kernel/linux.git/include/linux/coredump.h, branch v6.6.132

coredump: hand a pidfd to the usermode coredump helper

2025-06-04T12:42:24+00:00

commit b5325b2a270fcaf7b2a9a0f23d422ca8a5a8bdea upstream. Give userspace a way to instruct the kernel to install a pidfd into the usermode helper process. This makes coredump handling a lot more reliable for userspace. In parallel with this commit we already have systemd adding support for this in [1]. We create a pidfs file for the coredumping process when we process the corename pattern. When the usermode helper process is forked we then install the pidfs file as file descriptor three into the usermode helpers file descriptor table so it's available to the exec'd program. Since usermode helpers are either children of the system_unbound_wq workqueue or kthreadd we know that the file descriptor table is empty and can thus always use three as the file descriptor number. Note, that we'll install a pidfd for the thread-group leader even if a subthread is calling do_coredump(). We know that task linkage hasn't been removed due to delay_group_leader() and even if this @current isn't the actual thread-group leader we know that the thread-group leader cannot be reaped until @current has exited. [brauner: This is a backport for the v6.6 series. Upsteam has significantly changed and backporting all that infra is a non-starter. So simply use the pidfd_prepare() helper and waste the file descriptor we allocated. Then we minimally massage the umh coredump setup code.] Link: https://github.com/systemd/systemd/pull/37125 [1] Link: https://lore.kernel.org/20250414-work-coredump-v2-3-685bf231f828@kernel.org Tested-by: Luca Boccassi Reviewed-by: Oleg Nesterov Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

Merge tag 'pull-elfcore' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2022-12-13T02:18:34+00:00

Pull elf coredumping updates from Al Viro: "Unification of regset and non-regset sides of ELF coredump handling. Collecting per-thread register values is the only thing that needs to be ifdefed there..." * tag 'pull-elfcore' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: [elf] get rid of get_note_info_size() [elf] unify regset and non-regset cases [elf][non-regset] use elf_core_copy_task_regs() for dumper as well [elf][non-regset] uninline elf_core_copy_task_fpregs() (and lose pt_regs argument) elf_core_copy_task_regs(): task_pt_regs is defined everywhere [elf][regset] simplify thread list handling in fill_note_info() [elf][regset] clean fill_note_info() a bit kill extern of vsyscall32_sysctl kill coredump_params->regs kill signal_pt_regs()

core_pattern: add CPU specifier

2022-11-18T21:55:06+00:00

Statistically, in a large deployment regular segfaults may indicate a CPU issue. Currently, it is not possible to find out what CPU the segfault happened on. There are at least two attempts to improve segfault logging with this regard, but they do not help in case the logs rotate. Hence, lets make sure it is possible to permanently record a CPU the task ran on using a new core_pattern specifier. Link: https://lkml.kernel.org/r/20220903064330.20772-1-oleksandr@redhat.com Signed-off-by: Oleksandr Natalenko Suggested-by: Renaud Métrich Reviewed-by: Oleg Nesterov Cc: Alexander Viro Cc: "Eric W . Biederman" Cc: Grzegorz Halat Cc: "Guilherme G. Piccoli" Cc: "Huang, Ying" Cc: Jason A. Donenfeld Cc: Joel Savitz Cc: Jonathan Corbet Cc: Kees Cook Cc: Laurent Dufour Cc: Luis Chamberlain Cc: Rob Herring Cc: Stephen Kitt Cc: Will Deacon Cc: Xiaoming Ni Signed-off-by: Andrew Morton

kill coredump_params->regs

2022-10-23T22:06:55+00:00

it's always task_pt_regs(current) Signed-off-by: Al Viro

coredump: Use the vma snapshot in fill_files_note

2022-03-08T19:04:19+00:00

Matthew Wilcox reported that there is a missing mmap_lock in file_files_note that could possibly lead to a user after free. Solve this by using the existing vma snapshot for consistency and to avoid the need to take the mmap_lock anywhere in the coredump code except for dump_vma_snapshot. Update the dump_vma_snapshot to capture vm_pgoff and vm_file that are neeeded by fill_files_note. Add free_vma_snapshot to free the captured values of vm_file. Reported-by: Matthew Wilcox Link: https://lkml.kernel.org/r/20220131153740.2396974-1-willy@infradead.org Cc: stable@vger.kernel.org Fixes: a07279c9a8cd ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot") Fixes: 2aa362c49c31 ("coredump: extend core dump note section to contain file names of mapped files") Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman"

coredump: Snapshot the vmas in do_coredump

2022-03-08T18:55:29+00:00

Move the call of dump_vma_snapshot and kvfree(vma_meta) out of the individual coredump routines into do_coredump itself. This makes the code less error prone and easier to maintain. Make the vma snapshot available to the coredump routines in struct coredump_params. This makes it easier to change and update what is captures in the vma snapshot and will be needed for fixing fill_file_notes. Reviewed-by: Jann Horn Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman"

coredump: Move definition of struct coredump_params into coredump.h

2022-03-08T18:50:58+00:00

Move the definition of struct coredump_params into coredump.h where it belongs. Remove the slightly errorneous comment explaining why struct coredump_params was declared in binfmts.h. Signed-off-by: "Eric W. Biederman"

fs/coredump: move coredump sysctls into its own file

2022-01-22T06:33:36+00:00

This moves the fs/coredump.c respective sysctls to its own file. Link: https://lkml.kernel.org/r/20211129211943.640266-6-mcgrof@kernel.org Signed-off-by: Xiaoming Ni Signed-off-by: Luis Chamberlain Cc: Al Viro Cc: Anil S Keshavamurthy Cc: Antti Palosaari Cc: Christian Brauner Cc: "David S. Miller" Cc: Eric Biederman Cc: Eric Biggers Cc: Iurii Zaikin Cc: Kees Cook Cc: Lukas Middendorf Cc: Masami Hiramatsu Cc: "Naveen N. Rao" Cc: Stephen Kitt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

coredump.h: move CONFIG_COREDUMP-only stuff inside the ifdef

2021-03-08T15:21:11+00:00

Signed-off-by: Al Viro

coredump: don't bother with do_truncate()

2021-03-08T15:21:11+00:00

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