From: Daniel Borkmann <daniel@iogearbox.net> mainline inclusion from mainline-v7.3-rc1 commit 2b918fe2f11f4fefed34b815004afe4ee352edf1 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/10047 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Cover the two loads which used to lose the BPF_PROBE_MEM rewrite, both reached from an RCU read-side critical section. The purpose of this patch is to assert load success in order to make sure to not trigger verifier_bug_if() on bpf_may_fault_on_deref() due to forgotten rewrite of a probed pointer. # LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t rcu_read_lock [...] #332/1 rcu_read_lock/success:OK #332/2 rcu_read_lock/rcuptr_acquire:OK #332/3 rcu_read_lock/negative_tests_inproper_region:OK #332/4 rcu_read_lock/negative_tests_rcuptr_misuse:OK #332 rcu_read_lock:OK Summary: 1/4 PASSED, 0 SKIPPED, 0/0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20260817141015.878071-2-daniel@iogearbox.net Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Conflicts: tools/testing/selftests/bpf/progs/rcu_read_lock.c [ctx conflicts] Signed-off-by: Pu Lehui <pulehui@huawei.com> --- .../selftests/bpf/prog_tests/rcu_read_lock.c | 2 + .../selftests/bpf/progs/rcu_read_lock.c | 76 +++++++++++++++++++ 2 files changed, 78 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c b/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c index a1f7e7378a64..accd9d21dd01 100644 --- a/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c +++ b/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c @@ -33,6 +33,8 @@ static void test_success(void) bpf_program__set_autoload(skel->progs.rcu_read_lock_global_subprog, true); bpf_program__set_autoload(skel->progs.rcu_read_lock_subprog_lock, true); bpf_program__set_autoload(skel->progs.rcu_read_lock_subprog_unlock, true); + bpf_program__set_autoload(skel->progs.non_own_ref_untrusted_ld, true); + bpf_program__set_autoload(skel->progs.rcu_untrusted_union_ld, true); err = rcu_read_lock__load(skel); if (!ASSERT_OK(err, "skel_load")) goto out; diff --git a/tools/testing/selftests/bpf/progs/rcu_read_lock.c b/tools/testing/selftests/bpf/progs/rcu_read_lock.c index ab3a532b7dd6..884ad0b7b13f 100644 --- a/tools/testing/selftests/bpf/progs/rcu_read_lock.c +++ b/tools/testing/selftests/bpf/progs/rcu_read_lock.c @@ -439,3 +439,79 @@ int rcu_read_lock_global_subprog_unlock(void *ctx) ret += global_subprog_unlock(ret); return 0; } + +struct rcu_node_data { + long key; + struct bpf_rb_node node; +}; + +struct rcu_node_stash { + struct rcu_node_data __kptr *node; +}; + +/* + * Necessary so that LLVM emits BTF for rcu_node_data rather than just a + * fwd reference to it, same as in progs/local_kptr_stash.c. + */ +struct rcu_node_data *just_here_because_btf_bug; + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 1); + __type(key, int); + __type(value, struct rcu_node_stash); +} node_stash SEC(".maps"); + +long non_own_ref_key; + +SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") +int non_own_ref_untrusted_ld(void *ctx) +{ + struct rcu_node_stash *stash; + struct rcu_node_data *node; + int key = 0; + + stash = bpf_map_lookup_elem(&node_stash, &key); + if (!stash) + return 0; + bpf_rcu_read_lock(); + node = stash->node; + if (!node) { + bpf_rcu_read_unlock(); + return 0; + } + bpf_rcu_read_unlock(); + /* + * The unlock leaves node as PTR_TO_BTF_ID | MEM_ALLOC | PTR_UNTRUSTED + * | NON_OWN_REF, and the load below has to get the BPF_PROBE_MEM + * rewrite for it, otherwise a bad address panics the kernel. + */ + non_own_ref_key = node->key; + return 0; +} + +long rcu_untrusted_wq_flags; + +SEC("?tp_btf/tcp_probe") +int BPF_PROG(rcu_untrusted_union_ld, struct sock *sk) +{ + struct socket_wq *wq; + + /* + * sk_wq sits in a two member union, so btf_struct_walk() marks the + * pointer PTR_UNTRUSTED, and the __rcu tag on the member adds MEM_RCU + * on top of it. struct sock is not on the __safe_rcu_or_null allow + * list, hence the two stay combined and the load below has to get the + * BPF_PROBE_MEM rewrite for PTR_TO_BTF_ID | PTR_UNTRUSTED | MEM_RCU, + * otherwise a bad address panics the kernel. + * + * The __rcu tag only reaches BTF on a clang built kernel, that is, one + * with CONFIG_PAHOLE_HAS_BTF_TAG. On a gcc built kernel the walk yields + * a plain untrusted pointer, which is rewritten either way. + */ + wq = sk->sk_wq; + if (!wq) + return 0; + rcu_untrusted_wq_flags = wq->flags; + return 0; +} -- 2.34.1