Re: [PATCH v4 2/4] fanotify: define struct members to hold response decision context

From: Nick Desaulniers
Date: Fri Aug 19 2022 - 13:49:33 EST

On Fri, Aug 19, 2022 at 9:25 AM Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
>
> On 2022-08-10 22:28, kernel test robot wrote:
> > Hi Richard,
> >
> > Thank you for the patch! Perhaps something to improve:
> >
> > [auto build test WARNING on jack-fs/fsnotify]
> > [also build test WARNING on pcmoore-audit/next linus/master v5.19 next-20220810]
> > [If your patch is applied to the wrong git tree, kindly drop us a note.
> > And when submitting patch, we suggest to use '--base' as documented in
> > https://git-scm.com/docs/git-format-patch#_base_tree_information]
> >
> > url: https://github.com/intel-lab-lkp/linux/commits/Richard-Guy-Briggs/fanotify-Allow-user-space-to-pass-back-additional-audit-info/20220810-012825
> > base: https://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git fsnotify
> > config: i386-randconfig-a013 (https://download.01.org/0day-ci/archive/20220810/202208102231.qSUdYAdb-lkp@xxxxxxxxx/config)
> > compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 5f1c7e2cc5a3c07cbc2412e851a7283c1841f520)
> > reproduce (this is a W=1 build):
> > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> > chmod +x ~/bin/make.cross
> > # https://github.com/intel-lab-lkp/linux/commit/a943676abc023c094f05b45f4d61936c567507a2
> > git remote add linux-review https://github.com/intel-lab-lkp/linux
> > git fetch --no-tags linux-review Richard-Guy-Briggs/fanotify-Allow-user-space-to-pass-back-additional-audit-info/20220810-012825
> > git checkout a943676abc023c094f05b45f4d61936c567507a2
> > # save the config file
> > mkdir build_dir && cp config build_dir/.config
> > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash fs/notify/fanotify/
> >
> > If you fix the issue, kindly add following tag where applicable
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> >
> > All warnings (new ones prefixed by >>):
> >
> > >> fs/notify/fanotify/fanotify_user.c:325:35: warning: format specifies type 'unsigned long' but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
>
> Interesting. When I "fix" it, my compiler complains:
>
> fs/notify/fanotify/fanotify_user.c:324:11: warning: format ‘%u’ expects argument of type ‘unsigned int’, but argument 8 has type ‘size_t’ {aka ‘long unsigned int’} [-Wformat=]

The correct format specifier for size_t is %zu. This avoids issues
between ILP32 vs LP64 targets.

>
> > group, fd, response, info_buf, count);
> > ^~~~~
> > include/linux/printk.h:594:38: note: expanded from macro 'pr_debug'
> > no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
> > ~~~ ^~~~~~~~~~~
> > include/linux/printk.h:131:17: note: expanded from macro 'no_printk'
> > printk(fmt, ##__VA_ARGS__); \
> > ~~~ ^~~~~~~~~~~
> > include/linux/printk.h:464:60: note: expanded from macro 'printk'
> > #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
> > ~~~ ^~~~~~~~~~~
> > include/linux/printk.h:436:19: note: expanded from macro 'printk_index_wrap'
> > _p_func(_fmt, ##__VA_ARGS__); \
> > ~~~~ ^~~~~~~~~~~
> > 1 warning generated.
> >
> >
> > vim +325 fs/notify/fanotify/fanotify_user.c
> >
> > 312
> > 313 static int process_access_response(struct fsnotify_group *group,
> > 314 struct fanotify_response *response_struct,
> > 315 const char __user *buf,
> > 316 size_t count)
> > 317 {
> > 318 struct fanotify_perm_event *event;
> > 319 int fd = response_struct->fd;
> > 320 u32 response = response_struct->response;
> > 321 struct fanotify_response_info_header info_hdr;
> > 322 char *info_buf = NULL;
> > 323
> > 324 pr_debug("%s: group=%p fd=%d response=%u buf=%p size=%lu\n", __func__,
> > > 325 group, fd, response, info_buf, count);
> > 326 /*
> > 327 * make sure the response is valid, if invalid we do nothing and either
> > 328 * userspace can send a valid response or we will clean it up after the
> > 329 * timeout
> > 330 */
> > 331 if (response & ~FANOTIFY_RESPONSE_VALID_MASK)
> > 332 return -EINVAL;
> > 333 switch (response & FANOTIFY_RESPONSE_ACCESS) {
> > 334 case FAN_ALLOW:
> > 335 case FAN_DENY:
> > 336 break;
> > 337 default:
> > 338 return -EINVAL;
> > 339 }
> > 340 if ((response & FAN_AUDIT) && !FAN_GROUP_FLAG(group, FAN_ENABLE_AUDIT))
> > 341 return -EINVAL;
> > 342 if (fd < 0)
> > 343 return -EINVAL;
> > 344 if (response & FAN_INFO) {
> > 345 size_t c = count;
> > 346 const char __user *ib = buf;
> > 347
> > 348 if (c <= 0)
> > 349 return -EINVAL;
> > 350 while (c >= sizeof(info_hdr)) {
> > 351 if (copy_from_user(&info_hdr, ib, sizeof(info_hdr)))
> > 352 return -EFAULT;
> > 353 if (info_hdr.pad != 0)
> > 354 return -EINVAL;
> > 355 if (c < info_hdr.len)
> > 356 return -EINVAL;
> > 357 switch (info_hdr.type) {
> > 358 case FAN_RESPONSE_INFO_AUDIT_RULE:
> > 359 break;
> > 360 case FAN_RESPONSE_INFO_NONE:
> > 361 default:
> > 362 return -EINVAL;
> > 363 }
> > 364 c -= info_hdr.len;
> > 365 ib += info_hdr.len;
> > 366 }
> > 367 if (c != 0)
> > 368 return -EINVAL;
> > 369 /* Simplistic check for now */
> > 370 if (count != sizeof(struct fanotify_response_info_audit_rule))
> > 371 return -EINVAL;
> > 372 info_buf = kmalloc(sizeof(struct fanotify_response_info_audit_rule),
> > 373 GFP_KERNEL);
> > 374 if (!info_buf)
> > 375 return -ENOMEM;
> > 376 if (copy_from_user(info_buf, buf, count))
> > 377 return -EFAULT;
> > 378 }
> > 379 spin_lock(&group->notification_lock);
> > 380 list_for_each_entry(event, &group->fanotify_data.access_list,
> > 381 fae.fse.list) {
> > 382 if (event->fd != fd)
> > 383 continue;
> > 384
> > 385 list_del_init(&event->fae.fse.list);
> > 386 /* finish_permission_event() eats info_buf */
> > 387 finish_permission_event(group, event, response_struct,
> > 388 count, info_buf);
> > 389 wake_up(&group->fanotify_data.access_waitq);
> > 390 return 0;
> > 391 }
> > 392 spin_unlock(&group->notification_lock);
> > 393
> > 394 return -ENOENT;
> > 395 }
> > 396
> >
> > --
> > 0-DAY CI Kernel Test Service
> > https://01.org/lkp
> >
>
> - RGB
>
> --
> Richard Guy Briggs <rgb@xxxxxxxxxx>
> Sr. S/W Engineer, Kernel Security, Base Operating Systems
> Remote, Ottawa, Red Hat Canada
> IRC: rgb, SunRaycer
> Voice: +1.647.777.2635, Internal: (81) 32635
>
>


--
Thanks,
~Nick Desaulniers