| Message ID | 20181121195859.10894-1-jannh@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fs: add a comment explaining how MNT_NS_INTERNAL affects mnt_may_suid() | expand |
On Wed, Nov 21, 2018 at 8:59 PM Jann Horn <jannh@google.com> wrote: > commit 380cf5ba6b0a ("fs: Treat foreign mounts as nosuid"), in addition to > the intended effect, also prevented suid execution of memfd files. > (And I think that's a good change.) Ping. Al, can you take this into your tree? fs/namespace.c is your stuff, right? > Signed-off-by: Jann Horn <jannh@google.com> > --- > fs/namespace.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/fs/namespace.c b/fs/namespace.c > index a7f91265ea67..e68488426e42 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -3400,6 +3400,9 @@ bool mnt_may_suid(struct vfsmount *mnt) > * prevents namespaces from trusting potentially unsafe > * suid/sgid bits, file caps, or security labels that originate > * in other namespaces. > + * > + * check_mnt() rejects MNT_NS_INTERNAL mounts; this means that suid > + * execution is blocked for files on internal mounts, e.g. memfds. > */ > return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) && > current_in_userns(mnt->mnt_sb->s_user_ns); > -- > 2.20.0.rc0.387.gc7a69e6b6c-goog >
diff --git a/fs/namespace.c b/fs/namespace.c index a7f91265ea67..e68488426e42 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3400,6 +3400,9 @@ bool mnt_may_suid(struct vfsmount *mnt) * prevents namespaces from trusting potentially unsafe * suid/sgid bits, file caps, or security labels that originate * in other namespaces. + * + * check_mnt() rejects MNT_NS_INTERNAL mounts; this means that suid + * execution is blocked for files on internal mounts, e.g. memfds. */ return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) && current_in_userns(mnt->mnt_sb->s_user_ns);
commit 380cf5ba6b0a ("fs: Treat foreign mounts as nosuid"), in addition to the intended effect, also prevented suid execution of memfd files. (And I think that's a good change.) Signed-off-by: Jann Horn <jannh@google.com> --- fs/namespace.c | 3 +++ 1 file changed, 3 insertions(+)