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selftests/seccomp: check that a zombie leader doesn't affect others

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Ensure that a dead thread leader doesn't prevent installing new filters
with SECCOMP_FILTER_FLAG_TSYNC from other threads.

Signed-off-by: Andrei Vagin <avagin@google.com>
Link: https://lore.kernel.org/r/20240628021014.231976-5-avagin@google.com
Reviewed-by: Tycho Andersen <tandersen@netflix.com>
Signed-off-by: Kees Cook <kees@kernel.org>
This commit is contained in:
Andrei Vagin 2024-06-28 02:10:14 +00:00 committed by Kees Cook
parent 39a73b4aa6
commit f0c508faea
1 changed files with 77 additions and 0 deletions
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77
tools/testing/selftests/seccomp/seccomp_bpf.c
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@ -4809,6 +4809,83 @@ TEST(user_notification_wait_killable_fatal)
EXPECT_EQ(SIGTERM, WTERMSIG(status));
}
struct tsync_vs_thread_leader_args {
pthread_t leader;
};
static void *tsync_vs_dead_thread_leader_sibling(void *_args)
{
struct sock_filter allow_filter[] = {
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
};
struct sock_fprog allow_prog = {
.len = (unsigned short)ARRAY_SIZE(allow_filter),
.filter = allow_filter,
};
struct tsync_vs_thread_leader_args *args = _args;
void *retval;
long ret;
ret = pthread_join(args->leader, &retval);
if (ret)
exit(1);
if (retval != _args)
exit(2);
ret = seccomp(SECCOMP_SET_MODE_FILTER, SECCOMP_FILTER_FLAG_TSYNC, &allow_prog);
if (ret)
exit(3);
exit(0);
}
/*
* Ensure that a dead thread leader doesn't prevent installing new filters with
* SECCOMP_FILTER_FLAG_TSYNC from other threads.
*/
TEST(tsync_vs_dead_thread_leader)
{
int status;
pid_t pid;
long ret;
ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
ASSERT_EQ(0, ret) {
TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS!");
}
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0) {
struct sock_filter allow_filter[] = {
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
};
struct sock_fprog allow_prog = {
.len = (unsigned short)ARRAY_SIZE(allow_filter),
.filter = allow_filter,
};
struct tsync_vs_thread_leader_args *args;
pthread_t sibling;
args = malloc(sizeof(*args));
ASSERT_NE(NULL, args);
args->leader = pthread_self();
ret = pthread_create(&sibling, NULL,
tsync_vs_dead_thread_leader_sibling, args);
ASSERT_EQ(0, ret);
/* Install a new filter just to the leader thread. */
ret = seccomp(SECCOMP_SET_MODE_FILTER, 0, &allow_prog);
ASSERT_EQ(0, ret);
pthread_exit(args);
exit(1);
}
EXPECT_EQ(pid, waitpid(pid, &status, 0));
EXPECT_EQ(0, status);
}
/*
* TODO:
* - expand NNP testing