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authorEric W. Biederman <ebiederm@xmission.com>2017-11-29 17:29:20 -0600
committerEric W. Biederman <ebiederm@xmission.com>2017-11-30 17:47:20 -0600
commitbbc3e471011417598e598707486f5d8814ec9c01 (patch)
tree4a1d964a20a97ab29cb0341035d4b94e77cd15a6 /fs/namei.c
parent4fbd8d194f06c8a3fd2af1ce560ddb31f7ec8323 (diff)
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userns: Don't fail follow_automount based on s_user_ns
When vfs_submount was added the test to limit automounts from filesystems that with s_user_ns != &init_user_ns accidentially left in follow_automount. The test was never about any security concerns and was always about how do we implement this for filesystems whose s_user_ns != &init_user_ns. At the moment this check makes no difference as there are no filesystems that both set FS_USERNS_MOUNT and implement d_automount. Remove this check now while I am thinking about it so there will not be odd booby traps for someone who does want to make this combination work. vfs_submount still needs improvements to allow this combination to work, and vfs_submount contains a check that presents a warning. The autofs4 filesystem could be modified to set FS_USERNS_MOUNT and it would need not work on this code path, as userspace performs the mounts. Fixes: 93faccbbfa95 ("fs: Better permission checking for submounts") Fixes: aeaa4a79ff6a ("fs: Call d_automount with the filesystems creds") Acked-by: Ian Kent <raven@themaw.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c3
1 files changed, 0 insertions, 3 deletions
diff --git a/fs/namei.c b/fs/namei.c
index f0c7a7b9b6ca..f47118ed36e7 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1142,9 +1142,6 @@ static int follow_automount(struct path *path, struct nameidata *nd,
return -ENOENT;
}
- if (path->dentry->d_sb->s_user_ns != &init_user_ns)
- return -EACCES;
-
nd->total_link_count++;
if (nd->total_link_count >= 40)
return -ELOOP;