[PATCH v5] ima_fs: Avoid creating measurement lists for unsupported hash algos

[PATCH v5] ima_fs: Avoid creating measurement lists for unsupported hash algos

[Dmitry Safonov via B4 Relay]

From: Dmitry Safonov <dima@arista.com>

ima_tpm_chip->allocated_banks[i].crypto_id is initialized to
HASH_ALGO__LAST if the TPM algorithm is not supported. However there
are places relying on the algorithm to be valid because it is accessed
by hash_algo_name[].

On 6.12.40 I observe the following read out-of-bounds in hash_algo_name:
  ==================================================================
  BUG: KASAN: global-out-of-bounds in create_securityfs_measurement_lists+0x396/0x440
  Read of size 8 at addr ffffffff83e18138 by task swapper/0/1

  CPU: 4 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.40 #3
  Call Trace:
   <TASK>
   dump_stack_lvl+0x61/0x90
   print_report+0xc4/0x580
   ? kasan_addr_to_slab+0x26/0x80
   ? create_securityfs_measurement_lists+0x396/0x440
   kasan_report+0xc2/0x100
   ? create_securityfs_measurement_lists+0x396/0x440
   create_securityfs_measurement_lists+0x396/0x440
   ima_fs_init+0xa3/0x300
   ima_init+0x7d/0xd0
   init_ima+0x28/0x100
   do_one_initcall+0xa6/0x3e0
   kernel_init_freeable+0x455/0x740
   kernel_init+0x24/0x1d0
   ret_from_fork+0x38/0x80
   ret_from_fork_asm+0x11/0x20
   </TASK>

  The buggy address belongs to the variable:
   hash_algo_name+0xb8/0x420

  Memory state around the buggy address:
   ffffffff83e18000: 00 01 f9 f9 f9 f9 f9 f9 00 01 f9 f9 f9 f9 f9 f9
   ffffffff83e18080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  >ffffffff83e18100: 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 00 05 f9 f9
                                          ^
   ffffffff83e18180: f9 f9 f9 f9 00 00 00 00 00 00 00 04 f9 f9 f9 f9
   ffffffff83e18200: 00 00 00 00 00 00 00 00 04 f9 f9 f9 f9 f9 f9 f9
  ==================================================================

Seems like the TPM chip supports sha3_256, which isn't yet in
tpm_algorithms:
  tpm tpm0: TPM with unsupported bank algorithm 0x0027

Thus solve the problem by creating a file name with "_tpm_alg_<ID>"
postfix if the crypto algorithm isn't initialized.

This is how it looks on the test machine (patch ported to v6.12 release):
  # ls -1 /sys/kernel/security/ima/
  ascii_runtime_measurements
  ascii_runtime_measurements_tpm_alg_27
  ascii_runtime_measurements_sha1
  ascii_runtime_measurements_sha256
  binary_runtime_measurements
  binary_runtime_measurements_tpm_alg_27
  binary_runtime_measurements_sha1
  binary_runtime_measurements_sha256
  policy
  runtime_measurements_count
  violations

Fixes: 9fa8e7625008 ("ima: add crypto agility support for template-hash algorithm")
Signed-off-by: Dmitry Safonov <dima@arista.com>
Cc: Enrico Bravi <enrico.bravi@polito.it>
Cc: Silvia Sisinni <silvia.sisinni@polito.it>
Cc: Roberto Sassu <roberto.sassu@huawei.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
---
Changes in v5:
- Use lower-case for sysfs file name (as suggested-by Jonathan and Roberto)
- Don't use email quotes for patch description (Roberto)
- Re-word the patch description (suggested-by Roberto)
- Link to v4: https://lore.kernel.org/r/20260127-ima-oob-v4-1-bf0cd7f9b4d4@arista.com

Changes in v4:
- Use ima_tpm_chip->allocated_banks[algo_idx].digest_size instead of hash_digest_size[algo]
  (Roberto Sassu)
- Link to v3: https://lore.kernel.org/r/20260127-ima-oob-v3-1-1dd09f4c2a6a@arista.com
Testing note: I test it on v6.12.40 kernel backport, which slightly differs as
lookup_template_data_hash_algo() was yet present.

Changes in v3:
- Now fix the spelling *for real* (sorry, messed it up in v2)
- Link to v2: https://lore.kernel.org/r/20260127-ima-oob-v2-1-f38a18c850cf@arista.com

Changes in v2:
- Instead of skipping unknown algorithms, add files under their TPM_ALG_ID (Roberto Sassu)
- Fix spelling (Roberto Sassu)
- Copy @stable on the fix
- Link to v1: https://lore.kernel.org/r/20260127-ima-oob-v1-1-2d42f3418e57@arista.com
---
 security/integrity/ima/ima_fs.c | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 012a58959ff0..3d9996ed486d 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -132,16 +132,12 @@ int ima_measurements_show(struct seq_file *m, void *v)
 	char *template_name;
 	u32 pcr, namelen, template_data_len; /* temporary fields */
 	bool is_ima_template = false;
-	enum hash_algo algo;
 	int i, algo_idx;
 
 	algo_idx = ima_sha1_idx;
-	algo = HASH_ALGO_SHA1;
 
-	if (m->file != NULL) {
+	if (m->file != NULL)
 		algo_idx = (unsigned long)file_inode(m->file)->i_private;
-		algo = ima_algo_array[algo_idx].algo;
-	}
 
 	/* get entry */
 	e = qe->entry;
@@ -160,7 +156,8 @@ int ima_measurements_show(struct seq_file *m, void *v)
 	ima_putc(m, &pcr, sizeof(e->pcr));
 
 	/* 2nd: template digest */
-	ima_putc(m, e->digests[algo_idx].digest, hash_digest_size[algo]);
+	ima_putc(m, e->digests[algo_idx].digest,
+		 ima_tpm_chip->allocated_banks[algo_idx].digest_size);
 
 	/* 3rd: template name size */
 	namelen = !ima_canonical_fmt ? strlen(template_name) :
@@ -229,16 +226,12 @@ static int ima_ascii_measurements_show(struct seq_file *m, void *v)
 	struct ima_queue_entry *qe = v;
 	struct ima_template_entry *e;
 	char *template_name;
-	enum hash_algo algo;
 	int i, algo_idx;
 
 	algo_idx = ima_sha1_idx;
-	algo = HASH_ALGO_SHA1;
 
-	if (m->file != NULL) {
+	if (m->file != NULL)
 		algo_idx = (unsigned long)file_inode(m->file)->i_private;
-		algo = ima_algo_array[algo_idx].algo;
-	}
 
 	/* get entry */
 	e = qe->entry;
@@ -252,7 +245,8 @@ static int ima_ascii_measurements_show(struct seq_file *m, void *v)
 	seq_printf(m, "%2d ", e->pcr);
 
 	/* 2nd: template hash */
-	ima_print_digest(m, e->digests[algo_idx].digest, hash_digest_size[algo]);
+	ima_print_digest(m, e->digests[algo_idx].digest,
+			 ima_tpm_chip->allocated_banks[algo_idx].digest_size);
 
 	/* 3th:  template name */
 	seq_printf(m, " %s", template_name);
@@ -404,16 +398,24 @@ static int __init create_securityfs_measurement_lists(void)
 		char file_name[NAME_MAX + 1];
 		struct dentry *dentry;
 
-		sprintf(file_name, "ascii_runtime_measurements_%s",
-			hash_algo_name[algo]);
+		if (algo == HASH_ALGO__LAST)
+			sprintf(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]);
 		dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
 						ima_dir, (void *)(uintptr_t)i,
 						&ima_ascii_measurements_ops);
 		if (IS_ERR(dentry))
 			return PTR_ERR(dentry);
 
-		sprintf(file_name, "binary_runtime_measurements_%s",
-			hash_algo_name[algo]);
+		if (algo == HASH_ALGO__LAST)
+			sprintf(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]);
 		dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
 						ima_dir, (void *)(uintptr_t)i,
 						&ima_measurements_ops);

---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20260127-ima-oob-9fa83a634d7b

Best regards,
-- 
Dmitry Safonov <dima@arista.com>

Re: [PATCH v5] ima_fs: Avoid creating measurement lists for unsupported hash algos

[Roberto Sassu]

On Mon, 2026-02-23 at 14:56 +0000, Dmitry Safonov via B4 Relay wrote:
> From: Dmitry Safonov <dima@arista.com>
> 
> ima_tpm_chip->allocated_banks[i].crypto_id is initialized to
> HASH_ALGO__LAST if the TPM algorithm is not supported. However there
> are places relying on the algorithm to be valid because it is accessed
> by hash_algo_name[].
> 
> On 6.12.40 I observe the following read out-of-bounds in hash_algo_name:
>   ==================================================================
>   BUG: KASAN: global-out-of-bounds in create_securityfs_measurement_lists+0x396/0x440
>   Read of size 8 at addr ffffffff83e18138 by task swapper/0/1
> 
>   CPU: 4 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.40 #3
>   Call Trace:
>    <TASK>
>    dump_stack_lvl+0x61/0x90
>    print_report+0xc4/0x580
>    ? kasan_addr_to_slab+0x26/0x80
>    ? create_securityfs_measurement_lists+0x396/0x440
>    kasan_report+0xc2/0x100
>    ? create_securityfs_measurement_lists+0x396/0x440
>    create_securityfs_measurement_lists+0x396/0x440
>    ima_fs_init+0xa3/0x300
>    ima_init+0x7d/0xd0
>    init_ima+0x28/0x100
>    do_one_initcall+0xa6/0x3e0
>    kernel_init_freeable+0x455/0x740
>    kernel_init+0x24/0x1d0
>    ret_from_fork+0x38/0x80
>    ret_from_fork_asm+0x11/0x20
>    </TASK>
> 
>   The buggy address belongs to the variable:
>    hash_algo_name+0xb8/0x420
> 
>   Memory state around the buggy address:
>    ffffffff83e18000: 00 01 f9 f9 f9 f9 f9 f9 00 01 f9 f9 f9 f9 f9 f9
>    ffffffff83e18080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   >ffffffff83e18100: 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 00 05 f9 f9
>                                           ^
>    ffffffff83e18180: f9 f9 f9 f9 00 00 00 00 00 00 00 04 f9 f9 f9 f9
>    ffffffff83e18200: 00 00 00 00 00 00 00 00 04 f9 f9 f9 f9 f9 f9 f9
>   ==================================================================
> 
> Seems like the TPM chip supports sha3_256, which isn't yet in
> tpm_algorithms:
>   tpm tpm0: TPM with unsupported bank algorithm 0x0027
> 
> Thus solve the problem by creating a file name with "_tpm_alg_<ID>"
> postfix if the crypto algorithm isn't initialized.
> 
> This is how it looks on the test machine (patch ported to v6.12 release):
>   # ls -1 /sys/kernel/security/ima/
>   ascii_runtime_measurements
>   ascii_runtime_measurements_tpm_alg_27
>   ascii_runtime_measurements_sha1
>   ascii_runtime_measurements_sha256
>   binary_runtime_measurements
>   binary_runtime_measurements_tpm_alg_27
>   binary_runtime_measurements_sha1
>   binary_runtime_measurements_sha256
>   policy
>   runtime_measurements_count
>   violations
> 
> Fixes: 9fa8e7625008 ("ima: add crypto agility support for template-hash algorithm")
> Signed-off-by: Dmitry Safonov <dima@arista.com>
> Cc: Enrico Bravi <enrico.bravi@polito.it>
> Cc: Silvia Sisinni <silvia.sisinni@polito.it>
> Cc: Roberto Sassu <roberto.sassu@huawei.com>
> Cc: Mimi Zohar <zohar@linux.ibm.com>
> ---
> Changes in v5:
> - Use lower-case for sysfs file name (as suggested-by Jonathan and Roberto)
> - Don't use email quotes for patch description (Roberto)
> - Re-word the patch description (suggested-by Roberto)
> - Link to v4: https://lore.kernel.org/r/20260127-ima-oob-v4-1-bf0cd7f9b4d4@arista.com
> 
> Changes in v4:
> - Use ima_tpm_chip->allocated_banks[algo_idx].digest_size instead of hash_digest_size[algo]
>   (Roberto Sassu)
> - Link to v3: https://lore.kernel.org/r/20260127-ima-oob-v3-1-1dd09f4c2a6a@arista.com
> Testing note: I test it on v6.12.40 kernel backport, which slightly differs as
> lookup_template_data_hash_algo() was yet present.
> 
> Changes in v3:
> - Now fix the spelling *for real* (sorry, messed it up in v2)
> - Link to v2: https://lore.kernel.org/r/20260127-ima-oob-v2-1-f38a18c850cf@arista.com
> 
> Changes in v2:
> - Instead of skipping unknown algorithms, add files under their TPM_ALG_ID (Roberto Sassu)
> - Fix spelling (Roberto Sassu)
> - Copy @stable on the fix
> - Link to v1: https://lore.kernel.org/r/20260127-ima-oob-v1-1-2d42f3418e57@arista.com
> ---
>  security/integrity/ima/ima_fs.c | 34 ++++++++++++++++++----------------
>  1 file changed, 18 insertions(+), 16 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
> index 012a58959ff0..3d9996ed486d 100644
> --- a/security/integrity/ima/ima_fs.c
> +++ b/security/integrity/ima/ima_fs.c
> @@ -132,16 +132,12 @@ int ima_measurements_show(struct seq_file *m, void *v)
>  	char *template_name;
>  	u32 pcr, namelen, template_data_len; /* temporary fields */
>  	bool is_ima_template = false;
> -	enum hash_algo algo;
>  	int i, algo_idx;
>  
>  	algo_idx = ima_sha1_idx;
> -	algo = HASH_ALGO_SHA1;
>  
> -	if (m->file != NULL) {
> +	if (m->file != NULL)
>  		algo_idx = (unsigned long)file_inode(m->file)->i_private;
> -		algo = ima_algo_array[algo_idx].algo;
> -	}
>  
>  	/* get entry */
>  	e = qe->entry;
> @@ -160,7 +156,8 @@ int ima_measurements_show(struct seq_file *m, void *v)
>  	ima_putc(m, &pcr, sizeof(e->pcr));
>  
>  	/* 2nd: template digest */
> -	ima_putc(m, e->digests[algo_idx].digest, hash_digest_size[algo]);
> +	ima_putc(m, e->digests[algo_idx].digest,
> +		 ima_tpm_chip->allocated_banks[algo_idx].digest_size);
>  
>  	/* 3rd: template name size */
>  	namelen = !ima_canonical_fmt ? strlen(template_name) :
> @@ -229,16 +226,12 @@ static int ima_ascii_measurements_show(struct seq_file *m, void *v)
>  	struct ima_queue_entry *qe = v;
>  	struct ima_template_entry *e;
>  	char *template_name;
> -	enum hash_algo algo;
>  	int i, algo_idx;
>  
>  	algo_idx = ima_sha1_idx;
> -	algo = HASH_ALGO_SHA1;
>  
> -	if (m->file != NULL) {
> +	if (m->file != NULL)
>  		algo_idx = (unsigned long)file_inode(m->file)->i_private;
> -		algo = ima_algo_array[algo_idx].algo;
> -	}
>  
>  	/* get entry */
>  	e = qe->entry;
> @@ -252,7 +245,8 @@ static int ima_ascii_measurements_show(struct seq_file *m, void *v)
>  	seq_printf(m, "%2d ", e->pcr);
>  
>  	/* 2nd: template hash */
> -	ima_print_digest(m, e->digests[algo_idx].digest, hash_digest_size[algo]);
> +	ima_print_digest(m, e->digests[algo_idx].digest,
> +			 ima_tpm_chip->allocated_banks[algo_idx].digest_size);

Sorry, I realized that this does not work if SHA1 or the default hash
algorithm are not among allocated PCR banks.

I just sent a patch to correctly determine the digest size:

https://marc.info/?l=linux-integrity&m=177202677128752&w=2

and applied yours on top of that (if it is fine for you):

https://github.com/linux-integrity/linux/commit/6efbd2b38b102ecbadc350228cc30fd67666a089


Thanks

Roberto

>  
>  	/* 3th:  template name */
>  	seq_printf(m, " %s", template_name);
> @@ -404,16 +398,24 @@ static int __init create_securityfs_measurement_lists(void)
>  		char file_name[NAME_MAX + 1];
>  		struct dentry *dentry;
>  
> -		sprintf(file_name, "ascii_runtime_measurements_%s",
> -			hash_algo_name[algo]);
> +		if (algo == HASH_ALGO__LAST)
> +			sprintf(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]);
>  		dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
>  						ima_dir, (void *)(uintptr_t)i,
>  						&ima_ascii_measurements_ops);
>  		if (IS_ERR(dentry))
>  			return PTR_ERR(dentry);
>  
> -		sprintf(file_name, "binary_runtime_measurements_%s",
> -			hash_algo_name[algo]);
> +		if (algo == HASH_ALGO__LAST)
> +			sprintf(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]);
>  		dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
>  						ima_dir, (void *)(uintptr_t)i,
>  						&ima_measurements_ops);
> 
> ---
> base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
> change-id: 20260127-ima-oob-9fa83a634d7b
> 
> Best regards,

Re: [PATCH v5] ima_fs: Avoid creating measurement lists for unsupported hash algos

[Dmitry Safonov]

On Wed, Feb 25, 2026 at 1:20 PM Roberto Sassu
<roberto.sassu@huaweicloud.com> wrote:
>
> On Mon, 2026-02-23 at 14:56 +0000, Dmitry Safonov via B4 Relay wrote:
[..]
> > @@ -252,7 +245,8 @@ static int ima_ascii_measurements_show(struct seq_file *m, void *v)
> >       seq_printf(m, "%2d ", e->pcr);
> >
> >       /* 2nd: template hash */
> > -     ima_print_digest(m, e->digests[algo_idx].digest, hash_digest_size[algo]);
> > +     ima_print_digest(m, e->digests[algo_idx].digest,
> > +                      ima_tpm_chip->allocated_banks[algo_idx].digest_size);
>
> Sorry, I realized that this does not work if SHA1 or the default hash
> algorithm are not among allocated PCR banks.
>
> I just sent a patch to correctly determine the digest size:
>
> https://marc.info/?l=linux-integrity&m=177202677128752&w=2
>
> and applied yours on top of that (if it is fine for you):
>
> https://github.com/linux-integrity/linux/commit/6efbd2b38b102ecbadc350228cc30fd67666a089
>

Thanks!
            Dmitry

Re: [PATCH v5] ima_fs: Avoid creating measurement lists for unsupported hash algos

[Mimi Zohar]

On Mon, 2026-02-23 at 14:56 +0000, Dmitry Safonov via B4 Relay wrote:
> From: Dmitry Safonov <dima@arista.com>
> 
> ima_tpm_chip->allocated_banks[i].crypto_id is initialized to
> HASH_ALGO__LAST if the TPM algorithm is not supported. However there
> are places relying on the algorithm to be valid because it is accessed
> by hash_algo_name[].
> 
> On 6.12.40 I observe the following read out-of-bounds in hash_algo_name:
>   ==================================================================
>   BUG: KASAN: global-out-of-bounds in create_securityfs_measurement_lists+0x396/0x440
>   Read of size 8 at addr ffffffff83e18138 by task swapper/0/1
> 
>   CPU: 4 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.40 #3
>   Call Trace:
>    <TASK>
>    dump_stack_lvl+0x61/0x90
>    print_report+0xc4/0x580
>    ? kasan_addr_to_slab+0x26/0x80
>    ? create_securityfs_measurement_lists+0x396/0x440
>    kasan_report+0xc2/0x100
>    ? create_securityfs_measurement_lists+0x396/0x440
>    create_securityfs_measurement_lists+0x396/0x440
>    ima_fs_init+0xa3/0x300
>    ima_init+0x7d/0xd0
>    init_ima+0x28/0x100
>    do_one_initcall+0xa6/0x3e0
>    kernel_init_freeable+0x455/0x740
>    kernel_init+0x24/0x1d0
>    ret_from_fork+0x38/0x80
>    ret_from_fork_asm+0x11/0x20
>    </TASK>
> 
>   The buggy address belongs to the variable:
>    hash_algo_name+0xb8/0x420
> 
>   Memory state around the buggy address:
>    ffffffff83e18000: 00 01 f9 f9 f9 f9 f9 f9 00 01 f9 f9 f9 f9 f9 f9
>    ffffffff83e18080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   >ffffffff83e18100: 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 00 05 f9 f9
>                                           ^
>    ffffffff83e18180: f9 f9 f9 f9 00 00 00 00 00 00 00 04 f9 f9 f9 f9
>    ffffffff83e18200: 00 00 00 00 00 00 00 00 04 f9 f9 f9 f9 f9 f9 f9
>   ==================================================================
> 
> Seems like the TPM chip supports sha3_256, which isn't yet in
> tpm_algorithms:
>   tpm tpm0: TPM with unsupported bank algorithm 0x0027
> 
> Thus solve the problem by creating a file name with "_tpm_alg_<ID>"
> postfix if the crypto algorithm isn't initialized.
> 
> This is how it looks on the test machine (patch ported to v6.12 release):
>   # ls -1 /sys/kernel/security/ima/
>   ascii_runtime_measurements
>   ascii_runtime_measurements_tpm_alg_27
>   ascii_runtime_measurements_sha1
>   ascii_runtime_measurements_sha256
>   binary_runtime_measurements
>   binary_runtime_measurements_tpm_alg_27
>   binary_runtime_measurements_sha1
>   binary_runtime_measurements_sha256
>   policy
>   runtime_measurements_count
>   violations

When reposting this patch, on top of Roberto's patch, please include the name of
the TCG document, or a link to it, defining the algorithm id number here in the
patch description.

thanks,

Mimi

Re: [PATCH v5] ima_fs: Avoid creating measurement lists for unsupported hash algos

[Mimi Zohar]

On Mon, 2026-02-23 at 14:56 +0000, Dmitry Safonov via B4 Relay wrote:
> From: Dmitry Safonov <dima@arista.com>
> 
> ima_tpm_chip->allocated_banks[i].crypto_id is initialized to
> HASH_ALGO__LAST if the TPM algorithm is not supported. However there
> are places relying on the algorithm to be valid because it is accessed
> by hash_algo_name[].

If the TPM algorithm is not supported by whom? the kernel?  HASH_ALGO__LAST is
defined in linux/hash_info.h.  If the crypto algorithm is not supported by the
kernel, then the kernel won't be able to calculate the hash to extend the TPM.

> @@ -404,16 +398,24 @@ static int __init create_securityfs_measurement_lists(void)
>  		char file_name[NAME_MAX + 1];
>  		struct dentry *dentry;
>  
> -		sprintf(file_name, "ascii_runtime_measurements_%s",
> -			hash_algo_name[algo]);
> +		if (algo == HASH_ALGO__LAST)
> +			sprintf(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]);
>  		dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
>  						ima_dir, (void *)(uintptr_t)i,
>  						&ima_ascii_measurements_ops);
>  		if (IS_ERR(dentry))
>  			return PTR_ERR(dentry);
>  
> -		sprintf(file_name, "binary_runtime_measurements_%s",
> -			hash_algo_name[algo]);
> +		if (algo == HASH_ALGO__LAST)
> +			sprintf(file_name, "binary_runtime_measurements_tpm_alg_%x",
> +				ima_tpm_chip->allocated_banks[i].alg_id);

There's no point in creating either of the securityfs files if the kernel
doesn't support the hash algorithm.

Mimi


> +		else
> +			sprintf(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);

Re: [PATCH v5] ima_fs: Avoid creating measurement lists for unsupported hash algos

[Roberto Sassu]

On Wed, 2026-02-25 at 15:36 -0500, Mimi Zohar wrote:
> On Mon, 2026-02-23 at 14:56 +0000, Dmitry Safonov via B4 Relay wrote:
> > From: Dmitry Safonov <dima@arista.com>
> > 
> > ima_tpm_chip->allocated_banks[i].crypto_id is initialized to
> > HASH_ALGO__LAST if the TPM algorithm is not supported. However there
> > are places relying on the algorithm to be valid because it is accessed
> > by hash_algo_name[].
> 
> If the TPM algorithm is not supported by whom? the kernel?  HASH_ALGO__LAST is
> defined in linux/hash_info.h.  If the crypto algorithm is not supported by the
> kernel, then the kernel won't be able to calculate the hash to extend the TPM.

Yes, by the kernel. True, that is why we do a padded SHA1.

> > @@ -404,16 +398,24 @@ static int __init create_securityfs_measurement_lists(void)
> >  		char file_name[NAME_MAX + 1];
> >  		struct dentry *dentry;
> >  
> > -		sprintf(file_name, "ascii_runtime_measurements_%s",
> > -			hash_algo_name[algo]);
> > +		if (algo == HASH_ALGO__LAST)
> > +			sprintf(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]);
> >  		dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
> >  						ima_dir, (void *)(uintptr_t)i,
> >  						&ima_ascii_measurements_ops);
> >  		if (IS_ERR(dentry))
> >  			return PTR_ERR(dentry);
> >  
> > -		sprintf(file_name, "binary_runtime_measurements_%s",
> > -			hash_algo_name[algo]);
> > +		if (algo == HASH_ALGO__LAST)
> > +			sprintf(file_name, "binary_runtime_measurements_tpm_alg_%x",
> > +				ima_tpm_chip->allocated_banks[i].alg_id);
> 
> There's no point in creating either of the securityfs files if the kernel
> doesn't support the hash algorithm.

It is not useful per se, but since it is an information that it is
produced and maintained by IMA, we can print it. And second, it will
expose the fact that there is an unsupported algorithm (in the case of
SHA3-256, the fix is add to the TPM - crypto subsystem mapping in tpm2-
cmd.c).

Roberto

> Mimi
> 
> 
> > +		else
> > +			sprintf(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);
> 
> 

Re: [PATCH v5] ima_fs: Avoid creating measurement lists for unsupported hash algos

[Mimi Zohar]

> > > @@ -404,16 +398,24 @@ static int __init create_securityfs_measurement_lists(void)
> > >  		char file_name[NAME_MAX + 1];
> > >  		struct dentry *dentry;
> > >  
> > > -		sprintf(file_name, "ascii_runtime_measurements_%s",
> > > -			hash_algo_name[algo]);
> > > +		if (algo == HASH_ALGO__LAST)
> > > +			sprintf(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]);
> > >  		dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
> > >  						ima_dir, (void *)(uintptr_t)i,
> > >  						&ima_ascii_measurements_ops);
> > >  		if (IS_ERR(dentry))
> > >  			return PTR_ERR(dentry);
> > >  
> > > -		sprintf(file_name, "binary_runtime_measurements_%s",
> > > -			hash_algo_name[algo]);
> > > +		if (algo == HASH_ALGO__LAST)
> > > +			sprintf(file_name, "binary_runtime_measurements_tpm_alg_%x",
> > > +				ima_tpm_chip->allocated_banks[i].alg_id);
> > 
> > There's no point in creating either of the securityfs files if the kernel
> > doesn't support the hash algorithm.
> 
> It is not useful per se, but since it is an information that it is
> produced and maintained by IMA, we can print it. And second, it will
> expose the fact that there is an unsupported algorithm (in the case of
> SHA3-256, the fix is add to the TPM - crypto subsystem mapping in tpm2-
> cmd.c).

Yes, agreed.

Dmitry, the Subject line implies the measurement lists aren't being created, yet
you're actually creating them.  Please update the patch description before re-
posting.

thanks,

Mimi