[PATCH v2] KEYS: trusted: Debugging as a feature

Jarkko Sakkinen
2026-03-24T11:00:30Z

TPM_DEBUG, and other similar flags, are a non-standard way to specify a
feature in Linux kernel. Introduce CONFIG_TRUSTED_KEYS_DEBUG for
trusted keys, and use it to replace these ad-hoc feature flags.

Given that trusted keys debug dumps can contain sensitive data, harden
the feature as follows:

1. In the Kconfig description postulate that pr_debug() statements must be
used.
2. Use pr_debug() statements in TPM 1.x driver to print the protocol dump.

Traces, when actually needed, can be easily enabled by providing
trusted.dyndbg='+p' in the kernel command-line.

Cc: Srish Srinivasan <ssrish@linux.ibm.com>
Reported-by: Nayna Jain <nayna@linux.ibm.com>
Closes: https://lore.kernel.org/all/7f8b8478-5cd8-4d97-bfd0-341fd5cf10f9@linux.ibm.com/
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
v2:
- Implement for all trusted keys backends.
- Add HAVE_TRUSTED_KEYS_DEBUG as it is a good practice despite full
coverage.
---
include/keys/trusted-type.h | 18 +++++-------
security/keys/trusted-keys/Kconfig | 19 ++++++++++++
security/keys/trusted-keys/trusted_caam.c | 4 +--
security/keys/trusted-keys/trusted_tpm1.c | 36 +++++++++++------------
4 files changed, 46 insertions(+), 31 deletions(-)

diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
index 03527162613f..620a1f890b6b 100644
--- a/include/keys/trusted-type.h
+++ b/include/keys/trusted-type.h
@@ -83,18 +83,16 @@ struct trusted_key_source {

extern struct key_type key_type_trusted;

-#define TRUSTED_DEBUG 0
-
-#if TRUSTED_DEBUG
+#ifdef CONFIG_TRUSTED_KEYS_DEBUG
static inline void dump_payload(struct trusted_key_payload *p)
{
- pr_info("key_len %d\n", p->key_len);
- print_hex_dump(KERN_INFO, "key ", DUMP_PREFIX_NONE,
- 16, 1, p->key, p->key_len, 0);
- pr_info("bloblen %d\n", p->blob_len);
- print_hex_dump(KERN_INFO, "blob ", DUMP_PREFIX_NONE,
- 16, 1, p->blob, p->blob_len, 0);
- pr_info("migratable %d\n", p->migratable);
+ pr_debug("key_len %d\n", p->key_len);
+ print_hex_dump_debug("key ", DUMP_PREFIX_NONE,
+ 16, 1, p->key, p->key_len, 0);
+ pr_debug("bloblen %d\n", p->blob_len);
+ print_hex_dump_debug("blob ", DUMP_PREFIX_NONE,
+ 16, 1, p->blob, p->blob_len, 0);
+ pr_debug("migratable %d\n", p->migratable);
}
#else
static inline void dump_payload(struct trusted_key_payload *p)
diff --git a/security/keys/trusted-keys/Kconfig b/security/keys/trusted-keys/Kconfig
index 9e00482d886a..2ad9ba0e03f1 100644
--- a/security/keys/trusted-keys/Kconfig
+++ b/security/keys/trusted-keys/Kconfig
@@ -1,10 +1,25 @@
config HAVE_TRUSTED_KEYS
bool

+config HAVE_TRUSTED_KEYS_DEBUG
+ bool
+
+config TRUSTED_KEYS_DEBUG
+ bool "Debug trusted keys"
+ depends on HAVE_TRUSTED_KEYS_DEBUG
+ default n
+ help
+ Trusted keys backends and core code that support debug dumps
+ can opt-in that feature here. Dumps must only use DEBUG
+ level output, as sensitive data may pass by. In the
+ kernel-command line traces can be enabled via
+ trusted.dyndbg='+p'.
+
config TRUSTED_KEYS_TPM
bool "TPM-based trusted keys"
depends on TCG_TPM >= TRUSTED_KEYS
default y
+ select HAVE_TRUSTED_KEYS_DEBUG
select CRYPTO_HASH_INFO
select CRYPTO_LIB_SHA1
select CRYPTO_LIB_UTILS
@@ -23,6 +38,7 @@ config TRUSTED_KEYS_TEE
bool "TEE-based trusted keys"
depends on TEE >= TRUSTED_KEYS
default y
+ select HAVE_TRUSTED_KEYS_DEBUG
select HAVE_TRUSTED_KEYS
help
Enable use of the Trusted Execution Environment (TEE) as trusted
@@ -33,6 +49,7 @@ config TRUSTED_KEYS_CAAM
depends on CRYPTO_DEV_FSL_CAAM_JR >= TRUSTED_KEYS
select CRYPTO_DEV_FSL_CAAM_BLOB_GEN
default y
+ select HAVE_TRUSTED_KEYS_DEBUG
select HAVE_TRUSTED_KEYS
help
Enable use of NXP's Cryptographic Accelerator and Assurance Module
@@ -42,6 +59,7 @@ config TRUSTED_KEYS_DCP
bool "DCP-based trusted keys"
depends on CRYPTO_DEV_MXS_DCP >= TRUSTED_KEYS
default y
+ select HAVE_TRUSTED_KEYS_DEBUG
select HAVE_TRUSTED_KEYS
help
Enable use of NXP's DCP (Data Co-Processor) as trusted key backend.
@@ -50,6 +68,7 @@ config TRUSTED_KEYS_PKWM
bool "PKWM-based trusted keys"
depends on PSERIES_PLPKS >= TRUSTED_KEYS
default y
+ select HAVE_TRUSTED_KEYS_DEBUG
select HAVE_TRUSTED_KEYS
help
Enable use of IBM PowerVM Key Wrapping Module (PKWM) as a trusted key backend.
diff --git a/security/keys/trusted-keys/trusted_caam.c b/security/keys/trusted-keys/trusted_caam.c
index 601943ce0d60..015cddc6b53c 100644
--- a/security/keys/trusted-keys/trusted_caam.c
+++ b/security/keys/trusted-keys/trusted_caam.c
@@ -28,10 +28,10 @@ static const match_table_t key_tokens = {
{opt_err, NULL}
};

-#ifdef CAAM_DEBUG
+#ifdef CONFIG_TRUSTED_KEYS_DEBUG
static inline void dump_options(const struct caam_pkey_info *pkey_info)
{
- pr_info("key encryption algo %d\n", pkey_info->key_enc_algo);
+ pr_debug("key encryption algo %d\n", pkey_info->key_enc_algo);
}
#else
static inline void dump_options(const struct caam_pkey_info *pkey_info)
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index c865c97aa1b4..8fe889c7cdd1 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -46,38 +46,36 @@ enum {
SRK_keytype = 4
};

-#define TPM_DEBUG 0
-
-#if TPM_DEBUG
+#ifdef CONFIG_TRUSTED_KEYS_DEBUG
static inline void dump_options(struct trusted_key_options *o)
{
- pr_info("sealing key type %d\n", o->keytype);
- pr_info("sealing key handle %0X\n", o->keyhandle);
- pr_info("pcrlock %d\n", o->pcrlock);
- pr_info("pcrinfo %d\n", o->pcrinfo_len);
- print_hex_dump(KERN_INFO, "pcrinfo ", DUMP_PREFIX_NONE,
- 16, 1, o->pcrinfo, o->pcrinfo_len, 0);
+ pr_debug("sealing key type %d\n", o->keytype);
+ pr_debug("sealing key handle %0X\n", o->keyhandle);
+ pr_debug("pcrlock %d\n", o->pcrlock);
+ pr_debug("pcrinfo %d\n", o->pcrinfo_len);
+ print_hex_dump_debug("pcrinfo ", DUMP_PREFIX_NONE,
+ 16, 1, o->pcrinfo, o->pcrinfo_len, 0);
}

static inline void dump_sess(struct osapsess *s)
{
- print_hex_dump(KERN_INFO, "trusted-key: handle ", DUMP_PREFIX_NONE,
- 16, 1, &s->handle, 4, 0);
- pr_info("secret:\n");
- print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE,
- 16, 1, &s->secret, SHA1_DIGEST_SIZE, 0);
- pr_info("trusted-key: enonce:\n");
- print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE,
- 16, 1, &s->enonce, SHA1_DIGEST_SIZE, 0);
+ print_hex_dump_debug("trusted-key: handle ", DUMP_PREFIX_NONE,
+ 16, 1, &s->handle, 4, 0);
+ pr_debug("secret:\n");
+ print_hex_dump_debug("", DUMP_PREFIX_NONE,
+ 16, 1, &s->secret, SHA1_DIGEST_SIZE, 0);
+ pr_debug("trusted-key: enonce:\n");
+ print_hex_dump_debug("", DUMP_PREFIX_NONE,
+ 16, 1, &s->enonce, SHA1_DIGEST_SIZE, 0);
}

static inline void dump_tpm_buf(unsigned char *buf)
{
int len;

- pr_info("\ntpm buffer\n");
+ pr_debug("\ntpm buffer\n");
len = LOAD32(buf, TPM_SIZE_OFFSET);
- print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE, 16, 1, buf, len, 0);
+ print_hex_dump_debug("", DUMP_PREFIX_NONE, 16, 1, buf, len, 0);
}
#else
static inline void dump_options(struct trusted_key_options *o)
--
2.47.3