@@ -1567,6 +1567,7 @@ static void check_unsafe_exec(struct linux_binprm *bprm)
static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
{
/* Handle suid and sgid on files */
+ struct user_namespace *mnt_userns;
struct inode *inode;
unsigned int mode;
kuid_t uid;
@@ -1583,13 +1584,15 @@ static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
if (!(mode & (S_ISUID|S_ISGID)))
return;
+ mnt_userns = mnt_user_ns(file->f_path.mnt);
+
/* Be careful if suid/sgid is set */
inode_lock(inode);
/* reload atomically mode/uid/gid now that lock held */
mode = inode->i_mode;
- uid = inode->i_uid;
- gid = inode->i_gid;
+ uid = i_uid_into_mnt(mnt_userns, inode);
+ gid = i_gid_into_mnt(mnt_userns, inode);
inode_unlock(inode);
/* We ignore suid/sgid if there are no mappings for them in the ns */
When executing a setuid binary the kernel will verify in bprm_fill_uid() that the inode has a mapping in the caller's user namespace before setting the callers uid and gid. Let bprm_fill_uid() handle idmapped mounts. If the inode is accessed through an idmapped mount it is mapped according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> --- /* v2 */ unchanged /* v3 */ unchanged /* v4 */ - Serge Hallyn <serge@hallyn.com>: - Use "mnt_userns" to refer to a vfsmount's userns everywhere to make terminology consistent. --- fs/exec.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)