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

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Date:   Mon, 29 Nov 2021 12:00:56 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     linux-integrity@...r.kernel.org
Cc:     linux-fscrypt@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Eric Biggers <ebiggers@...nel.org>
Subject: [PATCH 3/4] ima: limit including fs-verity's file digest in measurement list

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@...ux.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