user/sven/linux.git/fs/proc, branch v4.4.272

proc: Check /proc/$pid/attr/ writes against file opener

2021-06-03T06:22:04Z

commit bfb819ea20ce8bbeeba17e1a6418bf8bda91fc28 upstream. Fix another "confused deputy" weakness[1]. Writes to /proc/$pid/attr/ files need to check the opener credentials, since these fds do not transition state across execve(). Without this, it is possible to trick another process (which may have different credentials) to write to its own /proc/$pid/attr/ files, leading to unexpected and possibly exploitable behaviors. [1] https://www.kernel.org/doc/html/latest/security/credentials.html?highlight=confused#open-file-credentials Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

proc: don't allow async path resolution of /proc/self components

2020-12-02T07:29:27Z

[ Upstream commit 8d4c3e76e3be11a64df95ddee52e99092d42fc19 ] If this is attempted by a kthread, then return -EOPNOTSUPP as we don't currently support that. Once we can get task_pid_ptr() doing the right thing, then this can go away again. Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

proc: Use new_inode not new_inode_pseudo

2020-06-20T08:23:18Z

commit ef1548adada51a2f32ed7faef50aa465e1b4c5da upstream. Recently syzbot reported that unmounting proc when there is an ongoing inotify watch on the root directory of proc could result in a use after free when the watch is removed after the unmount of proc when the watcher exits. Commit 69879c01a0c3 ("proc: Remove the now unnecessary internal mount of proc") made it easier to unmount proc and allowed syzbot to see the problem, but looking at the code it has been around for a long time. Looking at the code the fsnotify watch should have been removed by fsnotify_sb_delete in generic_shutdown_super. Unfortunately the inode was allocated with new_inode_pseudo instead of new_inode so the inode was not on the sb->s_inodes list. Which prevented fsnotify_unmount_inodes from finding the inode and removing the watch as well as made it so the "VFS: Busy inodes after unmount" warning could not find the inodes to warn about them. Make all of the inodes in proc visible to generic_shutdown_super, and fsnotify_sb_delete by using new_inode instead of new_inode_pseudo. The only functional difference is that new_inode places the inodes on the sb->s_inodes list. I wrote a small test program and I can verify that without changes it can trigger this issue, and by replacing new_inode_pseudo with new_inode the issues goes away. Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/000000000000d788c905a7dfa3f4@google.com Reported-by: syzbot+7d2debdcdb3cb93c1e5e@syzkaller.appspotmail.com Fixes: 0097875bd415 ("proc: Implement /proc/thread-self to point at the directory of the current thread") Fixes: 021ada7dff22 ("procfs: switch /proc/self away from proc_dir_entry") Fixes: 51f0885e5415 ("vfs,proc: guarantee unique inodes in /proc") Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman

mm/page_alloc.c: calculate 'available' memory in a separate function

2020-01-23T07:18:35Z

commit d02bd27bd33dd7e8d22594cd568b81be0cb584cd upstream. Add a new field, VIRTIO_BALLOON_S_AVAIL, to virtio_balloon memory statistics protocol, corresponding to 'Available' in /proc/meminfo. It indicates to the hypervisor how big the balloon can be inflated without pushing the guest system to swap. This metric would be very useful in VM orchestration software to improve memory management of different VMs under overcommit. This patch (of 2): Factor out calculation of the available memory counter into a separate exportable function, in order to be able to use it in other parts of the kernel. In particular, it appears a relevant metric to report to the hypervisor via virtio-balloon statistics interface (in a followup patch). Signed-off-by: Igor Redko Signed-off-by: Denis V. Lunev Reviewed-by: Roman Kagan Cc: Michael S. Tsirkin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 4.4 as dependency of commit a1078e821b60 "xen: let alloc_xenballooned_pages() fail if not enough memory free"] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman

fs/proc/array.c: allow reporting eip/esp for all coredumping threads

2019-12-21T09:35:07Z

commit cb8f381f1613cafe3aec30809991cd56e7135d92 upstream. 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in /proc/PID/stat") stopped reporting eip/esp and fd7d56270b52 ("fs/proc: Report eip/esp in /prod/PID/stat for coredumping") reintroduced the feature to fix a regression with userspace core dump handlers (such as minicoredumper). Because PF_DUMPCORE is only set for the primary thread, this didn't fix the original problem for secondary threads. Allow reporting the eip/esp for all threads by checking for PF_EXITING as well. This is set for all the other threads when they are killed. coredump_wait() waits for all the tasks to become inactive before proceeding to invoke a core dumper. Link: http://lkml.kernel.org/r/87y32p7i7a.fsf@linutronix.de Link: http://lkml.kernel.org/r/20190522161614.628-1-jlu@pengutronix.de Fixes: fd7d56270b526ca3 ("fs/proc: Report eip/esp in /prod/PID/stat for coredumping") Signed-off-by: John Ogness Reported-by: Jan Luebbe Tested-by: Jan Luebbe Cc: Alexey Dobriyan Cc: Andy Lutomirski Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: zhangyi (F) Signed-off-by: Greg Kroah-Hartman

proc: fix coredump vs read /proc/*/stat race

2019-12-21T09:35:06Z

commit 8bb2ee192e482c5d500df9f2b1b26a560bd3026f upstream. do_task_stat() accesses IP and SP of a task without bumping reference count of a stack (which became an entity with independent lifetime at some point). Steps to reproduce: #include #include #include #include #include #include #include #include int main(void) { setrlimit(RLIMIT_CORE, &(struct rlimit){}); while (1) { char buf[64]; char buf2[4096]; pid_t pid; int fd; pid = fork(); if (pid == 0) { *(volatile int *)0 = 0; } snprintf(buf, sizeof(buf), "/proc/%u/stat", pid); fd = open(buf, O_RDONLY); read(fd, buf2, sizeof(buf2)); close(fd); waitpid(pid, NULL, 0); } return 0; } BUG: unable to handle kernel paging request at 0000000000003fd8 IP: do_task_stat+0x8b4/0xaf0 PGD 800000003d73e067 P4D 800000003d73e067 PUD 3d558067 PMD 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 1417 Comm: a.out Not tainted 4.15.0-rc8-dirty #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc27 04/01/2014 RIP: 0010:do_task_stat+0x8b4/0xaf0 Call Trace: proc_single_show+0x43/0x70 seq_read+0xe6/0x3b0 __vfs_read+0x1e/0x120 vfs_read+0x84/0x110 SyS_read+0x3d/0xa0 entry_SYSCALL_64_fastpath+0x13/0x6c RIP: 0033:0x7f4d7928cba0 RSP: 002b:00007ffddb245158 EFLAGS: 00000246 Code: 03 b7 a0 01 00 00 4c 8b 4c 24 70 4c 8b 44 24 78 4c 89 74 24 18 e9 91 f9 ff ff f6 45 4d 02 0f 84 fd f7 ff ff 48 8b 45 40 48 89 ef <48> 8b 80 d8 3f 00 00 48 89 44 24 20 e8 9b 97 eb ff 48 89 44 24 RIP: do_task_stat+0x8b4/0xaf0 RSP: ffffc90000607cc8 CR2: 0000000000003fd8 John Ogness said: for my tests I added an else case to verify that the race is hit and correctly mitigated. Link: http://lkml.kernel.org/r/20180116175054.GA11513@avx2 Signed-off-by: Alexey Dobriyan Reported-by: "Kohli, Gaurav" Tested-by: John Ogness Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Oleg Nesterov Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: zhangyi (F) Signed-off-by: Greg Kroah-Hartman

fs/proc: Report eip/esp in /prod/PID/stat for coredumping

2019-12-21T09:35:06Z

commit fd7d56270b526ca3ed0c224362e3c64a0f86687a upstream. Commit 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in /proc/PID/stat") stopped reporting eip/esp because it is racy and dangerous for executing tasks. The comment adds: As far as I know, there are no use programs that make any material use of these fields, so just get rid of them. However, existing userspace core-dump-handler applications (for example, minicoredumper) are using these fields since they provide an excellent cross-platform interface to these valuable pointers. So that commit introduced a user space visible regression. Partially revert the change and make the readout possible for tasks with the proper permissions and only if the target task has the PF_DUMPCORE flag set. Fixes: 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in> /proc/PID/stat") Reported-by: Marco Felsch Signed-off-by: John Ogness Reviewed-by: Andy Lutomirski Cc: Tycho Andersen Cc: Kees Cook Cc: Peter Zijlstra Cc: Brian Gerst Cc: stable@vger.kernel.org Cc: Tetsuo Handa Cc: Borislav Petkov Cc: Al Viro Cc: Linux API Cc: Andrew Morton Cc: Linus Torvalds Link: http://lkml.kernel.org/r/87poatfwg6.fsf@linutronix.de Signed-off-by: Thomas Gleixner [ zhangyi: 68db0cf10678 does not merged, skip the task_stack.h for 4.4] Signed-off-by: zhangyi (F) Signed-off-by: Greg Kroah-Hartman

fs/proc: Stop reporting eip and esp in /proc/PID/stat

2019-12-21T09:35:05Z

commit 0a1eb2d474edfe75466be6b4677ad84e5e8ca3f5 upstream. Reporting these fields on a non-current task is dangerous. If the task is in any state other than normal kernel code, they may contain garbage or even kernel addresses on some architectures. (x86_64 used to do this. I bet lots of architectures still do.) With CONFIG_THREAD_INFO_IN_TASK=y, it can OOPS, too. As far as I know, there are no use programs that make any material use of these fields, so just get rid of them. Reported-by: Jann Horn Signed-off-by: Andy Lutomirski Acked-by: Thomas Gleixner Cc: Al Viro Cc: Andrew Morton Cc: Borislav Petkov Cc: Brian Gerst Cc: Kees Cook Cc: Linus Torvalds Cc: Linux API Cc: Peter Zijlstra Cc: Tetsuo Handa Cc: Tycho Andersen Link: http://lkml.kernel.org/r/a5fed4c3f4e33ed25d4bb03567e329bc5a712bcc.1475257877.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: zhangyi (F) Signed-off-by: Greg Kroah-Hartman

proc/vmcore: Fix i386 build error of missing copy_oldmem_page_encrypted()

2019-11-25T14:54:47Z

[ Upstream commit cf089611f4c446285046fcd426d90c18f37d2905 ] Lianbo reported a build error with a particular 32-bit config, see Link below for details. Provide a weak copy_oldmem_page_encrypted() function which architectures can override, in the same manner other functionality in that file is supplied. Reported-by: Lianbo Jiang Signed-off-by: Borislav Petkov CC: x86@kernel.org Link: http://lkml.kernel.org/r/710b9d95-2f70-eadf-c4a1-c3dc80ee4ebb@redhat.com Signed-off-by: Sasha Levin

coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping

2019-06-22T06:18:27Z

commit 04f5866e41fb70690e28397487d8bd8eea7d712a upstream. The core dumping code has always run without holding the mmap_sem for writing, despite that is the only way to ensure that the entire vma layout will not change from under it. Only using some signal serialization on the processes belonging to the mm is not nearly enough. This was pointed out earlier. For example in Hugh's post from Jul 2017: https://lkml.kernel.org/r/alpine.LSU.2.11.1707191716030.2055@eggly.anvils "Not strictly relevant here, but a related note: I was very surprised to discover, only quite recently, how handle_mm_fault() may be called without down_read(mmap_sem) - when core dumping. That seems a misguided optimization to me, which would also be nice to correct" In particular because the growsdown and growsup can move the vm_start/vm_end the various loops the core dump does around the vma will not be consistent if page faults can happen concurrently. Pretty much all users calling mmget_not_zero()/get_task_mm() and then taking the mmap_sem had the potential to introduce unexpected side effects in the core dumping code. Adding mmap_sem for writing around the ->core_dump invocation is a viable long term fix, but it requires removing all copy user and page faults and to replace them with get_dump_page() for all binary formats which is not suitable as a short term fix. For the time being this solution manually covers the places that can confuse the core dump either by altering the vma layout or the vma flags while it runs. Once ->core_dump runs under mmap_sem for writing the function mmget_still_valid() can be dropped. Allowing mmap_sem protected sections to run in parallel with the coredump provides some minor parallelism advantage to the swapoff code (which seems to be safe enough by never mangling any vma field and can keep doing swapins in parallel to the core dumping) and to some other corner case. In order to facilitate the backporting I added "Fixes: 86039bd3b4e6" however the side effect of this same race condition in /proc/pid/mem should be reproducible since before 2.6.12-rc2 so I couldn't add any other "Fixes:" because there's no hash beyond the git genesis commit. Because find_extend_vma() is the only location outside of the process context that could modify the "mm" structures under mmap_sem for reading, by adding the mmget_still_valid() check to it, all other cases that take the mmap_sem for reading don't need the new check after mmget_not_zero()/get_task_mm(). The expand_stack() in page fault context also doesn't need the new check, because all tasks under core dumping are frozen. Link: http://lkml.kernel.org/r/20190325224949.11068-1-aarcange@redhat.com Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization") Signed-off-by: Andrea Arcangeli Reported-by: Jann Horn Suggested-by: Oleg Nesterov Acked-by: Peter Xu Reviewed-by: Mike Rapoport Reviewed-by: Oleg Nesterov Reviewed-by: Jann Horn Acked-by: Jason Gunthorpe Acked-by: Michal Hocko Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Joel Fernandes (Google) [mhocko@suse.com: stable 4.4 backport - drop infiniband part because of missing 5f9794dc94f59 - drop userfaultfd_event_wait_completion hunk because of missing 9cd75c3cd4c3d] - handle binder_update_page_range because of missing 720c241924046 - handle mlx5_ib_disassociate_ucontext - akaher@vmware.com ] Signed-off-by: Michal Hocko Signed-off-by: Greg Kroah-Hartman