From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- security/landlock/setup.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 security/landlock/setup.c (limited to 'security/landlock/setup.c') diff --git a/security/landlock/setup.c b/security/landlock/setup.c new file mode 100644 index 000000000..47dac1736 --- /dev/null +++ b/security/landlock/setup.c @@ -0,0 +1,81 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock LSM - Security framework setup + * + * Copyright © 2016-2020 Mickaël Salaün + * Copyright © 2018-2020 ANSSI + */ + +#include +#include +#include +#include + +#include "common.h" +#include "cred.h" +#include "errata.h" +#include "fs.h" +#include "id.h" +#include "net.h" +#include "setup.h" +#include "task.h" + +bool landlock_initialized __ro_after_init = false; + +const struct lsm_id landlock_lsmid = { + .name = LANDLOCK_NAME, + .id = LSM_ID_LANDLOCK, +}; + +struct lsm_blob_sizes landlock_blob_sizes __ro_after_init = { + .lbs_cred = sizeof(struct landlock_cred_security), + .lbs_file = sizeof(struct landlock_file_security), + .lbs_inode = sizeof(struct landlock_inode_security), + .lbs_superblock = sizeof(struct landlock_superblock_security), +}; + +int landlock_errata __ro_after_init; + +static void __init compute_errata(void) +{ + size_t i; + +#ifndef __has_include + /* + * This is a safeguard to make sure the compiler implements + * __has_include (see errata.h). + */ + WARN_ON_ONCE(1); + return; +#endif + + for (i = 0; landlock_errata_init[i].number; i++) { + const int prev_errata = landlock_errata; + + if (WARN_ON_ONCE(landlock_errata_init[i].abi > + landlock_abi_version)) + continue; + + landlock_errata |= BIT(landlock_errata_init[i].number - 1); + WARN_ON_ONCE(prev_errata == landlock_errata); + } +} + +static int __init landlock_init(void) +{ + compute_errata(); + landlock_add_cred_hooks(); + landlock_add_task_hooks(); + landlock_add_fs_hooks(); + landlock_add_net_hooks(); + landlock_init_id(); + landlock_initialized = true; + pr_info("Up and running.\n"); + return 0; +} + +DEFINE_LSM(LANDLOCK_NAME) = { + .id = &landlock_lsmid, + .init = landlock_init, + .blobs = &landlock_blob_sizes, +}; -- cgit v1.3.1