Re: [PATCH v5 17/24] landlock: Add LANDLOCK_RESTRICT_SELF_QUIET_SUBDOMAINS

kernel test robot
2025-01-31T20:29:13Z

Hi Mickaël,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 69e858e0b8b2ea07759e995aa383e8780d9d140c]

url: https://github.com/intel-lab-lkp/linux/commits/Micka-l-Sala-n/lsm-Add-audit_log_lsm_data-helper/20250201-004434
base: 69e858e0b8b2ea07759e995aa383e8780d9d140c
patch link: https://lore.kernel.org/r/20250131163059.1139617-18-mic%40digikod.net
patch subject: [PATCH v5 17/24] landlock: Add LANDLOCK_RESTRICT_SELF_QUIET_SUBDOMAINS
config: x86_64-buildonly-randconfig-002-20250201 (https://download.01.org/0day-ci/archive/20250201/202502010411.lOcXpnOG-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250201/202502010411.lOcXpnOG-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202502010411.lOcXpnOG-lkp@intel.com/

All warnings (new ones prefixed by >>):

security/landlock/syscalls.c: In function '__do_sys_landlock_restrict_self':
>> security/landlock/syscalls.c:469:24: warning: variable 'is_quiet_subdomains' set but not used [-Wunused-but-set-variable]
469 | bool is_quiet, is_quiet_subdomains,
| ^~~~~~~~~~~~~~~~~~~
security/landlock/syscalls.c:469:14: warning: variable 'is_quiet' set but not used [-Wunused-but-set-variable]
469 | bool is_quiet, is_quiet_subdomains,
| ^~~~~~~~

vim +/is_quiet_subdomains +469 security/landlock/syscalls.c

435
436 /**
437 * sys_landlock_restrict_self - Enforce a ruleset on the calling thread
438 *
439 * @ruleset_fd: File descriptor tied to the ruleset to merge with the target.
440 * @flags: Supported values:
441 *
442 * - %LANDLOCK_RESTRICT_SELF_QUIET
443 * - %LANDLOCK_RESTRICT_SELF_QUIET_SUBDOMAINS
444 *
445 * This system call enables to enforce a Landlock ruleset on the current
446 * thread. Enforcing a ruleset requires that the task has %CAP_SYS_ADMIN in its
447 * namespace or is running with no_new_privs. This avoids scenarios where
448 * unprivileged tasks can affect the behavior of privileged children.
449 *
450 * Possible returned errors are:
451 *
452 * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
453 * - %EINVAL: @flags contains an unknown bit.
454 * - %EBADF: @ruleset_fd is not a file descriptor for the current thread;
455 * - %EBADFD: @ruleset_fd is not a ruleset file descriptor;
456 * - %EPERM: @ruleset_fd has no read access to the underlying ruleset, or the
457 * current thread is not running with no_new_privs, or it doesn't have
458 * %CAP_SYS_ADMIN in its namespace.
459 * - %E2BIG: The maximum number of stacked rulesets is reached for the current
460 * thread.
461 */
462 SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
463 flags)
464 {
465 struct landlock_ruleset *new_dom,
466 *ruleset __free(landlock_put_ruleset) = NULL;
467 struct cred *new_cred;
468 struct landlock_cred_security *new_llcred;
> 469 bool is_quiet, is_quiet_subdomains,
470 __maybe_unused inherits_quiet_subdomains;
471
472 if (!is_initialized())
473 return -EOPNOTSUPP;
474
475 /*
476 * Similar checks as for seccomp(2), except that an -EPERM may be
477 * returned.
478 */
479 if (!task_no_new_privs(current) &&
480 !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
481 return -EPERM;
482
483 if ((flags | LANDLOCK_MASK_RESTRICT_SELF) !=
484 LANDLOCK_MASK_RESTRICT_SELF)
485 return -EINVAL;
486
487 is_quiet = !!(flags & LANDLOCK_RESTRICT_SELF_QUIET);
488 is_quiet_subdomains =
489 !!(flags & LANDLOCK_RESTRICT_SELF_QUIET_SUBDOMAINS);
490
491 /* Gets and checks the ruleset. */
492 ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_READ);
493 if (IS_ERR(ruleset))
494 return PTR_ERR(ruleset);
495
496 /* Prepares new credentials. */
497 new_cred = prepare_creds();
498 if (!new_cred)
499 return -ENOMEM;
500
501 new_llcred = landlock_cred(new_cred);
502
503 /*
504 * There is no possible race condition while copying and manipulating
505 * the current credentials because they are dedicated per thread.
506 */
507 new_dom = landlock_merge_ruleset(new_llcred->domain, ruleset);
508 if (IS_ERR(new_dom)) {
509 abort_creds(new_cred);
510 return PTR_ERR(new_dom);
511 }
512

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