audit: set the name_len in audit_inode for parent lookups

Currently, this gets set mostly by happenstance when we call into
audit_inode_child. While that might be a little more efficient, it seems
wrong. If the syscall ends up failing before audit_inode_child ever gets
called, then you'll have an audit_names record that shows the full path
but has the parent inode info attached.

Fix this by passing in a parent flag when we call audit_inode that gets
set to the value of LOOKUP_PARENT. We can then fix up the pathname for
the audit entry correctly from the get-go.

While we're at it, clean up the no-op macro for audit_inode in the
!CONFIG_AUDITSYSCALL case.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 60 insertions, 12 deletions

diff --git a/kernel/audit.h b/kernel/audit.h
index 9eb3d79..163b9a5 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -78,6 +78,7 @@ 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_uid_comparator(kuid_t left, u32 op, kuid_t right);
 extern int audit_gid_comparator(kgid_t left, u32 op, kgid_t right);
+extern int parent_len(const char *path);
 extern int audit_compare_dname_path(const char *dname, const char *path,
 				    int *dirlen);
 extern struct sk_buff *	    audit_make_reply(int pid, int seq, int type,
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index c4bcdba..71bb135 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1298,6 +1298,36 @@ int audit_gid_comparator(kgid_t left, u32 op, kgid_t right)
 	}
 }
 
+/**
+ * parent_len - find the length of the parent portion of a pathname
+ * @path: pathname of which to determine length
+ */
+int parent_len(const char *path)
+{
+	int plen;
+	const char *p;
+
+	plen = strlen(path);
+
+	if (plen == 0)
+		return plen;
+
+	/* disregard trailing slashes */
+	p = path + plen - 1;
+	while ((*p == '/') && (p > path))
+		p--;
+
+	/* walk backward until we find the next slash or hit beginning */
+	while ((*p != '/') && (p > path))
+		p--;
+
+	/* did we find a slash? Then increment to include it in path */
+	if (*p == '/')
+		p++;
+
+	return p - path;
+}
+
 /* Compare given dentry name with last component in given path,
  * return of 0 indicates a match. */
 int audit_compare_dname_path(const char *dname, const char *path,
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 19b232f..b87b289 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2135,13 +2135,13 @@ static void audit_copy_inode(struct audit_names *name, const struct dentry *dent
 }
 
 /**
- * audit_inode - store the inode and device from a lookup
+ * __audit_inode - store the inode and device from a lookup
  * @name: name being audited
  * @dentry: dentry being audited
- *
- * Called from fs/namei.c:path_lookup().
+ * @parent: does this dentry represent the parent?
  */
-void __audit_inode(const char *name, const struct dentry *dentry)
+void __audit_inode(const char *name, const struct dentry *dentry,
+		   unsigned int parent)
 {
 	struct audit_context *context = current->audit_context;
 	const struct inode *inode = dentry->d_inode;
@@ -2154,19 +2154,38 @@ void __audit_inode(const char *name, const struct dentry *dentry)
 		goto out_alloc;
 
 	list_for_each_entry_reverse(n, &context->names_list, list) {
-		if (n->name == name)
-			goto out;
+		/* does the name pointer match? */
+		if (n->name != name)
+			continue;
+
+		/* match the correct record type */
+		if (parent) {
+			if (n->type == AUDIT_TYPE_PARENT ||
+			    n->type == AUDIT_TYPE_UNKNOWN)
+				goto out;
+		} else {
+			if (n->type != AUDIT_TYPE_PARENT)
+				goto out;
+		}
 	}
 
 out_alloc:
-	/* unable to find the name from a previous getname() */
+	/* unable to find the name from a previous getname(). Allocate a new
+	 * anonymous entry.
+	 */
 	n = audit_alloc_name(context, AUDIT_TYPE_NORMAL);
 	if (!n)
 		return;
 out:
+	if (parent) {
+		n->name_len = n->name ? parent_len(n->name) : AUDIT_NAME_FULL;
+		n->type = AUDIT_TYPE_PARENT;
+	} else {
+		n->name_len = AUDIT_NAME_FULL;
+		n->type = AUDIT_TYPE_NORMAL;
+	}
 	handle_path(dentry);
 	audit_copy_inode(n, dentry, inode);
-	n->type = AUDIT_TYPE_NORMAL;
 }
 
 /**
@@ -2190,7 +2209,6 @@ void __audit_inode_child(const struct inode *parent,
 	const struct inode *inode = dentry->d_inode;
 	const char *dname = dentry->d_name.name;
 	struct audit_names *n;
-	int dirlen = 0;
 
 	if (!context->in_syscall)
 		return;
@@ -2204,8 +2222,7 @@ void __audit_inode_child(const struct inode *parent,
 			continue;
 
 		if (n->ino == parent->i_ino &&
-		    !audit_compare_dname_path(dname, n->name, &dirlen)) {
-			n->name_len = dirlen; /* update parent data in place */
+		    !audit_compare_dname_path(dname, n->name, NULL)) {
 			found_parent = n->name;
 			goto add_names;
 		}
@@ -2218,7 +2235,7 @@ void __audit_inode_child(const struct inode *parent,
 
 		/* strcmp() is the more likely scenario */
 		if (!strcmp(dname, n->name) ||
-		     !audit_compare_dname_path(dname, n->name, &dirlen)) {
+		     !audit_compare_dname_path(dname, n->name, NULL)) {
 			if (inode)
 				audit_copy_inode(n, dentry, inode);
 			else