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2024-06-21fs: add file and path permissions helpersChristian Brauner1-1/+1
[ Upstream commit 02f92b3868a1b34ab98464e76b0e4e060474ba10 ] Add two simple helpers to check permissions on a file and path respectively and convert over some callers. It simplifies quite a few codepaths and also reduces the churn in later patches quite a bit. Christoph also correctly points out that this makes codepaths (e.g. ioctls) way easier to follow that would otherwise have to do more complex argument passing than necessary. Link: https://lore.kernel.org/r/20210121131959.646623-4-christian.brauner@ubuntu.com Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Suggested-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-03-15getrusage: use sig->stats_lock rather than lock_task_sighand()Oleg Nesterov1-3/+13
[ Upstream commit f7ec1cd5cc7ef3ad964b677ba82b8b77f1c93009 ] lock_task_sighand() can trigger a hard lockup. If NR_CPUS threads call getrusage() at the same time and the process has NR_THREADS, spin_lock_irq will spin with irqs disabled O(NR_CPUS * NR_THREADS) time. Change getrusage() to use sig->stats_lock, it was specifically designed for this type of use. This way it runs lockless in the likely case. TODO: - Change do_task_stat() to use sig->stats_lock too, then we can remove spin_lock_irq(siglock) in wait_task_zombie(). - Turn sig->stats_lock into seqcount_rwlock_t, this way the readers in the slow mode won't exclude each other. See https://lore.kernel.org/all/20230913154907.GA26210@redhat.com/ - stats_lock has to disable irqs because ->siglock can be taken in irq context, it would be very nice to change __exit_signal() to avoid the siglock->stats_lock dependency. Link: https://lkml.kernel.org/r/20240122155053.GA26214@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Dylan Hatch <dylanbhatch@google.com> Tested-by: Dylan Hatch <dylanbhatch@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-03-15getrusage: use __for_each_thread()Oleg Nesterov1-3/+1
[ Upstream commit 13b7bc60b5353371460a203df6c38ccd38ad7a3a ] do/while_each_thread should be avoided when possible. Plus this change allows to avoid lock_task_sighand(), we can use rcu and/or sig->stats_lock instead. Link: https://lkml.kernel.org/r/20230909172629.GA20454@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Stable-dep-of: f7ec1cd5cc7e ("getrusage: use sig->stats_lock rather than lock_task_sighand()") Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-03-15getrusage: move thread_group_cputime_adjusted() outside of lock_task_sighand()Oleg Nesterov1-15/+19
[ Upstream commit daa694e4137571b4ebec330f9a9b4d54aa8b8089 ] Patch series "getrusage: use sig->stats_lock", v2. This patch (of 2): thread_group_cputime() does its own locking, we can safely shift thread_group_cputime_adjusted() which does another for_each_thread loop outside of ->siglock protected section. This is also preparation for the next patch which changes getrusage() to use stats_lock instead of siglock, thread_group_cputime() takes the same lock. With the current implementation recursive read_seqbegin_or_lock() is fine, thread_group_cputime() can't enter the slow mode if the caller holds stats_lock, yet this looks more safe and better performance-wise. Link: https://lkml.kernel.org/r/20240122155023.GA26169@redhat.com Link: https://lkml.kernel.org/r/20240122155050.GA26205@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Dylan Hatch <dylanbhatch@google.com> Tested-by: Dylan Hatch <dylanbhatch@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-03-15getrusage: add the "signal_struct *sig" local variableOleg Nesterov1-18/+19
[ Upstream commit c7ac8231ace9b07306d0299969e42073b189c70a ] No functional changes, cleanup/preparation. Link: https://lkml.kernel.org/r/20230909172554.GA20441@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Stable-dep-of: daa694e41375 ("getrusage: move thread_group_cputime_adjusted() outside of lock_task_sighand()") Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-04-26kernel/sys.c: fix and improve control flow in __sys_setres[ug]id()Ondrej Mosnacek1-29/+40
commit 659c0ce1cb9efc7f58d380ca4bb2a51ae9e30553 upstream. Linux Security Modules (LSMs) that implement the "capable" hook will usually emit an access denial message to the audit log whenever they "block" the current task from using the given capability based on their security policy. The occurrence of a denial is used as an indication that the given task has attempted an operation that requires the given access permission, so the callers of functions that perform LSM permission checks must take care to avoid calling them too early (before it is decided if the permission is actually needed to perform the requested operation). The __sys_setres[ug]id() functions violate this convention by first calling ns_capable_setid() and only then checking if the operation requires the capability or not. It means that any caller that has the capability granted by DAC (task's capability set) but not by MAC (LSMs) will generate a "denied" audit record, even if is doing an operation for which the capability is not required. Fix this by reordering the checks such that ns_capable_setid() is checked last and -EPERM is returned immediately if it returns false. While there, also do two small optimizations: * move the capability check before prepare_creds() and * bail out early in case of a no-op. Link: https://lkml.kernel.org/r/20230217162154.837549-1-omosnace@redhat.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-24prlimit: do_prlimit needs to have a speculation checkGreg Kroah-Hartman1-0/+2
commit 739790605705ddcf18f21782b9c99ad7d53a8c11 upstream. do_prlimit() adds the user-controlled resource value to a pointer that will subsequently be dereferenced. In order to help prevent this codepath from being used as a spectre "gadget" a barrier needs to be added after checking the range. Reported-by: Jordy Zomer <jordyzomer@google.com> Tested-by: Jordy Zomer <jordyzomer@google.com> Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-09-26prctl: allow to setup brk for et_dyn executablesCyrill Gorcunov1-7/+0
commit e1fbbd073137a9d63279f6bf363151a938347640 upstream. Keno Fischer reported that when a binray loaded via ld-linux-x the prctl(PR_SET_MM_MAP) doesn't allow to setup brk value because it lays before mm:end_data. For example a test program shows | # ~/t | | start_code 401000 | end_code 401a15 | start_stack 7ffce4577dd0 | start_data 403e10 | end_data 40408c | start_brk b5b000 | sbrk(0) b5b000 and when executed via ld-linux | # /lib64/ld-linux-x86-64.so.2 ~/t | | start_code 7fc25b0a4000 | end_code 7fc25b0c4524 | start_stack 7fffcc6b2400 | start_data 7fc25b0ce4c0 | end_data 7fc25b0cff98 | start_brk 55555710c000 | sbrk(0) 55555710c000 This of course prevent criu from restoring such programs. Looking into how kernel operates with brk/start_brk inside brk() syscall I don't see any problem if we allow to setup brk/start_brk without checking for end_data. Even if someone pass some weird address here on a purpose then the worst possible result will be an unexpected unmapping of existing vma (own vma, since prctl works with the callers memory) but test for RLIMIT_DATA is still valid and a user won't be able to gain more memory in case of expanding VMAs via new values shipped with prctl call. Link: https://lkml.kernel.org/r/20210121221207.GB2174@grain Fixes: bbdc6076d2e5 ("binfmt_elf: move brk out of mmap when doing direct loader exec") Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> Reported-by: Keno Fischer <keno@juliacomputing.com> Acked-by: Andrey Vagin <avagin@gmail.com> Tested-by: Andrey Vagin <avagin@gmail.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com> Cc: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-09-08Revert "Add a reference to ucounts for each cred"Greg Kroah-Hartman1-12/+0
This reverts commit b2c4d9a33cc2dec7466f97eba2c4dd571ad798a5 which is commit 905ae01c4ae2ae3df05bb141801b1db4b7d83c61 upstream. This commit should not have been applied to the 5.10.y stable tree, so revert it. Reported-by: "Eric W. Biederman" <ebiederm@xmission.com> Link: https://lore.kernel.org/r/87v93k4bl6.fsf@disp2133 Cc: Alexey Gladkov <legion@kernel.org> Cc: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-14Add a reference to ucounts for each credAlexey Gladkov1-0/+12
[ Upstream commit 905ae01c4ae2ae3df05bb141801b1db4b7d83c61 ] For RLIMIT_NPROC and some other rlimits the user_struct that holds the global limit is kept alive for the lifetime of a process by keeping it in struct cred. Adding a pointer to ucounts in the struct cred will allow to track RLIMIT_NPROC not only for user in the system, but for user in the user_namespace. Updating ucounts may require memory allocation which may fail. So, we cannot change cred.ucounts in the commit_creds() because this function cannot fail and it should always return 0. For this reason, we modify cred.ucounts before calling the commit_creds(). Changelog v6: * Fix null-ptr-deref in is_ucounts_overlimit() detected by trinity. This error was caused by the fact that cred_alloc_blank() left the ucounts pointer empty. Reported-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Alexey Gladkov <legion@kernel.org> Link: https://lkml.kernel.org/r/b37aaef28d8b9b0d757e07ba6dd27281bbe39259.1619094428.git.legion@kernel.org Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-25kernel/sys.c: fix prototype of prctl_get_tid_address()Rasmus Villemoes1-3/+3
tid_addr is not a "pointer to (pointer to int in userspace)"; it is in fact a "pointer to (pointer to int in userspace) in userspace". So sparse rightfully complains about passing a kernel pointer to put_user(). Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-25Merge tag 'safesetid-5.10' of git://github.com/micah-morton/linuxLinus Torvalds1-5/+5
Pull SafeSetID updates from Micah Morton: "The changes are mostly contained to within the SafeSetID LSM, with the exception of a few 1-line changes to change some ns_capable() calls to ns_capable_setid() -- causing a flag (CAP_OPT_INSETID) to be set that is examined by SafeSetID code and nothing else in the kernel. The changes to SafeSetID internally allow for setting up GID transition security policies, as already existed for UIDs" * tag 'safesetid-5.10' of git://github.com/micah-morton/linux: LSM: SafeSetID: Fix warnings reported by test bot LSM: SafeSetID: Add GID security policy handling LSM: Signal to SafeSetID when setting group IDs
2020-10-16kernel/sys.c: replace do_brk with do_brk_flags in comment of prctl_set_mm_map()Liao Pingfang1-1/+1
Replace do_brk with do_brk_flags in comment of prctl_set_mm_map(), since do_brk was removed in following commit. Fixes: bb177a732c4369 ("mm: do not bug_on on incorrect length in __mm_populate()") Signed-off-by: Liao Pingfang <liao.pingfang@zte.com.cn> Signed-off-by: Yi Wang <wang.yi59@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: https://lkml.kernel.org/r/1600650751-43127-1-git-send-email-wang.yi59@zte.com.cn Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-13LSM: Signal to SafeSetID when setting group IDsThomas Cedeno1-5/+5
For SafeSetID to properly gate set*gid() calls, it needs to know whether ns_capable() is being called from within a sys_set*gid() function or is being called from elsewhere in the kernel. This allows SafeSetID to deny CAP_SETGID to restricted groups when they are attempting to use the capability for code paths other than updating GIDs (e.g. setting up userns GID mappings). This is the identical approach to what is currently done for CAP_SETUID. NOTE: We also add signaling to SafeSetID from the setgroups() syscall, as we have future plans to restrict a process' ability to set supplementary groups in addition to what is added in this series for restricting setting of the primary group. Signed-off-by: Thomas Cedeno <thomascedeno@google.com> Signed-off-by: Micah Morton <mortonm@chromium.org>
2020-08-23treewide: Use fallthrough pseudo-keywordGustavo A. R. Silva1-1/+1
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-07-19prctl: exe link permission error changed from -EINVAL to -EPERMNicolas Viennot1-1/+1
This brings consistency with the rest of the prctl() syscall where -EPERM is returned when failing a capability check. Signed-off-by: Nicolas Viennot <Nicolas.Viennot@twosigma.com> Signed-off-by: Adrian Reber <areber@redhat.com> Reviewed-by: Serge Hallyn <serge@hallyn.com> Link: https://lore.kernel.org/r/20200719100418.2112740-7-areber@redhat.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2020-07-19prctl: Allow local CAP_CHECKPOINT_RESTORE to change /proc/self/exeNicolas Viennot1-4/+7
Originally, only a local CAP_SYS_ADMIN could change the exe link, making it difficult for doing checkpoint/restore without CAP_SYS_ADMIN. This commit adds CAP_CHECKPOINT_RESTORE in addition to CAP_SYS_ADMIN for permitting changing the exe link. The following describes the history of the /proc/self/exe permission checks as it may be difficult to understand what decisions lead to this point. * [1] May 2012: This commit introduces the ability of changing /proc/self/exe if the user is CAP_SYS_RESOURCE capable. In the related discussion [2], no clear thread model is presented for what could happen if the /proc/self/exe changes multiple times, or why would the admin be at the mercy of userspace. * [3] Oct 2014: This commit introduces a new API to change /proc/self/exe. The permission no longer checks for CAP_SYS_RESOURCE, but instead checks if the current user is root (uid=0) in its local namespace. In the related discussion [4] it is said that "Controlling exe_fd without privileges may turn out to be dangerous. At least things like tomoyo examine it for making policy decisions (see tomoyo_manager())." * [5] Dec 2016: This commit removes the restriction to change /proc/self/exe at most once. The related discussion [6] informs that the audit subsystem relies on the exe symlink, presumably audit_log_d_path_exe() in kernel/audit.c. * [7] May 2017: This commit changed the check from uid==0 to local CAP_SYS_ADMIN. No discussion. * [8] July 2020: A PoC to spoof any program's /proc/self/exe via ptrace is demonstrated Overall, the concrete points that were made to retain capability checks around changing the exe symlink is that tomoyo_manager() and audit_log_d_path_exe() uses the exe_file path. Christian Brauner said that relying on /proc/<pid>/exe being immutable (or guarded by caps) in a sake of security is a bit misleading. It can only be used as a hint without any guarantees of what code is being executed once execve() returns to userspace. Christian suggested that in the future, we could call audit_log() or similar to inform the admin of all exe link changes, instead of attempting to provide security guarantees via permission checks. However, this proposed change requires the understanding of the security implications in the tomoyo/audit subsystems. [1] b32dfe377102 ("c/r: prctl: add ability to set new mm_struct::exe_file") [2] https://lore.kernel.org/patchwork/patch/292515/ [3] f606b77f1a9e ("prctl: PR_SET_MM -- introduce PR_SET_MM_MAP operation") [4] https://lore.kernel.org/patchwork/patch/479359/ [5] 3fb4afd9a504 ("prctl: remove one-shot limitation for changing exe link") [6] https://lore.kernel.org/patchwork/patch/697304/ [7] 4d28df6152aa ("prctl: Allow local CAP_SYS_ADMIN changing exe_file") [8] https://github.com/nviennot/run_as_exe Signed-off-by: Nicolas Viennot <Nicolas.Viennot@twosigma.com> Signed-off-by: Adrian Reber <areber@redhat.com> Link: https://lore.kernel.org/r/20200719100418.2112740-6-areber@redhat.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2020-06-14Merge tag 'LSM-add-setgid-hook-5.8-author-fix' of ↵Linus Torvalds1-1/+14
git://github.com/micah-morton/linux Pull SafeSetID update from Micah Morton: "Add additional LSM hooks for SafeSetID SafeSetID is capable of making allow/deny decisions for set*uid calls on a system, and we want to add similar functionality for set*gid calls. The work to do that is not yet complete, so probably won't make it in for v5.8, but we are looking to get this simple patch in for v5.8 since we have it ready. We are planning on the rest of the work for extending the SafeSetID LSM being merged during the v5.9 merge window" * tag 'LSM-add-setgid-hook-5.8-author-fix' of git://github.com/micah-morton/linux: security: Add LSM hooks to set*gid syscalls
2020-06-14security: Add LSM hooks to set*gid syscallsThomas Cedeno1-1/+14
The SafeSetID LSM uses the security_task_fix_setuid hook to filter set*uid() syscalls according to its configured security policy. In preparation for adding analagous support in the LSM for set*gid() syscalls, we add the requisite hook here. Tested by putting print statements in the security_task_fix_setgid hook and seeing them get hit during kernel boot. Signed-off-by: Thomas Cedeno <thomascedeno@google.com> Signed-off-by: Micah Morton <mortonm@chromium.org>
2020-06-09mmap locking API: convert mmap_sem commentsMichel Lespinasse1-2/+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>
2020-06-09mmap locking API: use coccinelle to convert mmap_sem rwsem call sitesMichel Lespinasse1-9/+9
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>
2020-06-02Merge branch 'akpm' (patches from Andrew)Linus Torvalds1-1/+1
Merge updates from Andrew Morton: "A few little subsystems and a start of a lot of MM patches. Subsystems affected by this patch series: squashfs, ocfs2, parisc, vfs. With mm subsystems: slab-generic, slub, debug, pagecache, gup, swap, memcg, pagemap, memory-failure, vmalloc, kasan" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (128 commits) kasan: move kasan_report() into report.c mm/mm_init.c: report kasan-tag information stored in page->flags ubsan: entirely disable alignment checks under UBSAN_TRAP kasan: fix clang compilation warning due to stack protector x86/mm: remove vmalloc faulting mm: remove vmalloc_sync_(un)mappings() x86/mm/32: implement arch_sync_kernel_mappings() x86/mm/64: implement arch_sync_kernel_mappings() mm/ioremap: track which page-table levels were modified mm/vmalloc: track which page-table levels were modified mm: add functions to track page directory modifications s390: use __vmalloc_node in stack_alloc powerpc: use __vmalloc_node in alloc_vm_stack arm64: use __vmalloc_node in arch_alloc_vmap_stack mm: remove vmalloc_user_node_flags mm: switch the test_vmalloc module to use __vmalloc_node mm: remove __vmalloc_node_flags_caller mm: remove both instances of __vmalloc_node_flags mm: remove the prot argument to __vmalloc_node mm: remove the pgprot argument to __vmalloc ...
2020-06-02mm/writeback: replace PF_LESS_THROTTLE with PF_LOCAL_THROTTLENeilBrown1-1/+1
PF_LESS_THROTTLE exists for loop-back nfsd (and a similar need in the loop block driver and callers of prctl(PR_SET_IO_FLUSHER)), where a daemon needs to write to one bdi (the final bdi) in order to free up writes queued to another bdi (the client bdi). The daemon sets PF_LESS_THROTTLE and gets a larger allowance of dirty pages, so that it can still dirty pages after other processses have been throttled. The purpose of this is to avoid deadlock that happen when the PF_LESS_THROTTLE process must write for any dirty pages to be freed, but it is being thottled and cannot write. This approach was designed when all threads were blocked equally, independently on which device they were writing to, or how fast it was. Since that time the writeback algorithm has changed substantially with different threads getting different allowances based on non-trivial heuristics. This means the simple "add 25%" heuristic is no longer reliable. The important issue is not that the daemon needs a *larger* dirty page allowance, but that it needs a *private* dirty page allowance, so that dirty pages for the "client" bdi that it is helping to clear (the bdi for an NFS filesystem or loop block device etc) do not affect the throttling of the daemon writing to the "final" bdi. This patch changes the heuristic so that the task is not throttled when the bdi it is writing to has a dirty page count below below (or equal to) the free-run threshold for that bdi. This ensures it will always be able to have some pages in flight, and so will not deadlock. In a steady-state, it is expected that PF_LOCAL_THROTTLE tasks might still be throttled by global threshold, but that is acceptable as it is only the deadlock state that is interesting for this flag. This approach of "only throttle when target bdi is busy" is consistent with the other use of PF_LESS_THROTTLE in current_may_throttle(), were it causes attention to be focussed only on the target bdi. So this patch - renames PF_LESS_THROTTLE to PF_LOCAL_THROTTLE, - removes the 25% bonus that that flag gives, and - If PF_LOCAL_THROTTLE is set, don't delay at all unless the global and the local free-run thresholds are exceeded. Note that previously realtime threads were treated the same as PF_LESS_THROTTLE threads. This patch does *not* change the behvaiour for real-time threads, so it is now different from the behaviour of nfsd and loop tasks. I don't know what is wanted for realtime. [akpm@linux-foundation.org: coding style fixes] Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Chuck Lever <chuck.lever@oracle.com> [nfsd] Cc: Christoph Hellwig <hch@lst.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Link: http://lkml.kernel.org/r/87ftbf7gs3.fsf@notabene.neil.brown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-25compat sysinfo(2): don't bother with field-by-field copyoutAl Viro1-16/+17
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-03-03sys/sysinfo: Respect boottime inside time namespaceCyril Hrubis1-0/+2
The sysinfo() syscall includes uptime in seconds but has no correction for time namespaces which makes it inconsistent with the /proc/uptime inside of a time namespace. Add the missing time namespace adjustment call. Signed-off-by: Cyril Hrubis <chrubis@suse.cz> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Dmitry Safonov <dima@arista.com> Link: https://lkml.kernel.org/r/20200303150638.7329-1-chrubis@suse.cz
2020-01-28prctl: PR_{G,S}ET_IO_FLUSHER to support controlling memory reclaimMike Christie1-0/+25
There are several storage drivers like dm-multipath, iscsi, tcmu-runner, amd nbd that have userspace components that can run in the IO path. For example, iscsi and nbd's userspace deamons may need to recreate a socket and/or send IO on it, and dm-multipath's daemon multipathd may need to send SG IO or read/write IO to figure out the state of paths and re-set them up. In the kernel these drivers have access to GFP_NOIO/GFP_NOFS and the memalloc_*_save/restore functions to control the allocation behavior, but for userspace we would end up hitting an allocation that ended up writing data back to the same device we are trying to allocate for. The device is then in a state of deadlock, because to execute IO the device needs to allocate memory, but to allocate memory the memory layers want execute IO to the device. Here is an example with nbd using a local userspace daemon that performs network IO to a remote server. We are using XFS on top of the nbd device, but it can happen with any FS or other modules layered on top of the nbd device that can write out data to free memory. Here a nbd daemon helper thread, msgr-worker-1, is performing a write/sendmsg on a socket to execute a request. This kicks off a reclaim operation which results in a WRITE to the nbd device and the nbd thread calling back into the mm layer. [ 1626.609191] msgr-worker-1 D 0 1026 1 0x00004000 [ 1626.609193] Call Trace: [ 1626.609195] ? __schedule+0x29b/0x630 [ 1626.609197] ? wait_for_completion+0xe0/0x170 [ 1626.609198] schedule+0x30/0xb0 [ 1626.609200] schedule_timeout+0x1f6/0x2f0 [ 1626.609202] ? blk_finish_plug+0x21/0x2e [ 1626.609204] ? _xfs_buf_ioapply+0x2e6/0x410 [ 1626.609206] ? wait_for_completion+0xe0/0x170 [ 1626.609208] wait_for_completion+0x108/0x170 [ 1626.609210] ? wake_up_q+0x70/0x70 [ 1626.609212] ? __xfs_buf_submit+0x12e/0x250 [ 1626.609214] ? xfs_bwrite+0x25/0x60 [ 1626.609215] xfs_buf_iowait+0x22/0xf0 [ 1626.609218] __xfs_buf_submit+0x12e/0x250 [ 1626.609220] xfs_bwrite+0x25/0x60 [ 1626.609222] xfs_reclaim_inode+0x2e8/0x310 [ 1626.609224] xfs_reclaim_inodes_ag+0x1b6/0x300 [ 1626.609227] xfs_reclaim_inodes_nr+0x31/0x40 [ 1626.609228] super_cache_scan+0x152/0x1a0 [ 1626.609231] do_shrink_slab+0x12c/0x2d0 [ 1626.609233] shrink_slab+0x9c/0x2a0 [ 1626.609235] shrink_node+0xd7/0x470 [ 1626.609237] do_try_to_free_pages+0xbf/0x380 [ 1626.609240] try_to_free_pages+0xd9/0x1f0 [ 1626.609245] __alloc_pages_slowpath+0x3a4/0xd30 [ 1626.609251] ? ___slab_alloc+0x238/0x560 [ 1626.609254] __alloc_pages_nodemask+0x30c/0x350 [ 1626.609259] skb_page_frag_refill+0x97/0xd0 [ 1626.609274] sk_page_frag_refill+0x1d/0x80 [ 1626.609279] tcp_sendmsg_locked+0x2bb/0xdd0 [ 1626.609304] tcp_sendmsg+0x27/0x40 [ 1626.609307] sock_sendmsg+0x54/0x60 [ 1626.609308] ___sys_sendmsg+0x29f/0x320 [ 1626.609313] ? sock_poll+0x66/0xb0 [ 1626.609318] ? ep_item_poll.isra.15+0x40/0xc0 [ 1626.609320] ? ep_send_events_proc+0xe6/0x230 [ 1626.609322] ? hrtimer_try_to_cancel+0x54/0xf0 [ 1626.609324] ? ep_read_events_proc+0xc0/0xc0 [ 1626.609326] ? _raw_write_unlock_irq+0xa/0x20 [ 1626.609327] ? ep_scan_ready_list.constprop.19+0x218/0x230 [ 1626.609329] ? __hrtimer_init+0xb0/0xb0 [ 1626.609331] ? _raw_spin_unlock_irq+0xa/0x20 [ 1626.609334] ? ep_poll+0x26c/0x4a0 [ 1626.609337] ? tcp_tsq_write.part.54+0xa0/0xa0 [ 1626.609339] ? release_sock+0x43/0x90 [ 1626.609341] ? _raw_spin_unlock_bh+0xa/0x20 [ 1626.609342] __sys_sendmsg+0x47/0x80 [ 1626.609347] do_syscall_64+0x5f/0x1c0 [ 1626.609349] ? prepare_exit_to_usermode+0x75/0xa0 [ 1626.609351] entry_SYSCALL_64_after_hwframe+0x44/0xa9 This patch adds a new prctl command that daemons can use after they have done their initial setup, and before they start to do allocations that are in the IO path. It sets the PF_MEMALLOC_NOIO and PF_LESS_THROTTLE flags so both userspace block and FS threads can use it to avoid the allocation recursion and try to prevent from being throttled while writing out data to free up memory. Signed-off-by: Mike Christie <mchristi@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Tested-by: Masato Suzuki <masato.suzuki@wdc.com> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Link: https://lore.kernel.org/r/20191112001900.9206-1-mchristi@redhat.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2019-12-04kernel/sys.c: avoid copying possible padding bytes in copy_to_userJoe Perches1-1/+3
Initialization is not guaranteed to zero padding bytes so use an explicit memset instead to avoid leaking any kernel content in any possible padding bytes. Link: http://lkml.kernel.org/r/dfa331c00881d61c8ee51577a082d8bebd61805c.camel@perches.com Signed-off-by: Joe Perches <joe@perches.com> Cc: Dan Carpenter <error27@gmail.com> Cc: Julia Lawall <julia.lawall@lip6.fr> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-11-15y2038: rusage: use __kernel_old_timevalArnd Bergmann1-2/+2
There are two 'struct timeval' fields in 'struct rusage'. Unfortunately the definition of timeval is now ambiguous when used in user space with a libc that has a 64-bit time_t, and this also changes the 'rusage' definition in user space in a way that is incompatible with the system call interface. While there is no good solution to avoid all ambiguity here, change the definition in the kernel headers to be compatible with the kernel ABI, using __kernel_old_timeval as an unambiguous base type. In previous discussions, there was also a plan to add a replacement for rusage based on 64-bit timestamps and nanosecond resolution, i.e. 'struct __kernel_timespec'. I have patches for that as well, if anyone thinks we should do that. Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2019-09-17Merge branch 'timers-core-for-linus' of ↵Linus Torvalds1-13/+3
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core timer updates from Thomas Gleixner: "Timers and timekeeping updates: - A large overhaul of the posix CPU timer code which is a preparation for moving the CPU timer expiry out into task work so it can be properly accounted on the task/process. An update to the bogus permission checks will come later during the merge window as feedback was not complete before heading of for travel. - Switch the timerqueue code to use cached rbtrees and get rid of the homebrewn caching of the leftmost node. - Consolidate hrtimer_init() + hrtimer_init_sleeper() calls into a single function - Implement the separation of hrtimers to be forced to expire in hard interrupt context even when PREEMPT_RT is enabled and mark the affected timers accordingly. - Implement a mechanism for hrtimers and the timer wheel to protect RT against priority inversion and live lock issues when a (hr)timer which should be canceled is currently executing the callback. Instead of infinitely spinning, the task which tries to cancel the timer blocks on a per cpu base expiry lock which is held and released by the (hr)timer expiry code. - Enable the Hyper-V TSC page based sched_clock for Hyper-V guests resulting in faster access to timekeeping functions. - Updates to various clocksource/clockevent drivers and their device tree bindings. - The usual small improvements all over the place" * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (101 commits) posix-cpu-timers: Fix permission check regression posix-cpu-timers: Always clear head pointer on dequeue hrtimer: Add a missing bracket and hide `migration_base' on !SMP posix-cpu-timers: Make expiry_active check actually work correctly posix-timers: Unbreak CONFIG_POSIX_TIMERS=n build tick: Mark sched_timer to expire in hard interrupt context hrtimer: Add kernel doc annotation for HRTIMER_MODE_HARD x86/hyperv: Hide pv_ops access for CONFIG_PARAVIRT=n posix-cpu-timers: Utilize timerqueue for storage posix-cpu-timers: Move state tracking to struct posix_cputimers posix-cpu-timers: Deduplicate rlimit handling posix-cpu-timers: Remove pointless comparisons posix-cpu-timers: Get rid of 64bit divisions posix-cpu-timers: Consolidate timer expiry further posix-cpu-timers: Get rid of zero checks rlimit: Rewrite non-sensical RLIMIT_CPU comment posix-cpu-timers: Respect INFINITY for hard RTTIME limit posix-cpu-timers: Switch thread group sampling to array posix-cpu-timers: Restructure expiry array posix-cpu-timers: Remove cputime_expires ...
2019-09-16Merge branch 'x86-cpu-for-linus' of ↵Linus Torvalds1-14/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cpu-feature updates from Ingo Molnar: - Rework the Intel model names symbols/macros, which were decades of ad-hoc extensions and added random noise. It's now a coherent, easy to follow nomenclature. - Add new Intel CPU model IDs: - "Tiger Lake" desktop and mobile models - "Elkhart Lake" model ID - and the "Lightning Mountain" variant of Airmont, plus support code - Add the new AVX512_VP2INTERSECT instruction to cpufeatures - Remove Intel MPX user-visible APIs and the self-tests, because the toolchain (gcc) is not supporting it going forward. This is the first, lowest-risk phase of MPX removal. - Remove X86_FEATURE_MFENCE_RDTSC - Various smaller cleanups and fixes * 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits) x86/cpu: Update init data for new Airmont CPU model x86/cpu: Add new Airmont variant to Intel family x86/cpu: Add Elkhart Lake to Intel family x86/cpu: Add Tiger Lake to Intel family x86: Correct misc typos x86/intel: Add common OPTDIFFs x86/intel: Aggregate microserver naming x86/intel: Aggregate big core graphics naming x86/intel: Aggregate big core mobile naming x86/intel: Aggregate big core client naming x86/cpufeature: Explain the macro duplication x86/ftrace: Remove mcount() declaration x86/PCI: Remove superfluous returns from void functions x86/msr-index: Move AMD MSRs where they belong x86/cpu: Use constant definitions for CPU models lib: Remove redundant ftrace flag removal x86/crash: Remove unnecessary comparison x86/bitops: Use __builtin_constant_p() directly instead of IS_IMMEDIATE() x86: Remove X86_FEATURE_MFENCE_RDTSC x86/mpx: Remove MPX APIs ...
2019-08-28posix-cpu-timers: Get rid of zero checksThomas Gleixner1-9/+0
Deactivation of the expiry cache is done by setting all clock caches to 0. That requires to have a check for zero in all places which update the expiry cache: if (cache == 0 || new < cache) cache = new; Use U64_MAX as the deactivated value, which allows to remove the zero checks when updating the cache and reduces it to the obvious check: if (new < cache) cache = new; This also removes the weird workaround in do_prlimit() which was required to convert a RLIMIT_CPU value of 0 (immediate expiry) to 1 because handing in 0 to the posix CPU timer code would have effectively disarmed it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192922.275086128@linutronix.de
2019-08-28rlimit: Rewrite non-sensical RLIMIT_CPU commentThomas Gleixner1-4/+3
The comment above the function which arms RLIMIT_CPU in the posix CPU timer code makes no sense at all. It claims that the kernel does not return an error code when it rejected the attempt to set RLIMIT_CPU. That's clearly bogus as the code does an error check and the rlimit is only set and activated when the permission checks are ok. In case of a rejection an appropriate error code is returned. This is a historical and outdated comment which got dragged along even when the rlimit handling code was rewritten. Replace it with an explanation why the setup function is not called when the rlimit value is RLIM_INFINITY and how the 'disarming' is handled. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192922.185511287@linutronix.de
2019-08-20arm64: Tighten the PR_{SET, GET}_TAGGED_ADDR_CTRL prctl() unused argumentsCatalin Marinas1-0/+4
Require that arg{3,4,5} of the PR_{SET,GET}_TAGGED_ADDR_CTRL prctl and arg2 of the PR_GET_TAGGED_ADDR_CTRL prctl() are zero rather than ignored for future extensions. Acked-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-06arm64: Introduce prctl() options to control the tagged user addresses ABICatalin Marinas1-0/+12
It is not desirable to relax the ABI to allow tagged user addresses into the kernel indiscriminately. This patch introduces a prctl() interface for enabling or disabling the tagged ABI with a global sysctl control for preventing applications from enabling the relaxed ABI (meant for testing user-space prctl() return error checking without reconfiguring the kernel). The ABI properties are inherited by threads of the same application and fork()'ed children but cleared on execve(). A Kconfig option allows the overall disabling of the relaxed ABI. The PR_SET_TAGGED_ADDR_CTRL will be expanded in the future to handle MTE-specific settings like imprecise vs precise exceptions. Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-07-22x86/mpx: Remove MPX APIsDave Hansen1-14/+2
MPX is being removed from the kernel due to a lack of support in the toolchain going forward (gcc). The first step is to remove the userspace-visible ABIs so that applications will stop using it. The most visible one are the enable/disable prctl()s. Remove them first. This is the most minimal and least invasive change needed to ensure that apps stop using MPX with new kernels. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20190705175321.DB42F0AD@viggo.jf.intel.com
2019-06-01prctl_set_mm: downgrade mmap_sem to read lockMichal Koutný1-2/+9
The commit a3b609ef9f8b ("proc read mm's {arg,env}_{start,end} with mmap semaphore taken.") added synchronization of reading argument/environment boundaries under mmap_sem. Later commit 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct") avoided the coarse use of mmap_sem in similar situations. But there still remained two places that (mis)use mmap_sem. get_cmdline should also use arg_lock instead of mmap_sem when it reads the boundaries. The second place that should use arg_lock is in prctl_set_mm. By protecting the boundaries fields with the arg_lock, we can downgrade mmap_sem to reader lock (analogous to what we already do in prctl_set_mm_map). [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/20190502125203.24014-3-mkoutny@suse.com Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct") Signed-off-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> Co-developed-by: Laurent Dufour <ldufour@linux.ibm.com> Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Mateusz Guzik <mguzik@redhat.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-06-01prctl_set_mm: refactor checks from validate_prctl_mapMichal Koutný1-26/+25
Despite comment of validate_prctl_map claims there are no capability checks, it is not completely true since commit 4d28df6152aa ("prctl: Allow local CAP_SYS_ADMIN changing exe_file"). Extract the check out of the function and make the function perform purely arithmetic checks. This patch should not change any behavior, it is mere refactoring for following patch. [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/20190502125203.24014-2-mkoutny@suse.com Signed-off-by: Michal Koutný <mkoutny@suse.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Mateusz Guzik <mguzik@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14kernel/sys.c: prctl: fix false positive in validate_prctl_map()Cyrill Gorcunov1-1/+1
While validating new map we require the @start_data to be strictly less than @end_data, which is fine for regular applications (this is why this nit didn't trigger for that long). These members are set from executable loaders such as elf handers, still it is pretty valid to have a loadable data section with zero size in file, in such case the start_data is equal to end_data once kernel loader finishes. As a result when we're trying to restore such programs the procedure fails and the kernel returns -EINVAL. From the image dump of a program: | "mm_start_code": "0x400000", | "mm_end_code": "0x8f5fb4", | "mm_start_data": "0xf1bfb0", | "mm_end_data": "0xf1bfb0", Thus we need to c