[PATCH 0/3] ima: Provide more info about buffer measurement

[PATCH 0/3] ima: Provide more info about buffer measurement

[Roberto Sassu]

This patch set provides more information about buffer measurement.

First, it introduces the new function ima_get_current_hash_algo(), to
obtain the algorithm used to calculate the buffer digest (patch 1).

Second, it changes the type of return value of ima_measure_critical_data()
and process_buffer_measurement() from void to int, to signal to the callers
whether or not the buffer has been measured, or just the digest has been
calculated and written to the supplied location (patch 2).

Lastly, it adds a new parameter to the functions above, so that those
functions can write the buffer digest to the location supplied by the
callers (patch 3).

This patch set replaces the patch 'ima: Add digest, algo, measured
parameters to ima_measure_critical_data()' in:

https://lore.kernel.org/linux-integrity/20210625165614.2284243-1-roberto.sassu@huawei.com/

Changelog

Huawei Digest Lists patch set:
- introduce ima_get_current_hash_algo() (suggested by Mimi)
- remove algo and measured parameters from ima_measure_critical_data() and
  process_buffer_measurement() (suggested by Mimi)
- return an integer from ima_measure_critical_data() and
  process_buffer_measurement() (suggested by Mimi)
- correctly check when process_buffer_measurement() should return earlier

Roberto Sassu (3):
  ima: Introduce ima_get_current_hash_algo()
  ima: Return int in the functions to measure a buffer
  ima: Add digest parameter to the functions to measure a buffer

 include/linux/ima.h                          | 22 +++++--
 security/integrity/ima/ima.h                 | 10 +--
 security/integrity/ima/ima_appraise.c        |  6 +-
 security/integrity/ima/ima_asymmetric_keys.c |  6 +-
 security/integrity/ima/ima_init.c            |  6 +-
 security/integrity/ima/ima_main.c            | 66 +++++++++++++-------
 security/integrity/ima/ima_queue_keys.c      | 15 ++---
 security/selinux/ima.c                       | 10 +--
 8 files changed, 92 insertions(+), 49 deletions(-)

-- 
2.25.1

[PATCH 1/3] ima: Introduce ima_get_current_hash_algo()

[Roberto Sassu]

This patch introduces the new function ima_get_current_hash_algo(), that
callers in the other kernel subsystems might use to obtain the hash
algorithm selected by IMA.

Its primary use will be to determine which algorithm has been used to
calculate the digest written by ima_measure_critical_data() to the location
passed as a new parameter (in a subsequent patch).

Since the hash algorithm does not change after the IMA setup phase, there
is no risk of races (obtaining a digest calculated with a different
algorithm than the one returned).

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
 include/linux/ima.h               | 7 +++++++
 security/integrity/ima/ima_main.c | 5 +++++
 2 files changed, 12 insertions(+)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 61d5723ec303..81e830d01ced 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -11,9 +11,11 @@
 #include <linux/fs.h>
 #include <linux/security.h>
 #include <linux/kexec.h>
+#include <crypto/hash_info.h>
 struct linux_binprm;
 
 #ifdef CONFIG_IMA
+extern enum hash_algo ima_get_current_hash_algo(void);
 extern int ima_bprm_check(struct linux_binprm *bprm);
 extern int ima_file_check(struct file *file, int mask);
 extern void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
@@ -64,6 +66,11 @@ static inline const char * const *arch_get_ima_policy(void)
 #endif
 
 #else
+static inline enum hash_algo ima_get_current_hash_algo(void)
+{
+	return HASH_ALGO__LAST;
+}
+
 static inline int ima_bprm_check(struct linux_binprm *bprm)
 {
 	return 0;
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 287b90509006..8ef1fa357e0c 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -76,6 +76,11 @@ static int __init hash_setup(char *str)
 }
 __setup("ima_hash=", hash_setup);
 
+enum hash_algo ima_get_current_hash_algo(void)
+{
+	return ima_hash_algo;
+}
+
 /* Prevent mmap'ing a file execute that is already mmap'ed write */
 static int mmap_violation_check(enum ima_hooks func, struct file *file,
 				char **pathbuf, const char **pathname,
-- 
2.25.1

[PATCH 2/3] ima: Return int in the functions to measure a buffer

[Roberto Sassu]

ima_measure_critical_data() and process_buffer_measurement() currently
don't return a result. A caller wouldn't be able to know whether those
functions were executed successfully.

This patch modifies the return type from void to int, and returns 0 if the
buffer has been successfully measured, a negative value otherwise.

Also, this patch does not modify the behavior of existing callers by
processing the returned value. Instead, the value is stored in a variable
marked as __maybe_unused.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
 include/linux/ima.h                          | 15 ++++---
 security/integrity/ima/ima.h                 | 10 ++---
 security/integrity/ima/ima_appraise.c        |  4 +-
 security/integrity/ima/ima_asymmetric_keys.c |  4 +-
 security/integrity/ima/ima_init.c            |  6 ++-
 security/integrity/ima/ima_main.c            | 46 ++++++++++++--------
 security/integrity/ima/ima_queue_keys.c      | 15 ++++---
 security/selinux/ima.c                       | 10 +++--
 8 files changed, 65 insertions(+), 45 deletions(-)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 81e830d01ced..60492263aa64 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -35,10 +35,10 @@ extern void ima_post_path_mknod(struct user_namespace *mnt_userns,
 extern int ima_file_hash(struct file *file, char *buf, size_t buf_size);
 extern int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size);
 extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size);
-extern void ima_measure_critical_data(const char *event_label,
-				      const char *event_name,
-				      const void *buf, size_t buf_len,
-				      bool hash);
+extern int ima_measure_critical_data(const char *event_label,
+				     const char *event_name,
+				     const void *buf, size_t buf_len,
+				     bool hash);
 
 #ifdef CONFIG_IMA_APPRAISE_BOOTPARAM
 extern void ima_appraise_parse_cmdline(void);
@@ -144,10 +144,13 @@ static inline int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size
 
 static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {}
 
-static inline void ima_measure_critical_data(const char *event_label,
+static inline int ima_measure_critical_data(const char *event_label,
 					     const char *event_name,
 					     const void *buf, size_t buf_len,
-					     bool hash) {}
+					     bool hash)
+{
+	return -ENOENT;
+}
 
 #endif /* CONFIG_IMA */
 
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index f0e448ed1f9f..03db221324c3 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -264,11 +264,11 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
 			   struct evm_ima_xattr_data *xattr_value,
 			   int xattr_len, const struct modsig *modsig, int pcr,
 			   struct ima_template_desc *template_desc);
-void process_buffer_measurement(struct user_namespace *mnt_userns,
-				struct inode *inode, const void *buf, int size,
-				const char *eventname, enum ima_hooks func,
-				int pcr, const char *func_data,
-				bool buf_hash);
+int process_buffer_measurement(struct user_namespace *mnt_userns,
+			       struct inode *inode, const void *buf, int size,
+			       const char *eventname, enum ima_hooks func,
+			       int pcr, const char *func_data,
+			       bool buf_hash);
 void ima_audit_measurement(struct integrity_iint_cache *iint,
 			   const unsigned char *filename);
 int ima_alloc_init_template(struct ima_event_data *event_data,
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index ef9dcfce45d4..275a2377743f 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -345,6 +345,7 @@ int ima_check_blacklist(struct integrity_iint_cache *iint,
 	enum hash_algo hash_algo;
 	const u8 *digest = NULL;
 	u32 digestsize = 0;
+	int process_rc __maybe_unused;
 	int rc = 0;
 
 	if (!(iint->flags & IMA_CHECK_BLACKLIST))
@@ -355,7 +356,8 @@ int ima_check_blacklist(struct integrity_iint_cache *iint,
 
 		rc = is_binary_blacklisted(digest, digestsize);
 		if ((rc == -EPERM) && (iint->flags & IMA_MEASURE))
-			process_buffer_measurement(&init_user_ns, NULL, digest, digestsize,
+			process_rc = process_buffer_measurement(&init_user_ns,
+						   NULL, digest, digestsize,
 						   "blacklisted-hash", NONE,
 						   pcr, NULL, false);
 	}
diff --git a/security/integrity/ima/ima_asymmetric_keys.c b/security/integrity/ima/ima_asymmetric_keys.c
index c985418698a4..910367cdd920 100644
--- a/security/integrity/ima/ima_asymmetric_keys.c
+++ b/security/integrity/ima/ima_asymmetric_keys.c
@@ -31,6 +31,7 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
 				   unsigned long flags, bool create)
 {
 	bool queued = false;
+	int ret __maybe_unused;
 
 	/* Only asymmetric keys are handled by this hook. */
 	if (key->type != &key_type_asymmetric)
@@ -60,7 +61,8 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
 	 * if the IMA policy is configured to measure a key linked
 	 * to the given keyring.
 	 */
-	process_buffer_measurement(&init_user_ns, NULL, payload, payload_len,
+	ret = process_buffer_measurement(&init_user_ns, NULL,
+				   payload, payload_len,
 				   keyring->description, KEY_CHECK, 0,
 				   keyring->description, false);
 }
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index 5076a7d9d23e..6790eea88db8 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -118,6 +118,7 @@ void __init ima_load_x509(void)
 
 int __init ima_init(void)
 {
+	int measure_rc __maybe_unused;
 	int rc;
 
 	ima_tpm_chip = tpm_default_chip();
@@ -153,8 +154,9 @@ int __init ima_init(void)
 
 	ima_init_key_queue();
 
-	ima_measure_critical_data("kernel_info", "kernel_version",
-				  UTS_RELEASE, strlen(UTS_RELEASE), false);
+	measure_rc = ima_measure_critical_data("kernel_info", "kernel_version",
+					       UTS_RELEASE, strlen(UTS_RELEASE),
+					       false);
 
 	return rc;
 }
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 8ef1fa357e0c..45e048899b2f 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -840,12 +840,15 @@ int ima_post_load_data(char *buf, loff_t size,
  * @buf_hash: measure buffer data hash
  *
  * Based on policy, either the buffer data or buffer data hash is measured
+ *
+ * Returns 0 if the buffer has been successfully measured, a negative value
+ * otherwise.
  */
-void process_buffer_measurement(struct user_namespace *mnt_userns,
-				struct inode *inode, const void *buf, int size,
-				const char *eventname, enum ima_hooks func,
-				int pcr, const char *func_data,
-				bool buf_hash)
+int process_buffer_measurement(struct user_namespace *mnt_userns,
+			       struct inode *inode, const void *buf, int size,
+			       const char *eventname, enum ima_hooks func,
+			       int pcr, const char *func_data,
+			       bool buf_hash)
 {
 	int ret = 0;
 	const char *audit_cause = "ENOMEM";
@@ -867,7 +870,7 @@ void process_buffer_measurement(struct user_namespace *mnt_userns,
 	u32 secid;
 
 	if (!ima_policy_flag)
-		return;
+		return -ENOENT;
 
 	template = ima_template_desc_buf();
 	if (!template) {
@@ -889,7 +892,7 @@ void process_buffer_measurement(struct user_namespace *mnt_userns,
 					secid, 0, func, &pcr, &template,
 					func_data);
 		if (!(action & IMA_MEASURE))
-			return;
+			return -ENOENT;
 	}
 
 	if (!pcr)
@@ -937,7 +940,7 @@ void process_buffer_measurement(struct user_namespace *mnt_userns,
 					func_measure_str(func),
 					audit_cause, ret, 0, ret);
 
-	return;
+	return ret;
 }
 
 /**
@@ -951,6 +954,7 @@ void process_buffer_measurement(struct user_namespace *mnt_userns,
 void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
 {
 	struct fd f;
+	int ret __maybe_unused;
 
 	if (!buf || !size)
 		return;
@@ -959,9 +963,10 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
 	if (!f.file)
 		return;
 
-	process_buffer_measurement(file_mnt_user_ns(f.file), file_inode(f.file),
-				   buf, size, "kexec-cmdline", KEXEC_CMDLINE, 0,
-				   NULL, false);
+	ret = process_buffer_measurement(file_mnt_user_ns(f.file),
+					 file_inode(f.file), buf, size,
+					 "kexec-cmdline", KEXEC_CMDLINE, 0,
+					 NULL, false);
 	fdput(f);
 }
 
@@ -977,18 +982,21 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
  * and extend the pcr.  Examples of critical data could be various data
  * structures, policies, and states stored in kernel memory that can
  * impact the integrity of the system.
+ *
+ * Returns 0 if the buffer has been successfully measured, a negative value
+ * otherwise.
  */
-void ima_measure_critical_data(const char *event_label,
-			       const char *event_name,
-			       const void *buf, size_t buf_len,
-			       bool hash)
+int ima_measure_critical_data(const char *event_label,
+			      const char *event_name,
+			      const void *buf, size_t buf_len,
+			      bool hash)
 {
 	if (!event_name || !event_label || !buf || !buf_len)
-		return;
+		return -ENOPARAM;
 
-	process_buffer_measurement(&init_user_ns, NULL, buf, buf_len, event_name,
-				   CRITICAL_DATA, 0, event_label,
-				   hash);
+	return process_buffer_measurement(&init_user_ns, NULL, buf, buf_len,
+					  event_name, CRITICAL_DATA, 0,
+					  event_label, hash);
 }
 
 static int __init init_ima(void)
diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
index 979ef6c71f3d..e3047ce64f39 100644
--- a/security/integrity/ima/ima_queue_keys.c
+++ b/security/integrity/ima/ima_queue_keys.c
@@ -134,6 +134,7 @@ void ima_process_queued_keys(void)
 {
 	struct ima_key_entry *entry, *tmp;
 	bool process = false;
+	int ret __maybe_unused;
 
 	if (ima_process_keys)
 		return;
@@ -159,13 +160,13 @@ void ima_process_queued_keys(void)
 
 	list_for_each_entry_safe(entry, tmp, &ima_keys, list) {
 		if (!timer_expired)
-			process_buffer_measurement(&init_user_ns, NULL,
-						   entry->payload,
-						   entry->payload_len,
-						   entry->keyring_name,
-						   KEY_CHECK, 0,
-						   entry->keyring_name,
-						   false);
+			ret = process_buffer_measurement(&init_user_ns, NULL,
+							 entry->payload,
+							 entry->payload_len,
+							 entry->keyring_name,
+							 KEY_CHECK, 0,
+							 entry->keyring_name,
+							 false);
 		list_del(&entry->list);
 		ima_free_key_entry(entry);
 	}
diff --git a/security/selinux/ima.c b/security/selinux/ima.c
index 34d421861bfc..4db9fa211638 100644
--- a/security/selinux/ima.c
+++ b/security/selinux/ima.c
@@ -75,6 +75,7 @@ void selinux_ima_measure_state_locked(struct selinux_state *state)
 	char *state_str = NULL;
 	void *policy = NULL;
 	size_t policy_len;
+	int measure_rc __maybe_unused;
 	int rc = 0;
 
 	WARN_ON(!mutex_is_locked(&state->policy_mutex));
@@ -85,8 +86,9 @@ void selinux_ima_measure_state_locked(struct selinux_state *state)
 		return;
 	}
 
-	ima_measure_critical_data("selinux", "selinux-state",
-				  state_str, strlen(state_str), false);
+	measure_rc = ima_measure_critical_data("selinux", "selinux-state",
+					       state_str, strlen(state_str),
+					       false);
 
 	kfree(state_str);
 
@@ -102,8 +104,8 @@ void selinux_ima_measure_state_locked(struct selinux_state *state)
 		return;
 	}
 
-	ima_measure_critical_data("selinux", "selinux-policy-hash",
-				  policy, policy_len, true);
+	measure_rc = ima_measure_critical_data("selinux", "selinux-policy-hash",
+					       policy, policy_len, true);
 
 	vfree(policy);
 }
-- 
2.25.1

[PATCH 3/3] ima: Add digest parameter to the functions to measure a buffer

[Roberto Sassu]

This patch adds the 'digest' parameter to ima_measure_critical_data() and
process_buffer_measurement(), so that callers can get the digest of the
passed buffer.

These functions calculate the digest even if there is no suitable rule in
the IMA policy and, in this case, they simply return 1 before generating a
new measurement entry.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
 include/linux/ima.h                          |  4 +--
 security/integrity/ima/ima.h                 |  2 +-
 security/integrity/ima/ima_appraise.c        |  2 +-
 security/integrity/ima/ima_asymmetric_keys.c |  2 +-
 security/integrity/ima/ima_init.c            |  2 +-
 security/integrity/ima/ima_main.c            | 31 +++++++++++++-------
 security/integrity/ima/ima_queue_keys.c      |  2 +-
 security/selinux/ima.c                       |  4 +--
 8 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 60492263aa64..7a1a1f97b4ea 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -38,7 +38,7 @@ extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size);
 extern int ima_measure_critical_data(const char *event_label,
 				     const char *event_name,
 				     const void *buf, size_t buf_len,
-				     bool hash);
+				     bool hash, u8 *digest);
 
 #ifdef CONFIG_IMA_APPRAISE_BOOTPARAM
 extern void ima_appraise_parse_cmdline(void);
@@ -147,7 +147,7 @@ static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {
 static inline int ima_measure_critical_data(const char *event_label,
 					     const char *event_name,
 					     const void *buf, size_t buf_len,
-					     bool hash)
+					     bool hash, u8 *digest)
 {
 	return -ENOENT;
 }
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 03db221324c3..ec803bafa6cc 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -268,7 +268,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
 			       struct inode *inode, const void *buf, int size,
 			       const char *eventname, enum ima_hooks func,
 			       int pcr, const char *func_data,
-			       bool buf_hash);
+			       bool buf_hash, u8 *digest);
 void ima_audit_measurement(struct integrity_iint_cache *iint,
 			   const unsigned char *filename);
 int ima_alloc_init_template(struct ima_event_data *event_data,
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 275a2377743f..05f3b1186a41 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -359,7 +359,7 @@ int ima_check_blacklist(struct integrity_iint_cache *iint,
 			process_rc = process_buffer_measurement(&init_user_ns,
 						   NULL, digest, digestsize,
 						   "blacklisted-hash", NONE,
-						   pcr, NULL, false);
+						   pcr, NULL, false, NULL);
 	}
 
 	return rc;
diff --git a/security/integrity/ima/ima_asymmetric_keys.c b/security/integrity/ima/ima_asymmetric_keys.c
index 910367cdd920..a0f7e2dbb9db 100644
--- a/security/integrity/ima/ima_asymmetric_keys.c
+++ b/security/integrity/ima/ima_asymmetric_keys.c
@@ -64,5 +64,5 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
 	ret = process_buffer_measurement(&init_user_ns, NULL,
 				   payload, payload_len,
 				   keyring->description, KEY_CHECK, 0,
-				   keyring->description, false);
+				   keyring->description, false, NULL);
 }
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index 6790eea88db8..0dd22e7752f5 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -156,7 +156,7 @@ int __init ima_init(void)
 
 	measure_rc = ima_measure_critical_data("kernel_info", "kernel_version",
 					       UTS_RELEASE, strlen(UTS_RELEASE),
-					       false);
+					       false, NULL);
 
 	return rc;
 }
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 45e048899b2f..a222e7f7b537 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -838,17 +838,19 @@ int ima_post_load_data(char *buf, loff_t size,
  * @pcr: pcr to extend the measurement
  * @func_data: func specific data, may be NULL
  * @buf_hash: measure buffer data hash
+ * @digest: buffer digest will be written to
  *
  * Based on policy, either the buffer data or buffer data hash is measured
  *
- * Returns 0 if the buffer has been successfully measured, a negative value
- * otherwise.
+ * Returns 0 if the buffer has been successfully measured, 1 if the digest
+ * has been written to the passed location but not added to a measurement entry,
+ * a negative value otherwise.
  */
 int process_buffer_measurement(struct user_namespace *mnt_userns,
 			       struct inode *inode, const void *buf, int size,
 			       const char *eventname, enum ima_hooks func,
 			       int pcr, const char *func_data,
-			       bool buf_hash)
+			       bool buf_hash, u8 *digest)
 {
 	int ret = 0;
 	const char *audit_cause = "ENOMEM";
@@ -869,7 +871,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
 	int action = 0;
 	u32 secid;
 
-	if (!ima_policy_flag)
+	if (!ima_policy_flag && !digest)
 		return -ENOENT;
 
 	template = ima_template_desc_buf();
@@ -891,7 +893,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
 		action = ima_get_action(mnt_userns, inode, current_cred(),
 					secid, 0, func, &pcr, &template,
 					func_data);
-		if (!(action & IMA_MEASURE))
+		if (!(action & IMA_MEASURE) && !digest)
 			return -ENOENT;
 	}
 
@@ -922,6 +924,13 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
 		event_data.buf_len = digest_hash_len;
 	}
 
+	if (digest)
+		memcpy(digest, iint.ima_hash->digest,
+		       hash_digest_size[ima_hash_algo]);
+
+	if (!ima_policy_flag || (func && !(action & IMA_MEASURE)))
+		return 1;
+
 	ret = ima_alloc_init_template(&event_data, &entry, template);
 	if (ret < 0) {
 		audit_cause = "alloc_entry";
@@ -966,7 +975,7 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
 	ret = process_buffer_measurement(file_mnt_user_ns(f.file),
 					 file_inode(f.file), buf, size,
 					 "kexec-cmdline", KEXEC_CMDLINE, 0,
-					 NULL, false);
+					 NULL, false, NULL);
 	fdput(f);
 }
 
@@ -977,26 +986,28 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
  * @buf: pointer to buffer data
  * @buf_len: length of buffer data (in bytes)
  * @hash: measure buffer data hash
+ * @digest: buffer digest will be written to
  *
  * Measure data critical to the integrity of the kernel into the IMA log
  * and extend the pcr.  Examples of critical data could be various data
  * structures, policies, and states stored in kernel memory that can
  * impact the integrity of the system.
  *
- * Returns 0 if the buffer has been successfully measured, a negative value
- * otherwise.
+ * Returns 0 if the buffer has been successfully measured, 1 if the digest
+ * has been written to the passed location but not added to a measurement entry,
+ * a negative value otherwise.
  */
 int ima_measure_critical_data(const char *event_label,
 			      const char *event_name,
 			      const void *buf, size_t buf_len,
-			      bool hash)
+			      bool hash, u8 *digest)
 {
 	if (!event_name || !event_label || !buf || !buf_len)
 		return -ENOPARAM;
 
 	return process_buffer_measurement(&init_user_ns, NULL, buf, buf_len,
 					  event_name, CRITICAL_DATA, 0,
-					  event_label, hash);
+					  event_label, hash, digest);
 }
 
 static int __init init_ima(void)
diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
index e3047ce64f39..ac00a4778a91 100644
--- a/security/integrity/ima/ima_queue_keys.c
+++ b/security/integrity/ima/ima_queue_keys.c
@@ -166,7 +166,7 @@ void ima_process_queued_keys(void)
 							 entry->keyring_name,
 							 KEY_CHECK, 0,
 							 entry->keyring_name,
-							 false);
+							 false, NULL);
 		list_del(&entry->list);
 		ima_free_key_entry(entry);
 	}
diff --git a/security/selinux/ima.c b/security/selinux/ima.c
index 4db9fa211638..96bd7ead8081 100644
--- a/security/selinux/ima.c
+++ b/security/selinux/ima.c
@@ -88,7 +88,7 @@ void selinux_ima_measure_state_locked(struct selinux_state *state)
 
 	measure_rc = ima_measure_critical_data("selinux", "selinux-state",
 					       state_str, strlen(state_str),
-					       false);
+					       false, NULL);
 
 	kfree(state_str);
 
@@ -105,7 +105,7 @@ void selinux_ima_measure_state_locked(struct selinux_state *state)
 	}
 
 	measure_rc = ima_measure_critical_data("selinux", "selinux-policy-hash",
-					       policy, policy_len, true);
+					       policy, policy_len, true, NULL);
 
 	vfree(policy);
 }
-- 
2.25.1

Re: [PATCH 3/3] ima: Add digest parameter to the functions to measure a buffer

[Lakshmi Ramasubramanian]

On 6/30/2021 7:16 AM, Roberto Sassu wrote:

Hi Roberto,

> This patch adds the 'digest' parameter to ima_measure_critical_data() and
> process_buffer_measurement(), so that callers can get the digest of the
> passed buffer.
> 
> These functions calculate the digest even if there is no suitable rule in
> the IMA policy and, in this case, they simply return 1 before generating a
> new measurement entry.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
>   include/linux/ima.h                          |  4 +--
>   security/integrity/ima/ima.h                 |  2 +-
>   security/integrity/ima/ima_appraise.c        |  2 +-
>   security/integrity/ima/ima_asymmetric_keys.c |  2 +-
>   security/integrity/ima/ima_init.c            |  2 +-
>   security/integrity/ima/ima_main.c            | 31 +++++++++++++-------
>   security/integrity/ima/ima_queue_keys.c      |  2 +-
>   security/selinux/ima.c                       |  4 +--
>   8 files changed, 30 insertions(+), 19 deletions(-)
> 

>   
> +	if (digest)
> +		memcpy(digest, iint.ima_hash->digest,
> +		       hash_digest_size[ima_hash_algo]);

I think the caller should also pass the size of the buffer allocated to 
receive the calculated digest. And, here copy only up to that many bytes 
so we don't accidentally cause buffer overrun.

  -lakshmi

> +
> +	if (!ima_policy_flag || (func && !(action & IMA_MEASURE)))
> +		return 1;
> +
>   	ret = ima_alloc_init_template(&event_data, &entry, template);
>   	if (ret < 0) {
>   		audit_cause = "alloc_entry";
> @@ -966,7 +975,7 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
>   	ret = process_buffer_measurement(file_mnt_user_ns(f.file),
>   					 file_inode(f.file), buf, size,
>   					 "kexec-cmdline", KEXEC_CMDLINE, 0,
> -					 NULL, false);
> +					 NULL, false, NULL);
>   	fdput(f);
>   }
>   
> @@ -977,26 +986,28 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
>    * @buf: pointer to buffer data
>    * @buf_len: length of buffer data (in bytes)
>    * @hash: measure buffer data hash
> + * @digest: buffer digest will be written to
>    *
>    * Measure data critical to the integrity of the kernel into the IMA log
>    * and extend the pcr.  Examples of critical data could be various data
>    * structures, policies, and states stored in kernel memory that can
>    * impact the integrity of the system.
>    *
> - * Returns 0 if the buffer has been successfully measured, a negative value
> - * otherwise.
> + * Returns 0 if the buffer has been successfully measured, 1 if the digest
> + * has been written to the passed location but not added to a measurement entry,
> + * a negative value otherwise.
>    */
>   int ima_measure_critical_data(const char *event_label,
>   			      const char *event_name,
>   			      const void *buf, size_t buf_len,
> -			      bool hash)
> +			      bool hash, u8 *digest)
>   {
>   	if (!event_name || !event_label || !buf || !buf_len)
>   		return -ENOPARAM;
>   
>   	return process_buffer_measurement(&init_user_ns, NULL, buf, buf_len,
>   					  event_name, CRITICAL_DATA, 0,
> -					  event_label, hash);
> +					  event_label, hash, digest);
>   }
>   
>   static int __init init_ima(void)
> diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
> index e3047ce64f39..ac00a4778a91 100644
> --- a/security/integrity/ima/ima_queue_keys.c
> +++ b/security/integrity/ima/ima_queue_keys.c
> @@ -166,7 +166,7 @@ void ima_process_queued_keys(void)
>   							 entry->keyring_name,
>   							 KEY_CHECK, 0,
>   							 entry->keyring_name,
> -							 false);
> +							 false, NULL);
>   		list_del(&entry->list);
>   		ima_free_key_entry(entry);
>   	}
> diff --git a/security/selinux/ima.c b/security/selinux/ima.c
> index 4db9fa211638..96bd7ead8081 100644
> --- a/security/selinux/ima.c
> +++ b/security/selinux/ima.c
> @@ -88,7 +88,7 @@ void selinux_ima_measure_state_locked(struct selinux_state *state)
>   
>   	measure_rc = ima_measure_critical_data("selinux", "selinux-state",
>   					       state_str, strlen(state_str),
> -					       false);
> +					       false, NULL);
>   
>   	kfree(state_str);
>   
> @@ -105,7 +105,7 @@ void selinux_ima_measure_state_locked(struct selinux_state *state)
>   	}
>   
>   	measure_rc = ima_measure_critical_data("selinux", "selinux-policy-hash",
> -					       policy, policy_len, true);
> +					       policy, policy_len, true, NULL);
>   
>   	vfree(policy);
>   }
> 

RE: [PATCH 3/3] ima: Add digest parameter to the functions to measure a buffer

[Roberto Sassu]

> From: Lakshmi Ramasubramanian [mailto:nramas@linux.microsoft.com]
> Sent: Wednesday, June 30, 2021 4:56 PM
> On 6/30/2021 7:16 AM, Roberto Sassu wrote:
> 
> Hi Roberto,
> 
> > This patch adds the 'digest' parameter to ima_measure_critical_data() and
> > process_buffer_measurement(), so that callers can get the digest of the
> > passed buffer.
> >
> > These functions calculate the digest even if there is no suitable rule in
> > the IMA policy and, in this case, they simply return 1 before generating a
> > new measurement entry.
> >
> > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> > ---
> >   include/linux/ima.h                          |  4 +--
> >   security/integrity/ima/ima.h                 |  2 +-
> >   security/integrity/ima/ima_appraise.c        |  2 +-
> >   security/integrity/ima/ima_asymmetric_keys.c |  2 +-
> >   security/integrity/ima/ima_init.c            |  2 +-
> >   security/integrity/ima/ima_main.c            | 31 +++++++++++++-------
> >   security/integrity/ima/ima_queue_keys.c      |  2 +-
> >   security/selinux/ima.c                       |  4 +--
> >   8 files changed, 30 insertions(+), 19 deletions(-)
> >
> 
> >
> > +	if (digest)
> > +		memcpy(digest, iint.ima_hash->digest,
> > +		       hash_digest_size[ima_hash_algo]);
> 
> I think the caller should also pass the size of the buffer allocated to
> receive the calculated digest. And, here copy only up to that many bytes
> so we don't accidentally cause buffer overrun.

Hi Lakshmi

yes, I agree. I will add it in the next version of the patch set.

Thanks

Roberto

HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Li Peng, Li Jian, Shi Yanli

>   -lakshmi
> 
> > +
> > +	if (!ima_policy_flag || (func && !(action & IMA_MEASURE)))
> > +		return 1;
> > +
> >   	ret = ima_alloc_init_template(&event_data, &entry, template);
> >   	if (ret < 0) {
> >   		audit_cause = "alloc_entry";
> > @@ -966,7 +975,7 @@ void ima_kexec_cmdline(int kernel_fd, const void
> *buf, int size)
> >   	ret = process_buffer_measurement(file_mnt_user_ns(f.file),
> >   					 file_inode(f.file), buf, size,
> >   					 "kexec-cmdline", KEXEC_CMDLINE, 0,
> > -					 NULL, false);
> > +					 NULL, false, NULL);
> >   	fdput(f);
> >   }
> >
> > @@ -977,26 +986,28 @@ void ima_kexec_cmdline(int kernel_fd, const void
> *buf, int size)
> >    * @buf: pointer to buffer data
> >    * @buf_len: length of buffer data (in bytes)
> >    * @hash: measure buffer data hash
> > + * @digest: buffer digest will be written to
> >    *
> >    * Measure data critical to the integrity of the kernel into the IMA log
> >    * and extend the pcr.  Examples of critical data could be various data
> >    * structures, policies, and states stored in kernel memory that can
> >    * impact the integrity of the system.
> >    *
> > - * Returns 0 if the buffer has been successfully measured, a negative value
> > - * otherwise.
> > + * Returns 0 if the buffer has been successfully measured, 1 if the digest
> > + * has been written to the passed location but not added to a measurement
> entry,
> > + * a negative value otherwise.
> >    */
> >   int ima_measure_critical_data(const char *event_label,
> >   			      const char *event_name,
> >   			      const void *buf, size_t buf_len,
> > -			      bool hash)
> > +			      bool hash, u8 *digest)
> >   {
> >   	if (!event_name || !event_label || !buf || !buf_len)
> >   		return -ENOPARAM;
> >
> >   	return process_buffer_measurement(&init_user_ns, NULL, buf,
> buf_len,
> >   					  event_name, CRITICAL_DATA, 0,
> > -					  event_label, hash);
> > +					  event_label, hash, digest);
> >   }
> >
> >   static int __init init_ima(void)
> > diff --git a/security/integrity/ima/ima_queue_keys.c
> b/security/integrity/ima/ima_queue_keys.c
> > index e3047ce64f39..ac00a4778a91 100644
> > --- a/security/integrity/ima/ima_queue_keys.c
> > +++ b/security/integrity/ima/ima_queue_keys.c
> > @@ -166,7 +166,7 @@ void ima_process_queued_keys(void)
> >   							 entry-
> >keyring_name,
> >   							 KEY_CHECK, 0,
> >   							 entry-
> >keyring_name,
> > -							 false);
> > +							 false, NULL);
> >   		list_del(&entry->list);
> >   		ima_free_key_entry(entry);
> >   	}
> > diff --git a/security/selinux/ima.c b/security/selinux/ima.c
> > index 4db9fa211638..96bd7ead8081 100644
> > --- a/security/selinux/ima.c
> > +++ b/security/selinux/ima.c
> > @@ -88,7 +88,7 @@ void selinux_ima_measure_state_locked(struct
> selinux_state *state)
> >
> >   	measure_rc = ima_measure_critical_data("selinux", "selinux-state",
> >   					       state_str, strlen(state_str),
> > -					       false);
> > +					       false, NULL);
> >
> >   	kfree(state_str);
> >
> > @@ -105,7 +105,7 @@ void selinux_ima_measure_state_locked(struct
> selinux_state *state)
> >   	}
> >
> >   	measure_rc = ima_measure_critical_data("selinux", "selinux-policy-
> hash",
> > -					       policy, policy_len, true);
> > +					       policy, policy_len, true, NULL);
> >
> >   	vfree(policy);
> >   }
> >