[PATCH v5 0/5] Audit: Records for multiple security contexts

[PATCH v5 0/5] Audit: Records for multiple security contexts

[Casey Schaufler]

The Linux audit system includes LSM based security "context" information
in its events. Historically, only one LSM that uses security contexts can
be active on a system. One of the few obsticles to allowing multiple LSM
support is the inability to report more than one security context in an
audit event. This patchset provides a mechanism to provide supplimental
records containing more than one security context for subjects and
objects.

The mechanism for reporting multiple security contexts inspired
considerable discussion. It would have been possible to add multiple
contexts to existing records using sophisticated formatting. This would
have significant backward compatibility issues, and require additional
parsing in user space code. Adding new records for an event that contain
the contexts is more in keeping with the way audit events have been
constructed in the past.

Only audit events associated with system calls have required multiple
records prior to this. Mechanism has been added allowing any event
to be composed of multiple records. This should make it easier to
add information to existing audit events without breaking backward
compatability.

v5:
Comment on the LSM_ID_UNDEF behavior in security_secid_to_secctx().
Change some names to better reflect their purpose.
Move alignment changes into a separate patch.
v4:
Use LSM_ID_UNDEF when checking for valid LSM IDs in
security_lsmprop_to_secctx().
Fix the object record to include only those for LSMs that use them.
Squash the two patches dealing with subject contexts.
Base the patches on Paul Moore's LSM initialization patchset.
https://lore.kernel.org/all/20250409185019.238841-31-paul@paul-moore.com/
v3:
Rework how security modules identify that they provide security
contexts to the audit system. Maintain a list within the audit
system of the security modules that provide security contexts.
Revert the separate counts of subject and object contexts.
v2:
Maintain separate counts for LSMs using subject contexts and object
contexts. AppArmor uses the former but not the latter.
Correct error handling in object record creation.

https://github.com/cschaufler/lsm-stacking#audit-6.16-rc4-v5

Casey Schaufler (5):
  Audit: Create audit_stamp structure
  LSM: security_lsmblob_to_secctx module selection
  Audit: Add record for multiple task security contexts
  Audit: Fix indentation in audit_log_exit
  Audit: Add record for multiple object contexts

 include/linux/audit.h        |  23 +++
 include/linux/security.h     |   6 +-
 include/uapi/linux/audit.h   |   2 +
 kernel/audit.c               | 274 ++++++++++++++++++++++++++++++-----
 kernel/audit.h               |  13 +-
 kernel/auditsc.c             |  65 +++------
 net/netlabel/netlabel_user.c |   8 +-
 security/apparmor/lsm.c      |   3 +
 security/lsm.h               |   4 -
 security/lsm_init.c          |   5 -
 security/security.c          |  21 ++-
 security/selinux/hooks.c     |   5 +
 security/smack/smack_lsm.c   |   5 +
 13 files changed, 325 insertions(+), 109 deletions(-)

-- 
2.50.1

[PATCH v5 1/5] Audit: Create audit_stamp structure

[Casey Schaufler]

Replace the timestamp and serial number pair used in audit records
with a structure containing the two elements.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 kernel/audit.c   | 17 +++++++++--------
 kernel/audit.h   | 13 +++++++++----
 kernel/auditsc.c | 22 +++++++++-------------
 3 files changed, 27 insertions(+), 25 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index 61b5744d0bb6..547967cb4266 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1833,11 +1833,11 @@ unsigned int audit_serial(void)
 }
 
 static inline void audit_get_stamp(struct audit_context *ctx,
-				   struct timespec64 *t, unsigned int *serial)
+				   struct audit_stamp *stamp)
 {
-	if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
-		ktime_get_coarse_real_ts64(t);
-		*serial = audit_serial();
+	if (!ctx || !auditsc_get_stamp(ctx, stamp)) {
+		ktime_get_coarse_real_ts64(&stamp->ctime);
+		stamp->serial = audit_serial();
 	}
 }
 
@@ -1860,8 +1860,7 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 				     int type)
 {
 	struct audit_buffer *ab;
-	struct timespec64 t;
-	unsigned int serial;
+	struct audit_stamp stamp;
 
 	if (audit_initialized != AUDIT_INITIALIZED)
 		return NULL;
@@ -1916,12 +1915,14 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 		return NULL;
 	}
 
-	audit_get_stamp(ab->ctx, &t, &serial);
+	audit_get_stamp(ab->ctx, &stamp);
 	/* cancel dummy context to enable supporting records */
 	if (ctx)
 		ctx->dummy = 0;
 	audit_log_format(ab, "audit(%llu.%03lu:%u): ",
-			 (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
+			 (unsigned long long)stamp.ctime.tv_sec,
+			 stamp.ctime.tv_nsec/1000000,
+			 stamp.serial);
 
 	return ab;
 }
diff --git a/kernel/audit.h b/kernel/audit.h
index 0211cb307d30..4d6dd2588f9b 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -99,6 +99,12 @@ struct audit_proctitle {
 	char	*value;	/* the cmdline field */
 };
 
+/* A timestamp/serial pair to identify an event */
+struct audit_stamp {
+	struct timespec64	ctime;	/* time of syscall entry */
+	unsigned int		serial;	/* serial number for record */
+};
+
 /* The per-task audit context. */
 struct audit_context {
 	int		    dummy;	/* must be the first element */
@@ -108,10 +114,9 @@ struct audit_context {
 		AUDIT_CTX_URING,	/* in use by io_uring */
 	} context;
 	enum audit_state    state, current_state;
-	unsigned int	    serial;     /* serial number for record */
+	struct audit_stamp  stamp;	/* event identifier */
 	int		    major;      /* syscall number */
 	int		    uring_op;   /* uring operation */
-	struct timespec64   ctime;      /* time of syscall entry */
 	unsigned long	    argv[4];    /* syscall arguments */
 	long		    return_code;/* syscall return code */
 	u64		    prio;
@@ -263,7 +268,7 @@ extern void audit_put_tty(struct tty_struct *tty);
 extern unsigned int audit_serial(void);
 #ifdef CONFIG_AUDITSYSCALL
 extern int auditsc_get_stamp(struct audit_context *ctx,
-			      struct timespec64 *t, unsigned int *serial);
+			     struct audit_stamp *stamp);
 
 extern void audit_put_watch(struct audit_watch *watch);
 extern void audit_get_watch(struct audit_watch *watch);
@@ -304,7 +309,7 @@ extern void audit_filter_inodes(struct task_struct *tsk,
 				struct audit_context *ctx);
 extern struct list_head *audit_killed_trees(void);
 #else /* CONFIG_AUDITSYSCALL */
-#define auditsc_get_stamp(c, t, s) 0
+#define auditsc_get_stamp(c, s) 0
 #define audit_put_watch(w) do { } while (0)
 #define audit_get_watch(w) do { } while (0)
 #define audit_to_watch(k, p, l, o) (-EINVAL)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 78fd876a5473..528b6d2f5cb0 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -994,10 +994,10 @@ static void audit_reset_context(struct audit_context *ctx)
 	 */
 
 	ctx->current_state = ctx->state;
-	ctx->serial = 0;
+	ctx->stamp.serial = 0;
+	ctx->stamp.ctime = (struct timespec64){ .tv_sec = 0, .tv_nsec = 0 };
 	ctx->major = 0;
 	ctx->uring_op = 0;
-	ctx->ctime = (struct timespec64){ .tv_sec = 0, .tv_nsec = 0 };
 	memset(ctx->argv, 0, sizeof(ctx->argv));
 	ctx->return_code = 0;
 	ctx->prio = (ctx->state == AUDIT_STATE_RECORD ? ~0ULL : 0);
@@ -1917,7 +1917,7 @@ void __audit_uring_entry(u8 op)
 
 	ctx->context = AUDIT_CTX_URING;
 	ctx->current_state = ctx->state;
-	ktime_get_coarse_real_ts64(&ctx->ctime);
+	ktime_get_coarse_real_ts64(&ctx->stamp.ctime);
 }
 
 /**
@@ -2039,7 +2039,7 @@ void __audit_syscall_entry(int major, unsigned long a1, unsigned long a2,
 	context->argv[3]    = a4;
 	context->context = AUDIT_CTX_SYSCALL;
 	context->current_state  = state;
-	ktime_get_coarse_real_ts64(&context->ctime);
+	ktime_get_coarse_real_ts64(&context->stamp.ctime);
 }
 
 /**
@@ -2508,21 +2508,17 @@ EXPORT_SYMBOL_GPL(__audit_inode_child);
 /**
  * auditsc_get_stamp - get local copies of audit_context values
  * @ctx: audit_context for the task
- * @t: timespec64 to store time recorded in the audit_context
- * @serial: serial value that is recorded in the audit_context
+ * @stamp: timestamp to record
  *
  * Also sets the context as auditable.
  */
-int auditsc_get_stamp(struct audit_context *ctx,
-		       struct timespec64 *t, unsigned int *serial)
+int auditsc_get_stamp(struct audit_context *ctx, struct audit_stamp *stamp)
 {
 	if (ctx->context == AUDIT_CTX_UNUSED)
 		return 0;
-	if (!ctx->serial)
-		ctx->serial = audit_serial();
-	t->tv_sec  = ctx->ctime.tv_sec;
-	t->tv_nsec = ctx->ctime.tv_nsec;
-	*serial    = ctx->serial;
+	if (!ctx->stamp.serial)
+		ctx->stamp.serial = audit_serial();
+	*stamp = ctx->stamp;
 	if (!ctx->prio) {
 		ctx->prio = 1;
 		ctx->current_state = AUDIT_STATE_RECORD;
-- 
2.50.1

[PATCH v5 2/5] LSM: security_lsmblob_to_secctx module selection

[Casey Schaufler]

Add a parameter lsmid to security_lsmblob_to_secctx() to identify which
of the security modules that may be active should provide the security
context. If the value of lsmid is LSM_ID_UNDEF the first LSM providing
a hook is used. security_secid_to_secctx() is unchanged, and will
always report the first LSM providing a hook.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 include/linux/security.h     |  6 ++++--
 kernel/audit.c               |  4 ++--
 kernel/auditsc.c             |  8 +++++---
 net/netlabel/netlabel_user.c |  3 ++-
 security/security.c          | 18 ++++++++++++++++--
 5 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index c032ec4e95ff..5fbe38521938 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -564,7 +564,8 @@ int security_getprocattr(struct task_struct *p, int lsmid, const char *name,
 int security_setprocattr(int lsmid, const char *name, void *value, size_t size);
 int security_ismaclabel(const char *name);
 int security_secid_to_secctx(u32 secid, struct lsm_context *cp);
-int security_lsmprop_to_secctx(struct lsm_prop *prop, struct lsm_context *cp);
+int security_lsmprop_to_secctx(struct lsm_prop *prop, struct lsm_context *cp,
+			       int lsmid);
 int security_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
 void security_release_secctx(struct lsm_context *cp);
 void security_inode_invalidate_secctx(struct inode *inode);
@@ -1536,7 +1537,8 @@ static inline int security_secid_to_secctx(u32 secid, struct lsm_context *cp)
 }
 
 static inline int security_lsmprop_to_secctx(struct lsm_prop *prop,
-					     struct lsm_context *cp)
+					     struct lsm_context *cp,
+					     int lsmid)
 {
 	return -EOPNOTSUPP;
 }
diff --git a/kernel/audit.c b/kernel/audit.c
index 547967cb4266..226c8ae00d04 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1473,7 +1473,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 	case AUDIT_SIGNAL_INFO:
 		if (lsmprop_is_set(&audit_sig_lsm)) {
 			err = security_lsmprop_to_secctx(&audit_sig_lsm,
-							 &lsmctx);
+							 &lsmctx, LSM_ID_UNDEF);
 			if (err < 0)
 				return err;
 		}
@@ -2188,7 +2188,7 @@ int audit_log_task_context(struct audit_buffer *ab)
 	if (!lsmprop_is_set(&prop))
 		return 0;
 
-	error = security_lsmprop_to_secctx(&prop, &ctx);
+	error = security_lsmprop_to_secctx(&prop, &ctx, LSM_ID_UNDEF);
 	if (error < 0) {
 		if (error != -EINVAL)
 			goto error_path;
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 528b6d2f5cb0..322d4e27f28e 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1109,7 +1109,7 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
 			 from_kuid(&init_user_ns, auid),
 			 from_kuid(&init_user_ns, uid), sessionid);
 	if (lsmprop_is_set(prop)) {
-		if (security_lsmprop_to_secctx(prop, &ctx) < 0) {
+		if (security_lsmprop_to_secctx(prop, &ctx, LSM_ID_UNDEF) < 0) {
 			audit_log_format(ab, " obj=(none)");
 			rc = 1;
 		} else {
@@ -1395,7 +1395,8 @@ static void show_special(struct audit_context *context, int *call_panic)
 			struct lsm_context lsmctx;
 
 			if (security_lsmprop_to_secctx(&context->ipc.oprop,
-						       &lsmctx) < 0) {
+						       &lsmctx,
+						       LSM_ID_UNDEF) < 0) {
 				*call_panic = 1;
 			} else {
 				audit_log_format(ab, " obj=%s", lsmctx.context);
@@ -1560,7 +1561,8 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
 	if (lsmprop_is_set(&n->oprop)) {
 		struct lsm_context ctx;
 
-		if (security_lsmprop_to_secctx(&n->oprop, &ctx) < 0) {
+		if (security_lsmprop_to_secctx(&n->oprop, &ctx,
+					       LSM_ID_UNDEF) < 0) {
 			if (call_panic)
 				*call_panic = 2;
 		} else {
diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
index 0d04d23aafe7..6d6545297ee3 100644
--- a/net/netlabel/netlabel_user.c
+++ b/net/netlabel/netlabel_user.c
@@ -98,7 +98,8 @@ struct audit_buffer *netlbl_audit_start_common(int type,
 			 audit_info->sessionid);
 
 	if (lsmprop_is_set(&audit_info->prop) &&
-	    security_lsmprop_to_secctx(&audit_info->prop, &ctx) > 0) {
+	    security_lsmprop_to_secctx(&audit_info->prop, &ctx,
+				       LSM_ID_UNDEF) > 0) {
 		audit_log_format(audit_buf, " subj=%s", ctx.context);
 		security_release_secctx(&ctx);
 	}
diff --git a/security/security.c b/security/security.c
index 8a4e0f70e49d..2cc832dc8a45 100644
--- a/security/security.c
+++ b/security/security.c
@@ -3774,17 +3774,31 @@ EXPORT_SYMBOL(security_secid_to_secctx);
  * security_lsmprop_to_secctx() - Convert a lsm_prop to a secctx
  * @prop: lsm specific information
  * @cp: the LSM context
+ * @lsmid: which security module to report
  *
  * Convert a @prop entry to security context.  If @cp is NULL the
  * length of the result will be returned. This does mean that the
  * length could change between calls to check the length and the
  * next call which actually allocates and returns the @cp.
  *
+ * @lsmid identifies which LSM should supply the context.
+ * A value of LSM_ID_UNDEF indicates that the first LSM suppling
+ * the hook should be used. This is used in cases where the
+ * ID of the supplying LSM is unambiguous.
+ *
  * Return: Return length of data on success, error on failure.
  */
-int security_lsmprop_to_secctx(struct lsm_prop *prop, struct lsm_context *cp)
+int security_lsmprop_to_secctx(struct lsm_prop *prop, struct lsm_context *cp,
+			       int lsmid)
 {
-	return call_int_hook(lsmprop_to_secctx, prop, cp);
+	struct lsm_static_call *scall;
+
+	lsm_for_each_hook(scall, lsmprop_to_secctx) {
+		if (lsmid != LSM_ID_UNDEF && lsmid != scall->hl->lsmid->id)
+			continue;
+		return scall->hl->hook.lsmprop_to_secctx(prop, cp);
+	}
+	return LSM_RET_DEFAULT(lsmprop_to_secctx);
 }
 EXPORT_SYMBOL(security_lsmprop_to_secctx);
 
-- 
2.50.1

[PATCH v5 3/5] Audit: Add record for multiple task security contexts

[Casey Schaufler]

Replace the single skb pointer in an audit_buffer with a list of
skb pointers. Add the audit_stamp information to the audit_buffer as
there's no guarantee that there will be an audit_context containing
the stamp associated with the event. At audit_log_end() time create
auxiliary records as have been added to the list. Functions are
created to manage the skb list in the audit_buffer.

Create a new audit record AUDIT_MAC_TASK_CONTEXTS.
An example of the MAC_TASK_CONTEXTS record is:

    type=MAC_TASK_CONTEXTS
    msg=audit(1600880931.832:113)
    subj_apparmor=unconfined
    subj_smack=_

When an audit event includes a AUDIT_MAC_TASK_CONTEXTS record the
"subj=" field in other records in the event will be "subj=?".
An AUDIT_MAC_TASK_CONTEXTS record is supplied when the system has
multiple security modules that may make access decisions based on a
subject security context.

Refactor audit_log_task_context(), creating a new audit_log_subj_ctx().
This is used in netlabel auditing to provide multiple subject security
contexts as necessary.

Suggested-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 include/linux/audit.h        |  16 +++
 include/uapi/linux/audit.h   |   1 +
 kernel/audit.c               | 207 +++++++++++++++++++++++++++++------
 net/netlabel/netlabel_user.c |   9 +-
 security/apparmor/lsm.c      |   3 +
 security/lsm.h               |   4 -
 security/lsm_init.c          |   5 -
 security/security.c          |   3 -
 security/selinux/hooks.c     |   3 +
 security/smack/smack_lsm.c   |   3 +
 10 files changed, 202 insertions(+), 52 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 0050ef288ab3..fb54c1119947 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -37,6 +37,8 @@ struct audit_watch;
 struct audit_tree;
 struct sk_buff;
 struct kern_ipc_perm;
+struct lsm_id;
+struct lsm_prop;
 
 struct audit_krule {
 	u32			pflags;
@@ -147,6 +149,9 @@ extern unsigned compat_signal_class[];
 #define AUDIT_TTY_ENABLE	BIT(0)
 #define AUDIT_TTY_LOG_PASSWD	BIT(1)
 
+/* bit values for audit_cfg_lsm */
+#define AUDIT_CFG_LSM_SECCTX_SUBJECT	BIT(0)
+
 struct filename;
 
 #define AUDIT_OFF	0
@@ -185,6 +190,7 @@ extern void		    audit_log_path_denied(int type,
 						  const char *operation);
 extern void		    audit_log_lost(const char *message);
 
+extern int audit_log_subj_ctx(struct audit_buffer *ab, struct lsm_prop *prop);
 extern int audit_log_task_context(struct audit_buffer *ab);
 extern void audit_log_task_info(struct audit_buffer *ab);
 
@@ -210,6 +216,8 @@ extern u32 audit_enabled;
 
 extern int audit_signal_info(int sig, struct task_struct *t);
 
+extern void audit_cfg_lsm(const struct lsm_id *lsmid, int flags);
+
 #else /* CONFIG_AUDIT */
 static inline __printf(4, 5)
 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
@@ -245,6 +253,11 @@ static inline void audit_log_key(struct audit_buffer *ab, char *key)
 { }
 static inline void audit_log_path_denied(int type, const char *operation)
 { }
+static inline int audit_log_subj_ctx(struct audit_buffer *ab,
+				     struct lsm_prop *prop)
+{
+	return 0;
+}
 static inline int audit_log_task_context(struct audit_buffer *ab)
 {
 	return 0;
@@ -269,6 +282,9 @@ static inline int audit_signal_info(int sig, struct task_struct *t)
 	return 0;
 }
 
+static inline void audit_cfg_lsm(const struct lsm_id *lsmid, int flags)
+{ }
+
 #endif /* CONFIG_AUDIT */
 
 #ifdef CONFIG_AUDIT_COMPAT_GENERIC
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 9a4ecc9f6dc5..8cad2f307719 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -148,6 +148,7 @@
 #define AUDIT_IPE_POLICY_LOAD	1422	/* IPE policy load */
 #define AUDIT_LANDLOCK_ACCESS	1423	/* Landlock denial */
 #define AUDIT_LANDLOCK_DOMAIN	1424	/* Landlock domain status */
+#define AUDIT_MAC_TASK_CONTEXTS	1425	/* Multiple LSM task contexts */
 
 #define AUDIT_FIRST_KERN_ANOM_MSG   1700
 #define AUDIT_LAST_KERN_ANOM_MSG    1799
diff --git a/kernel/audit.c b/kernel/audit.c
index 226c8ae00d04..c7dea6bfacdd 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -54,6 +54,7 @@
 #include <net/netlink.h>
 #include <linux/skbuff.h>
 #include <linux/security.h>
+#include <linux/lsm_hooks.h>
 #include <linux/freezer.h>
 #include <linux/pid_namespace.h>
 #include <net/netns/generic.h>
@@ -81,6 +82,11 @@ static u32	audit_failure = AUDIT_FAIL_PRINTK;
 /* private audit network namespace index */
 static unsigned int audit_net_id;
 
+/* Number of modules that provide a security context.
+   List of lsms that provide a security context */
+static u32 audit_subj_secctx_cnt;
+static const struct lsm_id *audit_subj_lsms[MAX_LSM_COUNT];
+
 /**
  * struct audit_net - audit private network namespace data
  * @sk: communication socket
@@ -195,8 +201,10 @@ static struct audit_ctl_mutex {
  * to place it on a transmit queue.  Multiple audit_buffers can be in
  * use simultaneously. */
 struct audit_buffer {
-	struct sk_buff       *skb;	/* formatted skb ready to send */
+	struct sk_buff       *skb;	/* the skb for audit_log functions */
+	struct sk_buff_head  skb_list;	/* formatted skbs, ready to send */
 	struct audit_context *ctx;	/* NULL or associated context */
+	struct audit_stamp   stamp;	/* audit stamp for these records */
 	gfp_t		     gfp_mask;
 };
 
@@ -278,6 +286,27 @@ static pid_t auditd_pid_vnr(void)
 	return pid;
 }
 
+/**
+ * audit_cfg_lsm - Identify a security module as providing a secctx.
+ * @lsmid: LSM identity
+ * @flags: which contexts are provided
+ *
+ * Description:
+ * Increments the count of the security modules providing a secctx.
+ * If the LSM id is already in the list leave it alone.
+ */
+void audit_cfg_lsm(const struct lsm_id *lsmid, int flags)
+{
+	int i;
+
+	if (flags & AUDIT_CFG_LSM_SECCTX_SUBJECT) {
+		for (i = 0 ; i < audit_subj_secctx_cnt; i++)
+			if (audit_subj_lsms[i] == lsmid)
+				return;
+		audit_subj_lsms[audit_subj_secctx_cnt++] = lsmid;
+	}
+}
+
 /**
  * audit_get_sk - Return the audit socket for the given network namespace
  * @net: the destination network namespace
@@ -1776,10 +1805,13 @@ __setup("audit_backlog_limit=", audit_backlog_limit_set);
 
 static void audit_buffer_free(struct audit_buffer *ab)
 {
+	struct sk_buff *skb;
+
 	if (!ab)
 		return;
 
-	kfree_skb(ab->skb);
+	while ((skb = skb_dequeue(&ab->skb_list)))
+		kfree_skb(skb);
 	kmem_cache_free(audit_buffer_cache, ab);
 }
 
@@ -1795,6 +1827,10 @@ static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx,
 	ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
 	if (!ab->skb)
 		goto err;
+
+	skb_queue_head_init(&ab->skb_list);
+	skb_queue_tail(&ab->skb_list, ab->skb);
+
 	if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
 		goto err;
 
@@ -1860,7 +1896,6 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 				     int type)
 {
 	struct audit_buffer *ab;
-	struct audit_stamp stamp;
 
 	if (audit_initialized != AUDIT_INITIALIZED)
 		return NULL;
@@ -1915,14 +1950,14 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 		return NULL;
 	}
 
-	audit_get_stamp(ab->ctx, &stamp);
+	audit_get_stamp(ab->ctx, &ab->stamp);
 	/* cancel dummy context to enable supporting records */
 	if (ctx)
 		ctx->dummy = 0;
 	audit_log_format(ab, "audit(%llu.%03lu:%u): ",
-			 (unsigned long long)stamp.ctime.tv_sec,
-			 stamp.ctime.tv_nsec/1000000,
-			 stamp.serial);
+			 (unsigned long long)ab->stamp.ctime.tv_sec,
+			 ab->stamp.ctime.tv_nsec/1000000,
+			 ab->stamp.serial);
 
 	return ab;
 }
@@ -2178,31 +2213,128 @@ void audit_log_key(struct audit_buffer *ab, char *key)
 		audit_log_format(ab, "(null)");
 }
 
-int audit_log_task_context(struct audit_buffer *ab)
+/**
+ * audit_buffer_aux_new - Add an aux record buffer to the skb list
+ * @ab: audit_buffer
+ * @type: message type
+ *
+ * Aux records are allocated and added to the skb list of
+ * the "main" record. The ab->skb is reset to point to the
+ * aux record on its creation. When the aux record in complete
+ * ab->skb has to be reset to point to the "main" record.
+ * This allows the audit_log_ functions to be ignorant of
+ * which kind of record it is logging to. It also avoids adding
+ * special data for aux records.
+ *
+ * On success ab->skb will point to the new aux record.
+ * Returns 0 on success, -ENOMEM should allocation fail.
+ */
+static int audit_buffer_aux_new(struct audit_buffer *ab, int type)
+{
+	WARN_ON(ab->skb != skb_peek(&ab->skb_list));
+
+	ab->skb = nlmsg_new(AUDIT_BUFSIZ, ab->gfp_mask);
+	if (!ab->skb)
+		goto err;
+	if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
+		goto err;
+	skb_queue_tail(&ab->skb_list, ab->skb);
+
+	audit_log_format(ab, "audit(%llu.%03lu:%u): ",
+			 (unsigned long long)ab->stamp.ctime.tv_sec,
+			 ab->stamp.ctime.tv_nsec/1000000,
+			 ab->stamp.serial);
+
+	return 0;
+
+err:
+	kfree_skb(ab->skb);
+	ab->skb = skb_peek(&ab->skb_list);
+	return -ENOMEM;
+}
+
+/**
+ * audit_buffer_aux_end - Switch back to the "main" record from an aux record
+ * @ab: audit_buffer
+ *
+ * Restores the "main" audit record to ab->skb.
+ */
+static void audit_buffer_aux_end(struct audit_buffer *ab)
+{
+	ab->skb = skb_peek(&ab->skb_list);
+}
+
+/**
+ * audit_log_subj_ctx - Add LSM subject information
+ * @ab: audit_buffer
+ * @prop: LSM subject properties.
+ *
+ * Add a subj= field and, if necessary, a AUDIT_MAC_TASK_CONTEXTS record.
+ */
+int audit_log_subj_ctx(struct audit_buffer *ab, struct lsm_prop *prop)
 {
-	struct lsm_prop prop;
 	struct lsm_context ctx;
+	char *space = "";
 	int error;
+	int i;
 
-	security_current_getlsmprop_subj(&prop);
-	if (!lsmprop_is_set(&prop))
+	security_current_getlsmprop_subj(prop);
+	if (!lsmprop_is_set(prop))
 		return 0;
 
-	error = security_lsmprop_to_secctx(&prop, &ctx, LSM_ID_UNDEF);
-	if (error < 0) {
-		if (error != -EINVAL)
-			goto error_path;
+	if (audit_subj_secctx_cnt < 2) {
+		error = security_lsmprop_to_secctx(prop, &ctx, LSM_ID_UNDEF);
+		if (error < 0) {
+			if (error != -EINVAL)
+				goto error_path;
+			return 0;
+		}
+		audit_log_format(ab, " subj=%s", ctx.context);
+		security_release_secctx(&ctx);
 		return 0;
 	}
-
-	audit_log_format(ab, " subj=%s", ctx.context);
-	security_release_secctx(&ctx);
+	/* Multiple LSMs provide contexts. Include an aux record. */
+	audit_log_format(ab, " subj=?");
+	error = audit_buffer_aux_new(ab, AUDIT_MAC_TASK_CONTEXTS);
+	if (error)
+		goto error_path;
+
+	for (i = 0; i < audit_subj_secctx_cnt; i++) {
+		error = security_lsmprop_to_secctx(prop, &ctx,
+						   audit_subj_lsms[i]->id);
+		if (error < 0) {
+			/*
+			 * Don't print anything. An LSM like BPF could
+			 * claim to support contexts, but only do so under
+			 * certain conditions.
+			 */
+			if (error == -EOPNOTSUPP)
+				continue;
+			if (error != -EINVAL)
+				audit_panic("error in audit_log_task_context");
+		} else {
+			audit_log_format(ab, "%ssubj_%s=%s", space,
+					 audit_subj_lsms[i]->name, ctx.context);
+			space = " ";
+			security_release_secctx(&ctx);
+		}
+	}
+	audit_buffer_aux_end(ab);
 	return 0;
 
 error_path:
-	audit_panic("error in audit_log_task_context");
+	audit_panic("error in audit_log_subj_ctx");
 	return error;
 }
+EXPORT_SYMBOL(audit_log_subj_ctx);
+
+int audit_log_task_context(struct audit_buffer *ab)
+{
+	struct lsm_prop prop;
+
+	security_current_getlsmprop_subj(&prop);
+	return audit_log_subj_ctx(ab, &prop);
+}
 EXPORT_SYMBOL(audit_log_task_context);
 
 void audit_log_d_path_exe(struct audit_buffer *ab,
@@ -2411,6 +2543,26 @@ int audit_signal_info(int sig, struct task_struct *t)
 	return audit_signal_info_syscall(t);
 }
 
+/**
+ * __audit_log_end - enqueue one audit record
+ * @skb: the buffer to send
+ */
+static void __audit_log_end(struct sk_buff *skb)
+{
+	struct nlmsghdr *nlh;
+
+	if (audit_rate_check()) {
+		/* setup the netlink header, see the comments in
+		 * kauditd_send_multicast_skb() for length quirks */
+		nlh = nlmsg_hdr(skb);
+		nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
+
+		/* queue the netlink packet */
+		skb_queue_tail(&audit_queue, skb);
+	} else
+		audit_log_lost("rate limit exceeded");
+}
+
 /**
  * audit_log_end - end one audit record
  * @ab: the audit_buffer
@@ -2423,25 +2575,16 @@ int audit_signal_info(int sig, struct task_struct *t)
 void audit_log_end(struct audit_buffer *ab)
 {
 	struct sk_buff *skb;
-	struct nlmsghdr *nlh;
 
 	if (!ab)
 		return;
 
-	if (audit_rate_check()) {
-		skb = ab->skb;
-		ab->skb = NULL;
+	while ((skb = skb_dequeue(&ab->skb_list)))
+		__audit_log_end(skb);
 
-		/* setup the netlink header, see the comments in
-		 * kauditd_send_multicast_skb() for length quirks */
-		nlh = nlmsg_hdr(skb);
-		nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
-
-		/* queue the netlink packet and poke the kauditd thread */
-		skb_queue_tail(&audit_queue, skb);
+	/* poke the kauditd thread */
+	if (audit_rate_check())
 		wake_up_interruptible(&kauditd_wait);
-	} else
-		audit_log_lost("rate limit exceeded");
 
 	audit_buffer_free(ab);
 }
diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
index 6d6545297ee3..0da652844dd6 100644
--- a/net/netlabel/netlabel_user.c
+++ b/net/netlabel/netlabel_user.c
@@ -84,7 +84,6 @@ struct audit_buffer *netlbl_audit_start_common(int type,
 					       struct netlbl_audit *audit_info)
 {
 	struct audit_buffer *audit_buf;
-	struct lsm_context ctx;
 
 	if (audit_enabled == AUDIT_OFF)
 		return NULL;
@@ -96,13 +95,7 @@ struct audit_buffer *netlbl_audit_start_common(int type,
 	audit_log_format(audit_buf, "netlabel: auid=%u ses=%u",
 			 from_kuid(&init_user_ns, audit_info->loginuid),
 			 audit_info->sessionid);
-
-	if (lsmprop_is_set(&audit_info->prop) &&
-	    security_lsmprop_to_secctx(&audit_info->prop, &ctx,
-				       LSM_ID_UNDEF) > 0) {
-		audit_log_format(audit_buf, " subj=%s", ctx.context);
-		security_release_secctx(&ctx);
-	}
+	audit_log_subj_ctx(audit_buf, &audit_info->prop);
 
 	return audit_buf;
 }
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index db8592bed189..a74825eebba0 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -2251,6 +2251,9 @@ static int __init apparmor_init(void)
 	security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks),
 				&apparmor_lsmid);
 
+	/* Inform the audit system that secctx is used */
+	audit_cfg_lsm(&apparmor_lsmid, AUDIT_CFG_LSM_SECCTX_SUBJECT);
+
 	/* Report that AppArmor successfully initialized */
 	apparmor_initialized = 1;
 	if (aa_g_profile_mode == APPARMOR_COMPLAIN)
diff --git a/security/lsm.h b/security/lsm.h
index d1d54540da98..c432dc0c5e30 100644
--- a/security/lsm.h
+++ b/security/lsm.h
@@ -24,10 +24,6 @@ extern bool lsm_debug;
 extern unsigned int lsm_count;
 extern const struct lsm_id *lsm_idlist[];
 
-/* LSM property configuration */
-extern unsigned int lsm_count_prop_subj;
-extern unsigned int lsm_count_prop_obj;
-
 /* LSM blob configuration */
 extern struct lsm_blob_sizes blob_sizes;
 
diff --git a/security/lsm_init.c b/security/lsm_init.c
index c2ef4db055db..54166688efff 100644
--- a/security/lsm_init.c
+++ b/security/lsm_init.c
@@ -190,11 +190,6 @@ static void __init lsm_order_append(struct lsm_info *lsm, const char *src)
 	lsm_order[lsm_count] = lsm;
 	lsm_idlist[lsm_count++] = lsm->id;
 
-	if (lsm->id->flags & LSM_ID_FLG_PROP_SUBJ)
-		lsm_count_prop_subj++;
-	if (lsm->id->flags & LSM_ID_FLG_PROP_OBJ)
-		lsm_count_prop_obj++;
-
 	lsm_pr_dbg("enabling LSM %s:%s\n", src, lsm->id->name);
 }
 
diff --git a/security/security.c b/security/security.c
index 2cc832dc8a45..678b261e91de 100644
--- a/security/security.c
+++ b/security/security.c
@@ -78,9 +78,6 @@ bool lsm_debug __ro_after_init;
 unsigned int lsm_count __ro_after_init;
 const struct lsm_id *lsm_idlist[MAX_LSM_COUNT];
 
-unsigned int lsm_count_prop_subj __ro_after_init;
-unsigned int lsm_count_prop_obj __ro_after_init;
-
 struct lsm_blob_sizes blob_sizes;
 
 struct kmem_cache *lsm_file_cache;
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index b00c2627286a..81b66b4d9695 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -7594,6 +7594,9 @@ static __init int selinux_init(void)
 	/* Set the security state for the initial task. */
 	cred_init_security();
 
+	/* Inform the audit system that secctx is used */
+	audit_cfg_lsm(&selinux_lsmid, AUDIT_CFG_LSM_SECCTX_SUBJECT);
+
 	default_noexec = !(VM_DATA_DEFAULT_FLAGS & VM_EXEC);
 	if (!default_noexec)
 		pr_notice("SELinux:  virtual memory is executable by default\n");
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 46ef5ece991c..9a76821b7191 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -5268,6 +5268,9 @@ static __init int smack_init(void)
 	/* initialize the smack_known_list */
 	init_smack_known_list();
 
+	/* Inform the audit system that secctx is used */
+	audit_cfg_lsm(&smack_lsmid, AUDIT_CFG_LSM_SECCTX_SUBJECT);
+
 	return 0;
 }
 
-- 
2.50.1

[PATCH v5 4/5] Audit: Fix indentation in audit_log_exit

[Casey Schaufler]

Fix two indentation errors in audit_log_exit().

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 kernel/auditsc.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 322d4e27f28e..84173d234d4a 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1780,15 +1780,16 @@ static void audit_log_exit(void)
 						  axs->target_sessionid[i],
 						  &axs->target_ref[i],
 						  axs->target_comm[i]))
-				call_panic = 1;
+			call_panic = 1;
 	}
 
 	if (context->target_pid &&
 	    audit_log_pid_context(context, context->target_pid,
 				  context->target_auid, context->target_uid,
 				  context->target_sessionid,
-				  &context->target_ref, context->target_comm))
-			call_panic = 1;
+				  &context->target_ref,
+				  context->target_comm))
+		call_panic = 1;
 
 	if (context->pwd.dentry && context->pwd.mnt) {
 		ab = audit_log_start(context, GFP_KERNEL, AUDIT_CWD);
-- 
2.50.1

[PATCH v5 5/5] Audit: Add record for multiple object contexts

[Casey Schaufler]

Create a new audit record AUDIT_MAC_OBJ_CONTEXTS.
An example of the MAC_OBJ_CONTEXTS record is:

    type=MAC_OBJ_CONTEXTS
    msg=audit(1601152467.009:1050):
    obj_selinux=unconfined_u:object_r:user_home_t:s0

When an audit event includes a AUDIT_MAC_OBJ_CONTEXTS record
the "obj=" field in other records in the event will be "obj=?".
An AUDIT_MAC_OBJ_CONTEXTS record is supplied when the system has
multiple security modules that may make access decisions based
on an object security context.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 include/linux/audit.h      |  7 +++++
 include/uapi/linux/audit.h |  1 +
 kernel/audit.c             | 58 +++++++++++++++++++++++++++++++++++++-
 kernel/auditsc.c           | 38 +++++--------------------
 security/selinux/hooks.c   |  4 ++-
 security/smack/smack_lsm.c |  4 ++-
 6 files changed, 78 insertions(+), 34 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index fb54c1119947..56944fbc1e58 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -151,6 +151,7 @@ extern unsigned compat_signal_class[];
 
 /* bit values for audit_cfg_lsm */
 #define AUDIT_CFG_LSM_SECCTX_SUBJECT	BIT(0)
+#define AUDIT_CFG_LSM_SECCTX_OBJECT	BIT(1)
 
 struct filename;
 
@@ -191,6 +192,7 @@ extern void		    audit_log_path_denied(int type,
 extern void		    audit_log_lost(const char *message);
 
 extern int audit_log_subj_ctx(struct audit_buffer *ab, struct lsm_prop *prop);
+extern int audit_log_obj_ctx(struct audit_buffer *ab, struct lsm_prop *prop);
 extern int audit_log_task_context(struct audit_buffer *ab);
 extern void audit_log_task_info(struct audit_buffer *ab);
 
@@ -258,6 +260,11 @@ static inline int audit_log_subj_ctx(struct audit_buffer *ab,
 {
 	return 0;
 }
+static inline int audit_log_obj_ctx(struct audit_buffer *ab,
+				    struct lsm_prop *prop)
+{
+	return 0;
+}
 static inline int audit_log_task_context(struct audit_buffer *ab)
 {
 	return 0;
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 8cad2f307719..14a1c1fe013a 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -149,6 +149,7 @@
 #define AUDIT_LANDLOCK_ACCESS	1423	/* Landlock denial */
 #define AUDIT_LANDLOCK_DOMAIN	1424	/* Landlock domain status */
 #define AUDIT_MAC_TASK_CONTEXTS	1425	/* Multiple LSM task contexts */
+#define AUDIT_MAC_OBJ_CONTEXTS	1426	/* Multiple LSM objext contexts */
 
 #define AUDIT_FIRST_KERN_ANOM_MSG   1700
 #define AUDIT_LAST_KERN_ANOM_MSG    1799
diff --git a/kernel/audit.c b/kernel/audit.c
index c7dea6bfacdd..63c69db43172 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -85,7 +85,9 @@ static unsigned int audit_net_id;
 /* Number of modules that provide a security context.
    List of lsms that provide a security context */
 static u32 audit_subj_secctx_cnt;
+static u32 audit_obj_secctx_cnt;
 static const struct lsm_id *audit_subj_lsms[MAX_LSM_COUNT];
+static const struct lsm_id *audit_obj_lsms[MAX_LSM_COUNT];
 
 /**
  * struct audit_net - audit private network namespace data
@@ -305,6 +307,12 @@ void audit_cfg_lsm(const struct lsm_id *lsmid, int flags)
 				return;
 		audit_subj_lsms[audit_subj_secctx_cnt++] = lsmid;
 	}
+	if (flags & AUDIT_CFG_LSM_SECCTX_OBJECT) {
+		for (i = 0 ; i < audit_obj_secctx_cnt; i++)
+			if (audit_obj_lsms[i] == lsmid)
+				return;
+		audit_obj_lsms[audit_obj_secctx_cnt++] = lsmid;
+	}
 }
 
 /**
@@ -1142,7 +1150,6 @@ static int is_audit_feature_set(int i)
 	return af.features & AUDIT_FEATURE_TO_MASK(i);
 }
 
-
 static int audit_get_feature(struct sk_buff *skb)
 {
 	u32 seq;
@@ -2337,6 +2344,55 @@ int audit_log_task_context(struct audit_buffer *ab)
 }
 EXPORT_SYMBOL(audit_log_task_context);
 
+int audit_log_obj_ctx(struct audit_buffer *ab, struct lsm_prop *prop)
+{
+	int i;
+	int rc;
+	int error = 0;
+	char *space = "";
+	struct lsm_context ctx;
+
+	if (audit_obj_secctx_cnt < 2) {
+		error = security_lsmprop_to_secctx(prop, &ctx, LSM_ID_UNDEF);
+		if (error < 0) {
+			if (error != -EINVAL)
+				goto error_path;
+			return error;
+		}
+		audit_log_format(ab, " obj=%s", ctx.context);
+		security_release_secctx(&ctx);
+		return 0;
+	}
+	audit_log_format(ab, " obj=?");
+	error = audit_buffer_aux_new(ab, AUDIT_MAC_OBJ_CONTEXTS);
+	if (error)
+		goto error_path;
+
+	for (i = 0; i < audit_obj_secctx_cnt; i++) {
+		rc = security_lsmprop_to_secctx(prop, &ctx,
+						audit_obj_lsms[i]->id);
+		if (rc < 0) {
+			audit_log_format(ab, "%sobj_%s=?", space,
+					 audit_obj_lsms[i]->name);
+			if (rc != -EINVAL)
+				audit_panic("error in audit_log_obj_ctx");
+			error = rc;
+		} else {
+			audit_log_format(ab, "%sobj_%s=%s", space,
+					 audit_obj_lsms[i]->name, ctx.context);
+			security_release_secctx(&ctx);
+		}
+		space = " ";
+	}
+
+	audit_buffer_aux_end(ab);
+	return error;
+
+error_path:
+	audit_panic("error in audit_log_obj_ctx");
+	return error;
+}
+
 void audit_log_d_path_exe(struct audit_buffer *ab,
 			  struct mm_struct *mm)
 {
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 84173d234d4a..0c28fa33d099 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1098,7 +1098,6 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
 				 char *comm)
 {
 	struct audit_buffer *ab;
-	struct lsm_context ctx;
 	int rc = 0;
 
 	ab = audit_log_start(context, GFP_KERNEL, AUDIT_OBJ_PID);
@@ -1108,15 +1107,9 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
 	audit_log_format(ab, "opid=%d oauid=%d ouid=%d oses=%d", pid,
 			 from_kuid(&init_user_ns, auid),
 			 from_kuid(&init_user_ns, uid), sessionid);
-	if (lsmprop_is_set(prop)) {
-		if (security_lsmprop_to_secctx(prop, &ctx, LSM_ID_UNDEF) < 0) {
-			audit_log_format(ab, " obj=(none)");
-			rc = 1;
-		} else {
-			audit_log_format(ab, " obj=%s", ctx.context);
-			security_release_secctx(&ctx);
-		}
-	}
+	if (lsmprop_is_set(prop) && audit_log_obj_ctx(ab, prop))
+		rc = 1;
+
 	audit_log_format(ab, " ocomm=");
 	audit_log_untrustedstring(ab, comm);
 	audit_log_end(ab);
@@ -1392,16 +1385,8 @@ static void show_special(struct audit_context *context, int *call_panic)
 				 from_kgid(&init_user_ns, context->ipc.gid),
 				 context->ipc.mode);
 		if (lsmprop_is_set(&context->ipc.oprop)) {
-			struct lsm_context lsmctx;
-
-			if (security_lsmprop_to_secctx(&context->ipc.oprop,
-						       &lsmctx,
-						       LSM_ID_UNDEF) < 0) {
+			if (audit_log_obj_ctx(ab, &context->ipc.oprop))
 				*call_panic = 1;
-			} else {
-				audit_log_format(ab, " obj=%s", lsmctx.context);
-				security_release_secctx(&lsmctx);
-			}
 		}
 		if (context->ipc.has_perm) {
 			audit_log_end(ab);
@@ -1558,18 +1543,9 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
 				 from_kgid(&init_user_ns, n->gid),
 				 MAJOR(n->rdev),
 				 MINOR(n->rdev));
-	if (lsmprop_is_set(&n->oprop)) {
-		struct lsm_context ctx;
-
-		if (security_lsmprop_to_secctx(&n->oprop, &ctx,
-					       LSM_ID_UNDEF) < 0) {
-			if (call_panic)
-				*call_panic = 2;
-		} else {
-			audit_log_format(ab, " obj=%s", ctx.context);
-			security_release_secctx(&ctx);
-		}
-	}
+	if (lsmprop_is_set(&n->oprop) &&
+	    audit_log_obj_ctx(ab, &n->oprop))
+		*call_panic = 2;
 
 	/* log the audit_names record type */
 	switch (n->type) {
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 81b66b4d9695..11cd452c970b 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -7595,7 +7595,9 @@ static __init int selinux_init(void)
 	cred_init_security();
 
 	/* Inform the audit system that secctx is used */
-	audit_cfg_lsm(&selinux_lsmid, AUDIT_CFG_LSM_SECCTX_SUBJECT);
+	audit_cfg_lsm(&selinux_lsmid,
+		      AUDIT_CFG_LSM_SECCTX_SUBJECT |
+		      AUDIT_CFG_LSM_SECCTX_OBJECT);
 
 	default_noexec = !(VM_DATA_DEFAULT_FLAGS & VM_EXEC);
 	if (!default_noexec)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 9a76821b7191..5fe4b53fa40b 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -5269,7 +5269,9 @@ static __init int smack_init(void)
 	init_smack_known_list();
 
 	/* Inform the audit system that secctx is used */
-	audit_cfg_lsm(&smack_lsmid, AUDIT_CFG_LSM_SECCTX_SUBJECT);
+	audit_cfg_lsm(&smack_lsmid,
+		      AUDIT_CFG_LSM_SECCTX_SUBJECT |
+		      AUDIT_CFG_LSM_SECCTX_OBJECT);
 
 	return 0;
 }
-- 
2.50.1

Re: [PATCH v5 0/5] Audit: Records for multiple security contexts

[Casey Schaufler]

Opps. script error. Please disregard.


On 8/16/2025 9:41 AM, Casey Schaufler wrote:
> The Linux audit system includes LSM based security "context" information
> in its events. Historically, only one LSM that uses security contexts can
> be active on a system. One of the few obsticles to allowing multiple LSM
> support is the inability to report more than one security context in an
> audit event. This patchset provides a mechanism to provide supplimental
> records containing more than one security context for subjects and
> objects.
>
> The mechanism for reporting multiple security contexts inspired
> considerable discussion. It would have been possible to add multiple
> contexts to existing records using sophisticated formatting. This would
> have significant backward compatibility issues, and require additional
> parsing in user space code. Adding new records for an event that contain
> the contexts is more in keeping with the way audit events have been
> constructed in the past.
>
> Only audit events associated with system calls have required multiple
> records prior to this. Mechanism has been added allowing any event
> to be composed of multiple records. This should make it easier to
> add information to existing audit events without breaking backward
> compatability.
>
> v5:
> Comment on the LSM_ID_UNDEF behavior in security_secid_to_secctx().
> Change some names to better reflect their purpose.
> Move alignment changes into a separate patch.
> v4:
> Use LSM_ID_UNDEF when checking for valid LSM IDs in
> security_lsmprop_to_secctx().
> Fix the object record to include only those for LSMs that use them.
> Squash the two patches dealing with subject contexts.
> Base the patches on Paul Moore's LSM initialization patchset.
> https://lore.kernel.org/all/20250409185019.238841-31-paul@paul-moore.com/
> v3:
> Rework how security modules identify that they provide security
> contexts to the audit system. Maintain a list within the audit
> system of the security modules that provide security contexts.
> Revert the separate counts of subject and object contexts.
> v2:
> Maintain separate counts for LSMs using subject contexts and object
> contexts. AppArmor uses the former but not the latter.
> Correct error handling in object record creation.
>
> https://github.com/cschaufler/lsm-stacking#audit-6.16-rc4-v5
>
> Casey Schaufler (5):
>   Audit: Create audit_stamp structure
>   LSM: security_lsmblob_to_secctx module selection
>   Audit: Add record for multiple task security contexts
>   Audit: Fix indentation in audit_log_exit
>   Audit: Add record for multiple object contexts
>
>  include/linux/audit.h        |  23 +++
>  include/linux/security.h     |   6 +-
>  include/uapi/linux/audit.h   |   2 +
>  kernel/audit.c               | 274 ++++++++++++++++++++++++++++++-----
>  kernel/audit.h               |  13 +-
>  kernel/auditsc.c             |  65 +++------
>  net/netlabel/netlabel_user.c |   8 +-
>  security/apparmor/lsm.c      |   3 +
>  security/lsm.h               |   4 -
>  security/lsm_init.c          |   5 -
>  security/security.c          |  21 ++-
>  security/selinux/hooks.c     |   5 +
>  security/smack/smack_lsm.c   |   5 +
>  13 files changed, 325 insertions(+), 109 deletions(-)
>

[PATCH v5 0/5] Audit: Records for multiple security contexts

[Casey Schaufler]

The Linux audit system includes LSM based security "context" information
in its events. Historically, only one LSM that uses security contexts can
be active on a system. One of the few obsticles to allowing multiple LSM
support is the inability to report more than one security context in an
audit event. This patchset provides a mechanism to provide supplimental
records containing more than one security context for subjects and
objects.

The mechanism for reporting multiple security contexts inspired
considerable discussion. It would have been possible to add multiple
contexts to existing records using sophisticated formatting. This would
have significant backward compatibility issues, and require additional
parsing in user space code. Adding new records for an event that contain
the contexts is more in keeping with the way audit events have been
constructed in the past.

Only audit events associated with system calls have required multiple
records prior to this. Mechanism has been added allowing any event
to be composed of multiple records. This should make it easier to
add information to existing audit events without breaking backward
compatability.

v5:
Comment on the LSM_ID_UNDEF behavior in security_secid_to_secctx().
Change some names to better reflect their purpose.
Move alignment changes into a separate patch.
v4:
Use LSM_ID_UNDEF when checking for valid LSM IDs in
security_lsmprop_to_secctx().
Fix the object record to include only those for LSMs that use them.
Squash the two patches dealing with subject contexts.
Base the patches on Paul Moore's LSM initialization patchset.
https://lore.kernel.org/all/20250409185019.238841-31-paul@paul-moore.com/
v3:
Rework how security modules identify that they provide security
contexts to the audit system. Maintain a list within the audit
system of the security modules that provide security contexts.
Revert the separate counts of subject and object contexts.
v2:
Maintain separate counts for LSMs using subject contexts and object
contexts. AppArmor uses the former but not the latter.
Correct error handling in object record creation.

https://github.com/cschaufler/lsm-stacking#audit-6.16-rc4-v5

Casey Schaufler (5):
  Audit: Create audit_stamp structure
  LSM: security_lsmblob_to_secctx module selection
  Audit: Add record for multiple task security contexts
  Audit: Fix indentation in audit_log_exit
  Audit: Add record for multiple object contexts

 include/linux/audit.h        |  23 +++
 include/linux/security.h     |   6 +-
 include/uapi/linux/audit.h   |   2 +
 kernel/audit.c               | 274 ++++++++++++++++++++++++++++++-----
 kernel/audit.h               |  13 +-
 kernel/auditsc.c             |  65 +++------
 net/netlabel/netlabel_user.c |   8 +-
 security/apparmor/lsm.c      |   3 +
 security/lsm.h               |   4 -
 security/lsm_init.c          |   5 -
 security/security.c          |  21 ++-
 security/selinux/hooks.c     |   5 +
 security/smack/smack_lsm.c   |   5 +
 13 files changed, 325 insertions(+), 109 deletions(-)

-- 
2.50.1