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/cred.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 security/landlock/cred.c (limited to 'security/landlock/cred.c') diff --git a/security/landlock/cred.c b/security/landlock/cred.c new file mode 100644 index 000000000..cc419de75 --- /dev/null +++ b/security/landlock/cred.c @@ -0,0 +1,69 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock - Credential hooks + * + * Copyright © 2017-2020 Mickaël Salaün + * Copyright © 2018-2020 ANSSI + * Copyright © 2024-2025 Microsoft Corporation + */ + +#include +#include +#include + +#include "common.h" +#include "cred.h" +#include "ruleset.h" +#include "setup.h" + +static void hook_cred_transfer(struct cred *const new, + const struct cred *const old) +{ + const struct landlock_cred_security *const old_llcred = + landlock_cred(old); + + landlock_get_ruleset(old_llcred->domain); + *landlock_cred(new) = *old_llcred; +} + +static int hook_cred_prepare(struct cred *const new, + const struct cred *const old, const gfp_t gfp) +{ + hook_cred_transfer(new, old); + return 0; +} + +static void hook_cred_free(struct cred *const cred) +{ + struct landlock_ruleset *const dom = landlock_cred(cred)->domain; + + if (dom) + landlock_put_ruleset_deferred(dom); +} + +#ifdef CONFIG_AUDIT + +static int hook_bprm_creds_for_exec(struct linux_binprm *const bprm) +{ + /* Resets for each execution. */ + landlock_cred(bprm->cred)->domain_exec = 0; + return 0; +} + +#endif /* CONFIG_AUDIT */ + +static struct security_hook_list landlock_hooks[] __ro_after_init = { + LSM_HOOK_INIT(cred_prepare, hook_cred_prepare), + LSM_HOOK_INIT(cred_transfer, hook_cred_transfer), + LSM_HOOK_INIT(cred_free, hook_cred_free), + +#ifdef CONFIG_AUDIT + LSM_HOOK_INIT(bprm_creds_for_exec, hook_bprm_creds_for_exec), +#endif /* CONFIG_AUDIT */ +}; + +__init void landlock_add_cred_hooks(void) +{ + security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), + &landlock_lsmid); +} -- cgit v1.3.1