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2017-05-08ipc/shm: some shmat cleanupsDavidlohr Bueso1-9/+7
Clean up early flag and address some minutia. Link: http://lkml.kernel.org/r/1486673582-6979-3-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-03-02Merge branch 'for-linus' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs pile two from Al Viro: - orangefs fix - series of fs/namei.c cleanups from me - VFS stuff coming from overlayfs tree * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: orangefs: Use RCU for destroy_inode vfs: use helper for calling f_op->fsync() mm: use helper for calling f_op->mmap() vfs: use helpers for calling f_op->{read,write}_iter() vfs: pass type instead of fn to do_{loop,iter}_readv_writev() vfs: extract common parts of {compat_,}do_readv_writev() vfs: wrap write f_ops with file_{start,end}_write() vfs: deny copy_file_range() for non regular files vfs: deny fallocate() on directory vfs: create vfs helper vfs_tmpfile() namei.c: split unlazy_walk() namei.c: fold the check for DCACHE_OP_REVALIDATE into d_revalidate() lookup_fast(): clean up the logics around the fallback to non-rcu mode namei: fold unlazy_link() into its sole caller
2017-02-27ipc/shm: Fix shmat mmap nil-page protectionDavidlohr Bueso1-4/+9
The issue is described here, with a nice testcase: https://bugzilla.kernel.org/show_bug.cgi?id=192931 The problem is that shmat() calls do_mmap_pgoff() with MAP_FIXED, and the address rounded down to 0. For the regular mmap case, the protection mentioned above is that the kernel gets to generate the address -- arch_get_unmapped_area() will always check for MAP_FIXED and return that address. So by the time we do security_mmap_addr(0) things get funky for shmat(). The testcase itself shows that while a regular user crashes, root will not have a problem attaching a nil-page. There are two possible fixes to this. The first, and which this patch does, is to simply allow root to crash as well -- this is also regular mmap behavior, ie when hacking up the testcase and adding mmap(... |MAP_FIXED). While this approach is the safer option, the second alternative is to ignore SHM_RND if the rounded address is 0, thus only having MAP_SHARED flags. This makes the behavior of shmat() identical to the mmap() case. The downside of this is obviously user visible, but does make sense in that it maintains semantics after the round-down wrt 0 address and mmap. Passes shm related ltp tests. Link: http://lkml.kernel.org/r/1486050195-18629-1-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reported-by: Gareth Evans <gareth.evans@contextis.co.uk> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24userfaultfd: non-cooperative: add event for memory unmapsMike Rapoport1-4/+4
When a non-cooperative userfaultfd monitor copies pages in the background, it may encounter regions that were already unmapped. Addition of UFFD_EVENT_UNMAP allows the uffd monitor to track precisely changes in the virtual memory layout. Since there might be different uffd contexts for the affected VMAs, we first should create a temporary representation for the unmap event for each uffd context and then notify them one by one to the appropriate userfault file descriptors. The event notification occurs after the mmap_sem has been released. [arnd@arndb.de: fix nommu build] Link: http://lkml.kernel.org/r/20170203165141.3665284-1-arnd@arndb.de [mhocko@suse.com: fix nommu build] Link: http://lkml.kernel.org/r/20170202091503.GA22823@dhcp22.suse.cz Link: http://lkml.kernel.org/r/1485542673-24387-3-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Pavel Emelyanov <xemul@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24mm, fs: reduce fault, page_mkwrite, and pfn_mkwrite to take only vmfDave Jiang1-3/+3
->fault(), ->page_mkwrite(), and ->pfn_mkwrite() calls do not need to take a vma and vmf parameter when the vma already resides in vmf. Remove the vma parameter to simplify things. [arnd@arndb.de: fix ARM build] Link: http://lkml.kernel.org/r/20170125223558.1451224-1-arnd@arndb.de Link: http://lkml.kernel.org/r/148521301778.19116.10840599906674778980.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Jan Kara <jack@suse.com> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-20vfs: use helper for calling f_op->fsync()Miklos Szeredi1-1/+1
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-02-20mm: use helper for calling f_op->mmap()Miklos Szeredi1-1/+1
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-14ipc/shm.c: coding style fixesShailesh Pandey1-3/+10
This patch fixes below warnings: WARNING: Missing a blank line after declarations WARNING: Block comments use a trailing */ on a separate line ERROR: spaces required around that '=' (ctx:WxV) Above warnings were reported by checkpatch.pl Link: http://lkml.kernel.org/r/1478604980-18062-1-git-send-email-p.shailesh@samsung.com Signed-off-by: Shailesh Pandey <p.shailesh@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26shmem: make shmem_inode_info::lock irq-safeKirill A. Shutemov1-2/+2
We are going to need to call shmem_charge() under tree_lock to get accoutning right on collapse of small tmpfs pages into a huge one. The problem is that tree_lock is irq-safe and lockdep is not happy, that we take irq-unsafe lock under irq-safe[1]. Let's convert the lock to irq-safe. [1] https://gist.github.com/kiryl/80c0149e03ed35dfaf26628b8e03cdbc Link: http://lkml.kernel.org/r/1466021202-61880-34-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26shmem: get_unmapped_area align huge pageHugh Dickins1-2/+4
Provide a shmem_get_unmapped_area method in file_operations, called at mmap time to decide the mapping address. It could be conditional on CONFIG_TRANSPARENT_HUGEPAGE, but save #ifdefs in other places by making it unconditional. shmem_get_unmapped_area() first calls the usual mm->get_unmapped_area (which we treat as a black box, highly dependent on architecture and config and executable layout). Lots of conditions, and in most cases it just goes with the address that chose; but when our huge stars are rightly aligned, yet that did not provide a suitable address, go back to ask for a larger arena, within which to align the mapping suitably. There have to be some direct calls to shmem_get_unmapped_area(), not via the file_operations: because of the way shmem_zero_setup() is called to create a shmem object late in the mmap sequence, when MAP_SHARED is requested with MAP_ANONYMOUS or /dev/zero. Though this only matters when /proc/sys/vm/shmem_huge has been set. Link: http://lkml.kernel.org/r/1466021202-61880-29-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-23ipc, shm: make shmem attach/detach wait for mmap_sem killableMichal Hocko1-2/+7
shmat and shmdt rely on mmap_sem for write. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-02-18ipc/shm: handle removed segments gracefully in shm_mmap()Kirill A. Shutemov1-10/+43
remap_file_pages(2) emulation can reach file which represents removed IPC ID as long as a memory segment is mapped. It breaks expectations of IPC subsystem. Test case (rewritten to be more human readable, originally autogenerated by syzkaller[1]): #define _GNU_SOURCE #include <stdlib.h> #include <sys/ipc.h> #include <sys/mman.h> #include <sys/shm.h> #define PAGE_SIZE 4096 int main() { int id; void *p; id = shmget(IPC_PRIVATE, 3 * PAGE_SIZE, 0); p = shmat(id, NULL, 0); shmctl(id, IPC_RMID, NULL); remap_file_pages(p, 3 * PAGE_SIZE, 0, 7, 0); return 0; } The patch changes shm_mmap() and code around shm_lock() to propagate locking error back to caller of shm_mmap(). [1] http://github.com/google/syzkaller Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20ipc/shm.c: is_file_shm_hugepages() can be booleanYaowei Bai1-1/+1
Make is_file_shm_hugepages() return bool to improve readability due to this particular function only using either one or zero as its return value. No functional change. Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-30Initialize msg/shm IPC objects before doing ipc_addid()Linus Torvalds1-6/+7
As reported by Dmitry Vyukov, we really shouldn't do ipc_addid() before having initialized the IPC object state. Yes, we initialize the IPC object in a locked state, but with all the lockless RCU lookup work, that IPC object lock no longer means that the state cannot be seen. We already did this for the IPC semaphore code (see commit e8577d1f0329: "ipc/sem.c: fully initialize sem_array before making it visible") but we clearly forgot about msg and shm. Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-10ipc: convert invalid scenarios to use WARN_ONDavidlohr Bueso1-2/+2
Considering Linus' past rants about the (ab)use of BUG in the kernel, I took a look at how we deal with such calls in ipc. Given that any errors or corruption in ipc code are most likely contained within the set of processes participating in the broken mechanisms, there aren't really many strong fatal system failure scenarios that would require a BUG call. Also, if something is seriously wrong, ipc might not be the place for such a BUG either. 1. For example, recently, a customer hit one of these BUG_ONs in shm after failing shm_lock(). A busted ID imho does not merit a BUG_ON, and WARN would have been better. 2. MSG_COPY functionality of posix msgrcv(2) for checkpoint/restore. I don't see how we can hit this anyway -- at least it should be IS_ERR. The 'copy' arg from do_msgrcv is always set by calling prepare_copy() first and foremost. We could also probably drop this check altogether. Either way, it does not merit a BUG_ON. 3. No ->fault() callback for the fs getting the corresponding page -- seems selfish to make the system unusable. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-08-07ipc: use private shmem or hugetlbfs inodes for shm segments.Stephen Smalley1-1/+1
The shm implementation internally uses shmem or hugetlbfs inodes for shm segments. As these inodes are never directly exposed to userspace and only accessed through the shm operations which are already hooked by security modules, mark the inodes with the S_PRIVATE flag so that inode security initialization and permission checking is skipped. This was motivated by the following lockdep warning: ====================================================== [ INFO: possible circular locking dependency detected ] 4.2.0-0.rc3.git0.1.fc24.x86_64+debug #1 Tainted: G W ------------------------------------------------------- httpd/1597 is trying to acquire lock: (&ids->rwsem){+++++.}, at: shm_close+0x34/0x130 but task is already holding lock: (&mm->mmap_sem){++++++}, at: SyS_shmdt+0x4b/0x180 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&mm->mmap_sem){++++++}: lock_acquire+0xc7/0x270 __might_fault+0x7a/0xa0 filldir+0x9e/0x130 xfs_dir2_block_getdents.isra.12+0x198/0x1c0 [xfs] xfs_readdir+0x1b4/0x330 [xfs] xfs_file_readdir+0x2b/0x30 [xfs] iterate_dir+0x97/0x130 SyS_getdents+0x91/0x120 entry_SYSCALL_64_fastpath+0x12/0x76 -> #2 (&xfs_dir_ilock_class){++++.+}: lock_acquire+0xc7/0x270 down_read_nested+0x57/0xa0 xfs_ilock+0x167/0x350 [xfs] xfs_ilock_attr_map_shared+0x38/0x50 [xfs] xfs_attr_get+0xbd/0x190 [xfs] xfs_xattr_get+0x3d/0x70 [xfs] generic_getxattr+0x4f/0x70 inode_doinit_with_dentry+0x162/0x670 sb_finish_set_opts+0xd9/0x230 selinux_set_mnt_opts+0x35c/0x660 superblock_doinit+0x77/0xf0 delayed_superblock_init+0x10/0x20 iterate_supers+0xb3/0x110 selinux_complete_init+0x2f/0x40 security_load_policy+0x103/0x600 sel_write_load+0xc1/0x750 __vfs_write+0x37/0x100 vfs_write+0xa9/0x1a0 SyS_write+0x58/0xd0 entry_SYSCALL_64_fastpath+0x12/0x76 ... Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Reported-by: Morten Stevens <mstevens@fedoraproject.org> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Paul Moore <paul@paul-moore.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Eric Paris <eparis@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-30ipc: rename ipc_obtain_objectDavidlohr Bueso1-1/+1
... to ipc_obtain_object_idr, which is more meaningful and makes the code slightly easier to follow. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-30ipc,shm: move BUG_ON check into shm_lockDavidlohr Bueso1-5/+5
Upon every shm_lock call, we BUG_ON if an error was returned, indicating racing either in idr or in shm_destroy. Move this logic into the locking. [akpm@linux-foundation.org: simplify code] Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-26Merge branch 'for-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull fourth vfs update from Al Viro: "d_inode() annotations from David Howells (sat in for-next since before the beginning of merge window) + four assorted fixes" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: RCU pathwalk breakage when running into a symlink overmounting something fix I_DIO_WAKEUP definition direct-io: only inc/dec inode->i_dio_count for file systems fs/9p: fix readdir() VFS: assorted d_backing_inode() annotations VFS: fs/inode.c helpers: d_inode() annotations VFS: fs/cachefiles: d_backing_inode() annotations VFS: fs library helpers: d_inode() annotations VFS: assorted weird filesystems: d_inode() annotations VFS: normal filesystems (and lustre): d_inode() annotations VFS: security/: d_inode() annotations VFS: security/: d_backing_inode() annotations VFS: net/: d_inode() annotations VFS: net/unix: d_backing_inode() annotations VFS: kernel/: d_inode() annotations VFS: audit: d_backing_inode() annotations VFS: Fix up some ->d_inode accesses in the chelsio driver VFS: Cachefiles should perform fs modifications on the top layer only VFS: AF_UNIX sockets should call mknod on the top layer only
2015-04-15ipc: remove use of seq_printf return valueJoe Perches1-20/+22
The seq_printf return value, because it's frequently misused, will eventually be converted to void. See: commit 1f33c41c03da ("seq_file: Rename seq_overflow() to seq_has_overflowed() and make public") Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-15VFS: assorted weird filesystems: d_inode() annotationsDavid Howells1-1/+1
Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-13shmdt: use i_size_read() instead of ->i_sizeDave Hansen1-2/+3
Andrew Morton noted http://lkml.kernel.org/r/20141104142027.a7a0d010772d84560b445f59@linux-foundation.org that the shmdt uses inode->i_size outside of i_mutex being held. There is one more case in shm.c in shm_destroy(). This converts both users over to use i_size_read(). Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-13ipc/shm.c: fix overly aggressive shmdt() when calls span multiple segmentsDave Hansen1-5/+13
This is a highly-contrived scenario. But, a single shmdt() call can be induced in to unmapping memory from mulitple shm segments. Example code is here: http://www.sr71.net/~dave/intel/shmfun.c The fix is pretty simple: Record the 'struct file' for the first VMA we encounter and then stick to it. Decline to unmap anything not from the same file and thus the same segment. I found this by inspection and the odds of anyone hitting this in practice are pretty darn small. Lightly tested, but it's a pretty small patch. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Manfred Spraul <manfred@colorfullife.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-14ipc/shm: kill the historical/wrong mm->start_stack checkOleg Nesterov1-7/+0
do_shmat() is the only user of ->start_stack (proc just reports its value), and this check looks ugly and wrong. The reason for this check is not clear at all, and it wrongly assumes that the stack can only grow down. But the main problem is that in general mm->start_stack has nothing to do with stack_vma->vm_start. Not only the application can switch to another stack and even unmap this area, setup_arg_pages() expands the stack without updating mm->start_stack during exec(). This means that in the likely case "addr > start_stack - size - PAGE_SIZE * 5" is simply impossible after find_vma_intersection() == F, or the stack can't grow anyway because of RLIMIT_STACK. Many thanks to Hugh for his explanations. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-08shm: allow exit_shm in parallel if only marking orphansJack Miller1-32/+35
If shm_rmid_force (the default state) is not set then the shmids are only marked as orphaned and does not require any add, delete, or locking of the tree structure. Seperate the sysctl on and off case, and only obtain the read lock. The newly added list head can be deleted under the read lock because we are only called with current and will only change the semids allocated by this task and not manipulate the list. This commit assumes that up_read includes a sufficient memory barrier for the writes to be seen my others that later obtain a write lock. Signed-off-by: Milton Miller <miltonm@bga.com> Signed-off-by: Jack Miller <millerjo@us.ibm.com> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Anton Blanchard <anton@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-08shm: make exit_shm work proportional to task activityJack Miller1-11/+11
This is small set of patches our team has had kicking around for a few versions internally that fixes tasks getting hung on shm_exit when there are many threads hammering it at once. Anton wrote a simple test to cause the issue: http://ozlabs.org/~anton/junkcode/bust_shm_exit.c Before applying this patchset, this test code will cause either hanging tracebacks or pthread out of memory errors. After this patchset, it will still produce output like: root@somehost:~# ./bust_shm_exit 1024 160 ... INFO: rcu_sched detected stalls on CPUs/tasks: {} (detected by 116, t=2111 jiffies, g=241, c=240, q=7113) INFO: Stall ended before state dump start ... But the task will continue to run along happily, so we consider this an improvement over hanging, even if it's a bit noisy. This patch (of 3): exit_shm obtains the ipc_ns shm rwsem for write and holds it while it walks every shared memory segment in the namespace. Thus the amount of work is related to the number of shm segments in the namespace not the number of segments that might need to be cleaned. In addition, this occurs after the task has been notified the thread has exited, so the number of tasks waiting for the ns shm rwsem can grow without bound until memory is exausted. Add a list to the task struct of all shmids allocated by this task. Init the list head in copy_process. Use the ns->rwsem for locking. Add segments after id is added, remove before removing from id. On unshare of NEW_IPCNS orphan any ids as if the task had exited, similar to handling of semaphore undo. I chose a define for the init sequence since its a simple list init, otherwise it would require a function call to avoid include loops between the semaphore code and the task struct. Converting the list_del to list_del_init for the unshare cases would remove the exit followed by init, but I left it blow up if not inited. Signed-off-by: Milton Miller <miltonm@bga.com> Signed-off-by: Jack Miller <millerjo@us.ibm.com> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Anton Blanchard <anton@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06ipc/shm.c: check for integer overflow during shmget.Manfred Spraul1-0/+3
SHMMAX is the upper limit for the size of a shared memory segment, counted in bytes. The actual allocation is that size, rounded up to the next full page. Add a check that prevents the creation of segments where the rounded up size causes an integer overflow. Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Acked-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06ipc/shm.c: check for overflows of shm_totManfred Spraul1-1/+2
shm_tot counts the total number of pages used by shm segments. If SHMALL is ULONG_MAX (or nearly ULONG_MAX), then the number can overflow. Subsequent calls to shmctl(,SHM_INFO,) would return wrong values for shm_tot. The patch adds a detection for overflows. Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Acked-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06ipc/shm.c: check for ulong overflows in shmatManfred Spraul1-0/+3
The increase of SHMMAX/SHMALL is a 4 patch series. The change itself is trivial, the only problem are interger overflows. The overflows are not new, but if we make huge values the default, then the code should be free from overflows. SHMMAX: - shmmem_file_setup places a hard limit on the segment size: MAX_LFS_FILESIZE. On 32-bit, the limit is > 1 TB, i.e. 4 GB-1 byte segments are possible. Rounded up to full pages the actual allocated size is 0. --> must be fixed, patch 3 - shmat: - find_vma_intersection does not handle overflows properly. --> must be fixed, patch 1 - the rest is fine, do_mmap_pgoff limits mappings to TASK_SIZE and checks for overflows (i.e.: map 2 GB, starting from addr=2.5GB fails). SHMALL: - after creating 8192 segments size (1L<<63)-1, shm_tot overflows and returns 0. --> must be fixed, patch 2. Userspace: - Obviously, there could be overflows in userspace. There is nothing we can do, only use values smaller than ULONG_MAX. I ended with "ULONG_MAX - 1L<<24": - TASK_SIZE cannot be used because it is the size of the current task. Could be 4G if it's a 32-bit task on a 64-bit kernel. - The maximum size is not standardized across archs: I found TASK_MAX_SIZE, TASK_SIZE_MAX and TASK_SIZE_64. - Just in case some arch revives a 4G/4G split, nearly ULONG_MAX is a valid segment size. - Using "0" as a magic value for infinity is even worse, because right now 0 means 0, i.e. fail all allocations. This patch (of 4): find_vma_intersection() does not work as intended if addr+size overflows. The patch adds a manual check before the call to find_vma_intersection. Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Acked-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06ipc, kernel: clear whitespacePaul McQuade1-1/+1
trailing whitespace Signed-off-by: Paul McQuade <paulmcquad@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06ipc, kernel: use Linux headersPaul McQuade1-1/+1
Use #include <linux/uaccess.h> instead of <asm/uaccess.h> Use #include <linux/types.h> instead of <asm/types.h> Signed-off-by: Paul McQuade <paulmcquad@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06ipc: constify ipc_opsMathias Krause1-5/+5
There is no need to recreate the very same ipc_ops structure on every kernel entry for msgget/semget/shmget. Just declare it static and be done with it. While at it, constify it as we don't modify the structure at runtime. Found in the PaX patch, written by the PaX Team. Signed-off-by: Mathias Krause <minipli@googlemail.com> Cc: PaX Team <pageexec@freemail.hu> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-27ipc: standardize code commentsDavidlohr Bueso1-1/+0
IPC commenting style is all over the place, *specially* in util.c. This patch orders things a bit. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-27ipc: whitespace cleanupManfred Spraul1-16/+16
The ipc code does not adhere the typical linux coding style. This patch fixes lots of simple whitespace errors. - mostly autogenerated by scripts/checkpatch.pl -f --fix \ --types=pointer_location,spacing,space_before_tab - one manual fixup (keep structure members tab-aligned) - removal of additional space_before_tab that were not found by --fix Tested with some of my msg and sem test apps. Andrew: Could you include it in -mm and move it towards Linus' tree? Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Suggested-by: Li Bin <huawei.libin@huawei.com> Cc: Joe Perches <joe@perches.com> Acked-by: Rafael Aquini <aquini@redhat.com> Cc: Davidlohr Bueso <davidlohr@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-27ipc: introduce ipc_valid_object() helper to sort out IPC_RMID racesRafael Aquini1-8/+8
After the locking semantics for the SysV IPC API got improved, a couple of IPC_RMID race windows were opened because we ended up dropping the 'kern_ipc_perm.deleted' check performed way down in ipc_lock(). The spotted races got sorted out by re-introducing the old test within the racy critical sections. This patch introduces ipc_valid_object() to consolidate the way we cope with IPC_RMID races by using the same abstraction across the API implementation. Signed-off-by: Rafael Aquini <aquini@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Greg Thelen <gthelen@google.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-21ipc,shm: correct error return value in shmctl (SHM_UNLOCK)Jesper Nilsson1-3/+6
Commit 2caacaa82a51 ("ipc,shm: shorten critical region for shmctl") restructured the ipc shm to shorten critical region, but introduced a path where the return value could be -EPERM, even if the operation actually was performed. Before the commit, the err return value was reset by the return value from security_shm_shmctl() after the if (!ns_capable(...)) statement. Now, we still exit the if statement with err set to -EPERM, and in the case of SHM_UNLOCK, it is not reset at all, and used as the return value from shmctl. To fix this, we only set err when errors occur, leaving the fallthrough case alone. Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Rik van Riel <riel@redhat.com> Cc: Michel Lespinasse <walken@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: <stable@vger.kernel.org> [3.12.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-21ipc,shm: fix shm_file deletion racesGreg Thelen1-5/+23
When IPC_RMID races with other shm operations there's potential for use-after-free of the shm object's associated file (shm_file). Here's the race before this patch: TASK 1 TASK 2 ------ ------ shm_rmid() ipc_lock_object() shmctl() shp = shm_obtain_object_check() shm_destroy() shum_unlock() fput(shp->shm_file) ipc_lock_object() shmem_lock(shp->shm_file) <OOPS> The oops is caused because shm_destroy() calls fput() after dropping the ipc_lock. fput() clears the file's f_inode, f_path.dentry, and f_path.mnt, which causes various NULL pointer references in task 2. I reliably see the oops in task 2 if with shmlock, shmu This patch fixes the races by: 1) set shm_file=NULL in shm_destroy() while holding ipc_object_lock(). 2) modify at risk operations to check shm_file while holding ipc_object_lock(). Example workloads, which each trigger oops... Workload 1: while true; do id=$(shmget 1 4096) shm_rmid $id & shmlock $id & wait done The oops stack shows accessing NULL f_inode due to racing fput: _raw_spin_lock shmem_lock SyS_shmctl Workload 2: while true; do id=$(shmget 1 4096) shmat $id 4096 & shm_rmid $id & wait done The oops stack is similar to workload 1 due to NULL f_inode: touch_atime shmem_mmap shm_mmap mmap_region do_mmap_pgoff do_shmat SyS_shmat Workload 3: while true; do id=$(shmget 1 4096) shmlock $id shm_rmid $id & shmunlock $id & wait done The oops stack shows second fput tripping on an NULL f_inode. The first fput() completed via from shm_destroy(), but a racing thread did a get_file() and queued this fput(): locks_remove_flock __fput ____fput task_work_run do_notify_resume int_signal Fixes: c2c737a0461e ("ipc,shm: shorten critical region for shmat") Fixes: 2caacaa82a51 ("ipc,shm: shorten critical region for shmctl") Signed-off-by: Greg Thelen <gthelen@google.com> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: <stable@vger.kernel.org> # 3.10.17+ 3.11.6+ Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-24ipc: fix race with LSMsDavidlohr Bueso1-5/+12
Currently, IPC mechanisms do security and auditing related checks under RCU. However, since security modules can free the security structure, for example, through selinux_[sem,msg_queue,shm]_free_security(), we can race if the structure is freed before other tasks are done with it, creating a use-after-free condition. Manfred illustrates this nicely, for instance with shared mem and selinux: -> do_shmat calls rcu_read_lock() -> do_shmat calls shm_object_check(). Checks that the object is still valid - but doesn't acquire any locks. Then it returns. -> do_shmat calls security_shm_shmat (e.g. selinux_shm_shmat) -> selinux_shm_shmat calls ipc_has_perm() -> ipc_has_perm accesses ipc_perms->security shm_close() -> shm_close acquires rw_mutex & shm_lock -> shm_close calls shm_destroy -> shm_destroy calls security_shm_free (e.g. selinux_shm_free_security) -> selinux_shm_free_security calls ipc_free_security(&shp->shm_perm) -> ipc_free_security calls kfree(ipc_perms->security) This patch delays the freeing of the security structures after all RCU readers are done. Furthermore it aligns the security life cycle with that of the rest of IPC - freeing them based on the reference counter. For situations where we need not free security, the current behavior is kept. Linus states: "... the old behavior was suspect for another reason too: having the security blob go away from under a user sounds like it could cause various other problems anyway, so I think the old code was at least _prone_ to bugs even if it didn't have catastrophic behavior." I have tested this patch with IPC testcases from LTP on both my quad-core laptop and on a 64 core NUMA server. In both cases selinux is enabled, and tests pass for both voluntary and forced preemption models. While the mentioned races are theoretical (at least no one as reported them), I wanted to make sure that this new logic doesn't break anything we weren't aware of. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11ipc, shm: drop shm_lock_checkDavidlohr Bueso1-11/+0
This function was replaced by a the lockless shm_obtain_object_check(), and no longer has any users. Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11ipc, shm: guard against non-existant vma in shmdt(2)Davidlohr Bueso1-2/+1
When !CONFIG_MMU there's a chance we can derefence a NULL pointer when the VM area isn't found - check the return value of find_vma(). Also, remove the redundant -EINVAL return: retval is set to the proper return code and *only* changed to 0, when we actually unmap the segments. Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11ipc: rename ids->rw_mutexDavidlohr Bueso1-28/+28
Since in some situations the lock can be shared for readers, we shouldn't be calling it a mutex, rename it to rwsem. Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11ipc,shm: shorten critical region for shmatDavidlohr Bueso1-4/+10
Similar to other system calls, acquire the kern_ipc_perm lock after doing the initial permission and security checks. [sasha.levin@oracle.com: dont leave do_shmat with rcu lock held] Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11ipc,shm: cleanup do_shmat pastaDavidlohr Bueso1-14/+12
Clean up some of the messy do_shmat() spaghetti code, getting rid of out_free and out_put_dentry labels. This makes shortening the critical region of this function in the next patch a little easier to do and read. Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11ipc,shm: shorten critical region for shmctlDavidlohr Bueso1-24/+25
With the *_INFO, *_STAT, IPC_RMID and IPC_SET commands already optimized, deal with the remaining SHM_LOCK and SHM_UNLOCK commands. Take the shm_perm lock after doing the initial auditing and security checks. The rest of the logic remains unchanged. Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11ipc,shm: make shmctl_nolock locklessDavidlohr Bueso1-7/+12
While the INFO cmd doesn't take the ipc lock, the STAT commands do acquire it unnecessarily. We can do the permissions and security checks only holding the rcu lock. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11ipc,shm: introduce shmctl_nolockDavidlohr Bueso1-18/+39
Similar to semctl and msgctl, when calling msgctl, the *_INFO and *_STAT commands can be performed without acquiring the ipc object. Add a shmctl_nolock() function and move the logic of *_INFO and *_STAT out of msgctl(). Since we are just moving functionality, this change still takes the lock and it will be properly lockless in the next patch. Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11ipc,shm: shorten critical region in shmctl_downDavidlohr Bueso1-4/+6
Instead of holding the ipc lock for the entire function, use the ipcctl_pre_down_nolock and only acquire the lock for specific commands: RMID and SET. Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11ipc,shm: introduce lockless functions to obtain the ipc objectDavidlohr Bueso1-0/+20
This is the third and final patchset that deals with reducing the amount of contention we impose on the ipc lock (kern_ipc_perm.lock). These changes mostly deal with shared memory, previous work has already been done for semaphores and message queues: http://lkml.org/lkml/2013/3/20/546 (sems) http://lkml.org/lkml/2013/5/15/584 (mqueues) With these patches applied, a custom shm microbenchmark stressing shmctl doing IPC_STAT with 4 threads a million times, reduces the execution time by 50%. A similar run, this time with IPC_SET, reduces the execution time from 3 mins and 35 secs to 27 seconds. Patches 1-8: replaces blindly taking the ipc lock for a smarter combination of rcu and ipc_obtain_object, only acquiring the spinlock when updating. Patch 9: renames the ids rw_mutex to rwsem, which is what it already was. Patch 10: is a trivial mqueue leftover cleanup Patch 11: adds a brief lock scheme description, requested by Andrew. This patch: Add shm_obtain_object() and shm_obtain_object_check(), which will allow us to get the ipc object without acquiring the lock. Just as with other forms of ipc, these functions are basically wrappers around ipc_obtain_object*(). Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09ipc: move locking out of ipcctl_pre_down_nolockDavidlohr Bueso1-6/+17
This function currently acquires both the rw_mutex and the rcu lock on successful lookups, leaving the callers to explicitly unlock them, creating another two level locking situation. Make the callers (including those that still use ipcctl_pre_down()) explicitly lock and unlock the rwsem and rcu lock. Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09ipc: close open coded spin lock callsDavidlohr Bueso1-2/+2
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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