[PATCH] new predicate - AUDIT_FILETYPE

Argument is S_IF... | <index>, where index is normally 0 or 1.
Triggers if chosen element of ctx->names[] is present and the
mode of object in question matches the upper bits of argument.
I.e. for things like "is the argument of that chmod a directory",
etc.

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

Author: Al Viro

include/linux/audit.h

@@ -209,6 +209,7 @@
 #define AUDIT_WATCH	105
 #define AUDIT_PERM	106
 #define AUDIT_DIR	107
+#define AUDIT_FILETYPE	108
 
 #define AUDIT_ARG0      200
 #define AUDIT_ARG1      (AUDIT_ARG0+1)

kernel/auditfilter.c

@@ -478,6 +478,10 @@ static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
 			if (f->val & ~15)
 				goto exit_free;
 			break;
+		case AUDIT_FILETYPE:
+			if ((f->val & ~S_IFMT) > S_IFMT)
+				goto exit_free;
+			break;
 		case AUDIT_INODE:
 			err = audit_to_inode(&entry->rule, f);
 			if (err)
@@ -649,6 +653,10 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
 			if (f->val & ~15)
 				goto exit_free;
 			break;
+		case AUDIT_FILETYPE:
+			if ((f->val & ~S_IFMT) > S_IFMT)
+				goto exit_free;
+			break;
 		default:
 			goto exit_free;
 		}

kernel/auditsc.c

@@ -280,6 +280,19 @@ static int audit_match_perm(struct audit_context *ctx, int mask)
 	}
 }
 
+static int audit_match_filetype(struct audit_context *ctx, int which)
+{
+	unsigned index = which & ~S_IFMT;
+	mode_t mode = which & S_IFMT;
+	if (index >= ctx->name_count)
+		return 0;
+	if (ctx->names[index].ino == -1)
+		return 0;
+	if ((ctx->names[index].mode ^ mode) & S_IFMT)
+		return 0;
+	return 1;
+}
+
 /*
  * We keep a linked list of fixed-sized (31 pointer) arrays of audit_chunk *;
  * ->first_trees points to its beginning, ->trees - to the current end of data.
@@ -589,6 +602,9 @@ static int audit_filter_rules(struct task_struct *tsk,
 		case AUDIT_PERM:
 			result = audit_match_perm(ctx, f->val);
 			break;
+		case AUDIT_FILETYPE:
+			result = audit_match_filetype(ctx, f->val);
+			break;
 		}
 
 		if (!result)