Make trailing symlink resolution in path_lookupat() iterative
Now the only caller of link_path_walk() that does *not* pass
LOOKUP_PARENT is do_follow_link()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namei.c b/fs/namei.c
index 9e7b18a..a343163 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1588,12 +1588,23 @@
return retval;
}
+static inline int lookup_last(struct nameidata *nd, struct path *path)
+{
+ if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
+ nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+
+ nd->flags &= ~LOOKUP_PARENT;
+ return walk_component(nd, path, &nd->last, nd->last_type,
+ nd->flags & LOOKUP_FOLLOW);
+}
+
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
static int path_lookupat(int dfd, const char *name,
unsigned int flags, struct nameidata *nd)
{
struct file *base = NULL;
- int retval;
+ struct path path;
+ int err;
/*
* Path walking is largely split up into 2 different synchronisation
@@ -1609,23 +1620,55 @@
* be handled by restarting a traditional ref-walk (which will always
* be able to complete).
*/
- retval = path_init(dfd, name, flags, nd, &base);
+ err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);
- if (unlikely(retval))
- return retval;
+ if (unlikely(err))
+ return err;
current->total_link_count = 0;
- retval = link_path_walk(name, nd);
+ err = link_path_walk(name, nd);
+
+ if (!err && !(flags & LOOKUP_PARENT)) {
+ int count = 0;
+ err = lookup_last(nd, &path);
+ while (err > 0) {
+ void *cookie;
+ struct path link = path;
+ struct inode *inode = link.dentry->d_inode;
+
+ if (count++ > 32) {
+ path_put_conditional(&path, nd);
+ path_put(&nd->path);
+ err = -ELOOP;
+ break;
+ }
+ cond_resched();
+ nd->flags |= LOOKUP_PARENT;
+ err = __do_follow_link(&link, nd, &cookie);
+ if (!err)
+ err = lookup_last(nd, &path);
+ if (!IS_ERR(cookie) && inode->i_op->put_link)
+ inode->i_op->put_link(link.dentry, nd, cookie);
+ path_put(&link);
+ }
+ }
if (nd->flags & LOOKUP_RCU) {
/* went all way through without dropping RCU */
- BUG_ON(retval);
+ BUG_ON(err);
if (nameidata_drop_rcu_last(nd))
- retval = -ECHILD;
+ err = -ECHILD;
}
- if (!retval)
- retval = handle_reval_path(nd);
+ if (!err)
+ err = handle_reval_path(nd);
+
+ if (!err && nd->flags & LOOKUP_DIRECTORY) {
+ if (!nd->inode->i_op->lookup) {
+ path_put(&nd->path);
+ return -ENOTDIR;
+ }
+ }
if (base)
fput(base);
@@ -1634,7 +1677,7 @@
path_put(&nd->root);
nd->root.mnt = NULL;
}
- return retval;
+ return err;
}
static int do_path_lookup(int dfd, const char *name,