 @@ EXPORT_SYMBOL_GPL(tpm_buf_destroy);
  */
 u32 tpm_buf_length(struct tpm_buf *buf)
 {
+	if (buf->flags & TPM_BUF_INVALID)
+		return 0;
+
 	return buf->length;
 }
 EXPORT_SYMBOL_GPL(tpm_buf_length);
@@ -104,10 +134,12 @@ EXPORT_SYMBOL_GPL(tpm_buf_length);
  */
 void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
 {
+	u32 total_length = (u32)buf->length + (u32)new_length;
+
 	if (buf->flags & TPM_BUF_INVALID)
 		return;
 
-	if ((buf->length + new_length) > PAGE_SIZE) {
+	if (total_length > (u32)buf->capacity) {
 		WARN(1, "tpm_buf: write overflow\n");
 		buf->flags |= TPM_BUF_INVALID;
 		return;
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 94231f052ea7..f5dcadb1ab3c 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -32,28 +32,29 @@ struct tpm_readpubek_out {
 static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 			  char *buf)
 {
-	struct tpm_buf tpm_buf;
 	struct tpm_readpubek_out *out;
 	int i;
 	char *str = buf;
 	struct tpm_chip *chip = to_tpm_chip(dev);
 	char anti_replay[20];
 
+	struct tpm_buf *tpm_buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!tpm_buf)
+		return -ENOMEM;
+
 	memset(&anti_replay, 0, sizeof(anti_replay));
 
 	if (tpm_try_get_ops(chip))
 		return 0;
 
-	if (tpm_buf_init(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK))
-		goto out_ops;
-
-	tpm_buf_append(&tpm_buf, anti_replay, sizeof(anti_replay));
+	tpm_buf_init(tpm_buf, TPM_BUFSIZE);
+	tpm_buf_reset(tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK);
+	tpm_buf_append(tpm_buf, anti_replay, sizeof(anti_replay));
 
-	if (tpm_transmit_cmd(chip, &tpm_buf, READ_PUBEK_RESULT_MIN_BODY_SIZE,
-			     "attempting to read the PUBEK"))
-		goto out_buf;
+	if (tpm_transmit_cmd(chip, tpm_buf, READ_PUBEK_RESULT_MIN_BODY_SIZE, "TPM_ReadPubek"))
+		goto out_ops;
 
-	out = (struct tpm_readpubek_out *)&tpm_buf.data[10];
+	out = (struct tpm_readpubek_out *)&tpm_buf->data[10];
 	str +=
 	    sprintf(str,
 		    "Algorithm: %4ph\n"
@@ -71,8 +72,6 @@ static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 	for (i = 0; i < 256; i += 16)
 		str += sprintf(str, "%16ph\n", &out->modulus[i]);
 
-out_buf:
-	tpm_buf_destroy(&tpm_buf);
 out_ops:
 	tpm_put_ops(chip);
 	return str - buf;
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 769fa6b00c54..eaff2055b541 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -32,7 +32,6 @@
 #endif
 
 #define TPM_MINOR		224	/* officially assigned */
-#define TPM_BUFSIZE		4096
 #define TPM_NUM_DEVICES		65536
 #define TPM_RETRY		50
 
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 5c49bdff33de..10cb5d008c9f 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -323,20 +323,14 @@ unsigned long tpm1_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
  */
 static int tpm1_startup(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	dev_info(&chip->dev, "starting up the TPM manually\n");
-
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
-	if (rc < 0)
-		return rc;
-
-	tpm_buf_append_u16(&buf, TPM_ST_CLEAR);
-
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to start the TPM");
-	tpm_buf_destroy(&buf);
-	return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
+	tpm_buf_append_u16(buf, TPM_ST_CLEAR);
+	return tpm_transmit_cmd(chip, buf, 0, "TPM_Startup");
 }
 
 int tpm1_get_timeouts(struct tpm_chip *chip)
@@ -463,50 +457,45 @@ int tpm1_get_timeouts(struct tpm_chip *chip)
 int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash,
 		    const char *log_msg)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_EXTEND);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, pcr_idx);
-	tpm_buf_append(&buf, hash, TPM_DIGEST_SIZE);
-
-	rc = tpm_transmit_cmd(chip, &buf, TPM_DIGEST_SIZE, log_msg);
-	tpm_buf_destroy(&buf);
-	return rc;
+	tpm_buf_append_u32(buf, pcr_idx);
+	tpm_buf_append(buf, hash, TPM_DIGEST_SIZE);
+	return tpm_transmit_cmd(chip, buf, TPM_DIGEST_SIZE, log_msg);
 }
 
 #define TPM_ORD_GET_CAP 101
 ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 		    const char *desc, size_t min_cap_length)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
 
 	if (subcap_id == TPM_CAP_VERSION_1_1 ||
 	    subcap_id == TPM_CAP_VERSION_1_2) {
-		tpm_buf_append_u32(&buf, subcap_id);
-		tpm_buf_append_u32(&buf, 0);
+		tpm_buf_append_u32(buf, subcap_id);
+		tpm_buf_append_u32(buf, 0);
 	} else {
 		if (subcap_id == TPM_CAP_FLAG_PERM ||
 		    subcap_id == TPM_CAP_FLAG_VOL)
-			tpm_buf_append_u32(&buf, TPM_CAP_FLAG);
+			tpm_buf_append_u32(buf, TPM_CAP_FLAG);
 		else
-			tpm_buf_append_u32(&buf, TPM_CAP_PROP);
+			tpm_buf_append_u32(buf, TPM_CAP_PROP);
 
-		tpm_buf_append_u32(&buf, 4);
-		tpm_buf_append_u32(&buf, subcap_id);
+		tpm_buf_append_u32(buf, 4);
+		tpm_buf_append_u32(buf, subcap_id);
 	}
-	rc = tpm_transmit_cmd(chip, &buf, min_cap_length, desc);
+	rc = tpm_transmit_cmd(chip, buf, min_cap_length, desc);
 	if (!rc)
-		*cap = *(cap_t *)&buf.data[TPM_HEADER_SIZE + 4];
-	tpm_buf_destroy(&buf);
+		*cap = *(cap_t *)&buf->data[TPM_HEADER_SIZE + 4];
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm1_getcap);
@@ -531,81 +520,69 @@ int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 {
 	struct tpm1_get_random_out *out;
 	u32 num_bytes =  min_t(u32, max, TPM_MAX_RNG_DATA);
-	struct tpm_buf buf;
 	u32 total = 0;
 	int retries = 5;
 	u32 recd;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
+	tpm_buf_init(buf, TPM_BUFSIZE);
 	do {
-		tpm_buf_append_u32(&buf, num_bytes);
+		tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
+		tpm_buf_append_u32(buf, num_bytes);
 
-		rc = tpm_transmit_cmd(chip, &buf, sizeof(out->rng_data_len),
-				      "attempting get random");
+		rc = tpm_transmit_cmd(chip, buf, sizeof(out->rng_data_len), "TPM_GetRandom");
 		if (rc) {
 			if (rc > 0)
 				rc = -EIO;
-			goto out;
+			return rc;
 		}
 
-		out = (struct tpm1_get_random_out *)&buf.data[TPM_HEADER_SIZE];
+		out = (struct tpm1_get_random_out *)&buf->data[TPM_HEADER_SIZE];
 
 		recd = be32_to_cpu(out->rng_data_len);
-		if (recd > num_bytes) {
-			rc = -EFAULT;
-			goto out;
-		}
+		if (recd > num_bytes)
+			return -EFAULT;
+
+		if (buf->length < TPM_HEADER_SIZE +
+				  sizeof(out->rng_data_len) + recd)
+			return -EFAULT;
 
-		if (tpm_buf_length(&buf) < TPM_HEADER_SIZE +
-					   sizeof(out->rng_data_len) + recd) {
-			rc = -EFAULT;
-			goto out;
-		}
 		memcpy(dest, out->rng_data, recd);
 
 		dest += recd;
 		total += recd;
 		num_bytes -= recd;
-
-		tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
 	} while (retries-- && total < max);
 
 	rc = total ? (int)total : -EIO;
-out:
-	tpm_buf_destroy(&buf);
 	return rc;
 }
 
 #define TPM_ORD_PCRREAD 21
 int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCRREAD);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, pcr_idx);
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCRREAD);
+	tpm_buf_append_u32(buf, pcr_idx);
 
-	rc = tpm_transmit_cmd(chip, &buf, TPM_DIGEST_SIZE,
-			      "attempting to read a pcr value");
+	rc = tpm_transmit_cmd(chip, buf, TPM_DIGEST_SIZE, "TPM_PCRRead");
 	if (rc)
-		goto out;
-
-	if (tpm_buf_length(&buf) < TPM_DIGEST_SIZE) {
-		rc = -EFAULT;
-		goto out;
-	}
+		return rc;
 
-	memcpy(res_buf, &buf.data[TPM_HEADER_SIZE], TPM_DIGEST_SIZE);
+	if (buf->length < TPM_DIGEST_SIZE)
+		return -EFAULT;
 
-out:
-	tpm_buf_destroy(&buf);
+	memcpy(res_buf, &buf->data[TPM_HEADER_SIZE], TPM_DIGEST_SIZE);
 	return rc;
 }
 
@@ -619,16 +596,13 @@ int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
  */
 static int tpm1_continue_selftest(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_CONTINUE_SELFTEST);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	rc = tpm_transmit_cmd(chip, &buf, 0, "continue selftest");
-	tpm_buf_destroy(&buf);
-	return rc;
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_CONTINUE_SELFTEST);
+	return tpm_transmit_cmd(chip, buf, 0, "TPM_ContinueSelfTest");
 }
 
 /**
@@ -742,22 +716,24 @@ int tpm1_auto_startup(struct tpm_chip *chip)
 int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 {
 	u8 dummy_hash[TPM_DIGEST_SIZE] = { 0 };
-	struct tpm_buf buf;
 	unsigned int try;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
 	/* for buggy tpm, flush pcrs with extend to selected dummy */
 	if (tpm_suspend_pcr)
 		rc = tpm1_pcr_extend(chip, tpm_suspend_pcr, dummy_hash,
 				     "extending dummy pcr before suspend");
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
-	if (rc)
-		return rc;
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
+
 	/* now do the actual savestate */
 	for (try = 0; try < TPM_RETRY; try++) {
-		rc = tpm_transmit_cmd(chip, &buf, 0, NULL);
+		rc = tpm_transmit_cmd(chip, buf, 0, NULL);
 		/*
 		 * If the TPM indicates that it is too busy to respond to
 		 * this command then retry before giving up.  It can take
@@ -772,7 +748,7 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 			break;
 		tpm_msleep(TPM_TIMEOUT_RETRY);
 
-		tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
+		tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
 	}
 
 	if (rc)
@@ -782,7 +758,5 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 		dev_warn(&chip->dev, "TPM savestate took %dms\n",
 			 try * TPM_TIMEOUT_RETRY);
 
-	tpm_buf_destroy(&buf);
-
 	return rc;
 }
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index e548b0ac7654..768719bbbf04 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -104,12 +104,15 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 {
 	int i;
 	int rc;
-	struct tpm_buf buf;
 	struct tpm2_pcr_read_out *out;
 	u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
 	u16 digest_size;
 	u16 expected_digest_size = 0;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	if (pcr_idx >= TPM2_PLATFORM_PCR)
 		return -EINVAL;
 
@@ -124,36 +127,31 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 		expected_digest_size = chip->allocated_banks[i].digest_size;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
-	if (rc)
-		return rc;
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
 
 	pcr_select[pcr_idx >> 3] = 1 << (pcr_idx & 0x7);
 
-	tpm_buf_append_u32(&buf, 1);
-	tpm_buf_append_u16(&buf, digest->alg_id);
-	tpm_buf_append_u8(&buf, TPM2_PCR_SELECT_MIN);
-	tpm_buf_append(&buf, (const unsigned char *)pcr_select,
+	tpm_buf_append_u32(buf, 1);
+	tpm_buf_append_u16(buf, digest->alg_id);
+	tpm_buf_append_u8(buf, TPM2_PCR_SELECT_MIN);
+	tpm_buf_append(buf, (const unsigned char *)pcr_select,
 		       sizeof(pcr_select));
 
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to read a pcr value");
+	rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_PCR_Read");
 	if (rc)
-		goto out;
+		return rc;
 
-	out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
+	out = (struct tpm2_pcr_read_out *)&buf->data[TPM_HEADER_SIZE];
 	digest_size = be16_to_cpu(out->digest_size);
 	if (digest_size > sizeof(digest->digest) ||
-	    (!digest_size_ptr && digest_size != expected_digest_size)) {
-		rc = -EINVAL;
-		goto out;
-	}
+	    (!digest_size_ptr && digest_size != expected_digest_size))
+		return rc;
 
 	if (digest_size_ptr)
 		*digest_size_ptr = digest_size;
 
 	memcpy(digest->digest, out->digest, digest_size);
-out:
-	tpm_buf_destroy(&buf);
 	return rc;
 }
 
@@ -169,46 +167,45 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 		    struct tpm_digest *digests)
 {
-	struct tpm_buf buf;
 	int rc;
 	int i;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	if (!disable_pcr_integrity) {
 		rc = tpm2_start_auth_session(chip);
 		if (rc)
 			return rc;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
-	if (rc) {
-		if (!disable_pcr_integrity)
-			tpm2_end_auth_session(chip);
-		return rc;
-	}
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
 
 	if (!disable_pcr_integrity) {
-		tpm_buf_append_name(chip, &buf, pcr_idx, NULL);
-		tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0);
+		tpm_buf_append_name(chip, buf, pcr_idx, NULL);
+		tpm_buf_append_hmac_session(chip, buf, 0, NULL, 0);
 	} else {
-		tpm_buf_append_handle(&buf, pcr_idx);
-		tpm_buf_append_auth(chip, &buf, NULL, 0);
+		tpm_buf_append_handle(buf, pcr_idx);
+		tpm_buf_append_auth(chip, buf, NULL, 0);
 	}
 
-	tpm_buf_append_u32(&buf, chip->nr_allocated_banks);
+	tpm_buf_append_u32(buf, chip->nr_allocated_banks);
 
 	for (i = 0; i < chip->nr_allocated_banks; i++) {
-		tpm_buf_append_u16(&buf, digests[i].alg_id);
-		tpm_buf_append(&buf, (const unsigned char *)&digests[i].digest,
+		tpm_buf_append_u16(buf, digests[i].alg_id);
+		tpm_buf_append(buf, (const unsigned char *)&digests[i].digest,
 			       chip->allocated_banks[i].digest_size);
 	}
+	if (buf->flags & TPM_BUF_INVALID)
+		return -EINVAL;
 
 	if (!disable_pcr_integrity)
-		tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting extend a PCR value");
+		tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_PCR_Extend");
 	if (!disable_pcr_integrity)
-		rc = tpm_buf_check_hmac_response(chip, &buf, rc);
-
-	tpm_buf_destroy(&buf);
+		rc = tpm_buf_check_hmac_response(chip, buf, rc);
 
 	return rc;
 }
@@ -233,7 +230,6 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 {
 	struct tpm2_get_random_out *out;
 	struct tpm_header *head;
-	struct tpm_buf buf;
 	u32 recd;
 	u32 num_bytes = max;
 	int err;
@@ -245,51 +241,50 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 	if (!num_bytes || max > TPM_MAX_RNG_DATA)
 		return -EINVAL;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	err = tpm2_start_auth_session(chip);
 	if (err)
 		return err;
 
-	err = tpm_buf_init(&buf, 0, 0);
-	if (err) {
-		tpm2_end_auth_session(chip);
-		return err;
-	}
-
+	tpm_buf_init(buf, TPM_BUFSIZE);
 	do {
-		tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
+		tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
 		if (tpm2_chip_auth(chip)) {
-			tpm_buf_append_hmac_session(chip, &buf,
+			tpm_buf_append_hmac_session(chip, buf,
 						    TPM2_SA_ENCRYPT |
 						    TPM2_SA_CONTINUE_SESSION,
 						    NULL, 0);
 		} else  {
-			offset = buf.handles * 4 + TPM_HEADER_SIZE;
-			head = (struct tpm_header *)buf.data;
-			if (tpm_buf_length(&buf) == offset)
+			offset = buf->handles * 4 + TPM_HEADER_SIZE;
+			head = (struct tpm_header *)buf->data;
+			if (tpm_buf_length(buf) == offset)
 				head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
 		}
-		tpm_buf_append_u16(&buf, num_bytes);
-		tpm_buf_fill_hmac_session(chip, &buf);
-		err = tpm_transmit_cmd(chip, &buf,
+		tpm_buf_append_u16(buf, num_bytes);
+		tpm_buf_fill_hmac_session(chip, buf);
+		err = tpm_transmit_cmd(chip, buf,
 				       offsetof(struct tpm2_get_random_out,
 						buffer),
-				       "attempting get random");
-		err = tpm_buf_check_hmac_response(chip, &buf, err);
+				       "TPM2_GetRandom");
+		err = tpm_buf_check_hmac_response(chip, buf, err);
 		if (err) {
 			if (err > 0)
 				err = -EIO;
 			goto out;
 		}
 
-		head = (struct tpm_header *)buf.data;
+		head = (struct tpm_header *)buf->data;
 		offset = TPM_HEADER_SIZE;
 		/* Skip the parameter size field: */
 		if (be16_to_cpu(head->tag) == TPM2_ST_SESSIONS)
 			offset += 4;
 
-		out = (struct tpm2_get_random_out *)&buf.data[offset];
+		out = (struct tpm2_get_random_out *)&buf->data[offset];
 		recd = min_t(u32, be16_to_cpu(out->size), num_bytes);
-		if (tpm_buf_length(&buf) <
+		if (tpm_buf_length(buf) <
 		    TPM_HEADER_SIZE +
 		    offsetof(struct tpm2_get_random_out, buffer) +
 		    recd) {
@@ -303,11 +298,9 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 		num_bytes -= recd;
 	} while (retries-- && total < max);
 
-	tpm_buf_destroy(&buf);
-
 	return total ? total : -EIO;
+
 out:
-	tpm_buf_destroy(&buf);
 	tpm2_end_auth_session(chip);
 	return err;
 }
@@ -319,20 +312,18 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
  */
 void tpm2_flush_context(struct tpm_chip *chip, u32 handle)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_FLUSH_CONTEXT);
-	if (rc) {
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf) {
 		dev_warn(&chip->dev, "0x%08x was not flushed, out of memory\n",
 			 handle);
 		return;
 	}
 
-	tpm_buf_append_u32(&buf, handle);
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_FLUSH_CONTEXT);
+	tpm_buf_append_u32(buf, handle);
 
-	tpm_transmit_cmd(chip, &buf, 0, "flushing context");
-	tpm_buf_destroy(&buf);
+	tpm_transmit_cmd(chip, buf, 0, "TPM2_FlushContext");
 }
 EXPORT_SYMBOL_GPL(tpm2_flush_context);
 
@@ -359,19 +350,20 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
 			const char *desc)
 {
 	struct tpm2_get_cap_out *out;
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		return rc;
-	tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
-	tpm_buf_append_u32(&buf, property_id);
-	tpm_buf_append_u32(&buf, 1);
-	rc = tpm_transmit_cmd(chip, &buf, 0, NULL);
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_TPM_PROPERTIES);
+	tpm_buf_append_u32(buf, property_id);
+	tpm_buf_append_u32(buf, 1);
+	rc = tpm_transmit_cmd(chip, buf, 0, NULL);
 	if (!rc) {
-		out = (struct tpm2_get_cap_out *)
-			&buf.data[TPM_HEADER_SIZE];
+		out = (struct tpm2_get_cap_out *)&buf->data[TPM_HEADER_SIZE];
 		/*
 		 * To prevent failing boot up of some systems, Infineon TPM2.0
 		 * returns SUCCESS on TPM2_Startup in field upgrade mode. Also
@@ -383,7 +375,6 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
 		else
 			rc = -ENODATA;
 	}
-	tpm_buf_destroy(&buf);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm2_get_tpm_pt);
@@ -400,15 +391,14 @@ EXPORT_SYMBOL_GPL(tpm2_get_tpm_pt);
  */
 void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SHUTDOWN);
-	if (rc)
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
 		return;
-	tpm_buf_append_u16(&buf, shutdown_type);
-	tpm_transmit_cmd(chip, &buf, 0, "stopping the TPM");
-	tpm_buf_destroy(&buf);
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SHUTDOWN);
+	tpm_buf_append_u16(buf, shutdown_type);
+	tpm_transmit_cmd(chip, buf, 0, "TPM2_Shutdown");
 }
 
 /**
@@ -426,20 +416,19 @@ void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type)
  */
 static int tpm2_do_selftest(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
 	int full;
 	int rc;
 
-	for (full = 0; full < 2; full++) {
-		rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
-		if (rc)
-			return rc;
-
-		tpm_buf_append_u8(&buf, full);
-		rc = tpm_transmit_cmd(chip, &buf, 0,
-				      "attempting the self test");
-		tpm_buf_destroy(&buf);
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
+	for (full = 0; full < 2; full++) {
+		tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
+		tpm_buf_append_u8(buf, full);
+		rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_SelfTest");
 		if (rc == TPM2_RC_TESTING)
 			rc = TPM2_RC_SUCCESS;
 		if (rc == TPM2_RC_INITIALIZE || rc == TPM2_RC_SUCCESS)
@@ -464,23 +453,24 @@ static int tpm2_do_selftest(struct tpm_chip *chip)
 int tpm2_probe(struct tpm_chip *chip)
 {
 	struct tpm_header *out;
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		return rc;
-	tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
-	tpm_buf_append_u32(&buf, TPM_PT_TOTAL_COMMANDS);
-	tpm_buf_append_u32(&buf, 1);
-	rc = tpm_transmit_cmd(chip, &buf, 0, NULL);
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_TPM_PROPERTIES);
+	tpm_buf_append_u32(buf, TPM_PT_TOTAL_COMMANDS);
+	tpm_buf_append_u32(buf, 1);
+	rc = tpm_transmit_cmd(chip, buf, 0, NULL);
 	/* We ignore TPM return codes on purpose. */
 	if (rc >=  0) {
-		out = (struct tpm_header *)buf.data;
+		out = (struct tpm_header *)buf->data;
 		if (be16_to_cpu(out->tag) == TPM2_ST_NO_SESSIONS)
 			chip->flags |= TPM_CHIP_FLAG_TPM2;
 	}
-	tpm_buf_destroy(&buf);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tpm2_probe);
@@ -520,7 +510,6 @@ struct tpm2_pcr_selection {
 ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 {
 	struct tpm2_pcr_selection pcr_selection;
-	struct tpm_buf buf;
 	void *marker;
 	void *end;
 	void *pcr_select_offset;
@@ -532,39 +521,37 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	int rc;
 	int i = 0;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, TPM2_CAP_PCRS);
-	tpm_buf_append_u32(&buf, 0);
-	tpm_buf_append_u32(&buf, 1);
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_PCRS);
+	tpm_buf_append_u32(buf, 0);
+	tpm_buf_append_u32(buf, 1);
 
-	rc = tpm_transmit_cmd(chip, &buf, 9, "get tpm pcr allocation");
+	rc = tpm_transmit_cmd(chip, buf, 9, "TPM2_GetCapability(PCRS)");
 	if (rc)
-		goto out;
+		return rc;
 
-	nr_possible_banks = be32_to_cpup(
-		(__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
+	nr_possible_banks = be32_to_cpup((__be32 *)&buf->data[TPM_HEADER_SIZE + 5]);
 	if (nr_possible_banks > TPM2_MAX_PCR_BANKS) {
 		pr_err("tpm: unexpected number of banks: %u > %u",
 		       nr_possible_banks, TPM2_MAX_PCR_BANKS);
-		rc = -ENOMEM;
-		goto out;
+		return -ENOMEM;
 	}
 
-	marker = &buf.data[TPM_HEADER_SIZE + 9];
+	marker = &buf->data[TPM_HEADER_SIZE + 9];
 
-	rsp_len = be32_to_cpup((__be32 *)&buf.data[2]);
-	end = &buf.data[rsp_len];
+	rsp_len = be32_to_cpup((__be32 *)&buf->data[2]);
+	end = &buf->data[rsp_len];
 
 	for (i = 0; i < nr_possible_banks; i++) {
 		pcr_select_offset = marker +
 			offsetof(struct tpm2_pcr_selection, size_of_select);
-		if (pcr_select_offset >= end) {
-			rc = -EFAULT;
-			break;
-		}
+		if (pcr_select_offset >= end)
+			return -EFAULT;
 
 		memcpy(&pcr_selection, marker, sizeof(pcr_selection));
 		hash_alg = be16_to_cpu(pcr_selection.hash_alg);
@@ -576,7 +563,7 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 
 			rc = tpm2_init_bank_info(chip, nr_alloc_banks);
 			if (rc < 0)
-				break;
+				return rc;
 
 			nr_alloc_banks++;
 		}
@@ -588,21 +575,21 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	}
 
 	chip->nr_allocated_banks = nr_alloc_banks;
-out:
-	tpm_buf_destroy(&buf);
-
-	return rc;
+	return 0;
 }
 
 int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
 	u32 nr_commands;
 	__be32 *attrs;
 	u32 cc;
 	int i;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	rc = tpm2_get_tpm_pt(chip, TPM_PT_TOTAL_COMMANDS, &nr_commands, NULL);
 	if (rc)
 		goto out;
@@ -619,30 +606,24 @@ int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 		goto out;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		goto out;
-
-	tpm_buf_append_u32(&buf, TPM2_CAP_COMMANDS);
-	tpm_buf_append_u32(&buf, TPM2_CC_FIRST);
-	tpm_buf_append_u32(&buf, nr_commands);
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_COMMANDS);
+	tpm_buf_append_u32(buf, TPM2_CC_FIRST);
+	tpm_buf_append_u32(buf, nr_commands);
 
-	rc = tpm_transmit_cmd(chip, &buf, 9 + 4 * nr_commands, NULL);
-	if (rc) {
-		tpm_buf_destroy(&buf);
+	rc = tpm_transmit_cmd(chip, buf, 9 + 4 * nr_commands, NULL);
+	if (rc)
 		goto out;
-	}
 
-	if (nr_commands !=
-	    be32_to_cpup((__be32 *)&buf.data[TPM_HEADER_SIZE + 5])) {
+	if (nr_commands != be32_to_cpup((__be32 *)&buf->data[TPM_HEADER_SIZE + 5])) {
 		rc = -EFAULT;
-		tpm_buf_destroy(&buf);
 		goto out;
 	}
 
 	chip->nr_commands = nr_commands;
 
-	attrs = (__be32 *)&buf.data[TPM_HEADER_SIZE + 9];
+	attrs = (__be32 *)&buf->data[TPM_HEADER_SIZE + 9];
 	for (i = 0; i < nr_commands; i++, attrs++) {
 		chip->cc_attrs_tbl[i] = be32_to_cpup(attrs);
 		cc = chip->cc_attrs_tbl[i] & 0xFFFF;
@@ -654,8 +635,6 @@ int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 		}
 	}
 
-	tpm_buf_destroy(&buf);
-
 out:
 	if (rc > 0)
 		rc = -ENODEV;
@@ -676,20 +655,14 @@ EXPORT_SYMBOL_GPL(tpm2_get_cc_attrs_tbl);
 
 static int tpm2_startup(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	dev_info(&chip->dev, "starting up the TPM manually\n");
-
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_STARTUP);
-	if (rc < 0)
-		return rc;
-
-	tpm_buf_append_u16(&buf, TPM2_SU_CLEAR);
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to start the TPM");
-	tpm_buf_destroy(&buf);
-
-	return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_STARTUP);
+	tpm_buf_append_u16(buf, TPM2_SU_CLEAR);
+	return tpm_transmit_cmd(chip, buf, 0, "TPM2_Startup");
 }
 
 /**
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index bbc05f0997a8..378b8d21b10c 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -182,19 +182,18 @@ static int tpm2_parse_read_public(char *name, struct tpm_buf *buf)
 
 static int tpm2_read_public(struct tpm_chip *chip, u32 handle, char *name)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, handle);
-	rc = tpm_transmit_cmd(chip, &buf, 0, "read public");
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
+	tpm_buf_append_u32(buf, handle);
+	rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_ReadPublic");
 	if (rc == TPM2_RC_SUCCESS)
-		rc = tpm2_parse_read_public(name, &buf);
-
-	tpm_buf_destroy(&buf);
+		rc = tpm2_parse_read_public(name, buf);
 
 	return rc;
 }
@@ -924,7 +923,6 @@ static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key)
 int tpm2_start_auth_session(struct tpm_chip *chip)
 {
 	struct tpm2_auth *auth;
-	struct tpm_buf buf;
 	u32 null_key;
 	int rc;
 
@@ -933,6 +931,10 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
 		return 0;
 	}
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	auth = kzalloc(sizeof(*auth), GFP_KERNEL);
 	if (!auth)
 		return -ENOMEM;
@@ -943,41 +945,37 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
 
 	auth->session = TPM_HEADER_SIZE;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_START_AUTH_SESS);
-	if (rc)
-		goto out;
-
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_START_AUTH_SESS);
 	/* salt key handle */
-	tpm_buf_append_u32(&buf, null_key);
+	tpm_buf_append_u32(buf, null_key);
 	/* bind key handle */
-	tpm_buf_append_u32(&buf, TPM2_RH_NULL);
+	tpm_buf_append_u32(buf, TPM2_RH_NULL);
 	/* nonce caller */
 	get_random_bytes(auth->our_nonce, sizeof(auth->our_nonce));
-	tpm_buf_append_u16(&buf, sizeof(auth->our_nonce));
-	tpm_buf_append(&buf, auth->our_nonce, sizeof(auth->our_nonce));
+	tpm_buf_append_u16(buf, sizeof(auth->our_nonce));
+	tpm_buf_append(buf, auth->our_nonce, sizeof(auth->our_nonce));
 
 	/* append encrypted salt and squirrel away unencrypted in auth */
-	tpm_buf_append_salt(&buf, chip, auth);
+	tpm_buf_append_salt(buf, chip, auth);
 	/* session type (HMAC, audit or policy) */
-	tpm_buf_append_u8(&buf, TPM2_SE_HMAC);
+	tpm_buf_append_u8(buf, TPM2_SE_HMAC);
 
 	/* symmetric encryption parameters */
 	/* symmetric algorithm */
-	tpm_buf_append_u16(&buf, TPM_ALG_AES);
+	tpm_buf_append_u16(buf, TPM_ALG_AES);
 	/* bits for symmetric algorithm */
-	tpm_buf_append_u16(&buf, AES_KEY_BITS);
+	tpm_buf_append_u16(buf, AES_KEY_BITS);
 	/* symmetric algorithm mode (must be CFB) */
-	tpm_buf_append_u16(&buf, TPM_ALG_CFB);
+	tpm_buf_append_u16(buf, TPM_ALG_CFB);
 	/* hash algorithm for session */
-	tpm_buf_append_u16(&buf, TPM_ALG_SHA256);
+	tpm_buf_append_u16(buf, TPM_ALG_SHA256);
 
-	rc = tpm_ret_to_err(tpm_transmit_cmd(chip, &buf, 0, "StartAuthSession"));
+	rc = tpm_ret_to_err(tpm_transmit_cmd(chip, buf, 0, "TPM2_StartAuthSession"));
 	tpm2_flush_context(chip, null_key);
 
 	if (rc == TPM2_RC_SUCCESS)
-		rc = tpm2_parse_start_auth_session(auth, &buf);
-
-	tpm_buf_destroy(&buf);
+		rc = tpm2_parse_start_auth_session(auth, buf);
 
 	if (rc == TPM2_RC_SUCCESS) {
 		chip->auth = auth;
@@ -1199,18 +1197,18 @@ static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy,
 			       u32 *handle, u8 *name)
 {
 	int rc;
-	struct tpm_buf buf;
-	struct tpm_buf template;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE_PRIMARY);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	rc = tpm_buf_init_sized(&template);
-	if (rc) {
-		tpm_buf_destroy(&buf);
-		return rc;
-	}
+	struct tpm_buf *template __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!template)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE_PRIMARY);
+	tpm_buf_init_sized(template, TPM_BUFSIZE);
 
 	/*
 	 * create the template.  Note: in order for userspace to
@@ -1222,75 +1220,71 @@ static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy,
 	 */
 
 	/* key type */
-	tpm_buf_append_u16(&template, TPM_ALG_ECC);
+	tpm_buf_append_u16(template, TPM_ALG_ECC);
 
 	/* name algorithm */
-	tpm_buf_append_u16(&template, TPM_ALG_SHA256);
+	tpm_buf_append_u16(template, TPM_ALG_SHA256);
 
 	/* object properties */
-	tpm_buf_append_u32(&template, TPM2_OA_NULL_KEY);
+	tpm_buf_append_u32(template, TPM2_OA_NULL_KEY);
 
 	/* sauth policy (empty) */
-	tpm_buf_append_u16(&template, 0);
+	tpm_buf_append_u16(template, 0);
 
 	/* BEGIN parameters: key specific; for ECC*/
 
 	/* symmetric algorithm */
-	tpm_buf_append_u16(&template, TPM_ALG_AES);
+	tpm_buf_append_u16(template, TPM_ALG_AES);
 
 	/* bits for symmetric algorithm */
-	tpm_buf_append_u16(&template, AES_KEY_BITS);
+	tpm_buf_append_u16(template, AES_KEY_BITS);
 
 	/* algorithm mode (must be CFB) */
-	tpm_buf_append_u16(&template, TPM_ALG_CFB);
+	tpm_buf_append_u16(template, TPM_ALG_CFB);
 
 	/* scheme (NULL means any scheme) */
-	tpm_buf_append_u16(&template, TPM_ALG_NULL);
+	tpm_buf_append_u16(template, TPM_ALG_NULL);
 
 	/* ECC Curve ID */
-	tpm_buf_append_u16(&template, TPM2_ECC_NIST_P256);
+	tpm_buf_append_u16(template, TPM2_ECC_NIST_P256);
 
 	/* KDF Scheme */
-	tpm_buf_append_u16(&template, TPM_ALG_NULL);
+	tpm_buf_append_u16(template, TPM_ALG_NULL);
 
 	/* unique: key specific; for ECC it is two zero size points */
-	tpm_buf_append_u16(&template, 0);
-	tpm_buf_append_u16(&template, 0);
+	tpm_buf_append_u16(template, 0);
+	tpm_buf_append_u16(template, 0);
 
 	/* END parameters */
 
 	/* primary handle */
-	tpm_buf_append_u32(&buf, hierarchy);
-	tpm_buf_append_empty_auth(&buf, TPM2_RS_PW);
+	tpm_buf_append_u32(buf, hierarchy);
+	tpm_buf_append_empty_auth(buf, TPM2_RS_PW);
 
 	/* sensitive create size is 4 for two empty buffers */
-	tpm_buf_append_u16(&buf, 4);
+	tpm_buf_append_u16(buf, 4);
 
 	/* sensitive create auth data (empty) */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* sensitive create sensitive data (empty) */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* the public template */
-	tpm_buf_append(&buf, template.data, template.length);
-	tpm_buf_destroy(&template);
+	tpm_buf_append(buf, template->data, template->length);
 
 	/* outside info (empty) */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* creation PCR (none) */
-	tpm_buf_append_u32(&buf, 0);
+	tpm_buf_append_u32(buf, 0);
 
-	rc = tpm_transmit_cmd(chip, &buf, 0,
-			      "attempting to create NULL primary");
+	rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_CreatePrimary");
 
 	if (rc == TPM2_RC_SUCCESS)
-		rc = tpm2_parse_create_primary(chip, &buf, handle, hierarchy,
+		rc = tpm2_parse_create_primary(chip, buf, handle, hierarchy,
 					       name);
 
-	tpm_buf_destroy(&buf);
-
 	return rc;
 }
 
diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index 0ad5e18355e0..4229c71940cb 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -70,24 +70,25 @@ void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space)
 int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
 		      unsigned int *offset, u32 *handle)
 {
-	struct tpm_buf tbuf;
 	struct tpm2_context *ctx;
 	unsigned int body_size;
 	int rc;
 
-	rc = tpm_buf_init(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_LOAD);
-	if (rc)
-		return rc;
+	struct tpm_buf *tbuf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
+
+	tpm_buf_init(tbuf, TPM_BUFSIZE);
+	tpm_buf_reset(tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_LOAD);
 
 	ctx = (struct tpm2_context *)&buf[*offset];
 	body_size = sizeof(*ctx) + be16_to_cpu(ctx->blob_size);
-	tpm_buf_append(&tbuf, &buf[*offset], body_size);
+	tpm_buf_append(tbuf, &buf[*offset], body_size);
 
-	rc = tpm_transmit_cmd(chip, &tbuf, 4, NULL);
+	rc = tpm_transmit_cmd(chip, tbuf, 4, NULL);
 	if (rc < 0) {
 		dev_warn(&chip->dev, "%s: failed with a system error %d\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	} else if (tpm2_rc_value(rc) == TPM2_RC_HANDLE ||
 		   rc == TPM2_RC_REFERENCE_H0) {
@@ -102,64 +103,55 @@ int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
 		 * flushed outside the space
 		 */
 		*handle = 0;
-		tpm_buf_destroy(&tbuf);
 		return -ENOENT;
 	} else if (tpm2_rc_value(rc) == TPM2_RC_INTEGRITY) {
-		tpm_buf_destroy(&tbuf);
 		return -EINVAL;
 	} else if (rc > 0) {
 		dev_warn(&chip->dev, "%s: failed with a TPM error 0x%04X\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	}
 
-	*handle = be32_to_cpup((__be32 *)&tbuf.data[TPM_HEADER_SIZE]);
+	*handle = be32_to_cpup((__be32 *)&tbuf->data[TPM_HEADER_SIZE]);
 	*offset += body_size;
-
-	tpm_buf_destroy(&tbuf);
 	return 0;
 }
 
 int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf,
 		      unsigned int buf_size, unsigned int *offset)
 {
-	struct tpm_buf tbuf;
 	unsigned int body_size;
 	int rc;
 
-	rc = tpm_buf_init(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_SAVE);
-	if (rc)
-		return rc;
+	struct tpm_buf *tbuf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&tbuf, handle);
+	tpm_buf_init(tbuf, TPM_BUFSIZE);
+	tpm_buf_reset(tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_SAVE);
+	tpm_buf_append_u32(tbuf, handle);
 
-	rc = tpm_transmit_cmd(chip, &tbuf, 0, NULL);
+	rc = tpm_transmit_cmd(chip, tbuf, 0, NULL);
 	if (rc < 0) {
 		dev_warn(&chip->dev, "%s: failed with a system error %d\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	} else if (tpm2_rc_value(rc) == TPM2_RC_REFERENCE_H0) {
-		tpm_buf_destroy(&tbuf);
 		return -ENOENT;
 	} else if (rc) {
 		dev_warn(&chip->dev, "%s: failed with a TPM error 0x%04X\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	}
 
-	body_size = tpm_buf_length(&tbuf) - TPM_HEADER_SIZE;
+	body_size = tpm_buf_length(tbuf) - TPM_HEADER_SIZE;
 	if ((*offset + body_size) > buf_size) {
 		dev_warn(&chip->dev, "%s: out of backing storage\n", __func__);
-		tpm_buf_destroy(&tbuf);
 		return -ENOMEM;
 	}
 
-	memcpy(&buf[*offset], &tbuf.data[TPM_HEADER_SIZE], body_size);
+	memcpy(&buf[*offset], &tbuf->data[TPM_HEADER_SIZE], body_size);
 	*offset += body_size;
-	tpm_buf_destroy(&tbuf);
 	return 0;
 }
 
diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
index 0818bb517805..682dfc93845d 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -395,40 +395,36 @@ static bool vtpm_proxy_tpm_req_canceled(struct tpm_chip  *chip, u8 status)
 
 static int vtpm_proxy_request_locality(struct tpm_chip *chip, int locality)
 {
-	struct tpm_buf buf;
 	int rc;
 	const struct tpm_header *header;
 	struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev);
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
-		rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS,
-				  TPM2_CC_SET_LOCALITY);
+		tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_SET_LOCALITY);
 	else
-		rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND,
-				  TPM_ORD_SET_LOCALITY);
-	if (rc)
-		return rc;
-	tpm_buf_append_u8(&buf, locality);
+		tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SET_LOCALITY);
+
+	tpm_buf_append_u8(buf, locality);
 
 	proxy_dev->state |= STATE_DRIVER_COMMAND;
 
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to set locality");
+	rc = tpm_transmit_cmd(chip, buf, 0, "attempting to set locality");
 
 	proxy_dev->state &= ~STATE_DRIVER_COMMAND;
 
-	if (rc < 0) {
-		locality = rc;
-		goto out;
-	}
+	if (rc < 0)
+		return rc;
 
-	header = (const struct tpm_header *)buf.data;
+	header = (const struct tpm_header *)buf->data;
 	rc = be32_to_cpu(header->return_code);
 	if (rc)
 		locality = -1;
 
-out:
-	tpm_buf_destroy(&buf);
-
 	return locality;
 }
 
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index e86c22b30153..2ea181a35786 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -26,7 +26,8 @@
 #include <crypto/hash_info.h>
 #include <crypto/aes.h>
 
-#define TPM_DIGEST_SIZE 20	/* Max TPM v1.2 PCR size */
+#define TPM_DIGEST_SIZE		20	/* Max TPM v1.2 PCR size */
+#define TPM_BUFSIZE		4096
 
 #define TPM2_MAX_DIGEST_SIZE	SHA512_DIGEST_SIZE
 #define TPM2_MAX_PCR_BANKS	8
@@ -377,13 +378,15 @@ enum tpm_buf_flags {
 };
 
 /*
- * A string buffer type for constructing TPM commands.
+ * A buffer for constructing and parsing TPM commands, responses and sized
+ * (TPM2B) buffers.
  */
 struct tpm_buf {
-	u32 flags;
-	u32 length;
-	u8 *data;
+	u8 flags;
 	u8 handles;
+	u16 length;
+	u16 capacity;
+	u8 data[];
 };
 
 enum tpm2_object_attributes {
@@ -414,11 +417,10 @@ struct tpm2_hash {
 	unsigned int tpm_id;
 };
 
-int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal);
+void tpm_buf_init(struct tpm_buf *buf, u16 buf_size);
+void tpm_buf_init_sized(struct tpm_buf *buf, u16 buf_size);
 void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal);
-int tpm_buf_init_sized(struct tpm_buf *buf);
 void tpm_buf_reset_sized(struct tpm_buf *buf);
-void tpm_buf_destroy(struct tpm_buf *buf);
 u32 tpm_buf_length(struct tpm_buf *buf);
 void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length);
 void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value);
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index 636acb66a4f6..3ac204a902de 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -310,9 +310,8 @@ static int TSS_checkhmac2(unsigned char *buffer,
  * For key specific tpm requests, we will generate and send our
  * own TPM command packets using the drivers send function.
  */
-static int trusted_tpm_send(unsigned char *cmd, size_t buflen)
+static int trusted_tpm_send(void *cmd, size_t buflen)
 {
-	struct tpm_buf buf;
 	int rc;
 
 	if (!chip)
@@ -322,15 +321,12 @@ static int trusted_tpm_send(unsigned char *cmd, size_t buflen)
 	if (rc)
 		return rc;
 
-	buf.flags = 0;
-	buf.length = buflen;
-	buf.data = cmd;
 	dump_tpm_buf(cmd);
-	rc = tpm_transmit_cmd(chip, &buf, 4, "sending data");
+	rc = tpm_transmit_cmd(chip, cmd, 4, "sending data");
 	dump_tpm_buf(cmd);
 
+	/* Convert TPM error to -EPERM. */
 	if (rc > 0)
-		/* TPM error */
 		rc = -EPERM;
 
 	tpm_put_ops(chip);
@@ -624,23 +620,23 @@ static int tpm_unseal(struct tpm_buf *tb,
 static int key_seal(struct trusted_key_payload *p,
 		    struct trusted_key_options *o)
 {
-	struct tpm_buf tb;
 	int ret;
 
-	ret = tpm_buf_init(&tb, 0, 0);
-	if (ret)
-		return ret;
+	struct tpm_buf *tb __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!tb)
+		return -ENOMEM;
+
+	tpm_buf_init(tb, TPM_BUFSIZE);
 
 	/* include migratable flag at end of sealed key */
 	p->key[p->key_len] = p->migratable;
 
-	ret = tpm_seal(&tb, o->keytype, o->keyhandle, o->keyauth,
+	ret = tpm_seal(tb, o->keytype, o->keyhandle, o->keyauth,
 		       p->key, p->key_len + 1, p->blob, &p->blob_len,
 		       o->blobauth, o->pcrinfo, o->pcrinfo_len);
 	if (ret < 0)
 		pr_info("srkseal failed (%d)\n", ret);
 
-	tpm_buf_destroy(&tb);
 	return ret;
 }
 
@@ -650,14 +646,15 @@ static int key_seal(struct trusted_key_payload *p,
 static int key_unseal(struct trusted_key_payload *p,
 		      struct trusted_key_options *o)
 {
-	struct tpm_buf tb;
 	int ret;
 
-	ret = tpm_buf_init(&tb, 0, 0);
-	if (ret)
-		return ret;
+	struct tpm_buf *tb __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!tb)
+		return -ENOMEM;
+
+	tpm_buf_init(tb, TPM_BUFSIZE);
 
-	ret = tpm_unseal(&tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
+	ret = tpm_unseal(tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
 			 o->blobauth, p->key, &p->key_len);
 	if (ret < 0)
 		pr_info("srkunseal failed (%d)\n", ret);
@@ -665,7 +662,6 @@ static int key_unseal(struct trusted_key_payload *p,
 		/* pull migratable flag out of sealed key */
 		p->migratable = p->key[--p->key_len];
 
-	tpm_buf_destroy(&tb);
 	return ret;
 }
 
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 119d5152c0db..0a99bd051a25 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -212,13 +212,20 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		      struct trusted_key_options *options)
 {
 	off_t offset = TPM_HEADER_SIZE;
-	struct tpm_buf buf, sized;
 	int blob_len = 0;
 	u32 hash;
 	u32 flags;
 	int i;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	struct tpm_buf *sized __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!sized)
+		return -ENOMEM;
+
 	for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) {
 		if (options->hash == tpm2_hash_map[i].crypto_id) {
 			hash = tpm2_hash_map[i].tpm_id;
@@ -240,91 +247,79 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	if (rc)
 		goto out_put;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
-	if (rc) {
-		tpm2_end_auth_session(chip);
-		goto out_put;
-	}
-
-	rc = tpm_buf_init_sized(&sized);
-	if (rc) {
-		tpm_buf_destroy(&buf);
-		tpm2_end_auth_session(chip);
-		goto out_put;
-	}
-
-	tpm_buf_append_name(chip, &buf, options->keyhandle, NULL);
-	tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT,
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_init_sized(sized, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
+	tpm_buf_append_name(chip, buf, options->keyhandle, NULL);
+	tpm_buf_append_hmac_session(chip, buf, TPM2_SA_DECRYPT,
 				    options->keyauth, TPM_DIGEST_SIZE);
 
 	/* sensitive */
-	tpm_buf_append_u16(&sized, options->blobauth_len);
+	tpm_buf_append_u16(sized, options->blobauth_len);
 
 	if (options->blobauth_len)
-		tpm_buf_append(&sized, options->blobauth, options->blobauth_len);
+		tpm_buf_append(sized, options->blobauth, options->blobauth_len);
 
-	tpm_buf_append_u16(&sized, payload->key_len);
-	tpm_buf_append(&sized, payload->key, payload->key_len);
-	tpm_buf_append(&buf, sized.data, sized.length);
+	tpm_buf_append_u16(sized, payload->key_len);
+	tpm_buf_append(sized, payload->key, payload->key_len);
+	tpm_buf_append(buf, sized->data, sized->length);
 
 	/* public */
-	tpm_buf_reset_sized(&sized);
-	tpm_buf_append_u16(&sized, TPM_ALG_KEYEDHASH);
-	tpm_buf_append_u16(&sized, hash);
+	tpm_buf_init_sized(sized, TPM_BUFSIZE);
+	tpm_buf_append_u16(sized, TPM_ALG_KEYEDHASH);
+	tpm_buf_append_u16(sized, hash);
 
 	/* key properties */
 	flags = 0;
 	flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH;
 	flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT);
-	tpm_buf_append_u32(&sized, flags);
+	tpm_buf_append_u32(sized, flags);
 
 	/* policy */
-	tpm_buf_append_u16(&sized, options->policydigest_len);
+	tpm_buf_append_u16(sized, options->policydigest_len);
 	if (options->policydigest_len)
-		tpm_buf_append(&sized, options->policydigest, options->policydigest_len);
+		tpm_buf_append(sized, options->policydigest, options->policydigest_len);
 
 	/* public parameters */
-	tpm_buf_append_u16(&sized, TPM_ALG_NULL);
-	tpm_buf_append_u16(&sized, 0);
+	tpm_buf_append_u16(sized, TPM_ALG_NULL);
+	tpm_buf_append_u16(sized, 0);
 
-	tpm_buf_append(&buf, sized.data, sized.length);
+	tpm_buf_append(buf, sized->data, sized->length);
 
 	/* outside info */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* creation PCR */
-	tpm_buf_append_u32(&buf, 0);
+	tpm_buf_append_u32(buf, 0);
 
-	if (buf.flags & TPM_BUF_INVALID) {
+	if (buf->flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		tpm2_end_auth_session(chip);
 		goto out;
 	}
 
-	tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data");
-	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+	tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 4, "sealing data");
+	rc = tpm_buf_check_hmac_response(chip, buf, rc);
 	if (rc)
 		goto out;
 
-	blob_len = tpm_buf_read_u32(&buf, &offset);
-	if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_INVALID) {
+	blob_len = tpm_buf_read_u32(buf, &offset);
+	if (blob_len > MAX_BLOB_SIZE || buf->flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		goto out;
 	}
-	if (buf.length - offset < blob_len) {
+	if (buf->length - offset < blob_len) {
 		rc = -EFAULT;
 		goto out;
 	}
 
-	blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
-	if (blob_len < 0)
-		rc = blob_len;
+	blob_len = tpm2_key_encode(payload, options, &buf->data[offset],
+				   blob_len);
 
 out:
-	tpm_buf_destroy(&sized);
-	tpm_buf_destroy(&buf);
-
+	if (blob_len < 0)
+		rc = blob_len;
 	if (!rc)
 		payload->blob_len = blob_len;
 
@@ -351,7 +346,6 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 			 struct trusted_key_options *options,
 			 u32 *blob_handle)
 {
-	struct tpm_buf buf;
 	unsigned int private_len;
 	unsigned int public_len;
 	unsigned int blob_len;
@@ -359,6 +353,10 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	int rc;
 	u32 attrs;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	rc = tpm2_key_decode(payload, options, &blob);
 	if (rc) {
 		/* old form */
@@ -402,35 +400,30 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	if (rc)
 		return rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
-	if (rc) {
-		tpm2_end_auth_session(chip);
-		return rc;
-	}
-
-	tpm_buf_append_name(chip, &buf, options->keyhandle, NULL);
-	tpm_buf_append_hmac_session(chip, &buf, 0, options->keyauth,
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
+	tpm_buf_append_name(chip, buf, options->keyhandle, NULL);
+	tpm_buf_append_hmac_session(chip, buf, 0, options->keyauth,
 				    TPM_DIGEST_SIZE);
 
-	tpm_buf_append(&buf, blob, blob_len);
+	tpm_buf_append(buf, blob, blob_len);
 
-	if (buf.flags & TPM_BUF_INVALID) {
+	if (buf->flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		tpm2_end_auth_session(chip);
 		goto out;
 	}
 
-	tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob");
-	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+	tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 4, "loading blob");
+	rc = tpm_buf_check_hmac_response(chip, buf, rc);
 	if (!rc)
 		*blob_handle = be32_to_cpup(
-			(__be32 *) &buf.data[TPM_HEADER_SIZE]);
+			(__be32 *)&buf->data[TPM_HEADER_SIZE]);
 
 out:
 	if (blob != payload->blob)
 		kfree(blob);
-	tpm_buf_destroy(&buf);
 
 	return tpm_ret_to_err(rc);
 }
@@ -453,26 +446,25 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 			   u32 blob_handle)
 {
 	struct tpm_header *head;
-	struct tpm_buf buf;
 	u16 data_len;
 	int offset;
 	u8 *data;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	rc = tpm2_start_auth_session(chip);
 	if (rc)
 		return rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
-	if (rc) {
-		tpm2_end_auth_session(chip);
-		return rc;
-	}
-
-	tpm_buf_append_name(chip, &buf, blob_handle, NULL);
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
+	tpm_buf_append_name(chip, buf, blob_handle, NULL);
 
 	if (!options->policyhandle) {
-		tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT,
+		tpm_buf_append_hmac_session(chip, buf, TPM2_SA_ENCRYPT,
 					    options->blobauth,
 					    options->blobauth_len);
 	} else {
@@ -481,39 +473,35 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		 * the password will end up being unencrypted on the bus, as
 		 * HMAC nonce cannot be calculated for it.
 		 */
-		tpm_buf_append_u32(&buf, 9 + options->blobauth_len);
-		tpm_buf_append_u32(&buf, options->policyhandle);
-		tpm_buf_append_u16(&buf, 0);
-		tpm_buf_append_u8(&buf, 0);
-		tpm_buf_append_u16(&buf, options->blobauth_len);
-		tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
+		tpm_buf_append_u32(buf, 9 + options->blobauth_len);
+		tpm_buf_append_u32(buf, options->policyhandle);
+		tpm_buf_append_u16(buf, 0);
+		tpm_buf_append_u8(buf, 0);
+		tpm_buf_append_u16(buf, options->blobauth_len);
+		tpm_buf_append(buf, options->blobauth, options->blobauth_len);
 		if (tpm2_chip_auth(chip)) {
-			tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, NULL, 0);
+			tpm_buf_append_hmac_session(chip, buf, TPM2_SA_ENCRYPT, NULL, 0);
 		} else  {
-			offset = buf.handles * 4 + TPM_HEADER_SIZE;
-			head = (struct tpm_header *)buf.data;
-			if (tpm_buf_length(&buf) == offset)
+			offset = buf->handles * 4 + TPM_HEADER_SIZE;
+			head = (struct tpm_header *)buf->data;
+			if (tpm_buf_length(buf) == offset)
 				head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
 		}
 	}
 
-	tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
-	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+	tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 6, "unsealing");
+	rc = tpm_buf_check_hmac_response(chip, buf, rc);
 
 	if (!rc) {
 		data_len = be16_to_cpup(
-			(__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
-		if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE) {
-			rc = -EFAULT;
-			goto out;
-		}
+			(__be16 *)&buf->data[TPM_HEADER_SIZE + 4]);
+		if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE)
+			return -EFAULT;
 
-		if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 6 + data_len) {
-			rc = -EFAULT;
-			goto out;
-		}
-		data = &buf.data[TPM_HEADER_SIZE + 6];
+		if (tpm_buf_length(buf) < TPM_HEADER_SIZE + 6 + data_len)
+			return -EFAULT;
+		data = &buf->data[TPM_HEADER_SIZE + 6];
 
 		if (payload->old_format) {
 			/* migratable flag is at the end of the key */
@@ -530,8 +518,6 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		}
 	}
 
-out:
-	tpm_buf_destroy(&buf);
 	return tpm_ret_to_err(rc);
 }
 
-- 
2.39.5


^ permalink raw reply related

* Re: [PATCH v4 0/9] tpm: Decouple Trenchboot dependencies
From: Jarkko Sakkinen @ 2025-09-30 22:31 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, David Howells, Paul Moore, James Morris,
	Serge E. Hallyn, open list:KEYS/KEYRINGS,
	open list:SECURITY SUBSYSTEM, open list
In-Reply-To: <20250930221707.1373912-1-jarkko@kernel.org>

On Wed, Oct 01, 2025 at 01:16:58AM +0300, Jarkko Sakkinen wrote:
> Overview
> ========
> 
> Decouple TPM driver features relevant for Trenchboot and make tpm-buf
> robust and decoupled entity from the rest of driver. By doing this, code
> can be easily linked to the early boot code.
> 
> Goals and scope
> ===============
> 
> This patch set contains only changes, which are acceptable to mainline
> driver without existence Trenchboot feature.
> 
> At the same the primary goal of the included is to make driver code 
> robust enough to meet Trenchboot's requirements.
> 
> These constraints should define a meaningful DoD for this patch set.
> 
> v4:
> - PCR patch has been removed because it does not fly without Trenchboot
>   context.
> v3:
> - I think 6.19 is a better goal for this and thus expanded the series to
>   be a generic Trenchboot enablers series. This version also consolidates my two separate ongoing series.
> v2:
> - While including fixes from v1, this patch set has a refocus in order to
>   do minimal changes to make code base more compatible  Trenchboot.
> 
> Jarkko Sakkinen (9):
>   tpm: Cap the number of PCR banks
>   tpm: Use -EPERM as fallback error code in tpm_ret_to_err
>   KEYS: trusted: Use tpm_ret_to_err() in trusted_tpm2
>   tpm2-sessions: Remove 'attributes' from tpm_buf_append_auth
>   tpm2-sessions: Unmask tpm_buf_append_hmac_session()
>   KEYS: trusted: Open code tpm2_buf_append()
>   tpm-buf: check for corruption in tpm_buf_append_handle()
>   tpm-buf: Remove chip parameter from tpm_buf_append_handle
>   tpm-buf: Enable managed and stack allocations.
> 
>  drivers/char/tpm/tpm-buf.c                | 141 ++++++----
>  drivers/char/tpm/tpm-chip.c               |  13 +-
>  drivers/char/tpm/tpm-sysfs.c              |  21 +-
>  drivers/char/tpm/tpm.h                    |   2 -
>  drivers/char/tpm/tpm1-cmd.c               | 185 +++++--------
>  drivers/char/tpm/tpm2-cmd.c               | 313 ++++++++++------------
>  drivers/char/tpm/tpm2-sessions.c          | 129 +++++----
>  drivers/char/tpm/tpm2-space.c             |  44 ++-
>  drivers/char/tpm/tpm_vtpm_proxy.c         |  30 +--
>  include/linux/tpm.h                       |  65 ++---
>  security/keys/trusted-keys/trusted_tpm1.c |  34 ++-
>  security/keys/trusted-keys/trusted_tpm2.c | 237 +++++++---------
>  12 files changed, 542 insertions(+), 672 deletions(-)
> 
> -- 
> 2.39.5
> 

I've done testing in sequence of the patch set for every patch by
running:

1. https://codeberg.org/jarkko/linux-tpmdd-test/src/branch/main/board/pc_x86_64/test_tpm2_kselftest.exp.in
2. https://codeberg.org/jarkko/linux-tpmdd-test/src/branch/main/board/pc_x86_64/test_tpm2_trusted.exp.in

I also separately booted for the managed allocations patch with
swtpm in TPM 1.2 mode and did some manual testing.

Changes have been tested with HMAC encryption on to make sure that
tpm2-sessions changes have beeen applied correctly.

BR, Jarkko

^ permalink raw reply

* [PATCH v5 0/9] Prepare TPM driver for Trenchboot
From: Jarkko Sakkinen @ 2025-09-30 23:19 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM, open list

Overview
========

Prepare TPM driver for Trenchboot by making tpm-buf easy to compile as an
independent compilation unit, and generally be IO and memory agnostic.
This allows Trenchboot easily use this code to build and parse TPM 1.2 and
TPM 2.0 commands.

Goals and scope
===============

This patch set contains only changes, which are acceptable to the mainline
driver without existence of Trenchboot feature.

v5:
- Order sobs correctly.
- Fixed a minor glitch in 9/9.
v4:
- PCR patch has been removed because it does not fly without Trenchboot
  context.
v3:
- I think 6.19 is a better goal for this and thus expanded the series to
  be a generic Trenchboot enablers series. This version also consolidates
  my two separate ongoing series.
v2:
- While including fixes from v1, this patch set has a refocus in order to
  do minimal changes to make code base more compatible  Trenchboot.

Jarkko Sakkinen (9):
  tpm: Cap the number of PCR banks
  tpm: Use -EPERM as fallback error code in tpm_ret_to_err
  KEYS: trusted: Use tpm_ret_to_err() in trusted_tpm2
  tpm2-sessions: Remove 'attributes' from tpm_buf_append_auth
  tpm2-sessions: Unmask tpm_buf_append_hmac_session()
  KEYS: trusted: Open code tpm2_buf_append()
  tpm-buf: check for corruption in tpm_buf_append_handle()
  tpm-buf: Remove chip parameter from tpm_buf_append_handle
  tpm-buf: Enable managed and stack allocations.

 drivers/char/tpm/tpm-buf.c                | 141 ++++++----
 drivers/char/tpm/tpm-chip.c               |  13 +-
 drivers/char/tpm/tpm-sysfs.c              |  21 +-
 drivers/char/tpm/tpm.h                    |   2 -
 drivers/char/tpm/tpm1-cmd.c               | 185 +++++--------
 drivers/char/tpm/tpm2-cmd.c               | 313 ++++++++++------------
 drivers/char/tpm/tpm2-sessions.c          | 129 +++++----
 drivers/char/tpm/tpm2-space.c             |  44 ++-
 drivers/char/tpm/tpm_vtpm_proxy.c         |  30 +--
 include/linux/tpm.h                       |  65 ++---
 security/keys/trusted-keys/trusted_tpm1.c |  34 ++-
 security/keys/trusted-keys/trusted_tpm2.c | 241 +++++++----------
 12 files changed, 544 insertions(+), 674 deletions(-)

-- 
2.39.5


^ permalink raw reply

* [PATCH v5 1/9] tpm: Cap the number of PCR banks
From: Jarkko Sakkinen @ 2025-09-30 23:19 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Roberto Sassu,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, open list,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930231958.1437783-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

tpm2_get_pcr_allocation() does not cap any upper limit for the number of
banks. Cap the limit to four banks so that out of bounds values coming
from external I/O cause on only limited harm.

Cc: Roberto Sassu <roberto.sassu@huawei.com>
Fixes: bcfff8384f6c ("tpm: dynamically allocate the allocated_banks array")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
---
v4:
- Revert spurious changes from include/linux/tpm.h.
- Increase TPM2_MAX_BANKS to 8.
- Rename TPM2_MAX_BANKS as TPM2_MAX_PCR_BANKS for the sake of clarity.
v3:
- Wrote a more clear commit message.
- Fixed pr_err() message.
v2:
- A new patch.
---
 drivers/char/tpm/tpm-chip.c | 13 +++++++++----
 drivers/char/tpm/tpm.h      |  1 -
 drivers/char/tpm/tpm1-cmd.c | 25 -------------------------
 drivers/char/tpm/tpm2-cmd.c |  8 +++-----
 include/linux/tpm.h         |  8 +++++---
 5 files changed, 17 insertions(+), 38 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 687f6d8cd601..9a6538f76f50 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -559,14 +559,19 @@ static int tpm_add_hwrng(struct tpm_chip *chip)
 
 static int tpm_get_pcr_allocation(struct tpm_chip *chip)
 {
-	int rc;
+	int rc = 0;
 
 	if (tpm_is_firmware_upgrade(chip))
 		return 0;
 
-	rc = (chip->flags & TPM_CHIP_FLAG_TPM2) ?
-	     tpm2_get_pcr_allocation(chip) :
-	     tpm1_get_pcr_allocation(chip);
+	if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
+		chip->allocated_banks[0].alg_id = TPM_ALG_SHA1;
+		chip->allocated_banks[0].digest_size = hash_digest_size[HASH_ALGO_SHA1];
+		chip->allocated_banks[0].crypto_id = HASH_ALGO_SHA1;
+		chip->nr_allocated_banks = 1;
+	} else {
+		rc = tpm2_get_pcr_allocation(chip);
+	}
 
 	if (rc > 0)
 		return -ENODEV;
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 57ef8589f5f5..769fa6b00c54 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -252,7 +252,6 @@ int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf);
 ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 		    const char *desc, size_t min_cap_length);
 int tpm1_get_random(struct tpm_chip *chip, u8 *out, size_t max);
-int tpm1_get_pcr_allocation(struct tpm_chip *chip);
 unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
 int tpm_pm_suspend(struct device *dev);
 int tpm_pm_resume(struct device *dev);
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index cf64c7385105..5c49bdff33de 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -786,28 +786,3 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 
 	return rc;
 }
-
-/**
- * tpm1_get_pcr_allocation() - initialize the allocated bank
- * @chip: TPM chip to use.
- *
- * The function initializes the SHA1 allocated bank to extend PCR
- *
- * Return:
- * * 0 on success,
- * * < 0 on error.
- */
-int tpm1_get_pcr_allocation(struct tpm_chip *chip)
-{
-	chip->allocated_banks = kcalloc(1, sizeof(*chip->allocated_banks),
-					GFP_KERNEL);
-	if (!chip->allocated_banks)
-		return -ENOMEM;
-
-	chip->allocated_banks[0].alg_id = TPM_ALG_SHA1;
-	chip->allocated_banks[0].digest_size = hash_digest_size[HASH_ALGO_SHA1];
-	chip->allocated_banks[0].crypto_id = HASH_ALGO_SHA1;
-	chip->nr_allocated_banks = 1;
-
-	return 0;
-}
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 7d77f6fbc152..97501c567c34 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -538,11 +538,9 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 
 	nr_possible_banks = be32_to_cpup(
 		(__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
-
-	chip->allocated_banks = kcalloc(nr_possible_banks,
-					sizeof(*chip->allocated_banks),
-					GFP_KERNEL);
-	if (!chip->allocated_banks) {
+	if (nr_possible_banks > TPM2_MAX_PCR_BANKS) {
+		pr_err("tpm: unexpected number of banks: %u > %u",
+		       nr_possible_banks, TPM2_MAX_PCR_BANKS);
 		rc = -ENOMEM;
 		goto out;
 	}
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 900c81a2bc41..f998dca4ea07 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -27,7 +27,9 @@
 #include <crypto/aes.h>
 
 #define TPM_DIGEST_SIZE 20	/* Max TPM v1.2 PCR size */
-#define TPM_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE
+
+#define TPM2_MAX_DIGEST_SIZE	SHA512_DIGEST_SIZE
+#define TPM2_MAX_PCR_BANKS	8
 
 struct tpm_chip;
 struct trusted_key_payload;
@@ -69,7 +71,7 @@ enum tpm2_curves {
 
 struct tpm_digest {
 	u16 alg_id;
-	u8 digest[TPM_MAX_DIGEST_SIZE];
+	u8 digest[TPM2_MAX_DIGEST_SIZE];
 } __packed;
 
 struct tpm_bank_info {
@@ -190,7 +192,7 @@ struct tpm_chip {
 	unsigned int groups_cnt;
 
 	u32 nr_allocated_banks;
-	struct tpm_bank_info *allocated_banks;
+	struct tpm_bank_info allocated_banks[TPM2_MAX_PCR_BANKS];
 #ifdef CONFIG_ACPI
 	acpi_handle acpi_dev_handle;
 	char ppi_version[TPM_PPI_VERSION_LEN + 1];
-- 
2.39.5


^ permalink raw reply related

* [PATCH v5 2/9] tpm: Use -EPERM as fallback error code in tpm_ret_to_err
From: Jarkko Sakkinen @ 2025-09-30 23:19 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Stefano Garzarella,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, open list,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930231958.1437783-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Using -EFAULT as the tpm_ret_to_err() fallback error code causes makes it
incompatible on how trusted keys transmute TPM return codes.

Change the fallback as -EPERM in order to gain compatibility with trusted
keys. In addition, map TPM_RC_HASH to -EINVAL in order to be compatible
with tpm2_seal_trusted() return values.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
---
v4:
- No changes.
v3:
- Removed fixes tag as it hardly categorizes as a bug fix.
v2:
- Split trusted_tpm2 change to a separate patch.
---
 include/linux/tpm.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index f998dca4ea07..dff558140c69 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -457,8 +457,10 @@ static inline ssize_t tpm_ret_to_err(ssize_t ret)
 		return 0;
 	case TPM2_RC_SESSION_MEMORY:
 		return -ENOMEM;
+	case TPM2_RC_HASH:
+		return -EINVAL;
 	default:
-		return -EFAULT;
+		return -EPERM;
 	}
 }
 
-- 
2.39.5


^ permalink raw reply related

* [PATCH v5 3/9] KEYS: trusted: Use tpm_ret_to_err() in trusted_tpm2
From: Jarkko Sakkinen @ 2025-09-30 23:19 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Stefano Garzarella,
	David Howells, Jarkko Sakkinen, Paul Moore, James Morris,
	Serge E. Hallyn, James Bottomley, Mimi Zohar,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM, open list
In-Reply-To: <20250930231958.1437783-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Use tpm_ret_to_err() to transmute TPM return codes in trusted_tpm2.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
---
v4:
- No changes.
v3:
- No changes.
v2:
- New patch split out from the fix.
---
 security/keys/trusted-keys/trusted_tpm2.c | 26 ++++++-----------------
 1 file changed, 7 insertions(+), 19 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 024be262702f..e165b117bbca 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -348,25 +348,19 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	}
 
 	blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
+	if (blob_len < 0)
+		rc = blob_len;
 
 out:
 	tpm_buf_destroy(&sized);
 	tpm_buf_destroy(&buf);
 
-	if (rc > 0) {
-		if (tpm2_rc_value(rc) == TPM2_RC_HASH)
-			rc = -EINVAL;
-		else
-			rc = -EPERM;
-	}
-	if (blob_len < 0)
-		rc = blob_len;
-	else
+	if (!rc)
 		payload->blob_len = blob_len;
 
 out_put:
 	tpm_put_ops(chip);
-	return rc;
+	return tpm_ret_to_err(rc);
 }
 
 /**
@@ -468,10 +462,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 		kfree(blob);
 	tpm_buf_destroy(&buf);
 
-	if (rc > 0)
-		rc = -EPERM;
-
-	return rc;
+	return tpm_ret_to_err(rc);
 }
 
 /**
@@ -534,8 +525,6 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 	tpm_buf_fill_hmac_session(chip, &buf);
 	rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
 	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
-	if (rc > 0)
-		rc = -EPERM;
 
 	if (!rc) {
 		data_len = be16_to_cpup(
@@ -568,7 +557,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 
 out:
 	tpm_buf_destroy(&buf);
-	return rc;
+	return tpm_ret_to_err(rc);
 }
 
 /**
@@ -600,6 +589,5 @@ int tpm2_unseal_trusted(struct tpm_chip *chip,
 
 out:
 	tpm_put_ops(chip);
-
-	return rc;
+	return tpm_ret_to_err(rc);
 }
-- 
2.39.5


^ permalink raw reply related

* [PATCH v5 4/9] tpm2-sessions: Remove 'attributes' from tpm_buf_append_auth
From: Jarkko Sakkinen @ 2025-09-30 23:19 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Jonathan McDowell,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, Roberto Sassu,
	Mimi Zohar, open list, open list:KEYS/KEYRINGS,
	open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930231958.1437783-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

In a previous bug fix, 'attributes' was added by mistake to
tpm_buf_append_auth(). Remove the parameter.

Fixes: 27184f8905ba ("tpm: Opt-in in disable PCR integrity protection")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
---
v4:
- No changes.
v3:
- No changes
v2:
- Uncorrupt the patch.
---
 drivers/char/tpm/tpm2-cmd.c      | 2 +-
 drivers/char/tpm/tpm2-sessions.c | 5 ++---
 include/linux/tpm.h              | 2 +-
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 97501c567c34..bf8294e3d8f2 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -191,7 +191,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 		tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0);
 	} else {
 		tpm_buf_append_handle(chip, &buf, pcr_idx);
-		tpm_buf_append_auth(chip, &buf, 0, NULL, 0);
+		tpm_buf_append_auth(chip, &buf, NULL, 0);
 	}
 
 	tpm_buf_append_u32(&buf, chip->nr_allocated_banks);
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 6d03c224e6b2..13f019d1312a 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -266,7 +266,7 @@ void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
 EXPORT_SYMBOL_GPL(tpm_buf_append_name);
 
 void tpm_buf_append_auth(struct tpm_chip *chip, struct tpm_buf *buf,
-			 u8 attributes, u8 *passphrase, int passphrase_len)
+			 u8 *passphrase, int passphrase_len)
 {
 	/* offset tells us where the sessions area begins */
 	int offset = buf->handles * 4 + TPM_HEADER_SIZE;
@@ -327,8 +327,7 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf,
 #endif
 
 	if (!tpm2_chip_auth(chip)) {
-		tpm_buf_append_auth(chip, buf, attributes, passphrase,
-				    passphrase_len);
+		tpm_buf_append_auth(chip, buf, passphrase, passphrase_len);
 		return;
 	}
 
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index dff558140c69..5b44222a36c4 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -535,7 +535,7 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf,
 				 u8 attributes, u8 *passphrase,
 				 int passphraselen);
 void tpm_buf_append_auth(struct tpm_chip *chip, struct tpm_buf *buf,
-			 u8 attributes, u8 *passphrase, int passphraselen);
+			 u8 *passphrase, int passphraselen);
 static inline void tpm_buf_append_hmac_session_opt(struct tpm_chip *chip,
 						   struct tpm_buf *buf,
 						   u8 attributes,
-- 
2.39.5


^ permalink raw reply related

* [PATCH v5 5/9] tpm2-sessions: Unmask tpm_buf_append_hmac_session()
From: Jarkko Sakkinen @ 2025-09-30 23:19 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Jonathan McDowell,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, James Bottomley,
	Mimi Zohar, open list, open list:KEYS/KEYRINGS,
	open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930231958.1437783-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Open code tpm_buf_append_hmac_session_opt() in order to unmask the code
paths in the call sites of tpm_buf_append_hmac_session().

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
---
v4:
- Fixed typo in short summary.
v3:
- No changes.
v2:
- Uncorrupt the patch.
---
 drivers/char/tpm/tpm2-cmd.c               | 14 +++++++++++---
 include/linux/tpm.h                       | 23 -----------------------
 security/keys/trusted-keys/trusted_tpm2.c | 12 ++++++++++--
 3 files changed, 21 insertions(+), 28 deletions(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index bf8294e3d8f2..254003e5dd8b 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -257,9 +257,17 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 
 	do {
 		tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
-		tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT
-						| TPM2_SA_CONTINUE_SESSION,
-						NULL, 0);
+		if (tpm2_chip_auth(chip)) {
+			tpm_buf_append_hmac_session(chip, &buf,
+						    TPM2_SA_ENCRYPT |
+						    TPM2_SA_CONTINUE_SESSION,
+						    NULL, 0);
+		} else  {
+			offset = buf.handles * 4 + TPM_HEADER_SIZE;
+			head = (struct tpm_header *)buf.data;
+			if (tpm_buf_length(&buf) == offset)
+				head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
+		}
 		tpm_buf_append_u16(&buf, num_bytes);
 		tpm_buf_fill_hmac_session(chip, &buf);
 		err = tpm_transmit_cmd(chip, &buf,
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 5b44222a36c4..e3c65d33e041 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -536,29 +536,6 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf,
 				 int passphraselen);
 void tpm_buf_append_auth(struct tpm_chip *chip, struct tpm_buf *buf,
 			 u8 *passphrase, int passphraselen);
-static inline void tpm_buf_append_hmac_session_opt(struct tpm_chip *chip,
-						   struct tpm_buf *buf,
-						   u8 attributes,
-						   u8 *passphrase,
-						   int passphraselen)
-{
-	struct tpm_header *head;
-	int offset;
-
-	if (tpm2_chip_auth(chip)) {
-		tpm_buf_append_hmac_session(chip, buf, attributes, passphrase, passphraselen);
-	} else  {
-		offset = buf->handles * 4 + TPM_HEADER_SIZE;
-		head = (struct tpm_header *)buf->data;
-
-		/*
-		 * If the only sessions are optional, the command tag must change to
-		 * TPM2_ST_NO_SESSIONS.
-		 */
-		if (tpm_buf_length(buf) == offset)
-			head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
-	}
-}
 
 #ifdef CONFIG_TCG_TPM2_HMAC
 
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index e165b117bbca..c414a7006d78 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -482,8 +482,10 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 			   struct trusted_key_options *options,
 			   u32 blob_handle)
 {
+	struct tpm_header *head;
 	struct tpm_buf buf;
 	u16 data_len;
+	int offset;
 	u8 *data;
 	int rc;
 
@@ -518,8 +520,14 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		tpm2_buf_append_auth(&buf, options->policyhandle,
 				     NULL /* nonce */, 0, 0,
 				     options->blobauth, options->blobauth_len);
-		tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT,
-						NULL, 0);
+		if (tpm2_chip_auth(chip)) {
+			tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, NULL, 0);
+		} else  {
+			offset = buf.handles * 4 + TPM_HEADER_SIZE;
+			head = (struct tpm_header *)buf.data;
+			if (tpm_buf_length(&buf) == offset)
+				head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
+		}
 	}
 
 	tpm_buf_fill_hmac_session(chip, &buf);
-- 
2.39.5


^ permalink raw reply related

* [PATCH v5 6/9] KEYS: trusted: Open code tpm2_buf_append()
From: Jarkko Sakkinen @ 2025-09-30 23:19 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Jonathan McDowell,
	David Howells, Jarkko Sakkinen, Paul Moore, James Morris,
	Serge E. Hallyn, James Bottomley, Mimi Zohar,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM, open list
In-Reply-To: <20250930231958.1437783-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

tpm2_buf_append_auth() has only single call site and most of its parameters
are redundant. Open code it to the call site. Remove illegit FIXME comment
as there is no categorized bug and replace it with more sane comment about
implementation (i.e. "non-opionated inline comment").

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Jonathan McDowell <noodles@earth.li>
---
v4:
- No changes:
v3:
- No changes.
v2:
- No changes.
---
 security/keys/trusted-keys/trusted_tpm2.c | 51 ++++-------------------
 1 file changed, 9 insertions(+), 42 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index c414a7006d78..8e3b283a59b2 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -198,36 +198,6 @@ int tpm2_key_priv(void *context, size_t hdrlen,
 	return 0;
 }
 
-/**
- * tpm2_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer.
- *
- * @buf: an allocated tpm_buf instance
- * @session_handle: session handle
- * @nonce: the session nonce, may be NULL if not used
- * @nonce_len: the session nonce length, may be 0 if not used
- * @attributes: the session attributes
- * @hmac: the session HMAC or password, may be NULL if not used
- * @hmac_len: the session HMAC or password length, maybe 0 if not used
- */
-static void tpm2_buf_append_auth(struct tpm_buf *buf, u32 session_handle,
-				 const u8 *nonce, u16 nonce_len,
-				 u8 attributes,
-				 const u8 *hmac, u16 hmac_len)
-{
-	tpm_buf_append_u32(buf, 9 + nonce_len + hmac_len);
-	tpm_buf_append_u32(buf, session_handle);
-	tpm_buf_append_u16(buf, nonce_len);
-
-	if (nonce && nonce_len)
-		tpm_buf_append(buf, nonce, nonce_len);
-
-	tpm_buf_append_u8(buf, attributes);
-	tpm_buf_append_u16(buf, hmac_len);
-
-	if (hmac && hmac_len)
-		tpm_buf_append(buf, hmac, hmac_len);
-}
-
 /**
  * tpm2_seal_trusted() - seal the payload of a trusted key
  *
@@ -507,19 +477,16 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 					    options->blobauth_len);
 	} else {
 		/*
-		 * FIXME: The policy session was generated outside the
-		 * kernel so we don't known the nonce and thus can't
-		 * calculate a HMAC on it.  Therefore, the user can
-		 * only really use TPM2_PolicyPassword and we must
-		 * send down the plain text password, which could be
-		 * intercepted.  We can still encrypt the returned
-		 * key, but that's small comfort since the interposer
-		 * could repeat our actions with the exfiltrated
-		 * password.
+		 * The policy session is generated outside the kernel, and thus
+		 * the password will end up being unencrypted on the bus, as
+		 * HMAC nonce cannot be calculated for it.
 		 */
-		tpm2_buf_append_auth(&buf, options->policyhandle,
-				     NULL /* nonce */, 0, 0,
-				     options->blobauth, options->blobauth_len);
+		tpm_buf_append_u32(&buf, 9 + options->blobauth_len);
+		tpm_buf_append_u32(&buf, options->policyhandle);
+		tpm_buf_append_u16(&buf, 0);
+		tpm_buf_append_u8(&buf, 0);
+		tpm_buf_append_u16(&buf, options->blobauth_len);
+		tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
 		if (tpm2_chip_auth(chip)) {
 			tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, NULL, 0);
 		} else  {
-- 
2.39.5


^ permalink raw reply related

* [PATCH v5 7/9] tpm-buf: check for corruption in tpm_buf_append_handle()
From: Jarkko Sakkinen @ 2025-09-30 23:19 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Jonathan McDowell,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, James Bottomley,
	Mimi Zohar, open list, open list:KEYS/KEYRINGS,
	open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930231958.1437783-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Unify TPM_BUF_BOUNDARY_ERROR and TPM_BUF_OVERFLOW into TPM_BUF_INVALID
flag because semantically they are identical.

Test and set TPM_BUF_INVALID in tpm_buf_append_handle() following the
pattern from other functions in tpm-buf.c.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
---
v4:
- No changes.
v3:
- No changes.
v2:
- A new patch.
---
 drivers/char/tpm/tpm-buf.c                | 14 ++++++++------
 include/linux/tpm.h                       |  8 +++-----
 security/keys/trusted-keys/trusted_tpm2.c |  6 +++---
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index dc882fc9fa9e..69ee77400539 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -104,13 +104,12 @@ EXPORT_SYMBOL_GPL(tpm_buf_length);
  */
 void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
 {
-	/* Return silently if overflow has already happened. */
-	if (buf->flags & TPM_BUF_OVERFLOW)
+	if (buf->flags & TPM_BUF_INVALID)
 		return;
 
 	if ((buf->length + new_length) > PAGE_SIZE) {
 		WARN(1, "tpm_buf: write overflow\n");
-		buf->flags |= TPM_BUF_OVERFLOW;
+		buf->flags |= TPM_BUF_INVALID;
 		return;
 	}
 
@@ -157,8 +156,12 @@ EXPORT_SYMBOL_GPL(tpm_buf_append_u32);
  */
 void tpm_buf_append_handle(struct tpm_chip *chip, struct tpm_buf *buf, u32 handle)
 {
+	if (buf->flags & TPM_BUF_INVALID)
+		return;
+
 	if (buf->flags & TPM_BUF_TPM2B) {
 		dev_err(&chip->dev, "Invalid buffer type (TPM2B)\n");
+		buf->flags |= TPM_BUF_INVALID;
 		return;
 	}
 
@@ -177,14 +180,13 @@ static void tpm_buf_read(struct tpm_buf *buf, off_t *offset, size_t count, void
 {
 	off_t next_offset;
 
-	/* Return silently if overflow has already happened. */
-	if (buf->flags & TPM_BUF_BOUNDARY_ERROR)
+	if (buf->flags & TPM_BUF_INVALID)
 		return;
 
 	next_offset = *offset + count;
 	if (next_offset > buf->length) {
 		WARN(1, "tpm_buf: read out of boundary\n");
-		buf->flags |= TPM_BUF_BOUNDARY_ERROR;
+		buf->flags |= TPM_BUF_INVALID;
 		return;
 	}
 
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index e3c65d33e041..4613216e9d95 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -370,12 +370,10 @@ struct tpm_header {
 } __packed;
 
 enum tpm_buf_flags {
-	/* the capacity exceeded: */
-	TPM_BUF_OVERFLOW	= BIT(0),
 	/* TPM2B format: */
-	TPM_BUF_TPM2B		= BIT(1),
-	/* read out of boundary: */
-	TPM_BUF_BOUNDARY_ERROR	= BIT(2),
+	TPM_BUF_TPM2B		= BIT(0),
+	/* The buffer is in invalid and unusable state: */
+	TPM_BUF_INVALID		= BIT(1),
 };
 
 /*
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 8e3b283a59b2..119d5152c0db 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -295,7 +295,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	/* creation PCR */
 	tpm_buf_append_u32(&buf, 0);
 
-	if (buf.flags & TPM_BUF_OVERFLOW) {
+	if (buf.flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		tpm2_end_auth_session(chip);
 		goto out;
@@ -308,7 +308,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		goto out;
 
 	blob_len = tpm_buf_read_u32(&buf, &offset);
-	if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_BOUNDARY_ERROR) {
+	if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		goto out;
 	}
@@ -414,7 +414,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 
 	tpm_buf_append(&buf, blob, blob_len);
 
-	if (buf.flags & TPM_BUF_OVERFLOW) {
+	if (buf.flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		tpm2_end_auth_session(chip);
 		goto out;
-- 
2.39.5


^ permalink raw reply related

* [PATCH v5 8/9] tpm-buf: Remove chip parameter from tpm_buf_append_handle
From: Jarkko Sakkinen @ 2025-09-30 23:19 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Jonathan McDowell,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, open list,
	open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930231958.1437783-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Remove chip parameter from tpm_buf_append_handle() in order to maintain
decoupled state with tpm-buf. This is mandatory change in order to re-use
the module in early boot code of Trenchboot, and the binding itself brings
no benefit. Use WARN like in other functions, as the error condition can
happen only as a net effect of a trivial programming mistake.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
---
v4:
- No changes.
v3:
- No changes.
v2:
- No changes.
---
 drivers/char/tpm/tpm-buf.c       | 5 ++---
 drivers/char/tpm/tpm2-cmd.c      | 2 +-
 drivers/char/tpm/tpm2-sessions.c | 2 +-
 include/linux/tpm.h              | 2 +-
 4 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index 69ee77400539..1b9dee0d0681 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -147,20 +147,19 @@ EXPORT_SYMBOL_GPL(tpm_buf_append_u32);
 
 /**
  * tpm_buf_append_handle() - Add a handle
- * @chip:	&tpm_chip instance
  * @buf:	&tpm_buf instance
  * @handle:	a TPM object handle
  *
  * Add a handle to the buffer, and increase the count tracking the number of
  * handles in the command buffer. Works only for command buffers.
  */
-void tpm_buf_append_handle(struct tpm_chip *chip, struct tpm_buf *buf, u32 handle)
+void tpm_buf_append_handle(struct tpm_buf *buf, u32 handle)
 {
 	if (buf->flags & TPM_BUF_INVALID)
 		return;
 
 	if (buf->flags & TPM_BUF_TPM2B) {
-		dev_err(&chip->dev, "Invalid buffer type (TPM2B)\n");
+		WARN(1, "tpm-buf: invalid type: TPM2B\n");
 		buf->flags |= TPM_BUF_INVALID;
 		return;
 	}
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 254003e5dd8b..e548b0ac7654 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -190,7 +190,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 		tpm_buf_append_name(chip, &buf, pcr_idx, NULL);
 		tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0);
 	} else {
-		tpm_buf_append_handle(chip, &buf, pcr_idx);
+		tpm_buf_append_handle(&buf, pcr_idx);
 		tpm_buf_append_auth(chip, &buf, NULL, 0);
 	}
 
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 13f019d1312a..bbc05f0997a8 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -232,7 +232,7 @@ void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
 #endif
 
 	if (!tpm2_chip_auth(chip)) {
-		tpm_buf_append_handle(chip, buf, handle);
+		tpm_buf_append_handle(buf, handle);
 		return;
 	}
 
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 4613216e9d95..e86c22b30153 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -427,7 +427,7 @@ void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value);
 u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset);
 u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset);
 u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset);
-void tpm_buf_append_handle(struct tpm_chip *chip, struct tpm_buf *buf, u32 handle);
+void tpm_buf_append_handle(struct tpm_buf *buf, u32 handle);
 
 /*
  * Check if TPM device is in the firmware upgrade mode.
-- 
2.39.5


^ permalink raw reply related

* [PATCH v5 9/9] tpm-buf: Enable managed and stack allocations.
From: Jarkko Sakkinen @ 2025-09-30 23:19 UTC (permalink / raw)
  To: linux-integrity
  Cc: dpsmith, ross.philipson, Jarkko Sakkinen, Stefan Berger,
	Peter Huewe, Jarkko Sakkinen, Jason Gunthorpe, David Howells,
	Paul Moore, James Morris, Serge E. Hallyn, James Bottomley,
	Mimi Zohar, open list, open list:KEYS/KEYRINGS,
	open list:SECURITY SUBSYSTEM
In-Reply-To: <20250930231958.1437783-1-jarkko@kernel.org>

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

Decouple kzalloc from buffer creation, so that  a managed allocation can be
done trivially:

	struct tpm_buf *buf __free(kfree) buf = kzalloc(TPM_BUFSIZE,
							GFP_KERNEL);
	if (!buf)
		return -ENOMEM;
	tpm_buf_init(buf, TPM_BUFSIZE);

Alternatively, stack allocations are also possible:

	u8 buf_data[512];
	struct tpm_buf *buf = (struct tpm_buf *)buf_data;
	tpm_buf_init(buf, sizeof(buf_data));

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
---
v5:
- There was a spurious change in tpm2_seal_trusted() error
  code handling introduce by this patch.
v4:
- Since every single tpm_transmit_cmd() call site needs to be
  changed anyhow, use 'dest' parameter more structured and
  actually useful way, and pick the string TCG 1.2 and 2.0
  specifications.
- tpm1-cmd: Remove useless rc declarations and repliace them
  with trivial "return tpm_transmit_cmd" statement.
- Reverted spurious changes in include/linux/tpm.h.
- Use concisely TPM_BUFSIZE instead of PAGE_SIZE.
v3:
- A new patch from the earlier series with more scoped changes and
  less abstract commit message.
---
 drivers/char/tpm/tpm-buf.c                | 122 +++++----
 drivers/char/tpm/tpm-sysfs.c              |  21 +-
 drivers/char/tpm/tpm.h                    |   1 -
 drivers/char/tpm/tpm1-cmd.c               | 162 +++++-------
 drivers/char/tpm/tpm2-cmd.c               | 299 ++++++++++------------
 drivers/char/tpm/tpm2-sessions.c          | 122 +++++----
 drivers/char/tpm/tpm2-space.c             |  44 ++--
 drivers/char/tpm/tpm_vtpm_proxy.c         |  30 +--
 include/linux/tpm.h                       |  18 +-
 security/keys/trusted-keys/trusted_tpm1.c |  34 ++-
 security/keys/trusted-keys/trusted_tpm2.c | 172 ++++++-------
 11 files changed, 484 insertions(+), 541 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index 1b9dee0d0681..a3bf3c3d0c48 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -7,82 +7,109 @@
 #include <linux/module.h>
 #include <linux/tpm.h>
 
-/**
- * tpm_buf_init() - Allocate and initialize a TPM command
- * @buf:	A &tpm_buf
- * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
- * @ordinal:	A command ordinal
- *
- * Return: 0 or -ENOMEM
- */
-int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
+static void __tpm_buf_size_invariant(struct tpm_buf *buf, u16 buf_size)
 {
-	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
-	if (!buf->data)
-		return -ENOMEM;
-
-	tpm_buf_reset(buf, tag, ordinal);
-	return 0;
+	u32 buf_size_2 = (u32)buf->capacity + (u32)sizeof(*buf);
+
+	if (!buf->capacity) {
+		if (buf_size > TPM_BUFSIZE) {
+			WARN(1, "%s: size overflow: %u\n", __func__, buf_size);
+			buf->flags |= TPM_BUF_INVALID;
+		}
+	} else {
+		if (buf_size != buf_size_2) {
+			WARN(1, "%s: size mismatch: %u != %u\n", __func__, buf_size,
+			     buf_size_2);
+			buf->flags |= TPM_BUF_INVALID;
+		}
+	}
 }
-EXPORT_SYMBOL_GPL(tpm_buf_init);
 
-/**
- * tpm_buf_reset() - Initialize a TPM command
- * @buf:	A &tpm_buf
- * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
- * @ordinal:	A command ordinal
- */
-void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
+static void __tpm_buf_reset(struct tpm_buf *buf, u16 buf_size, u16 tag, u32 ordinal)
 {
 	struct tpm_header *head = (struct tpm_header *)buf->data;
 
+	__tpm_buf_size_invariant(buf, buf_size);
+
+	if (buf->flags & TPM_BUF_INVALID)
+		return;
+
 	WARN_ON(tag != TPM_TAG_RQU_COMMAND && tag != TPM2_ST_NO_SESSIONS &&
 		tag != TPM2_ST_SESSIONS && tag != 0);
 
 	buf->flags = 0;
 	buf->length = sizeof(*head);
+	buf->capacity = buf_size - sizeof(*buf);
+	buf->handles = 0;
 	head->tag = cpu_to_be16(tag);
 	head->length = cpu_to_be32(sizeof(*head));
 	head->ordinal = cpu_to_be32(ordinal);
+}
+
+static void __tpm_buf_reset_sized(struct tpm_buf *buf, u16 buf_size)
+{
+	__tpm_buf_size_invariant(buf, buf_size);
+
+	if (buf->flags & TPM_BUF_INVALID)
+		return;
+
+	buf->flags = TPM_BUF_TPM2B;
+	buf->length = 2;
+	buf->capacity = buf_size - sizeof(*buf);
 	buf->handles = 0;
+	buf->data[0] = 0;
+	buf->data[1] = 0;
 }
-EXPORT_SYMBOL_GPL(tpm_buf_reset);
 
 /**
- * tpm_buf_init_sized() - Allocate and initialize a sized (TPM2B) buffer
- * @buf:	A @tpm_buf
- *
- * Return: 0 or -ENOMEM
+ * tpm_buf_init() - Initialize a TPM command
+ * @buf:	A &tpm_buf
+ * @buf_size:	Size of the buffer.
  */
-int tpm_buf_init_sized(struct tpm_buf *buf)
+void tpm_buf_init(struct tpm_buf *buf, u16 buf_size)
 {
-	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
-	if (!buf->data)
-		return -ENOMEM;
+	memset(buf, 0, buf_size);
+	__tpm_buf_reset(buf, buf_size, TPM_TAG_RQU_COMMAND, 0);
+}
+EXPORT_SYMBOL_GPL(tpm_buf_init);
 
-	tpm_buf_reset_sized(buf);
-	return 0;
+/**
+ * tpm_buf_init_sized() - Initialize a sized buffer
+ * @buf:	A &tpm_buf
+ * @buf_size:	Size of the buffer.
+ */
+void tpm_buf_init_sized(struct tpm_buf *buf, u16 buf_size)
+{
+	memset(buf, 0, buf_size);
+	__tpm_buf_reset_sized(buf, buf_size);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_init_sized);
 
 /**
- * tpm_buf_reset_sized() - Initialize a sized buffer
+ * tpm_buf_reset() - Re-initialize a TPM command
  * @buf:	A &tpm_buf
+ * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
+ * @ordinal:	A command ordinal
  */
-void tpm_buf_reset_sized(struct tpm_buf *buf)
+void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
 {
-	buf->flags = TPM_BUF_TPM2B;
-	buf->length = 2;
-	buf->data[0] = 0;
-	buf->data[1] = 0;
+	u16 buf_size = buf->capacity + sizeof(*buf);
+
+	__tpm_buf_reset(buf, buf_size, tag, ordinal);
 }
-EXPORT_SYMBOL_GPL(tpm_buf_reset_sized);
+EXPORT_SYMBOL_GPL(tpm_buf_reset);
 
-void tpm_buf_destroy(struct tpm_buf *buf)
+/**
+ * tpm_buf_reset_sized() - Re-initialize a sized buffer
+ * @buf:	A &tpm_buf
+ */
+void tpm_buf_reset_sized(struct tpm_buf *buf)
 {
-	free_page((unsigned long)buf->data);
+	u16 buf_size = buf->capacity + sizeof(*buf);
+
+	__tpm_buf_reset_sized(buf, buf_size);
 }
-EXPORT_SYMBOL_GPL(tpm_buf_destroy);
+EXPORT_SYMBOL_GPL(tpm_buf_reset_sized);
 
 /**
  * tpm_buf_length() - Return the number of bytes consumed by the data
@@ -92,6 +119,9 @@ EXPORT_SYMBOL_GPL(tpm_buf_destroy);
  */
 u32 tpm_buf_length(struct tpm_buf *buf)
 {
+	if (buf->flags & TPM_BUF_INVALID)
+		return 0;
+
 	return buf->length;
 }
 EXPORT_SYMBOL_GPL(tpm_buf_length);
@@ -104,10 +134,12 @@ EXPORT_SYMBOL_GPL(tpm_buf_length);
  */
 void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
 {
+	u32 total_length = (u32)buf->length + (u32)new_length;
+
 	if (buf->flags & TPM_BUF_INVALID)
 		return;
 
-	if ((buf->length + new_length) > PAGE_SIZE) {
+	if (total_length > (u32)buf->capacity) {
 		WARN(1, "tpm_buf: write overflow\n");
 		buf->flags |= TPM_BUF_INVALID;
 		return;
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 94231f052ea7..f5dcadb1ab3c 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -32,28 +32,29 @@ struct tpm_readpubek_out {
 static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 			  char *buf)
 {
-	struct tpm_buf tpm_buf;
 	struct tpm_readpubek_out *out;
 	int i;
 	char *str = buf;
 	struct tpm_chip *chip = to_tpm_chip(dev);
 	char anti_replay[20];
 
+	struct tpm_buf *tpm_buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!tpm_buf)
+		return -ENOMEM;
+
 	memset(&anti_replay, 0, sizeof(anti_replay));
 
 	if (tpm_try_get_ops(chip))
 		return 0;
 
-	if (tpm_buf_init(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK))
-		goto out_ops;
-
-	tpm_buf_append(&tpm_buf, anti_replay, sizeof(anti_replay));
+	tpm_buf_init(tpm_buf, TPM_BUFSIZE);
+	tpm_buf_reset(tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK);
+	tpm_buf_append(tpm_buf, anti_replay, sizeof(anti_replay));
 
-	if (tpm_transmit_cmd(chip, &tpm_buf, READ_PUBEK_RESULT_MIN_BODY_SIZE,
-			     "attempting to read the PUBEK"))
-		goto out_buf;
+	if (tpm_transmit_cmd(chip, tpm_buf, READ_PUBEK_RESULT_MIN_BODY_SIZE, "TPM_ReadPubek"))
+		goto out_ops;
 
-	out = (struct tpm_readpubek_out *)&tpm_buf.data[10];
+	out = (struct tpm_readpubek_out *)&tpm_buf->data[10];
 	str +=
 	    sprintf(str,
 		    "Algorithm: %4ph\n"
@@ -71,8 +72,6 @@ static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 	for (i = 0; i < 256; i += 16)
 		str += sprintf(str, "%16ph\n", &out->modulus[i]);
 
-out_buf:
-	tpm_buf_destroy(&tpm_buf);
 out_ops:
 	tpm_put_ops(chip);
 	return str - buf;
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 769fa6b00c54..eaff2055b541 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -32,7 +32,6 @@
 #endif
 
 #define TPM_MINOR		224	/* officially assigned */
-#define TPM_BUFSIZE		4096
 #define TPM_NUM_DEVICES		65536
 #define TPM_RETRY		50
 
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 5c49bdff33de..10cb5d008c9f 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -323,20 +323,14 @@ unsigned long tpm1_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
  */
 static int tpm1_startup(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	dev_info(&chip->dev, "starting up the TPM manually\n");
-
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
-	if (rc < 0)
-		return rc;
-
-	tpm_buf_append_u16(&buf, TPM_ST_CLEAR);
-
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to start the TPM");
-	tpm_buf_destroy(&buf);
-	return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
+	tpm_buf_append_u16(buf, TPM_ST_CLEAR);
+	return tpm_transmit_cmd(chip, buf, 0, "TPM_Startup");
 }
 
 int tpm1_get_timeouts(struct tpm_chip *chip)
@@ -463,50 +457,45 @@ int tpm1_get_timeouts(struct tpm_chip *chip)
 int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash,
 		    const char *log_msg)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_EXTEND);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, pcr_idx);
-	tpm_buf_append(&buf, hash, TPM_DIGEST_SIZE);
-
-	rc = tpm_transmit_cmd(chip, &buf, TPM_DIGEST_SIZE, log_msg);
-	tpm_buf_destroy(&buf);
-	return rc;
+	tpm_buf_append_u32(buf, pcr_idx);
+	tpm_buf_append(buf, hash, TPM_DIGEST_SIZE);
+	return tpm_transmit_cmd(chip, buf, TPM_DIGEST_SIZE, log_msg);
 }
 
 #define TPM_ORD_GET_CAP 101
 ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 		    const char *desc, size_t min_cap_length)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
 
 	if (subcap_id == TPM_CAP_VERSION_1_1 ||
 	    subcap_id == TPM_CAP_VERSION_1_2) {
-		tpm_buf_append_u32(&buf, subcap_id);
-		tpm_buf_append_u32(&buf, 0);
+		tpm_buf_append_u32(buf, subcap_id);
+		tpm_buf_append_u32(buf, 0);
 	} else {
 		if (subcap_id == TPM_CAP_FLAG_PERM ||
 		    subcap_id == TPM_CAP_FLAG_VOL)
-			tpm_buf_append_u32(&buf, TPM_CAP_FLAG);
+			tpm_buf_append_u32(buf, TPM_CAP_FLAG);
 		else
-			tpm_buf_append_u32(&buf, TPM_CAP_PROP);
+			tpm_buf_append_u32(buf, TPM_CAP_PROP);
 
-		tpm_buf_append_u32(&buf, 4);
-		tpm_buf_append_u32(&buf, subcap_id);
+		tpm_buf_append_u32(buf, 4);
+		tpm_buf_append_u32(buf, subcap_id);
 	}
-	rc = tpm_transmit_cmd(chip, &buf, min_cap_length, desc);
+	rc = tpm_transmit_cmd(chip, buf, min_cap_length, desc);
 	if (!rc)
-		*cap = *(cap_t *)&buf.data[TPM_HEADER_SIZE + 4];
-	tpm_buf_destroy(&buf);
+		*cap = *(cap_t *)&buf->data[TPM_HEADER_SIZE + 4];
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm1_getcap);
@@ -531,81 +520,69 @@ int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 {
 	struct tpm1_get_random_out *out;
 	u32 num_bytes =  min_t(u32, max, TPM_MAX_RNG_DATA);
-	struct tpm_buf buf;
 	u32 total = 0;
 	int retries = 5;
 	u32 recd;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
+	tpm_buf_init(buf, TPM_BUFSIZE);
 	do {
-		tpm_buf_append_u32(&buf, num_bytes);
+		tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
+		tpm_buf_append_u32(buf, num_bytes);
 
-		rc = tpm_transmit_cmd(chip, &buf, sizeof(out->rng_data_len),
-				      "attempting get random");
+		rc = tpm_transmit_cmd(chip, buf, sizeof(out->rng_data_len), "TPM_GetRandom");
 		if (rc) {
 			if (rc > 0)
 				rc = -EIO;
-			goto out;
+			return rc;
 		}
 
-		out = (struct tpm1_get_random_out *)&buf.data[TPM_HEADER_SIZE];
+		out = (struct tpm1_get_random_out *)&buf->data[TPM_HEADER_SIZE];
 
 		recd = be32_to_cpu(out->rng_data_len);
-		if (recd > num_bytes) {
-			rc = -EFAULT;
-			goto out;
-		}
+		if (recd > num_bytes)
+			return -EFAULT;
+
+		if (buf->length < TPM_HEADER_SIZE +
+				  sizeof(out->rng_data_len) + recd)
+			return -EFAULT;
 
-		if (tpm_buf_length(&buf) < TPM_HEADER_SIZE +
-					   sizeof(out->rng_data_len) + recd) {
-			rc = -EFAULT;
-			goto out;
-		}
 		memcpy(dest, out->rng_data, recd);
 
 		dest += recd;
 		total += recd;
 		num_bytes -= recd;
-
-		tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
 	} while (retries-- && total < max);
 
 	rc = total ? (int)total : -EIO;
-out:
-	tpm_buf_destroy(&buf);
 	return rc;
 }
 
 #define TPM_ORD_PCRREAD 21
 int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCRREAD);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, pcr_idx);
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCRREAD);
+	tpm_buf_append_u32(buf, pcr_idx);
 
-	rc = tpm_transmit_cmd(chip, &buf, TPM_DIGEST_SIZE,
-			      "attempting to read a pcr value");
+	rc = tpm_transmit_cmd(chip, buf, TPM_DIGEST_SIZE, "TPM_PCRRead");
 	if (rc)
-		goto out;
-
-	if (tpm_buf_length(&buf) < TPM_DIGEST_SIZE) {
-		rc = -EFAULT;
-		goto out;
-	}
+		return rc;
 
-	memcpy(res_buf, &buf.data[TPM_HEADER_SIZE], TPM_DIGEST_SIZE);
+	if (buf->length < TPM_DIGEST_SIZE)
+		return -EFAULT;
 
-out:
-	tpm_buf_destroy(&buf);
+	memcpy(res_buf, &buf->data[TPM_HEADER_SIZE], TPM_DIGEST_SIZE);
 	return rc;
 }
 
@@ -619,16 +596,13 @@ int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
  */
 static int tpm1_continue_selftest(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_CONTINUE_SELFTEST);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	rc = tpm_transmit_cmd(chip, &buf, 0, "continue selftest");
-	tpm_buf_destroy(&buf);
-	return rc;
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_CONTINUE_SELFTEST);
+	return tpm_transmit_cmd(chip, buf, 0, "TPM_ContinueSelfTest");
 }
 
 /**
@@ -742,22 +716,24 @@ int tpm1_auto_startup(struct tpm_chip *chip)
 int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 {
 	u8 dummy_hash[TPM_DIGEST_SIZE] = { 0 };
-	struct tpm_buf buf;
 	unsigned int try;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
 	/* for buggy tpm, flush pcrs with extend to selected dummy */
 	if (tpm_suspend_pcr)
 		rc = tpm1_pcr_extend(chip, tpm_suspend_pcr, dummy_hash,
 				     "extending dummy pcr before suspend");
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
-	if (rc)
-		return rc;
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
+
 	/* now do the actual savestate */
 	for (try = 0; try < TPM_RETRY; try++) {
-		rc = tpm_transmit_cmd(chip, &buf, 0, NULL);
+		rc = tpm_transmit_cmd(chip, buf, 0, NULL);
 		/*
 		 * If the TPM indicates that it is too busy to respond to
 		 * this command then retry before giving up.  It can take
@@ -772,7 +748,7 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 			break;
 		tpm_msleep(TPM_TIMEOUT_RETRY);
 
-		tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
+		tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
 	}
 
 	if (rc)
@@ -782,7 +758,5 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 		dev_warn(&chip->dev, "TPM savestate took %dms\n",
 			 try * TPM_TIMEOUT_RETRY);
 
-	tpm_buf_destroy(&buf);
-
 	return rc;
 }
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index e548b0ac7654..768719bbbf04 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -104,12 +104,15 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 {
 	int i;
 	int rc;
-	struct tpm_buf buf;
 	struct tpm2_pcr_read_out *out;
 	u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
 	u16 digest_size;
 	u16 expected_digest_size = 0;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	if (pcr_idx >= TPM2_PLATFORM_PCR)
 		return -EINVAL;
 
@@ -124,36 +127,31 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 		expected_digest_size = chip->allocated_banks[i].digest_size;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
-	if (rc)
-		return rc;
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
 
 	pcr_select[pcr_idx >> 3] = 1 << (pcr_idx & 0x7);
 
-	tpm_buf_append_u32(&buf, 1);
-	tpm_buf_append_u16(&buf, digest->alg_id);
-	tpm_buf_append_u8(&buf, TPM2_PCR_SELECT_MIN);
-	tpm_buf_append(&buf, (const unsigned char *)pcr_select,
+	tpm_buf_append_u32(buf, 1);
+	tpm_buf_append_u16(buf, digest->alg_id);
+	tpm_buf_append_u8(buf, TPM2_PCR_SELECT_MIN);
+	tpm_buf_append(buf, (const unsigned char *)pcr_select,
 		       sizeof(pcr_select));
 
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to read a pcr value");
+	rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_PCR_Read");
 	if (rc)
-		goto out;
+		return rc;
 
-	out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
+	out = (struct tpm2_pcr_read_out *)&buf->data[TPM_HEADER_SIZE];
 	digest_size = be16_to_cpu(out->digest_size);
 	if (digest_size > sizeof(digest->digest) ||
-	    (!digest_size_ptr && digest_size != expected_digest_size)) {
-		rc = -EINVAL;
-		goto out;
-	}
+	    (!digest_size_ptr && digest_size != expected_digest_size))
+		return rc;
 
 	if (digest_size_ptr)
 		*digest_size_ptr = digest_size;
 
 	memcpy(digest->digest, out->digest, digest_size);
-out:
-	tpm_buf_destroy(&buf);
 	return rc;
 }
 
@@ -169,46 +167,45 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 		    struct tpm_digest *digests)
 {
-	struct tpm_buf buf;
 	int rc;
 	int i;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	if (!disable_pcr_integrity) {
 		rc = tpm2_start_auth_session(chip);
 		if (rc)
 			return rc;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
-	if (rc) {
-		if (!disable_pcr_integrity)
-			tpm2_end_auth_session(chip);
-		return rc;
-	}
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
 
 	if (!disable_pcr_integrity) {
-		tpm_buf_append_name(chip, &buf, pcr_idx, NULL);
-		tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0);
+		tpm_buf_append_name(chip, buf, pcr_idx, NULL);
+		tpm_buf_append_hmac_session(chip, buf, 0, NULL, 0);
 	} else {
-		tpm_buf_append_handle(&buf, pcr_idx);
-		tpm_buf_append_auth(chip, &buf, NULL, 0);
+		tpm_buf_append_handle(buf, pcr_idx);
+		tpm_buf_append_auth(chip, buf, NULL, 0);
 	}
 
-	tpm_buf_append_u32(&buf, chip->nr_allocated_banks);
+	tpm_buf_append_u32(buf, chip->nr_allocated_banks);
 
 	for (i = 0; i < chip->nr_allocated_banks; i++) {
-		tpm_buf_append_u16(&buf, digests[i].alg_id);
-		tpm_buf_append(&buf, (const unsigned char *)&digests[i].digest,
+		tpm_buf_append_u16(buf, digests[i].alg_id);
+		tpm_buf_append(buf, (const unsigned char *)&digests[i].digest,
 			       chip->allocated_banks[i].digest_size);
 	}
+	if (buf->flags & TPM_BUF_INVALID)
+		return -EINVAL;
 
 	if (!disable_pcr_integrity)
-		tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting extend a PCR value");
+		tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_PCR_Extend");
 	if (!disable_pcr_integrity)
-		rc = tpm_buf_check_hmac_response(chip, &buf, rc);
-
-	tpm_buf_destroy(&buf);
+		rc = tpm_buf_check_hmac_response(chip, buf, rc);
 
 	return rc;
 }
@@ -233,7 +230,6 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 {
 	struct tpm2_get_random_out *out;
 	struct tpm_header *head;
-	struct tpm_buf buf;
 	u32 recd;
 	u32 num_bytes = max;
 	int err;
@@ -245,51 +241,50 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 	if (!num_bytes || max > TPM_MAX_RNG_DATA)
 		return -EINVAL;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	err = tpm2_start_auth_session(chip);
 	if (err)
 		return err;
 
-	err = tpm_buf_init(&buf, 0, 0);
-	if (err) {
-		tpm2_end_auth_session(chip);
-		return err;
-	}
-
+	tpm_buf_init(buf, TPM_BUFSIZE);
 	do {
-		tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
+		tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
 		if (tpm2_chip_auth(chip)) {
-			tpm_buf_append_hmac_session(chip, &buf,
+			tpm_buf_append_hmac_session(chip, buf,
 						    TPM2_SA_ENCRYPT |
 						    TPM2_SA_CONTINUE_SESSION,
 						    NULL, 0);
 		} else  {
-			offset = buf.handles * 4 + TPM_HEADER_SIZE;
-			head = (struct tpm_header *)buf.data;
-			if (tpm_buf_length(&buf) == offset)
+			offset = buf->handles * 4 + TPM_HEADER_SIZE;
+			head = (struct tpm_header *)buf->data;
+			if (tpm_buf_length(buf) == offset)
 				head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
 		}
-		tpm_buf_append_u16(&buf, num_bytes);
-		tpm_buf_fill_hmac_session(chip, &buf);
-		err = tpm_transmit_cmd(chip, &buf,
+		tpm_buf_append_u16(buf, num_bytes);
+		tpm_buf_fill_hmac_session(chip, buf);
+		err = tpm_transmit_cmd(chip, buf,
 				       offsetof(struct tpm2_get_random_out,
 						buffer),
-				       "attempting get random");
-		err = tpm_buf_check_hmac_response(chip, &buf, err);
+				       "TPM2_GetRandom");
+		err = tpm_buf_check_hmac_response(chip, buf, err);
 		if (err) {
 			if (err > 0)
 				err = -EIO;
 			goto out;
 		}
 
-		head = (struct tpm_header *)buf.data;
+		head = (struct tpm_header *)buf->data;
 		offset = TPM_HEADER_SIZE;
 		/* Skip the parameter size field: */
 		if (be16_to_cpu(head->tag) == TPM2_ST_SESSIONS)
 			offset += 4;
 
-		out = (struct tpm2_get_random_out *)&buf.data[offset];
+		out = (struct tpm2_get_random_out *)&buf->data[offset];
 		recd = min_t(u32, be16_to_cpu(out->size), num_bytes);
-		if (tpm_buf_length(&buf) <
+		if (tpm_buf_length(buf) <
 		    TPM_HEADER_SIZE +
 		    offsetof(struct tpm2_get_random_out, buffer) +
 		    recd) {
@@ -303,11 +298,9 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 		num_bytes -= recd;
 	} while (retries-- && total < max);
 
-	tpm_buf_destroy(&buf);
-
 	return total ? total : -EIO;
+
 out:
-	tpm_buf_destroy(&buf);
 	tpm2_end_auth_session(chip);
 	return err;
 }
@@ -319,20 +312,18 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
  */
 void tpm2_flush_context(struct tpm_chip *chip, u32 handle)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_FLUSH_CONTEXT);
-	if (rc) {
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf) {
 		dev_warn(&chip->dev, "0x%08x was not flushed, out of memory\n",
 			 handle);
 		return;
 	}
 
-	tpm_buf_append_u32(&buf, handle);
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_FLUSH_CONTEXT);
+	tpm_buf_append_u32(buf, handle);
 
-	tpm_transmit_cmd(chip, &buf, 0, "flushing context");
-	tpm_buf_destroy(&buf);
+	tpm_transmit_cmd(chip, buf, 0, "TPM2_FlushContext");
 }
 EXPORT_SYMBOL_GPL(tpm2_flush_context);
 
@@ -359,19 +350,20 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
 			const char *desc)
 {
 	struct tpm2_get_cap_out *out;
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		return rc;
-	tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
-	tpm_buf_append_u32(&buf, property_id);
-	tpm_buf_append_u32(&buf, 1);
-	rc = tpm_transmit_cmd(chip, &buf, 0, NULL);
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_TPM_PROPERTIES);
+	tpm_buf_append_u32(buf, property_id);
+	tpm_buf_append_u32(buf, 1);
+	rc = tpm_transmit_cmd(chip, buf, 0, NULL);
 	if (!rc) {
-		out = (struct tpm2_get_cap_out *)
-			&buf.data[TPM_HEADER_SIZE];
+		out = (struct tpm2_get_cap_out *)&buf->data[TPM_HEADER_SIZE];
 		/*
 		 * To prevent failing boot up of some systems, Infineon TPM2.0
 		 * returns SUCCESS on TPM2_Startup in field upgrade mode. Also
@@ -383,7 +375,6 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
 		else
 			rc = -ENODATA;
 	}
-	tpm_buf_destroy(&buf);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm2_get_tpm_pt);
@@ -400,15 +391,14 @@ EXPORT_SYMBOL_GPL(tpm2_get_tpm_pt);
  */
 void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SHUTDOWN);
-	if (rc)
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
 		return;
-	tpm_buf_append_u16(&buf, shutdown_type);
-	tpm_transmit_cmd(chip, &buf, 0, "stopping the TPM");
-	tpm_buf_destroy(&buf);
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SHUTDOWN);
+	tpm_buf_append_u16(buf, shutdown_type);
+	tpm_transmit_cmd(chip, buf, 0, "TPM2_Shutdown");
 }
 
 /**
@@ -426,20 +416,19 @@ void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type)
  */
 static int tpm2_do_selftest(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
 	int full;
 	int rc;
 
-	for (full = 0; full < 2; full++) {
-		rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
-		if (rc)
-			return rc;
-
-		tpm_buf_append_u8(&buf, full);
-		rc = tpm_transmit_cmd(chip, &buf, 0,
-				      "attempting the self test");
-		tpm_buf_destroy(&buf);
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
+	for (full = 0; full < 2; full++) {
+		tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
+		tpm_buf_append_u8(buf, full);
+		rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_SelfTest");
 		if (rc == TPM2_RC_TESTING)
 			rc = TPM2_RC_SUCCESS;
 		if (rc == TPM2_RC_INITIALIZE || rc == TPM2_RC_SUCCESS)
@@ -464,23 +453,24 @@ static int tpm2_do_selftest(struct tpm_chip *chip)
 int tpm2_probe(struct tpm_chip *chip)
 {
 	struct tpm_header *out;
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		return rc;
-	tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
-	tpm_buf_append_u32(&buf, TPM_PT_TOTAL_COMMANDS);
-	tpm_buf_append_u32(&buf, 1);
-	rc = tpm_transmit_cmd(chip, &buf, 0, NULL);
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_TPM_PROPERTIES);
+	tpm_buf_append_u32(buf, TPM_PT_TOTAL_COMMANDS);
+	tpm_buf_append_u32(buf, 1);
+	rc = tpm_transmit_cmd(chip, buf, 0, NULL);
 	/* We ignore TPM return codes on purpose. */
 	if (rc >=  0) {
-		out = (struct tpm_header *)buf.data;
+		out = (struct tpm_header *)buf->data;
 		if (be16_to_cpu(out->tag) == TPM2_ST_NO_SESSIONS)
 			chip->flags |= TPM_CHIP_FLAG_TPM2;
 	}
-	tpm_buf_destroy(&buf);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tpm2_probe);
@@ -520,7 +510,6 @@ struct tpm2_pcr_selection {
 ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 {
 	struct tpm2_pcr_selection pcr_selection;
-	struct tpm_buf buf;
 	void *marker;
 	void *end;
 	void *pcr_select_offset;
@@ -532,39 +521,37 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	int rc;
 	int i = 0;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, TPM2_CAP_PCRS);
-	tpm_buf_append_u32(&buf, 0);
-	tpm_buf_append_u32(&buf, 1);
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_PCRS);
+	tpm_buf_append_u32(buf, 0);
+	tpm_buf_append_u32(buf, 1);
 
-	rc = tpm_transmit_cmd(chip, &buf, 9, "get tpm pcr allocation");
+	rc = tpm_transmit_cmd(chip, buf, 9, "TPM2_GetCapability(PCRS)");
 	if (rc)
-		goto out;
+		return rc;
 
-	nr_possible_banks = be32_to_cpup(
-		(__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
+	nr_possible_banks = be32_to_cpup((__be32 *)&buf->data[TPM_HEADER_SIZE + 5]);
 	if (nr_possible_banks > TPM2_MAX_PCR_BANKS) {
 		pr_err("tpm: unexpected number of banks: %u > %u",
 		       nr_possible_banks, TPM2_MAX_PCR_BANKS);
-		rc = -ENOMEM;
-		goto out;
+		return -ENOMEM;
 	}
 
-	marker = &buf.data[TPM_HEADER_SIZE + 9];
+	marker = &buf->data[TPM_HEADER_SIZE + 9];
 
-	rsp_len = be32_to_cpup((__be32 *)&buf.data[2]);
-	end = &buf.data[rsp_len];
+	rsp_len = be32_to_cpup((__be32 *)&buf->data[2]);
+	end = &buf->data[rsp_len];
 
 	for (i = 0; i < nr_possible_banks; i++) {
 		pcr_select_offset = marker +
 			offsetof(struct tpm2_pcr_selection, size_of_select);
-		if (pcr_select_offset >= end) {
-			rc = -EFAULT;
-			break;
-		}
+		if (pcr_select_offset >= end)
+			return -EFAULT;
 
 		memcpy(&pcr_selection, marker, sizeof(pcr_selection));
 		hash_alg = be16_to_cpu(pcr_selection.hash_alg);
@@ -576,7 +563,7 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 
 			rc = tpm2_init_bank_info(chip, nr_alloc_banks);
 			if (rc < 0)
-				break;
+				return rc;
 
 			nr_alloc_banks++;
 		}
@@ -588,21 +575,21 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	}
 
 	chip->nr_allocated_banks = nr_alloc_banks;
-out:
-	tpm_buf_destroy(&buf);
-
-	return rc;
+	return 0;
 }
 
 int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
 	u32 nr_commands;
 	__be32 *attrs;
 	u32 cc;
 	int i;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	rc = tpm2_get_tpm_pt(chip, TPM_PT_TOTAL_COMMANDS, &nr_commands, NULL);
 	if (rc)
 		goto out;
@@ -619,30 +606,24 @@ int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 		goto out;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		goto out;
-
-	tpm_buf_append_u32(&buf, TPM2_CAP_COMMANDS);
-	tpm_buf_append_u32(&buf, TPM2_CC_FIRST);
-	tpm_buf_append_u32(&buf, nr_commands);
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_COMMANDS);
+	tpm_buf_append_u32(buf, TPM2_CC_FIRST);
+	tpm_buf_append_u32(buf, nr_commands);
 
-	rc = tpm_transmit_cmd(chip, &buf, 9 + 4 * nr_commands, NULL);
-	if (rc) {
-		tpm_buf_destroy(&buf);
+	rc = tpm_transmit_cmd(chip, buf, 9 + 4 * nr_commands, NULL);
+	if (rc)
 		goto out;
-	}
 
-	if (nr_commands !=
-	    be32_to_cpup((__be32 *)&buf.data[TPM_HEADER_SIZE + 5])) {
+	if (nr_commands != be32_to_cpup((__be32 *)&buf->data[TPM_HEADER_SIZE + 5])) {
 		rc = -EFAULT;
-		tpm_buf_destroy(&buf);
 		goto out;
 	}
 
 	chip->nr_commands = nr_commands;
 
-	attrs = (__be32 *)&buf.data[TPM_HEADER_SIZE + 9];
+	attrs = (__be32 *)&buf->data[TPM_HEADER_SIZE + 9];
 	for (i = 0; i < nr_commands; i++, attrs++) {
 		chip->cc_attrs_tbl[i] = be32_to_cpup(attrs);
 		cc = chip->cc_attrs_tbl[i] & 0xFFFF;
@@ -654,8 +635,6 @@ int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 		}
 	}
 
-	tpm_buf_destroy(&buf);
-
 out:
 	if (rc > 0)
 		rc = -ENODEV;
@@ -676,20 +655,14 @@ EXPORT_SYMBOL_GPL(tpm2_get_cc_attrs_tbl);
 
 static int tpm2_startup(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	dev_info(&chip->dev, "starting up the TPM manually\n");
-
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_STARTUP);
-	if (rc < 0)
-		return rc;
-
-	tpm_buf_append_u16(&buf, TPM2_SU_CLEAR);
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to start the TPM");
-	tpm_buf_destroy(&buf);
-
-	return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_STARTUP);
+	tpm_buf_append_u16(buf, TPM2_SU_CLEAR);
+	return tpm_transmit_cmd(chip, buf, 0, "TPM2_Startup");
 }
 
 /**
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index bbc05f0997a8..378b8d21b10c 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -182,19 +182,18 @@ static int tpm2_parse_read_public(char *name, struct tpm_buf *buf)
 
 static int tpm2_read_public(struct tpm_chip *chip, u32 handle, char *name)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, handle);
-	rc = tpm_transmit_cmd(chip, &buf, 0, "read public");
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
+	tpm_buf_append_u32(buf, handle);
+	rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_ReadPublic");
 	if (rc == TPM2_RC_SUCCESS)
-		rc = tpm2_parse_read_public(name, &buf);
-
-	tpm_buf_destroy(&buf);
+		rc = tpm2_parse_read_public(name, buf);
 
 	return rc;
 }
@@ -924,7 +923,6 @@ static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key)
 int tpm2_start_auth_session(struct tpm_chip *chip)
 {
 	struct tpm2_auth *auth;
-	struct tpm_buf buf;
 	u32 null_key;
 	int rc;
 
@@ -933,6 +931,10 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
 		return 0;
 	}
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	auth = kzalloc(sizeof(*auth), GFP_KERNEL);
 	if (!auth)
 		return -ENOMEM;
@@ -943,41 +945,37 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
 
 	auth->session = TPM_HEADER_SIZE;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_START_AUTH_SESS);
-	if (rc)
-		goto out;
-
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_START_AUTH_SESS);
 	/* salt key handle */
-	tpm_buf_append_u32(&buf, null_key);
+	tpm_buf_append_u32(buf, null_key);
 	/* bind key handle */
-	tpm_buf_append_u32(&buf, TPM2_RH_NULL);
+	tpm_buf_append_u32(buf, TPM2_RH_NULL);
 	/* nonce caller */
 	get_random_bytes(auth->our_nonce, sizeof(auth->our_nonce));
-	tpm_buf_append_u16(&buf, sizeof(auth->our_nonce));
-	tpm_buf_append(&buf, auth->our_nonce, sizeof(auth->our_nonce));
+	tpm_buf_append_u16(buf, sizeof(auth->our_nonce));
+	tpm_buf_append(buf, auth->our_nonce, sizeof(auth->our_nonce));
 
 	/* append encrypted salt and squirrel away unencrypted in auth */
-	tpm_buf_append_salt(&buf, chip, auth);
+	tpm_buf_append_salt(buf, chip, auth);
 	/* session type (HMAC, audit or policy) */
-	tpm_buf_append_u8(&buf, TPM2_SE_HMAC);
+	tpm_buf_append_u8(buf, TPM2_SE_HMAC);
 
 	/* symmetric encryption parameters */
 	/* symmetric algorithm */
-	tpm_buf_append_u16(&buf, TPM_ALG_AES);
+	tpm_buf_append_u16(buf, TPM_ALG_AES);
 	/* bits for symmetric algorithm */
-	tpm_buf_append_u16(&buf, AES_KEY_BITS);
+	tpm_buf_append_u16(buf, AES_KEY_BITS);
 	/* symmetric algorithm mode (must be CFB) */
-	tpm_buf_append_u16(&buf, TPM_ALG_CFB);
+	tpm_buf_append_u16(buf, TPM_ALG_CFB);
 	/* hash algorithm for session */
-	tpm_buf_append_u16(&buf, TPM_ALG_SHA256);
+	tpm_buf_append_u16(buf, TPM_ALG_SHA256);
 
-	rc = tpm_ret_to_err(tpm_transmit_cmd(chip, &buf, 0, "StartAuthSession"));
+	rc = tpm_ret_to_err(tpm_transmit_cmd(chip, buf, 0, "TPM2_StartAuthSession"));
 	tpm2_flush_context(chip, null_key);
 
 	if (rc == TPM2_RC_SUCCESS)
-		rc = tpm2_parse_start_auth_session(auth, &buf);
-
-	tpm_buf_destroy(&buf);
+		rc = tpm2_parse_start_auth_session(auth, buf);
 
 	if (rc == TPM2_RC_SUCCESS) {
 		chip->auth = auth;
@@ -1199,18 +1197,18 @@ static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy,
 			       u32 *handle, u8 *name)
 {
 	int rc;
-	struct tpm_buf buf;
-	struct tpm_buf template;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE_PRIMARY);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	rc = tpm_buf_init_sized(&template);
-	if (rc) {
-		tpm_buf_destroy(&buf);
-		return rc;
-	}
+	struct tpm_buf *template __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!template)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE_PRIMARY);
+	tpm_buf_init_sized(template, TPM_BUFSIZE);
 
 	/*
 	 * create the template.  Note: in order for userspace to
@@ -1222,75 +1220,71 @@ static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy,
 	 */
 
 	/* key type */
-	tpm_buf_append_u16(&template, TPM_ALG_ECC);
+	tpm_buf_append_u16(template, TPM_ALG_ECC);
 
 	/* name algorithm */
-	tpm_buf_append_u16(&template, TPM_ALG_SHA256);
+	tpm_buf_append_u16(template, TPM_ALG_SHA256);
 
 	/* object properties */
-	tpm_buf_append_u32(&template, TPM2_OA_NULL_KEY);
+	tpm_buf_append_u32(template, TPM2_OA_NULL_KEY);
 
 	/* sauth policy (empty) */
-	tpm_buf_append_u16(&template, 0);
+	tpm_buf_append_u16(template, 0);
 
 	/* BEGIN parameters: key specific; for ECC*/
 
 	/* symmetric algorithm */
-	tpm_buf_append_u16(&template, TPM_ALG_AES);
+	tpm_buf_append_u16(template, TPM_ALG_AES);
 
 	/* bits for symmetric algorithm */
-	tpm_buf_append_u16(&template, AES_KEY_BITS);
+	tpm_buf_append_u16(template, AES_KEY_BITS);
 
 	/* algorithm mode (must be CFB) */
-	tpm_buf_append_u16(&template, TPM_ALG_CFB);
+	tpm_buf_append_u16(template, TPM_ALG_CFB);
 
 	/* scheme (NULL means any scheme) */
-	tpm_buf_append_u16(&template, TPM_ALG_NULL);
+	tpm_buf_append_u16(template, TPM_ALG_NULL);
 
 	/* ECC Curve ID */
-	tpm_buf_append_u16(&template, TPM2_ECC_NIST_P256);
+	tpm_buf_append_u16(template, TPM2_ECC_NIST_P256);
 
 	/* KDF Scheme */
-	tpm_buf_append_u16(&template, TPM_ALG_NULL);
+	tpm_buf_append_u16(template, TPM_ALG_NULL);
 
 	/* unique: key specific; for ECC it is two zero size points */
-	tpm_buf_append_u16(&template, 0);
-	tpm_buf_append_u16(&template, 0);
+	tpm_buf_append_u16(template, 0);
+	tpm_buf_append_u16(template, 0);
 
 	/* END parameters */
 
 	/* primary handle */
-	tpm_buf_append_u32(&buf, hierarchy);
-	tpm_buf_append_empty_auth(&buf, TPM2_RS_PW);
+	tpm_buf_append_u32(buf, hierarchy);
+	tpm_buf_append_empty_auth(buf, TPM2_RS_PW);
 
 	/* sensitive create size is 4 for two empty buffers */
-	tpm_buf_append_u16(&buf, 4);
+	tpm_buf_append_u16(buf, 4);
 
 	/* sensitive create auth data (empty) */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* sensitive create sensitive data (empty) */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* the public template */
-	tpm_buf_append(&buf, template.data, template.length);
-	tpm_buf_destroy(&template);
+	tpm_buf_append(buf, template->data, template->length);
 
 	/* outside info (empty) */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* creation PCR (none) */
-	tpm_buf_append_u32(&buf, 0);
+	tpm_buf_append_u32(buf, 0);
 
-	rc = tpm_transmit_cmd(chip, &buf, 0,
-			      "attempting to create NULL primary");
+	rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_CreatePrimary");
 
 	if (rc == TPM2_RC_SUCCESS)
-		rc = tpm2_parse_create_primary(chip, &buf, handle, hierarchy,
+		rc = tpm2_parse_create_primary(chip, buf, handle, hierarchy,
 					       name);
 
-	tpm_buf_destroy(&buf);
-
 	return rc;
 }
 
diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index 0ad5e18355e0..4229c71940cb 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -70,24 +70,25 @@ void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space)
 int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
 		      unsigned int *offset, u32 *handle)
 {
-	struct tpm_buf tbuf;
 	struct tpm2_context *ctx;
 	unsigned int body_size;
 	int rc;
 
-	rc = tpm_buf_init(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_LOAD);
-	if (rc)
-		return rc;
+	struct tpm_buf *tbuf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
+
+	tpm_buf_init(tbuf, TPM_BUFSIZE);
+	tpm_buf_reset(tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_LOAD);
 
 	ctx = (struct tpm2_context *)&buf[*offset];
 	body_size = sizeof(*ctx) + be16_to_cpu(ctx->blob_size);
-	tpm_buf_append(&tbuf, &buf[*offset], body_size);
+	tpm_buf_append(tbuf, &buf[*offset], body_size);
 
-	rc = tpm_transmit_cmd(chip, &tbuf, 4, NULL);
+	rc = tpm_transmit_cmd(chip, tbuf, 4, NULL);
 	if (rc < 0) {
 		dev_warn(&chip->dev, "%s: failed with a system error %d\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	} else if (tpm2_rc_value(rc) == TPM2_RC_HANDLE ||
 		   rc == TPM2_RC_REFERENCE_H0) {
@@ -102,64 +103,55 @@ int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
 		 * flushed outside the space
 		 */
 		*handle = 0;
-		tpm_buf_destroy(&tbuf);
 		return -ENOENT;
 	} else if (tpm2_rc_value(rc) == TPM2_RC_INTEGRITY) {
-		tpm_buf_destroy(&tbuf);
 		return -EINVAL;
 	} else if (rc > 0) {
 		dev_warn(&chip->dev, "%s: failed with a TPM error 0x%04X\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	}
 
-	*handle = be32_to_cpup((__be32 *)&tbuf.data[TPM_HEADER_SIZE]);
+	*handle = be32_to_cpup((__be32 *)&tbuf->data[TPM_HEADER_SIZE]);
 	*offset += body_size;
-
-	tpm_buf_destroy(&tbuf);
 	return 0;
 }
 
 int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf,
 		      unsigned int buf_size, unsigned int *offset)
 {
-	struct tpm_buf tbuf;
 	unsigned int body_size;
 	int rc;
 
-	rc = tpm_buf_init(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_SAVE);
-	if (rc)
-		return rc;
+	struct tpm_buf *tbuf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&tbuf, handle);
+	tpm_buf_init(tbuf, TPM_BUFSIZE);
+	tpm_buf_reset(tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_SAVE);
+	tpm_buf_append_u32(tbuf, handle);
 
-	rc = tpm_transmit_cmd(chip, &tbuf, 0, NULL);
+	rc = tpm_transmit_cmd(chip, tbuf, 0, NULL);
 	if (rc < 0) {
 		dev_warn(&chip->dev, "%s: failed with a system error %d\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	} else if (tpm2_rc_value(rc) == TPM2_RC_REFERENCE_H0) {
-		tpm_buf_destroy(&tbuf);
 		return -ENOENT;
 	} else if (rc) {
 		dev_warn(&chip->dev, "%s: failed with a TPM error 0x%04X\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	}
 
-	body_size = tpm_buf_length(&tbuf) - TPM_HEADER_SIZE;
+	body_size = tpm_buf_length(tbuf) - TPM_HEADER_SIZE;
 	if ((*offset + body_size) > buf_size) {
 		dev_warn(&chip->dev, "%s: out of backing storage\n", __func__);
-		tpm_buf_destroy(&tbuf);
 		return -ENOMEM;
 	}
 
-	memcpy(&buf[*offset], &tbuf.data[TPM_HEADER_SIZE], body_size);
+	memcpy(&buf[*offset], &tbuf->data[TPM_HEADER_SIZE], body_size);
 	*offset += body_size;
-	tpm_buf_destroy(&tbuf);
 	return 0;
 }
 
diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
index 0818bb517805..682dfc93845d 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -395,40 +395,36 @@ static bool vtpm_proxy_tpm_req_canceled(struct tpm_chip  *chip, u8 status)
 
 static int vtpm_proxy_request_locality(struct tpm_chip *chip, int locality)
 {
-	struct tpm_buf buf;
 	int rc;
 	const struct tpm_header *header;
 	struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev);
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_init(buf, TPM_BUFSIZE);
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
-		rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS,
-				  TPM2_CC_SET_LOCALITY);
+		tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_SET_LOCALITY);
 	else
-		rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND,
-				  TPM_ORD_SET_LOCALITY);
-	if (rc)
-		return rc;
-	tpm_buf_append_u8(&buf, locality);
+		tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SET_LOCALITY);
+
+	tpm_buf_append_u8(buf, locality);
 
 	proxy_dev->state |= STATE_DRIVER_COMMAND;
 
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to set locality");
+	rc = tpm_transmit_cmd(chip, buf, 0, "attempting to set locality");
 
 	proxy_dev->state &= ~STATE_DRIVER_COMMAND;
 
-	if (rc < 0) {
-		locality = rc;
-		goto out;
-	}
+	if (rc < 0)
+		return rc;
 
-	header = (const struct tpm_header *)buf.data;
+	header = (const struct tpm_header *)buf->data;
 	rc = be32_to_cpu(header->return_code);
 	if (rc)
 		locality = -1;
 
-out:
-	tpm_buf_destroy(&buf);
-
 	return locality;
 }
 
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index e86c22b30153..2ea181a35786 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -26,7 +26,8 @@
 #include <crypto/hash_info.h>
 #include <crypto/aes.h>
 
-#define TPM_DIGEST_SIZE 20	/* Max TPM v1.2 PCR size */
+#define TPM_DIGEST_SIZE		20	/* Max TPM v1.2 PCR size */
+#define TPM_BUFSIZE		4096
 
 #define TPM2_MAX_DIGEST_SIZE	SHA512_DIGEST_SIZE
 #define TPM2_MAX_PCR_BANKS	8
@@ -377,13 +378,15 @@ enum tpm_buf_flags {
 };
 
 /*
- * A string buffer type for constructing TPM commands.
+ * A buffer for constructing and parsing TPM commands, responses and sized
+ * (TPM2B) buffers.
  */
 struct tpm_buf {
-	u32 flags;
-	u32 length;
-	u8 *data;
+	u8 flags;
 	u8 handles;
+	u16 length;
+	u16 capacity;
+	u8 data[];
 };
 
 enum tpm2_object_attributes {
@@ -414,11 +417,10 @@ struct tpm2_hash {
 	unsigned int tpm_id;
 };
 
-int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal);
+void tpm_buf_init(struct tpm_buf *buf, u16 buf_size);
+void tpm_buf_init_sized(struct tpm_buf *buf, u16 buf_size);
 void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal);
-int tpm_buf_init_sized(struct tpm_buf *buf);
 void tpm_buf_reset_sized(struct tpm_buf *buf);
-void tpm_buf_destroy(struct tpm_buf *buf);
 u32 tpm_buf_length(struct tpm_buf *buf);
 void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length);
 void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value);
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index 636acb66a4f6..3ac204a902de 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -310,9 +310,8 @@ static int TSS_checkhmac2(unsigned char *buffer,
  * For key specific tpm requests, we will generate and send our
  * own TPM command packets using the drivers send function.
  */
-static int trusted_tpm_send(unsigned char *cmd, size_t buflen)
+static int trusted_tpm_send(void *cmd, size_t buflen)
 {
-	struct tpm_buf buf;
 	int rc;
 
 	if (!chip)
@@ -322,15 +321,12 @@ static int trusted_tpm_send(unsigned char *cmd, size_t buflen)
 	if (rc)
 		return rc;
 
-	buf.flags = 0;
-	buf.length = buflen;
-	buf.data = cmd;
 	dump_tpm_buf(cmd);
-	rc = tpm_transmit_cmd(chip, &buf, 4, "sending data");
+	rc = tpm_transmit_cmd(chip, cmd, 4, "sending data");
 	dump_tpm_buf(cmd);
 
+	/* Convert TPM error to -EPERM. */
 	if (rc > 0)
-		/* TPM error */
 		rc = -EPERM;
 
 	tpm_put_ops(chip);
@@ -624,23 +620,23 @@ static int tpm_unseal(struct tpm_buf *tb,
 static int key_seal(struct trusted_key_payload *p,
 		    struct trusted_key_options *o)
 {
-	struct tpm_buf tb;
 	int ret;
 
-	ret = tpm_buf_init(&tb, 0, 0);
-	if (ret)
-		return ret;
+	struct tpm_buf *tb __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!tb)
+		return -ENOMEM;
+
+	tpm_buf_init(tb, TPM_BUFSIZE);
 
 	/* include migratable flag at end of sealed key */
 	p->key[p->key_len] = p->migratable;
 
-	ret = tpm_seal(&tb, o->keytype, o->keyhandle, o->keyauth,
+	ret = tpm_seal(tb, o->keytype, o->keyhandle, o->keyauth,
 		       p->key, p->key_len + 1, p->blob, &p->blob_len,
 		       o->blobauth, o->pcrinfo, o->pcrinfo_len);
 	if (ret < 0)
 		pr_info("srkseal failed (%d)\n", ret);
 
-	tpm_buf_destroy(&tb);
 	return ret;
 }
 
@@ -650,14 +646,15 @@ static int key_seal(struct trusted_key_payload *p,
 static int key_unseal(struct trusted_key_payload *p,
 		      struct trusted_key_options *o)
 {
-	struct tpm_buf tb;
 	int ret;
 
-	ret = tpm_buf_init(&tb, 0, 0);
-	if (ret)
-		return ret;
+	struct tpm_buf *tb __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!tb)
+		return -ENOMEM;
+
+	tpm_buf_init(tb, TPM_BUFSIZE);
 
-	ret = tpm_unseal(&tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
+	ret = tpm_unseal(tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
 			 o->blobauth, p->key, &p->key_len);
 	if (ret < 0)
 		pr_info("srkunseal failed (%d)\n", ret);
@@ -665,7 +662,6 @@ static int key_unseal(struct trusted_key_payload *p,
 		/* pull migratable flag out of sealed key */
 		p->migratable = p->key[--p->key_len];
 
-	tpm_buf_destroy(&tb);
 	return ret;
 }
 
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 119d5152c0db..71a3674b495a 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -212,13 +212,20 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		      struct trusted_key_options *options)
 {
 	off_t offset = TPM_HEADER_SIZE;
-	struct tpm_buf buf, sized;
 	int blob_len = 0;
 	u32 hash;
 	u32 flags;
 	int i;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	struct tpm_buf *sized __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!sized)
+		return -ENOMEM;
+
 	for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) {
 		if (options->hash == tpm2_hash_map[i].crypto_id) {
 			hash = tpm2_hash_map[i].tpm_id;
@@ -240,91 +247,79 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	if (rc)
 		goto out_put;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
-	if (rc) {
-		tpm2_end_auth_session(chip);
-		goto out_put;
-	}
-
-	rc = tpm_buf_init_sized(&sized);
-	if (rc) {
-		tpm_buf_destroy(&buf);
-		tpm2_end_auth_session(chip);
-		goto out_put;
-	}
-
-	tpm_buf_append_name(chip, &buf, options->keyhandle, NULL);
-	tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT,
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_init_sized(sized, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
+	tpm_buf_append_name(chip, buf, options->keyhandle, NULL);
+	tpm_buf_append_hmac_session(chip, buf, TPM2_SA_DECRYPT,
 				    options->keyauth, TPM_DIGEST_SIZE);
 
 	/* sensitive */
-	tpm_buf_append_u16(&sized, options->blobauth_len);
+	tpm_buf_append_u16(sized, options->blobauth_len);
 
 	if (options->blobauth_len)
-		tpm_buf_append(&sized, options->blobauth, options->blobauth_len);
+		tpm_buf_append(sized, options->blobauth, options->blobauth_len);
 
-	tpm_buf_append_u16(&sized, payload->key_len);
-	tpm_buf_append(&sized, payload->key, payload->key_len);
-	tpm_buf_append(&buf, sized.data, sized.length);
+	tpm_buf_append_u16(sized, payload->key_len);
+	tpm_buf_append(sized, payload->key, payload->key_len);
+	tpm_buf_append(buf, sized->data, sized->length);
 
 	/* public */
-	tpm_buf_reset_sized(&sized);
-	tpm_buf_append_u16(&sized, TPM_ALG_KEYEDHASH);
-	tpm_buf_append_u16(&sized, hash);
+	tpm_buf_init_sized(sized, TPM_BUFSIZE);
+	tpm_buf_append_u16(sized, TPM_ALG_KEYEDHASH);
+	tpm_buf_append_u16(sized, hash);
 
 	/* key properties */
 	flags = 0;
 	flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH;
 	flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT);
-	tpm_buf_append_u32(&sized, flags);
+	tpm_buf_append_u32(sized, flags);
 
 	/* policy */
-	tpm_buf_append_u16(&sized, options->policydigest_len);
+	tpm_buf_append_u16(sized, options->policydigest_len);
 	if (options->policydigest_len)
-		tpm_buf_append(&sized, options->policydigest, options->policydigest_len);
+		tpm_buf_append(sized, options->policydigest, options->policydigest_len);
 
 	/* public parameters */
-	tpm_buf_append_u16(&sized, TPM_ALG_NULL);
-	tpm_buf_append_u16(&sized, 0);
+	tpm_buf_append_u16(sized, TPM_ALG_NULL);
+	tpm_buf_append_u16(sized, 0);
 
-	tpm_buf_append(&buf, sized.data, sized.length);
+	tpm_buf_append(buf, sized->data, sized->length);
 
 	/* outside info */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* creation PCR */
-	tpm_buf_append_u32(&buf, 0);
+	tpm_buf_append_u32(buf, 0);
 
-	if (buf.flags & TPM_BUF_INVALID) {
+	if (buf->flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		tpm2_end_auth_session(chip);
 		goto out;
 	}
 
-	tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data");
-	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+	tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 4, "sealing data");
+	rc = tpm_buf_check_hmac_response(chip, buf, rc);
 	if (rc)
 		goto out;
 
-	blob_len = tpm_buf_read_u32(&buf, &offset);
-	if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_INVALID) {
+	blob_len = tpm_buf_read_u32(buf, &offset);
+	if (blob_len > MAX_BLOB_SIZE || buf->flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		goto out;
 	}
-	if (buf.length - offset < blob_len) {
+	if (buf->length - offset < blob_len) {
 		rc = -EFAULT;
 		goto out;
 	}
 
-	blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
+	blob_len = tpm2_key_encode(payload, options, &buf->data[offset],
+				   blob_len);
 	if (blob_len < 0)
 		rc = blob_len;
 
 out:
-	tpm_buf_destroy(&sized);
-	tpm_buf_destroy(&buf);
-
 	if (!rc)
 		payload->blob_len = blob_len;
 
@@ -351,7 +346,6 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 			 struct trusted_key_options *options,
 			 u32 *blob_handle)
 {
-	struct tpm_buf buf;
 	unsigned int private_len;
 	unsigned int public_len;
 	unsigned int blob_len;
@@ -359,6 +353,10 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	int rc;
 	u32 attrs;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	rc = tpm2_key_decode(payload, options, &blob);
 	if (rc) {
 		/* old form */
@@ -402,35 +400,30 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	if (rc)
 		return rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
-	if (rc) {
-		tpm2_end_auth_session(chip);
-		return rc;
-	}
-
-	tpm_buf_append_name(chip, &buf, options->keyhandle, NULL);
-	tpm_buf_append_hmac_session(chip, &buf, 0, options->keyauth,
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
+	tpm_buf_append_name(chip, buf, options->keyhandle, NULL);
+	tpm_buf_append_hmac_session(chip, buf, 0, options->keyauth,
 				    TPM_DIGEST_SIZE);
 
-	tpm_buf_append(&buf, blob, blob_len);
+	tpm_buf_append(buf, blob, blob_len);
 
-	if (buf.flags & TPM_BUF_INVALID) {
+	if (buf->flags & TPM_BUF_INVALID) {
 		rc = -E2BIG;
 		tpm2_end_auth_session(chip);
 		goto out;
 	}
 
-	tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob");
-	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+	tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 4, "loading blob");
+	rc = tpm_buf_check_hmac_response(chip, buf, rc);
 	if (!rc)
 		*blob_handle = be32_to_cpup(
-			(__be32 *) &buf.data[TPM_HEADER_SIZE]);
+			(__be32 *)&buf->data[TPM_HEADER_SIZE]);
 
 out:
 	if (blob != payload->blob)
 		kfree(blob);
-	tpm_buf_destroy(&buf);
 
 	return tpm_ret_to_err(rc);
 }
@@ -453,26 +446,25 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 			   u32 blob_handle)
 {
 	struct tpm_header *head;
-	struct tpm_buf buf;
 	u16 data_len;
 	int offset;
 	u8 *data;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	rc = tpm2_start_auth_session(chip);
 	if (rc)
 		return rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
-	if (rc) {
-		tpm2_end_auth_session(chip);
-		return rc;
-	}
-
-	tpm_buf_append_name(chip, &buf, blob_handle, NULL);
+	tpm_buf_init(buf, TPM_BUFSIZE);
+	tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
+	tpm_buf_append_name(chip, buf, blob_handle, NULL);
 
 	if (!options->policyhandle) {
-		tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT,
+		tpm_buf_append_hmac_session(chip, buf, TPM2_SA_ENCRYPT,
 					    options->blobauth,
 					    options->blobauth_len);
 	} else {
@@ -481,39 +473,35 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		 * the password will end up being unencrypted on the bus, as
 		 * HMAC nonce cannot be calculated for it.
 		 */
-		tpm_buf_append_u32(&buf, 9 + options->blobauth_len);
-		tpm_buf_append_u32(&buf, options->policyhandle);
-		tpm_buf_append_u16(&buf, 0);
-		tpm_buf_append_u8(&buf, 0);
-		tpm_buf_append_u16(&buf, options->blobauth_len);
-		tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
+		tpm_buf_append_u32(buf, 9 + options->blobauth_len);
+		tpm_buf_append_u32(buf, options->policyhandle);
+		tpm_buf_append_u16(buf, 0);
+		tpm_buf_append_u8(buf, 0);
+		tpm_buf_append_u16(buf, options->blobauth_len);
+		tpm_buf_append(buf, options->blobauth, options->blobauth_len);
 		if (tpm2_chip_auth(chip)) {
-			tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, NULL, 0);
+			tpm_buf_append_hmac_session(chip, buf, TPM2_SA_ENCRYPT, NULL, 0);
 		} else  {
-			offset = buf.handles * 4 + TPM_HEADER_SIZE;
-			head = (struct tpm_header *)buf.data;
-			if (tpm_buf_length(&buf) == offset)
+			offset = buf->handles * 4 + TPM_HEADER_SIZE;
+			head = (struct tpm_header *)buf->data;
+			if (tpm_buf_length(buf) == offset)
 				head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
 		}
 	}
 
-	tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
-	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+	tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 6, "unsealing");
+	rc = tpm_buf_check_hmac_response(chip, buf, rc);
 
 	if (!rc) {
 		data_len = be16_to_cpup(
-			(__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
-		if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE) {
-			rc = -EFAULT;
-			goto out;
-		}
+			(__be16 *)&buf->data[TPM_HEADER_SIZE + 4]);
+		if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE)
+			return -EFAULT;
 
-		if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 6 + data_len) {
-			rc = -EFAULT;
-			goto out;
-		}
-		data = &buf.data[TPM_HEADER_SIZE + 6];
+		if (tpm_buf_length(buf) < TPM_HEADER_SIZE + 6 + data_len)
+			return -EFAULT;
+		data = &buf->data[TPM_HEADER_SIZE + 6];
 
 		if (payload->old_format) {
 			/* migratable flag is at the end of the key */
@@ -530,8 +518,6 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		}
 	}
 
-out:
-	tpm_buf_destroy(&buf);
 	return tpm_ret_to_err(rc);
 }
 
-- 
2.39.5


^ permalink raw reply related

* Re: [PATCH v3 01/10] tpm: Cap the number of PCR banks
From: Jarkko Sakkinen @ 2025-10-01 11:16 UTC (permalink / raw)
  To: James Bottomley
  Cc: Jonathan McDowell, linux-integrity, dpsmith, ross.philipson,
	Jarkko Sakkinen, Roberto Sassu, Peter Huewe, Jason Gunthorpe,
	David Howells, Paul Moore, James Morris, Serge E. Hallyn,
	open list, open list:KEYS/KEYRINGS, open list:SECURITY SUBSYSTEM
In-Reply-To: <cf3fb265dd70a23d598fc3d68562b4be5355e7ae.camel@HansenPartnership.com>

On Tue, Sep 30, 2025 at 10:17:22AM -0400, James Bottomley wrote:
> On Tue, 2025-09-30 at 15:36 +0300, Jarkko Sakkinen wrote:
> > On Tue, Sep 30, 2025 at 12:09:15PM +0100, Jonathan McDowell wrote:
> > > On Mon, Sep 29, 2025 at 10:48:23PM +0300, Jarkko Sakkinen wrote:
> [...]
> > > > +#define TPM2_MAX_DIGEST_SIZE	SHA512_DIGEST_SIZE
> > > > +#define TPM2_MAX_BANKS		4
> > > 
> > > Where does this max come from? It matches what I see with swtpm by 
> > > default (SHA1, SHA2-256, SHA2-384, SHA-512), so I haven't seen
> > > anything that exceeds it myself.
> > 
> > I've never seen hardware TPM that would have more than one or two
> > banks. We can double it to leave some room. This was tested with
> > swtpm defaults.
> 
> I've got a hardware TPM that comes with 3 banks by default (it's a
> chinese one which has sha1 sha256 and sm2).  swtpm isn't a good
> indicator because it's default allocation is rather pejorative (it
> disables sha1 whereas most field TPMs don't).
> 
> However, if you look at how the reference implementation works, the
> user is allowed to define any number of banks they want, up to the
> number of supported hashes.  The only limitation being there can't be
> >1 bank for the same hash.  Field TPM implementations are allowed to
> constrain this, but most don't.   The question you should be asking
> here is not how many banks does a particular implementation allow by
> default, but what's the maximum number a user could configure.

It needs some compilation time cap as the value comes from external
device. If someone hits to that value, then it needs to be increased
but as unconstrained it's a bug.


> Regards,
> 
> James
> 

BR, Jarkko

^ permalink raw reply

* [PATCH v2 1/2] landlock: Multithreading support for landlock_restrict_self()
From: Günther Noack @ 2025-10-01 11:18 UTC (permalink / raw)
  To: Mickaël Salaün
  Cc: Günther Noack, Konstantin Meskhidze, Tingmao Wang,
	Paul Moore, linux-security-module, Jann Horn
In-Reply-To: <20251001111807.18902-1-gnoack@google.com>

Introduce the LANDLOCK_RESTRICT_SELF_TSYNC flag.  With this flag, a
given Landlock ruleset is applied to all threads of the calling
process, instead of only the current one.

Without this flag, multithreaded userspace programs currently resort
to using the nptl(7)/libpsx hack for multithreaded policy enforcement,
which is also used by libcap and for setuid(2).  Using this scheme,
the threads of a process enforce the same Landlock ruleset, but the
resulting Landlock domains are still separate, which makes a
difference for Landlock's "scoped" access rights, where the domain
identity and nesting is used.  As a result, when using
LANLDOCK_SCOPE_SIGNAL, signaling between sibling threads stops
working.  This is a problem for programming languages and frameworks
which are inherently multithreaded (e.g. Go).

Cc: Mickaël Salaün <mic@digikod.net>
Cc: Paul Moore <paul@paul-moore.com>
Cc: linux-security-module@vger.kernel.org
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Günther Noack <gnoack@google.com>
---
 include/uapi/linux/landlock.h |   4 +
 security/landlock/cred.h      |  12 +
 security/landlock/limits.h    |   2 +-
 security/landlock/syscalls.c  | 433 +++++++++++++++++++++++++++++++++-
 4 files changed, 448 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
index f030adc462ee..7c6c7f004a41 100644
--- a/include/uapi/linux/landlock.h
+++ b/include/uapi/linux/landlock.h
@@ -117,11 +117,15 @@ struct landlock_ruleset_attr {
  *     future nested domains, not the one being created. It can also be used
  *     with a @ruleset_fd value of -1 to mute subdomain logs without creating a
  *     domain.
+ *
+ * %LANDLOCK_RESTRICT_SELF_TSYNC
+ *    Apply the given ruleset atomically to all threads of the current process.
  */
 /* clang-format off */
 #define LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF		(1U << 0)
 #define LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON			(1U << 1)
 #define LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF		(1U << 2)
+#define LANDLOCK_RESTRICT_SELF_TSYNC				(1U << 3)
 /* clang-format on */
 
 /**
diff --git a/security/landlock/cred.h b/security/landlock/cred.h
index c82fe63ec598..eb28eeade760 100644
--- a/security/landlock/cred.h
+++ b/security/landlock/cred.h
@@ -65,6 +65,18 @@ landlock_cred(const struct cred *cred)
 	return cred->security + landlock_blob_sizes.lbs_cred;
 }
 
+static inline void landlock_cred_copy(struct landlock_cred_security *dst,
+				      const struct landlock_cred_security *src)
+{
+	if (dst->domain)
+		landlock_put_ruleset(dst->domain);
+
+	*dst = *src;
+
+	if (dst->domain)
+		landlock_get_ruleset(src->domain);
+}
+
 static inline struct landlock_ruleset *landlock_get_current_domain(void)
 {
 	return landlock_cred(current_cred())->domain;
diff --git a/security/landlock/limits.h b/security/landlock/limits.h
index 65b5ff051674..eb584f47288d 100644
--- a/security/landlock/limits.h
+++ b/security/landlock/limits.h
@@ -31,7 +31,7 @@
 #define LANDLOCK_MASK_SCOPE		((LANDLOCK_LAST_SCOPE << 1) - 1)
 #define LANDLOCK_NUM_SCOPE		__const_hweight64(LANDLOCK_MASK_SCOPE)
 
-#define LANDLOCK_LAST_RESTRICT_SELF	LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF
+#define LANDLOCK_LAST_RESTRICT_SELF	LANDLOCK_RESTRICT_SELF_TSYNC
 #define LANDLOCK_MASK_RESTRICT_SELF	((LANDLOCK_LAST_RESTRICT_SELF << 1) - 1)
 
 /* clang-format on */
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index 0116e9f93ffe..5ba14d641c11 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -14,6 +14,7 @@
 #include <linux/capability.h>
 #include <linux/cleanup.h>
 #include <linux/compiler_types.h>
+#include <linux/completion.h>
 #include <linux/dcache.h>
 #include <linux/err.h>
 #include <linux/errno.h>
@@ -25,6 +26,7 @@
 #include <linux/security.h>
 #include <linux/stddef.h>
 #include <linux/syscalls.h>
+#include <linux/task_work.h>
 #include <linux/types.h>
 #include <linux/uaccess.h>
 #include <uapi/linux/landlock.h>
@@ -445,6 +447,416 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
 
 /* Enforcement */
 
+/*
+ * Shared state between multiple threads which are enforcing Landlock rulesets
+ * in lockstep with each other.
+ */
+struct tsync_shared_context {
+	/* The old and tentative new creds of the calling thread. */
+	const struct cred *old_cred;
+	const struct cred *new_cred;
+
+	/* An error encountered in preparation step, or 0. */
+	atomic_t preparation_error;
+
+	/*
+	 * Barrier after preparation step in the inner loop.
+	 * The calling thread waits for completion.
+	 *
+	 * Re-initialized on every round of looking for newly spawned threads.
+	 */
+	atomic_t num_preparing;
+	struct completion all_prepared;
+
+	/* Sibling threads wait for completion. */
+	struct completion ready_to_commit;
+
+	/*
+	 * Barrier after commit step (used by syscall impl to wait for
+	 * completion).
+	 */
+	atomic_t num_unfinished;
+	struct completion all_finished;
+};
+
+struct tsync_work {
+	struct callback_head work;
+	struct task_struct *task;
+	struct tsync_shared_context *shared_ctx;
+};
+
+/*
+ * restrict_one_thread - update a thread's Landlock domain in lockstep with the
+ * other threads in the same process
+ *
+ * When this is run, the same function gets run in all other threads in the same
+ * process (except for the calling thread which called landlock_restrict_self).
+ * The concurrently running invocations of restrict_one_thread coordinate
+ * through the shared ctx object to do their work in lockstep to implement
+ * all-or-nothing semantics for enforcing the new Landlock domain.
+ *
+ * Afterwards, depending on the presence of an error, all threads either commit
+ * or abort the prepared credentials.  The commit operation can not fail any more.
+ */
+static void restrict_one_thread(struct tsync_shared_context *ctx)
+{
+	int res;
+	struct cred *cred = NULL;
+	const struct cred *current_cred = current_cred();
+
+	if (current_cred == ctx->old_cred) {
+		/*
+		 * As a shortcut, switch out old_cred with new_cred, if
+		 * possible.
+		 *
+		 * Note: We are intentionally dropping the const qualifier here,
+		 * because it is required by commit_creds() and abort_creds().
+		 */
+		cred = (struct cred *)get_cred(ctx->new_cred);
+	} else {
+		/* Else, prepare new creds and populate them. */
+		cred = prepare_creds();
+
+		if (!cred) {
+			atomic_set(&ctx->preparation_error, -ENOMEM);
+
+			/*
+			 * Even on error, we need to adhere to the protocol and
+			 * coordinate with concurrently running invocations.
+			 */
+			if (atomic_dec_return(&ctx->num_preparing) == 0)
+				complete_all(&ctx->all_prepared);
+
+			goto out;
+		}
+
+		landlock_cred_copy(landlock_cred(cred),
+				   landlock_cred(ctx->new_cred));
+	}
+
+	/*
+	 * Barrier: Wait until all threads are done preparing.
+	 * After this point, we can have no more failures.
+	 */
+	if (atomic_dec_return(&ctx->num_preparing) == 0)
+		complete_all(&ctx->all_prepared);
+
+	/*
+	 * Wait for signal from calling thread that it's safe to read the
+	 * preparation error now and we are ready to commit (or abort).
+	 */
+	wait_for_completion(&ctx->ready_to_commit);
+
+	/* Abort the commit if any of the other threads had an error. */
+	res = atomic_read(&ctx->preparation_error);
+	if (res) {
+		abort_creds(cred);
+		goto out;
+	}
+
+	/* If needed, establish enforcement prerequisites. */
+	if (!ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
+		task_set_no_new_privs(current);
+
+	commit_creds(cred);
+
+out:
+	/* Notify the calling thread once all threads are done */
+	if (atomic_dec_return(&ctx->num_unfinished) == 0)
+		complete_all(&ctx->all_finished);
+}
+
+/*
+ * restrict_one_thread_callback - task_work callback for restricting a thread
+ *
+ * Calls restrict_one_thread with the struct landlock_shared_tsync_context.
+ */
+static void restrict_one_thread_callback(struct callback_head *work)
+{
+	struct tsync_work *ctx = container_of(work, struct tsync_work, work);
+
+	restrict_one_thread(ctx->shared_ctx);
+}
+
+/*
+ * struct tsync_works - a growable array of per-task contexts
+ *
+ * The zero-initialized struct represents the empty array.
+ */
+struct tsync_works {
+	struct tsync_work **works;
+	size_t size;
+	size_t capacity;
+};
+
+/*
+ * tsync_works_provide - provides a preallocated tsync_work for the given task
+ *
+ * This also stores a task pointer in the context and increments the reference
+ * count of the task.
+ *
+ * Returns:
+ *   A pointer to the preallocated context struct, with task filled in.
+ *
+ *   NULL, if we ran out of preallocated context structs.
+ */
+static struct tsync_work *tsync_works_provide(struct tsync_works *s,
+					      struct task_struct *task)
+{
+	struct tsync_work *ctx;
+
+	if (s->size >= s->capacity)
+		return NULL;
+
+	ctx = s->works[s->size];
+	s->size++;
+
+	ctx->task = get_task_struct(task);
+	return ctx;
+}
+
+/*
+ * tsync_works_grow_by - preallocates space for n more contexts in s
+ *
+ * Returns:
+ *   -ENOMEM if the (re)allocation fails
+ *   0       if the allocation succeeds, partially succeeds, or no reallocation was needed
+ */
+static int tsync_works_grow_by(struct tsync_works *s, size_t n, gfp_t flags)
+{
+	int i;
+	size_t new_capacity = s->capacity + n;
+	struct tsync_work **works;
+
+	if (new_capacity <= s->capacity)
+		return 0;
+
+	works = krealloc_array(s->works, new_capacity, sizeof(s->works[0]),
+			       flags);
+	if (IS_ERR(works))
+		return PTR_ERR(works);
+
+	s->works = works;
+
+	for (i = s->capacity; i < new_capacity; i++) {
+		s->works[i] = kzalloc(sizeof(*s->works[i]), flags);
+		if (IS_ERR(s->works[i])) {
+			/*
+			 * Leave the object in a consistent state,
+			 * but return an error.
+			 */
+			s->capacity = i;
+			return PTR_ERR(s->works[i]);
+		}
+	}
+	s->capacity = new_capacity;
+	return 0;
+}
+
+/*
+ * tsync_works_contains - checks for presence of task in s
+ */
+static bool tsync_works_contains_task(struct tsync_works *s,
+				      struct task_struct *task)
+{
+	size_t i;
+
+	for (i = 0; i < s->size; i++)
+		if (s->works[i]->task == task)
+			return true;
+	return false;
+}
+
+/*
+ * tsync_works_free - free memory held by s and drop all task references
+ */
+static void tsync_works_free(struct tsync_works *s)
+{
+	int i;
+
+	for (i = 0; i < s->size; i++)
+		put_task_struct(s->works[i]->task);
+	for (i = 0; i < s->capacity; i++)
+		kfree(s->works[i]);
+	kfree(s->works);
+	s->works = NULL;
+	s->size = 0;
+	s->capacity = 0;
+}
+
+/*
+ * restrict_sibling_threads - enables a Landlock policy for all sibling threads
+ */
+static int restrict_sibling_threads(const struct cred *old_cred,
+				    const struct cred *new_cred)
+{
+	int res;
+	struct task_struct *thread, *caller;
+	struct tsync_shared_context shared_ctx;
+	struct tsync_works works = {};
+	size_t newly_discovered_threads;
+	bool found_more_threads;
+	struct tsync_work *ctx;
+
+	atomic_set(&shared_ctx.preparation_error, 0);
+	init_completion(&shared_ctx.all_prepared);
+	init_completion(&shared_ctx.ready_to_commit);
+	atomic_set(&shared_ctx.num_unfinished, 0);
+	init_completion(&shared_ctx.all_finished);
+	shared_ctx.old_cred = old_cred;
+	shared_ctx.new_cred = new_cred;
+
+	caller = current;
+
+	/*
+	 * We schedule a pseudo-signal task_work for each of the calling task's
+	 * sibling threads.  In the task work, each thread:
+	 *
+	 * 1) runs prepare_creds() and writes back the error to
+	 *    shared_ctx.preparation_error, if needed.
+	 *
+	 * 2) signals that it's done with prepare_creds() to the calling task.
+	 *    (completion "all_prepared").
+	 *
+	 * 3) waits for the completion "ready_to_commit".  This is sent by the
+	 *    calling task after ensuring that all sibling threads have done
+	 *    with the "preparation" stage.
+	 *
+	 *    After this barrier is reached, it's safe to read
+	 *    shared_ctx.preparation_error.
+	 *
+	 * 4) reads shared_ctx.preparation_error and then either does
+	 *    commit_creds() or abort_creds().
+	 *
+	 * 5) signals that it's done altogether (barrier synchronization
+	 *    "all_finished")
+	 */
+	do {
+		found_more_threads = false;
+
+		/*
+		 * The "all_prepared" barrier is used locally to the inner loop,
+		 * this use of for_each_thread().  We can reset it on each loop
+		 * iteration because all previous loop iterations are done with
+		 * it already.
+		 *
+		 * num_preparing is initialized to 1 so that the counter can not
+		 * go to 0 and mark the completion as done before all task works
+		 * are registered.  (We decrement it at the end of this loop.)
+		 */
+		atomic_set(&shared_ctx.num_preparing, 1);
+		reinit_completion(&shared_ctx.all_prepared);
+
+		/* In RCU read-lock, count the threads we need. */
+		newly_discovered_threads = 0;
+		rcu_read_lock();
+		for_each_thread(caller, thread) {
+			/* Skip current, since it is initiating the sync. */
+			if (thread == caller)
+				continue;
+
+			/* Skip exited threads. */
+			if (thread->flags & PF_EXITING)
+				continue;
+
+			/* Skip threads that we have already seen. */
+			if (tsync_works_contains_task(&works, thread))
+				continue;
+
+			newly_discovered_threads++;
+		}
+		rcu_read_unlock();
+
+		if (newly_discovered_threads == 0)
+			break; /* done */
+
+		res = tsync_works_grow_by(&works, newly_discovered_threads,
+					  GFP_KERNEL_ACCOUNT);
+		if (res) {
+			atomic_set(&shared_ctx.preparation_error, res);
+			break;
+		}
+
+		rcu_read_lock();
+		for_each_thread(caller, thread) {
+			/* Skip current, since it is initiating the sync. */
+			if (thread == caller)
+				continue;
+
+			/* Skip exited threads. */
+			if (thread->flags & PF_EXITING)
+				continue;
+
+			/* Skip threads that we already looked at. */
+			if (tsync_works_contains_task(&works, thread))
+				continue;
+
+			/*
+			 * We found a sibling thread that is not doing its
+			 * task_work yet, and which might spawn new threads
+			 * before our task work runs, so we need at least one
+			 * more round in the outer loop.
+			 */
+			found_more_threads = true;
+
+			ctx = tsync_works_provide(&works, thread);
+			if (!ctx) {
+				/*
+				 * We ran out of preallocated contexts -- we
+				 * need to try again with this thread at a later
+				 * time!  found_more_threads is already true
+				 * at this point.
+				 */
+				break;
+			}
+
+			ctx->shared_ctx = &shared_ctx;
+
+			atomic_inc(&shared_ctx.num_preparing);
+			atomic_inc(&shared_ctx.num_unfinished);
+
+			init_task_work(&ctx->work,
+				       restrict_one_thread_callback);
+			res = task_work_add(thread, &ctx->work, TWA_SIGNAL);
+			if (res) {
+				/*
+				 * Remove the task from ctx so that we will
+				 * revisit the task at a later stage, if it
+				 * still exists.
+				 */
+				put_task_struct_rcu_user(ctx->task);
+				ctx->task = NULL;
+
+				atomic_set(&shared_ctx.preparation_error, res);
+				atomic_dec(&shared_ctx.num_preparing);
+				atomic_dec(&shared_ctx.num_unfinished);
+			}
+		}
+		rcu_read_unlock();
+
+		/*
+		 * Decrement num_preparing for current, to undo that we
+		 * initialized it to 1 at the beginning of the inner loop.
+		 */
+		if (atomic_dec_return(&shared_ctx.num_preparing) > 0)
+			wait_for_completion(&shared_ctx.all_prepared);
+	} while (found_more_threads &&
+		 !atomic_read(&shared_ctx.preparation_error));
+
+	/*
+	 * We now have all sibling threads blocking and in "prepared" state in
+	 * the task work. Ask all threads to commit.
+	 */
+	complete_all(&shared_ctx.ready_to_commit);
+
+	if (works.size)
+		wait_for_completion(&shared_ctx.all_finished);
+
+	tsync_works_free(&works);
+
+	return atomic_read(&shared_ctx.preparation_error);
+}
+
 /**
  * sys_landlock_restrict_self - Enforce a ruleset on the calling thread
  *
@@ -454,12 +866,20 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
  *         - %LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF
  *         - %LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON
  *         - %LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF
+ *         - %LANDLOCK_RESTRICT_SELF_TSYNC
  *
- * This system call enables to enforce a Landlock ruleset on the current
- * thread.  Enforcing a ruleset requires that the task has %CAP_SYS_ADMIN in its
+ * This system call enforces a Landlock ruleset on the current thread.
+ * Enforcing a ruleset requires that the task has %CAP_SYS_ADMIN in its
  * namespace or is running with no_new_privs.  This avoids scenarios where
  * unprivileged tasks can affect the behavior of privileged children.
  *
+ * If %LANDLOCK_RESTRICT_SELF_TSYNC is specified in @flags, all other threads of
+ * the process will be brought into the exact same Landlock configuration as the
+ * calling thread.  This includes both the enforced ruleset and logging
+ * configuration, and happens irrespective of previously established rulesets
+ * and logging configurations on these threads.  If required, this operation
+ * also enables the no_new_privs flag for these threads.
+ *
  * Possible returned errors are:
  *
  * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
@@ -484,6 +904,7 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 	struct landlock_cred_security *new_llcred;
 	bool __maybe_unused log_same_exec, log_new_exec, log_subdomains,
 		prev_log_subdomains;
+	int res;
 
 	if (!is_initialized())
 		return -EOPNOTSUPP;
@@ -566,5 +987,13 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 	new_llcred->domain_exec |= BIT(new_dom->num_layers - 1);
 #endif /* CONFIG_AUDIT */
 
+	if (flags & LANDLOCK_RESTRICT_SELF_TSYNC) {
+		res = restrict_sibling_threads(current_cred(), new_cred);
+		if (res != 0) {
+			abort_creds(new_cred);
+			return res;
+		}
+	}
+
 	return commit_creds(new_cred);
 }
-- 
2.51.0.618.g983fd99d29-goog


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