kernel/linux.git/fs/exec.c, branch linux-6.9.y

mm/ksm: fix ksm exec support for prctl

2024-05-30T07:44:56+00:00

[ Upstream commit 3a9e567ca45fb5280065283d10d9a11f0db61d2b ] Patch series "mm/ksm: fix ksm exec support for prctl", v4. commit 3c6f33b7273a ("mm/ksm: support fork/exec for prctl") inherits MMF_VM_MERGE_ANY flag when a task calls execve(). However, it doesn't create the mm_slot, so ksmd will not try to scan this task. The first patch fixes the issue. The second patch refactors to prepare for the third patch. The third patch extends the selftests of ksm to verfity the deduplication really happens after fork/exec inherits ths KSM setting. This patch (of 3): commit 3c6f33b7273a ("mm/ksm: support fork/exec for prctl") inherits MMF_VM_MERGE_ANY flag when a task calls execve(). Howerver, it doesn't create the mm_slot, so ksmd will not try to scan this task. To fix it, allocate and add the mm_slot to ksm_mm_head in __bprm_mm_init() when the mm has MMF_VM_MERGE_ANY flag. Link: https://lkml.kernel.org/r/20240328111010.1502191-1-tujinjiang@huawei.com Link: https://lkml.kernel.org/r/20240328111010.1502191-2-tujinjiang@huawei.com Fixes: 3c6f33b7273a ("mm/ksm: support fork/exec for prctl") Signed-off-by: Jinjiang Tu Reviewed-by: David Hildenbrand Cc: Johannes Weiner Cc: Kefeng Wang Cc: Nanyong Sun Cc: Rik van Riel Cc: Stefan Roesch Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

Merge tag 'execve-v6.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2024-03-27T16:57:30+00:00

Pull execve fixes from Kees Cook: - Fix selftests to conform to the TAP output format (Muhammad Usama Anjum) - Fix NOMMU linux_binprm::exec pointer in auxv (Max Filippov) - Replace deprecated strncpy usage (Justin Stitt) - Replace another /bin/sh instance in selftests * tag 'execve-v6.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: binfmt: replace deprecated strncpy exec: Fix NOMMU linux_binprm::exec in transfer_args_to_stack() selftests/exec: Convert remaining /bin/sh to /bin/bash selftests/exec: execveat: Improve debug reporting selftests/exec: recursion-depth: conform test to TAP format output selftests/exec: load_address: conform test to TAP format output selftests/exec: binfmt_script: Add the overall result line according to TAP

exec: Fix NOMMU linux_binprm::exec in transfer_args_to_stack()

2024-03-21T17:05:47+00:00

In NOMMU kernel the value of linux_binprm::p is the offset inside the temporary program arguments array maintained in separate pages in the linux_binprm::page. linux_binprm::exec being a copy of linux_binprm::p thus must be adjusted when that array is copied to the user stack. Without that adjustment the value passed by the NOMMU kernel to the ELF program in the AT_EXECFN entry of the aux array doesn't make any sense and it may break programs that try to access memory pointed to by that entry. Adjust linux_binprm::exec before the successful return from the transfer_args_to_stack(). Cc: Fixes: b6a2fea39318 ("mm: variable length argument support") Fixes: 5edc2a5123a7 ("binfmt_elf_fdpic: wire up AT_EXECFD, AT_EXECFN, AT_SECURE") Signed-off-by: Max Filippov Link: https://lore.kernel.org/r/20240320182607.1472887-1-jcmvbkbc@gmail.com Signed-off-by: Kees Cook

Merge tag 'execve-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2024-03-12T21:45:12+00:00

Pull execve updates from Kees Cook: - Drop needless error path code in remove_arg_zero() (Li kunyu, Kees Cook) - binfmt_elf_efpic: Don't use missing interpreter's properties (Max Filippov) - Use /bin/bash for execveat selftests * tag 'execve-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: exec: Simplify remove_arg_zero() error path selftests/exec: Perform script checks with /bin/bash exec: Delete unnecessary statements in remove_arg_zero() fs: binfmt_elf_efpic: don't use missing interpreter's properties

Merge tag 'vfs-6.9.pidfd' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-03-11T17:21:06+00:00

Pull pdfd updates from Christian Brauner: - Until now pidfds could only be created for thread-group leaders but not for threads. There was no technical reason for this. We simply had no users that needed support for this. Now we do have users that need support for this. This introduces a new PIDFD_THREAD flag for pidfd_open(). If that flag is set pidfd_open() creates a pidfd that refers to a specific thread. In addition, we now allow clone() and clone3() to be called with CLONE_PIDFD | CLONE_THREAD which wasn't possible before. A pidfd that refers to an individual thread differs from a pidfd that refers to a thread-group leader: (1) Pidfds are pollable. A task may poll a pidfd and get notified when the task has exited. For thread-group leader pidfds the polling task is woken if the thread-group is empty. In other words, if the thread-group leader task exits when there are still threads alive in its thread-group the polling task will not be woken when the thread-group leader exits but rather when the last thread in the thread-group exits. For thread-specific pidfds the polling task is woken if the thread exits. (2) Passing a thread-group leader pidfd to pidfd_send_signal() will generate thread-group directed signals like kill(2) does. Passing a thread-specific pidfd to pidfd_send_signal() will generate thread-specific signals like tgkill(2) does. The default scope of the signal is thus determined by the type of the pidfd. Since use-cases exist where the default scope of the provided pidfd needs to be overriden the following flags are added to pidfd_send_signal(): - PIDFD_SIGNAL_THREAD Send a thread-specific signal. - PIDFD_SIGNAL_THREAD_GROUP Send a thread-group directed signal. - PIDFD_SIGNAL_PROCESS_GROUP Send a process-group directed signal. The scope change will only work if the struct pid is actually used for this scope. For example, in order to send a thread-group directed signal the provided pidfd must be used as a thread-group leader and similarly for PIDFD_SIGNAL_PROCESS_GROUP the struct pid must be used as a process group leader. - Move pidfds from the anonymous inode infrastructure to a tiny pseudo filesystem. This will unblock further work that we weren't able to do simply because of the very justified limitations of anonymous inodes. Moving pidfds to a tiny pseudo filesystem allows for statx on pidfds to become useful for the first time. They can now be compared by inode number which are unique for the system lifetime. Instead of stashing struct pid in file->private_data we can now stash it in inode->i_private. This makes it possible to introduce concepts that operate on a process once all file descriptors have been closed. A concrete example is kill-on-last-close. Another side-effect is that file->private_data is now freed up for per-file options for pidfds. Now, each struct pid will refer to a different inode but the same struct pid will refer to the same inode if it's opened multiple times. In contrast to now where each struct pid refers to the same inode. The tiny pseudo filesystem is not visible anywhere in userspace exactly like e.g., pipefs and sockfs. There's no lookup, there's no complex inode operations, nothing. Dentries and inodes are always deleted when the last pidfd is closed. We allocate a new inode and dentry for each struct pid and we reuse that inode and dentry for all pidfds that refer to the same struct pid. The code is entirely optional and fairly small. If it's not selected we fallback to anonymous inodes. Heavily inspired by nsfs. The dentry and inode allocation mechanism is moved into generic infrastructure that is now shared between nsfs and pidfs. The path_from_stashed() helper must be provided with a stashing location, an inode number, a mount, and the private data that is supposed to be used and it will provide a path that can be passed to dentry_open(). The helper will try retrieve an existing dentry from the provided stashing location. If a valid dentry is found it is reused. If not a new one is allocated and we try to stash it in the provided location. If this fails we retry until we either find an existing dentry or the newly allocated dentry could be stashed. Subsequent openers of the same namespace or task are then able to reuse it. - Currently it is only possible to get notified when a task has exited, i.e., become a zombie and userspace gets notified with EPOLLIN. We now also support waiting until the task has been reaped, notifying userspace with EPOLLHUP. - Ensure that ESRCH is reported for getfd if a task is exiting instead of the confusing EBADF. - Various smaller cleanups to pidfd functions. * tag 'vfs-6.9.pidfd' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (23 commits) libfs: improve path_from_stashed() libfs: add stashed_dentry_prune() libfs: improve path_from_stashed() helper pidfs: convert to path_from_stashed() helper nsfs: convert to path_from_stashed() helper libfs: add path_from_stashed() pidfd: add pidfs pidfd: move struct pidfd_fops pidfd: allow to override signal scope in pidfd_send_signal() pidfd: change pidfd_send_signal() to respect PIDFD_THREAD signal: fill in si_code in prepare_kill_siginfo() selftests: add ESRCH tests for pidfd_getfd() pidfd: getfd should always report ESRCH if a task is exiting pidfd: clone: allow CLONE_THREAD | CLONE_PIDFD together pidfd: exit: kill the no longer used thread_group_exited() pidfd: change do_notify_pidfd() to use __wake_up(poll_to_key(EPOLLIN)) pid: kill the obsolete PIDTYPE_PID code in transfer_pid() pidfd: kill the no longer needed do_notify_pidfd() in de_thread() pidfd_poll: report POLLHUP when pid_task() == NULL pidfd: implement PIDFD_THREAD flag for pidfd_open() ...

exec: Simplify remove_arg_zero() error path

2024-03-09T21:46:30+00:00

We don't need the "out" label any more, so remove "ret" and return directly on error. Reviewed-by: Jan Kara Signed-off-by: Kees Cook --- Cc: Eric Biederman Cc: Alexander Viro Cc: Christian Brauner Cc: Jan Kara Cc: linux-mm@kvack.org Cc: linux-fsdevel@vger.kernel.org

exec: Delete unnecessary statements in remove_arg_zero()

2024-02-24T01:07:31+00:00

'ret=0; ' In actual operation, the ret was not modified, so this sentence can be removed. Signed-off-by: Li kunyu Link: https://lore.kernel.org/r/20240220052426.62018-1-kunyu@nfschina.com Signed-off-by: Kees Cook

pidfd: kill the no longer needed do_notify_pidfd() in de_thread()

2024-02-02T13:57:53+00:00

Now that __change_pid() does wake_up_all(&pid->wait_pidfd) we can kill do_notify_pidfd(leader) in de_thread(), it calls release_task(leader) right after that and this implies detach_pid(leader, PIDTYPE_PID). Signed-off-by: Oleg Nesterov Link: https://lore.kernel.org/r/20240202131248.GA26022@redhat.com Signed-off-by: Christian Brauner

pidfd: implement PIDFD_THREAD flag for pidfd_open()

2024-02-02T12:12:28+00:00

With this flag: - pidfd_open() doesn't require that the target task must be a thread-group leader - pidfd_poll() succeeds when the task exits and becomes a zombie (iow, passes exit_notify()), even if it is a leader and thread-group is not empty. This means that the behaviour of pidfd_poll(PIDFD_THREAD, pid-of-group-leader) is not well defined if it races with exec() from its sub-thread; pidfd_poll() can succeed or not depending on whether pidfd_task_exited() is called before or after exchange_tids(). Perhaps we can improve this behaviour later, pidfd_poll() can probably take sig->group_exec_task into account. But this doesn't really differ from the case when the leader exits before other threads (so pidfd_poll() succeeds) and then another thread execs and pidfd_poll() will block again. thread_group_exited() is no longer used, perhaps it can die. Co-developed-by: Tycho Andersen Signed-off-by: Oleg Nesterov Link: https://lore.kernel.org/r/20240131132602.GA23641@redhat.com Tested-by: Tycho Andersen Reviewed-by: Tycho Andersen Signed-off-by: Christian Brauner

Merge tag 'execve-v6.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2024-01-24T21:32:29+00:00

Pull execve fixes from Kees Cook: - Fix error handling in begin_new_exec() (Bernd Edlinger) - MAINTAINERS: specifically mention ELF (Alexey Dobriyan) - Various cleanups related to earlier open() (Askar Safin, Kees Cook) * tag 'execve-v6.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: exec: Distinguish in_execve from in_exec exec: Fix error handling in begin_new_exec() exec: Add do_close_execat() helper exec: remove useless comment ELF, MAINTAINERS: specifically mention ELF