[PATCH] audit: AUDIT_PERM support

add support for AUDIT_PERM predicate

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 69 insertions, 0 deletions

diff --git a/kernel/audit.h b/kernel/audit.h
index 6aa33b8..a337023 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -104,6 +104,7 @@ static inline int audit_hash_ino(u32 ino)
 	return (ino & (AUDIT_INODE_BUCKETS-1));
 }
 
+extern int audit_match_class(int class, unsigned syscall);
 extern int audit_comparator(const u32 left, const u32 op, const u32 right);
 extern int audit_compare_dname_path(const char *dname, const char *path,
 				    int *dirlen);
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index e4cafc1..a44879b 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -302,6 +302,15 @@ int __init audit_register_class(int class, unsigned *list)
 	return 0;
 }
 
+int audit_match_class(int class, unsigned syscall)
+{
+	if (unlikely(syscall >= AUDIT_BITMASK_SIZE * sizeof(__u32)))
+		return 0;
+	if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class]))
+		return 0;
+	return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall);
+}
+
 /* Common user-space to kernel rule translation. */
 static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
 {
@@ -414,6 +423,10 @@ static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
 		case AUDIT_ARG2:
 		case AUDIT_ARG3:
 			break;
+		case AUDIT_PERM:
+			if (f->val & ~15)
+				goto exit_free;
+			break;
 		case AUDIT_INODE:
 			err = audit_to_inode(&entry->rule, f);
 			if (err)
@@ -568,6 +581,10 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
 			entry->rule.buflen += f->val;
 			entry->rule.filterkey = str;
 			break;
+		case AUDIT_PERM:
+			if (f->val & ~15)
+				goto exit_free;
+			break;
 		default:
 			goto exit_free;
 		}
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index efc1b74..1bd8827 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -209,6 +209,54 @@ struct audit_context {
 #endif
 };
 
+#define ACC_MODE(x) ("\004\002\006\006"[(x)&O_ACCMODE])
+static inline int open_arg(int flags, int mask)
+{
+	int n = ACC_MODE(flags);
+	if (flags & (O_TRUNC | O_CREAT))
+		n |= AUDIT_PERM_WRITE;
+	return n & mask;
+}
+
+static int audit_match_perm(struct audit_context *ctx, int mask)
+{
+	unsigned n = ctx->major;
+	switch (audit_classify_syscall(ctx->arch, n)) {
+	case 0:	/* native */
+		if ((mask & AUDIT_PERM_WRITE) &&
+		     audit_match_class(AUDIT_CLASS_WRITE, n))
+			return 1;
+		if ((mask & AUDIT_PERM_READ) &&
+		     audit_match_class(AUDIT_CLASS_READ, n))
+			return 1;
+		if ((mask & AUDIT_PERM_ATTR) &&
+		     audit_match_class(AUDIT_CLASS_CHATTR, n))
+			return 1;
+		return 0;
+	case 1: /* 32bit on biarch */
+		if ((mask & AUDIT_PERM_WRITE) &&
+		     audit_match_class(AUDIT_CLASS_WRITE_32, n))
+			return 1;
+		if ((mask & AUDIT_PERM_READ) &&
+		     audit_match_class(AUDIT_CLASS_READ_32, n))
+			return 1;
+		if ((mask & AUDIT_PERM_ATTR) &&
+		     audit_match_class(AUDIT_CLASS_CHATTR_32, n))
+			return 1;
+		return 0;
+	case 2: /* open */
+		return mask & ACC_MODE(ctx->argv[1]);
+	case 3: /* openat */
+		return mask & ACC_MODE(ctx->argv[2]);
+	case 4: /* socketcall */
+		return ((mask & AUDIT_PERM_WRITE) && ctx->argv[0] == SYS_BIND);
+	case 5: /* execve */
+		return mask & AUDIT_PERM_EXEC;
+	default:
+		return 0;
+	}
+}
+
 /* Determine if any context name data matches a rule's watch data */
 /* Compare a task_struct with an audit_rule.  Return 1 on match, 0
  * otherwise. */
@@ -397,6 +445,9 @@ static int audit_filter_rules(struct task_struct *tsk,
 			/* ignore this field for filtering */
 			result = 1;
 			break;
+		case AUDIT_PERM:
+			result = audit_match_perm(ctx, f->val);
+			break;
 		}
 
 		if (!result)