diff options
| -rw-r--r-- | kernel/bpf/trampoline.c | 5 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 60 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/config | 3 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/livepatch_trampoline.c | 107 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/livepatch_trampoline.c | 30 |
5 files changed, 185 insertions, 20 deletions
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 5949095e51c3..f2cb0b097093 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -479,11 +479,6 @@ again: * BPF_TRAMP_F_SHARE_IPMODIFY is set, we can generate the * trampoline again, and retry register. */ - /* reset fops->func and fops->trampoline for re-register */ - tr->fops->func = NULL; - tr->fops->trampoline = 0; - - /* free im memory and reallocate later */ bpf_tramp_image_free(im); goto again; } diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 42bd2ba68a82..59cfacb8a5bb 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1971,7 +1971,8 @@ static void ftrace_hash_rec_enable_modify(struct ftrace_ops *ops) */ static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops, struct ftrace_hash *old_hash, - struct ftrace_hash *new_hash) + struct ftrace_hash *new_hash, + bool update_target) { struct ftrace_page *pg; struct dyn_ftrace *rec, *end = NULL; @@ -2006,10 +2007,13 @@ static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops, if (rec->flags & FTRACE_FL_DISABLED) continue; - /* We need to update only differences of filter_hash */ + /* + * Unless we are updating the target of a direct function, + * we only need to update differences of filter_hash + */ in_old = !!ftrace_lookup_ip(old_hash, rec->ip); in_new = !!ftrace_lookup_ip(new_hash, rec->ip); - if (in_old == in_new) + if (!update_target && (in_old == in_new)) continue; if (in_new) { @@ -2020,7 +2024,16 @@ static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops, if (is_ipmodify) goto rollback; - FTRACE_WARN_ON(rec->flags & FTRACE_FL_DIRECT); + /* + * If this is called by __modify_ftrace_direct() + * then it is only changing where the direct + * pointer is jumping to, and the record already + * points to a direct trampoline. If it isn't, + * then it is a bug to update ipmodify on a direct + * caller. + */ + FTRACE_WARN_ON(!update_target && + (rec->flags & FTRACE_FL_DIRECT)); /* * Another ops with IPMODIFY is already @@ -2076,7 +2089,7 @@ static int ftrace_hash_ipmodify_enable(struct ftrace_ops *ops) if (ftrace_hash_empty(hash)) hash = NULL; - return __ftrace_hash_update_ipmodify(ops, EMPTY_HASH, hash); + return __ftrace_hash_update_ipmodify(ops, EMPTY_HASH, hash, false); } /* Disabling always succeeds */ @@ -2087,7 +2100,7 @@ static void ftrace_hash_ipmodify_disable(struct ftrace_ops *ops) if (ftrace_hash_empty(hash)) hash = NULL; - __ftrace_hash_update_ipmodify(ops, hash, EMPTY_HASH); + __ftrace_hash_update_ipmodify(ops, hash, EMPTY_HASH, false); } static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops, @@ -2101,7 +2114,7 @@ static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops, if (ftrace_hash_empty(new_hash)) new_hash = NULL; - return __ftrace_hash_update_ipmodify(ops, old_hash, new_hash); + return __ftrace_hash_update_ipmodify(ops, old_hash, new_hash, false); } static void print_ip_ins(const char *fmt, const unsigned char *p) @@ -5953,6 +5966,17 @@ static void register_ftrace_direct_cb(struct rcu_head *rhp) free_ftrace_hash(fhp); } +static void reset_direct(struct ftrace_ops *ops, unsigned long addr) +{ + struct ftrace_hash *hash = ops->func_hash->filter_hash; + + remove_direct_functions_hash(hash, addr); + + /* cleanup for possible another register call */ + ops->func = NULL; + ops->trampoline = 0; +} + /** * register_ftrace_direct - Call a custom trampoline directly * for multiple functions registered in @ops @@ -6048,6 +6072,8 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) ops->direct_call = addr; err = register_ftrace_function_nolock(ops); + if (err) + reset_direct(ops, addr); out_unlock: mutex_unlock(&direct_mutex); @@ -6080,7 +6106,6 @@ EXPORT_SYMBOL_GPL(register_ftrace_direct); int unregister_ftrace_direct(struct ftrace_ops *ops, unsigned long addr, bool free_filters) { - struct ftrace_hash *hash = ops->func_hash->filter_hash; int err; if (check_direct_multi(ops)) @@ -6090,13 +6115,9 @@ int unregister_ftrace_direct(struct ftrace_ops *ops, unsigned long addr, mutex_lock(&direct_mutex); err = unregister_ftrace_function(ops); - remove_direct_functions_hash(hash, addr); + reset_direct(ops, addr); mutex_unlock(&direct_mutex); - /* cleanup for possible another register call */ - ops->func = NULL; - ops->trampoline = 0; - if (free_filters) ftrace_free_filter(ops); return err; @@ -6106,7 +6127,7 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_direct); static int __modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) { - struct ftrace_hash *hash; + struct ftrace_hash *hash = ops->func_hash->filter_hash; struct ftrace_func_entry *entry, *iter; static struct ftrace_ops tmp_ops = { .func = ftrace_stub, @@ -6127,12 +6148,20 @@ __modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) return err; /* + * Call __ftrace_hash_update_ipmodify() here, so that we can call + * ops->ops_func for the ops. This is needed because the above + * register_ftrace_function_nolock() worked on tmp_ops. + */ + err = __ftrace_hash_update_ipmodify(ops, hash, hash, true); + if (err) + goto out; + + /* * Now the ftrace_ops_list_func() is called to do the direct callers. * We can safely change the direct functions attached to each entry. */ mutex_lock(&ftrace_lock); - hash = ops->func_hash->filter_hash; size = 1 << hash->size_bits; for (i = 0; i < size; i++) { hlist_for_each_entry(iter, &hash->buckets[i], hlist) { @@ -6147,6 +6176,7 @@ __modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) mutex_unlock(&ftrace_lock); +out: /* Removing the tmp_ops will add the updated direct callers to the functions */ unregister_ftrace_function(&tmp_ops); diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config index 70b28c1e653e..f2a2fd236ca8 100644 --- a/tools/testing/selftests/bpf/config +++ b/tools/testing/selftests/bpf/config @@ -50,6 +50,7 @@ CONFIG_IPV6_SIT=y CONFIG_IPV6_TUNNEL=y CONFIG_KEYS=y CONFIG_LIRC=y +CONFIG_LIVEPATCH=y CONFIG_LWTUNNEL=y CONFIG_MODULE_SIG=y CONFIG_MODULE_SRCVERSION_ALL=y @@ -111,6 +112,8 @@ CONFIG_IP6_NF_FILTER=y CONFIG_NF_NAT=y CONFIG_PACKET=y CONFIG_RC_CORE=y +CONFIG_SAMPLES=y +CONFIG_SAMPLE_LIVEPATCH=m CONFIG_SECURITY=y CONFIG_SECURITYFS=y CONFIG_SYN_COOKIES=y diff --git a/tools/testing/selftests/bpf/prog_tests/livepatch_trampoline.c b/tools/testing/selftests/bpf/prog_tests/livepatch_trampoline.c new file mode 100644 index 000000000000..72aa5376c30e --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/livepatch_trampoline.c @@ -0,0 +1,107 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */ + +#include <test_progs.h> +#include "testing_helpers.h" +#include "livepatch_trampoline.skel.h" + +static int load_livepatch(void) +{ + char path[4096]; + + /* CI will set KBUILD_OUTPUT */ + snprintf(path, sizeof(path), "%s/samples/livepatch/livepatch-sample.ko", + getenv("KBUILD_OUTPUT") ? : "../../../.."); + + return load_module(path, env_verbosity > VERBOSE_NONE); +} + +static void unload_livepatch(void) +{ + /* Disable the livepatch before unloading the module */ + system("echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled"); + + unload_module("livepatch_sample", env_verbosity > VERBOSE_NONE); +} + +static void read_proc_cmdline(void) +{ + char buf[4096]; + int fd, ret; + + fd = open("/proc/cmdline", O_RDONLY); + if (!ASSERT_OK_FD(fd, "open /proc/cmdline")) + return; + + ret = read(fd, buf, sizeof(buf)); + if (!ASSERT_GT(ret, 0, "read /proc/cmdline")) + goto out; + + ASSERT_OK(strncmp(buf, "this has been live patched", 26), "strncmp"); + +out: + close(fd); +} + +static void __test_livepatch_trampoline(bool fexit_first) +{ + struct livepatch_trampoline *skel = NULL; + int err; + + skel = livepatch_trampoline__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open_and_load")) + goto out; + + skel->bss->my_pid = getpid(); + + if (!fexit_first) { + /* fentry program is loaded first by default */ + err = livepatch_trampoline__attach(skel); + if (!ASSERT_OK(err, "skel_attach")) + goto out; + } else { + /* Manually load fexit program first. */ + skel->links.fexit_cmdline = bpf_program__attach(skel->progs.fexit_cmdline); + if (!ASSERT_OK_PTR(skel->links.fexit_cmdline, "attach_fexit")) + goto out; + + skel->links.fentry_cmdline = bpf_program__attach(skel->progs.fentry_cmdline); + if (!ASSERT_OK_PTR(skel->links.fentry_cmdline, "attach_fentry")) + goto out; + } + + read_proc_cmdline(); + + ASSERT_EQ(skel->bss->fentry_hit, 1, "fentry_hit"); + ASSERT_EQ(skel->bss->fexit_hit, 1, "fexit_hit"); +out: + livepatch_trampoline__destroy(skel); +} + +void test_livepatch_trampoline(void) +{ + int retry_cnt = 0; + +retry: + if (load_livepatch()) { + if (retry_cnt) { + ASSERT_OK(1, "load_livepatch"); + goto out; + } + /* + * Something else (previous run of the same test?) loaded + * the KLP module. Unload the KLP module and retry. + */ + unload_livepatch(); + retry_cnt++; + goto retry; + } + + if (test__start_subtest("fentry_first")) + __test_livepatch_trampoline(false); + + if (test__start_subtest("fexit_first")) + __test_livepatch_trampoline(true); +out: + unload_livepatch(); +} diff --git a/tools/testing/selftests/bpf/progs/livepatch_trampoline.c b/tools/testing/selftests/bpf/progs/livepatch_trampoline.c new file mode 100644 index 000000000000..15579d5bcd91 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/livepatch_trampoline.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */ + +#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +int fentry_hit; +int fexit_hit; +int my_pid; + +SEC("fentry/cmdline_proc_show") +int BPF_PROG(fentry_cmdline) +{ + if (my_pid != (bpf_get_current_pid_tgid() >> 32)) + return 0; + + fentry_hit = 1; + return 0; +} + +SEC("fexit/cmdline_proc_show") +int BPF_PROG(fexit_cmdline) +{ + if (my_pid != (bpf_get_current_pid_tgid() >> 32)) + return 0; + + fexit_hit = 1; + return 0; +} |