| Message ID | 20250317-vsock-trans-signal-race-v4-2-fc8837f3f1d4@rbox.co (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | vsock/bpf: Handle races between sockmap update and connect() disconnecting | expand |
On Mon, Mar 17, 2025 at 10:52:24AM +0100, Michal Luczaj wrote: >Racing signal-interrupted connect() and sockmap update may result in an >unconnected (and missing vsock transport) socket in a sockmap. > >Test spends 2 seconds attempting to reach WARN_ON_ONCE(). > >connect > / state = SS_CONNECTED / > sock_map_update_elem > if signal_pending > state = SS_UNCONNECTED > >connect > transport = NULL > vsock_bpf_recvmsg > WARN_ON_ONCE(!vsk->transport) > >Signed-off-by: Michal Luczaj <mhal@rbox.co> >--- > .../selftests/bpf/prog_tests/sockmap_basic.c | 99 ++++++++++++++++++++++ > 1 file changed, 99 insertions(+) LGTM for the vsock part! Acked-by: Stefano Garzarella <sgarzare@redhat.com> > >diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c >index 1e3e4392dcca0e1722c1982ecc649a80c27443b2..2f8bba27866354848f1e30b5473cedb6a85244ff 100644 >--- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c >+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c >@@ -3,6 +3,7 @@ > #include <error.h> > #include <netinet/tcp.h> > #include <sys/epoll.h> >+#include <linux/time64.h> > > #include "test_progs.h" > #include "test_skmsg_load_helpers.skel.h" >@@ -1042,6 +1043,102 @@ static void test_sockmap_vsock_unconnected(void) > xclose(map); > } > >+#define CONNECT_SIGNAL_RACE_TIMEOUT 2 /* seconds */ >+ >+static void sig_handler(int signum) >+{ >+ /* nop */ >+} >+ >+static void connect_signal_racer_cleanup(void *map) >+{ >+ xclose(*(int *)map); >+} >+ >+static void *connect_signal_racer(void *arg) >+{ >+ pid_t pid; >+ int map; >+ >+ map = bpf_map_create(BPF_MAP_TYPE_SOCKMAP, NULL, sizeof(int), >+ sizeof(int), 1, NULL); >+ if (!ASSERT_OK_FD(map, "bpf_map_create")) >+ return NULL; >+ >+ pthread_cleanup_push(connect_signal_racer_cleanup, &map); >+ pid = getpid(); >+ >+ for (;;) { >+ int c = *(int *)arg; >+ int zero = 0; >+ >+ (void)bpf_map_update_elem(map, &zero, &c, BPF_ANY); >+ >+ if (kill(pid, SIGUSR1)) { >+ FAIL_ERRNO("kill"); >+ break; >+ } >+ >+ if ((recv(c, NULL, 0, MSG_DONTWAIT) < 0) && errno == ENODEV) { >+ FAIL_ERRNO("recv"); >+ break; >+ } >+ } >+ >+ pthread_cleanup_pop(1); >+ >+ return NULL; >+} >+ >+static void test_sockmap_vsock_connect_signal_race(void) >+{ >+ struct sockaddr_vm addr, bad_addr; >+ socklen_t alen = sizeof(addr); >+ sighandler_t orig_handler; >+ pthread_t thread; >+ int s, c, p; >+ __u64 tout; >+ >+ orig_handler = signal(SIGUSR1, sig_handler); >+ if (!ASSERT_NEQ(orig_handler, SIG_ERR, "signal handler setup")) >+ return; >+ >+ s = socket_loopback(AF_VSOCK, SOCK_SEQPACKET | SOCK_NONBLOCK); >+ if (s < 0) >+ goto restore; >+ >+ if (xgetsockname(s, (struct sockaddr *)&addr, &alen)) >+ goto close; >+ >+ bad_addr = addr; >+ bad_addr.svm_cid = 0x42424242; /* non-existing */ >+ >+ if (xpthread_create(&thread, 0, connect_signal_racer, &c)) >+ goto close; >+ >+ tout = get_time_ns() + CONNECT_SIGNAL_RACE_TIMEOUT * NSEC_PER_SEC; >+ do { >+ c = xsocket(AF_VSOCK, SOCK_SEQPACKET, 0); >+ if (c < 0) >+ break; >+ >+ if (connect(c, (struct sockaddr *)&addr, alen) && errno == EINTR) >+ (void)connect(c, (struct sockaddr *)&bad_addr, alen); >+ >+ xclose(c); >+ p = accept(s, NULL, NULL); >+ if (p >= 0) >+ xclose(p); >+ } while (get_time_ns() < tout); >+ >+ ASSERT_OK(pthread_cancel(thread), "pthread_cancel"); >+ xpthread_join(thread, NULL); >+close: >+ xclose(s); >+restore: >+ ASSERT_NEQ(signal(SIGUSR1, orig_handler), SIG_ERR, "handler restore"); >+} >+ > void test_sockmap_basic(void) > { > if (test__start_subtest("sockmap create_update_free")) >@@ -1108,4 +1205,6 @@ void test_sockmap_basic(void) > test_sockmap_skb_verdict_vsock_poll(); > if (test__start_subtest("sockmap vsock unconnected")) > test_sockmap_vsock_unconnected(); >+ if (test__start_subtest("sockmap vsock connect signal race")) >+ test_sockmap_vsock_connect_signal_race(); > } > >-- >2.48.1 >
diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c index 1e3e4392dcca0e1722c1982ecc649a80c27443b2..2f8bba27866354848f1e30b5473cedb6a85244ff 100644 --- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c @@ -3,6 +3,7 @@ #include <error.h> #include <netinet/tcp.h> #include <sys/epoll.h> +#include <linux/time64.h> #include "test_progs.h" #include "test_skmsg_load_helpers.skel.h" @@ -1042,6 +1043,102 @@ static void test_sockmap_vsock_unconnected(void) xclose(map); } +#define CONNECT_SIGNAL_RACE_TIMEOUT 2 /* seconds */ + +static void sig_handler(int signum) +{ + /* nop */ +} + +static void connect_signal_racer_cleanup(void *map) +{ + xclose(*(int *)map); +} + +static void *connect_signal_racer(void *arg) +{ + pid_t pid; + int map; + + map = bpf_map_create(BPF_MAP_TYPE_SOCKMAP, NULL, sizeof(int), + sizeof(int), 1, NULL); + if (!ASSERT_OK_FD(map, "bpf_map_create")) + return NULL; + + pthread_cleanup_push(connect_signal_racer_cleanup, &map); + pid = getpid(); + + for (;;) { + int c = *(int *)arg; + int zero = 0; + + (void)bpf_map_update_elem(map, &zero, &c, BPF_ANY); + + if (kill(pid, SIGUSR1)) { + FAIL_ERRNO("kill"); + break; + } + + if ((recv(c, NULL, 0, MSG_DONTWAIT) < 0) && errno == ENODEV) { + FAIL_ERRNO("recv"); + break; + } + } + + pthread_cleanup_pop(1); + + return NULL; +} + +static void test_sockmap_vsock_connect_signal_race(void) +{ + struct sockaddr_vm addr, bad_addr; + socklen_t alen = sizeof(addr); + sighandler_t orig_handler; + pthread_t thread; + int s, c, p; + __u64 tout; + + orig_handler = signal(SIGUSR1, sig_handler); + if (!ASSERT_NEQ(orig_handler, SIG_ERR, "signal handler setup")) + return; + + s = socket_loopback(AF_VSOCK, SOCK_SEQPACKET | SOCK_NONBLOCK); + if (s < 0) + goto restore; + + if (xgetsockname(s, (struct sockaddr *)&addr, &alen)) + goto close; + + bad_addr = addr; + bad_addr.svm_cid = 0x42424242; /* non-existing */ + + if (xpthread_create(&thread, 0, connect_signal_racer, &c)) + goto close; + + tout = get_time_ns() + CONNECT_SIGNAL_RACE_TIMEOUT * NSEC_PER_SEC; + do { + c = xsocket(AF_VSOCK, SOCK_SEQPACKET, 0); + if (c < 0) + break; + + if (connect(c, (struct sockaddr *)&addr, alen) && errno == EINTR) + (void)connect(c, (struct sockaddr *)&bad_addr, alen); + + xclose(c); + p = accept(s, NULL, NULL); + if (p >= 0) + xclose(p); + } while (get_time_ns() < tout); + + ASSERT_OK(pthread_cancel(thread), "pthread_cancel"); + xpthread_join(thread, NULL); +close: + xclose(s); +restore: + ASSERT_NEQ(signal(SIGUSR1, orig_handler), SIG_ERR, "handler restore"); +} + void test_sockmap_basic(void) { if (test__start_subtest("sockmap create_update_free")) @@ -1108,4 +1205,6 @@ void test_sockmap_basic(void) test_sockmap_skb_verdict_vsock_poll(); if (test__start_subtest("sockmap vsock unconnected")) test_sockmap_vsock_unconnected(); + if (test__start_subtest("sockmap vsock connect signal race")) + test_sockmap_vsock_connect_signal_race(); }
Racing signal-interrupted connect() and sockmap update may result in an unconnected (and missing vsock transport) socket in a sockmap. Test spends 2 seconds attempting to reach WARN_ON_ONCE(). connect / state = SS_CONNECTED / sock_map_update_elem if signal_pending state = SS_UNCONNECTED connect transport = NULL vsock_bpf_recvmsg WARN_ON_ONCE(!vsk->transport) Signed-off-by: Michal Luczaj <mhal@rbox.co> --- .../selftests/bpf/prog_tests/sockmap_basic.c | 99 ++++++++++++++++++++++ 1 file changed, 99 insertions(+)