[Devel] [PATCH vz10] tests: add ve_printk selftest
Aleksei Oladko
aleksey.oladko at virtuozzo.com
Wed Nov 26 23:04:56 MSK 2025
Add selftests for the printk virtualization feature. The new tests cover
ve_printk, ve_printk_ratelimited, net_ve_ratelimited, and log buffer
overflow handling.
https://virtuozzo.atlassian.net/browse/VSTOR-114252
Signed-off-by: Aleksei Oladko <aleksey.oladko at virtuozzo.com>
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/ve_printk/.gitignore | 3 +
tools/testing/selftests/ve_printk/Makefile | 8 +
tools/testing/selftests/ve_printk/test_segf.c | 12 +
tools/testing/selftests/ve_printk/test_trap.c | 5 +
.../selftests/ve_printk/ve_printk_test.c | 593 ++++++++++++++++++
6 files changed, 622 insertions(+)
create mode 100644 tools/testing/selftests/ve_printk/.gitignore
create mode 100644 tools/testing/selftests/ve_printk/Makefile
create mode 100644 tools/testing/selftests/ve_printk/test_segf.c
create mode 100644 tools/testing/selftests/ve_printk/test_trap.c
create mode 100644 tools/testing/selftests/ve_printk/ve_printk_test.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 363d031a16f7..7334fb207676 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -113,6 +113,7 @@ TARGETS += tty
TARGETS += uevent
TARGETS += user_events
TARGETS += vDSO
+TARGETS += ve_printk
TARGETS += mm
TARGETS += x86
TARGETS += zram
diff --git a/tools/testing/selftests/ve_printk/.gitignore b/tools/testing/selftests/ve_printk/.gitignore
new file mode 100644
index 000000000000..a4ad6620b803
--- /dev/null
+++ b/tools/testing/selftests/ve_printk/.gitignore
@@ -0,0 +1,3 @@
+ve_printk_test
+test_segf
+test_trap
diff --git a/tools/testing/selftests/ve_printk/Makefile b/tools/testing/selftests/ve_printk/Makefile
new file mode 100644
index 000000000000..e3edcbacda1e
--- /dev/null
+++ b/tools/testing/selftests/ve_printk/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for ve_printk selftests.
+CFLAGS = -g -I../../../../usr/include/ -Wall -O2
+
+TEST_GEN_PROGS += ve_printk_test
+TEST_GEN_FILES += test_segf test_trap
+
+include ../lib.mk
diff --git a/tools/testing/selftests/ve_printk/test_segf.c b/tools/testing/selftests/ve_printk/test_segf.c
new file mode 100644
index 000000000000..cdc89068ca06
--- /dev/null
+++ b/tools/testing/selftests/ve_printk/test_segf.c
@@ -0,0 +1,12 @@
+#include <stdio.h>
+#include <unistd.h>
+
+int main(void)
+{
+ int *p = (int *)0xffffffffffffff00;
+
+ printf("%d\n", getpid());
+ fflush(stdout);
+ *p = 1;
+ return 0;
+}
diff --git a/tools/testing/selftests/ve_printk/test_trap.c b/tools/testing/selftests/ve_printk/test_trap.c
new file mode 100644
index 000000000000..b774e2b9484c
--- /dev/null
+++ b/tools/testing/selftests/ve_printk/test_trap.c
@@ -0,0 +1,5 @@
+int main(void)
+{
+ __asm__("int3");
+ return 0;
+}
diff --git a/tools/testing/selftests/ve_printk/ve_printk_test.c b/tools/testing/selftests/ve_printk/ve_printk_test.c
new file mode 100644
index 000000000000..78475ff71faa
--- /dev/null
+++ b/tools/testing/selftests/ve_printk/ve_printk_test.c
@@ -0,0 +1,593 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <linux/sched.h>
+#include <time.h>
+#include <sched.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/mount.h>
+#include <linux/limits.h>
+#include <errno.h>
+
+#include "../kselftest_harness.h"
+
+#define __STACK_SIZE (8 * 1024 * 1024)
+#define CTID_MIN 108
+#define CTID_MAX 200
+#define SEGFAULT_PROG "test_segf"
+#define TRAP_PROG "test_trap"
+#define TEST_RATELIMIT_BURST 10
+#define TEST_RATELIMIT 5
+
+static int has_substr(char *buf, const char *str)
+{
+ char *token;
+ char *str_ptr = buf;
+
+ while ((token = strsep(&str_ptr, ",")) != NULL) {
+ if (!strcmp(token, str))
+ return 1;
+ }
+ return 0;
+}
+
+static int get_mount_path(const char *fstype, const char *subsys, char *out, int size)
+{
+ FILE *fp;
+ int n;
+ char buf[PATH_MAX];
+ char target[4096];
+ char ops[4096];
+ char format[4096];
+ int ret = 1;
+
+ snprintf(format, sizeof(format), "%%*s %%4095s %s %%4095s", fstype);
+
+ fp = fopen("/proc/mounts", "r");
+ if (fp == NULL)
+ return -1;
+
+ while (fgets(buf, sizeof(buf), fp)) {
+ n = sscanf(buf, format, target, ops);
+ if (n != 2)
+ continue;
+ if (subsys == NULL || has_substr(ops, subsys)) {
+ strncpy(out, target, size);
+ out[size-1] = '\0';
+ ret = 0;
+ break;
+ }
+ }
+ fclose(fp);
+
+ return ret;
+}
+
+FIXTURE(ve_printk)
+{
+ char cgv2_path[PATH_MAX];
+ char cgve_path[PATH_MAX];
+ int ctid;
+};
+
+FIXTURE_SETUP(ve_printk)
+{
+ char path[PATH_MAX * 2];
+
+ ASSERT_EQ(get_mount_path("cgroup2", NULL, self->cgv2_path, sizeof(self->cgv2_path)), 0);
+ ASSERT_EQ(get_mount_path("cgroup", "ve", self->cgve_path, sizeof(self->cgve_path)), 0);
+
+ self->ctid = CTID_MIN;
+ while (self->ctid < CTID_MAX) {
+ snprintf(path, sizeof(path), "%s/%d", self->cgve_path, self->ctid);
+ if (access(path, F_OK) && errno == ENOENT) {
+ snprintf(path, sizeof(path), "%s/%d", self->cgv2_path, self->ctid);
+ if (access(path, F_OK)) {
+ break;
+ }
+ }
+ self->ctid++;
+ }
+ ASSERT_LT(self->ctid, CTID_MAX);
+
+ snprintf(path, sizeof(path), "%s/%d", self->cgv2_path, self->ctid);
+ ASSERT_EQ(mkdir(path, 0755), 0);
+ snprintf(path, sizeof(path), "%s/%d", self->cgve_path, self->ctid);
+ ASSERT_EQ(mkdir(path, 0755), 0);
+ snprintf(path, sizeof(path), "echo %d > %s/%d/ve.veid",
+ self->ctid, self->cgve_path, self->ctid);
+ ASSERT_EQ(system(path), 0);
+};
+
+FIXTURE_TEARDOWN(ve_printk)
+{
+ char path[PATH_MAX * 2];
+
+ snprintf(path, sizeof(path), "%s/%d/vz.slice", self->cgv2_path, self->ctid);
+ rmdir(path);
+ snprintf(path, sizeof(path), "%s/%d", self->cgv2_path, self->ctid);
+ rmdir(path);
+ snprintf(path, sizeof(path), "%s/%d", self->cgve_path, self->ctid);
+ rmdir(path);
+}
+
+int setup_timens(void)
+{
+ int ret, fd;
+
+ if (access("/proc/self/timens_offsets", F_OK))
+ return 0;
+
+ if (unshare(CLONE_NEWTIME)) {
+ return -1;
+ }
+
+ fd = open("/proc/self/ns/time_for_children", O_RDONLY);
+ if (fd < 0) {
+ return -1;
+ }
+
+ ret = setns(fd, CLONE_NEWTIME);
+
+ close(fd);
+ return ret;
+}
+
+struct fargs {
+ char *cgve;
+ int ctid;
+ int test;
+};
+
+enum {
+ TEST_LOG,
+ TEST_LOGV0,
+ TEST_LOGBOTH,
+ TEST_PR_RATELIMIT,
+ TEST_OVERFLOW,
+};
+
+int ve_printk_test_logct(void)
+{
+ FILE *pdmesg;
+ char buf[1024];
+ char str[256];
+ FILE *f;
+ int pid;
+ int ret = 2;
+
+ f = popen("./" SEGFAULT_PROG, "r");
+ if (!f)
+ return -1;
+
+ if (fscanf(f, "%d", &pid) != 1) {
+ pclose(f);
+ return -1;
+ }
+ pclose(f);
+
+ pdmesg = popen("dmesg", "r");
+ if (!pdmesg)
+ return -1;
+
+ snprintf(str, sizeof(str), "%s[%d]: segfault at", SEGFAULT_PROG, pid);
+ while (fgets(buf, sizeof(buf), pdmesg)) {
+ if (ret == 2 && strstr(buf, str)) {
+ ret = 1;
+ }
+ if (ret == 1 && strstr(buf, "Code: ")) {
+ ret = 0;
+ break;
+ }
+ }
+ pclose(pdmesg);
+ return ret;
+}
+
+int ve_printk_test_logve0(void)
+{
+ FILE *pdmesg;
+ char buf[1024];
+ int ret = 0;
+
+ /* do_trap -> show_signal -> print_vma_addr -> ve_print_vma_addr(VE0_LOG, ... */
+ system("./" TRAP_PROG);
+
+ pdmesg = popen("dmesg", "r");
+ if (!pdmesg)
+ return -1;
+
+ while (fgets(buf, sizeof(buf), pdmesg)) {
+ if (strstr(buf, "traps: test_trap[") &&
+ strstr(buf, " in test_trap[")) {
+ ret = 1;
+ break;
+ }
+ }
+ pclose(pdmesg);
+ return ret;
+}
+
+int ve_printk_test_logboth(void)
+{
+ FILE *pdmesg;
+ char buf[1024];
+ int ret = TEST_RATELIMIT_BURST;
+
+ system("ip link set up dev lo");
+ /*
+ * Reduce the connection tracking table size to 2. After two ping calls the
+ * table will be full, and all new packets will trigger
+ * net_veboth_ratelimited
+ */
+ system("echo 2 > /proc/sys/net/nf_conntrack_max");
+ system("iptables -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT");
+ system("ping -q -c 1 -w 1 127.0.0.1 > /dev/null");
+ system("ping -q -c 1 -w 1 127.0.0.1 > /dev/null");
+ /* net_veboth_ratelimited */
+ system("ping -q -c 100 -w 1 -i 0.0001 127.0.0.1 > /dev/null");
+
+ pdmesg = popen("dmesg", "r");
+ if (!pdmesg)
+ return -1;
+
+ while (fgets(buf, sizeof(buf), pdmesg)) {
+ if (strstr(buf, "nf_conntrack table full, dropping packet")) {
+ ret--;
+ }
+ }
+ pclose(pdmesg);
+ return ret;
+}
+
+int ve_printk_test_ratelimit(void)
+{
+ FILE *pdmesg;
+ char buf[1024];
+ int ret = TEST_RATELIMIT_BURST + 1;
+ int supressed = 1;
+ int i;
+
+ /* reject_tg_check -> ve_printk_ratelimited(VE_LOG, ... */
+ for (i = 0; i < 2 * TEST_RATELIMIT_BURST; i++) {
+ system("iptables -A INPUT -s 10.20.30.40 -j REJECT --reject-with tcp-reset &> /dev/null");
+ }
+ sleep(TEST_RATELIMIT + 1);
+ system("iptables -A INPUT -s 10.20.30.40 -j REJECT --reject-with tcp-reset &> /dev/null");
+
+ pdmesg = popen("dmesg", "r");
+ if (!pdmesg)
+ return -1;
+
+ while (fgets(buf, sizeof(buf), pdmesg)) {
+ if (strstr(buf, "TCP_RESET invalid for non-tcp")) {
+ ret--;
+ }
+ if (strstr(buf, "reject_tg_check") && strstr(buf, "callbacks suppressed"))
+ supressed--;
+ }
+ pclose(pdmesg);
+
+ return ret + supressed;
+}
+
+int ve_printk_test_overflow(void)
+{
+ int i;
+
+ /*
+ * Ten program segfaults are enough to overflow the container's log buffer
+ * Run 15 to ensure the buffer is actually overflowed.
+ */
+ for (i = 0; i < 15; i++) {
+ system("./" SEGFAULT_PROG " > /dev/null");
+ /* bypass printk_ratelimit */
+ if (i == 9)
+ sleep(5);
+ }
+ return ve_printk_test_logct();
+}
+
+int child_func(void *arg)
+{
+ int ret;
+ int fd;
+ struct fargs *args = (struct fargs *)arg;
+ char cg_state[PATH_MAX];
+
+ ret = setup_timens();
+ if (ret)
+ return ret;
+
+ snprintf(cg_state, sizeof(cg_state), "%s/%d/ve.state", args->cgve, args->ctid);
+
+ (void)umount2("/proc", MNT_DETACH);
+ ret = mount("proc", "/proc", "proc", 0, NULL);
+ if (ret < 0)
+ return ret;
+
+ fd = open("/proc/self/uid_map", O_WRONLY);
+ if (fd < 0)
+ return -1;
+ write(fd, "0 0 1\n", 6);
+ close(fd);
+
+ fd = open("/proc/self/gid_map", O_WRONLY);
+ if (fd < 0)
+ return -1;
+ write(fd, "0 0 1\n", 6);
+ close(fd);
+
+ fd = open(cg_state, O_WRONLY);
+ if (fd < 0) {
+ return -1;
+ }
+
+ if (write(fd, "START", strlen("START")) < 0) {
+ close(fd);
+ return -1;
+ }
+
+ close(fd);
+
+ switch(args->test) {
+ case TEST_LOG:
+ ret = ve_printk_test_logct();
+ break;
+ case TEST_LOGV0:
+ ret = ve_printk_test_logve0();
+ break;
+ case TEST_LOGBOTH:
+ ret = ve_printk_test_logboth();
+ break;
+ case TEST_PR_RATELIMIT:
+ ret = ve_printk_test_ratelimit();
+ break;
+ case TEST_OVERFLOW:
+ ret = ve_printk_test_overflow();
+ break;
+ default:
+ ret = -1;
+ }
+ return ret;
+}
+
+int enter_cgroup(const char *cgroup, int ctid)
+{
+ char cg_path[PATH_MAX];
+ char pid_str[64];
+ int fd;
+ int ret = 0;
+
+ if (ctid)
+ snprintf(cg_path, sizeof(cg_path), "%s/%d/cgroup.procs", cgroup, ctid);
+ else
+ snprintf(cg_path, sizeof(cg_path), "%s/cgroup.procs", cgroup);
+ snprintf(pid_str, sizeof(pid_str), "%d", getpid());
+ fd = open(cg_path, O_WRONLY);
+ if (fd < 0) {
+ return -1;
+ }
+
+ if (write(fd, pid_str, strlen(pid_str)) < 0) {
+ ret = -1;
+ }
+
+ close(fd);
+ return ret;
+}
+
+int run_vzct(char *cgv2, char *cgve, int ctid, int testid)
+{
+ char *stack;
+ char *stack_top;
+ pid_t pid;
+ int flags = CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
+ CLONE_NEWPID | CLONE_NEWUSER | CLONE_NEWNET |
+ CLONE_NEWCGROUP | SIGCHLD;
+ struct fargs args = {
+ .cgve = cgve,
+ .ctid = ctid,
+ .test = testid,
+ };
+ int status;
+ int ret;
+
+ stack = malloc(__STACK_SIZE);
+ if (!stack)
+ return -1;
+
+ ret = enter_cgroup(cgv2, ctid);
+ if (ret < 0)
+ return -1;
+ ret = enter_cgroup(cgve, ctid);
+ if (ret < 0)
+ return -1;
+
+ stack_top = stack + __STACK_SIZE;
+ pid = clone(child_func, stack_top, flags, &args);
+ if (pid < 0) {
+ return -1;
+ }
+
+ ret = waitpid(pid, &status, 0);
+ if (ret < 0)
+ return -1;
+ ret = -1;
+ if (WIFEXITED(status)) {
+ ret = WEXITSTATUS(status);
+ }
+ enter_cgroup(cgv2, 0);
+ enter_cgroup(cgve, 0);
+
+ return ret;
+}
+
+FILE *open_dmesg(void)
+{
+ int fd;
+ FILE *fdmesg;
+ char buf[1024];
+
+ fd = open("/dev/kmsg", O_RDONLY | O_NONBLOCK);
+ if (fd < 0)
+ return NULL;
+ fdmesg = fdopen(fd, "r");
+ if (!fdmesg)
+ return NULL;
+
+ while (fgets(buf, sizeof(buf), fdmesg)) ;
+ return fdmesg;
+}
+
+int restore_param(const char *path, int val)
+{
+ int fd;
+ char str[16];
+
+ fd = open(path, O_WRONLY);
+ if (fd < 0)
+ return -1;
+ snprintf(str, sizeof(str), "%d", val);
+ write(fd, str, strlen(str));
+ close(fd);
+
+ return 0;
+}
+
+int set_param(const char *path, int val, int *old)
+{
+ FILE *f;
+
+ f = fopen(path, "r");
+ if (!f)
+ return -1;
+ if (fscanf(f, "%u", old) != 1) {
+ fclose(f);
+ return -1;
+ }
+ fclose(f);
+ if (*old == val)
+ return 0;
+ return restore_param(path, val);
+}
+
+TEST_F(ve_printk, ve_log)
+{
+ int ret;
+ FILE *fdmesg;
+ char buf[1024];
+ int old;
+
+ ASSERT_EQ(set_param("/proc/sys/debug/exception-trace", 1, &old), 0);
+ fdmesg = open_dmesg();
+ ASSERT_NE(fdmesg, NULL);
+
+ ret = run_vzct(self->cgv2_path, self->cgve_path, self->ctid, TEST_LOG);
+ ASSERT_EQ(ret, 0);
+
+ while (fgets(buf, sizeof(buf), fdmesg)) {
+ ASSERT_EQ(strstr(buf, SEGFAULT_PROG) && strstr(buf, "segfault at"), false);
+ EXPECT_EQ(strstr(buf, "Code: "), NULL);
+ }
+ fclose(fdmesg);
+ restore_param("/proc/sys/debug/exception-trace", old);
+}
+
+TEST_F(ve_printk, ve0_log)
+{
+ int ret;
+ FILE *fdmesg;
+ char buf[1024];
+ int ex_trace;
+
+ ASSERT_EQ(set_param("/proc/sys/debug/exception-trace", 1, &ex_trace), 0);
+ fdmesg = open_dmesg();
+ ASSERT_NE(fdmesg, NULL);
+
+ ret = run_vzct(self->cgv2_path, self->cgve_path, self->ctid, TEST_LOGV0);
+ ASSERT_EQ(ret, 0);
+
+ while (fgets(buf, sizeof(buf), fdmesg)) {
+ if (strstr(buf, "traps: test_trap[") &&
+ strstr(buf, " in test_trap[")) {
+ ret = 1;
+ break;
+ }
+ }
+ fclose(fdmesg);
+ restore_param("/proc/sys/debug/exception-trace", ex_trace);
+ ASSERT_EQ(ret, 1);
+}
+
+TEST_F(ve_printk, ve_log_both)
+{
+ int ret;
+ FILE *fdmesg;
+ char buf[1024];
+ int old_ratelimit;
+
+ ASSERT_EQ(set_param("/proc/sys/net/core/message_burst",
+ TEST_RATELIMIT_BURST, &old_ratelimit), 0);
+ fdmesg = open_dmesg();
+ ASSERT_NE(fdmesg, NULL);
+
+ ret = run_vzct(self->cgv2_path, self->cgve_path, self->ctid, TEST_LOGBOTH);
+ ASSERT_EQ(ret, 0);
+
+ while (fgets(buf, sizeof(buf), fdmesg)) {
+ if (strstr(buf, "nf_conntrack table full, dropping packet")) {
+ ret++;
+ }
+ }
+ fclose(fdmesg);
+ restore_param("/proc/sys/kernel/printk_ratelimit_burst", old_ratelimit);
+ ASSERT_EQ(ret, TEST_RATELIMIT_BURST);
+}
+
+TEST_F(ve_printk, ve_printk_ratelimited)
+{
+ int ret;
+ FILE *fdmesg;
+ char buf[1024];
+ int old_ratelimit_burst;
+ int old_ratelimit;
+
+ ASSERT_EQ(set_param("/proc/sys/net/core/message_burst",
+ TEST_RATELIMIT_BURST, &old_ratelimit_burst), 0);
+ ASSERT_EQ(set_param("/proc/sys/net/core/message_cost",
+ TEST_RATELIMIT, &old_ratelimit), 0);
+ fdmesg = open_dmesg();
+ ASSERT_NE(fdmesg, NULL);
+
+ ret = run_vzct(self->cgv2_path, self->cgve_path, self->ctid, TEST_PR_RATELIMIT);
+ ASSERT_EQ(ret, 0);
+
+ while (fgets(buf, sizeof(buf), fdmesg)) {
+ ASSERT_EQ(strstr(buf, "reject_tg_check") && strstr(buf, "callbacks suppressed"), false);
+ ASSERT_EQ(strstr(buf, "TCP_RESET invalid for non-tcp"), NULL);
+ }
+ fclose(fdmesg);
+ restore_param("/proc/sys/kernel/printk_ratelimit_burst", old_ratelimit_burst);
+ restore_param("/proc/sys/net/core/message_cost", old_ratelimit);
+}
+
+TEST_F(ve_printk, ve_printk_overflow)
+{
+ int ret;
+ int ex_trace;
+
+ ASSERT_EQ(set_param("/proc/sys/debug/exception-trace", 1, &ex_trace), 0);
+
+ ret = run_vzct(self->cgv2_path, self->cgve_path, self->ctid, TEST_OVERFLOW);
+ ASSERT_EQ(ret, 0);
+ restore_param("/proc/sys/debug/exception-trace", ex_trace);
+
+}
+
+TEST_HARNESS_MAIN
--
2.43.0
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