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authorEric W. Biederman <ebiederm@xmission.com>2017-11-30 02:29:20 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-03-19 10:42:50 +0300
commit5aac93adff9caa5920af52ea1db2a5dc2c1badd9 (patch)
treecf8a87115d53b5394bb470791295553c074a4bc8 /fs/namei.c
parent926b261b1ed523f2e64dfcf33eafc59e0af5bcb4 (diff)
downloadlinux-5aac93adff9caa5920af52ea1db2a5dc2c1badd9.tar.xz
userns: Don't fail follow_automount based on s_user_ns
[ Upstream commit bbc3e471011417598e598707486f5d8814ec9c01 ] 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> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 62a0db6e6725..cbe24e367a70 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1133,9 +1133,6 @@ static int follow_automount(struct path *path, struct nameidata *nd,
path->dentry->d_inode)
return -EISDIR;
- 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;