* [v6 00/10] Reintroduce Hornet LSM
From: Blaise Boscaccy @ 2026-04-29 19:14 UTC (permalink / raw)
To: Blaise Boscaccy, Jonathan Corbet, Paul Moore, James Morris,
Serge E. Hallyn, Mickaël Salaün, Günther Noack,
Dr. David Alan Gilbert, Andrew Morton, James.Bottomley, dhowells,
Fan Wu, Ryan Foster, Randy Dunlap, linux-security-module,
linux-doc, linux-kernel, bpf, Song Liu
This patch series introduces the next iteration of the Hornet LSM.
Hornet’s goal is to provide a secure and extensible in-kernel
signature verification mechanism for eBPF programs.
Hornet addresses concerns from users who require strict audit trails and
verification guarantees for eBPF programs, especially in
security-sensitive environments. Many production systems need assurance
that only authorized, unmodified eBPF programs are loaded into the
kernel. Hornet provides this assurance through cryptographic signature
verification.
The currently accepted loader-plus-map signature verification scheme,
mandated by Alexei and KP, is simple to implement and generally
acceptable if users and administrators are satisfied with it. However,
verifying both the loader and the maps offers additional benefits
beyond verifying the loader alone:
1. Security and Audit Integrity
A key advantage is that the LSM hook for authorizing BPF program loads
can operate after signature verification. This ensures:
* Access control decisions are based on verified signature status.
* Accurate system state measurement and logging.
* Log entries claiming a verified signature are truthful, avoiding
misleading records where only the loader was verified while the actual
BPF program verification occurs later without logging.
2. TOCTOU Attack Prevention
The current map hash implementation may be vulnerable to a TOCTOU
attack because it allows unfrozen maps to cache a previously
calculated hash. The accepted “trusted loader” scheme cannot detect
this and may permit loading altered maps.
3. Supply Chain Integrity
Verify that eBPF programs and their associated map data have not been
modified since they were built and signed, in the kernel proper, may
aid in protecting against supply chain attacks.
This approach addresses concerns from users who require strict audit
trails and verification guarantees, especially in security-sensitive
environments. Map hashes for extended verification are passed via the
existing PKCS#7 UAPI and verified by the crypto subsystem. Hornet then
calculates the program’s verification state. Hornet itself does not
enforce a policy on whether unsigned or partially signed programs
should be rejected. It delegates that decision to downstream LSMs
hook, making it a composable building block in a larger security
architecture.
Changes in V6:
- Doc cleanup
- Error handling improvements
- Support for shareable maps
Link to V5: https://lore.kernel.org/linux-security-module/20260420212653.438685-1-bboscaccy@linux.microsoft.com/
Changes in V5:
- Added IPE documentation
Link to V4: https://lore.kernel.org/linux-security-module/20260416173500.176716-1-bboscaccy@linux.microsoft.com/
Changes in V4:
- IPE integration
- Arbitrary keyring support
Link to V3: https://lore.kernel.org/linux-security-module/20260326060655.2550595-1-bboscaccy@linux.microsoft.com/
Changes in V3:
- Updated for signed attribute patch series changes
- Added some new result enum values
- Minor documentation clarification
- Misc style fixes
- Added missing signed-off-by tags
Link to V2: https://lore.kernel.org/linux-security-module/20260227233930.2418522-1-bboscaccy@linux.microsoft.com/
Changes in V2:
- Addressed possible TocTou races in hash verification
- Improved documentation and tooling
- Added Alexie's nack
Link to RFC: https://lore.kernel.org/linux-security-module/20251211021257.1208712-1-bboscaccy@linux.microsoft.com/
Blaise Boscaccy (6):
lsm: security: Add additional enum values for bpf integrity checks
security: Hornet LSM
hornet: Introduce gen_sig
hornet: Add a light skeleton data extractor scripts
selftests/hornet: Add a selftest for the Hornet LSM
ipe: Add BPF program load policy enforcement via Hornet integration
James Bottomley (3):
crypto: pkcs7: add flag for validated trust on a signed info block
crypto: pkcs7: add ability to extract signed attributes by OID
crypto: pkcs7: add tests for pkcs7_get_authattr
Paul Moore (1):
lsm: framework for BPF integrity verification
Documentation/admin-guide/LSM/Hornet.rst | 323 +++++++++++++++
Documentation/admin-guide/LSM/index.rst | 1 +
Documentation/admin-guide/LSM/ipe.rst | 162 +++++++-
Documentation/security/ipe.rst | 39 ++
MAINTAINERS | 9 +
certs/system_keyring.c | 1 +
crypto/asymmetric_keys/Makefile | 4 +-
crypto/asymmetric_keys/pkcs7_aa.asn1 | 18 +
crypto/asymmetric_keys/pkcs7_key_type.c | 44 +-
crypto/asymmetric_keys/pkcs7_parser.c | 81 ++++
crypto/asymmetric_keys/pkcs7_parser.h | 1 +
crypto/asymmetric_keys/pkcs7_trust.c | 1 +
include/crypto/pkcs7.h | 4 +
include/linux/lsm_hook_defs.h | 5 +
include/linux/oid_registry.h | 3 +
include/linux/security.h | 28 ++
include/uapi/linux/lsm.h | 1 +
scripts/Makefile | 1 +
scripts/hornet/Makefile | 5 +
scripts/hornet/extract-insn.sh | 27 ++
scripts/hornet/extract-map.sh | 27 ++
scripts/hornet/extract-skel.sh | 27 ++
scripts/hornet/gen_sig.c | 397 +++++++++++++++++++
scripts/hornet/write-sig.sh | 27 ++
security/Kconfig | 3 +-
security/Makefile | 1 +
security/hornet/Kconfig | 13 +
security/hornet/Makefile | 7 +
security/hornet/hornet.asn1 | 12 +
security/hornet/hornet_lsm.c | 350 ++++++++++++++++
security/ipe/Kconfig | 14 +
security/ipe/audit.c | 15 +
security/ipe/eval.c | 73 +++-
security/ipe/eval.h | 11 +
security/ipe/hooks.c | 63 +++
security/ipe/hooks.h | 15 +
security/ipe/ipe.c | 14 +
security/ipe/ipe.h | 3 +
security/ipe/policy.h | 14 +
security/ipe/policy_parser.c | 27 ++
security/security.c | 75 +++-
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/hornet/Makefile | 63 +++
tools/testing/selftests/hornet/loader.c | 21 +
tools/testing/selftests/hornet/trivial.bpf.c | 33 ++
45 files changed, 2056 insertions(+), 8 deletions(-)
create mode 100644 Documentation/admin-guide/LSM/Hornet.rst
create mode 100644 crypto/asymmetric_keys/pkcs7_aa.asn1
create mode 100644 scripts/hornet/Makefile
create mode 100755 scripts/hornet/extract-insn.sh
create mode 100755 scripts/hornet/extract-map.sh
create mode 100755 scripts/hornet/extract-skel.sh
create mode 100644 scripts/hornet/gen_sig.c
create mode 100755 scripts/hornet/write-sig.sh
create mode 100644 security/hornet/Kconfig
create mode 100644 security/hornet/Makefile
create mode 100644 security/hornet/hornet.asn1
create mode 100644 security/hornet/hornet_lsm.c
create mode 100644 tools/testing/selftests/hornet/Makefile
create mode 100644 tools/testing/selftests/hornet/loader.c
create mode 100644 tools/testing/selftests/hornet/trivial.bpf.c
--
2.53.0
^ permalink raw reply
* Re: [PATCH v5 10/10] ipe: Add BPF program load policy enforcement via Hornet integration
From: Blaise Boscaccy @ 2026-04-29 18:35 UTC (permalink / raw)
To: Fan Wu
Cc: Jonathan Corbet, Paul Moore, James Morris, Serge E. Hallyn,
Mickaël Salaün, Günther Noack,
Dr. David Alan Gilbert, Andrew Morton, James.Bottomley, dhowells,
Fan Wu, Ryan Foster, Randy Dunlap, linux-security-module,
linux-doc, linux-kernel, bpf, Song Liu
In-Reply-To: <CAKtyLkEEjzcjptcN8DU70HfDJ7bw18S2mtgFPUyn9P46QUhsmQ@mail.gmail.com>
Fan Wu <wufan@kernel.org> writes:
> On Mon, Apr 20, 2026 at 2:27 PM Blaise Boscaccy
> <bboscaccy@linux.microsoft.com> wrote:
>>
>> Add support for the bpf_prog_load_post_integrity LSM hook, enabling IPE
>> to make policy decisions about BPF program loading based on integrity
>> verdicts provided by the Hornet LSM.
>>
>> New policy operation:
>> op=BPF_PROG_LOAD - Matches BPF program load events
>>
>> New policy properties:
>> bpf_signature=NONE - No Verdict
>> bpf_signature=OK - Program signature and map hashes verified
>> bpf_signature=UNSIGNED - No signature provided
>> bpf_signature=PARTIALSIG - Signature OK but no map hash data
>> bpf_signature=UNKNOWNKEY - Cert not trusted
>> bpf_signature=UNEXPECTED - An unexpected hash value was encountered
>> bpf_signature=FAULT - System error during verification
>> bpf_signature=BADSIG - Signature or map hash verification failed
>> bpf_keyring=BUILTIN - Program was signed using a builtin keyring
>> bpf_keyring=SECONDARY - Program was signed using the secondary keyring
>> bpf_keyring=PLATFORM - Program was signed using the platform keyring
>> bpf_kernel=TRUE - Program originated from kernelspace
>> bpf_kernel=FALSE - Program originated from userspace
>>
>> These properties map directly to the lsm_integrity_verdict enum values
>> provided by the Hornet LSM through security_bpf_prog_load_post_integrity.
>>
>> The feature is gated on CONFIG_IPE_PROP_BPF_SIGNATURE which depends on
>> CONFIG_SECURITY_HORNET.
>>
>> Signed-off-by: Blaise Boscaccy <bboscaccy@linux.microsoft.com>
>> ---
>
> ...
>
>> diff --git a/security/ipe/hooks.c b/security/ipe/hooks.c
>> index 0ae54a880405a..03541e5bb7f60 100644
>> --- a/security/ipe/hooks.c
>> +++ b/security/ipe/hooks.c
>> @@ -340,3 +340,40 @@ int ipe_inode_setintegrity(const struct inode *inode,
>> return -EINVAL;
>> }
>> #endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
>> +
>> +#ifdef CONFIG_IPE_PROP_BPF_SIGNATURE
>> +/**
>> + * ipe_bpf_prog_load_post_integrity() - ipe security hook for BPF program load.
>> + * @prog: Supplies the BPF program being loaded.
>> + * @attr: Supplies the bpf syscall attributes.
>> + * @token: Supplies the BPF token, if any.
>> + * @kernel: Whether the call originated from the kernel.
>> + * @lsmid: Supplies the LSM ID of the integrity provider.
>> + * @verdict: Supplies the integrity verdict from the provider (e.g. Hornet).
>> + *
>> + * This LSM hook is called after an integrity verification LSM (such as Hornet)
>> + * has evaluated a BPF program's cryptographic signature. IPE uses the verdict
>> + * to make a policy-based allow/deny decision.
>> + *
>> + * Return:
>> + * * %0 - Success
>> + * * %-EACCES - Did not pass IPE policy
>> + */
>> +int ipe_bpf_prog_load_post_integrity(struct bpf_prog *prog,
>> + union bpf_attr *attr,
>> + struct bpf_token *token,
>> + bool kernel,
>> + const struct lsm_id *lsmid,
>> + enum lsm_integrity_verdict verdict)
>> +{
>> + struct ipe_eval_ctx ctx = IPE_EVAL_CTX_INIT;
>> +
>> + ctx.op = IPE_OP_BPF_PROG_LOAD;
>> + ctx.hook = IPE_HOOK_BPF_PROG_LOAD;
>> + ctx.bpf_verdict = verdict;
>> + ctx.bpf_keyring_id = attr->keyring_id;
>> + ctx.bpf_kernel = kernel;
>> +
>> + return ipe_evaluate_event(&ctx);
>> +}
>> +#endif /* CONFIG_IPE_PROP_BPF_SIGNATURE */
>> diff --git a/security/ipe/hooks.h b/security/ipe/hooks.h
>> index 07db373327402..95b74f7899750 100644
>> --- a/security/ipe/hooks.h
>> +++ b/security/ipe/hooks.h
>> @@ -10,6 +10,7 @@
>> #include <linux/security.h>
>> #include <linux/blk_types.h>
>> #include <linux/fsverity.h>
>> +#include <linux/bpf.h>
>>
>> enum ipe_hook_type {
>> IPE_HOOK_BPRM_CHECK = 0,
>> @@ -18,6 +19,7 @@ enum ipe_hook_type {
>> IPE_HOOK_MPROTECT,
>> IPE_HOOK_KERNEL_READ,
>> IPE_HOOK_KERNEL_LOAD,
>> + IPE_HOOK_BPF_PROG_LOAD,
>> __IPE_HOOK_MAX
>> };
>>
>> @@ -52,4 +54,13 @@ int ipe_inode_setintegrity(const struct inode *inode, enum lsm_integrity_type ty
>> const void *value, size_t size);
>> #endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
>>
>> +#ifdef CONFIG_IPE_PROP_BPF_SIGNATURE
>> +int ipe_bpf_prog_load_post_integrity(struct bpf_prog *prog,
>> + union bpf_attr *attr,
>> + struct bpf_token *token,
>> + bool kernel,
>> + const struct lsm_id *lsmid,
>> + enum lsm_integrity_verdict verdict);
>> +#endif /* CONFIG_IPE_PROP_BPF_SIGNATURE */
>> +
>> #endif /* _IPE_HOOKS_H */
>> diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c
>> index 495bb765de1b8..6502d4ddc641c 100644
>> --- a/security/ipe/ipe.c
>> +++ b/security/ipe/ipe.c
>> @@ -60,6 +60,9 @@ static struct security_hook_list ipe_hooks[] __ro_after_init = {
>> #ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
>> LSM_HOOK_INIT(inode_setintegrity, ipe_inode_setintegrity),
>> #endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
>> +#ifdef CONFIG_IPE_PROP_BPF_SIGNATURE
>> + LSM_HOOK_INIT(bpf_prog_load_post_integrity, ipe_bpf_prog_load_post_integrity),
>> +#endif /* CONFIG_IPE_PROP_BPF_SIGNATURE */
>> };
>>
>
> IPE only registers bpf_prog_load_post_integrity(), which fires only
> when Hornet calls security_bpf_prog_load_post_integrity. If Hornet
> isn't enabled via lsm=, this hook never triggers, and an IPE policy
> like "DEFAULT op=BPF_PROG_LOAD action=DENY" silently allows every
> load.
>
> I think IPE should register bpf_prog_load() as well, post_integrity()
> should only store the verdict to a per-prog blob, and bpf_prog_load
> reads it and evaluates policy.
>
Sounds reasonable to me.
> -Fan
^ permalink raw reply
* Re: [PATCH v5 06/10] security: Hornet LSM
From: Blaise Boscaccy @ 2026-04-29 18:34 UTC (permalink / raw)
To: Fan Wu
Cc: Jonathan Corbet, Paul Moore, James Morris, Serge E. Hallyn,
Mickaël Salaün, Günther Noack,
Dr. David Alan Gilbert, Andrew Morton, James.Bottomley, dhowells,
Fan Wu, Ryan Foster, Randy Dunlap, linux-security-module,
linux-doc, linux-kernel, bpf, Song Liu
In-Reply-To: <CAKtyLkF5L_sDHmtT2eVhmHLdhB_rAxWzotUJER6A5DFQ=S6EPw@mail.gmail.com>
Fan Wu <wufan@kernel.org> writes:
> On Mon, Apr 20, 2026 at 2:27 PM Blaise Boscaccy
> <bboscaccy@linux.microsoft.com> wrote:
>>
>> This adds the Hornet Linux Security Module which provides enhanced
>> signature verification and data validation for eBPF programs. This
>> allows users to continue to maintain an invariant that all code
>> running inside of the kernel has actually been signed and verified, by
>> the kernel.
>>
>> This effort builds upon the currently excepted upstream solution. It
>> further hardens it by providing deterministic, in-kernel checking of
>> map hashes to solidify auditing along with preventing TOCTOU attacks
>> against lskel map hashes.
>>
>> Target map hashes are passed in via PKCS#7 signed attributes. Hornet
>> determines the extent which the eBFP program is signed and defers to
>> other LSMs for policy decisions.
>>
>> Signed-off-by: Blaise Boscaccy <bboscaccy@linux.microsoft.com>
>> Nacked-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
>
> ...
>
>> diff --git a/security/hornet/Kconfig b/security/hornet/Kconfig
>> new file mode 100644
>> index 0000000000000..19406aa237ac6
>> --- /dev/null
>> +++ b/security/hornet/Kconfig
>> @@ -0,0 +1,11 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +config SECURITY_HORNET
>> + bool "Hornet support"
>> + depends on SECURITY
>
> The dependency doesn't seem to be complete, for example,
> PKCS7_MESSAGE_PARSER is not selected.
>
>> + default n
>> + help
>> + This selects Hornet.
>> + Further information can be found in
>> + Documentation/admin-guide/LSM/Hornet.rst.
>> +
>> + If you are unsure how to answer this question, answer N.
>> diff --git a/security/hornet/Makefile b/security/hornet/Makefile
>> new file mode 100644
>> index 0000000000000..26b6f954f762e
>> --- /dev/null
>> +++ b/security/hornet/Makefile
>> @@ -0,0 +1,7 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +obj-$(CONFIG_SECURITY_HORNET) := hornet.o
>> +
>> +hornet-y := hornet.asn1.o \
>> + hornet_lsm.o \
>> +
>> +$(obj)/hornet.asn1.o: $(obj)/hornet.asn1.c $(obj)/hornet.asn1.h
>> diff --git a/security/hornet/hornet.asn1 b/security/hornet/hornet.asn1
>> new file mode 100644
>> index 0000000000000..c8d47b16b65d7
>> --- /dev/null
>> +++ b/security/hornet/hornet.asn1
>> @@ -0,0 +1,13 @@
>> +-- SPDX-License-Identifier: BSD-3-Clause
>> +--
>> +-- Copyright (C) 2009 IETF Trust and the persons identified as authors
>> +-- of the code
>
> I'm not a lawyer, but since this is a new AA which is not in the RFC,
> should the copyright belong to IETF?
>
gah thanks.
>> +--
>> +-- https://www.rfc-editor.org/rfc/rfc5652#section-3
>> +
>> +HornetData ::= SET OF Map
>> +
>> +Map ::= SEQUENCE {
>> + index INTEGER ({ hornet_map_index }),
>> + sha OCTET STRING ({ hornet_map_hash })
>> +} ({ hornet_next_map })
>> diff --git a/security/hornet/hornet_lsm.c b/security/hornet/hornet_lsm.c
>> new file mode 100644
>> index 0000000000000..f7d62fe6229c9
>> --- /dev/null
>> +++ b/security/hornet/hornet_lsm.c
>> @@ -0,0 +1,346 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Hornet Linux Security Module
>> + *
>> + * Author: Blaise Boscaccy <bboscaccy@linux.microsoft.com>
>> + *
>> + * Copyright (C) 2026 Microsoft Corporation
>> + */
>> +
>> +#include <linux/lsm_hooks.h>
>> +#include <uapi/linux/lsm.h>
>> +#include <linux/bpf.h>
>> +#include <linux/verification.h>
>> +#include <crypto/public_key.h>
>> +#include <linux/module_signature.h>
>> +#include <crypto/pkcs7.h>
>> +#include <linux/sort.h>
>> +#include <linux/asn1_decoder.h>
>> +#include <linux/oid_registry.h>
>> +#include "hornet.asn1.h"
>> +
>> +#define MAX_USED_MAPS 64
>> +
>> +struct hornet_maps {
>> + bpfptr_t fd_array;
>> +};
>> +
>> +/* The only hashing algorithm available is SHA256 due to it be hardcoded
>> + in the bpf subsystem. */
>> +
>> +struct hornet_parse_context {
>> + int indexes[MAX_USED_MAPS];
>> + bool skips[MAX_USED_MAPS];
>> + unsigned char hashes[SHA256_DIGEST_SIZE * MAX_USED_MAPS];
>> + int hash_count;
>> +};
>> +
>> +struct hornet_prog_security_struct {
>> + bool checked[MAX_USED_MAPS];
>> + unsigned char hashes[SHA256_DIGEST_SIZE * MAX_USED_MAPS];
>> +};
>> +
>> +struct hornet_map_security_struct {
>> + bool checked;
>> + int index;
>> +};
>> +
>
> Can maps be shared between programs? If so, since the LSM blob is
> per-map, a second program's load will overwrite map_security->index
> set by the first. A later run of the first program would then fail to
> find its own map.
>
Yes, it can. We can support that.
>> +struct lsm_blob_sizes hornet_blob_sizes __ro_after_init = {
>> + .lbs_bpf_map = sizeof(struct hornet_map_security_struct),
>> + .lbs_bpf_prog = sizeof(struct hornet_prog_security_struct),
>> +};
>> +
>> +static inline struct hornet_prog_security_struct *
>> +hornet_bpf_prog_security(struct bpf_prog *prog)
>> +{
>> + return prog->aux->security + hornet_blob_sizes.lbs_bpf_prog;
>> +}
>> +
>> +static inline struct hornet_map_security_struct *
>> +hornet_bpf_map_security(struct bpf_map *map)
>> +{
>> + return map->security + hornet_blob_sizes.lbs_bpf_map;
>> +}
>> +
>> +static int hornet_verify_hashes(struct hornet_maps *maps,
>> + struct hornet_parse_context *ctx,
>> + struct bpf_prog *prog)
>> +{
>> + int map_fd;
>> + u32 i;
>> + struct bpf_map *map;
>> + int err = 0;
>> + unsigned char hash[SHA256_DIGEST_SIZE];
>> + struct hornet_prog_security_struct *security = hornet_bpf_prog_security(prog);
>> + struct hornet_map_security_struct *map_security;
>> +
>> + for (i = 0; i < ctx->hash_count; i++) {
>> + if (ctx->skips[i])
>> + continue;
>> +
>> + err = copy_from_bpfptr_offset(&map_fd, maps->fd_array,
>> + ctx->indexes[i] * sizeof(map_fd),
>> + sizeof(map_fd));
>> + if (err < 0)
>> + return LSM_INT_VERDICT_FAULT;
>> +
>> + CLASS(fd, f)(map_fd);
>> + if (fd_empty(f))
>> + return LSM_INT_VERDICT_FAULT;
>> + if (unlikely(fd_file(f)->f_op != &bpf_map_fops))
>> + return LSM_INT_VERDICT_FAULT;
>> +
>> + map = fd_file(f)->private_data;
>> + if (!map->frozen)
>> + return LSM_INT_VERDICT_FAULT;
>> +
>> + map->ops->map_get_hash(map, SHA256_DIGEST_SIZE, hash);
>> +
>> + err = memcmp(hash, &ctx->hashes[i * SHA256_DIGEST_SIZE],
>> + SHA256_DIGEST_SIZE);
>> + if (err)
>> + return LSM_INT_VERDICT_UNEXPECTED;
>> +
>> + security->checked[i] = true;
>> + memcpy(&security->hashes[i * SHA256_DIGEST_SIZE], hash, SHA256_DIGEST_SIZE);
>> + map_security = hornet_bpf_map_security(map);
>> + map_security->checked = true;
>> + map_security->index = i;
>> + }
>> + return LSM_INT_VERDICT_OK;
>> +}
>> +
>> +int hornet_next_map(void *context, size_t hdrlen,
>> + unsigned char tag,
>> + const void *value, size_t vlen)
>> +{
>> + struct hornet_parse_context *ctx = (struct hornet_parse_context *)context;
>> +
>> + if (++ctx->hash_count >= MAX_USED_MAPS)
>> + return -EINVAL;
>> + return 0;
>> +}
>> +
>> +int hornet_map_index(void *context, size_t hdrlen,
>> + unsigned char tag,
>> + const void *value, size_t vlen)
>> +{
>> + struct hornet_parse_context *ctx = (struct hornet_parse_context *)context;
>> +
>> + if (vlen > 1)
>> + return -EINVAL;
>> +
>> + ctx->indexes[ctx->hash_count] = *(u8 *)value;
>> + return 0;
>> +}
>> +
>> +int hornet_map_hash(void *context, size_t hdrlen,
>> + unsigned char tag,
>> + const void *value, size_t vlen)
>> +
>> +{
>> + struct hornet_parse_context *ctx = (struct hornet_parse_context *)context;
>> +
>> + if (vlen != SHA256_DIGEST_SIZE && vlen != 0)
>> + return -EINVAL;
>> +
>> + if (vlen) {
>> + ctx->skips[ctx->hash_count] = false;
>> + memcpy(&ctx->hashes[ctx->hash_count * SHA256_DIGEST_SIZE], value, vlen);
>> + } else
>> + ctx->skips[ctx->hash_count] = true;
>> +
>> + return 0;
>> +}
>> +
>> +static int hornet_check_program(struct bpf_prog *prog, union bpf_attr *attr,
>> + struct bpf_token *token, bool is_kernel,
>> + enum lsm_integrity_verdict *verdict)
>> +{
>> + struct hornet_maps maps = {0};
>> + bpfptr_t usig = make_bpfptr(attr->signature, is_kernel);
>> + struct pkcs7_message *msg;
>> + struct hornet_parse_context *ctx;
>> + void *sig;
>> + int err;
>> + const void *authattrs;
>> + size_t authattrs_len;
>> + struct key *key;
>> +
>> + if (!attr->signature) {
>> + *verdict = LSM_INT_VERDICT_UNSIGNED;
>> + return 0;
>> + }
>> +
>> + ctx = kzalloc(sizeof(struct hornet_parse_context), GFP_KERNEL);
>> + if (!ctx)
>> + return -ENOMEM;
>> +
>> + maps.fd_array = make_bpfptr(attr->fd_array, is_kernel);
>> + sig = kzalloc(attr->signature_size, GFP_KERNEL);
>> + if (!sig) {
>> + err = -ENOMEM;
>> + goto out;
>> + }
>> + err = copy_from_bpfptr(sig, usig, attr->signature_size);
>> + if (err != 0)
>> + goto cleanup_sig;
>> +
>> + msg = pkcs7_parse_message(sig, attr->signature_size);
>> + if (IS_ERR(msg)) {
>> + *verdict = LSM_INT_VERDICT_BADSIG;
>> + err = 0;
>> + goto cleanup_sig;
>> + }
>> +
>> + if (system_keyring_id_check(attr->keyring_id) == 0)
>> + key = (struct key*)(unsigned long)attr->keyring_id;
>> + else
>> + key = key_ref_to_ptr(lookup_user_key(attr->keyring_id, 0, KEY_DEFER_PERM_CHECK));
>
> You might need to key_put the user key.
>
>> +
>> + if (verify_pkcs7_message_sig(prog->insnsi, prog->len * sizeof(struct bpf_insn), msg,
>> + key,
>> + VERIFYING_BPF_SIGNATURE,
>> + NULL, NULL)) {
>> + *verdict = LSM_INT_VERDICT_UNKNOWNKEY;
>> + err = 0;
>> + goto cleanup_msg;
>> + }
>> +
>> + if (pkcs7_get_authattr(msg, OID_hornet_data,
>> + &authattrs, &authattrs_len) == -ENODATA) {
>> + *verdict = LSM_INT_VERDICT_PARTIALSIG;
>> + err = 0;
>> + goto cleanup_msg;
>> + }
>> +
>> + err = asn1_ber_decoder(&hornet_decoder, ctx, authattrs, authattrs_len);
>> + if (err < 0 || authattrs == NULL) {
>> + *verdict = LSM_INT_VERDICT_BADSIG;
>> + err = 0;
>> + goto cleanup_msg;
>> + }
>> +
>> + err = hornet_verify_hashes(&maps, ctx, prog);
>> + if (err == 0)
>> + *verdict = LSM_INT_VERDICT_OK;
>> + else
>> + *verdict = err;
>> +
>> +cleanup_msg:
>> + pkcs7_free_message(msg);
>> +cleanup_sig:
>> + kfree(sig);
>> +out:
>> + kfree(ctx);
>> + return err;
>> +}
>> +
>> +static const struct lsm_id hornet_lsmid = {
>> + .name = "hornet",
>> + .id = LSM_ID_HORNET,
>> +};
>> +
>> +static int hornet_bpf_prog_load_integrity(struct bpf_prog *prog, union bpf_attr *attr,
>> + struct bpf_token *token, bool is_kernel)
>> +{
>> + enum lsm_integrity_verdict verdict;
>> + int result = hornet_check_program(prog, attr, token, is_kernel, &verdict);
>> +
>> + if (result < 0)
>> + return result;
>> +
>> + return security_bpf_prog_load_post_integrity(prog, attr, token, is_kernel,
>> + &hornet_lsmid, verdict);
>> +}
>> +
>> +static int hornet_verify_map(struct bpf_prog *prog, int index)
>> +{
>> + unsigned char hash[SHA256_DIGEST_SIZE];
>> + int i;
>> + struct bpf_map *map;
>> + struct hornet_prog_security_struct *security = hornet_bpf_prog_security(prog);
>> + struct hornet_map_security_struct *map_security;
>> +
>> + if (!security->checked[index])
>> + return 0;
>> +
>> + for (i = 0; i < prog->aux->used_map_cnt; i++) {
>> + map = prog->aux->used_maps[i];
>> + map_security = hornet_bpf_map_security(map);
>> + if (map_security->index != index)
>> + continue;
>> +
>> + if (!map->frozen)
>> + return -EPERM;
>> +
>> + map->ops->map_get_hash(map, SHA256_DIGEST_SIZE, hash);
>> + if (memcmp(hash, &security->hashes[index * SHA256_DIGEST_SIZE],
>> + SHA256_DIGEST_SIZE) != 0)
>> + return -EPERM;
>> + else
>> + return 0;
>> + }
>> + return -EINVAL;
>> +}
>> +
>> +static int hornet_check_prog_maps(u32 ufd)
>> +{
>> + CLASS(fd, f)(ufd);
>> + struct bpf_prog *prog;
>> + int i, result = 0;
>> +
>> + if (fd_empty(f))
>> + return -EBADF;
>> + if (fd_file(f)->f_op != &bpf_prog_fops)
>> + return -EINVAL;
>> +
>> + prog = fd_file(f)->private_data;
>> +
>> + mutex_lock(&prog->aux->used_maps_mutex);
>> + if (!prog->aux->used_map_cnt)
>> + goto out;
>> +
>> + for (i = 0; i < prog->aux->used_map_cnt; i++) {
>> + result = hornet_verify_map(prog, i);
>> + if (result)
>> + goto out;
>> + }
>
> This loop is kind of confusing for me, I guess it's just iterating
> through the maps the program currently in use. I feel the nested loop
> is unnecessary and the hash could be saved into the map's blob
> instead. Please correct me if I'm wrong here.
>
It turns out that we can. I'll send out the simplified version in v6.
> -Fan
>
>> +out:
>> + mutex_unlock(&prog->aux->used_maps_mutex);
>> + return result;
>> +}
>> +
>> +static int hornet_bpf(int cmd, union bpf_attr *attr, unsigned int size, bool kernel)
>> +{
>> + /* in horent_bpf(), anything that had originated from kernel space we assume
>> + has already been checked, in some form or another, so we don't bother
>> + checking the intergity of any maps. In hornet_bpf_prog_load_integrity(),
>> + hornet doesn't make any opinion on that and delegates that to the downstream
>> + policy enforcement. */
>> +
>> + if (cmd != BPF_PROG_RUN)
>> + return 0;
>> + if (kernel)
>> + return 0;
>> +
>> + return hornet_check_prog_maps(attr->test.prog_fd);
>> +}
>> +
>> +static struct security_hook_list hornet_hooks[] __ro_after_init = {
>> + LSM_HOOK_INIT(bpf_prog_load_integrity, hornet_bpf_prog_load_integrity),
>> + LSM_HOOK_INIT(bpf, hornet_bpf),
>> +};
>> +
>> +static int __init hornet_init(void)
>> +{
>> + pr_info("Hornet: eBPF signature verification enabled\n");
>> + security_add_hooks(hornet_hooks, ARRAY_SIZE(hornet_hooks), &hornet_lsmid);
>> + return 0;
>> +}
>> +
>> +DEFINE_LSM(hornet) = {
>> + .id = &hornet_lsmid,
>> + .blobs = &hornet_blob_sizes,
>> + .init = hornet_init,
>> +};
>> --
>> 2.53.0
>>
^ permalink raw reply
* [PATCH v5 01/13] ima: Remove ima_h_table structure
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
With the upcoming change of dynamically allocating and replacing the hash
table, the ima_h_table structure would have been replaced with a new one.
However, since the ima_h_table structure contains also the counters for
number of measurements entries and violations, we would have needed to
preserve their values in the new ima_h_table structure.
Instead, separate those counters from the hash table, remove the
ima_h_table structure, and just replace the hash table pointer.
Finally, rename ima_show_htable_value(), ima_show_htable_violations()
and ima_htable_violations_ops respectively to ima_show_counter(),
ima_show_num_violations() and ima_num_violations_ops.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima.h | 9 +++------
security/integrity/ima/ima_api.c | 2 +-
security/integrity/ima/ima_fs.c | 19 +++++++++----------
security/integrity/ima/ima_kexec.c | 2 +-
security/integrity/ima/ima_queue.c | 17 ++++++++++-------
5 files changed, 24 insertions(+), 25 deletions(-)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 69e9bf0b82c6..51a8a582df56 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -324,12 +324,9 @@ int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
*/
extern spinlock_t ima_queue_lock;
-struct ima_h_table {
- atomic_long_t len; /* number of stored measurements in the list */
- atomic_long_t violations;
- struct hlist_head queue[IMA_MEASURE_HTABLE_SIZE];
-};
-extern struct ima_h_table ima_htable;
+extern atomic_long_t ima_num_entries;
+extern atomic_long_t ima_num_violations;
+extern struct hlist_head ima_htable[IMA_MEASURE_HTABLE_SIZE];
static inline unsigned int ima_hash_key(u8 *digest)
{
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 0916f24f005f..122d127e108d 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -146,7 +146,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename,
int result;
/* can overflow, only indicator */
- atomic_long_inc(&ima_htable.violations);
+ atomic_long_inc(&ima_num_violations);
result = ima_alloc_init_template(&event_data, &entry, NULL);
if (result < 0) {
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index ca4931a95098..aaa460d70ff7 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -38,8 +38,8 @@ __setup("ima_canonical_fmt", default_canonical_fmt_setup);
static int valid_policy = 1;
-static ssize_t ima_show_htable_value(char __user *buf, size_t count,
- loff_t *ppos, atomic_long_t *val)
+static ssize_t ima_show_counter(char __user *buf, size_t count, loff_t *ppos,
+ atomic_long_t *val)
{
char tmpbuf[32]; /* greater than largest 'long' string value */
ssize_t len;
@@ -48,15 +48,14 @@ static ssize_t ima_show_htable_value(char __user *buf, size_t count,
return simple_read_from_buffer(buf, count, ppos, tmpbuf, len);
}
-static ssize_t ima_show_htable_violations(struct file *filp,
- char __user *buf,
- size_t count, loff_t *ppos)
+static ssize_t ima_show_num_violations(struct file *filp, char __user *buf,
+ size_t count, loff_t *ppos)
{
- return ima_show_htable_value(buf, count, ppos, &ima_htable.violations);
+ return ima_show_counter(buf, count, ppos, &ima_num_violations);
}
-static const struct file_operations ima_htable_violations_ops = {
- .read = ima_show_htable_violations,
+static const struct file_operations ima_num_violations_ops = {
+ .read = ima_show_num_violations,
.llseek = generic_file_llseek,
};
@@ -64,7 +63,7 @@ static ssize_t ima_show_measurements_count(struct file *filp,
char __user *buf,
size_t count, loff_t *ppos)
{
- return ima_show_htable_value(buf, count, ppos, &ima_htable.len);
+ return ima_show_counter(buf, count, ppos, &ima_num_entries);
}
@@ -545,7 +544,7 @@ int __init ima_fs_init(void)
}
dentry = securityfs_create_file("violations", S_IRUSR | S_IRGRP,
- ima_dir, NULL, &ima_htable_violations_ops);
+ ima_dir, NULL, &ima_num_violations_ops);
if (IS_ERR(dentry)) {
ret = PTR_ERR(dentry);
goto out;
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 36a34c54de58..5801649fbbef 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -43,7 +43,7 @@ void ima_measure_kexec_event(const char *event_name)
int n;
buf_size = ima_get_binary_runtime_size();
- len = atomic_long_read(&ima_htable.len);
+ len = atomic_long_read(&ima_num_entries);
n = scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN,
"kexec_segment_size=%lu;ima_binary_runtime_size=%lu;"
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 319522450854..1f6515f7d015 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -32,11 +32,14 @@ static unsigned long binary_runtime_size;
static unsigned long binary_runtime_size = ULONG_MAX;
#endif
+/* num of stored measurements in the list */
+atomic_long_t ima_num_entries = ATOMIC_LONG_INIT(0);
+/* num of violations in the list */
+atomic_long_t ima_num_violations = ATOMIC_LONG_INIT(0);
+
/* key: inode (before secure-hashing a file) */
-struct ima_h_table ima_htable = {
- .len = ATOMIC_LONG_INIT(0),
- .violations = ATOMIC_LONG_INIT(0),
- .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
+struct hlist_head ima_htable[IMA_MEASURE_HTABLE_SIZE] = {
+ [0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
};
/* mutex protects atomicity of extending measurement list
@@ -61,7 +64,7 @@ static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
key = ima_hash_key(digest_value);
rcu_read_lock();
- hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) {
+ hlist_for_each_entry_rcu(qe, &ima_htable[key], hnext) {
rc = memcmp(qe->entry->digests[ima_hash_algo_idx].digest,
digest_value, hash_digest_size[ima_hash_algo]);
if ((rc == 0) && (qe->entry->pcr == pcr)) {
@@ -113,10 +116,10 @@ static int ima_add_digest_entry(struct ima_template_entry *entry,
INIT_LIST_HEAD(&qe->later);
list_add_tail_rcu(&qe->later, &ima_measurements);
- atomic_long_inc(&ima_htable.len);
+ atomic_long_inc(&ima_num_entries);
if (update_htable) {
key = ima_hash_key(entry->digests[ima_hash_algo_idx].digest);
- hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
+ hlist_add_head_rcu(&qe->hnext, &ima_htable[key]);
}
if (binary_runtime_size != ULONG_MAX) {
--
2.43.0
^ permalink raw reply related
* [PATCH v5 13/13] doc: security: Add documentation of the IMA staging mechanism
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Add the documentation of the IMA staging mechanism in
Documentation/security/IMA-staging.rst.
Also add the missing Documentation/security/IMA-templates.rst file in
MAINTAINERS.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
Documentation/security/IMA-staging.rst | 163 +++++++++++++++++++++++++
Documentation/security/index.rst | 1 +
MAINTAINERS | 2 +
3 files changed, 166 insertions(+)
create mode 100644 Documentation/security/IMA-staging.rst
diff --git a/Documentation/security/IMA-staging.rst b/Documentation/security/IMA-staging.rst
new file mode 100644
index 000000000000..de6428893f0e
--- /dev/null
+++ b/Documentation/security/IMA-staging.rst
@@ -0,0 +1,163 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==================================
+IMA Measurements Staging Mechanism
+==================================
+
+
+Introduction
+============
+
+The IMA measurements list is currently stored in the kernel memory. Memory
+occupation grows linearly with the number of entries, and can become a
+problem especially in environments with reduced resources.
+
+While there is an advantage in keeping the IMA measurements list in kernel
+memory, so that it is always available for reading from the securityfs
+interfaces, storing it elsewhere would make it possible to free precious
+memory for other kernel components.
+
+Storing the IMA measurements list outside the kernel does not introduce
+security issues, since its integrity is anyway protected by the TPM.
+
+Hence, the new IMA staging mechanism is introduced to allow user space
+to remove the desired portion of the measurements list from the kernel.
+
+
+Usage
+=====
+
+The IMA staging mechanism can be enabled from the kernel configuration with
+the CONFIG_IMA_STAGING option.
+
+If it is enabled, IMA duplicates the current measurements interfaces (both
+binary and ASCII), by adding the ``_staged`` file suffix. Both the original
+and the staging interfaces gain the write permission for the root user and
+group, but require the process to have CAP_SYS_ADMIN set.
+
+The staging mechanism supports two flavors.
+
+
+Staging with prompt
+~~~~~~~~~~~~~~~~~~~
+
+The current measurements list is moved to a temporary staging area, and
+staged measurements are deleted upon confirmation.
+
+This staging process is achieved with the following steps.
+
+ 1. ``echo A > <original interface>``: the user requests IMA to stage the
+ entire measurements list;
+ 2. ``cat <_staged interface>``: the user reads the staged measurements;
+ 3. ``echo D > <_staged interface>``: the user requests IMA to delete
+ staged measurements.
+
+
+Staging and deleting
+~~~~~~~~~~~~~~~~~~~~
+
+N measurements are staged to a temporary staging area, and immediately
+deleted without further confirmation.
+
+This staging process is achieved with the following steps.
+
+ 1. ``cat <original interface>``: the user reads the current measurements
+ list and determines what the value N for staging should be;
+ 2. ``echo N > <original interface>``: the user requests IMA to delete N
+ measurements from the current measurements list.
+
+
+Interface Access
+================
+
+In order to avoid the IMA measurements list be suddenly truncated by the
+staging mechanism during a read, or having multiple concurrent staging, a
+semaphore-like locking scheme has been implemented on all the measurements
+list interfaces.
+
+Multiple readers can access concurrently the original and staged
+interfaces, and they can be in mutual exclusion with one writer.
+
+If an illegal access occurs, the open to the measurements list interface is
+denied.
+
+
+Management of Staged Measurements
+=================================
+
+Since with the staging mechanism measurement entries are removed from the
+kernel, the user needs to save the staged ones in a storage and concatenate
+them together, so that it can present them to remote attestation agents as
+if staging was never done.
+
+Coordination is necessary in the case where there are multiple actors
+requesting measurements to be staged.
+
+In the staging with prompt case, the measurement interfaces can be accessed
+only by one actor (writer) at a time, so the others will get an error until
+the former closes it. Since the actors don't care about N, when they gain
+access to the interface, they will get all the staged measurements at the
+time of their request.
+
+In the case of staging and deleting, coordination is more important, since
+there is the risk that two actors unaware of each other compute the value N
+on the current measurements list and request IMA to stage N twice.
+
+
+Remote Attestation Agent Workflow
+=================================
+
+Users can choose the staging method they find more appropriate for their
+workflow.
+
+If, as an example, a remote attestation agent would like to present to the
+remote attestation server only the measurements that are required to
+verify the TPM quote, its workflow would be the following.
+
+With staging with prompt, the agent stages the current measurements list,
+reads and stores the measurements in a storage and immediately requests
+IMA to delete the staged measurements from kernel memory. Afterwards, it
+calculates N by replaying the PCR extend on the stored measurements until
+the calculated PCRs match the quoted PCRs. It then keeps the measurements
+in excess for the next attestation request.
+
+At the next attestation request, the agent performs the same steps above,
+and concatenates the new measurements to the ones in excess from the
+previous request. Also in this case, the agent replays the PCR extend until
+it matches the currently quoted PCRs, keeps the measurements in excess and
+presents the new N measurements entries to the remote attestation server.
+
+With the staging and deleting method, the agent reads the current
+measurements list, calculates N and requests IMA to delete only those. The
+measurements in excess are kept in the IMA measurements list and can be
+retrieved at the next remote attestation request.
+
+Kexec
+=====
+
+In the event a kexec() system call occurs between staging and deleting, the
+staged measurements entries are prepended to the current measurements list,
+so that they are both available when the secondary kernel starts. In that
+case, IMA returns an error to the user when attempting to delete staged
+measurements to notify about their copy to the kexec buffer, so that the
+user does not store them twice.
+
+
+Hash table
+==========
+
+By default, the template digest of staged measurement entries are kept in
+kernel memory (only template data are freed), to be able to detect
+duplicate entries independently of staging.
+
+The new kernel option ``ima_flush_htable`` has been introduced to
+explicitly request a complete deletion of the staged measurements, for
+maximum kernel memory saving. If the option has been specified, duplicate
+entries are still avoided on entries of the current measurements list,
+but there can be duplicates between different groups of staged
+measurements.
+
+Flushing the hash table is supported only for the staging with prompt
+flavor. For the staging and deleting flavor, it would have been necessary
+to lock the hot path adding new measurements for the time needed to remove
+each selected measurement individually.
diff --git a/Documentation/security/index.rst b/Documentation/security/index.rst
index 3e0a7114a862..cec064dc1c83 100644
--- a/Documentation/security/index.rst
+++ b/Documentation/security/index.rst
@@ -8,6 +8,7 @@ Security Documentation
credentials
snp-tdx-threat-model
IMA-templates
+ IMA-staging
keys/index
lsm
lsm-development
diff --git a/MAINTAINERS b/MAINTAINERS
index 2fb1c75afd16..5bc816ab4a5b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12740,6 +12740,8 @@ R: Eric Snowberg <eric.snowberg@oracle.com>
L: linux-integrity@vger.kernel.org
S: Supported
T: git git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.git
+F: Documentation/security/IMA-staging.rst
+F: Documentation/security/IMA-templates.rst
F: include/linux/secure_boot.h
F: security/integrity/
F: security/integrity/ima/
--
2.43.0
^ permalink raw reply related
* [PATCH v5 12/13] ima: Return error on deleting measurements already copied during kexec
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Refuse to delete staged or active list measurements, if a kexec racing with
the deletion already copied those measurements in the kexec buffer. In this
way, user space becomes aware that those measurements are going to appear
in the secondary kernel, and thus they don't have to be saved twice.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima.h | 5 +++++
security/integrity/ima/ima_kexec.c | 6 ++++++
security/integrity/ima/ima_queue.c | 17 +++++++++++++++++
3 files changed, 28 insertions(+)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 9a741b33d524..9be4c35d7ec1 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -344,6 +344,11 @@ extern struct hlist_head __rcu *ima_htable;
extern struct mutex ima_extend_list_mutex;
extern bool ima_flush_htable;
+#define IMA_MEASUREMENTS_STAGED_COPIED 1
+#define IMA_MEASUREMENTS_COPIED 2
+
+extern u8 ima_copied_flags;
+
static inline unsigned int ima_hash_key(u8 *digest)
{
/* there is no point in taking a hash of part of a digest */
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index e7bde3d917b2..5c7abde114f2 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -119,6 +119,9 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
break;
}
+ if (!list_empty(&ima_measurements_staged))
+ ima_copied_flags |= IMA_MEASUREMENTS_STAGED_COPIED;
+
list_for_each_entry_rcu(qe, &ima_measurements, later,
lockdep_is_held(&ima_extend_list_mutex)) {
if (!ret)
@@ -127,6 +130,9 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
break;
}
+ if (!list_empty(&ima_measurements))
+ ima_copied_flags |= IMA_MEASUREMENTS_COPIED;
+
mutex_unlock(&ima_extend_list_mutex);
/*
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 64c4fe73dd5f..7f09cce53772 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -72,6 +72,13 @@ DEFINE_MUTEX(ima_extend_list_mutex);
*/
static bool ima_measurements_suspended;
+/*
+ * Used to determine if staged or active list measurements were copied during
+ * kexec, so that an error can be sent to user space during deletion, and they
+ * don't store those measurements twice.
+ */
+u8 ima_copied_flags;
+
/* Callers must call synchronize_rcu() and free the hash table. */
static struct hlist_head *ima_alloc_replace_htable(void)
{
@@ -344,6 +351,11 @@ int ima_queue_staged_delete_all(void)
return -ENOENT;
}
+ if (ima_copied_flags & IMA_MEASUREMENTS_STAGED_COPIED) {
+ mutex_unlock(&ima_extend_list_mutex);
+ return -ESTALE;
+ }
+
list_replace(&ima_measurements_staged, &ima_measurements_trim);
INIT_LIST_HEAD(&ima_measurements_staged);
@@ -397,6 +409,11 @@ int ima_queue_delete_partial(unsigned long req_value)
return -ENOENT;
mutex_lock(&ima_extend_list_mutex);
+ if (ima_copied_flags & IMA_MEASUREMENTS_COPIED) {
+ mutex_unlock(&ima_extend_list_mutex);
+ return -ESTALE;
+ }
+
/*
* qe remains valid because ima_fs.c enforces single-writer exclusion.
*/
--
2.43.0
^ permalink raw reply related
* [PATCH v5 11/13] ima: Support staging and deleting N measurements entries
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Add support for sending a value N between 1 and ULONG_MAX to the IMA
original measurement interface. This value represents the number of
measurements that should be deleted from the current measurements list. In
this case, measurements are staged in an internal non-user visible list,
and immediately deleted.
This staging method allows the remote attestation agents to easily separate
the measurements that were verified (staged and deleted) from those that
weren't due to the race between taking a TPM quote and reading the
measurements list.
In order to minimize the locking time of ima_extend_list_mutex, deleting
N entries is realized by doing a lockless walk in the current measurements
list to determine the N-th entry to cut, to cut the current measurements
list under the lock, and by deleting the excess entries after releasing the
lock.
Flushing the hash table is not supported for N entries, since it would
require removing the N entries one by one from the hash table under the
ima_extend_list_mutex lock, which would increase the locking time.
The ima_extend_list_mutex lock is necessary in ima_dump_measurement_list()
because ima_queue_delete_partial() uses __list_cut_position() to modify
ima_measurements, for which no RCU-safe variant exists. For the staging
with prompt flavor alone, list_replace_rcu() could have been used instead,
but since both flavors share the same kexec serialization path, the mutex
is required regardless.
Link: https://github.com/linux-integrity/linux/issues/1
Suggested-by: Steven Chen <chenste@linux.microsoft.com>
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/Kconfig | 3 +++
security/integrity/ima/ima.h | 1 +
security/integrity/ima/ima_fs.c | 21 ++++++++++++++-
security/integrity/ima/ima_kexec.c | 3 ++-
security/integrity/ima/ima_queue.c | 43 ++++++++++++++++++++++++++++++
5 files changed, 69 insertions(+), 2 deletions(-)
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 48c906793efb..4f4373859a4f 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -341,6 +341,9 @@ config IMA_STAGING
It allows user space to stage the measurements list for deletion and
to delete the staged measurements after confirmation.
+ Or, alternatively, it allows user space to specify N measurements
+ entries to stage internally, so that they can be immediately deleted.
+
On kexec, staging is reverted and staged measurements are prepended
to the current measurements list when measurements are copied to the
secondary kernel.
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 4af66c1de4dc..9a741b33d524 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -320,6 +320,7 @@ struct ima_template_desc *lookup_template_desc(const char *name);
bool ima_template_has_modsig(const struct ima_template_desc *ima_template);
int ima_queue_stage(void);
int ima_queue_staged_delete_all(void);
+int ima_queue_delete_partial(unsigned long req_value);
int ima_restore_measurement_entry(struct ima_template_entry *entry);
int ima_restore_measurement_list(loff_t bufsize, void *buf);
int ima_measurements_show(struct seq_file *m, void *v);
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 088d5a69aa92..6843dc203b54 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -28,6 +28,7 @@
* Requests:
* 'A\n': stage the entire measurements list
* 'D\n': delete all staged measurements
+ * '[1, ULONG_MAX]\n' delete N measurements entries
*/
#define STAGED_REQ_LENGTH 21
@@ -312,6 +313,7 @@ static ssize_t _ima_measurements_write(struct file *file,
loff_t *ppos, bool staged_interface)
{
char req[STAGED_REQ_LENGTH];
+ unsigned long req_value;
int ret;
if (*ppos > 0 || datalen < 2 || datalen > STAGED_REQ_LENGTH)
@@ -339,7 +341,24 @@ static ssize_t _ima_measurements_write(struct file *file,
ret = ima_queue_staged_delete_all();
break;
default:
- ret = -EINVAL;
+ if (staged_interface)
+ return -EINVAL;
+
+ if (ima_flush_htable) {
+ pr_debug("Deleting staged N measurements not supported when flushing the hash table is requested\n");
+ return -EINVAL;
+ }
+
+ ret = kstrtoul(req, 10, &req_value);
+ if (ret < 0)
+ return ret;
+
+ if (req_value == 0) {
+ pr_debug("Must delete at least one entry\n");
+ return -EINVAL;
+ }
+
+ ret = ima_queue_delete_partial(req_value);
}
if (ret < 0)
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 064cfce0c318..e7bde3d917b2 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -107,7 +107,8 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
memset(&khdr, 0, sizeof(khdr));
khdr.version = 1;
/*
- * It can race with ima_queue_stage() and ima_queue_staged_delete_all().
+ * It can race with ima_queue_stage(), ima_queue_staged_delete_all()
+ * and ima_queue_delete_partial().
*/
mutex_lock(&ima_extend_list_mutex);
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index f5c18acfbc43..64c4fe73dd5f 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -371,6 +371,49 @@ int ima_queue_staged_delete_all(void)
return 0;
}
+int ima_queue_delete_partial(unsigned long req_value)
+{
+ unsigned long req_value_copy = req_value;
+ unsigned long size_to_remove = 0, num_to_remove = 0;
+ LIST_HEAD(ima_measurements_trim);
+ struct ima_queue_entry *qe;
+ int ret = 0;
+
+ /*
+ * Safe to walk without rcu_read_lock(): single-writer
+ * exclusion in ima_fs.c prevents any concurrent modification
+ * to ima_measurements during this walk.
+ */
+ list_for_each_entry_rcu(qe, &ima_measurements, later, true) {
+ size_to_remove += get_binary_runtime_size(qe->entry);
+ num_to_remove++;
+
+ if (--req_value_copy == 0)
+ break;
+ }
+
+ /* Not enough entries to delete. */
+ if (req_value_copy > 0)
+ return -ENOENT;
+
+ mutex_lock(&ima_extend_list_mutex);
+ /*
+ * qe remains valid because ima_fs.c enforces single-writer exclusion.
+ */
+ __list_cut_position(&ima_measurements_trim, &ima_measurements,
+ &qe->later);
+
+ atomic_long_sub(num_to_remove, &ima_num_entries[BINARY]);
+
+ if (IS_ENABLED(CONFIG_IMA_KEXEC))
+ binary_runtime_size[BINARY] -= size_to_remove;
+
+ mutex_unlock(&ima_extend_list_mutex);
+
+ ima_queue_delete(&ima_measurements_trim, false);
+ return ret;
+}
+
static void ima_queue_delete(struct list_head *head, bool flush_htable)
{
struct ima_queue_entry *qe, *qe_tmp;
--
2.43.0
^ permalink raw reply related
* [PATCH v5 10/13] ima: Add support for flushing the hash table when staging measurements
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Introduce the new kernel option ima_flush_htable to decide whether or not
the digests of staged measurement entries are flushed from the hash table,
when they are deleted.
When the option is enabled, replace the old hash table with a new one,
by calling ima_alloc_replace_htable(), and completely delete the
measurements entries.
Note: This code derives from the Alt-IMA Huawei project, whose license is
GPL-2.0 OR MIT.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
.../admin-guide/kernel-parameters.txt | 4 +++
security/integrity/ima/ima.h | 1 +
security/integrity/ima/ima_queue.c | 36 ++++++++++++++++---
3 files changed, 37 insertions(+), 4 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 4d0f545fb3ec..56efb8bfcc4e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2343,6 +2343,10 @@ Kernel parameters
Use the canonical format for the binary runtime
measurements, instead of host native format.
+ ima_flush_htable [IMA]
+ Flush the IMA hash table when deleting all the
+ staged measurement entries.
+
ima_hash= [IMA]
Format: { md5 | sha1 | rmd160 | sha256 | sha384
| sha512 | ... }
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index ca8fa43ec72b..4af66c1de4dc 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -341,6 +341,7 @@ extern atomic_long_t ima_num_entries[BINARY__LAST];
extern atomic_long_t ima_num_violations;
extern struct hlist_head __rcu *ima_htable;
extern struct mutex ima_extend_list_mutex;
+extern bool ima_flush_htable;
static inline unsigned int ima_hash_key(u8 *digest)
{
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 50519ed837d4..f5c18acfbc43 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -22,6 +22,20 @@
#define AUDIT_CAUSE_LEN_MAX 32
+bool ima_flush_htable;
+
+static int __init ima_flush_htable_setup(char *str)
+{
+ if (IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE)) {
+ pr_warn("Hash table not enabled, ignoring request to flush\n");
+ return 1;
+ }
+
+ ima_flush_htable = true;
+ return 1;
+}
+__setup("ima_flush_htable", ima_flush_htable_setup);
+
/* pre-allocated array of tpm_digest structures to extend a PCR */
static struct tpm_digest *digests;
@@ -317,10 +331,11 @@ int ima_queue_stage(void)
return ret;
}
-static void ima_queue_delete(struct list_head *head);
+static void ima_queue_delete(struct list_head *head, bool flush_htable);
int ima_queue_staged_delete_all(void)
{
+ struct hlist_head *old_queue = NULL;
LIST_HEAD(ima_measurements_trim);
mutex_lock(&ima_extend_list_mutex);
@@ -337,13 +352,26 @@ int ima_queue_staged_delete_all(void)
if (IS_ENABLED(CONFIG_IMA_KEXEC))
binary_runtime_size[BINARY_STAGED] = 0;
+ if (ima_flush_htable) {
+ old_queue = ima_alloc_replace_htable();
+ if (IS_ERR(old_queue)) {
+ mutex_unlock(&ima_extend_list_mutex);
+ return PTR_ERR(old_queue);
+ }
+ }
+
mutex_unlock(&ima_extend_list_mutex);
- ima_queue_delete(&ima_measurements_trim);
+ if (ima_flush_htable) {
+ synchronize_rcu();
+ kfree(old_queue);
+ }
+
+ ima_queue_delete(&ima_measurements_trim, ima_flush_htable);
return 0;
}
-static void ima_queue_delete(struct list_head *head)
+static void ima_queue_delete(struct list_head *head, bool flush_htable)
{
struct ima_queue_entry *qe, *qe_tmp;
unsigned int i;
@@ -365,7 +393,7 @@ static void ima_queue_delete(struct list_head *head)
list_del(&qe->later);
/* No leak if condition is false, referenced by ima_htable. */
- if (IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE)) {
+ if (IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE) || flush_htable) {
kfree(qe->entry->digests);
kfree(qe->entry);
kfree(qe);
--
2.43.0
^ permalink raw reply related
* [PATCH v5 09/13] ima: Add support for staging measurements with prompt
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Introduce the ability of staging the IMA measurement list and deleting them
with a prompt.
Staging means moving the current content of the measurement list to a
separate location, and allowing users to read and delete it. This causes
the measurement list to be atomically truncated before new measurements can
be added. Staging can be done only once at a time. In the event of kexec(),
staging is reverted and staged entries will be carried over to the new
kernel.
Introduce ascii_runtime_measurements_<algo>_staged and
binary_runtime_measurements_<algo>_staged interfaces to access and delete
the measurements. Also, add write permission to the original measurement
interfaces.
Use 'echo A > <IMA original interface>' and
'echo D > <IMA _staged interface>' to respectively stage and delete the
entire measurements list. Locking of these interfaces is also mediated with
a call to _ima_measurements_open() and with ima_measurements_release().
Implement the staging functionality by introducing the new global
measurements list ima_measurements_staged, and ima_queue_stage() and
ima_queue_staged_delete_all() to respectively move measurements from the
current measurements list to the staged one, and to move staged
measurements to the ima_measurements_trim list for deletion. Introduce
ima_queue_delete() to delete the measurements.
Finally, introduce the BINARY_STAGED and BINARY_FULL binary measurements
list types, to maintain the counters and the binary size of staged
measurements and the full measurements list (including entries that were
staged). BINARY still represents the current binary measurements list.
Use the binary size for the BINARY + BINARY_STAGED types in
ima_add_kexec_buffer(), since both measurements list types are copied to
the secondary kernel during kexec. Use BINARY_FULL in
ima_measure_kexec_event(), to generate a critical data record.
It should be noted that the BINARY_FULL counter is not passed through
kexec. Thus, the number of entries included in the kexec critical data
records refers to the entries since the previous kexec records.
Note: This code derives from the Alt-IMA Huawei project, whose license is
GPL-2.0 OR MIT.
Link: https://github.com/linux-integrity/linux/issues/1
Suggested-by: Gregory Lumen <gregorylumen@linux.microsoft.com> (staging revert)
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/Kconfig | 13 +++
security/integrity/ima/ima.h | 8 +-
security/integrity/ima/ima_fs.c | 181 ++++++++++++++++++++++++++---
security/integrity/ima/ima_kexec.c | 24 +++-
security/integrity/ima/ima_queue.c | 97 +++++++++++++++-
5 files changed, 302 insertions(+), 21 deletions(-)
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 862fbee2b174..48c906793efb 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -332,4 +332,17 @@ config IMA_KEXEC_EXTRA_MEMORY_KB
If set to the default value of 0, an extra half page of memory for those
additional measurements will be allocated.
+config IMA_STAGING
+ bool "Support for staging the measurements list"
+ default y
+ help
+ Add support for staging the measurements list.
+
+ It allows user space to stage the measurements list for deletion and
+ to delete the staged measurements after confirmation.
+
+ On kexec, staging is reverted and staged measurements are prepended
+ to the current measurements list when measurements are copied to the
+ secondary kernel.
+
endif
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index f8ab6b604c0d..ca8fa43ec72b 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -30,9 +30,11 @@ enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8, TPM_PCR10 = 10 };
/*
* BINARY: current binary measurements list
+ * BINARY_STAGED: staged binary measurements list
+ * BINARY_FULL: binary measurements list since IMA init (lost after kexec)
*/
enum binary_lists {
- BINARY, BINARY__LAST
+ BINARY, BINARY_STAGED, BINARY_FULL, BINARY__LAST
};
/* digest size for IMA, fits SHA1 or MD5 */
@@ -125,6 +127,7 @@ struct ima_queue_entry {
struct ima_template_entry *entry;
};
extern struct list_head ima_measurements; /* list of all measurements */
+extern struct list_head ima_measurements_staged; /* list of staged meas. */
/* Some details preceding the binary serialized measurement list */
struct ima_kexec_hdr {
@@ -315,6 +318,8 @@ struct ima_template_desc *ima_template_desc_current(void);
struct ima_template_desc *ima_template_desc_buf(void);
struct ima_template_desc *lookup_template_desc(const char *name);
bool ima_template_has_modsig(const struct ima_template_desc *ima_template);
+int ima_queue_stage(void);
+int ima_queue_staged_delete_all(void);
int ima_restore_measurement_entry(struct ima_template_entry *entry);
int ima_restore_measurement_list(loff_t bufsize, void *buf);
int ima_measurements_show(struct seq_file *m, void *v);
@@ -335,6 +340,7 @@ extern spinlock_t ima_queue_lock;
extern atomic_long_t ima_num_entries[BINARY__LAST];
extern atomic_long_t ima_num_violations;
extern struct hlist_head __rcu *ima_htable;
+extern struct mutex ima_extend_list_mutex;
static inline unsigned int ima_hash_key(u8 *digest)
{
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 7709a4576322..088d5a69aa92 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -24,6 +24,13 @@
#include "ima.h"
+/*
+ * Requests:
+ * 'A\n': stage the entire measurements list
+ * 'D\n': delete all staged measurements
+ */
+#define STAGED_REQ_LENGTH 21
+
static DEFINE_MUTEX(ima_write_mutex);
static DEFINE_MUTEX(ima_measure_mutex);
static long ima_measure_users;
@@ -97,6 +104,11 @@ static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
return _ima_measurements_start(m, pos, &ima_measurements);
}
+static void *ima_measurements_staged_start(struct seq_file *m, loff_t *pos)
+{
+ return _ima_measurements_start(m, pos, &ima_measurements_staged);
+}
+
static void *_ima_measurements_next(struct seq_file *m, void *v, loff_t *pos,
struct list_head *head)
{
@@ -118,6 +130,12 @@ static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
return _ima_measurements_next(m, v, pos, &ima_measurements);
}
+static void *ima_measurements_staged_next(struct seq_file *m, void *v,
+ loff_t *pos)
+{
+ return _ima_measurements_next(m, v, pos, &ima_measurements_staged);
+}
+
static void ima_measurements_stop(struct seq_file *m, void *v)
{
}
@@ -211,6 +229,13 @@ static const struct seq_operations ima_measurments_seqops = {
.show = ima_measurements_show
};
+static const struct seq_operations ima_measurments_staged_seqops = {
+ .start = ima_measurements_staged_start,
+ .next = ima_measurements_staged_next,
+ .stop = ima_measurements_stop,
+ .show = ima_measurements_show
+};
+
static int ima_measure_lock(bool write)
{
mutex_lock(&ima_measure_mutex);
@@ -276,9 +301,78 @@ static int ima_measurements_release(struct inode *inode, struct file *file)
return ret;
}
+static int ima_measurements_staged_open(struct inode *inode, struct file *file)
+{
+ return _ima_measurements_open(inode, file,
+ &ima_measurments_staged_seqops);
+}
+
+static ssize_t _ima_measurements_write(struct file *file,
+ const char __user *buf, size_t datalen,
+ loff_t *ppos, bool staged_interface)
+{
+ char req[STAGED_REQ_LENGTH];
+ int ret;
+
+ if (*ppos > 0 || datalen < 2 || datalen > STAGED_REQ_LENGTH)
+ return -EINVAL;
+
+ if (copy_from_user(req, buf, datalen) != 0)
+ return -EFAULT;
+
+ if (req[datalen - 1] != '\n')
+ return -EINVAL;
+
+ req[datalen - 1] = '\0';
+
+ switch (req[0]) {
+ case 'A':
+ if (datalen != 2 || staged_interface)
+ return -EINVAL;
+
+ ret = ima_queue_stage();
+ break;
+ case 'D':
+ if (datalen != 2 || !staged_interface)
+ return -EINVAL;
+
+ ret = ima_queue_staged_delete_all();
+ break;
+ default:
+ ret = -EINVAL;
+ }
+
+ if (ret < 0)
+ return ret;
+
+ return datalen;
+}
+
+static ssize_t ima_measurements_write(struct file *file, const char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ return _ima_measurements_write(file, buf, datalen, ppos, false);
+}
+
+static ssize_t ima_measurements_staged_write(struct file *file,
+ const char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ return _ima_measurements_write(file, buf, datalen, ppos, true);
+}
+
static const struct file_operations ima_measurements_ops = {
.open = ima_measurements_open,
.read = seq_read,
+ .write = ima_measurements_write,
+ .llseek = seq_lseek,
+ .release = ima_measurements_release,
+};
+
+static const struct file_operations ima_measurements_staged_ops = {
+ .open = ima_measurements_staged_open,
+ .read = seq_read,
+ .write = ima_measurements_staged_write,
.llseek = seq_lseek,
.release = ima_measurements_release,
};
@@ -352,6 +446,29 @@ static int ima_ascii_measurements_open(struct inode *inode, struct file *file)
static const struct file_operations ima_ascii_measurements_ops = {
.open = ima_ascii_measurements_open,
.read = seq_read,
+ .write = ima_measurements_write,
+ .llseek = seq_lseek,
+ .release = ima_measurements_release,
+};
+
+static const struct seq_operations ima_ascii_measurements_staged_seqops = {
+ .start = ima_measurements_staged_start,
+ .next = ima_measurements_staged_next,
+ .stop = ima_measurements_stop,
+ .show = ima_ascii_measurements_show
+};
+
+static int ima_ascii_measurements_staged_open(struct inode *inode,
+ struct file *file)
+{
+ return _ima_measurements_open(inode, file,
+ &ima_ascii_measurements_staged_seqops);
+}
+
+static const struct file_operations ima_ascii_measurements_staged_ops = {
+ .open = ima_ascii_measurements_staged_open,
+ .read = seq_read,
+ .write = ima_measurements_staged_write,
.llseek = seq_lseek,
.release = ima_measurements_release,
};
@@ -459,10 +576,20 @@ static const struct seq_operations ima_policy_seqops = {
};
#endif
-static int __init create_securityfs_measurement_lists(void)
+static int __init create_securityfs_measurement_lists(bool staging)
{
+ const struct file_operations *ascii_ops = &ima_ascii_measurements_ops;
+ const struct file_operations *binary_ops = &ima_measurements_ops;
+ mode_t permissions = (S_IRUSR | S_IRGRP | S_IWUSR | S_IWGRP);
+ const char *file_suffix = "";
int count = NR_BANKS(ima_tpm_chip);
+ if (staging) {
+ ascii_ops = &ima_ascii_measurements_staged_ops;
+ binary_ops = &ima_measurements_staged_ops;
+ file_suffix = "_staged";
+ }
+
if (ima_sha1_idx >= NR_BANKS(ima_tpm_chip))
count++;
@@ -473,29 +600,32 @@ static int __init create_securityfs_measurement_lists(void)
if (algo == HASH_ALGO__LAST)
snprintf(file_name, sizeof(file_name),
- "ascii_runtime_measurements_tpm_alg_%x",
- ima_tpm_chip->allocated_banks[i].alg_id);
+ "ascii_runtime_measurements_tpm_alg_%x%s",
+ ima_tpm_chip->allocated_banks[i].alg_id,
+ file_suffix);
else
snprintf(file_name, sizeof(file_name),
- "ascii_runtime_measurements_%s",
- hash_algo_name[algo]);
- dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
+ "ascii_runtime_measurements_%s%s",
+ hash_algo_name[algo], file_suffix);
+ dentry = securityfs_create_file(file_name, permissions,
ima_dir, (void *)(uintptr_t)i,
- &ima_ascii_measurements_ops);
+ ascii_ops);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
if (algo == HASH_ALGO__LAST)
snprintf(file_name, sizeof(file_name),
- "binary_runtime_measurements_tpm_alg_%x",
- ima_tpm_chip->allocated_banks[i].alg_id);
+ "binary_runtime_measurements_tpm_alg_%x%s",
+ ima_tpm_chip->allocated_banks[i].alg_id,
+ file_suffix);
else
snprintf(file_name, sizeof(file_name),
- "binary_runtime_measurements_%s",
- hash_algo_name[algo]);
- dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
+ "binary_runtime_measurements_%s%s",
+ hash_algo_name[algo], file_suffix);
+
+ dentry = securityfs_create_file(file_name, permissions,
ima_dir, (void *)(uintptr_t)i,
- &ima_measurements_ops);
+ binary_ops);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
}
@@ -503,6 +633,23 @@ static int __init create_securityfs_measurement_lists(void)
return 0;
}
+static int __init create_securityfs_staging_links(void)
+{
+ struct dentry *dentry;
+
+ dentry = securityfs_create_symlink("binary_runtime_measurements_staged",
+ ima_dir, "binary_runtime_measurements_sha1_staged", NULL);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ dentry = securityfs_create_symlink("ascii_runtime_measurements_staged",
+ ima_dir, "ascii_runtime_measurements_sha1_staged", NULL);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ return 0;
+}
+
/*
* ima_open_policy: sequentialize access to the policy file
*/
@@ -595,7 +742,13 @@ int __init ima_fs_init(void)
goto out;
}
- ret = create_securityfs_measurement_lists();
+ ret = create_securityfs_measurement_lists(false);
+ if (ret == 0 && IS_ENABLED(CONFIG_IMA_STAGING)) {
+ ret = create_securityfs_measurement_lists(true);
+ if (ret == 0)
+ ret = create_securityfs_staging_links();
+ }
+
if (ret != 0)
goto out;
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index d7d0fb639d99..064cfce0c318 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -42,8 +42,8 @@ void ima_measure_kexec_event(const char *event_name)
long len;
int n;
- buf_size = ima_get_binary_runtime_size(BINARY);
- len = atomic_long_read(&ima_num_entries[BINARY]);
+ buf_size = ima_get_binary_runtime_size(BINARY_FULL);
+ len = atomic_long_read(&ima_num_entries[BINARY_FULL]);
n = scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN,
"kexec_segment_size=%lu;ima_binary_runtime_size=%lu;"
@@ -106,13 +106,28 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
memset(&khdr, 0, sizeof(khdr));
khdr.version = 1;
- /* This is an append-only list, no need to hold the RCU read lock */
- list_for_each_entry_rcu(qe, &ima_measurements, later, true) {
+ /*
+ * It can race with ima_queue_stage() and ima_queue_staged_delete_all().
+ */
+ mutex_lock(&ima_extend_list_mutex);
+
+ list_for_each_entry_rcu(qe, &ima_measurements_staged, later,
+ lockdep_is_held(&ima_extend_list_mutex)) {
ret = ima_dump_measurement(&khdr, qe);
if (ret < 0)
break;
}
+ list_for_each_entry_rcu(qe, &ima_measurements, later,
+ lockdep_is_held(&ima_extend_list_mutex)) {
+ if (!ret)
+ ret = ima_dump_measurement(&khdr, qe);
+ if (ret < 0)
+ break;
+ }
+
+ mutex_unlock(&ima_extend_list_mutex);
+
/*
* fill in reserved space with some buffer details
* (eg. version, buffer size, number of measurements)
@@ -167,6 +182,7 @@ void ima_add_kexec_buffer(struct kimage *image)
extra_memory = CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB * 1024;
binary_runtime_size = ima_get_binary_runtime_size(BINARY) +
+ ima_get_binary_runtime_size(BINARY_STAGED) +
extra_memory;
if (binary_runtime_size >= ULONG_MAX - PAGE_SIZE)
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index b6d10dceb669..50519ed837d4 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -26,6 +26,7 @@
static struct tpm_digest *digests;
LIST_HEAD(ima_measurements); /* list of all measurements */
+LIST_HEAD(ima_measurements_staged); /* list of staged measurements */
#ifdef CONFIG_IMA_KEXEC
static unsigned long binary_runtime_size[BINARY__LAST];
#else
@@ -45,11 +46,11 @@ atomic_long_t ima_num_violations = ATOMIC_LONG_INIT(0);
/* key: inode (before secure-hashing a file) */
struct hlist_head __rcu *ima_htable;
-/* mutex protects atomicity of extending measurement list
+/* mutex protects atomicity of extending and staging measurement list
* and extending the TPM PCR aggregate. Since tpm_extend can take
* long (and the tpm driver uses a mutex), we can't use the spinlock.
*/
-static DEFINE_MUTEX(ima_extend_list_mutex);
+DEFINE_MUTEX(ima_extend_list_mutex);
/*
* Used internally by the kernel to suspend measurements.
@@ -174,12 +175,16 @@ static int ima_add_digest_entry(struct ima_template_entry *entry,
lockdep_is_held(&ima_extend_list_mutex));
atomic_long_inc(&ima_num_entries[BINARY]);
+ atomic_long_inc(&ima_num_entries[BINARY_FULL]);
+
if (update_htable) {
key = ima_hash_key(entry->digests[ima_hash_algo_idx].digest);
hlist_add_head_rcu(&qe->hnext, &htable[key]);
}
ima_update_binary_runtime_size(entry, BINARY);
+ ima_update_binary_runtime_size(entry, BINARY_FULL);
+
return 0;
}
@@ -280,6 +285,94 @@ int ima_add_template_entry(struct ima_template_entry *entry, int violation,
return result;
}
+int ima_queue_stage(void)
+{
+ int ret = 0;
+
+ mutex_lock(&ima_extend_list_mutex);
+ if (!list_empty(&ima_measurements_staged)) {
+ ret = -EEXIST;
+ goto out_unlock;
+ }
+
+ if (list_empty(&ima_measurements)) {
+ ret = -ENOENT;
+ goto out_unlock;
+ }
+
+ list_replace(&ima_measurements, &ima_measurements_staged);
+ INIT_LIST_HEAD(&ima_measurements);
+
+ atomic_long_set(&ima_num_entries[BINARY_STAGED],
+ atomic_long_read(&ima_num_entries[BINARY]));
+ atomic_long_set(&ima_num_entries[BINARY], 0);
+
+ if (IS_ENABLED(CONFIG_IMA_KEXEC)) {
+ binary_runtime_size[BINARY_STAGED] =
+ binary_runtime_size[BINARY];
+ binary_runtime_size[BINARY] = 0;
+ }
+out_unlock:
+ mutex_unlock(&ima_extend_list_mutex);
+ return ret;
+}
+
+static void ima_queue_delete(struct list_head *head);
+
+int ima_queue_staged_delete_all(void)
+{
+ LIST_HEAD(ima_measurements_trim);
+
+ mutex_lock(&ima_extend_list_mutex);
+ if (list_empty(&ima_measurements_staged)) {
+ mutex_unlock(&ima_extend_list_mutex);
+ return -ENOENT;
+ }
+
+ list_replace(&ima_measurements_staged, &ima_measurements_trim);
+ INIT_LIST_HEAD(&ima_measurements_staged);
+
+ atomic_long_set(&ima_num_entries[BINARY_STAGED], 0);
+
+ if (IS_ENABLED(CONFIG_IMA_KEXEC))
+ binary_runtime_size[BINARY_STAGED] = 0;
+
+ mutex_unlock(&ima_extend_list_mutex);
+
+ ima_queue_delete(&ima_measurements_trim);
+ return 0;
+}
+
+static void ima_queue_delete(struct list_head *head)
+{
+ struct ima_queue_entry *qe, *qe_tmp;
+ unsigned int i;
+
+ list_for_each_entry_safe(qe, qe_tmp, head, later) {
+ /*
+ * Safe to free template_data here without synchronize_rcu()
+ * because the only htable reader, ima_lookup_digest_entry(),
+ * accesses only entry->digests, not template_data. If new
+ * htable readers are added that access template_data, a
+ * synchronize_rcu() is required here.
+ */
+ for (i = 0; i < qe->entry->template_desc->num_fields; i++) {
+ kfree(qe->entry->template_data[i].data);
+ qe->entry->template_data[i].data = NULL;
+ qe->entry->template_data[i].len = 0;
+ }
+
+ list_del(&qe->later);
+
+ /* No leak if condition is false, referenced by ima_htable. */
+ if (IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE)) {
+ kfree(qe->entry->digests);
+ kfree(qe->entry);
+ kfree(qe);
+ }
+ }
+}
+
int ima_restore_measurement_entry(struct ima_template_entry *entry)
{
int result = 0;
--
2.43.0
^ permalink raw reply related
* [PATCH v5 08/13] ima: Introduce ima_dump_measurement()
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Introduce ima_dump_measurement() to simplify the code of
ima_dump_measurement_list() and to avoid repeating the
ima_dump_measurement() code block if iteration occurs on multiple lists.
No functional change: only code moved to a separate function.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima_kexec.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 44ebefbdcab0..d7d0fb639d99 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -80,6 +80,17 @@ static int ima_alloc_kexec_file_buf(size_t segment_size)
return 0;
}
+static int ima_dump_measurement(struct ima_kexec_hdr *khdr,
+ struct ima_queue_entry *qe)
+{
+ if (ima_kexec_file.count >= ima_kexec_file.size)
+ return -EINVAL;
+
+ khdr->count++;
+ ima_measurements_show(&ima_kexec_file, qe);
+ return 0;
+}
+
static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
unsigned long segment_size)
{
@@ -97,13 +108,9 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
khdr.version = 1;
/* This is an append-only list, no need to hold the RCU read lock */
list_for_each_entry_rcu(qe, &ima_measurements, later, true) {
- if (ima_kexec_file.count < ima_kexec_file.size) {
- khdr.count++;
- ima_measurements_show(&ima_kexec_file, qe);
- } else {
- ret = -EINVAL;
+ ret = ima_dump_measurement(&khdr, qe);
+ if (ret < 0)
break;
- }
}
/*
--
2.43.0
^ permalink raw reply related
* [PATCH v5 07/13] ima: Use snprintf() in create_securityfs_measurement_lists
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Use the more secure snprintf() function (accepting the buffer size) in
create_securityfs_measurement_lists().
No functional change: sprintf() and snprintf() have the same behavior.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima_fs.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 68edea7139d5..7709a4576322 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -472,11 +472,13 @@ static int __init create_securityfs_measurement_lists(void)
struct dentry *dentry;
if (algo == HASH_ALGO__LAST)
- sprintf(file_name, "ascii_runtime_measurements_tpm_alg_%x",
- ima_tpm_chip->allocated_banks[i].alg_id);
+ snprintf(file_name, sizeof(file_name),
+ "ascii_runtime_measurements_tpm_alg_%x",
+ ima_tpm_chip->allocated_banks[i].alg_id);
else
- sprintf(file_name, "ascii_runtime_measurements_%s",
- hash_algo_name[algo]);
+ snprintf(file_name, sizeof(file_name),
+ "ascii_runtime_measurements_%s",
+ hash_algo_name[algo]);
dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
ima_dir, (void *)(uintptr_t)i,
&ima_ascii_measurements_ops);
@@ -484,11 +486,13 @@ static int __init create_securityfs_measurement_lists(void)
return PTR_ERR(dentry);
if (algo == HASH_ALGO__LAST)
- sprintf(file_name, "binary_runtime_measurements_tpm_alg_%x",
- ima_tpm_chip->allocated_banks[i].alg_id);
+ snprintf(file_name, sizeof(file_name),
+ "binary_runtime_measurements_tpm_alg_%x",
+ ima_tpm_chip->allocated_banks[i].alg_id);
else
- sprintf(file_name, "binary_runtime_measurements_%s",
- hash_algo_name[algo]);
+ snprintf(file_name, sizeof(file_name),
+ "binary_runtime_measurements_%s",
+ hash_algo_name[algo]);
dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
ima_dir, (void *)(uintptr_t)i,
&ima_measurements_ops);
--
2.43.0
^ permalink raw reply related
* [PATCH v5 06/13] ima: Mediate open/release method of the measurements list
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Introduce the ima_measure_users counter, to implement a semaphore-like
locking scheme where the binary and ASCII measurements list interfaces can
be concurrently open by multiple readers, or alternatively by a single
writer.
A semaphore cannot be used because the kernel cannot return to user space
with a lock held.
Introduce the ima_measure_lock() and ima_measure_unlock() primitives, to
respectively lock/unlock the interfaces (safely with the ima_measure_users
counter, without holding a lock).
Finally, introduce _ima_measurements_open() to lock the interface before
seq_open(), and call it from ima_measurements_open() and
ima_ascii_measurements_open(). And, introduce ima_measurements_release(),
to unlock the interface.
Require CAP_SYS_ADMIN if the interface is opened for write (not possible
for the current measurements interfaces, since they only have read
permission).
No functional changes: multiple readers are allowed as before.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima_fs.c | 71 +++++++++++++++++++++++++++++++--
1 file changed, 67 insertions(+), 4 deletions(-)
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 9a8dba14d82a..68edea7139d5 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -25,6 +25,8 @@
#include "ima.h"
static DEFINE_MUTEX(ima_write_mutex);
+static DEFINE_MUTEX(ima_measure_mutex);
+static long ima_measure_users;
bool ima_canonical_fmt;
static int __init default_canonical_fmt_setup(char *str)
@@ -209,16 +211,76 @@ static const struct seq_operations ima_measurments_seqops = {
.show = ima_measurements_show
};
+static int ima_measure_lock(bool write)
+{
+ mutex_lock(&ima_measure_mutex);
+ if ((write && ima_measure_users != 0) ||
+ (!write && ima_measure_users < 0)) {
+ mutex_unlock(&ima_measure_mutex);
+ return -EBUSY;
+ }
+
+ if (write)
+ ima_measure_users--;
+ else
+ ima_measure_users++;
+ mutex_unlock(&ima_measure_mutex);
+ return 0;
+}
+
+static void ima_measure_unlock(bool write)
+{
+ mutex_lock(&ima_measure_mutex);
+ if (write)
+ ima_measure_users++;
+ else
+ ima_measure_users--;
+ mutex_unlock(&ima_measure_mutex);
+}
+
+static int _ima_measurements_open(struct inode *inode, struct file *file,
+ const struct seq_operations *seq_ops)
+{
+ bool write = (file->f_mode & FMODE_WRITE);
+ int ret;
+
+ if (write && !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ ret = ima_measure_lock(write);
+ if (ret < 0)
+ return ret;
+
+ ret = seq_open(file, seq_ops);
+ if (ret < 0)
+ ima_measure_unlock(write);
+
+ return ret;
+}
+
static int ima_measurements_open(struct inode *inode, struct file *file)
{
- return seq_open(file, &ima_measurments_seqops);
+ return _ima_measurements_open(inode, file, &ima_measurments_seqops);
+}
+
+static int ima_measurements_release(struct inode *inode, struct file *file)
+{
+ bool write = (file->f_mode & FMODE_WRITE);
+ int ret;
+
+ /* seq_release() always returns zero. */
+ ret = seq_release(inode, file);
+
+ ima_measure_unlock(write);
+
+ return ret;
}
static const struct file_operations ima_measurements_ops = {
.open = ima_measurements_open,
.read = seq_read,
.llseek = seq_lseek,
- .release = seq_release,
+ .release = ima_measurements_release,
};
void ima_print_digest(struct seq_file *m, u8 *digest, u32 size)
@@ -283,14 +345,15 @@ static const struct seq_operations ima_ascii_measurements_seqops = {
static int ima_ascii_measurements_open(struct inode *inode, struct file *file)
{
- return seq_open(file, &ima_ascii_measurements_seqops);
+ return _ima_measurements_open(inode, file,
+ &ima_ascii_measurements_seqops);
}
static const struct file_operations ima_ascii_measurements_ops = {
.open = ima_ascii_measurements_open,
.read = seq_read,
.llseek = seq_lseek,
- .release = seq_release,
+ .release = ima_measurements_release,
};
static ssize_t ima_read_policy(char *path)
--
2.43.0
^ permalink raw reply related
* [PATCH v5 05/13] ima: Introduce _ima_measurements_start() and _ima_measurements_next()
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Introduce _ima_measurements_start() and _ima_measurements_next(), renamed
from ima_measurements_start() and ima_measurements_next(), to include the
list head as an additional parameter, so that iteration on different lists
can be implemented by calling those functions.
No functional change: ima_measurements_start() and ima_measurements_next()
pass the ima_measurements list head, used before.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima_fs.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 79b0f287c668..9a8dba14d82a 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -72,14 +72,15 @@ static const struct file_operations ima_measurements_count_ops = {
};
/* returns pointer to hlist_node */
-static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
+static void *_ima_measurements_start(struct seq_file *m, loff_t *pos,
+ struct list_head *head)
{
loff_t l = *pos;
struct ima_queue_entry *qe;
/* we need a lock since pos could point beyond last element */
rcu_read_lock();
- list_for_each_entry_rcu(qe, &ima_measurements, later) {
+ list_for_each_entry_rcu(qe, head, later) {
if (!l--) {
rcu_read_unlock();
return qe;
@@ -89,7 +90,13 @@ static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
return NULL;
}
-static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
+static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
+{
+ return _ima_measurements_start(m, pos, &ima_measurements);
+}
+
+static void *_ima_measurements_next(struct seq_file *m, void *v, loff_t *pos,
+ struct list_head *head)
{
struct ima_queue_entry *qe = v;
@@ -101,7 +108,12 @@ static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
rcu_read_unlock();
(*pos)++;
- return (&qe->later == &ima_measurements) ? NULL : qe;
+ return (&qe->later == head) ? NULL : qe;
+}
+
+static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ return _ima_measurements_next(m, v, pos, &ima_measurements);
}
static void ima_measurements_stop(struct seq_file *m, void *v)
--
2.43.0
^ permalink raw reply related
* [PATCH v5 04/13] ima: Introduce per binary measurements list type binary_runtime_size value
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Make binary_runtime_size as an array, to have separate counters per binary
measurements list type. Currently, define the BINARY type for the existing
binary measurements list.
Introduce ima_update_binary_runtime_size() to facilitate updating a
binary_runtime_size value with a given binary measurement list type.
Also add the binary measurements list type parameter to
ima_get_binary_runtime_size(), to retrieve the desired value. Retrieving
the value is now done under the ima_extend_list_mutex, since there can be
concurrent updates.
No functional change (except for the mutex usage, that fixes the
concurrency issue): the BINARY array element is equivalent to the old
binary_runtime_size.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima.h | 2 +-
security/integrity/ima/ima_kexec.c | 5 ++--
security/integrity/ima/ima_queue.c | 40 +++++++++++++++++++++---------
3 files changed, 32 insertions(+), 15 deletions(-)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index b417c9d792d8..f8ab6b604c0d 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -319,7 +319,7 @@ int ima_restore_measurement_entry(struct ima_template_entry *entry);
int ima_restore_measurement_list(loff_t bufsize, void *buf);
int ima_measurements_show(struct seq_file *m, void *v);
int __init ima_init_htable(void);
-unsigned long ima_get_binary_runtime_size(void);
+unsigned long ima_get_binary_runtime_size(enum binary_lists binary_list);
int ima_init_template(void);
void ima_init_template_list(void);
int __init ima_init_digests(void);
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 40962dc0ca86..44ebefbdcab0 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -42,7 +42,7 @@ void ima_measure_kexec_event(const char *event_name)
long len;
int n;
- buf_size = ima_get_binary_runtime_size();
+ buf_size = ima_get_binary_runtime_size(BINARY);
len = atomic_long_read(&ima_num_entries[BINARY]);
n = scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN,
@@ -159,7 +159,8 @@ void ima_add_kexec_buffer(struct kimage *image)
else
extra_memory = CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB * 1024;
- binary_runtime_size = ima_get_binary_runtime_size() + extra_memory;
+ binary_runtime_size = ima_get_binary_runtime_size(BINARY) +
+ extra_memory;
if (binary_runtime_size >= ULONG_MAX - PAGE_SIZE)
kexec_segment_size = ULONG_MAX;
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 952172a4905d..b6d10dceb669 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -27,9 +27,11 @@ static struct tpm_digest *digests;
LIST_HEAD(ima_measurements); /* list of all measurements */
#ifdef CONFIG_IMA_KEXEC
-static unsigned long binary_runtime_size;
+static unsigned long binary_runtime_size[BINARY__LAST];
#else
-static unsigned long binary_runtime_size = ULONG_MAX;
+static unsigned long binary_runtime_size[BINARY__LAST] = {
+ [0 ... BINARY__LAST - 1] = ULONG_MAX
+};
#endif
/* num of stored measurements in the list */
@@ -131,6 +133,20 @@ static int get_binary_runtime_size(struct ima_template_entry *entry)
return size;
}
+static void ima_update_binary_runtime_size(struct ima_template_entry *entry,
+ enum binary_lists binary_list)
+{
+ int size;
+
+ if (binary_runtime_size[binary_list] == ULONG_MAX)
+ return;
+
+ size = get_binary_runtime_size(entry);
+ binary_runtime_size[binary_list] =
+ (binary_runtime_size[binary_list] < ULONG_MAX - size) ?
+ binary_runtime_size[binary_list] + size : ULONG_MAX;
+}
+
/* ima_add_template_entry helper function:
* - Add template entry to the measurement list and hash table, for
* all entries except those carried across kexec.
@@ -163,13 +179,7 @@ static int ima_add_digest_entry(struct ima_template_entry *entry,
hlist_add_head_rcu(&qe->hnext, &htable[key]);
}
- if (binary_runtime_size != ULONG_MAX) {
- int size;
-
- size = get_binary_runtime_size(entry);
- binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ?
- binary_runtime_size + size : ULONG_MAX;
- }
+ ima_update_binary_runtime_size(entry, BINARY);
return 0;
}
@@ -178,12 +188,18 @@ static int ima_add_digest_entry(struct ima_template_entry *entry,
* entire binary_runtime_measurement list, including the ima_kexec_hdr
* structure.
*/
-unsigned long ima_get_binary_runtime_size(void)
+unsigned long ima_get_binary_runtime_size(enum binary_lists binary_list)
{
- if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
+ unsigned long val;
+
+ mutex_lock(&ima_extend_list_mutex);
+ val = binary_runtime_size[binary_list];
+ mutex_unlock(&ima_extend_list_mutex);
+
+ if (val >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
return ULONG_MAX;
else
- return binary_runtime_size + sizeof(struct ima_kexec_hdr);
+ return val + sizeof(struct ima_kexec_hdr);
}
static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr)
--
2.43.0
^ permalink raw reply related
* [PATCH v5 03/13] ima: Introduce per binary measurements list type ima_num_entries counter
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Make ima_num_entries as an array, to have separate counters per binary
measurements list type. Currently, define the BINARY type for the existing
binary measurements list.
No functional change: the BINARY type is equivalent to the value without
the array.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima.h | 9 ++++++++-
security/integrity/ima/ima_fs.c | 3 +--
security/integrity/ima/ima_kexec.c | 2 +-
security/integrity/ima/ima_queue.c | 7 +++++--
4 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 94bf890628e5..b417c9d792d8 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -28,6 +28,13 @@ enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_BINARY_NO_FIELD_LEN,
IMA_SHOW_BINARY_OLD_STRING_FMT, IMA_SHOW_ASCII };
enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8, TPM_PCR10 = 10 };
+/*
+ * BINARY: current binary measurements list
+ */
+enum binary_lists {
+ BINARY, BINARY__LAST
+};
+
/* digest size for IMA, fits SHA1 or MD5 */
#define IMA_DIGEST_SIZE SHA1_DIGEST_SIZE
#define IMA_EVENT_NAME_LEN_MAX 255
@@ -325,7 +332,7 @@ int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
*/
extern spinlock_t ima_queue_lock;
-extern atomic_long_t ima_num_entries;
+extern atomic_long_t ima_num_entries[BINARY__LAST];
extern atomic_long_t ima_num_violations;
extern struct hlist_head __rcu *ima_htable;
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index aaa460d70ff7..79b0f287c668 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -63,8 +63,7 @@ static ssize_t ima_show_measurements_count(struct file *filp,
char __user *buf,
size_t count, loff_t *ppos)
{
- return ima_show_counter(buf, count, ppos, &ima_num_entries);
-
+ return ima_show_counter(buf, count, ppos, &ima_num_entries[BINARY]);
}
static const struct file_operations ima_measurements_count_ops = {
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 5801649fbbef..40962dc0ca86 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -43,7 +43,7 @@ void ima_measure_kexec_event(const char *event_name)
int n;
buf_size = ima_get_binary_runtime_size();
- len = atomic_long_read(&ima_num_entries);
+ len = atomic_long_read(&ima_num_entries[BINARY]);
n = scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN,
"kexec_segment_size=%lu;ima_binary_runtime_size=%lu;"
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 41f4941ceaad..952172a4905d 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -33,7 +33,10 @@ static unsigned long binary_runtime_size = ULONG_MAX;
#endif
/* num of stored measurements in the list */
-atomic_long_t ima_num_entries = ATOMIC_LONG_INIT(0);
+atomic_long_t ima_num_entries[BINARY__LAST] = {
+ [0 ... BINARY__LAST - 1] = ATOMIC_LONG_INIT(0)
+};
+
/* num of violations in the list */
atomic_long_t ima_num_violations = ATOMIC_LONG_INIT(0);
@@ -154,7 +157,7 @@ static int ima_add_digest_entry(struct ima_template_entry *entry,
htable = rcu_dereference_protected(ima_htable,
lockdep_is_held(&ima_extend_list_mutex));
- atomic_long_inc(&ima_num_entries);
+ atomic_long_inc(&ima_num_entries[BINARY]);
if (update_htable) {
key = ima_hash_key(entry->digests[ima_hash_algo_idx].digest);
hlist_add_head_rcu(&qe->hnext, &htable[key]);
--
2.43.0
^ permalink raw reply related
* [PATCH v5 02/13] ima: Replace static htable queue with dynamically allocated array
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
In-Reply-To: <20260429160319.4162918-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
The IMA hash table is a fixed-size array of hlist_head buckets:
struct hlist_head ima_htable[IMA_MEASURE_HTABLE_SIZE];
IMA_MEASURE_HTABLE_SIZE is (1 << IMA_HASH_BITS) = 1024 buckets, each a
struct hlist_head (one pointer, 8 bytes on 64-bit). That is 8 KiB allocated
in BSS for every kernel, regardless of whether IMA is ever used, and
regardless of how many measurements are actually made.
Replace the fixed-size array with a RCU-protected pointer to a dynamically
allocated array that is initialized in ima_init_htable(), which is called
from ima_init() during early boot. ima_init_htable() calls the static
function ima_alloc_replace_htable() which, other than initializing the hash
table the first time, can also hot-swap the existing hash table with a
blank one.
The allocation in ima_alloc_replace_htable() uses kcalloc() so the buckets
are zero-initialised (equivalent to HLIST_HEAD_INIT { .first = NULL }).
Callers of ima_alloc_replace_htable() must call synchronize_rcu() and free
the returned hash table.
Finally, access the hash table with rcu_dereference() in
ima_lookup_digest_entry() (reader side) and with
rcu_dereference_protected() in ima_add_digest_entry() (writer side).
No functional change: bucket count, hash function, and all locking remain
identical.
Link: https://github.com/linux-integrity/linux/issues/1
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima.h | 3 +-
security/integrity/ima/ima_init.c | 5 ++++
security/integrity/ima/ima_queue.c | 48 ++++++++++++++++++++++++++----
3 files changed, 50 insertions(+), 6 deletions(-)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 51a8a582df56..94bf890628e5 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -311,6 +311,7 @@ bool ima_template_has_modsig(const struct ima_template_desc *ima_template);
int ima_restore_measurement_entry(struct ima_template_entry *entry);
int ima_restore_measurement_list(loff_t bufsize, void *buf);
int ima_measurements_show(struct seq_file *m, void *v);
+int __init ima_init_htable(void);
unsigned long ima_get_binary_runtime_size(void);
int ima_init_template(void);
void ima_init_template_list(void);
@@ -326,7 +327,7 @@ extern spinlock_t ima_queue_lock;
extern atomic_long_t ima_num_entries;
extern atomic_long_t ima_num_violations;
-extern struct hlist_head ima_htable[IMA_MEASURE_HTABLE_SIZE];
+extern struct hlist_head __rcu *ima_htable;
static inline unsigned int ima_hash_key(u8 *digest)
{
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index a2f34f2d8ad7..7e0aa09a12e6 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -140,6 +140,11 @@ int __init ima_init(void)
rc = ima_init_digests();
if (rc != 0)
return rc;
+
+ rc = ima_init_htable();
+ if (rc != 0)
+ return rc;
+
rc = ima_add_boot_aggregate(); /* boot aggregate must be first entry */
if (rc != 0)
return rc;
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 1f6515f7d015..41f4941ceaad 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -38,9 +38,7 @@ atomic_long_t ima_num_entries = ATOMIC_LONG_INIT(0);
atomic_long_t ima_num_violations = ATOMIC_LONG_INIT(0);
/* key: inode (before secure-hashing a file) */
-struct hlist_head ima_htable[IMA_MEASURE_HTABLE_SIZE] = {
- [0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
-};
+struct hlist_head __rcu *ima_htable;
/* mutex protects atomicity of extending measurement list
* and extending the TPM PCR aggregate. Since tpm_extend can take
@@ -54,17 +52,53 @@ static DEFINE_MUTEX(ima_extend_list_mutex);
*/
static bool ima_measurements_suspended;
+/* Callers must call synchronize_rcu() and free the hash table. */
+static struct hlist_head *ima_alloc_replace_htable(void)
+{
+ struct hlist_head *old_htable, *new_htable;
+
+ /* Initializing to zeros is equivalent to call HLIST_HEAD_INIT. */
+ new_htable = kcalloc(IMA_MEASURE_HTABLE_SIZE, sizeof(struct hlist_head),
+ GFP_KERNEL);
+ if (!new_htable)
+ return ERR_PTR(-ENOMEM);
+
+ old_htable = rcu_replace_pointer(ima_htable, new_htable,
+ lockdep_is_held(&ima_extend_list_mutex));
+
+ return old_htable;
+}
+
+int __init ima_init_htable(void)
+{
+ struct hlist_head *old_htable;
+
+ mutex_lock(&ima_extend_list_mutex);
+ old_htable = ima_alloc_replace_htable();
+ mutex_unlock(&ima_extend_list_mutex);
+
+ if (IS_ERR(old_htable))
+ return PTR_ERR(old_htable);
+
+ /* Synchronize_rcu() and kfree() not necessary, only for robustness. */
+ synchronize_rcu();
+ kfree(old_htable);
+ return 0;
+}
+
/* lookup up the digest value in the hash table, and return the entry */
static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
int pcr)
{
struct ima_queue_entry *qe, *ret = NULL;
+ struct hlist_head *htable;
unsigned int key;
int rc;
key = ima_hash_key(digest_value);
rcu_read_lock();
- hlist_for_each_entry_rcu(qe, &ima_htable[key], hnext) {
+ htable = rcu_dereference(ima_htable);
+ hlist_for_each_entry_rcu(qe, &htable[key], hnext) {
rc = memcmp(qe->entry->digests[ima_hash_algo_idx].digest,
digest_value, hash_digest_size[ima_hash_algo]);
if ((rc == 0) && (qe->entry->pcr == pcr)) {
@@ -104,6 +138,7 @@ static int ima_add_digest_entry(struct ima_template_entry *entry,
bool update_htable)
{
struct ima_queue_entry *qe;
+ struct hlist_head *htable;
unsigned int key;
qe = kmalloc_obj(*qe);
@@ -116,10 +151,13 @@ static int ima_add_digest_entry(struct ima_template_entry *entry,
INIT_LIST_HEAD(&qe->later);
list_add_tail_rcu(&qe->later, &ima_measurements);
+ htable = rcu_dereference_protected(ima_htable,
+ lockdep_is_held(&ima_extend_list_mutex));
+
atomic_long_inc(&ima_num_entries);
if (update_htable) {
key = ima_hash_key(entry->digests[ima_hash_algo_idx].digest);
- hlist_add_head_rcu(&qe->hnext, &ima_htable[key]);
+ hlist_add_head_rcu(&qe->hnext, &htable[key]);
}
if (binary_runtime_size != ULONG_MAX) {
--
2.43.0
^ permalink raw reply related
* [PATCH v5 00/13] ima: Introduce staging mechanism
From: Roberto Sassu @ 2026-04-29 16:03 UTC (permalink / raw)
To: corbet, skhan, zohar, dmitry.kasatkin, eric.snowberg, paul,
jmorris, serge
Cc: linux-doc, linux-kernel, linux-integrity, linux-security-module,
gregorylumen, chenste, nramas, Roberto Sassu
From: Roberto Sassu <roberto.sassu@huawei.com>
Introduction
============
The IMA measurements list is currently stored in the kernel memory.
Memory occupation grows linearly with the number of entries, and can
become a problem especially in environments with reduced resources.
While there is an advantage in keeping the IMA measurements list in
kernel memory, so that it is always available for reading from the
securityfs interfaces, storing it elsewhere would make it possible to
free precious memory for other kernel components.
Storing the IMA measurements list outside the kernel does not introduce
security issues, since its integrity is anyway protected by the TPM.
Hence, the new IMA staging mechanism is introduced to allow user space
to remove the desired portion of the measurements list from the kernel.
Usage
=====
The IMA staging mechanism can be enabled from the kernel configuration
with the CONFIG_IMA_STAGING option.
If it is enabled, IMA duplicates the current measurements interfaces
(both binary and ASCII), by adding the _staged file suffix. Both the
original and the staging interfaces gain the write permission for the
root user and group, but require the process to have CAP_SYS_ADMIN set.
The staging mechanism supports two flavors.
Staging with prompt
~~~~~~~~~~~~~~~~~~~
The current measurements list is moved to a temporary staging area, and
staged measurements are deleted upon confirmation.
This staging process is achieved with the following steps.
1. echo A > <original interface>: the user requests IMA to stage the
entire measurements list;
2. cat <_staged interface>: the user reads the staged measurements;
3. echo D > <_staged interface>: the user requests IMA to delete
staged measurements.
Staging and deleting
~~~~~~~~~~~~~~~~~~~~
N measurements are staged to a temporary staging area, and immediately
deleted without further confirmation.
This staging process is achieved with the following steps.
1. cat <original interface>: the user reads the current measurements
list and determines what the value N for staging should be;
2. echo N > <original interface>: the user requests IMA to delete N
measurements from the current measurements list.
Management of Staged Measurements
=================================
Since with the staging mechanism measurement entries are removed from
the kernel, the user needs to save the staged ones in a storage and
concatenate them together, so that it can present them to remote
attestation agents as if staging was never done.
Patch set content
=================
Patches 1-8 are preparatory patches to quickly replace the hash table,
maintain separate counters for the different measurements list types,
mediate access to the measurements list interface, and simplify the staging
patches.
Patch 9 introduces the staging with prompt flavor. Patch 10 makes it
possible to flush the hash table when deleting all the staged measurements.
Patch 11 introduces the staging and deleting flavor. Patch 12 avoids
measurements entries to be stored twice if there is contention between the
measurements interfaces and kexec. Patch 13 adds the documentation of the
staging mechanism.
Changelog
=========
v4:
- Add write permission to the original measurement interface, and move
the A and N staging commands to that interface
- Explain better the two staging flavors and highlight that the staging
and delete only stages measurements internally
- Rename ima_queue_staged_delete_partial() to ima_queue_delete_partial()
- Replace ima_staged_measurements_prepended with per measurements list
flag to avoid copying staged and active list measurements twice
- Optimize the staging and deleting flavor by locklessly determining the
cut position in the active list, and immediately deleting entries
without explicit staging and splicing (suggested by Steven Chen)
v3:
- Add Kconfig option to enable the staging mechanism (suggested by Mimi)
- Change the meaning of BINARY_STAGED to be just the staged measurements
- Separate the two staging flavors in two different functions:
ima_queue_staged_delete_all() for staging with prompt,
ima_queue_staged_delete_partial() for staging and deleting
- Delete N entries without staging first (suggested by Mimi)
- Avoid duplicate staged entries if there is contention between the
measurements list interfaces and kexec
v2:
- New patch to move measurements and violation counters outside the
ima_h_table structure
- New patch to quickly replace the hash table
- Forbid partial deletion when flushing hash table (suggested by Mimi)
- Ignore ima_flush_htable if CONFIG_IMA_DISABLE_HTABLE is enabled
- BINARY_SIZE_* renamed to BINARY_* for better clarity
- Removed ima_measurements_staged_exist and testing list empty instead
- ima_queue_stage_trim() and ima_queue_delete_staged_trimmed() renamed to
ima_queue_stage() and ima_queue_delete_staged()
- New delete interval [1, ULONG_MAX - 1]
- Rename ima_measure_lock to ima_measure_mutex
- Move seq_open() and seq_release() outside the ima_measure_mutex lock
- Drop ima_measurements_staged_read() and use seq_read() instead
- Optimize create_securityfs_measurement_lists() changes
- New file name format with _staged suffix at the end of the file name
- Use _rcu list variant in ima_dump_measurement_list()
- Remove support for direct trimming and splice the remaining entries to
the active list (suggested by Mimi)
- Hot swap the hash table if flushing is requested
v1:
- Support for direct trimming without staging
- Support unstaging on kexec (requested by Gregory Lumen)
Roberto Sassu (13):
ima: Remove ima_h_table structure
ima: Replace static htable queue with dynamically allocated array
ima: Introduce per binary measurements list type ima_num_entries
counter
ima: Introduce per binary measurements list type binary_runtime_size
value
ima: Introduce _ima_measurements_start() and _ima_measurements_next()
ima: Mediate open/release method of the measurements list
ima: Use snprintf() in create_securityfs_measurement_lists
ima: Introduce ima_dump_measurement()
ima: Add support for staging measurements with prompt
ima: Add support for flushing the hash table when staging measurements
ima: Support staging and deleting N measurements entries
ima: Return error on deleting measurements already copied during kexec
doc: security: Add documentation of the IMA staging mechanism
.../admin-guide/kernel-parameters.txt | 4 +
Documentation/security/IMA-staging.rst | 163 +++++++++
Documentation/security/index.rst | 1 +
MAINTAINERS | 2 +
security/integrity/ima/Kconfig | 16 +
security/integrity/ima/ima.h | 32 +-
security/integrity/ima/ima_api.c | 2 +-
security/integrity/ima/ima_fs.c | 315 ++++++++++++++++--
security/integrity/ima/ima_init.c | 5 +
security/integrity/ima/ima_kexec.c | 53 ++-
security/integrity/ima/ima_queue.c | 283 ++++++++++++++--
11 files changed, 803 insertions(+), 73 deletions(-)
create mode 100644 Documentation/security/IMA-staging.rst
--
2.43.0
^ permalink raw reply
* Re: [RFC PATCH v2 1/4] security: ima: call ima_init() again at late_initcall_sync for defered TPM
From: Roberto Sassu @ 2026-04-29 13:33 UTC (permalink / raw)
To: Paul Moore, Mimi Zohar
Cc: Yeoreum Yun, roberto.sassu, Jonathan McDowell,
linux-security-module, linux-kernel, linux-integrity,
linux-arm-kernel, kvmarm, jmorris, serge, dmitry.kasatkin,
eric.snowberg, jarkko, jgg, sudeep.holla, maz, oupton, joey.gouly,
suzuki.poulose, yuzenghui, catalin.marinas, will, noodles,
sebastianene
In-Reply-To: <CAHC9VhS_WgwhW_NDO91LoTeSzdieGqbwqnwPq8KpavH1_Lwi7g@mail.gmail.com>
On Mon, 2026-04-27 at 21:31 -0400, Paul Moore wrote:
> On Fri, Apr 24, 2026 at 6:49 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> > On Fri, 2026-04-24 at 18:10 -0400, Paul Moore wrote:
> > > (I'm assuming you meant initcall and not syscall above, but if you're
> > > talking about something else, please let me know.)
> > >
> > > Saying that you aren't comfortable moving IMA initialization to
> > > late-sync is inconsistent with allowing IMA initialization to be
> > > deferred to late-sync. Either it is okay to initialize IMA in
> > > late-sync or it isn't. You must pick one.
> >
> > Yes, we're discussing late_initcall and late_initcall_sync.
> >
> > I prefer to look at it as being pragmatic. I'd rather err on the side of caution
> > and not move the syscall to late_initcall_sync, than move it.
>
> If you were truly erring on the side of caution you wouldn't allow
> late-sync initialization without knowing if it was safe or not.
> Determine whether IMA initialization is safe at late-sync. If it is
> safe, move the init to late-sync; if not, keep it at late and figure
> out another mechanism to sync with the TPM availability. If needed,
> you could probably use the LSM notifier to enable the TPM driver to
> signal when it is up and running.
Yes, I agree with you, or transition or not.
However, all of this looks very fragile and easy to be broken. If we
want to be on the safe side, we can use any notification mechanism that
is suitable, but at the same time from IMA side we need to deny any
file access that would require a measurement until the TPM comes up.
If you accept this, I don't have any problem to move to late_sync.
Roberto
^ permalink raw reply
* [linus:master] [proc] 599bbba5a3: kernel-selftests.mm.ksft_mkdirty.sh.mkdirty.fail
From: kernel test robot @ 2026-04-29 8:26 UTC (permalink / raw)
To: Linus Torvalds, Mark Brown
Cc: oe-lkp, lkp, linux-kernel, Vova Tokarev, linux-security-module,
oliver.sang
Hello,
by this commit, we noticed the expected config diff:
==================== PARENT FIRST_BAD KCONFIGS fdcbb1bc06508eb7ad961b3876b16382ae678ef8 ====================
--- /pkg/linux/x86_64-rhel-9.4-kselftests/gcc-14/fdcbb1bc06508eb7ad961b3876b16382ae678ef8/.config 2026-04-26 22:54:11.801204874 +0200
+++ /pkg/linux/x86_64-rhel-9.4-kselftests/gcc-14/599bbba5a36f6de57ab14c373c25881e2b5273f5/.config 2026-04-26 22:01:12.692502621 +0200
@@ -8959,8 +8959,8 @@ CONFIG_ENCRYPTED_KEYS=y
CONFIG_KEY_DH_OPERATIONS=y
CONFIG_KEY_NOTIFICATIONS=y
# CONFIG_SECURITY_DMESG_RESTRICT is not set
-CONFIG_PROC_MEM_ALWAYS_FORCE=y
-# CONFIG_PROC_MEM_FORCE_PTRACE is not set
+# CONFIG_PROC_MEM_ALWAYS_FORCE is not set
+CONFIG_PROC_MEM_FORCE_PTRACE=y
# CONFIG_PROC_MEM_NO_FORCE is not set
CONFIG_SECURITY=y
CONFIG_HAS_SECURITY_AUDIT=y
then we saw below two cases failed upon this commit:
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/group/sc_nr_hugepages:
igk-rpl-d03/kernel-selftests/debian-13-x86_64-20250902.cgz/x86_64-rhel-9.4-kselftests/gcc-14/mm/2
fdcbb1bc06508eb7 599bbba5a36f6de57ab14c373c2
---------------- ---------------------------
fail:runs %reproduction fail:runs
| | |
:9 67% 6:6 kernel-selftests.mm.ksft_ksm.sh.fail
:9 67% 6:6 kernel-selftests.mm.ksft_mkdirty.sh.fail
we also noticed there is a fix commit in linux-next/master now, but we still
saw same failures in our tests if directly test upon it.
below full report FYI.
kernel test robot noticed "kernel-selftests.mm.ksft_mkdirty.sh.mkdirty.fail" on:
commit: 599bbba5a36f6de57ab14c373c25881e2b5273f5 ("proc: make PROC_MEM_FORCE_PTRACE the Kconfig default")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
[test failed on linus/master 254f49634ee16a731174d2ae34bc50bd5f45e731]
[test failed on linux-next/master 7080e32d3f09d8688c4a87d81bdcc71f7f606b16]
[test failed on fix commit a3907a3169d09ebaeef9631ab6a4534314545ef7]
in testcase: kernel-selftests
version: kernel-selftests-x86_64-9f2693489ef8-1_20260201
with following parameters:
group: mm
sc_nr_hugepages: 2
config: x86_64-rhel-9.4-kselftests
compiler: gcc-14
test machine: 16 threads Intel(R) Core(TM) i7-13620H (Raptor Lake) with 32G memory
(please refer to attached dmesg/kmsg for entire log/backtrace)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202604290921.ac2bf5ff-lkp@intel.com
below is from commit 599bbba5a3:
# timeout set to 900
# selftests: mm: ksft_ksm.sh
# TAP version 13
# # -----------------------------
# # running ./ksm_tests -H -s 100
# # -----------------------------
# # Number of normal pages: 0
# # Number of huge pages: 50
# # Total size: 100 MiB
# # Total time: 0.196202091 s
# # Average speed: 509.679 MiB/s
# # [PASS]
# ok 1 ksm_tests -H -s 100
# # -----------------------------
# # running ./ksm_tests -P -s 100
# # -----------------------------
# # Total size: 100 MiB
# # Total time: 0.201963596 s
# # Average speed: 495.139 MiB/s
# # [PASS]
# ok 2 ksm_tests -P -s 100
# # ----------------------------
# # running ./ksm_tests -M -p 10
# # ----------------------------
# # OK
# # [PASS]
# ok 3 ksm_tests -M -p 10
# # ----------------------
# # running ./ksm_tests -U
# # ----------------------
# # OK
# # [PASS]
# ok 4 ksm_tests -U
# # ---------------------------------
# # running ./ksm_tests -Z -p 10 -z 0
# # ---------------------------------
# # OK
# # [PASS]
# ok 5 ksm_tests -Z -p 10 -z 0
# # ---------------------------------
# # running ./ksm_tests -Z -p 10 -z 1
# # ---------------------------------
# # OK
# # [PASS]
# ok 6 ksm_tests -Z -p 10 -z 1
# # ------------------------------
# # running ./ksm_functional_tests
# # ------------------------------
# # TAP version 13
# # 1..10
# # # [RUN] test_unmerge
# # ok 1 Pages were unmerged
# # # [RUN] test_unmerge_zero_pages
# # ok 2 KSM zero pages were unmerged
# # # [RUN] test_unmerge_discarded
# # ok 3 Pages were unmerged
# # # [RUN] test_unmerge_uffd_wp
# # ok 4 Pages were unmerged
# # # [RUN] test_prot_none
# # not ok 5 ptrace write failed
# # # [RUN] test_prctl
# # ok 6 Setting/clearing PR_SET_MEMORY_MERGE works
# # # [RUN] test_prctl_fork
# # ok 7 PR_SET_MEMORY_MERGE value is inherited
# # # [RUN] test_prctl_fork_exec
# # ok 8 PR_SET_MEMORY_MERGE value is inherited
# # # [RUN] test_prctl_unmerge
# # ok 9 Pages were unmerged
# # # [RUN] test_fork_ksm_merging_page_count
# # ok 10 ksm_merging_pages is not inherited after fork
# # Bail out! 1 out of 10 tests failed
# # # Totals: pass:9 fail:1 xfail:0 xpass:0 skip:0 error:0
# # [FAIL]
# not ok 7 ksm_functional_tests # exit=1
# hwpoison_inject
# # SUMMARY: PASS=6 SKIP=0 FAIL=1
# 1..7
not ok 7 selftests: mm: ksft_ksm.sh # exit=1
...
# timeout set to 900
# selftests: mm: ksft_mkdirty.sh
# TAP version 13
# # -----------------
# # running ./mkdirty
# # -----------------
# # # [INFO] detected THP size: 2048 KiB
# # TAP version 13
# # 1..6
# # # [INFO] PTRACE write access
# # not ok 1 write() failed
# # # [INFO] PTRACE write access to THP
# # not ok 2 write() failed
# # # [INFO] Page migration
# # ok 3 SIGSEGV generated, page not modified
# # # [INFO] Page migration of THP
# # ok 4 SIGSEGV generated, page not modified
# # # [INFO] PTE-mapping a THP
# # ok 5 SIGSEGV generated, page not modified
# # # [INFO] UFFDIO_COPY
# # ok 6 SIGSEGV generated, page not modified
# # Bail out! 2 out of 6 tests failed
# # # Totals: pass:4 fail:2 xfail:0 xpass:0 skip:0 error:0
# # [FAIL]
# not ok 1 mkdirty # exit=1
# hwpoison_inject
# # SUMMARY: PASS=0 SKIP=0 FAIL=1
# 1..1
not ok 14 selftests: mm: ksft_mkdirty.sh # exit=1
below is from
[test failed on fix commit a3907a3169d09ebaeef9631ab6a4534314545ef7]
# timeout set to 900
# selftests: mm: ksft_ksm.sh
# TAP version 13
# # -----------------------------
# # running ./ksm_tests -H -s 100
# # -----------------------------
# # Number of normal pages: 0
# # Number of huge pages: 50
# # Total size: 100 MiB
# # Total time: 0.201459173 s
# # Average speed: 496.378 MiB/s
# # [PASS]
# ok 1 ksm_tests -H -s 100
# # -----------------------------
# # running ./ksm_tests -P -s 100
# # -----------------------------
# # Total size: 100 MiB
# # Total time: 0.197418993 s
# # Average speed: 506.537 MiB/s
# # [PASS]
# ok 2 ksm_tests -P -s 100
# # ----------------------------
# # running ./ksm_tests -M -p 10
# # ----------------------------
# # OK
# # [PASS]
# ok 3 ksm_tests -M -p 10
# # ----------------------
# # running ./ksm_tests -U
# # ----------------------
# # OK
# # [PASS]
# ok 4 ksm_tests -U
# # ---------------------------------
# # running ./ksm_tests -Z -p 10 -z 0
# # ---------------------------------
# # OK
# # [PASS]
# ok 5 ksm_tests -Z -p 10 -z 0
# # ---------------------------------
# # running ./ksm_tests -Z -p 10 -z 1
# # ---------------------------------
# # OK
# # [PASS]
# ok 6 ksm_tests -Z -p 10 -z 1
# # ------------------------------
# # running ./ksm_functional_tests
# # ------------------------------
# # TAP version 13
# # 1..10
# # # [RUN] test_unmerge
# # ok 1 Pages were unmerged
# # # [RUN] test_unmerge_zero_pages
# # ok 2 KSM zero pages were unmerged
# # # [RUN] test_unmerge_discarded
# # ok 3 Pages were unmerged
# # # [RUN] test_unmerge_uffd_wp
# # ok 4 Pages were unmerged
# # # [RUN] test_prot_none
# # not ok 5 ptrace write failed
# # # [RUN] test_prctl
# # ok 6 Setting/clearing PR_SET_MEMORY_MERGE works
# # # [RUN] test_prctl_fork
# # ok 7 PR_SET_MEMORY_MERGE value is inherited
# # # [RUN] test_prctl_fork_exec
# # ok 8 PR_SET_MEMORY_MERGE value is inherited
# # # [RUN] test_prctl_unmerge
# # ok 9 Pages were unmerged
# # # [RUN] test_fork_ksm_merging_page_count
# # ok 10 ksm_merging_pages is not inherited after fork
# # Bail out! 1 out of 10 tests failed
# # # Totals: pass:9 fail:1 xfail:0 xpass:0 skip:0 error:0
# # [FAIL]
# not ok 7 ksm_functional_tests # exit=1
# hwpoison_inject
# # SUMMARY: PASS=6 SKIP=0 FAIL=1
# 1..7
not ok 7 selftests: mm: ksft_ksm.sh # exit=1
...
# timeout set to 900
# selftests: mm: ksft_mkdirty.sh
# TAP version 13
# # -----------------
# # running ./mkdirty
# # -----------------
# # # [INFO] detected THP size: 2048 KiB
# # TAP version 13
# # 1..6
# # # [INFO] PTRACE write access
# # not ok 1 write() failed
# # # [INFO] PTRACE write access to THP
# # not ok 2 write() failed
# # # [INFO] Page migration
# # ok 3 SIGSEGV generated, page not modified
# # # [INFO] Page migration of THP
# # ok 4 SIGSEGV generated, page not modified
# # # [INFO] PTE-mapping a THP
# # ok 5 SIGSEGV generated, page not modified
# # # [INFO] UFFDIO_COPY
# # ok 6 SIGSEGV generated, page not modified
# # Bail out! 2 out of 6 tests failed
# # # Totals: pass:4 fail:2 xfail:0 xpass:0 skip:0 error:0
# # [FAIL]
# not ok 1 mkdirty # exit=1
# hwpoison_inject
# # SUMMARY: PASS=0 SKIP=0 FAIL=1
# 1..1
not ok 14 selftests: mm: ksft_mkdirty.sh # exit=1
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260429/202604290921.ac2bf5ff-lkp@intel.com
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply
* [PATCH 04/14] security/Kconfig.hardening: Remove tautological condition from CC_HAS_RANDSTRUCT
From: Nathan Chancellor @ 2026-04-29 2:59 UTC (permalink / raw)
To: Nathan Chancellor, Nicolas Schier, Bill Wendling, Justin Stitt,
Nick Desaulniers
Cc: linux-kernel, llvm, linux-kbuild, Kees Cook, Gustavo A. R. Silva,
linux-hardening, linux-security-module
In-Reply-To: <20260428-bump-minimum-supported-llvm-version-to-17-v1-0-81d9b2e8ee75@kernel.org>
Now that the minimum supported version of LLVM for building the kernel
has been raised to 17.0.1, the '!Clang || Clang >= 16' dependency for
CONFIG_CC_HAS_RANDSTRUCT is always true, so it can be removed.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: Kees Cook <kees@kernel.org>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: linux-hardening@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
---
security/Kconfig.hardening | 3 ---
1 file changed, 3 deletions(-)
diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
index e4f23c08a17a..b90cf9ed4642 100644
--- a/security/Kconfig.hardening
+++ b/security/Kconfig.hardening
@@ -274,9 +274,6 @@ endmenu
config CC_HAS_RANDSTRUCT
def_bool $(cc-option,-frandomize-layout-seed-file=/dev/null)
- # Randstruct was first added in Clang 15, but it isn't safe to use until
- # Clang 16 due to https://github.com/llvm/llvm-project/issues/60349
- depends on !CC_IS_CLANG || CLANG_VERSION >= 160000
choice
prompt "Randomize layout of sensitive kernel structures"
--
2.54.0
^ permalink raw reply related
* [PATCH 03/14] security/Kconfig.hardening: Remove tautological condition from FORTIFY_SOURCE
From: Nathan Chancellor @ 2026-04-29 2:59 UTC (permalink / raw)
To: Nathan Chancellor, Nicolas Schier, Bill Wendling, Justin Stitt,
Nick Desaulniers
Cc: linux-kernel, llvm, linux-kbuild, Kees Cook, Gustavo A. R. Silva,
linux-hardening, linux-security-module
In-Reply-To: <20260428-bump-minimum-supported-llvm-version-to-17-v1-0-81d9b2e8ee75@kernel.org>
Now that the minimum supported version of LLVM for building the kernel
has been raised to 17.0.1, the '!X86_32 || !Clang || Clang > 16'
dependency of CONFIG_FORTIFY_SOURCE is always true, so it can be
removed.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: Kees Cook <kees@kernel.org>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: linux-hardening@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
---
security/Kconfig.hardening | 2 --
1 file changed, 2 deletions(-)
diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
index a0461d648396..e4f23c08a17a 100644
--- a/security/Kconfig.hardening
+++ b/security/Kconfig.hardening
@@ -213,8 +213,6 @@ menu "Bounds checking"
config FORTIFY_SOURCE
bool "Harden common str/mem functions against buffer overflows"
depends on ARCH_HAS_FORTIFY_SOURCE
- # https://github.com/llvm/llvm-project/issues/53645
- depends on !X86_32 || !CC_IS_CLANG || CLANG_VERSION >= 160000
help
Detect overflows of buffers in common string and memory functions
where the compiler can determine and validate the buffer sizes.
--
2.54.0
^ permalink raw reply related
* [PATCH 02/14] security/Kconfig.hardening: Remove tautological condition from CC_HAS_ZERO_CALL_USED_REGS
From: Nathan Chancellor @ 2026-04-29 2:59 UTC (permalink / raw)
To: Nathan Chancellor, Nicolas Schier, Bill Wendling, Justin Stitt,
Nick Desaulniers
Cc: linux-kernel, llvm, linux-kbuild, Kees Cook, Gustavo A. R. Silva,
linux-hardening, linux-security-module
In-Reply-To: <20260428-bump-minimum-supported-llvm-version-to-17-v1-0-81d9b2e8ee75@kernel.org>
Now that the minimum supported version of LLVM for building the kernel
has been raised to 17.0.1, the '!Clang || Clang > 15.0.6' dependency for
CONFIG_CC_HAS_ZERO_CALL_USED_REGS is always true, so it can be removed.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: Kees Cook <kees@kernel.org>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: linux-hardening@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
---
security/Kconfig.hardening | 3 ---
1 file changed, 3 deletions(-)
diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
index 86f8768c63d4..a0461d648396 100644
--- a/security/Kconfig.hardening
+++ b/security/Kconfig.hardening
@@ -189,9 +189,6 @@ config INIT_ON_FREE_DEFAULT_ON
config CC_HAS_ZERO_CALL_USED_REGS
def_bool $(cc-option,-fzero-call-used-regs=used-gpr)
- # https://github.com/ClangBuiltLinux/linux/issues/1766
- # https://github.com/llvm/llvm-project/issues/59242
- depends on !CC_IS_CLANG || CLANG_VERSION > 150006
config ZERO_CALL_USED_REGS
bool "Enable register zeroing on function exit"
--
2.54.0
^ permalink raw reply related
* [PATCH 00/14] Bump minimum version of LLVM for building the kernel to 17.0.1
From: Nathan Chancellor @ 2026-04-29 2:59 UTC (permalink / raw)
To: Nathan Chancellor, Nicolas Schier, Bill Wendling, Justin Stitt,
Nick Desaulniers
Cc: linux-kernel, llvm, linux-kbuild, Jonathan Corbet, Shuah Khan,
linux-doc, Kees Cook, Gustavo A. R. Silva, linux-hardening,
linux-security-module, Rong Xu, Han Shen, Russell King,
Arnd Bergmann, linux-arm-kernel, Paul Walmsley, Palmer Dabbelt,
Albert Ou, Alexandre Ghiti, linux-riscv, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin,
Peter Zijlstra, Ard Biesheuvel
The current minimum version of LLVM for building the kernel is 15.0.0.
However, there are two deficiencies compared to GCC that were fixed in
LLVM 17 that are starting to become more noticeable.
The first was a bug in LLVM's scope checker [1], where all labels in a
function were validated as potential targets of an asm goto statement,
even if they were not listed in the asm goto statement as targets. This
becomes particularly problematic when the cleanup attribute is used, as
asm goto(... : label_a);
...
label_a:
...
int var __free(foo);
asm goto(... : label_b);
...
label_b:
...
will trigger an error since the scope checker will complain that the
cleanup variable would be skipped when jumping from the first asm goto
to label_b (which obviously cannot happen). This issue was the catalyst
for commit e2ffa15b9baa ("kbuild: Disable CC_HAS_ASM_GOTO_OUTPUT on
clang < 17"). Unfortunately, this issue is reproducible with regular asm
goto in addition to asm goto with outputs, so that change was not
entirely sufficient to avoid the issue altogether. As asm goto has
effectively been required since commit a0a12c3ed057 ("asm goto:
eradicate CC_HAS_ASM_GOTO") and the usage of the cleanup attribute
continues to grow across the tree, raising the minimum to a version that
avoids this issue altogether is a better long term solution than
attempting to workaround it at every spot where it happens.
The second issue is an incompatibility with GCC 8.1+ around variables
marked with const being valid constant expressions for _Static_assert
and other macros [2]. With GCC 8.1 being the minimum supported version
since commit 118c40b7b503 ("kbuild: require gcc-8 and binutils-2.30"),
this incompatibility becomes more of a maintenance burden since only
clang-15 and clang-16 are affected by it.
Looking at the clang version of various major distributions through
Docker images, no one should be left behind as a result of this bump, as
the old ones cannot clear the current minimum of 15.0.0.
archlinux:latest clang version 22.1.3
debian:oldoldstable-slim Debian clang version 11.0.1-2
debian:oldstable-slim Debian clang version 14.0.6
debian:stable-slim Debian clang version 19.1.7 (3+b1)
debian:testing-slim Debian clang version 21.1.8 (3+b1)
debian:unstable-slim Debian clang version 21.1.8 (7+b1)
fedora:42 clang version 20.1.8 (Fedora 20.1.8-4.fc42)
fedora:latest clang version 21.1.8 (Fedora 21.1.8-4.fc43)
fedora:44 clang version 22.1.1 (Fedora 22.1.1-2.fc44)
fedora:rawhide clang version 22.1.3 (Fedora 22.1.3-1.fc45)
opensuse/leap:latest clang version 17.0.6
opensuse/tumbleweed:latest clang version 21.1.8
ubuntu:jammy Ubuntu clang version 14.0.0-1ubuntu1.1
ubuntu:noble Ubuntu clang version 18.1.3 (1ubuntu1)
ubuntu:questing Ubuntu clang version 20.1.8 (0ubuntu4)
ubuntu:resolute Ubuntu clang version 21.1.8 (6ubuntu1)
17.0.1 is chosen as the minimum instead of 17.0.0 to ensure that the
particular version of LLVM 17 has the two aforementioned bugs fixed, as
the second was fixed during the 17.0.0 release candidate phase and it
was not until LLVM 18 that LLVM adopted the scheme of x.0.0 being a
prerelease version and x.1.0 is a release version [3] to help with
scenarios such as this.
The first patch in the series does the actual bump. The remaining
patches are cleanups of workarounds for various issues that are no
longer needed with the bump.
I plan to take this via the Kbuild tree for 7.2, please provide Acks as
necessary.
[1]: https://github.com/llvm/llvm-project/commit/f023f5cdb2e6c19026f04a15b5a935c041835d14
[2]: https://github.com/llvm/llvm-project/commit/0b2d5b967d98375793897295d651f58f6fbd3034
[3]: https://github.com/llvm/llvm-project/commit/4532617ae420056bf32f6403dde07fb99d276a49
---
Nathan Chancellor (14):
kbuild: Bump minimum version of LLVM for building the kernel to 17.0.1
security/Kconfig.hardening: Remove tautological condition from CC_HAS_ZERO_CALL_USED_REGS
security/Kconfig.hardening: Remove tautological condition from FORTIFY_SOURCE
security/Kconfig.hardening: Remove tautological condition from CC_HAS_RANDSTRUCT
arch/Kconfig: Remove tautological conditions from HAS_LTO_CLANG
arch/Kconfig: Remove tautological condition from AUTOFDO_CLANG
ARM: Drop tautological ld.lld conditions from ARCH_MULTI_V4{,T}
riscv: Remove tautological condition from selection of ARCH_SUPPORTS_CFI
riscv: Drop tautological condition from TOOLCHAIN_NEEDS_OLD_ISA_SPEC
scripts/Makefile.warn: Drop -Wformat handling for clang < 16
x86/build: Drop unused '-ffreestanding' addition to KBUILD_CFLAGS
x86/module: Revert "Deal with GOT based stack cookie load on Clang < 17"
x86/entry/vdso32: Remove conditional omission of '.cfi_offset eflags'
kbuild: Remove check for broken scoping with clang < 17 in CC_HAS_ASM_GOTO_OUTPUT
Documentation/process/changes.rst | 2 +-
arch/Kconfig | 5 +----
arch/arm/Kconfig.platforms | 4 ----
arch/riscv/Kconfig | 16 +++++++---------
arch/x86/Makefile | 5 -----
arch/x86/entry/vdso/vdso32/sigreturn.S | 10 ----------
arch/x86/include/asm/elf.h | 5 ++---
arch/x86/kernel/module.c | 15 ---------------
init/Kconfig | 3 ---
scripts/Makefile.warn | 10 ----------
scripts/min-tool-version.sh | 2 +-
security/Kconfig.hardening | 8 --------
12 files changed, 12 insertions(+), 73 deletions(-)
---
base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
change-id: 20260422-bump-minimum-supported-llvm-version-to-17-b4638a58b043
Best regards,
--
Nathan Chancellor <nathan@kernel.org>
^ permalink raw reply
* [PATCH 1/1] yama: clean-up ptrace relations upon activating YAMA_SCOPE_NO_ATTACH
From: Ethan Ferguson @ 2026-04-28 19:28 UTC (permalink / raw)
To: kees, paul, jmorris, serge
Cc: linux-security-module, linux-kernel, Ethan Ferguson
In-Reply-To: <20260428192818.1035760-1-ethan.ferguson@zetier.com>
Clean up ptracer_relations upon YAMA_SCOPE_NO_ATTACH, and prevent
further modification by processes.
Signed-off-by: Ethan Ferguson <ethan.ferguson@zetier.com>
---
security/yama/yama_lsm.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index cef3776cf3b2..3b7c5384e6bc 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -26,6 +26,7 @@
#define YAMA_SCOPE_NO_ATTACH 3
static int ptrace_scope = YAMA_SCOPE_RELATIONAL;
+static int max_scope = YAMA_SCOPE_NO_ATTACH;
/* describe a ptrace relationship for potential exception */
struct ptrace_relation {
@@ -119,7 +120,7 @@ static void yama_relation_cleanup(struct work_struct *work)
spin_lock(&ptracer_relations_lock);
rcu_read_lock();
list_for_each_entry_rcu(relation, &ptracer_relations, node) {
- if (relation->invalid) {
+ if (relation->invalid || ptrace_scope == max_scope) {
list_del_rcu(&relation->node);
kfree_rcu(relation, rcu);
}
@@ -204,7 +205,8 @@ static void yama_ptracer_del(struct task_struct *tracer,
*/
static void yama_task_free(struct task_struct *task)
{
- yama_ptracer_del(task, task);
+ if (ptrace_scope <= max_scope)
+ yama_ptracer_del(task, task);
}
/**
@@ -224,6 +226,9 @@ static int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3,
int rc = -ENOSYS;
struct task_struct *myself;
+ if (ptrace_scope == max_scope)
+ return -EPERM;
+
switch (option) {
case PR_SET_PTRACER:
/* Since a thread can call prctl(), find the group leader
@@ -432,6 +437,7 @@ static struct security_hook_list yama_hooks[] __ro_after_init = {
static int yama_dointvec_minmax(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
+ int ret;
struct ctl_table table_copy;
if (write && !capable(CAP_SYS_PTRACE))
@@ -442,10 +448,17 @@ static int yama_dointvec_minmax(const struct ctl_table *table, int write,
if (*(int *)table_copy.data == *(int *)table_copy.extra2)
table_copy.extra1 = table_copy.extra2;
- return proc_dointvec_minmax(&table_copy, write, buffer, lenp, ppos);
-}
+ ret = proc_dointvec_minmax(&table_copy, write, buffer, lenp, ppos);
+ if (ret < 0)
+ return ret;
-static int max_scope = YAMA_SCOPE_NO_ATTACH;
+ /* If max_scope was just activated in this call */
+ if (*(int *)table_copy.data == *(int *)table_copy.extra2 &&
+ table_copy.extra1 != table_copy.extra2)
+ schedule_work(&yama_relation_work);
+
+ return 0;
+}
static const struct ctl_table yama_sysctl_table[] = {
{
--
2.43.0
^ permalink raw reply related
* [PATCH 0/1] yama: clean-up ptrace relations upon activating YAMA_SCOPE_NO_ATTACH
From: Ethan Ferguson @ 2026-04-28 19:28 UTC (permalink / raw)
To: kees, paul, jmorris, serge
Cc: linux-security-module, linux-kernel, Ethan Ferguson
Once yama's ptrace_scope gets set to it's max value (currently
YAMA_SCOPE_NO_ATTACH), all ptrace actions will forever be denied.
However, processes may still add ptrace relations, and the memory
to store these relations is still allocated, even though it is never
used again.
This patch cleans up all memory related to ptracer_relations upon
YAMA_SCOPE_NO_ATTACH, and additionally disallows further modification
of ptracer_relations from processes.
Ethan Ferguson (1):
yama: clean-up ptrace relations upon activating YAMA_SCOPE_NO_ATTACH
security/yama/yama_lsm.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
base-commit: cf2f06f7152d
--
2.43.0
^ permalink raw reply
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