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The following tests: * Fetch FD, and then compare via kcmp * Make sure getfd can be blocked by blocking ptrace_may_access * Making sure fetching bad FDs fails * Make sure trying to set flags to non-zero results in an EINVAL Signed-off-by: Sargun Dhillon <sargun@sargun.me> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/20200107175927.4558-5-sargun@sargun.me Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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Sargun Dhillon
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@@ -2,3 +2,4 @@ pidfd_open_test | |
pidfd_poll_test | ||
pidfd_test | ||
pidfd_wait | ||
pidfd_getfd_test |
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@@ -1,7 +1,7 @@ | ||
# SPDX-License-Identifier: GPL-2.0-only | ||
CFLAGS += -g -I../../../../usr/include/ -pthread | ||
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TEST_GEN_PROGS := pidfd_test pidfd_fdinfo_test pidfd_open_test pidfd_poll_test pidfd_wait | ||
TEST_GEN_PROGS := pidfd_test pidfd_fdinfo_test pidfd_open_test pidfd_poll_test pidfd_wait pidfd_getfd_test | ||
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include ../lib.mk | ||
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@@ -0,0 +1,249 @@ | ||
// SPDX-License-Identifier: GPL-2.0 | ||
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#define _GNU_SOURCE | ||
#include <errno.h> | ||
#include <fcntl.h> | ||
#include <limits.h> | ||
#include <linux/types.h> | ||
#include <sched.h> | ||
#include <signal.h> | ||
#include <stdio.h> | ||
#include <stdlib.h> | ||
#include <string.h> | ||
#include <syscall.h> | ||
#include <sys/prctl.h> | ||
#include <sys/wait.h> | ||
#include <unistd.h> | ||
#include <sys/socket.h> | ||
#include <linux/kcmp.h> | ||
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#include "pidfd.h" | ||
#include "../kselftest.h" | ||
#include "../kselftest_harness.h" | ||
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/* | ||
* UNKNOWN_FD is an fd number that should never exist in the child, as it is | ||
* used to check the negative case. | ||
*/ | ||
#define UNKNOWN_FD 111 | ||
#define UID_NOBODY 65535 | ||
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static int sys_kcmp(pid_t pid1, pid_t pid2, int type, unsigned long idx1, | ||
unsigned long idx2) | ||
{ | ||
return syscall(__NR_kcmp, pid1, pid2, type, idx1, idx2); | ||
} | ||
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static int sys_memfd_create(const char *name, unsigned int flags) | ||
{ | ||
return syscall(__NR_memfd_create, name, flags); | ||
} | ||
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static int __child(int sk, int memfd) | ||
{ | ||
int ret; | ||
char buf; | ||
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/* | ||
* Ensure we don't leave around a bunch of orphaned children if our | ||
* tests fail. | ||
*/ | ||
ret = prctl(PR_SET_PDEATHSIG, SIGKILL); | ||
if (ret) { | ||
fprintf(stderr, "%s: Child could not set DEATHSIG\n", | ||
strerror(errno)); | ||
return -1; | ||
} | ||
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ret = send(sk, &memfd, sizeof(memfd), 0); | ||
if (ret != sizeof(memfd)) { | ||
fprintf(stderr, "%s: Child failed to send fd number\n", | ||
strerror(errno)); | ||
return -1; | ||
} | ||
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/* | ||
* The fixture setup is completed at this point. The tests will run. | ||
* | ||
* This blocking recv enables the parent to message the child. | ||
* Either we will read 'P' off of the sk, indicating that we need | ||
* to disable ptrace, or we will read a 0, indicating that the other | ||
* side has closed the sk. This occurs during fixture teardown time, | ||
* indicating that the child should exit. | ||
*/ | ||
while ((ret = recv(sk, &buf, sizeof(buf), 0)) > 0) { | ||
if (buf == 'P') { | ||
ret = prctl(PR_SET_DUMPABLE, 0); | ||
if (ret < 0) { | ||
fprintf(stderr, | ||
"%s: Child failed to disable ptrace\n", | ||
strerror(errno)); | ||
return -1; | ||
} | ||
} else { | ||
fprintf(stderr, "Child received unknown command %c\n", | ||
buf); | ||
return -1; | ||
} | ||
ret = send(sk, &buf, sizeof(buf), 0); | ||
if (ret != 1) { | ||
fprintf(stderr, "%s: Child failed to ack\n", | ||
strerror(errno)); | ||
return -1; | ||
} | ||
} | ||
if (ret < 0) { | ||
fprintf(stderr, "%s: Child failed to read from socket\n", | ||
strerror(errno)); | ||
return -1; | ||
} | ||
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return 0; | ||
} | ||
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static int child(int sk) | ||
{ | ||
int memfd, ret; | ||
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memfd = sys_memfd_create("test", 0); | ||
if (memfd < 0) { | ||
fprintf(stderr, "%s: Child could not create memfd\n", | ||
strerror(errno)); | ||
ret = -1; | ||
} else { | ||
ret = __child(sk, memfd); | ||
close(memfd); | ||
} | ||
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close(sk); | ||
return ret; | ||
} | ||
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FIXTURE(child) | ||
{ | ||
/* | ||
* remote_fd is the number of the FD which we are trying to retrieve | ||
* from the child. | ||
*/ | ||
int remote_fd; | ||
/* pid points to the child which we are fetching FDs from */ | ||
pid_t pid; | ||
/* pidfd is the pidfd of the child */ | ||
int pidfd; | ||
/* | ||
* sk is our side of the socketpair used to communicate with the child. | ||
* When it is closed, the child will exit. | ||
*/ | ||
int sk; | ||
}; | ||
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FIXTURE_SETUP(child) | ||
{ | ||
int ret, sk_pair[2]; | ||
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ASSERT_EQ(0, socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sk_pair)) { | ||
TH_LOG("%s: failed to create socketpair", strerror(errno)); | ||
} | ||
self->sk = sk_pair[0]; | ||
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self->pid = fork(); | ||
ASSERT_GE(self->pid, 0); | ||
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if (self->pid == 0) { | ||
close(sk_pair[0]); | ||
if (child(sk_pair[1])) | ||
_exit(EXIT_FAILURE); | ||
_exit(EXIT_SUCCESS); | ||
} | ||
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close(sk_pair[1]); | ||
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self->pidfd = sys_pidfd_open(self->pid, 0); | ||
ASSERT_GE(self->pidfd, 0); | ||
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/* | ||
* Wait for the child to complete setup. It'll send the remote memfd's | ||
* number when ready. | ||
*/ | ||
ret = recv(sk_pair[0], &self->remote_fd, sizeof(self->remote_fd), 0); | ||
ASSERT_EQ(sizeof(self->remote_fd), ret); | ||
} | ||
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FIXTURE_TEARDOWN(child) | ||
{ | ||
EXPECT_EQ(0, close(self->pidfd)); | ||
EXPECT_EQ(0, close(self->sk)); | ||
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EXPECT_EQ(0, wait_for_pid(self->pid)); | ||
} | ||
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TEST_F(child, disable_ptrace) | ||
{ | ||
int uid, fd; | ||
char c; | ||
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/* | ||
* Turn into nobody if we're root, to avoid CAP_SYS_PTRACE | ||
* | ||
* The tests should run in their own process, so even this test fails, | ||
* it shouldn't result in subsequent tests failing. | ||
*/ | ||
uid = getuid(); | ||
if (uid == 0) | ||
ASSERT_EQ(0, seteuid(UID_NOBODY)); | ||
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ASSERT_EQ(1, send(self->sk, "P", 1, 0)); | ||
ASSERT_EQ(1, recv(self->sk, &c, 1, 0)); | ||
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fd = sys_pidfd_getfd(self->pidfd, self->remote_fd, 0); | ||
EXPECT_EQ(-1, fd); | ||
EXPECT_EQ(EPERM, errno); | ||
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if (uid == 0) | ||
ASSERT_EQ(0, seteuid(0)); | ||
} | ||
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TEST_F(child, fetch_fd) | ||
{ | ||
int fd, ret; | ||
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fd = sys_pidfd_getfd(self->pidfd, self->remote_fd, 0); | ||
ASSERT_GE(fd, 0); | ||
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EXPECT_EQ(0, sys_kcmp(getpid(), self->pid, KCMP_FILE, fd, self->remote_fd)); | ||
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ret = fcntl(fd, F_GETFD); | ||
ASSERT_GE(ret, 0); | ||
EXPECT_GE(ret & FD_CLOEXEC, 0); | ||
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close(fd); | ||
} | ||
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TEST_F(child, test_unknown_fd) | ||
{ | ||
int fd; | ||
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fd = sys_pidfd_getfd(self->pidfd, UNKNOWN_FD, 0); | ||
EXPECT_EQ(-1, fd) { | ||
TH_LOG("getfd succeeded while fetching unknown fd"); | ||
}; | ||
EXPECT_EQ(EBADF, errno) { | ||
TH_LOG("%s: getfd did not get EBADF", strerror(errno)); | ||
} | ||
} | ||
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TEST(flags_set) | ||
{ | ||
ASSERT_EQ(-1, sys_pidfd_getfd(0, 0, 1)); | ||
EXPECT_EQ(errno, EINVAL); | ||
} | ||
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#if __NR_pidfd_getfd == -1 | ||
int main(void) | ||
{ | ||
fprintf(stderr, "__NR_pidfd_getfd undefined. The pidfd_getfd syscall is unavailable. Test aborting\n"); | ||
return KSFT_SKIP; | ||
} | ||
#else | ||
TEST_HARNESS_MAIN | ||
#endif |