Re: [PATCH] kernel: prevent submission of creds with higher privileges inside container
From: kbuild test robot
Date: Tue Sep 11 2018 - 02:54:24 EST
Hi Xin,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v4.19-rc3 next-20180910]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/My-Name/kernel-prevent-submission-of-creds-with-higher-privileges-inside-container/20180911-135856
config: x86_64-randconfig-x019-201836 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
All errors (new ones prefixed by >>):
kernel/cred.c: In function 'commit_creds':
>> kernel/cred.c:428:40: error: 'PROC_UTS_INIT_INO' undeclared (first use in this function)
if (task->nsproxy->uts_ns->ns.inum != PROC_UTS_INIT_INO ||
^~~~~~~~~~~~~~~~~
kernel/cred.c:428:40: note: each undeclared identifier is reported only once for each function it appears in
>> kernel/cred.c:429:23: error: dereferencing pointer to incomplete type 'struct ipc_namespace'
task->nsproxy->ipc_ns->ns.inum != PROC_IPC_INIT_INO ||
^~
>> kernel/cred.c:429:36: error: 'PROC_IPC_INIT_INO' undeclared (first use in this function); did you mean 'PROC_UTS_INIT_INO'?
task->nsproxy->ipc_ns->ns.inum != PROC_IPC_INIT_INO ||
^~~~~~~~~~~~~~~~~
PROC_UTS_INIT_INO
>> kernel/cred.c:430:23: error: dereferencing pointer to incomplete type 'struct mnt_namespace'
task->nsproxy->mnt_ns->ns.inum != 0xF0000000U ||
^~
>> kernel/cred.c:431:49: error: 'PROC_PID_INIT_INO' undeclared (first use in this function); did you mean 'PROC_IPC_INIT_INO'?
task->nsproxy->pid_ns_for_children->ns.inum != PROC_PID_INIT_INO ||
^~~~~~~~~~~~~~~~~
PROC_IPC_INIT_INO
>> kernel/cred.c:433:27: error: 'PROC_USER_INIT_INO' undeclared (first use in this function); did you mean 'PROC_UTS_INIT_INO'?
old->user_ns->ns.inum != PROC_USER_INIT_INO ||
^~~~~~~~~~~~~~~~~~
PROC_UTS_INIT_INO
>> kernel/cred.c:434:26: error: dereferencing pointer to incomplete type 'struct cgroup_namespace'
task->nsproxy->cgroup_ns->ns.inum != PROC_CGROUP_INIT_INO) {
^~
>> kernel/cred.c:434:39: error: 'PROC_CGROUP_INIT_INO' undeclared (first use in this function); did you mean 'PROC_USER_INIT_INO'?
task->nsproxy->cgroup_ns->ns.inum != PROC_CGROUP_INIT_INO) {
^~~~~~~~~~~~~~~~~~~~
PROC_USER_INIT_INO
vim +/PROC_UTS_INIT_INO +428 kernel/cred.c
408
409 /**
410 * commit_creds - Install new credentials upon the current task
411 * @new: The credentials to be assigned
412 *
413 * Install a new set of credentials to the current task, using RCU to replace
414 * the old set. Both the objective and the subjective credentials pointers are
415 * updated. This function may not be called if the subjective credentials are
416 * in an overridden state.
417 *
418 * This function eats the caller's reference to the new credentials.
419 *
420 * Always returns 0 thus allowing this function to be tail-called at the end
421 * of, say, sys_setgid().
422 */
423 int commit_creds(struct cred *new)
424 {
425 struct task_struct *task = current;
426 const struct cred *old = task->real_cred;
427
> 428 if (task->nsproxy->uts_ns->ns.inum != PROC_UTS_INIT_INO ||
> 429 task->nsproxy->ipc_ns->ns.inum != PROC_IPC_INIT_INO ||
> 430 task->nsproxy->mnt_ns->ns.inum != 0xF0000000U ||
> 431 task->nsproxy->pid_ns_for_children->ns.inum != PROC_PID_INIT_INO ||
432 task->nsproxy->net_ns->ns.inum != 0xF0000075U ||
> 433 old->user_ns->ns.inum != PROC_USER_INIT_INO ||
> 434 task->nsproxy->cgroup_ns->ns.inum != PROC_CGROUP_INIT_INO) {
435 if (new->uid.val < old->uid.val || new->gid.val < old->gid.val
436 || new->cap_bset.cap[0] > old->cap_bset.cap[0])
437 return 0;
438 }
439
440 kdebug("commit_creds(%p{%d,%d})", new,
441 atomic_read(&new->usage),
442 read_cred_subscribers(new));
443
444 BUG_ON(task->cred != old);
445 #ifdef CONFIG_DEBUG_CREDENTIALS
446 BUG_ON(read_cred_subscribers(old) < 2);
447 validate_creds(old);
448 validate_creds(new);
449 #endif
450 BUG_ON(atomic_read(&new->usage) < 1);
451
452 get_cred(new); /* we will require a ref for the subj creds too */
453
454 /* dumpability changes */
455 if (!uid_eq(old->euid, new->euid) ||
456 !gid_eq(old->egid, new->egid) ||
457 !uid_eq(old->fsuid, new->fsuid) ||
458 !gid_eq(old->fsgid, new->fsgid) ||
459 !cred_cap_issubset(old, new)) {
460 if (task->mm)
461 set_dumpable(task->mm, suid_dumpable);
462 task->pdeath_signal = 0;
463 smp_wmb();
464 }
465
466 /* alter the thread keyring */
467 if (!uid_eq(new->fsuid, old->fsuid))
468 key_fsuid_changed(task);
469 if (!gid_eq(new->fsgid, old->fsgid))
470 key_fsgid_changed(task);
471
472 /* do it
473 * RLIMIT_NPROC limits on user->processes have already been checked
474 * in set_user().
475 */
476 alter_cred_subscribers(new, 2);
477 if (new->user != old->user)
478 atomic_inc(&new->user->processes);
479 rcu_assign_pointer(task->real_cred, new);
480 rcu_assign_pointer(task->cred, new);
481 if (new->user != old->user)
482 atomic_dec(&old->user->processes);
483 alter_cred_subscribers(old, -2);
484
485 /* send notifications */
486 if (!uid_eq(new->uid, old->uid) ||
487 !uid_eq(new->euid, old->euid) ||
488 !uid_eq(new->suid, old->suid) ||
489 !uid_eq(new->fsuid, old->fsuid))
490 proc_id_connector(task, PROC_EVENT_UID);
491
492 if (!gid_eq(new->gid, old->gid) ||
493 !gid_eq(new->egid, old->egid) ||
494 !gid_eq(new->sgid, old->sgid) ||
495 !gid_eq(new->fsgid, old->fsgid))
496 proc_id_connector(task, PROC_EVENT_GID);
497
498 /* release the old obj and subj refs both */
499 put_cred(old);
500 put_cred(old);
501 return 0;
502 }
503 EXPORT_SYMBOL(commit_creds);
504
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