[PATCH v5 4/4] test: add a test for the process_vmsplice syscall

Mike Rapoport
2018-01-09T06:31:22Z

From: Andrei Vagin <avagin@openvz.org>

This test checks that process_vmsplice() can splice pages from a remote
process and returns EFAULT, if process_vmsplice() tries to splice pages
by an unaccessiable address.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
---
tools/testing/selftests/process_vmsplice/Makefile | 5 +
.../process_vmsplice/process_vmsplice_test.c | 196 +++++++++++++++++++++
2 files changed, 201 insertions(+)
create mode 100644 tools/testing/selftests/process_vmsplice/Makefile
create mode 100644 tools/testing/selftests/process_vmsplice/process_vmsplice_test.c

diff --git a/tools/testing/selftests/process_vmsplice/Makefile b/tools/testing/selftests/process_vmsplice/Makefile
new file mode 100644
index 000000000000..246d5a7dfed6
--- /dev/null
+++ b/tools/testing/selftests/process_vmsplice/Makefile
@@ -0,0 +1,5 @@
+CFLAGS += -I../../../../usr/include/
+
+TEST_GEN_PROGS := process_vmsplice_test
+
+include ../lib.mk
diff --git a/tools/testing/selftests/process_vmsplice/process_vmsplice_test.c b/tools/testing/selftests/process_vmsplice/process_vmsplice_test.c
new file mode 100644
index 000000000000..1682bdb32de3
--- /dev/null
+++ b/tools/testing/selftests/process_vmsplice/process_vmsplice_test.c
@@ -0,0 +1,196 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <fcntl.h>
+#include <sys/uio.h>
+#include <errno.h>
+#include <signal.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+
+#include "../kselftest.h"
+
+#ifndef __NR_process_vmsplice
+#define __NR_process_vmsplice 333
+#endif
+
+#define pr_err(fmt, ...) \
+ ({ \
+ fprintf(stderr, "%s:%d:" fmt, \
+ __func__, __LINE__, ##__VA_ARGS__); \
+ KSFT_FAIL; \
+ })
+#define pr_perror(fmt, ...) pr_err(fmt ": %m\n", ##__VA_ARGS__)
+#define fail(fmt, ...) pr_err("FAIL:" fmt, ##__VA_ARGS__)
+
+static ssize_t process_vmsplice(pid_t pid, int fd, const struct iovec *iov,
+ unsigned long nr_segs, unsigned int flags)
+{
+ return syscall(__NR_process_vmsplice, pid, fd, iov, nr_segs, flags);
+
+}
+
+#define MEM_SIZE (4096 * 100)
+#define MEM_WRONLY_SIZE (4096 * 10)
+
+int main(int argc, char **argv)
+{
+ char *addr, *addr_wronly;
+ int p[2];
+ struct iovec iov[2];
+ char buf[4096];
+ int status, ret;
+ pid_t pid;
+
+ ksft_print_header();
+
+ if (process_vmsplice(0, 0, 0, 0, 0)) {
+ if (errno == ENOSYS) {
+ ksft_exit_skip("process_vmsplice is not supported\n");
+ return 0;
+ }
+ return pr_perror("Zero-length process_vmsplice failed");
+ }
+
+ addr = mmap(0, MEM_SIZE, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+ if (addr == MAP_FAILED)
+ return pr_perror("Unable to create a mapping");
+
+ addr_wronly = mmap(0, MEM_WRONLY_SIZE, PROT_WRITE,
+ MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+ if (addr_wronly == MAP_FAILED)
+ return pr_perror("Unable to create a write-only mapping");
+
+ if (pipe(p))
+ return pr_perror("Unable to create a pipe");
+
+ pid = fork();
+ if (pid < 0)
+ return pr_perror("Unable to fork");
+
+ if (pid == 0) {
+ addr[0] = 'C';
+ addr[4096 + 128] = 'A';
+ addr[4096 + 128 + 4096 - 1] = 'B';
+
+ if (prctl(PR_SET_PDEATHSIG, SIGKILL))
+ return pr_perror("Unable to set PR_SET_PDEATHSIG");
+ if (write(p[1], "c", 1) != 1)
+ return pr_perror("Unable to write data into pipe");
+
+ while (1)
+ sleep(1);
+ return 1;
+ }
+ if (read(p[0], buf, 1) != 1) {
+ pr_perror("Unable to read data from pipe");
+ kill(pid, SIGKILL);
+ wait(&status);
+ return 1;
+ }
+
+ munmap(addr, MEM_SIZE);
+ munmap(addr_wronly, MEM_WRONLY_SIZE);
+
+ iov[0].iov_base = addr;
+ iov[0].iov_len = 1;
+
+ iov[1].iov_base = addr + 4096 + 128;
+ iov[1].iov_len = 4096;
+
+ /* check one iovec */
+ if (process_vmsplice(pid, p[1], iov, 1, SPLICE_F_GIFT) != 1)
+ return pr_perror("Unable to splice pages");
+
+ if (read(p[0], buf, 1) != 1)
+ return pr_perror("Unable to read from pipe");
+
+ if (buf[0] != 'C')
+ ksft_test_result_fail("Get wrong data\n");
+ else
+ ksft_test_result_pass("Check process_vmsplice with one vec\n");
+
+ /* check two iovec-s */
+ if (process_vmsplice(pid, p[1], iov, 2, SPLICE_F_GIFT) != 4097)
+ return pr_perror("Unable to spice pages\n");
+
+ if (read(p[0], buf, 1) != 1)
+ return pr_perror("Unable to read from pipe\n");
+
+ if (buf[0] != 'C')
+ ksft_test_result_fail("Get wrong data\n");
+
+ if (read(p[0], buf, 4096) != 4096)
+ return pr_perror("Unable to read from pipe\n");
+
+ if (buf[0] != 'A' || buf[4095] != 'B')
+ ksft_test_result_fail("Get wrong data\n");
+ else
+ ksft_test_result_pass("check process_vmsplice with two vecs\n");
+
+ /* check how an unreadable region in a second vec is handled */
+ iov[0].iov_base = addr;
+ iov[0].iov_len = 1;
+
+ iov[1].iov_base = addr_wronly + 5;
+ iov[1].iov_len = 1;
+
+ if (process_vmsplice(pid, p[1], iov, 2, SPLICE_F_GIFT) != 1)
+ return pr_perror("Unable to splice data");
+
+ if (read(p[0], buf, 1) != 1)
+ return pr_perror("Unable to read form pipe");
+
+ if (buf[0] != 'C')
+ ksft_test_result_fail("Get wrong data\n");
+ else
+ ksft_test_result_pass("unreadable region in a second vec\n");
+
+ /* check how an unreadable region in a first vec is handled */
+ errno = 0;
+ if (process_vmsplice(pid, p[1], iov + 1, 1, SPLICE_F_GIFT) != -1 ||
+ errno != EFAULT)
+ ksft_test_result_fail("Got anexpected errno %d\n", errno);
+ else
+ ksft_test_result_pass("splice as much as possible\n");
+
+ iov[0].iov_base = addr;
+ iov[0].iov_len = 1;
+
+ iov[1].iov_base = addr;
+ iov[1].iov_len = MEM_SIZE;
+
+ /* splice as much as possible */
+ ret = process_vmsplice(pid, p[1], iov, 2,
+ SPLICE_F_GIFT | SPLICE_F_NONBLOCK);
+ if (ret != 4096 * 15 + 1) /* by default a pipe can fit 16 pages */
+ return pr_perror("Unable to splice pages");
+
+ while (ret > 0) {
+ int len;
+
+ len = read(p[0], buf, 4096);
+ if (len < 0)
+ return pr_perror("Unable to read data");
+ if (len > ret)
+ return pr_err("Read more than expected\n");
+ ret -= len;
+ }
+ ksft_test_result_pass("splice as much as possible\n");
+
+ if (kill(pid, SIGTERM))
+ return pr_perror("Unable to kill a child process");
+ status = -1;
+ if (wait(&status) < 0)
+ return pr_perror("Unable to wait a child process");
+ if (!WIFSIGNALED(status) || WTERMSIG(status) != SIGTERM)
+ return pr_err("The child exited with an unexpected code %d\n",
+ status);
+
+ if (ksft_get_fail_cnt())
+ return ksft_exit_fail();
+ return ksft_exit_pass();
+}
--
2.7.4