[PATCH v3 20/21] 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. Signed-off-by: Seth ForsheeAcked-by: Serge Hallyn Acked-by: Miklos Szeredi --- fs/fuse/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index ecba75bf6640..1a6c5af49608 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1015,7 +1015,7 @@ int fuse_allow_current_process(struct fuse_conn *fc) const struct cred *cred; if (fc->flags & FUSE_ALLOW_OTHER) - return 1; + return current_in_userns(fc->user_ns); cred = current_cred(); if (uid_eq(cred->euid, fc->user_id) && -- 1.9.1
[PATCH v3 20/21] 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. Signed-off-by: Seth Forshee Acked-by: Serge Hallyn Acked-by: Miklos Szeredi --- fs/fuse/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index ecba75bf6640..1a6c5af49608 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1015,7 +1015,7 @@ int fuse_allow_current_process(struct fuse_conn *fc) const struct cred *cred; if (fc->flags & FUSE_ALLOW_OTHER) - return 1; + return current_in_userns(fc->user_ns); cred = current_cred(); if (uid_eq(cred->euid, fc->user_id) && -- 1.9.1