[PATCH] vfs: Fix O_NOFOLLOW behavior for paths with trailing slashes

From: Jan Kara
Date: Thu May 13 2010 - 06:53:29 EST


According to specification
mkdir d; ln -s d a; open("a/", O_NOFOLLOW | O_RDONLY)
should return success but currently it did return ELOOP. Fix the code to ignore
O_NOFOLLOW in case the provided path has trailing slashes. This is a regression
caused by path lookup cleanup patch series.

CC: stable@xxxxxxxxxx
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Reported-by: tolzmann@xxxxxxxxxxxxx
Acked-by: Miklos Szeredi <mszeredi@xxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
Since Al doesn't seem to react for a few days and this is kind of nasty bug,
I'm sending it directly...

fs/namei.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index a7dce91..16df727 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1641,7 +1641,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
if (nd->last.name[nd->last.len]) {
if (open_flag & O_CREAT)
goto exit;
- nd->flags |= LOOKUP_DIRECTORY;
+ nd->flags |= LOOKUP_DIRECTORY | LOOKUP_FOLLOW;
}

/* just plain open? */
@@ -1830,6 +1830,8 @@ reval:
}
if (open_flag & O_DIRECTORY)
nd.flags |= LOOKUP_DIRECTORY;
+ if (!(open_flag & O_NOFOLLOW))
+ nd.flags |= LOOKUP_FOLLOW;
filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
while (unlikely(!filp)) { /* trailing symlink */
struct path holder;
@@ -1837,7 +1839,7 @@ reval:
void *cookie;
error = -ELOOP;
/* S_ISDIR part is a temporary automount kludge */
- if ((open_flag & O_NOFOLLOW) && !S_ISDIR(inode->i_mode))
+ if (!(nd.flags & LOOKUP_FOLLOW) && !S_ISDIR(inode->i_mode))
goto exit_dput;
if (count++ == 32)
goto exit_dput;
--
1.6.4.2

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