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* Merge branch 'work.namei' of ↵Linus Torvalds2021-07-031-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs name lookup updates from Al Viro: "Small namei.c patch series, mostly to simplify the rules for nameidata state. It's actually from the previous cycle - but I didn't post it for review in time... Changes visible outside of fs/namei.c: file_open_root() calling conventions change, some freed bits in LOOKUP_... space" * 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: namei: make sure nd->depth is always valid teach set_nameidata() to handle setting the root as well take LOOKUP_{ROOT,ROOT_GRABBED,JUMPED} out of LOOKUP_... space switch file_open_root() to struct path
| * switch file_open_root() to struct pathAl Viro2021-04-071-2/+2
| | | | | | | | | | | | ... and provide file_open_root_mnt(), using the root of given mount. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | coredump: Limit what can interrupt coredumpsEric W. Biederman2021-06-101-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Olivier Langlois has been struggling with coredumps being incompletely written in processes using io_uring. Olivier Langlois <olivier@trillion01.com> writes: > io_uring is a big user of task_work and any event that io_uring made a > task waiting for that occurs during the core dump generation will > generate a TIF_NOTIFY_SIGNAL. > > Here are the detailed steps of the problem: > 1. io_uring calls vfs_poll() to install a task to a file wait queue > with io_async_wake() as the wakeup function cb from io_arm_poll_handler() > 2. wakeup function ends up calling task_work_add() with TWA_SIGNAL > 3. task_work_add() sets the TIF_NOTIFY_SIGNAL bit by calling > set_notify_signal() The coredump code deliberately supports being interrupted by SIGKILL, and depends upon prepare_signal to filter out all other signals. Now that signal_pending includes wake ups for TIF_NOTIFY_SIGNAL this hack in dump_emitted by the coredump code no longer works. Make the coredump code more robust by explicitly testing for all of the wakeup conditions the coredump code supports. This prevents new wakeup conditions from breaking the coredump code, as well as fixing the current issue. The filesystem code that the coredump code uses already limits itself to only aborting on fatal_signal_pending. So it should not develop surprising wake-up reasons either. v2: Don't remove the now unnecessary code in prepare_signal. Cc: stable@vger.kernel.org Fixes: 12db8b690010 ("entry: Add support for TIF_NOTIFY_SIGNAL") Reported-by: Olivier Langlois <olivier@trillion01.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | coredump: don't bother with do_truncate()Al Viro2021-03-081-29/+43
|/ | | | | | | | | | have dump_skip() just remember how much needs to be skipped, leave actual seeks/writing zeroes to the next dump_emit() or the end of coredump output, whichever comes first. And instead of playing with do_truncate() in the end, just write one NUL at the end of the last gap (if any). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/coredump: use kmap_local_page()Ira Weiny2021-02-261-2/+2
| | | | | | | | | | | In dump_user_range() there is no reason for the mapping to be global. Use kmap_local_page() rather than kmap. Link: https://lkml.kernel.org/r/20210203223328.558945-1-ira.weiny@intel.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* open: handle idmapped mounts in do_truncate()Christian Brauner2021-01-241-3/+7
| | | | | | | | | | | | | | | | | When truncating files the vfs will verify that the caller is privileged over the inode. Extend it to handle idmapped mounts. If the inode is accessed through an idmapped mount it is mapped according to the mount's user namespace. Afterwards the permissions 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. Link: https://lore.kernel.org/r/20210121131959.646623-16-christian.brauner@ubuntu.com 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 Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
* Merge branch 'exec-for-v5.11' of ↵Linus Torvalds2020-12-151-4/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull execve updates from Eric Biederman: "This set of changes ultimately fixes the interaction of posix file lock and exec. Fundamentally most of the change is just moving where unshare_files is called during exec, and tweaking the users of files_struct so that the count of files_struct is not unnecessarily played with. Along the way fcheck and related helpers were renamed to more accurately reflect what they do. There were also many other small changes that fell out, as this is the first time in a long time much of this code has been touched. Benchmarks haven't turned up any practical issues but Al Viro has observed a possibility for a lot of pounding on task_lock. So I have some changes in progress to convert put_files_struct to always rcu free files_struct. That wasn't ready for the merge window so that will have to wait until next time" * 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits) exec: Move io_uring_task_cancel after the point of no return coredump: Document coredump code exclusively used by cell spufs file: Remove get_files_struct file: Rename __close_fd_get_file close_fd_get_file file: Replace ksys_close with close_fd file: Rename __close_fd to close_fd and remove the files parameter file: Merge __alloc_fd into alloc_fd file: In f_dupfd read RLIMIT_NOFILE once. file: Merge __fd_install into fd_install proc/fd: In fdinfo seq_show don't use get_files_struct bpf/task_iter: In task_file_seq_get_next use task_lookup_next_fd_rcu proc/fd: In proc_readfd_common use task_lookup_next_fd_rcu file: Implement task_lookup_next_fd_rcu kcmp: In get_file_raw_ptr use task_lookup_fd_rcu proc/fd: In tid_fd_mode use task_lookup_fd_rcu file: Implement task_lookup_fd_rcu file: Rename fcheck lookup_fd_rcu file: Replace fcheck_files with files_lookup_fd_rcu file: Factor files_lookup_fd_locked out of fcheck_files file: Rename __fcheck_files to files_lookup_fd_raw ...
| * coredump: Document coredump code exclusively used by cell spufsEric W. Biederman2020-12-101-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Oleg Nesterov recently asked[1] why is there an unshare_files in do_coredump. After digging through all of the callers of lookup_fd it turns out that it is arch/powerpc/platforms/cell/spufs/coredump.c:coredump_next_context that needs the unshare_files in do_coredump. Looking at the history[2] this code was also the only piece of coredump code that required the unshare_files when the unshare_files was added. Looking at that code it turns out that cell is also the only architecture that implements elf_coredump_extra_notes_size and elf_coredump_extra_notes_write. I looked at the gdb repo[3] support for cell has been removed[4] in binutils 2.34. Geoff Levand reports he is still getting questions on how to run modern kernels on the PS3, from people using 3rd party firmware so this code is not dead. According to Wikipedia the last PS3 shipped in Japan sometime in 2017. So it will probably be a little while before everyone's hardware dies. Add some comments briefly documenting the coredump code that exists only to support cell spufs to make it easier to understand the coredump code. Eventually the hardware will be dead, or their won't be userspace tools, or the coredump code will be refactored and it will be too difficult to update a dead architecture and these comments make it easy to tell where to pull to remove cell spufs support. [1] https://lkml.kernel.org/r/20201123175052.GA20279@redhat.com [2] 179e037fc137 ("do_coredump(): make sure that descriptor table isn't shared") [3] git://sourceware.org/git/binutils-gdb.git [4] abf516c6931a ("Remove Cell Broadband Engine debugging support"). Link: https://lkml.kernel.org/r/87h7pdnlzv.fsf_-_@x220.int.ebiederm.org Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
| * exec: Simplify unshare_filesEric W. Biederman2020-12-101-4/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Now that exec no longer needs to return the unshared files to their previous value there is no reason to return displaced. Instead when unshare_fd creates a copy of the file table, call put_files_struct before returning from unshare_files. Acked-by: Christian Brauner <christian.brauner@ubuntu.com> v1: https://lkml.kernel.org/r/20200817220425.9389-2-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20201120231441.29911-2-ebiederm@xmission.com Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* | coredump: fix core_pattern parse errorMenglong Dong2020-12-061-1/+2
|/ | | | | | | | | | | | | | | | | | | | | | | 'format_corename()' will splite 'core_pattern' on spaces when it is in pipe mode, and take helper_argv[0] as the path to usermode executable. It works fine in most cases. However, if there is a space between '|' and '/file/path', such as '| /usr/lib/systemd/systemd-coredump %P %u %g', then helper_argv[0] will be parsed as '', and users will get a 'Core dump to | disabled'. It is not friendly to users, as the pattern above was valid previously. Fix this by ignoring the spaces between '|' and '/file/path'. Fixes: 315c69261dd3 ("coredump: split pipe command whitespace before expanding template") Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Paul Wise <pabs3@bonedaddy.net> Cc: Jakub Wilk <jwilk@jwilk.net> [https://bugs.debian.org/924398] Cc: Neil Horman <nhorman@tuxdriver.com> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/5fb62870.1c69fb81.8ef5d.af76@mx.google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshotJann Horn2020-10-161-1/+80
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In both binfmt_elf and binfmt_elf_fdpic, use a new helper dump_vma_snapshot() to take a snapshot of the VMA list (including the gate VMA, if we have one) while protected by the mmap_lock, and then use that snapshot instead of walking the VMA list without locking. An alternative approach would be to keep the mmap_lock held across the entire core dumping operation; however, keeping the mmap_lock locked while we may be blocked for an unbounded amount of time (e.g. because we're dumping to a FUSE filesystem or so) isn't really optimal; the mmap_lock blocks things like the ->release handler of userfaultfd, and we don't really want critical system daemons to grind to a halt just because someone "gifted" them SCM_RIGHTS to an eternally-locked userfaultfd, or something like that. Since both the normal ELF code and the FDPIC ELF code need this functionality (and if any other binfmt wants to add coredump support in the future, they'd probably need it, too), implement this with a common helper in fs/coredump.c. A downside of this approach is that we now need a bigger amount of kernel memory per userspace VMA in the normal ELF case, and that we need O(n) kernel memory in the FDPIC ELF case at all; but 40 bytes per VMA shouldn't be terribly bad. There currently is a data race between stack expansion and anything that reads ->vm_start or ->vm_end under the mmap_lock held in read mode; to mitigate that for core dumping, take the mmap_lock in write mode when taking a snapshot of the VMA hierarchy. (If we only took the mmap_lock in read mode, we could end up with a corrupted core dump if someone does get_user_pages_remote() concurrently. Not really a major problem, but taking the mmap_lock either way works here, so we might as well avoid the issue.) (This doesn't do anything about the existing data races with stack expansion in other mm code.) Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Hugh Dickins <hughd@google.com> Link: http://lkml.kernel.org/r/20200827114932.3572699-6-jannh@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: rework elf/elf_fdpic vma_dump_size() into common helperJann Horn2020-10-161-0/+101
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | At the moment, the binfmt_elf and binfmt_elf_fdpic code have slightly different code to figure out which VMAs should be dumped, and if so, whether the dump should contain the entire VMA or just its first page. Eliminate duplicate code by reworking the binfmt_elf version into a generic core dumping helper in coredump.c. As part of that, change the heuristic for detecting executable/library header pages to check whether the inode is executable instead of looking at the file mode. This is less problematic in terms of locking because it lets us avoid get_user() under the mmap_sem. (And arguably it looks nicer and makes more sense in generic code.) Adjust a little bit based on the binfmt_elf_fdpic version: ->anon_vma is only meaningful under CONFIG_MMU, otherwise we have to assume that the VMA has been written to. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Hugh Dickins <hughd@google.com> Link: http://lkml.kernel.org/r/20200827114932.3572699-5-jannh@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: refactor page range dumping into common helperJann Horn2020-10-161-0/+34
| | | | | | | | | | | | | | | | Both fs/binfmt_elf.c and fs/binfmt_elf_fdpic.c need to dump ranges of pages into the coredump file. Extract that logic into a common helper. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Hugh Dickins <hughd@google.com> Link: http://lkml.kernel.org/r/20200827114932.3572699-4-jannh@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: let dump_emit() bail out on short writesJann Horn2020-10-161-11/+11
| | | | | | | | | | | | | | | | | | | | dump_emit() has a retry loop, but there seems to be no way for that retry logic to actually be used; and it was also buggy, writing the same data repeatedly after a short write. Let's just bail out on a short write. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Hugh Dickins <hughd@google.com> Link: http://lkml.kernel.org/r/20200827114932.3572699-3-jannh@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: add %f for executable filenameLepton Wu2020-08-121-4/+13
| | | | | | | | | | | | | | | | | | | | | The document reads "%e" should be "executable filename" while actually it could be changed by things like pr_ctl PR_SET_NAME. People who uses "%e" in core_pattern get surprised when they find out they get thread name instead of executable filename. This is either a bug of document or a bug of code. Since the behavior of "%e" is there for long time, it could bring another surprise for users if we "fix" the code. So we just "fix" the document. And more, for users who really need the "executable filename" in core_pattern, we introduce a new "%f" for the real executable filename. We already have "%E" for executable path in kernel, so just reuse most of its code for the new added "%f" format. Signed-off-by: Lepton Wu <ytht.net@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200701031432.2978761-1-ytht.net@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mmap locking API: convert mmap_sem commentsMichel Lespinasse2020-06-091-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | Convert comments that reference mmap_sem to reference mmap_lock instead. [akpm@linux-foundation.org: fix up linux-next leftovers] [akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil] [akpm@linux-foundation.org: more linux-next fixups, per Michel] Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mmap locking API: use coccinelle to convert mmap_sem rwsem call sitesMichel Lespinasse2020-06-091-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change converts the existing mmap_sem rwsem calls to use the new mmap locking API instead. The change is generated using coccinelle with the following rule: // spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir . @@ expression mm; @@ ( -init_rwsem +mmap_init_lock | -down_write +mmap_write_lock | -down_write_killable +mmap_write_lock_killable | -down_write_trylock +mmap_write_trylock | -up_write +mmap_write_unlock | -downgrade_write +mmap_write_downgrade | -down_read +mmap_read_lock | -down_read_killable +mmap_read_lock_killable | -down_read_trylock +mmap_read_trylock | -up_read +mmap_read_unlock ) -(&mm->mmap_sem) +(mm) Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: fix crash when umh is disabledLuis Chamberlain2020-04-281-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 64e90a8acb859 ("Introduce STATIC_USERMODEHELPER to mediate call_usermodehelper()") added the optiont to disable all call_usermodehelper() calls by setting STATIC_USERMODEHELPER_PATH to an empty string. When this is done, and crashdump is triggered, it will crash on null pointer dereference, since we make assumptions over what call_usermodehelper_exec() did. This has been reported by Sergey when one triggers a a coredump with the following configuration: ``` CONFIG_STATIC_USERMODEHELPER=y CONFIG_STATIC_USERMODEHELPER_PATH="" kernel.core_pattern = |/usr/lib/systemd/systemd-coredump %P %u %g %s %t %c %h %e ``` The way disabling the umh was designed was that call_usermodehelper_exec() would just return early, without an error. But coredump assumes certain variables are set up for us when this happens, and calls ile_start_write(cprm.file) with a NULL file. [ 2.819676] BUG: kernel NULL pointer dereference, address: 0000000000000020 [ 2.819859] #PF: supervisor read access in kernel mode [ 2.820035] #PF: error_code(0x0000) - not-present page [ 2.820188] PGD 0 P4D 0 [ 2.820305] Oops: 0000 [#1] SMP PTI [ 2.820436] CPU: 2 PID: 89 Comm: a Not tainted 5.7.0-rc1+ #7 [ 2.820680] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190711_202441-buildvm-armv7-10.arm.fedoraproject.org-2.fc31 04/01/2014 [ 2.821150] RIP: 0010:do_coredump+0xd80/0x1060 [ 2.821385] Code: e8 95 11 ed ff 48 c7 c6 cc a7 b4 81 48 8d bd 28 ff ff ff 89 c2 e8 70 f1 ff ff 41 89 c2 85 c0 0f 84 72 f7 ff ff e9 b4 fe ff ff <48> 8b 57 20 0f b7 02 66 25 00 f0 66 3d 00 8 0 0f 84 9c 01 00 00 44 [ 2.822014] RSP: 0000:ffffc9000029bcb8 EFLAGS: 00010246 [ 2.822339] RAX: 0000000000000000 RBX: ffff88803f860000 RCX: 000000000000000a [ 2.822746] RDX: 0000000000000009 RSI: 0000000000000282 RDI: 0000000000000000 [ 2.823141] RBP: ffffc9000029bde8 R08: 0000000000000000 R09: ffffc9000029bc00 [ 2.823508] R10: 0000000000000001 R11: ffff88803dec90be R12: ffffffff81c39da0 [ 2.823902] R13: ffff88803de84400 R14: 0000000000000000 R15: 0000000000000000 [ 2.824285] FS: 00007fee08183540(0000) GS:ffff88803e480000(0000) knlGS:0000000000000000 [ 2.824767] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 2.825111] CR2: 0000000000000020 CR3: 000000003f856005 CR4: 0000000000060ea0 [ 2.825479] Call Trace: [ 2.825790] get_signal+0x11e/0x720 [ 2.826087] do_signal+0x1d/0x670 [ 2.826361] ? force_sig_info_to_task+0xc1/0xf0 [ 2.826691] ? force_sig_fault+0x3c/0x40 [ 2.826996] ? do_trap+0xc9/0x100 [ 2.827179] exit_to_usermode_loop+0x49/0x90 [ 2.827359] prepare_exit_to_usermode+0x77/0xb0 [ 2.827559] ? invalid_op+0xa/0x30 [ 2.827747] ret_from_intr+0x20/0x20 [ 2.827921] RIP: 0033:0x55e2c76d2129 [ 2.828107] Code: 2d ff ff ff e8 68 ff ff ff 5d c6 05 18 2f 00 00 01 c3 0f 1f 80 00 00 00 00 c3 0f 1f 80 00 00 00 00 e9 7b ff ff ff 55 48 89 e5 <0f> 0b b8 00 00 00 00 5d c3 66 2e 0f 1f 84 0 0 00 00 00 00 0f 1f 40 [ 2.828603] RSP: 002b:00007fffeba5e080 EFLAGS: 00010246 [ 2.828801] RAX: 000055e2c76d2125 RBX: 0000000000000000 RCX: 00007fee0817c718 [ 2.829034] RDX: 00007fffeba5e188 RSI: 00007fffeba5e178 RDI: 0000000000000001 [ 2.829257] RBP: 00007fffeba5e080 R08: 0000000000000000 R09: 00007fee08193c00 [ 2.829482] R10: 0000000000000009 R11: 0000000000000000 R12: 000055e2c76d2040 [ 2.829727] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 2.829964] CR2: 0000000000000020 [ 2.830149] ---[ end trace ceed83d8c68a1bf1 ]--- ``` Cc: <stable@vger.kernel.org> # v4.11+ Fixes: 64e90a8acb85 ("Introduce STATIC_USERMODEHELPER to mediate call_usermodehelper()") BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=199795 Reported-by: Tony Vroon <chainsaw@gentoo.org> Reported-by: Sergey Kvachonok <ravenexp@gmail.com> Tested-by: Sergei Trofimovich <slyfox@gentoo.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Link: https://lore.kernel.org/r/20200416162859.26518-1-mcgrof@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* coredump: fix null pointer dereference on coredumpSudip Mukherjee2020-04-211-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | If the core_pattern is set to "|" and any process segfaults then we get a null pointer derefernce while trying to coredump. The call stack shows: RIP: do_coredump+0x628/0x11c0 When the core_pattern has only "|" there is no use of trying the coredump and we can check that while formating the corename and exit with an error. After this change I get: format_corename failed Aborting core Fixes: 315c69261dd3 ("coredump: split pipe command whitespace before expanding template") Reported-by: Matthew Ruffell <matthew.ruffell@canonical.com> Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Paul Wise <pabs3@bonedaddy.net> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/20200416194612.21418-1-sudipm.mukherjee@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pipe: use exclusive waits when reading or writingLinus Torvalds2020-02-081-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This makes the pipe code use separate wait-queues and exclusive waiting for readers and writers, avoiding a nasty thundering herd problem when there are lots of readers waiting for data on a pipe (or, less commonly, lots of writers waiting for a pipe to have space). While this isn't a common occurrence in the traditional "use a pipe as a data transport" case, where you typically only have a single reader and a single writer process, there is one common special case: using a pipe as a source of "locking tokens" rather than for data communication. In particular, the GNU make jobserver code ends up using a pipe as a way to limit parallelism, where each job consumes a token by reading a byte from the jobserver pipe, and releases the token by writing a byte back to the pipe. This pattern is fairly traditional on Unix, and works very well, but will waste a lot of time waking up a lot of processes when only a single reader needs to be woken up when a writer releases a new token. A simplified test-case of just this pipe interaction is to create 64 processes, and then pass a single token around between them (this test-case also intentionally passes another token that gets ignored to test the "wake up next" logic too, in case anybody wonders about it): #include <unistd.h> int main(int argc, char **argv) { int fd[2], counters[2]; pipe(fd); counters[0] = 0; counters[1] = -1; write(fd[1], counters, sizeof(counters)); /* 64 processes */ fork(); fork(); fork(); fork(); fork(); fork(); do { int i; read(fd[0], &i, sizeof(i)); if (i < 0) continue; counters[0] = i+1; write(fd[1], counters, (1+(i & 1)) *sizeof(int)); } while (counters[0] < 1000000); return 0; } and in a perfect world, passing that token around should only cause one context switch per transfer, when the writer of a token causes a directed wakeup of just a single reader. But with the "writer wakes all readers" model we traditionally had, on my test box the above case causes more than an order of magnitude more scheduling: instead of the expected ~1M context switches, "perf stat" shows 231,852.37 msec task-clock # 15.857 CPUs utilized 11,250,961 context-switches # 0.049 M/sec 616,304 cpu-migrations # 0.003 M/sec 1,648 page-faults # 0.007 K/sec 1,097,903,998,514 cycles # 4.735 GHz 120,781,778,352 instructions # 0.11 insn per cycle 27,997,056,043 branches # 120.754 M/sec 283,581,233 branch-misses # 1.01% of all branches 14.621273891 seconds time elapsed 0.018243000 seconds user 3.611468000 seconds sys before this commit. After this commit, I get 5,229.55 msec task-clock # 3.072 CPUs utilized 1,212,233 context-switches # 0.232 M/sec 103,951 cpu-migrations # 0.020 M/sec 1,328 page-faults # 0.254 K/sec 21,307,456,166 cycles # 4.074 GHz 12,947,819,999 instructions # 0.61 insn per cycle 2,881,985,678 branches # 551.096 M/sec 64,267,015 branch-misses # 2.23% of all branches 1.702148350 seconds time elapsed 0.004868000 seconds user 0.110786000 seconds sys instead. Much better. [ Note! This kernel improvement seems to be very good at triggering a race condition in the make jobserver (in GNU make 4.2.1) for me. It's a long known bug that was fixed back in June 2017 by GNU make commit b552b0525198 ("[SV 51159] Use a non-blocking read with pselect to avoid hangs."). But there wasn't a new release of GNU make until 4.3 on Jan 19 2020, so a number of distributions may still have the buggy version. Some have backported the fix to their 4.2.1 release, though, and even without the fix it's quite timing-dependent whether the bug actually is hit. ] Josh Triplett says: "I've been hammering on your pipe fix patch (switching to exclusive wait queues) for a month or so, on several different systems, and I've run into no issues with it. The patch *substantially* improves parallel build times on large (~100 CPU) systems, both with parallel make and with other things that use make's pipe-based jobserver. All current distributions (including stable and long-term stable distributions) have versions of GNU make that no longer have the jobserver bug" Tested-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: split pipe command whitespace before expanding templatePaul Wise2019-08-031-5/+39
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Save the offsets of the start of each argument to avoid having to update pointers to each argument after every corename krealloc and to avoid having to duplicate the memory for the dump command. Executable names containing spaces were previously being expanded from %e or %E and then split in the middle of the filename. This is incorrect behaviour since an argument list can represent arguments with spaces. The splitting could lead to extra arguments being passed to the core dump handler that it might have interpreted as options or ignored completely. Core dump handlers that are not aware of this Linux kernel issue will be using %e or %E without considering that it may be split and so they will be vulnerable to processes with spaces in their names breaking their argument list. If their internals are otherwise well written, such as if they are written in shell but quote arguments, they will work better after this change than before. If they are not well written, then there is a slight chance of breakage depending on the details of the code but they will already be fairly broken by the split filenames. Core dump handlers that are aware of this Linux kernel issue will be placing %e or %E as the last item in their core_pattern and then aggregating all of the remaining arguments into one, separated by spaces. Alternatively they will be obtaining the filename via other methods. Both of these will be compatible with the new arrangement. A side effect from this change is that unknown template types (for example %z) result in an empty argument to the dump handler instead of the argument being dropped. This is a desired change as: It is easier for dump handlers to process empty arguments than dropped ones, especially if they are written in shell or don't pass each template item with a preceding command-line option in order to differentiate between individual template types. Most core_patterns in the wild do not use options so they can confuse different template types (especially numeric ones) if an earlier one gets dropped in old kernels. If the kernel introduces a new template type and a core_pattern uses it, the core dump handler might not expect that the argument can be dropped in old kernels. For example, this can result in security issues when %d is dropped in old kernels. This happened with the corekeeper package in Debian and resulted in the interface between corekeeper and Linux having to be rewritten to use command-line options to differentiate between template types. The core_pattern for most core dump handlers is written by the handler author who would generally not insert unknown template types so this change should be compatible with all the core dump handlers that exist. Link: http://lkml.kernel.org/r/20190528051142.24939-1-pabs3@bonedaddy.net Fixes: 74aadce98605 ("core_pattern: allow passing of arguments to user mode helper when core_pattern is a pipe") Signed-off-by: Paul Wise <pabs3@bonedaddy.net> Reported-by: Jakub Wilk <jwilk@jwilk.net> [https://bugs.debian.org/924398] Reported-by: Paul Wise <pabs3@bonedaddy.net> [https://lore.kernel.org/linux-fsdevel/c8b7ecb8508895bf4adb62a748e2ea2c71854597.camel@bonedaddy.net/] Suggested-by: Jakub Wilk <jwilk@jwilk.net> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* signal: Distinguish between kernel_siginfo and siginfoEric W. Biederman2018-10-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Linus recently observed that if we did not worry about the padding member in struct siginfo it is only about 48 bytes, and 48 bytes is much nicer than 128 bytes for allocating on the stack and copying around in the kernel. The obvious thing of only adding the padding when userspace is including siginfo.h won't work as there are sigframe definitions in the kernel that embed struct siginfo. So split siginfo in two; kernel_siginfo and siginfo. Keeping the traditional name for the userspace definition. While the version that is used internally to the kernel and ultimately will not be padded to 128 bytes is called kernel_siginfo. The definition of struct kernel_siginfo I have put in include/signal_types.h A set of buildtime checks has been added to verify the two structures have the same field offsets. To make it easy to verify the change kernel_siginfo retains the same size as siginfo. The reduction in size comes in a following change. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* Merge branch 'misc.compat' of ↵Linus Torvalds2017-11-171-6/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull compat and uaccess updates from Al Viro: - {get,put}_compat_sigset() series - assorted compat ioctl stuff - more set_fs() elimination - a few more timespec64 conversions - several removals of pointless access_ok() in places where it was followed only by non-__ variants of primitives * 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (24 commits) coredump: call do_unlinkat directly instead of sys_unlink fs: expose do_unlinkat for built-in callers ext4: take handling of EXT4_IOC_GROUP_ADD into a helper, get rid of set_fs() ipmi: get rid of pointless access_ok() pi433: sanitize ioctl cxlflash: get rid of pointless access_ok() mtdchar: get rid of pointless access_ok() r128: switch compat ioctls to drm_ioctl_kernel() selection: get rid of field-by-field copyin VT_RESIZEX: get rid of field-by-field copyin i2c compat ioctls: move to ->compat_ioctl() sched_rr_get_interval(): move compat to native, get rid of set_fs() mips: switch to {get,put}_compat_sigset() sparc: switch to {get,put}_compat_sigset() s390: switch to {get,put}_compat_sigset() ppc: switch to {get,put}_compat_sigset() parisc: switch to {get,put}_compat_sigset() get_compat_sigset() get rid of {get,put}_compat_itimerspec() io_getevents: Use timespec64 to represent timeouts ...
| * coredump: call do_unlinkat directly instead of sys_unlinkChristoph Hellwig2017-11-101-6/+1
| | | | | | | | | | | | | | And stop messing with the address limit. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman2017-11-021-0/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* mm: treewide: remove GFP_TEMPORARY allocation flagMichal Hocko2017-09-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | GFP_TEMPORARY was introduced by commit e12ba74d8ff3 ("Group short-lived and reclaimable kernel allocations") along with __GFP_RECLAIMABLE. It's primary motivation was to allow users to tell that an allocation is short lived and so the allocator can try to place such allocations close together and prevent long term fragmentation. As much as this sounds like a reasonable semantic it becomes much less clear when to use the highlevel GFP_TEMPORARY allocation flag. How long is temporary? Can the context holding that memory sleep? Can it take locks? It seems there is no good answer for those questions. The current implementation of GFP_TEMPORARY is basically GFP_KERNEL | __GFP_RECLAIMABLE which in itself is tricky because basically none of the existing caller provide a way to reclaim the allocated memory. So this is rather misleading and hard to evaluate for any benefits. I have checked some random users and none of them has added the flag with a specific justification. I suspect most of them just copied from other existing users and others just thought it might be a good idea to use without any measuring. This suggests that GFP_TEMPORARY just motivates for cargo cult usage without any reasoning. I believe that our gfp flags are quite complex already and especially those with highlevel semantic should be clearly defined to prevent from confusion and abuse. Therefore I propose dropping GFP_TEMPORARY and replace all existing users to simply use GFP_KERNEL. Please note that SLAB users with shrinkers will still get __GFP_RECLAIMABLE heuristic and so they will be placed properly for memory fragmentation prevention. I can see reasons we might want some gfp flag to reflect shorterm allocations but I propose starting from a clear semantic definition and only then add users with proper justification. This was been brought up before LSF this year by Matthew [1] and it turned out that GFP_TEMPORARY really doesn't have a clear semantic. It seems to be a heuristic without any measured advantage for most (if not all) its current users. The follow up discussion has revealed that opinions on what might be temporary allocation differ a lot between developers. So rather than trying to tweak existing users into a semantic which they haven't expected I propose to simply remove the flag and start from scratch if we really need a semantic for short term allocations. [1] http://lkml.kernel.org/r/20170118054945.GD18349@bombadil.infradead.org [akpm@linux-foundation.org: fix typo] [akpm@linux-foundation.org: coding-style fixes] [sfr@canb.auug.org.au: drm/i915: fix up] Link: http://lkml.kernel.org/r/20170816144703.378d4f4d@canb.auug.org.au Link: http://lkml.kernel.org/r/20170728091904.14627-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Neil Brown <neilb@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar2017-03-021-0/+1
| | | | | | | | | | | | | | | | | | | | <linux/sched/task_stack.h> We are going to split <linux/sched/task_stack.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/task_stack.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar2017-03-021-1/+1
| | | | | | | | | | | | | | | | | | | | <linux/sched/signal.h> We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/signal.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar2017-03-021-0/+1
| | | | | | | | | | | | | | | | | | | | <linux/sched/coredump.h> We are going to split <linux/sched/coredump.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/coredump.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* coredump: Ensure proper size of sparse core filesDave Kleikamp2017-01-141-0/+18
| | | | | | | | | | | | | | | | | | If the last section of a core file ends with an unmapped or zero page, the size of the file does not correspond with the last dump_skip() call. gdb complains that the file is truncated and can be confusing to users. After all of the vma sections are written, make sure that the file size is no smaller than the current file position. This problem can be demonstrated with gdb's bigcore testcase on the sparc architecture. Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Replace <asm/uaccess.h> with <linux/uaccess.h> globallyLinus Torvalds2016-12-241-1/+1
| | | | | | | | | | | | | This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>' sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: fix unfreezable coredumping taskAndrey Ryabinin2016-11-111-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | It could be not possible to freeze coredumping task when it waits for 'core_state->startup' completion, because threads are frozen in get_signal() before they got a chance to complete 'core_state->startup'. Inability to freeze a task during suspend will cause suspend to fail. Also CRIU uses cgroup freezer during dump operation. So with an unfreezable task the CRIU dump will fail because it waits for a transition from 'FREEZING' to 'FROZEN' state which will never happen. Use freezer_do_not_count() to tell freezer to ignore coredumping task while it waits for core_state->startup completion. Link: http://lkml.kernel.org/r/1475225434-3753-1-git-send-email-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Pavel Machek <pavel@ucw.cz> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Tejun Heo <tj@kernel.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: fix dumping through pipesMateusz Guzik2016-06-071-1/+3
| | | | | | | | | | | | | | | | | | The offset in the core file used to be tracked with ->written field of the coredump_params structure. The field was retired in favour of file->f_pos. However, ->f_pos is not maintained for pipes which leads to breakage. Restore explicit tracking of the offset in coredump_params. Introduce ->pos field for this purpose since ->written was already reused. Fixes: a00839395103 ("get rid of coredump_params->written"). Reported-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> Signed-off-by: Mateusz Guzik <mguzik@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* coredump: make coredump_wait wait for mmap_sem for write killableMichal Hocko2016-05-231-1/+3
| | | | | | | | | | | | | | | | | | | | coredump_wait waits for mmap_sem for write currently which can prevent oom_reaper to reclaim the oom victims address space asynchronously because that requires mmap_sem for read. This might happen if the oom victim is multi threaded and some thread(s) is holding mmap_sem for read (e.g. page fault) and it is stuck in the page allocator while other thread(s) reached coredump_wait already. This patch simply uses down_write_killable and bails out with EINTR if the lock got interrupted by the fatal signal. do_coredump will return right away and do_group_exit will take care to zap the whole thread group. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: only charge written data against RLIMIT_COREOmar Sandoval2016-05-121-3/+2
| | | | | | | | | | | | | Commit 9b56d54380ad ("dump_skip(): dump_seek() replacement taking coredump_params") introduced a regression with regard to RLIMIT_CORE. Previously, when a core dump was sparse, only the data that was actually written out would count against the limit. Now, the sparse ranges are also included, which leads to truncated core dumps when the actual disk usage is still well below the limit. Restore the old behavior by only counting what gets emitted and ignoring what gets skipped. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* coredump: get rid of coredump_params->writtenOmar Sandoval2016-05-121-5/+3
| | | | | | | cprm->written is redundant with cprm->file->f_pos, so use that instead. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/coredump: prevent fsuid=0 dumps into user-controlled directoriesJann Horn2016-03-221-4/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit fixes the following security hole affecting systems where all of the following conditions are fulfilled: - The fs.suid_dumpable sysctl is set to 2. - The kernel.core_pattern sysctl's value starts with "/". (Systems where kernel.core_pattern starts with "|/" are not affected.) - Unprivileged user namespace creation is permitted. (This is true on Linux >=3.8, but some distributions disallow it by default using a distro patch.) Under these conditions, if a program executes under secure exec rules, causing it to run with the SUID_DUMP_ROOT flag, then unshares its user namespace, changes its root directory and crashes, the coredump will be written using fsuid=0 and a path derived from kernel.core_pattern - but this path is interpreted relative to the root directory of the process, allowing the attacker to control where a coredump will be written with root privileges. To fix the security issue, always interpret core_pattern for dumps that are written under SUID_DUMP_ROOT relative to the root directory of init. Signed-off-by: Jann Horn <jann@thejh.net> Acked-by: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/coredump: prevent "" / "." / ".." core path componentsJann Horn2016-01-201-0/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Let %h and %e print empty values as "!", "." as "!" and ".." as "!.". This prevents hostnames and comm values that are empty or consist of one or two dots from changing the directory level at which the corefile will be stored. Consider the case where someone decides to sort coredumps by hostname with a core pattern like "/cores/%h/core.%e.%p.%t" or so. In this case, hostnames "" and "." would cause the coredump to land directly in /cores, which is not what the intent behind the core pattern is, and ".." would cause the coredump to land in /. Yeah, there probably aren't many people who do that, but I still don't want this edgecase to be kind of broken. It seems very unlikely that this caused security issues anywhere, so I'm not requesting a stable backport. [akpm@linux-foundation.org: tweak code comment] Signed-off-by: Jann Horn <jann@thejh.net> Acked-by: Kees Cook <keescook@chromium.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: Use 64bit time for unix time of coredumpArnd Bergmann2015-12-061-3/+5
| | | | | | | | | | | | struct timeval on 32-bit systems will have its tv_sec value overflow in year 2038 and beyond. Use a 64 bit value to print time of the coredump in seconds. ktime_get_real_seconds is chosen here for efficiency reasons. Suggested by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* coredump: change zap_threads() and zap_process() to use for_each_thread()Oleg Nesterov2015-11-061-14/+13
| | | | | | | | | | | | | | | | | Change zap_threads() paths to use for_each_thread() rather than while_each_thread(). While at it, change zap_threads() to avoid the nested if's to make the code more readable and lessen the indentation. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Kyle Walker <kwalker@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Stanislav Kozina <skozina@redhat.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: ensure all coredumping tasks have SIGNAL_GROUP_COREDUMPOleg Nesterov2015-11-061-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | task_will_free_mem() is wrong in many ways, and in particular the SIGNAL_GROUP_COREDUMP check is not reliable: a task can participate in the coredumping without SIGNAL_GROUP_COREDUMP bit set. change zap_threads() paths to always set SIGNAL_GROUP_COREDUMP even if other CLONE_VM processes can't react to SIGKILL. Fortunately, at least oom-kill case if fine; it kills all tasks sharing the same mm, so it should also kill the process which actually dumps the core. The change in prepare_signal() is not strictly necessary, it just ensures that the patch does not bring another subtle behavioural change. But it reminds us that this SIGNAL_GROUP_EXIT/COREDUMP case needs more changes. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Kyle Walker <kwalker@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Stanislav Kozina <skozina@redhat.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs: Don't dump core if the corefile would become world-readable.Jann Horn2015-09-101-2/+6
| | | | | | | | | | | | | | | | | | | On a filesystem like vfat, all files are created with the same owner and mode independent of who created the file. When a vfat filesystem is mounted with root as owner of all files and read access for everyone, root's processes left world-readable coredumps on it (but other users' processes only left empty corefiles when given write access because of the uid mismatch). Given that the old behavior was inconsistent and insecure, I don't see a problem with changing it. Now, all processes refuse to dump core unless the resulting corefile will only be readable by their owner. Signed-off-by: Jann Horn <jann@thejh.net> Acked-by: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs: if a coredump already exists, unlink and recreate with O_EXCLJann Horn2015-09-101-6/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It was possible for an attacking user to trick root (or another user) into writing his coredumps into an attacker-readable, pre-existing file using rename() or link(), causing the disclosure of secret data from the victim process' virtual memory. Depending on the configuration, it was also possible to trick root into overwriting system files with coredumps. Fix that issue by never writing coredumps into existing files. Requirements for the attack: - The attack only applies if the victim's process has a nonzero RLIMIT_CORE and is dumpable. - The attacker can trick the victim into coredumping into an attacker-writable directory D, either because the core_pattern is relative and the victim's cwd is attacker-writable or because an absolute core_pattern pointing to a world-writable directory is used. - The attacker has one of these: A: on a system with protected_hardlinks=0: execute access to a folder containing a victim-owned, attacker-readable file on the same partition as D, and the victim-owned file will be deleted before the main part of the attack takes place. (In practice, there are lots of files that fulfill this condition, e.g. entries in Debian's /var/lib/dpkg/info/.) This does not apply to most Linux systems because most distros set protected_hardlinks=1. B: on a system with protected_hardlinks=1: execute access to a folder containing a victim-owned, attacker-readable and attacker-writable file on the same partition as D, and the victim-owned file will be deleted before the main part of the attack takes place. (This seems to be uncommon.) C: on any system, independent of protected_hardlinks: write access to a non-sticky folder containing a victim-owned, attacker-readable file on the same partition as D (This seems to be uncommon.) The basic idea is that the attacker moves the victim-owned file to where he expects the victim process to dump its core. The victim process dumps its core into the existing file, and the attacker reads the coredump from it. If the attacker can't move the file because he does not have write access to the containing directory, he can instead link the file to a directory he controls, then wait for the original link to the file to be deleted (because the kernel checks that the link count of the corefile is 1). A less reliable variant that requires D to be non-sticky works with link() and does not require deletion of the original link: link() the file into D, but then unlink() it directly before the kernel performs the link count check. On systems with protected_hardlinks=0, this variant allows an attacker to not only gain information from coredumps, but also clobber existing, victim-writable files with coredumps. (This could theoretically lead to a privilege escalation.) Signed-off-by: Jann Horn <jann@thejh.net> Cc: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-linus' of ↵Linus Torvalds2015-07-041-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull more vfs updates from Al Viro: "Assorted VFS fixes and related cleanups (IMO the most interesting in that part are f_path-related things and Eric's descriptor-related stuff). UFS regression fixes (it got broken last cycle). 9P fixes. fs-cache series, DAX patches, Jan's file_remove_suid() work" [ I'd say this is much more than "fixes and related cleanups". The file_table locking rule change by Eric Dumazet is a rather big and fundamental update even if the patch isn't huge. - Linus ] * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (49 commits) 9p: cope with bogus responses from server in p9_client_{read,write} p9_client_write(): avoid double p9_free_req() 9p: forgetting to cancel request on interrupted zero-copy RPC dax: bdev_direct_access() may sleep block: Add support for DAX reads/writes to block devices dax: Use copy_from_iter_nocache dax: Add block size note to documentation fs/file.c: __fget() and dup2() atomicity rules fs/file.c: don't acquire files->file_lock in fd_install() fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation vfs: avoid creation of inode number 0 in get_next_ino namei: make set_root_rcu() return void make simple_positive() public ufs: use dir_pages instead of ufs_dir_pages() pagemap.h: move dir_pages() over there remove the pointless include of lglock.h fs: cleanup slight list_entry abuse xfs: Correctly lock inode when removing suid and file capabilities fs: Call security_ops->inode_killpriv on truncate fs: Provide function telling whether file_remove_privs() will do anything ...
| * vfs: add file_path() helperMiklos Szeredi2015-06-231-1/+1
| | | | | | | | | | | | | | | | | | | | Turn d_path(&file->f_path, ...); into file_path(file, ...); Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | coredump: add __printf attribute to cn_*printf functionsNicolas Iooss2015-06-251-4/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This allows detecting improper format string at build time, like: fs/coredump.c:225:5: warning: format '%ld' expects argument of type 'long int', but argument 3 has type 'int' [-Wformat=] err = cn_printf(cn, "%ld", cprm->siginfo->si_signo); ^ As si_signo is always an int, the format should be %d here. Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | coredump: use from_kuid/kgid when formatting corenameNicolas Iooss2015-06-251-2/+6
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | When adding __printf attribute to cn_printf, gcc reports some issues: fs/coredump.c:213:5: warning: format '%d' expects argument of type 'int', but argument 3 has type 'kuid_t' [-Wformat=] err = cn_printf(cn, "%d", cred->uid); ^ fs/coredump.c:217:5: warning: format '%d' expects argument of type 'int', but argument 3 has type 'kgid_t' [-Wformat=] err = cn_printf(cn, "%d", cred->gid); ^ These warnings come from the fact that the value of uid/gid needs to be extracted from the kuid_t/kgid_t structure before being used as an integer. More precisely, cred->uid and cred->gid need to be converted to either user-namespace uid/gid or to init_user_ns uid/gid. Use init_user_ns in order not to break existing ABI, and document this in Documentation/sysctl/kernel.txt. While at it, format uid and gid values with %u instead of %d because uid_t/__kernel_uid32_t and gid_t/__kernel_gid32_t are unsigned int. Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: accept any write methodAl Viro2015-04-111-1/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* coredump: Fix typo in commentBastien Nocera2015-02-201-1/+1
| | | | | Signed-off-by: Bastien Nocera <hadess@hadess.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* coredump: add %i/%I in core_pattern to report the tid of the crashed threadOleg Nesterov2014-10-141-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | format_corename() can only pass the leader's pid to the core handler, but there is no simple way to figure out which thread originated the coredump. As Jan explains, this also means that there is no simple way to create the backtrace of the crashed process: As programs are mostly compiled with implicit gcc -fomit-frame-pointer one needs program's .eh_frame section (equivalently PT_GNU_EH_FRAME segment) or .debug_frame section. .debug_frame usually is present only in separate debug info files usually not even installed on the system. While .eh_frame is a part of the executable/library (and it is even always mapped for C++ exceptions unwinding) it no longer has to be present anywhere on the disk as the program could be upgraded in the meantime and the running instance has its executable file already unlinked from disk. One possibility is to echo 0x3f >/proc/*/coredump_filter and dump all the file-backed memory including the executable's .eh_frame section. But that can create huge core files, for example even due to mmapped data files. Other possibility would be to read .eh_frame from /proc/PID/mem at the core_pattern handler time of the core dump. For the backtrace one needs to read the register state first which can be done from core_pattern handler: ptrace(PTRACE_SEIZE, tid, 0, PTRACE_O_TRACEEXIT) close(0); // close pipe fd to resume the sleeping dumper waitpid(); // should report EXIT PTRACE_GETREGS or other requests The remaining problem is how to get the 'tid' value of the crashed thread. It could be read from the first NT_PRSTATUS note of the core file but that makes the core_pattern handler complicated. Unfortunately %t is already used so this patch uses %i/%I. Automatic Bug Reporting Tool (https://github.com/abrt/abrt/wiki/overview) is experimenting with this. It is using the elfutils (https://fedorahosted.org/elfutils/) unwinder for generating the backtraces. Apart from not needing matching executables as mentioned above, another advantage is that we can get the backtrace without saving the core (which might be quite large) to disk. [mmilata@redhat.com: final paragraph of changelog] Signed-off-by: Jan Kratochvil <jan.kratochvil@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Jan Kratochvil <jan.kratochvil@redhat.com> Cc: Mark Wielaard <mjw@redhat.com> Cc: Martin Milata <mmilata@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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