* [PATCH bpf-next v5 1/2] bpf: implement bpf_send_signal_task() kfunc
2024-10-16 8:41 [PATCH bpf-next v5 0/2] Implement mechanism to signal other threads Puranjay Mohan
@ 2024-10-16 8:41 ` Puranjay Mohan
2024-10-16 8:41 ` [PATCH bpf-next v5 2/2] selftests/bpf: Augment send_signal test with remote signaling Puranjay Mohan
2024-10-21 22:10 ` [PATCH bpf-next v5 0/2] Implement mechanism to signal other threads patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Puranjay Mohan @ 2024-10-16 8:41 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, Eduard Zingerman, Song Liu, Yonghong Song,
John Fastabend, KP Singh, bpf, linux-kernel, puranjay12
Implement bpf_send_signal_task kfunc that is similar to
bpf_send_signal_thread and bpf_send_signal helpers but can be used to
send signals to other threads and processes. It also supports sending a
cookie with the signal similar to sigqueue().
If the receiving process establishes a handler for the signal using the
SA_SIGINFO flag to sigaction(), then it can obtain this cookie via the
si_value field of the siginfo_t structure passed as the second argument
to the handler.
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
---
kernel/bpf/helpers.c | 1 +
kernel/trace/bpf_trace.c | 53 ++++++++++++++++++++++++++++++++++------
2 files changed, 46 insertions(+), 8 deletions(-)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 073e6f04f4d76..5c3fdb29c1b1f 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -3055,6 +3055,7 @@ BTF_ID_FLAGS(func, bpf_task_get_cgroup1, KF_ACQUIRE | KF_RCU | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_task_from_pid, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_task_from_vpid, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_throw)
+BTF_ID_FLAGS(func, bpf_send_signal_task, KF_TRUSTED_ARGS)
BTF_KFUNCS_END(generic_btf_ids)
static const struct btf_kfunc_id_set generic_kfunc_set = {
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index a582cd25ca876..e7370a3211260 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -802,6 +802,8 @@ struct send_signal_irq_work {
struct task_struct *task;
u32 sig;
enum pid_type type;
+ bool has_siginfo;
+ struct kernel_siginfo info;
};
static DEFINE_PER_CPU(struct send_signal_irq_work, send_signal_work);
@@ -809,27 +811,46 @@ static DEFINE_PER_CPU(struct send_signal_irq_work, send_signal_work);
static void do_bpf_send_signal(struct irq_work *entry)
{
struct send_signal_irq_work *work;
+ struct kernel_siginfo *siginfo;
work = container_of(entry, struct send_signal_irq_work, irq_work);
- group_send_sig_info(work->sig, SEND_SIG_PRIV, work->task, work->type);
+ siginfo = work->has_siginfo ? &work->info : SEND_SIG_PRIV;
+
+ group_send_sig_info(work->sig, siginfo, work->task, work->type);
put_task_struct(work->task);
}
-static int bpf_send_signal_common(u32 sig, enum pid_type type)
+static int bpf_send_signal_common(u32 sig, enum pid_type type, struct task_struct *task, u64 value)
{
struct send_signal_irq_work *work = NULL;
+ struct kernel_siginfo info;
+ struct kernel_siginfo *siginfo;
+
+ if (!task) {
+ task = current;
+ siginfo = SEND_SIG_PRIV;
+ } else {
+ clear_siginfo(&info);
+ info.si_signo = sig;
+ info.si_errno = 0;
+ info.si_code = SI_KERNEL;
+ info.si_pid = 0;
+ info.si_uid = 0;
+ info.si_value.sival_ptr = (void *)(unsigned long)value;
+ siginfo = &info;
+ }
/* Similar to bpf_probe_write_user, task needs to be
* in a sound condition and kernel memory access be
* permitted in order to send signal to the current
* task.
*/
- if (unlikely(current->flags & (PF_KTHREAD | PF_EXITING)))
+ if (unlikely(task->flags & (PF_KTHREAD | PF_EXITING)))
return -EPERM;
if (unlikely(!nmi_uaccess_okay()))
return -EPERM;
/* Task should not be pid=1 to avoid kernel panic. */
- if (unlikely(is_global_init(current)))
+ if (unlikely(is_global_init(task)))
return -EPERM;
if (irqs_disabled()) {
@@ -847,19 +868,22 @@ static int bpf_send_signal_common(u32 sig, enum pid_type type)
* to the irq_work. The current task may change when queued
* irq works get executed.
*/
- work->task = get_task_struct(current);
+ work->task = get_task_struct(task);
+ work->has_siginfo = siginfo == &info;
+ if (work->has_siginfo)
+ copy_siginfo(&work->info, &info);
work->sig = sig;
work->type = type;
irq_work_queue(&work->irq_work);
return 0;
}
- return group_send_sig_info(sig, SEND_SIG_PRIV, current, type);
+ return group_send_sig_info(sig, siginfo, task, type);
}
BPF_CALL_1(bpf_send_signal, u32, sig)
{
- return bpf_send_signal_common(sig, PIDTYPE_TGID);
+ return bpf_send_signal_common(sig, PIDTYPE_TGID, NULL, 0);
}
static const struct bpf_func_proto bpf_send_signal_proto = {
@@ -871,7 +895,7 @@ static const struct bpf_func_proto bpf_send_signal_proto = {
BPF_CALL_1(bpf_send_signal_thread, u32, sig)
{
- return bpf_send_signal_common(sig, PIDTYPE_PID);
+ return bpf_send_signal_common(sig, PIDTYPE_PID, NULL, 0);
}
static const struct bpf_func_proto bpf_send_signal_thread_proto = {
@@ -3484,3 +3508,16 @@ static int __init bpf_kprobe_multi_kfuncs_init(void)
}
late_initcall(bpf_kprobe_multi_kfuncs_init);
+
+__bpf_kfunc_start_defs();
+
+__bpf_kfunc int bpf_send_signal_task(struct task_struct *task, int sig, enum pid_type type,
+ u64 value)
+{
+ if (type != PIDTYPE_PID && type != PIDTYPE_TGID)
+ return -EINVAL;
+
+ return bpf_send_signal_common(sig, type, task, value);
+}
+
+__bpf_kfunc_end_defs();
--
2.40.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH bpf-next v5 2/2] selftests/bpf: Augment send_signal test with remote signaling
2024-10-16 8:41 [PATCH bpf-next v5 0/2] Implement mechanism to signal other threads Puranjay Mohan
2024-10-16 8:41 ` [PATCH bpf-next v5 1/2] bpf: implement bpf_send_signal_task() kfunc Puranjay Mohan
@ 2024-10-16 8:41 ` Puranjay Mohan
2024-10-21 22:10 ` [PATCH bpf-next v5 0/2] Implement mechanism to signal other threads patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Puranjay Mohan @ 2024-10-16 8:41 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, Eduard Zingerman, Song Liu, Yonghong Song,
John Fastabend, KP Singh, bpf, linux-kernel, puranjay12
Add testcases to test bpf_send_signal_task(). In these new test cases,
the main process triggers the BPF program and the forked process
receives the signals. The target process's signal handler receives a
cookie from the bpf program.
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
---
.../selftests/bpf/prog_tests/send_signal.c | 133 +++++++++++++-----
.../bpf/progs/test_send_signal_kern.c | 35 ++++-
2 files changed, 130 insertions(+), 38 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal.c b/tools/testing/selftests/bpf/prog_tests/send_signal.c
index 6cc69900b3106..1aed94ec14efb 100644
--- a/tools/testing/selftests/bpf/prog_tests/send_signal.c
+++ b/tools/testing/selftests/bpf/prog_tests/send_signal.c
@@ -8,17 +8,25 @@ static int sigusr1_received;
static void sigusr1_handler(int signum)
{
- sigusr1_received = 1;
+ sigusr1_received = 8;
+}
+
+static void sigusr1_siginfo_handler(int s, siginfo_t *i, void *v)
+{
+ sigusr1_received = (int)(long long)i->si_value.sival_ptr;
}
static void test_send_signal_common(struct perf_event_attr *attr,
- bool signal_thread)
+ bool signal_thread, bool remote)
{
struct test_send_signal_kern *skel;
+ struct sigaction sa;
int pipe_c2p[2], pipe_p2c[2];
int err = -1, pmu_fd = -1;
+ volatile int j = 0;
char buf[256];
pid_t pid;
+ int old_prio;
if (!ASSERT_OK(pipe(pipe_c2p), "pipe_c2p"))
return;
@@ -39,11 +47,14 @@ static void test_send_signal_common(struct perf_event_attr *attr,
}
if (pid == 0) {
- int old_prio;
- volatile int j = 0;
-
/* install signal handler and notify parent */
- ASSERT_NEQ(signal(SIGUSR1, sigusr1_handler), SIG_ERR, "signal");
+ if (remote) {
+ sa.sa_sigaction = sigusr1_siginfo_handler;
+ sa.sa_flags = SA_RESTART | SA_SIGINFO;
+ ASSERT_NEQ(sigaction(SIGUSR1, &sa, NULL), -1, "sigaction");
+ } else {
+ ASSERT_NEQ(signal(SIGUSR1, sigusr1_handler), SIG_ERR, "signal");
+ }
close(pipe_c2p[0]); /* close read */
close(pipe_p2c[1]); /* close write */
@@ -52,10 +63,12 @@ static void test_send_signal_common(struct perf_event_attr *attr,
* that if an interrupt happens, the underlying task
* is this process.
*/
- errno = 0;
- old_prio = getpriority(PRIO_PROCESS, 0);
- ASSERT_OK(errno, "getpriority");
- ASSERT_OK(setpriority(PRIO_PROCESS, 0, -20), "setpriority");
+ if (!remote) {
+ errno = 0;
+ old_prio = getpriority(PRIO_PROCESS, 0);
+ ASSERT_OK(errno, "getpriority");
+ ASSERT_OK(setpriority(PRIO_PROCESS, 0, -20), "setpriority");
+ }
/* notify parent signal handler is installed */
ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write");
@@ -66,20 +79,25 @@ static void test_send_signal_common(struct perf_event_attr *attr,
/* wait a little for signal handler */
for (int i = 0; i < 1000000000 && !sigusr1_received; i++) {
j /= i + j + 1;
- if (!attr)
- /* trigger the nanosleep tracepoint program. */
- usleep(1);
+ if (remote)
+ sleep(1);
+ else
+ if (!attr)
+ /* trigger the nanosleep tracepoint program. */
+ usleep(1);
}
- buf[0] = sigusr1_received ? '2' : '0';
- ASSERT_EQ(sigusr1_received, 1, "sigusr1_received");
+ buf[0] = sigusr1_received;
+
+ ASSERT_EQ(sigusr1_received, 8, "sigusr1_received");
ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write");
/* wait for parent notification and exit */
ASSERT_EQ(read(pipe_p2c[0], buf, 1), 1, "pipe_read");
/* restore the old priority */
- ASSERT_OK(setpriority(PRIO_PROCESS, 0, old_prio), "setpriority");
+ if (!remote)
+ ASSERT_OK(setpriority(PRIO_PROCESS, 0, old_prio), "setpriority");
close(pipe_c2p[1]);
close(pipe_p2c[0]);
@@ -93,6 +111,17 @@ static void test_send_signal_common(struct perf_event_attr *attr,
if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
goto skel_open_load_failure;
+ /* boost with a high priority so we got a higher chance
+ * that if an interrupt happens, the underlying task
+ * is this process.
+ */
+ if (remote) {
+ errno = 0;
+ old_prio = getpriority(PRIO_PROCESS, 0);
+ ASSERT_OK(errno, "getpriority");
+ ASSERT_OK(setpriority(PRIO_PROCESS, 0, -20), "setpriority");
+ }
+
if (!attr) {
err = test_send_signal_kern__attach(skel);
if (!ASSERT_OK(err, "skel_attach")) {
@@ -100,8 +129,12 @@ static void test_send_signal_common(struct perf_event_attr *attr,
goto destroy_skel;
}
} else {
- pmu_fd = syscall(__NR_perf_event_open, attr, pid, -1 /* cpu */,
- -1 /* group id */, 0 /* flags */);
+ if (!remote)
+ pmu_fd = syscall(__NR_perf_event_open, attr, pid, -1 /* cpu */,
+ -1 /* group id */, 0 /* flags */);
+ else
+ pmu_fd = syscall(__NR_perf_event_open, attr, getpid(), -1 /* cpu */,
+ -1 /* group id */, 0 /* flags */);
if (!ASSERT_GE(pmu_fd, 0, "perf_event_open")) {
err = -1;
goto destroy_skel;
@@ -119,11 +152,30 @@ static void test_send_signal_common(struct perf_event_attr *attr,
/* trigger the bpf send_signal */
skel->bss->signal_thread = signal_thread;
skel->bss->sig = SIGUSR1;
- skel->bss->pid = pid;
+ if (!remote) {
+ skel->bss->target_pid = 0;
+ skel->bss->pid = pid;
+ } else {
+ skel->bss->target_pid = pid;
+ skel->bss->pid = getpid();
+ }
/* notify child that bpf program can send_signal now */
ASSERT_EQ(write(pipe_p2c[1], buf, 1), 1, "pipe_write");
+ /* For the remote test, the BPF program is triggered from this
+ * process but the other process/thread is signaled.
+ */
+ if (remote) {
+ if (!attr) {
+ for (int i = 0; i < 10; i++)
+ usleep(1);
+ } else {
+ for (int i = 0; i < 100000000; i++)
+ j /= i + 1;
+ }
+ }
+
/* wait for result */
err = read(pipe_c2p[0], buf, 1);
if (!ASSERT_GE(err, 0, "reading pipe"))
@@ -133,7 +185,7 @@ static void test_send_signal_common(struct perf_event_attr *attr,
goto disable_pmu;
}
- ASSERT_EQ(buf[0], '2', "incorrect result");
+ ASSERT_EQ(buf[0], 8, "incorrect result");
/* notify child safe to exit */
ASSERT_EQ(write(pipe_p2c[1], buf, 1), 1, "pipe_write");
@@ -142,18 +194,21 @@ static void test_send_signal_common(struct perf_event_attr *attr,
close(pmu_fd);
destroy_skel:
test_send_signal_kern__destroy(skel);
+ /* restore the old priority */
+ if (remote)
+ ASSERT_OK(setpriority(PRIO_PROCESS, 0, old_prio), "setpriority");
skel_open_load_failure:
close(pipe_c2p[0]);
close(pipe_p2c[1]);
wait(NULL);
}
-static void test_send_signal_tracepoint(bool signal_thread)
+static void test_send_signal_tracepoint(bool signal_thread, bool remote)
{
- test_send_signal_common(NULL, signal_thread);
+ test_send_signal_common(NULL, signal_thread, remote);
}
-static void test_send_signal_perf(bool signal_thread)
+static void test_send_signal_perf(bool signal_thread, bool remote)
{
struct perf_event_attr attr = {
.freq = 1,
@@ -162,10 +217,10 @@ static void test_send_signal_perf(bool signal_thread)
.config = PERF_COUNT_SW_CPU_CLOCK,
};
- test_send_signal_common(&attr, signal_thread);
+ test_send_signal_common(&attr, signal_thread, remote);
}
-static void test_send_signal_nmi(bool signal_thread)
+static void test_send_signal_nmi(bool signal_thread, bool remote)
{
struct perf_event_attr attr = {
.sample_period = 1,
@@ -191,21 +246,35 @@ static void test_send_signal_nmi(bool signal_thread)
close(pmu_fd);
}
- test_send_signal_common(&attr, signal_thread);
+ test_send_signal_common(&attr, signal_thread, remote);
}
void test_send_signal(void)
{
if (test__start_subtest("send_signal_tracepoint"))
- test_send_signal_tracepoint(false);
+ test_send_signal_tracepoint(false, false);
if (test__start_subtest("send_signal_perf"))
- test_send_signal_perf(false);
+ test_send_signal_perf(false, false);
if (test__start_subtest("send_signal_nmi"))
- test_send_signal_nmi(false);
+ test_send_signal_nmi(false, false);
if (test__start_subtest("send_signal_tracepoint_thread"))
- test_send_signal_tracepoint(true);
+ test_send_signal_tracepoint(true, false);
if (test__start_subtest("send_signal_perf_thread"))
- test_send_signal_perf(true);
+ test_send_signal_perf(true, false);
if (test__start_subtest("send_signal_nmi_thread"))
- test_send_signal_nmi(true);
+ test_send_signal_nmi(true, false);
+
+ /* Signal remote thread and thread group */
+ if (test__start_subtest("send_signal_tracepoint_remote"))
+ test_send_signal_tracepoint(false, true);
+ if (test__start_subtest("send_signal_perf_remote"))
+ test_send_signal_perf(false, true);
+ if (test__start_subtest("send_signal_nmi_remote"))
+ test_send_signal_nmi(false, true);
+ if (test__start_subtest("send_signal_tracepoint_thread_remote"))
+ test_send_signal_tracepoint(true, true);
+ if (test__start_subtest("send_signal_perf_thread_remote"))
+ test_send_signal_perf(true, true);
+ if (test__start_subtest("send_signal_nmi_thread_remote"))
+ test_send_signal_nmi(true, true);
}
diff --git a/tools/testing/selftests/bpf/progs/test_send_signal_kern.c b/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
index 92354cd720440..176a355e30624 100644
--- a/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
+++ b/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
@@ -1,27 +1,50 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook
-#include <linux/bpf.h>
+#include <vmlinux.h>
#include <linux/version.h>
#include <bpf/bpf_helpers.h>
-__u32 sig = 0, pid = 0, status = 0, signal_thread = 0;
+struct task_struct *bpf_task_from_pid(int pid) __ksym;
+void bpf_task_release(struct task_struct *p) __ksym;
+int bpf_send_signal_task(struct task_struct *task, int sig, enum pid_type type, u64 value) __ksym;
+
+__u32 sig = 0, pid = 0, status = 0, signal_thread = 0, target_pid = 0;
static __always_inline int bpf_send_signal_test(void *ctx)
{
+ struct task_struct *target_task = NULL;
int ret;
+ u64 value;
if (status != 0 || pid == 0)
return 0;
if ((bpf_get_current_pid_tgid() >> 32) == pid) {
- if (signal_thread)
- ret = bpf_send_signal_thread(sig);
- else
- ret = bpf_send_signal(sig);
+ if (target_pid) {
+ target_task = bpf_task_from_pid(target_pid);
+ if (!target_task)
+ return 0;
+ value = 8;
+ }
+
+ if (signal_thread) {
+ if (target_pid)
+ ret = bpf_send_signal_task(target_task, sig, PIDTYPE_PID, value);
+ else
+ ret = bpf_send_signal_thread(sig);
+ } else {
+ if (target_pid)
+ ret = bpf_send_signal_task(target_task, sig, PIDTYPE_TGID, value);
+ else
+ ret = bpf_send_signal(sig);
+ }
if (ret == 0)
status = 1;
}
+ if (target_task)
+ bpf_task_release(target_task);
+
return 0;
}
--
2.40.1
^ permalink raw reply related [flat|nested] 4+ messages in thread