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authorSeth Forshee <seth.forshee@canonical.com>2017-12-22 15:32:33 +0100
committerMiklos Szeredi <mszeredi@redhat.com>2018-03-20 17:11:44 +0100
commit73f03c2b4b527346778c711c2734dbff3442b139 (patch)
tree8b6b777b9a3ce6c422910c46b414ea356f20d191 /fs/fuse
parent8cb08329b0809453722bc12aa912be34355bcb66 (diff)
fuse: Restrict allow_other to the superblock's namespace or a descendant
Unprivileged users are normally restricted from mounting with the allow_other option by system policy, but this could be bypassed for a mount done with user namespace root permissions. In such cases allow_other should not allow users outside the userns to access the mount as doing so would give the unprivileged user the ability to manipulate processes it would otherwise be unable to manipulate. Restrict allow_other to apply to users in the same userns used at mount or a descendant of that namespace. Also export current_in_userns() for use by fuse when built as a module. Reviewed-by: Serge Hallyn <serge@hallyn.com> Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: Dongsu Park <dongsu@kinvolk.io> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/fuse')
-rw-r--r--fs/fuse/dir.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index cf8a1cd7a62e..fa4009761a7a 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1030,7 +1030,7 @@ int fuse_allow_current_process(struct fuse_conn *fc)
const struct cred *cred;
if (fc->allow_other)
- return 1;
+ return current_in_userns(fc->user_ns);
cred = current_cred();
if (uid_eq(cred->euid, fc->user_id) &&