From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- security/lsm_syscalls.c | 129 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 129 insertions(+) create mode 100644 security/lsm_syscalls.c (limited to 'security/lsm_syscalls.c') diff --git a/security/lsm_syscalls.c b/security/lsm_syscalls.c new file mode 100644 index 000000000..08a017669 --- /dev/null +++ b/security/lsm_syscalls.c @@ -0,0 +1,129 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * System calls implementing the Linux Security Module API. + * + * Copyright (C) 2022 Casey Schaufler + * Copyright (C) 2022 Intel Corporation + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "lsm.h" + +/** + * lsm_name_to_attr - map an LSM attribute name to its ID + * @name: name of the attribute + * + * Returns the LSM attribute value associated with @name, or 0 if + * there is no mapping. + */ +u64 lsm_name_to_attr(const char *name) +{ + if (!strcmp(name, "current")) + return LSM_ATTR_CURRENT; + if (!strcmp(name, "exec")) + return LSM_ATTR_EXEC; + if (!strcmp(name, "fscreate")) + return LSM_ATTR_FSCREATE; + if (!strcmp(name, "keycreate")) + return LSM_ATTR_KEYCREATE; + if (!strcmp(name, "prev")) + return LSM_ATTR_PREV; + if (!strcmp(name, "sockcreate")) + return LSM_ATTR_SOCKCREATE; + return LSM_ATTR_UNDEF; +} + +/** + * sys_lsm_set_self_attr - Set current task's security module attribute + * @attr: which attribute to set + * @ctx: the LSM contexts + * @size: size of @ctx + * @flags: reserved for future use + * + * Sets the calling task's LSM context. On success this function + * returns 0. If the attribute specified cannot be set a negative + * value indicating the reason for the error is returned. + */ +SYSCALL_DEFINE4(lsm_set_self_attr, unsigned int, attr, struct lsm_ctx __user *, + ctx, u32, size, u32, flags) +{ + int rc; + + rc = mutex_lock_interruptible(¤t->signal->cred_guard_mutex); + if (rc < 0) + return rc; + rc = security_setselfattr(attr, ctx, size, flags); + mutex_unlock(¤t->signal->cred_guard_mutex); + return rc; +} + +/** + * sys_lsm_get_self_attr - Return current task's security module attributes + * @attr: which attribute to return + * @ctx: the user-space destination for the information, or NULL + * @size: pointer to the size of space available to receive the data + * @flags: special handling options. LSM_FLAG_SINGLE indicates that only + * attributes associated with the LSM identified in the passed @ctx be + * reported. + * + * Returns the calling task's LSM contexts. On success this + * function returns the number of @ctx array elements. This value + * may be zero if there are no LSM contexts assigned. If @size is + * insufficient to contain the return data -E2BIG is returned and + * @size is set to the minimum required size. In all other cases + * a negative value indicating the error is returned. + */ +SYSCALL_DEFINE4(lsm_get_self_attr, unsigned int, attr, struct lsm_ctx __user *, + ctx, u32 __user *, size, u32, flags) +{ + return security_getselfattr(attr, ctx, size, flags); +} + +/** + * sys_lsm_list_modules - Return a list of the active security modules + * @ids: the LSM module ids + * @size: pointer to size of @ids, updated on return + * @flags: reserved for future use, must be zero + * + * Returns a list of the active LSM ids. On success this function + * returns the number of @ids array elements. This value may be zero + * if there are no LSMs active. If @size is insufficient to contain + * the return data -E2BIG is returned and @size is set to the minimum + * required size. In all other cases a negative value indicating the + * error is returned. + */ +SYSCALL_DEFINE3(lsm_list_modules, u64 __user *, ids, u32 __user *, size, + u32, flags) +{ + u32 total_size = lsm_active_cnt * sizeof(*ids); + u32 usize; + int i; + + if (flags) + return -EINVAL; + + if (get_user(usize, size)) + return -EFAULT; + + if (put_user(total_size, size) != 0) + return -EFAULT; + + if (usize < total_size) + return -E2BIG; + + for (i = 0; i < lsm_active_cnt; i++) + if (put_user(lsm_idlist[i]->id, ids++)) + return -EFAULT; + + return lsm_active_cnt; +} -- cgit v1.3.1