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path: root/fs/coredump.c
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2017-09-13mm: treewide: remove GFP_TEMPORARY allocation flagMichal Hocko
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>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<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>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<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>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<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>
2017-01-14coredump: Ensure proper size of sparse core filesDave Kleikamp
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>
2016-12-24Replace <asm/uaccess.h> with <linux/uaccess.h> globallyLinus Torvalds
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>
2016-11-11coredump: fix unfreezable coredumping taskAndrey Ryabinin
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>
2016-06-07coredump: fix dumping through pipesMateusz Guzik
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>
2016-05-23coredump: make coredump_wait wait for mmap_sem for write killableMichal Hocko
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>
2016-05-12coredump: only charge written data against RLIMIT_COREOmar Sandoval
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>
2016-05-12coredump: get rid of coredump_params->writtenOmar Sandoval
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>
2016-03-22fs/coredump: prevent fsuid=0 dumps into user-controlled directoriesJann Horn
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>
2016-01-20fs/coredump: prevent "" / "." / ".." core path componentsJann Horn
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>
2015-12-06coredump: Use 64bit time for unix time of coredumpArnd Bergmann
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>
2015-11-06coredump: change zap_threads() and zap_process() to use for_each_thread()Oleg Nesterov
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>
2015-11-06coredump: ensure all coredumping tasks have SIGNAL_GROUP_COREDUMPOleg Nesterov
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>
2015-09-10fs: Don't dump core if the corefile would become world-readable.Jann Horn
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>
2015-09-10fs: if a coredump already exists, unlink and recreate with O_EXCLJann Horn
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>
2015-07-04Merge branch 'for-linus' of ↵Linus Torvalds
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 ...
2015-06-25coredump: add __printf attribute to cn_*printf functionsNicolas Iooss
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>
2015-06-25coredump: use from_kuid/kgid when formatting corenameNicolas Iooss
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>
2015-06-23vfs: add file_path() helperMiklos Szeredi
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>
2015-04-11coredump: accept any write methodAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-02-20coredump: Fix typo in commentBastien Nocera
Signed-off-by: Bastien Nocera <hadess@hadess.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-10-14coredump: add %i/%I in core_pattern to report the tid of the crashed threadOleg Nesterov
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>
2014-07-23coredump: fix the setting of PF_DUMPCORESilesh C V
Commit 079148b919d0 ("coredump: factor out the setting of PF_DUMPCORE") cleaned up the setting of PF_DUMPCORE by removing it from all the linux_binfmt->core_dump() and moving it to zap_threads().But this ended up clearing all the previously set flags. This causes issues during core generation when tsk->flags is checked again (eg. for PF_USED_MATH to dump floating point registers). Fix this. Signed-off-by: Silesh C V <svellattu@mvista.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Mandeep Singh Baines <msb@chromium.org> Cc: <stable@vger.kernel.org> [3.10+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-19coredump: fix va_list corruptionEric Dumazet
A va_list needs to be copied in case it needs to be used twice. Thanks to Hugh for debugging this issue, leading to various panics. Tested: lpq84:~# echo "|/foobar12345 %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h" >/proc/sys/kernel/core_pattern 'produce_core' is simply : main() { *(int *)0 = 1;} lpq84:~# ./produce_core Segmentation fault (core dumped) lpq84:~# dmesg | tail -1 [ 614.352947] Core dump to |/foobar12345 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 lpq84 (null) pipe failed Notice the last argument was replaced by a NULL (we were lucky enough to not crash, but do not try this on your production machine !) After fix : lpq83:~# echo "|/foobar12345 %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h %h" >/proc/sys/kernel/core_pattern lpq83:~# ./produce_core Segmentation fault lpq83:~# dmesg | tail -1 [ 740.800441] Core dump to |/foobar12345 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 lpq83 pipe failed Fixes: 5fe9d8ca21cc ("coredump: cn_vprintf() has no reason to call vsnprintf() twice") Signed-off-by: Eric Dumazet <edumazet@google.com> Diagnosed-by: Hugh Dickins <hughd@google.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: stable@vger.kernel.org # 3.11+ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-23coredump: make __get_dumpable/get_dumpable inline, kill fs/coredump.hOleg Nesterov
1. Remove fs/coredump.h. It is not clear why do we need it, it only declares __get_dumpable(), signal.c includes it for no reason. 2. Now that get_dumpable() and __get_dumpable() are really trivial make them inline in linux/sched.h. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> Cc: Alex Kelly <alex.page.kelly@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Petr Matousek <pmatouse@redhat.com> Cc: Vasily Kulikov <segoon@openwall.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-15dump_emit(): use __kernel_write(), not vfs_write()Al Viro
the caller has already done file_start_write()... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-15dump_align(): fix the dumb brainoAl Viro
Mea culpa - original variant used 64-by-32-bit division, which got caught very late. Getting rid of that wasn't hard, but I'd managed to botch the calling conventions in process ;-/ Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09constify do_coredump() argumentAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09new helper: dump_align()Al Viro
dump_skip to given alignment... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09dump_skip(): dump_seek() replacement taking coredump_paramsAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09make dump_emit() use vfs_write() instead of banging at ->f_op->write directlyAl Viro
... and deal with short writes properly - the output might be to pipe, after all; as it is, e.g. no-MMU case of elf_fdpic coredump can write a whole lot more than a page worth of data at one call. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09new helper: dump_emit()Al Viro
dump_write() analog, takes core_dump_params instead of file, keeps track of the amount written in cprm->written and checks for cprm->limit. Start using it in binfmt_elf.c... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-10-24file->f_op is never NULL...Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-09-11coredump: add new %P variable in core_patternStéphane Graber
Add a new %P variable to be used in core_pattern. This variable contains the global PID (PID in the init namespace) as %p contains the PID in the current namespace which isn't always what we want. The main use for this is to make it easier to handle crashes that happened within a container. With that new variables it's possible to have the crashes dumped into the container or forwarded to the host with the right PID (from the host's point of view). Signed-off-by: Stéphane Graber <stgraber@ubuntu.com> Reported-by: Hans Feldt <hans.feldt@ericsson.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Andy Whitcroft <apw@canonical.com> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-03coredump: '% at the end' shouldn't bypass core_uses_pid logicOleg Nesterov
"goto end" should not bypass the "Backward compatibility with core_uses_pid" code, move this label up. While at it, - It is ugly to copy '|' into cn->corename and then inc the pointer for argv_split(). Change format_corename() to increment pat_ptr instead. - Remove the dead "if (*pat_ptr == 0)" in format_corename(), we already checked it is not zero. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Colin Walters <walters@verbum.org> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Lennart Poettering <mzxreary@0pointer.de> Cc: Lucas De Marchi <lucas.de.marchi@gmail.com> 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>
2013-07-03coredump: kill call_count, add core_name_sizeOleg Nesterov
Imho, "atomic_t call_count" is ugly and should die. It buys nothing and in fact it can grow more than necessary, expand doesn't check if it was already incremented by another task. Kill it, and introduce "static int core_name_size" updated by expand_corename(). This is obviously racy too but harmless, and core_name_size never grows for no reason. We do not bother to to calculate the "right" new size, we simply do kmalloc(size_we_need) and use ksize() to rely on kmalloc_index's decision. Finally change format_corename() to use expand_corename(), krealloc(NULL) is fine. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Colin Walters <walters@verbum.org> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Lennart Poettering <mzxreary@0pointer.de> Cc: Lucas De Marchi <lucas.de.marchi@gmail.com> 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>
2013-07-03coredump: kill cn_escape(), introduce cn_esc_printf()Oleg Nesterov
The usage of cn_escape() looks really annoying, imho this sequence needs a wrapper. And it is buggy. If cn_printf() does expand_corename() cn_escape() writes to the freed memory. Introduce cn_esc_printf() which hopefully does this all right. It records the index before cn_vprintf(), not "char *" which is no longer valid (in general) after krealloc(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Colin Walters <walters@verbum.org> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Lennart Poettering <mzxreary@0pointer.de> Cc: Lucas De Marchi <lucas.de.marchi@gmail.com> 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>
2013-07-03coredump: cn_vprintf() has no reason to call vsnprintf() twiceOleg Nesterov
cn_vprintf() looks really overcomplicated and sub-optimal. We do not need vsnprintf(NULL) to calculate the size we need, we can simply try to print into the current buffer and expand/retry only if necessary. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Colin Walters <walters@verbum.org> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Lennart Poettering <mzxreary@0pointer.de> Cc: Lucas De Marchi <lucas.de.marchi@gmail.com> 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>
2013-07-03coredump: introduce cn_vprintf()Oleg Nesterov
Turn cn_printf(...) into cn_vprintf(va_list args), reintroduce cn_printf() as a trivial wrapper. This simplifies the next change and cn_vprintf() will have more callers. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Colin Walters <walters@verbum.org> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Lennart Poettering <mzxreary@0pointer.de> Cc: Lucas De Marchi <lucas.de.marchi@gmail.com> 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>
2013-07-03coredump: format_corename() can leak cn->corenameOleg Nesterov
do_coredump() assumes that format_corename() can only fail if expand_corename() fails and frees cn->corename. This is not true, for example cn_print_exe_file() can fail and in this case nobody frees cn->corename. Change do_coredump() to always do kfree(cn->corename) after it calls format_corename() (NULL is fine), change expand_corename() to do nothing if kmalloc() fails. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Colin Walters <walters@verbum.org> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Lennart Poettering <mzxreary@0pointer.de> Cc: Lucas De Marchi <lucas.de.marchi@gmail.com> 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>
2013-05-04do_coredump(): don't wait for thaw if coredump has already been interruptedAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-05-01Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull VFS updates from Al Viro, Misc cleanups all over the place, mainly wrt /proc interfaces (switch create_proc_entry to proc_create(), get rid of the deprecated create_proc_read_entry() in favor of using proc_create_data() and seq_file etc). 7kloc removed. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (204 commits) don't bother with deferred freeing of fdtables proc: Move non-public stuff from linux/proc_fs.h to fs/proc/internal.h proc: Make the PROC_I() and PDE() macros internal to procfs proc: Supply a function to remove a proc entry by PDE take cgroup_open() and cpuset_open() to fs/proc/base.c ppc: Clean up scanlog ppc: Clean up rtas_flash driver somewhat hostap: proc: Use remove_proc_subtree() drm: proc: Use remove_proc_subtree() drm: proc: Use minor->index to label things, not PDE->name drm: Constify drm_proc_list[] zoran: Don't print proc_dir_entry data in debug reiserfs: Don't access the proc_dir_entry in r_open(), r_start() r_show() proc: Supply an accessor for getting the data from a PDE's parent airo: Use remove_proc_subtree() rtl8192u: Don't need to save device proc dir PDE rtl8187se: Use a dir under /proc/net/r8180/ proc: Add proc_mkdir_data() proc: Move some bits from linux/proc_fs.h to linux/{of.h,signal.h,tty.h} proc: Move PDE_NET() to fs/proc/proc_net.c ...
2013-04-30coredump: change wait_for_dump_helpers() to use wait_event_interruptible()Oleg Nesterov
wait_for_dump_helpers() calls wake_up/kill_fasync from inside the wait_event-like loop. This is not needed and in fact this is not strictly correct, we can/should do this only once after we change pipe->writers. We could even check if it becomes zero. Change this code to use use wait_event_interruptible(), this can also help to make this wait freezable. With this patch we check pipe->readers without pipe_lock(), this is fine. Once we see pipe->readers == 1 we know that the handler decremented the counter, this is all we need. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Mandeep Singh Baines <msb@chromium.org> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30coredump: factor out the setting of PF_DUMPCOREOleg Nesterov
Cleanup. Every linux_binfmt->core_dump() sets PF_DUMPCORE, move this into zap_threads() called by do_coredump(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Mandeep Singh Baines <msb@chromium.org> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30coredump: introduce dump_interrupted()Oleg Nesterov
By discussion with Mandeep. Change dump_write(), dump_seek() and do_coredump() to check signal_pending() and abort if it is true. dump_seek() does this only before f_op->llseek(), otherwise it relies on dump_write(). We need this change to ensure that the coredump won't delay suspend, and to ensure it reacts to SIGKILL "quickly enough", a core dump can take a lot of time. In particular this can help oom-killer. We add the new trivial helper, dump_interrupted() to add the comments and to simplify the potential freezer changes. Perhaps it will have more callers. Ideally it should do try_to_freeze() but then we need the unpleasant changes in dump_write() and wait_for_dump_helpers(). It is not trivial to change dump_write() to restart if f_op->write() fails because of freezing(). We need to handle the short writes, we need to clear TIF_SIGPENDING (and we can't rely on recalc_sigpending() unless we change it to check PF_DUMPCORE). And if the buggy f_op->write() sets TIF_SIGPENDING we can not distinguish this case from the race with freeze_task() + __thaw_task(). So we simply accept the fact that the freezer can truncate a core-dump but at least you can reliably suspend. Hopefully we can tolerate this unlikely case and the necessary complications doesn't worth a trouble. But if we decide to make the coredumping freezable later we can do this on top of this change. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Mandeep Singh Baines <msb@chromium.org> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30coredump: sanitize the setting of signal->group_exit_codeOleg Nesterov
Now that the coredumping process can be SIGKILL'ed, the setting of ->group_exit_code in do_coredump() can race with complete_signal() and SIGKILL or 0x80 can be "lost", or wait(status) can report status == SIGKILL | 0x80. But the main problem is that it is not clear to me what should we do if binfmt->core_dump() succeeds but SIGKILL was sent, that is why this patch comes as a separate change. This patch adds 0x80 if ->core_dump() succeeds and the process was not killed. But perhaps we can (should?) re-set ->group_exit_code changed by SIGKILL back to "siginfo->si_signo |= 0x80" in case when core_dumped == T. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Tested-by: Mandeep Singh Baines <msb@chromium.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Roland McGrath <roland@hack.frob.com> Cc: Tejun Heo <tj@kernel.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>
2013-04-30coredump: ensure that SIGKILL always kills the dumping threadOleg Nesterov
prepare_signal() blesses SIGKILL sent to the dumping process but this signal can be "lost" anyway. The problems is, complete_signal() sees SIGNAL_GROUP_EXIT and skips the "kill them all" logic. And even if the dumping process is single-threaded (so the target is always "correct"), the group-wide SIGKILL is not recorded in task->pending and thus __fatal_signal_pending() won't be true. A multi-threaded case has even more problems. And even ignoring all technical details, SIGNAL_GROUP_EXIT doesn't look right to me. This coredumping process is not exiting yet, it can do a lot of work dumping the core. With this patch the dumping process doesn't have SIGNAL_GROUP_EXIT, we set signal->group_exit_task instead. This makes signal_group_exit() true and thus this should equally close the races with exit/exec/stop but allows to kill the dumping thread reliably. Notes: - It is not clear what should we do with ->group_exit_code if the dumper was killed, see the next change. - we need more (hopefully straightforward) changes to ensure that SIGKILL actually interrupts the coredump. Basically we need to check __fatal_signal_pending() in dump_write() and dump_seek(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Tested-by: Mandeep Singh Baines <msb@chromium.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Roland McGrath <roland@hack.frob.com> Cc: Tejun Heo <tj@kernel.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>