kernel/linux.git/ipc, branch v6.1.168

ipc: don't audit capability check in ipc_permissions()

2026-03-04T12:19:42+00:00

[ Upstream commit 071588136007482d70fd2667b827036bc60b1f8f ] The IPC sysctls implement the ctl_table_root::permissions hook and they override the file access mode based on the CAP_CHECKPOINT_RESTORE capability, which is being checked regardless of whether any access is actually denied or not, so if an LSM denies the capability, an audit record may be logged even when access is in fact granted. It wouldn't be viable to restructure the sysctl permission logic to only check the capability when the access would be actually denied if it's not granted. Thus, do the same as in net_ctl_permissions() (net/sysctl_net.c) - switch from ns_capable() to ns_capable_noaudit(), so that the check never emits an audit record. Fixes: 0889f44e2810 ("ipc: Check permissions for checkpoint_restart sysctls at open time") Signed-off-by: Ondrej Mosnacek Acked-by: Alexey Gladkov Acked-by: Serge Hallyn Signed-off-by: Serge Hallyn Stable-dep-of: 8924336531e2 ("ipc: don't audit capability check in ipc_permissions()") Signed-off-by: Sasha Levin

ipc: fix to protect IPCS lookups using RCU

2025-06-27T10:07:30+00:00

commit d66adabe91803ef34a8b90613c81267b5ded1472 upstream. syzbot reported that it discovered a use-after-free vulnerability, [0] [0]: https://lore.kernel.org/all/67af13f8.050a0220.21dd3.0038.GAE@google.com/ idr_for_each() is protected by rwsem, but this is not enough. If it is not protected by RCU read-critical region, when idr_for_each() calls radix_tree_node_free() through call_rcu() to free the radix_tree_node structure, the node will be freed immediately, and when reading the next node in radix_tree_for_each_slot(), the already freed memory may be read. Therefore, we need to add code to make sure that idr_for_each() is protected within the RCU read-critical region when we call it in shm_destroy_orphaned(). Link: https://lkml.kernel.org/r/20250424143322.18830-1-aha310510@gmail.com Fixes: b34a6b1da371 ("ipc: introduce shm_rmid_forced sysctl") Signed-off-by: Jeongjun Park Reported-by: syzbot+a2b84e569d06ca3a949c@syzkaller.appspotmail.com Cc: Jeongjun Park Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Vasiliy Kulikov Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

ipc: fix memleak if msg_init_ns failed in create_ipc_ns

2024-12-14T18:54:06+00:00

commit bc8f5921cd69188627c08041276238de222ab466 upstream. Percpu memory allocation may failed during create_ipc_ns however this fail is not handled properly since ipc sysctls and mq sysctls is not released properly. Fix this by release these two resource when failure. Here is the kmemleak stack when percpu failed: unreferenced object 0xffff88819de2a600 (size 512): comm "shmem_2nstest", pid 120711, jiffies 4300542254 hex dump (first 32 bytes): 60 aa 9d 84 ff ff ff ff fc 18 48 b2 84 88 ff ff `.........H..... 04 00 00 00 a4 01 00 00 20 e4 56 81 ff ff ff ff ........ .V..... backtrace (crc be7cba35): [] __kmalloc_node_track_caller_noprof+0x333/0x420 [] kmemdup_noprof+0x26/0x50 [] setup_mq_sysctls+0x57/0x1d0 [] copy_ipcs+0x29c/0x3b0 [] create_new_namespaces+0x1d0/0x920 [] copy_namespaces+0x2e9/0x3e0 [] copy_process+0x29f3/0x7ff0 [] kernel_clone+0xc0/0x650 [] __do_sys_clone+0xa1/0xe0 [] do_syscall_64+0xbf/0x1c0 [] entry_SYSCALL_64_after_hwframe+0x4b/0x53 Link: https://lkml.kernel.org/r/20241023093129.3074301-1-mawupeng1@huawei.com Fixes: 72d1e611082e ("ipc/msg: mitigate the lock contention with percpu counter") Signed-off-by: Ma Wupeng Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table)

2024-08-11T10:35:51+00:00

[ Upstream commit 520713a93d550406dae14d49cdb8778d70cecdfd ] Remove the 'table' argument from set_ownership as it is never used. This change is a step towards putting "struct ctl_table" into .rodata and eventually having sysctl core only use "const struct ctl_table". The patch was created with the following coccinelle script: @@ identifier func, head, table, uid, gid; @@ void func( struct ctl_table_header *head, - struct ctl_table *table, kuid_t *uid, kgid_t *gid) { ... } No additional occurrences of 'set_ownership' were found after doing a tree-wide search. Reviewed-by: Joel Granados Signed-off-by: Thomas Weißschuh Signed-off-by: Joel Granados Stable-dep-of: 98ca62ba9e2b ("sysctl: always initialize i_uid/i_gid") Signed-off-by: Sasha Levin

sysctl: allow to change limits for posix messages queues

2024-08-11T10:35:51+00:00

[ Upstream commit f9436a5d0497f759330d07e1189565edd4456be8 ] All parameters of posix messages queues (queues_max/msg_max/msgsize_max) end up being limited by RLIMIT_MSGQUEUE. The code in mqueue_get_inode is where that limiting happens. The RLIMIT_MSGQUEUE is bound to the user namespace and is counted hierarchically. We can allow root in the user namespace to modify the posix messages queues parameters. Link: https://lkml.kernel.org/r/6ad67f23d1459a4f4339f74aa73bac0ecf3995e1.1705333426.git.legion@kernel.org Signed-off-by: Alexey Gladkov Signed-off-by: Eric W. Biederman Link: https://lkml.kernel.org/r/7eb21211c8622e91d226e63416b1b93c079f60ee.1663756794.git.legion@kernel.org Cc: Christian Brauner Cc: Davidlohr Bueso Cc: Joel Granados Cc: Kees Cook Cc: Luis Chamberlain Cc: Manfred Spraul Signed-off-by: Andrew Morton Stable-dep-of: 98ca62ba9e2b ("sysctl: always initialize i_uid/i_gid") Signed-off-by: Sasha Levin

sysctl: allow change system v ipc sysctls inside ipc namespace

2024-08-11T10:35:51+00:00

[ Upstream commit 50ec499b9a43e46200c9f7b7d723ab2e4af540b3 ] Patch series "Allow to change ipc/mq sysctls inside ipc namespace", v3. Right now ipc and mq limits count as per ipc namespace, but only real root can change them. By default, the current values of these limits are such that it can only be reduced. Since only root can change the values, it is impossible to reduce these limits in the rootless container. We can allow limit changes within ipc namespace because mq parameters are limited by RLIMIT_MSGQUEUE and ipc parameters are not limited to anything other than cgroups. This patch (of 3): Rootless containers are not allowed to modify kernel IPC parameters. All default limits are set to such high values that in fact there are no limits at all. All limits are not inherited and are initialized to default values when a new ipc_namespace is created. For new ipc_namespace: size_t ipc_ns.shm_ctlmax = SHMMAX; // (ULONG_MAX - (1UL << 24)) size_t ipc_ns.shm_ctlall = SHMALL; // (ULONG_MAX - (1UL << 24)) int ipc_ns.shm_ctlmni = IPCMNI; // (1 << 15) int ipc_ns.shm_rmid_forced = 0; unsigned int ipc_ns.msg_ctlmax = MSGMAX; // 8192 unsigned int ipc_ns.msg_ctlmni = MSGMNI; // 32000 unsigned int ipc_ns.msg_ctlmnb = MSGMNB; // 16384 The shm_tot (total amount of shared pages) has also ceased to be global, it is located in ipc_namespace and is not inherited from anywhere. In such conditions, it cannot be said that these limits limit anything. The real limiter for them is cgroups. If we allow rootless containers to change these parameters, then it can only be reduced. Link: https://lkml.kernel.org/r/cover.1705333426.git.legion@kernel.org Link: https://lkml.kernel.org/r/d2f4603305cbfed58a24755aa61d027314b73a45.1705333426.git.legion@kernel.org Signed-off-by: Alexey Gladkov Signed-off-by: Eric W. Biederman Link: https://lkml.kernel.org/r/e2d84d3ec0172cfff759e6065da84ce0cc2736f8.1663756794.git.legion@kernel.org Cc: Christian Brauner Cc: Joel Granados Cc: Kees Cook Cc: Luis Chamberlain Cc: Manfred Spraul Cc: Davidlohr Bueso Signed-off-by: Andrew Morton Stable-dep-of: 98ca62ba9e2b ("sysctl: always initialize i_uid/i_gid") Signed-off-by: Sasha Levin

ipc: fix memory leak in init_mqueue_fs()

2022-12-31T12:32:01+00:00

[ Upstream commit 12b677f2c697d61e5ddbcb6c1650050a39392f54 ] When setup_mq_sysctls() failed in init_mqueue_fs(), mqueue_inode_cachep is not released. In order to fix this issue, the release path is reordered. Link: https://lkml.kernel.org/r/20221209092929.1978875-1-shaozhengchao@huawei.com Fixes: dc55e35f9e81 ("ipc: Store mqueue sysctls in the ipc namespace") Signed-off-by: Zhengchao Shao Cc: Alexey Gladkov Cc: "Eric W. Biederman" Cc: Jingyu Wang Cc: Muchun Song Cc: Roman Gushchin Cc: Waiman Long Cc: Wei Yongjun Cc: YueHaibing Cc: Yu Zhe Cc: Manfred Spraul Cc: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

ipc/sem: Fix dangling sem_array access in semtimedop race

2022-12-05T18:54:44+00:00

When __do_semtimedop() goes to sleep because it has to wait for a semaphore value becoming zero or becoming bigger than some threshold, it links the on-stack sem_queue to the sem_array, then goes to sleep without holding a reference on the sem_array. When __do_semtimedop() comes back out of sleep, one of two things must happen: a) We prove that the on-stack sem_queue has been disconnected from the (possibly freed) sem_array, making it safe to return from the stack frame that the sem_queue exists in. b) We stabilize our reference to the sem_array, lock the sem_array, and detach the sem_queue from the sem_array ourselves. sem_array has RCU lifetime, so for case (b), the reference can be stabilized inside an RCU read-side critical section by locklessly checking whether the sem_queue is still connected to the sem_array. However, the current code does the lockless check on sem_queue before starting an RCU read-side critical section, so the result of the lockless check immediately becomes useless. Fix it by doing rcu_read_lock() before the lockless check. Now RCU ensures that if we observe the object being on our queue, the object can't be freed until rcu_read_unlock(). This bug is only hittable on kernel builds with full preemption support (either CONFIG_PREEMPT or PREEMPT_DYNAMIC with preempt=full). Fixes: 370b262c896e ("ipc/sem: avoid idr tree lookup for interrupted semop") Cc: stable@vger.kernel.org Signed-off-by: Jann Horn Signed-off-by: Linus Torvalds

ipc/shm: call underlying open/close vm_ops

2022-11-23T02:50:42+00:00

Shared memory segments can be created that are backed by hugetlb pages. When this happens, the vmas associated with any mappings (shmat) are marked VM_HUGETLB, yet the vm_ops for such mappings are provided by ipc/shm (shm_vm_ops). There is a mechanism to call the underlying hugetlb vm_ops, and this is done for most operations. However, it is not done for open and close. This was not an issue until the introduction of the hugetlb vma_lock. This lock structure is pointed to by vm_private_data and the open/close vm_ops help maintain this structure. The special hugetlb routine called at fork took care of structure updates at fork time. However, vma_splitting is not properly handled for ipc shared memory mappings backed by hugetlb pages. This can result in a "kernel NULL pointer dereference" BUG or use after free as two vmas point to the same lock structure. Update the shm open and close routines to always call the underlying open and close routines. Link: https://lkml.kernel.org/r/20221114210018.49346-1-mike.kravetz@oracle.com Fixes: 8d9bfb260814 ("hugetlb: add vma based lock for pmd sharing") Signed-off-by: Mike Kravetz Reported-by: Doug Nelson Reported-by: Cc: Alexander Mikhalitsyn Cc: "Eric W . Biederman" Cc: Manfred Spraul Cc: Matthew Wilcox Cc: Miaohe Lin Cc: Michal Hocko Signed-off-by: Andrew Morton

ipc/msg.c: fix percpu_counter use after free

2022-10-28T20:37:22+00:00

These percpu counters are referenced in free_ipcs->freeque, so destroy them later. Fixes: 72d1e611082e ("ipc/msg: mitigate the lock contention with percpu counter") Reported-by: syzbot+96e659d35b9d6b541152@syzkaller.appspotmail.com Tested-by: Mark Rutland Cc: Jiebin Sun Signed-off-by: Andrew Morton