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integrity: Add errno field in audit message

PATCH In review Lakshmi Ramasubramanian 3 participants 8 messages Jun 18, 2020 – Jun 29, 2020

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#0 lore raw

PATCH v3 1/2 integrity: Add errno field in audit message

Error code is not included in the audit messages logged by the integrity subsystem.

Define a new function integrity_audit_message() that takes error code in the "errno" parameter. Add "errno" field in the audit messages logged by the integrity subsystem and set the value passed in the "errno" parameter.

[    6.303048] audit: type=1804 audit(1592506281.627:2): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=kernel op=measuring_key cause=ENOMEM comm="swapper/0" name=".builtin_trusted_keys" res=0 errno=-12
[    7.987647] audit: type=1802 audit(1592506283.312:9): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 op=policy_update cause=completed comm="systemd" res=1 errno=0
[    8.019432] audit: type=1804 audit(1592506283.344:10): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 op=measuring_kexec_cmdline cause=hashing_error comm="systemd" name="kexec-cmdline" res=0 errno=-22
---
 security/integrity/integrity.h       | 13 +++++++++++++
 security/integrity/integrity_audit.c | 11 ++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)
security/integrity/integrity.h +13 -0
index 16c1894c29bb..413c803c5208 100644
@@ -239,6 +239,11 @@ void integrity_audit_msg(int audit_msgno, struct inode *inode,
 			 const unsigned char *fname, const char *op,
 			 const char *cause, int result, int info);
 
+void integrity_audit_message(int audit_msgno, struct inode *inode,
+			     const unsigned char *fname, const char *op,
+			     const char *cause, int result, int info,
+			     int errno);
+
 static inline struct audit_buffer *
 integrity_audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, int type)
 {
@@ -253,6 +258,14 @@ static inline void integrity_audit_msg(int audit_msgno, struct inode *inode,
 {
 }
 
+static inline void integrity_audit_message(int audit_msgno,
+					   struct inode *inode,
+					   const unsigned char *fname,
+					   const char *op, const char *cause,
+					   int result, int info, int errno)
+{
+}
+
 static inline struct audit_buffer *
 integrity_audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, int type)
 {
security/integrity/integrity_audit.c +10 -1
index 5109173839cc..f25e7df099c8 100644
@@ -28,6 +28,15 @@ __setup("integrity_audit=", integrity_audit_setup);
 void integrity_audit_msg(int audit_msgno, struct inode *inode,
 			 const unsigned char *fname, const char *op,
 			 const char *cause, int result, int audit_info)
+{
+	integrity_audit_message(audit_msgno, inode, fname, op, cause,
+				result, audit_info, 0);
+}
+
+void integrity_audit_message(int audit_msgno, struct inode *inode,
+			     const unsigned char *fname, const char *op,
+			     const char *cause, int result, int audit_info,
+			     int errno)
 {
 	struct audit_buffer *ab;
 	char name[TASK_COMM_LEN];
@@ -53,6 +62,6 @@ void integrity_audit_msg(int audit_msgno, struct inode *inode,
 		audit_log_untrustedstring(ab, inode->i_sb->s_id);
 		audit_log_format(ab, " ino=%lu", inode->i_ino);
 	}
-	audit_log_format(ab, " res=%d", !result);
+	audit_log_format(ab, " res=%d errno=%d", !result, errno);
 	audit_log_end(ab);
 }
Signature · 1 line
2.27.0
#1 lore raw

PATCH v3 2/2 IMA: Add audit log for failure conditions

process_buffer_measurement() and ima_alloc_key_entry() functions need to log an audit message for auditing integrity measurement failures.

Add audit message in these two functions. Remove "pr_devel" log message in process_buffer_measurement().

Sample audit messages:

[    6.303048] audit: type=1804 audit(1592506281.627:2): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=kernel op=measuring_key cause=ENOMEM comm="swapper/0" name=".builtin_trusted_keys" res=0 errno=-12
[    8.019432] audit: type=1804 audit(1592506283.344:10): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 op=measuring_kexec_cmdline cause=hashing_error comm="systemd" name="kexec-cmdline" res=0 errno=-22
---
 security/integrity/ima/ima.h            | 48 ++++++++++++++++---------
 security/integrity/ima/ima_main.c       | 18 +++++++---
 security/integrity/ima/ima_policy.c     |  2 +-
 security/integrity/ima/ima_queue_keys.c |  5 +++
 4 files changed, 51 insertions(+), 22 deletions(-)
security/integrity/ima/ima.h +32 -16
index df93ac258e01..c3a32e181b48 100644
@@ -186,27 +186,43 @@ static inline unsigned int ima_hash_key(u8 *digest)
 	return (digest[0] | digest[1] << 8) % IMA_MEASURE_HTABLE_SIZE;
 }
 
-#define __ima_hooks(hook)		\
-	hook(NONE)			\
-	hook(FILE_CHECK)		\
-	hook(MMAP_CHECK)		\
-	hook(BPRM_CHECK)		\
-	hook(CREDS_CHECK)		\
-	hook(POST_SETATTR)		\
-	hook(MODULE_CHECK)		\
-	hook(FIRMWARE_CHECK)		\
-	hook(KEXEC_KERNEL_CHECK)	\
-	hook(KEXEC_INITRAMFS_CHECK)	\
-	hook(POLICY_CHECK)		\
-	hook(KEXEC_CMDLINE)		\
-	hook(KEY_CHECK)			\
-	hook(MAX_CHECK)
-#define __ima_hook_enumify(ENUM)	ENUM,
+#define __ima_hooks(hook)				\
+	hook(NONE, none)				\
+	hook(FILE_CHECK, file)				\
+	hook(MMAP_CHECK, mmap)				\
+	hook(BPRM_CHECK, bprm)				\
+	hook(CREDS_CHECK, creds)			\
+	hook(POST_SETATTR, post_setattr)		\
+	hook(MODULE_CHECK, module)			\
+	hook(FIRMWARE_CHECK, firmware)			\
+	hook(KEXEC_KERNEL_CHECK, kexec_kernel)		\
+	hook(KEXEC_INITRAMFS_CHECK, kexec_initramfs)	\
+	hook(POLICY_CHECK, policy)			\
+	hook(KEXEC_CMDLINE, kexec_cmdline)		\
+	hook(KEY_CHECK, key)				\
+	hook(MAX_CHECK, none)
+
+#define __ima_hook_enumify(ENUM, str)	ENUM,
+#define __ima_stringify(arg) (#arg)
+#define __ima_hook_measuring_stringify(ENUM, str) \
+		(__ima_stringify(measuring_ ##str)),
 
 enum ima_hooks {
 	__ima_hooks(__ima_hook_enumify)
 };
 
+static const char * const ima_hooks_measure_str[] = {
+	__ima_hooks(__ima_hook_measuring_stringify)
+};
+
+static inline const char *func_measure_str(enum ima_hooks func)
+{
+	if (func >= MAX_CHECK)
+		return ima_hooks_measure_str[NONE];
+
+	return ima_hooks_measure_str[func];
+}
+
 extern const char *const func_tokens[];
 
 struct modsig;
security/integrity/ima/ima_main.c +13 -5
index c1583d98c5e5..8351b2fd48e0 100644
@@ -740,6 +740,7 @@ void process_buffer_measurement(const void *buf, int size,
 				int pcr, const char *keyring)
 {
 	int ret = 0;
+	const char *audit_cause = "ENOMEM";
 	struct ima_template_entry *entry = NULL;
 	struct integrity_iint_cache iint = {};
 	struct ima_event_data event_data = {.iint = &iint,
@@ -794,21 +795,28 @@ void process_buffer_measurement(const void *buf, int size,
 	iint.ima_hash->length = hash_digest_size[ima_hash_algo];
 
 	ret = ima_calc_buffer_hash(buf, size, iint.ima_hash);
-	if (ret < 0)
+	if (ret < 0) {
+		audit_cause = "hashing_error";
 		goto out;
+	}
 
 	ret = ima_alloc_init_template(&event_data, &entry, template);
-	if (ret < 0)
+	if (ret < 0) {
+		audit_cause = "alloc_entry";
 		goto out;
+	}
 
 	ret = ima_store_template(entry, violation, NULL, buf, pcr);
-
-	if (ret < 0)
+	if (ret < 0) {
+		audit_cause = "store_entry";
 		ima_free_template_entry(entry);
+	}
 
 out:
 	if (ret < 0)
-		pr_devel("%s: failed, result: %d\n", __func__, ret);
+		integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL, eventname,
+					func_measure_str(func),
+					audit_cause, ret, 0, ret);
 
 	return;
 }
security/integrity/ima/ima_policy.c +1 -1
index e493063a3c34..66aa3e17a888 100644
@@ -1414,7 +1414,7 @@ void ima_delete_rules(void)
 	}
 }
 
-#define __ima_hook_stringify(str)	(#str),
+#define __ima_hook_stringify(func, str)	(#func),
 
 const char *const func_tokens[] = {
 	__ima_hooks(__ima_hook_stringify)
security/integrity/ima/ima_queue_keys.c +5 -0
index cb3e3f501593..56ce24a18b66 100644
@@ -68,6 +68,7 @@ static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
 						 size_t payload_len)
 {
 	int rc = 0;
+	const char *audit_cause = "ENOMEM";
 	struct ima_key_entry *entry;
 
 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
@@ -88,6 +89,10 @@ static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
 
 out:
 	if (rc) {
+		integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL,
+					keyring->description,
+					func_measure_str(KEY_CHECK),
+					audit_cause, rc, 0, rc);
 		ima_free_key_entry(entry);
 		entry = NULL;
 	}
Signature · 1 line
2.27.0
maintainer Reviewed-by on v3 2/2
#2 lore raw

Re: [PATCH v3 2/2] IMA: Add audit log for failure conditions

Quoted 6 lines · Lakshmi Ramasubramanian

process_buffer_measurement() and ima_alloc_key_entry() functions need to log an audit message for auditing integrity measurement failures.

Add audit message in these two functions. Remove "pr_devel" log message in process_buffer_measurement().

Quoted 6 lines

Sample audit messages:

[    6.303048] audit: type=1804 audit(1592506281.627:2): pid=1 uid=0

auid=4294967295 ses=4294967295 subj=kernel op=measuring_key cause=ENOMEM comm="swapper/0" name=".builtin_trusted_keys" res=0 errno=-12

My only concern is that auditing -ENOMEM will put additional memory pressure on the system.  I'm not sure if this is a concern and, if so, how it should be handled.

Quoted 8 lines
[    8.019432] audit: type=1804 audit(1592506283.344:10): pid=1

uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 op=measuring_kexec_cmdline cause=hashing_error comm="systemd" name="kexec-cmdline" res=0 errno=-22

#3 lore raw

Re: [PATCH v3 2/2] IMA: Add audit log for failure conditions

On 6/23/20 12:58 PM, Mimi Zohar wrote:

Hi Steve\Paul,

Quoted 10 lines
Quoted 6 lines

Sample audit messages:

[    6.303048] audit: type=1804 audit(1592506281.627:2): pid=1 uid=0

auid=4294967295 ses=4294967295 subj=kernel op=measuring_key cause=ENOMEM comm="swapper/0" name=".builtin_trusted_keys" res=0 errno=-12

My only concern is that auditing -ENOMEM will put additional memory pressure on the system.  I'm not sure if this is a concern and, if so, how it should be handled.

Do you have any concerns with respect to adding audit messages in low memory conditions?

Quoted 2 lines

Thanks Mimi

-lakshmi

maintainer
#4 lore raw

Re: [PATCH v3 2/2] IMA: Add audit log for failure conditions

Quoted 12 lines · Lakshmi Ramasubramanian

On 6/23/20 12:58 PM, Mimi Zohar wrote:

Hi Steve\Paul,

Quoted 7 lines
Quoted 6 lines

Sample audit messages:

[    6.303048] audit: type=1804 audit(1592506281.627:2): pid=1 uid=0

auid=4294967295 ses=4294967295 subj=kernel op=measuring_key cause=ENOMEM comm="swapper/0" name=".builtin_trusted_keys" res=0 errno=-12

Quoted 6 lines
Quoted 3 lines

My only concern is that auditing -ENOMEM will put additional memory pressure on the system. I'm not sure if this is a concern and, if so, how it should be handled.

Do you have any concerns with respect to adding audit messages in low memory conditions?

Assuming the system is not completely toast, the allocation failure could be a very transient issue; I wouldn't worry too much about it.

Signature · 2 lines
paul moore
www.paul-moore.com
maintainer
#5 lore raw

Re: [PATCH v3 2/2] IMA: Add audit log for failure conditions

Quoted 18 lines · Paul Moore
Quoted 16 lines · Lakshmi Ramasubramanian

On 6/23/20 12:58 PM, Mimi Zohar wrote:

Hi Steve\Paul,

Quoted 10 lines
Quoted 6 lines

Sample audit messages:

[    6.303048] audit: type=1804 audit(1592506281.627:2): pid=1 uid=0

auid=4294967295 ses=4294967295 subj=kernel op=measuring_key cause=ENOMEM comm="swapper/0" name=".builtin_trusted_keys" res=0 errno=-12

My only concern is that auditing -ENOMEM will put additional memory pressure on the system. I'm not sure if this is a concern and, if so, how it should be handled.

Quoted 5 lines
Quoted 2 lines

Do you have any concerns with respect to adding audit messages in low memory conditions?

Assuming the system is not completely toast, the allocation failure could be a very transient issue; I wouldn't worry too much about it.

There was a major clean up of removing ENOMEM error messages through out the kernel a while ago by Wolfram Sang.  The subject lines included "don't print error when allocating XXX fails".  As it turns out, they were being removed because "kmalloc will print enough information in case of failure."  It had nothing to do with memory pressure on the system.

Thanks, Paul.  I think we're good.

Mimi

--
Linux-audit mailing list
[email protected]
https://www.redhat.com/mailman/listinfo/linux-audit

maintainer
#6 lore raw
In reply to Lakshmi Ramasubramanian
Quoted 10 lines · Lakshmi Ramasubramanian

Error code is not included in the audit messages logged by the integrity subsystem.

Define a new function integrity_audit_message() that takes error code in the "errno" parameter. Add "errno" field in the audit messages logged by the integrity subsystem and set the value passed in the "errno" parameter.

[    6.303048] audit: type=1804 audit(1592506281.627:2): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=kernel op=measuring_key cause=ENOMEM comm="swapper/0" name=".builtin_trusted_keys" res=0 errno=-12
Quoted 7 lines
[    7.987647] audit: type=1802 audit(1592506283.312:9): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 op=policy_update cause=completed comm="systemd" res=1 errno=0
[    8.019432] audit: type=1804 audit(1592506283.344:10): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 op=measuring_kexec_cmdline cause=hashing_error comm="systemd" name="kexec-cmdline" res=0 errno=-22

Thanks, Lakshmi.  Steve, Paul, because of the code changes, your tags were dropped.

Mimi

maintainer Acked-by on v3 1/2
#7 lore raw
In reply to Lakshmi Ramasubramanian
Quoted 15 lines · Lakshmi Ramasubramanian

Error code is not included in the audit messages logged by the integrity subsystem.

Define a new function integrity_audit_message() that takes error code in the "errno" parameter. Add "errno" field in the audit messages logged by the integrity subsystem and set the value passed in the "errno" parameter.

[    6.303048] audit: type=1804 audit(1592506281.627:2): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=kernel op=measuring_key cause=ENOMEM comm="swapper/0" name=".builtin_trusted_keys" res=0 errno=-12
[    7.987647] audit: type=1802 audit(1592506283.312:9): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 op=policy_update cause=completed comm="systemd" res=1 errno=0
[    8.019432] audit: type=1804 audit(1592506283.344:10): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 op=measuring_kexec_cmdline cause=hashing_error comm="systemd" name="kexec-cmdline" res=0 errno=-22
Quoted 7 lines
---
 security/integrity/integrity.h       | 13 +++++++++++++
 security/integrity/integrity_audit.c | 11 ++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

The audit record changes look good to me.

Quoted 62 lines
security/integrity/integrity.h +13 -0
index 16c1894c29bb..413c803c5208 100644
@@ -239,6 +239,11 @@ void integrity_audit_msg(int audit_msgno, struct inode *inode,
                         const unsigned char *fname, const char *op,
                         const char *cause, int result, int info);
 
+void integrity_audit_message(int audit_msgno, struct inode *inode,
+                            const unsigned char *fname, const char *op,
+                            const char *cause, int result, int info,
+                            int errno);
+
 static inline struct audit_buffer *
 integrity_audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, int type)
 {
@@ -253,6 +258,14 @@ static inline void integrity_audit_msg(int audit_msgno, struct inode *inode,
 {
 }
 
+static inline void integrity_audit_message(int audit_msgno,
+                                          struct inode *inode,
+                                          const unsigned char *fname,
+                                          const char *op, const char *cause,
+                                          int result, int info, int errno)
+{
+}
+
 static inline struct audit_buffer *
 integrity_audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, int type)
 {
security/integrity/integrity_audit.c +10 -2
index 5109173839cc..f25e7df099c8 100644
@@ -28,6 +28,15 @@ __setup("integrity_audit=", integrity_audit_setup);
 void integrity_audit_msg(int audit_msgno, struct inode *inode,
                         const unsigned char *fname, const char *op,
                         const char *cause, int result, int audit_info)
+{
+       integrity_audit_message(audit_msgno, inode, fname, op, cause,
+                               result, audit_info, 0);
+}
+
+void integrity_audit_message(int audit_msgno, struct inode *inode,
+                            const unsigned char *fname, const char *op,
+                            const char *cause, int result, int audit_info,
+                            int errno)
 {
        struct audit_buffer *ab;
        char name[TASK_COMM_LEN];
@@ -53,6 +62,6 @@ void integrity_audit_msg(int audit_msgno, struct inode *inode,
                audit_log_untrustedstring(ab, inode->i_sb->s_id);
                audit_log_format(ab, " ino=%lu", inode->i_ino);
        }
-       audit_log_format(ab, " res=%d", !result);
+       audit_log_format(ab, " res=%d errno=%d", !result, errno);
        audit_log_end(ab);
 }
--

2.27.0

Signature · 2 lines
paul moore
www.paul-moore.com