[PATCH 3/4] ima: limit including fs-verity's file digest in measurement list

Mimi Zohar
2021-11-29T17:03:39Z

Without the file signature included the IMA measurement list, the type
of file digest is unclear. Limit including fs-verity's file digest in
the IMA measurement list based on whether the template name is ima-sig.
In the future, this could be relaxed to include any template format that
includes the file signature.

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
---
security/integrity/ima/ima.h | 3 ++-
security/integrity/ima/ima_api.c | 3 ++-
security/integrity/ima/ima_appraise.c | 3 ++-
security/integrity/ima/ima_main.c | 7 ++++++-
security/integrity/ima/ima_template_lib.c | 3 ++-
5 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index be965a8715e4..ab257e404f8e 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -262,7 +262,8 @@ int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,
int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func);
int ima_collect_measurement(struct integrity_iint_cache *iint,
struct file *file, void *buf, loff_t size,
- enum hash_algo algo, struct modsig *modsig);
+ enum hash_algo algo, struct modsig *modsig,
+ bool veritysig);
void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
const unsigned char *filename,
struct evm_ima_xattr_data *xattr_value,
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 42c6ff7056e6..179c7f0364c2 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -217,7 +217,8 @@ int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,
*/
int ima_collect_measurement(struct integrity_iint_cache *iint,
struct file *file, void *buf, loff_t size,
- enum hash_algo algo, struct modsig *modsig)
+ enum hash_algo algo, struct modsig *modsig,
+ bool veritysig)
{
const char *audit_cause = "failed";
struct inode *inode = file_inode(file);
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index d43a27a9a9b6..b31be383e668 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -510,7 +510,8 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
!(iint->flags & IMA_HASH))
return;

- rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL);
+ rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo,
+ NULL, FALSE);
if (rc < 0)
return;

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 465865412100..a73e1e845ea8 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -216,6 +216,7 @@ static int process_measurement(struct file *file, const struct cred *cred,
bool violation_check;
enum hash_algo hash_algo;
unsigned int allowed_algos = 0;
+ int veritysig = FALSE;

if (!ima_policy_flag || !S_ISREG(inode->i_mode))
return 0;
@@ -333,8 +334,12 @@ static int process_measurement(struct file *file, const struct cred *cred,
}

hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
+ if (xattr_value && xattr_value->type == IMA_VERITY_DIGSIG &&
+ strcmp(template_desc->name, "ima-sig") == 0)
+ veritysig = TRUE;

- rc = ima_collect_measurement(iint, file, buf, size, hash_algo, modsig);
+ rc = ima_collect_measurement(iint, file, buf, size, hash_algo,
+ modsig, veritysig);
if (rc != 0 && rc != -EBADF && rc != -EINVAL)
goto out_locked;

diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index ca017cae73eb..5bad251f3b07 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -478,7 +478,8 @@ int ima_eventsig_init(struct ima_event_data *event_data,
{
struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;

- if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
+ if ((!xattr_value) || !(xattr_value->type == EVM_IMA_XATTR_DIGSIG ||
+ xattr_value->type == IMA_VERITY_DIGSIG))
return ima_eventevmsig_init(event_data, field_data);

return ima_write_template_field_data(xattr_value, event_data->xattr_len,
--
2.27.0