diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index f5154c051d2c1..6249dac617018 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3295,7 +3295,7 @@ static int uprobe_prog_run(struct bpf_uprobe *uprobe, struct bpf_run_ctx *old_run_ctx; int err = 0; - if (link->task && current != link->task) + if (link->task && current->mm != link->task->mm) return 0; if (sleepable) @@ -3396,8 +3396,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr upath = u64_to_user_ptr(attr->link_create.uprobe_multi.path); uoffsets = u64_to_user_ptr(attr->link_create.uprobe_multi.offsets); cnt = attr->link_create.uprobe_multi.cnt; + pid = attr->link_create.uprobe_multi.pid; - if (!upath || !uoffsets || !cnt) + if (!upath || !uoffsets || !cnt || pid < 0) return -EINVAL; if (cnt > MAX_UPROBE_MULTI_CNT) return -E2BIG; @@ -3421,11 +3422,8 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr goto error_path_put; } - pid = attr->link_create.uprobe_multi.pid; if (pid) { - rcu_read_lock(); - task = get_pid_task(find_vpid(pid), PIDTYPE_PID); - rcu_read_unlock(); + task = get_pid_task(find_vpid(pid), PIDTYPE_TGID); if (!task) { err = -ESRCH; goto error_path_put; diff --git a/tools/lib/bpf/features.c b/tools/lib/bpf/features.c index a336786a22a38..3df0125ed5fa7 100644 --- a/tools/lib/bpf/features.c +++ b/tools/lib/bpf/features.c @@ -392,11 +392,40 @@ static int probe_uprobe_multi_link(int token_fd) link_fd = bpf_link_create(prog_fd, -1, BPF_TRACE_UPROBE_MULTI, &link_opts); err = -errno; /* close() can clobber errno */ + if (link_fd >= 0 || err != -EBADF) { + close(link_fd); + close(prog_fd); + return 0; + } + + /* Initial multi-uprobe support in kernel didn't handle PID filtering + * correctly (it was doing thread filtering, not process filtering). + * So now we'll detect if PID filtering logic was fixed, and, if not, + * we'll pretend multi-uprobes are not supported, if not. + * Multi-uprobes are used in USDT attachment logic, and we need to be + * conservative here, because multi-uprobe selection happens early at + * load time, while the use of PID filtering is known late at + * attachment time, at which point it's too late to undo multi-uprobe + * selection. + * + * Creating uprobe with pid == -1 for (invalid) '/' binary will fail + * early with -EINVAL on kernels with fixed PID filtering logic; + * otherwise -ESRCH would be returned if passed correct binary path + * (but we'll just get -BADF, of course). + */ + link_opts.uprobe_multi.pid = -1; /* invalid PID */ + link_opts.uprobe_multi.path = "/"; /* invalid path */ + link_opts.uprobe_multi.offsets = &offset; + link_opts.uprobe_multi.cnt = 1; + + link_fd = bpf_link_create(prog_fd, -1, BPF_TRACE_UPROBE_MULTI, &link_opts); + err = -errno; /* close() can clobber errno */ + if (link_fd >= 0) close(link_fd); close(prog_fd); - return link_fd < 0 && err == -EBADF; + return link_fd < 0 && err == -EINVAL; } static int probe_kern_bpf_cookie(int token_fd) diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c index 8269cdee33ae9..bf6ca8e3eb131 100644 --- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c @@ -1,12 +1,14 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include #include #include "uprobe_multi.skel.h" #include "uprobe_multi_bench.skel.h" #include "uprobe_multi_usdt.skel.h" #include "bpf/libbpf_internal.h" #include "testing_helpers.h" +#include "../sdt.h" static char test_data[] = "test_data"; @@ -25,9 +27,17 @@ noinline void uprobe_multi_func_3(void) asm volatile (""); } +noinline void usdt_trigger(void) +{ + STAP_PROBE(test, pid_filter_usdt); +} + struct child { int go[2]; + int c2p[2]; /* child -> parent channel */ int pid; + int tid; + pthread_t thread; }; static void release_child(struct child *child) @@ -38,6 +48,10 @@ static void release_child(struct child *child) return; close(child->go[1]); close(child->go[0]); + if (child->thread) + pthread_join(child->thread, NULL); + close(child->c2p[0]); + close(child->c2p[1]); if (child->pid > 0) waitpid(child->pid, &child_status, 0); } @@ -63,7 +77,7 @@ static struct child *spawn_child(void) if (pipe(child.go)) return NULL; - child.pid = fork(); + child.pid = child.tid = fork(); if (child.pid < 0) { release_child(&child); errno = EINVAL; @@ -82,6 +96,7 @@ static struct child *spawn_child(void) uprobe_multi_func_1(); uprobe_multi_func_2(); uprobe_multi_func_3(); + usdt_trigger(); exit(errno); } @@ -89,6 +104,67 @@ static struct child *spawn_child(void) return &child; } +static void *child_thread(void *ctx) +{ + struct child *child = ctx; + int c = 0, err; + + child->tid = syscall(SYS_gettid); + + /* let parent know we are ready */ + err = write(child->c2p[1], &c, 1); + if (err != 1) + pthread_exit(&err); + + /* wait for parent's kick */ + err = read(child->go[0], &c, 1); + if (err != 1) + pthread_exit(&err); + + uprobe_multi_func_1(); + uprobe_multi_func_2(); + uprobe_multi_func_3(); + usdt_trigger(); + + err = 0; + pthread_exit(&err); +} + +static struct child *spawn_thread(void) +{ + static struct child child; + int c, err; + + /* pipe to notify child to execute the trigger functions */ + if (pipe(child.go)) + return NULL; + /* pipe to notify parent that child thread is ready */ + if (pipe(child.c2p)) { + close(child.go[0]); + close(child.go[1]); + return NULL; + } + + child.pid = getpid(); + + err = pthread_create(&child.thread, NULL, child_thread, &child); + if (err) { + err = -errno; + close(child.go[0]); + close(child.go[1]); + close(child.c2p[0]); + close(child.c2p[1]); + errno = -err; + return NULL; + } + + err = read(child.c2p[0], &c, 1); + if (!ASSERT_EQ(err, 1, "child_thread_ready")) + return NULL; + + return &child; +} + static void uprobe_multi_test_run(struct uprobe_multi *skel, struct child *child) { skel->bss->uprobe_multi_func_1_addr = (__u64) uprobe_multi_func_1; @@ -103,15 +179,23 @@ static void uprobe_multi_test_run(struct uprobe_multi *skel, struct child *child * passed at the probe attach. */ skel->bss->pid = child ? 0 : getpid(); + skel->bss->expect_pid = child ? child->pid : 0; + + /* trigger all probes, if we are testing child *process*, just to make + * sure that PID filtering doesn't let through activations from wrong + * PIDs; when we test child *thread*, we don't want to do this to + * avoid double counting number of triggering events + */ + if (!child || !child->thread) { + uprobe_multi_func_1(); + uprobe_multi_func_2(); + uprobe_multi_func_3(); + usdt_trigger(); + } if (child) kick_child(child); - /* trigger all probes */ - uprobe_multi_func_1(); - uprobe_multi_func_2(); - uprobe_multi_func_3(); - /* * There are 2 entry and 2 exit probe called for each uprobe_multi_func_[123] * function and each slepable probe (6) increments uprobe_multi_sleep_result. @@ -126,8 +210,12 @@ static void uprobe_multi_test_run(struct uprobe_multi *skel, struct child *child ASSERT_EQ(skel->bss->uprobe_multi_sleep_result, 6, "uprobe_multi_sleep_result"); - if (child) + ASSERT_FALSE(skel->bss->bad_pid_seen, "bad_pid_seen"); + + if (child) { ASSERT_EQ(skel->bss->child_pid, child->pid, "uprobe_multi_child_pid"); + ASSERT_EQ(skel->bss->child_tid, child->tid, "uprobe_multi_child_tid"); + } } static void test_skel_api(void) @@ -190,8 +278,24 @@ __test_attach_api(const char *binary, const char *pattern, struct bpf_uprobe_mul if (!ASSERT_OK_PTR(skel->links.uprobe_extra, "bpf_program__attach_uprobe_multi")) goto cleanup; + /* Attach (uprobe-backed) USDTs */ + skel->links.usdt_pid = bpf_program__attach_usdt(skel->progs.usdt_pid, pid, binary, + "test", "pid_filter_usdt", NULL); + if (!ASSERT_OK_PTR(skel->links.usdt_pid, "attach_usdt_pid")) + goto cleanup; + + skel->links.usdt_extra = bpf_program__attach_usdt(skel->progs.usdt_extra, -1, binary, + "test", "pid_filter_usdt", NULL); + if (!ASSERT_OK_PTR(skel->links.usdt_extra, "attach_usdt_extra")) + goto cleanup; + uprobe_multi_test_run(skel, child); + ASSERT_FALSE(skel->bss->bad_pid_seen_usdt, "bad_pid_seen_usdt"); + if (child) { + ASSERT_EQ(skel->bss->child_pid_usdt, child->pid, "usdt_multi_child_pid"); + ASSERT_EQ(skel->bss->child_tid_usdt, child->tid, "usdt_multi_child_tid"); + } cleanup: uprobe_multi__destroy(skel); } @@ -210,6 +314,13 @@ test_attach_api(const char *binary, const char *pattern, struct bpf_uprobe_multi return; __test_attach_api(binary, pattern, opts, child); + + /* pid filter (thread) */ + child = spawn_thread(); + if (!ASSERT_OK_PTR(child, "spawn_thread")) + return; + + __test_attach_api(binary, pattern, opts, child); } static void test_attach_api_pattern(void) @@ -397,7 +508,7 @@ static void test_attach_api_fails(void) link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts); if (!ASSERT_ERR(link_fd, "link_fd")) goto cleanup; - ASSERT_EQ(link_fd, -ESRCH, "pid_is_wrong"); + ASSERT_EQ(link_fd, -EINVAL, "pid_is_wrong"); cleanup: if (link_fd >= 0) @@ -495,6 +606,13 @@ static void test_link_api(void) return; __test_link_api(child); + + /* pid filter (thread) */ + child = spawn_thread(); + if (!ASSERT_OK_PTR(child, "spawn_thread")) + return; + + __test_link_api(child); } static void test_bench_attach_uprobe(void) diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi.c b/tools/testing/selftests/bpf/progs/uprobe_multi.c index 419d9aa28fce5..44190efcdba21 100644 --- a/tools/testing/selftests/bpf/progs/uprobe_multi.c +++ b/tools/testing/selftests/bpf/progs/uprobe_multi.c @@ -1,8 +1,8 @@ // SPDX-License-Identifier: GPL-2.0 -#include +#include "vmlinux.h" #include #include -#include +#include char _license[] SEC("license") = "GPL"; @@ -22,6 +22,13 @@ __u64 uprobe_multi_sleep_result = 0; int pid = 0; int child_pid = 0; +int child_tid = 0; +int child_pid_usdt = 0; +int child_tid_usdt = 0; + +int expect_pid = 0; +bool bad_pid_seen = false; +bool bad_pid_seen_usdt = false; bool test_cookie = false; void *user_ptr = 0; @@ -36,11 +43,19 @@ static __always_inline bool verify_sleepable_user_copy(void) static void uprobe_multi_check(void *ctx, bool is_return, bool is_sleep) { - child_pid = bpf_get_current_pid_tgid() >> 32; + __u64 cur_pid_tgid = bpf_get_current_pid_tgid(); + __u32 cur_pid; - if (pid && child_pid != pid) + cur_pid = cur_pid_tgid >> 32; + if (pid && cur_pid != pid) return; + if (expect_pid && cur_pid != expect_pid) + bad_pid_seen = true; + + child_pid = cur_pid_tgid >> 32; + child_tid = (__u32)cur_pid_tgid; + __u64 cookie = test_cookie ? bpf_get_attach_cookie(ctx) : 0; __u64 addr = bpf_get_func_ip(ctx); @@ -97,5 +112,32 @@ int uretprobe_sleep(struct pt_regs *ctx) SEC("uprobe.multi//proc/self/exe:uprobe_multi_func_*") int uprobe_extra(struct pt_regs *ctx) { + /* we need this one just to mix PID-filtered and global uprobes */ + return 0; +} + +SEC("usdt") +int usdt_pid(struct pt_regs *ctx) +{ + __u64 cur_pid_tgid = bpf_get_current_pid_tgid(); + __u32 cur_pid; + + cur_pid = cur_pid_tgid >> 32; + if (pid && cur_pid != pid) + return 0; + + if (expect_pid && cur_pid != expect_pid) + bad_pid_seen_usdt = true; + + child_pid_usdt = cur_pid_tgid >> 32; + child_tid_usdt = (__u32)cur_pid_tgid; + + return 0; +} + +SEC("usdt") +int usdt_extra(struct pt_regs *ctx) +{ + /* we need this one just to mix PID-filtered and global USDT probes */ return 0; }