diff options
Diffstat (limited to 'tools/testing/selftests/pid_namespace')
| -rw-r--r-- | tools/testing/selftests/pid_namespace/.gitignore | 1 | ||||
| -rw-r--r-- | tools/testing/selftests/pid_namespace/Makefile | 2 | ||||
| -rw-r--r-- | tools/testing/selftests/pid_namespace/pid_max.c | 156 | ||||
| -rw-r--r-- | tools/testing/selftests/pid_namespace/pidns_init_via_setns.c | 238 |
4 files changed, 364 insertions, 33 deletions
diff --git a/tools/testing/selftests/pid_namespace/.gitignore b/tools/testing/selftests/pid_namespace/.gitignore index 5118f0f3edf4..c647c6eb3367 100644 --- a/tools/testing/selftests/pid_namespace/.gitignore +++ b/tools/testing/selftests/pid_namespace/.gitignore @@ -1,2 +1,3 @@ pid_max +pidns_init_via_setns regression_enomem diff --git a/tools/testing/selftests/pid_namespace/Makefile b/tools/testing/selftests/pid_namespace/Makefile index b972f55d07ae..b01a924ac04b 100644 --- a/tools/testing/selftests/pid_namespace/Makefile +++ b/tools/testing/selftests/pid_namespace/Makefile @@ -1,7 +1,7 @@ # SPDX-License-Identifier: GPL-2.0 CFLAGS += -g $(KHDR_INCLUDES) -TEST_GEN_PROGS = regression_enomem pid_max +TEST_GEN_PROGS = regression_enomem pid_max pidns_init_via_setns LOCAL_HDRS += $(selfdir)/pidfd/pidfd.h diff --git a/tools/testing/selftests/pid_namespace/pid_max.c b/tools/testing/selftests/pid_namespace/pid_max.c index c9519e7385b6..5d686a09aa15 100644 --- a/tools/testing/selftests/pid_namespace/pid_max.c +++ b/tools/testing/selftests/pid_namespace/pid_max.c @@ -12,10 +12,74 @@ #include <syscall.h> #include <sys/mount.h> #include <sys/wait.h> +#include <unistd.h> #include "kselftest_harness.h" #include "../pidfd/pidfd.h" +/* + * The kernel computes the minimum allowed pid_max as: + * max(RESERVED_PIDS + 1, PIDS_PER_CPU_MIN * num_possible_cpus()) + * Mirror that here so the test values are always valid. + * + * Note: glibc's get_nprocs_conf() returns the number of *configured* + * (present) CPUs, not *possible* CPUs. The kernel uses + * num_possible_cpus() which corresponds to /sys/devices/system/cpu/possible. + * These can differ significantly (e.g. 16 configured vs 128 possible). + */ +#define RESERVED_PIDS 300 +#define PIDS_PER_CPU_MIN 8 + +/* Count CPUs from a range list like "0-31" or "0-15,32-47". */ +static int num_possible_cpus(void) +{ + FILE *f; + int count = 0; + int lo, hi; + + f = fopen("/sys/devices/system/cpu/possible", "r"); + if (!f) + return 0; + + while (fscanf(f, "%d", &lo) == 1) { + if (fscanf(f, "-%d", &hi) == 1) + count += hi - lo + 1; + else + count++; + /* skip comma separator */ + fscanf(f, ","); + } + + fclose(f); + return count; +} + +static int pid_min(void) +{ + int cpu_min = PIDS_PER_CPU_MIN * num_possible_cpus(); + + return cpu_min > (RESERVED_PIDS + 1) ? cpu_min : (RESERVED_PIDS + 1); +} + +/* + * Outer and inner pid_max limits used by the tests. The outer limit is + * the more restrictive ancestor; the inner limit is set higher in a + * nested namespace but must still be capped by the outer limit. + * Both are derived from the kernel's minimum so they are always writable. + * + * Global so that clone callbacks can access them without parameter plumbing. + */ +static int outer_limit; +static int inner_limit; + +static int write_int_to_fd(int fd, int val) +{ + char buf[12]; + int len = snprintf(buf, sizeof(buf), "%d", val); + + return write(fd, buf, len); +} + #define __STACK_SIZE (8 * 1024 * 1024) static pid_t do_clone(int (*fn)(void *), void *arg, int flags) { @@ -60,18 +124,18 @@ static int pid_max_cb(void *data) return -1; } - ret = write(fd, "500", sizeof("500") - 1); + ret = write_int_to_fd(fd, inner_limit); if (ret < 0) { fprintf(stderr, "%m - Failed to write pid_max\n"); return -1; } - for (int i = 0; i < 501; i++) { + for (int i = 0; i < inner_limit + 1; i++) { pid = fork(); if (pid == 0) exit(EXIT_SUCCESS); wait_for_pid(pid); - if (pid > 500) { + if (pid > inner_limit) { fprintf(stderr, "Managed to create pid number beyond limit\n"); return -1; } @@ -106,7 +170,7 @@ static int pid_max_nested_inner(void *data) return fret; } - ret = write(fd, "500", sizeof("500") - 1); + ret = write_int_to_fd(fd, inner_limit); close(fd); if (ret < 0) { fprintf(stderr, "%m - Failed to write pid_max\n"); @@ -133,8 +197,8 @@ static int pid_max_nested_inner(void *data) return fret; } - /* Now make sure that we wrap pids at 400. */ - for (i = 0; i < 510; i++) { + /* Now make sure that we wrap pids at outer_limit. */ + for (i = 0; i < inner_limit + 10; i++) { pid_t pid; pid = fork(); @@ -145,7 +209,7 @@ static int pid_max_nested_inner(void *data) exit(EXIT_SUCCESS); wait_for_pid(pid); - if (pid >= 500) { + if (pid >= inner_limit) { fprintf(stderr, "Managed to create process with pid %d beyond configured limit\n", pid); return fret; } @@ -156,15 +220,19 @@ static int pid_max_nested_inner(void *data) static int pid_max_nested_outer(void *data) { - int fret = -1, nr_procs = 400; - pid_t pids[1000]; - int fd, i, ret; + int fret = -1, nr_procs = 0; + pid_t *pids; + int fd, ret; pid_t pid; + pids = malloc(outer_limit * sizeof(pid_t)); + if (!pids) + return -1; + ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0); if (ret) { fprintf(stderr, "%m - Failed to make rootfs private mount\n"); - return fret; + goto out; } umount2("/proc", MNT_DETACH); @@ -172,27 +240,28 @@ static int pid_max_nested_outer(void *data) ret = mount("proc", "/proc", "proc", 0, NULL); if (ret) { fprintf(stderr, "%m - Failed to mount proc\n"); - return fret; + goto out; } fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY); if (fd < 0) { fprintf(stderr, "%m - Failed to open pid_max\n"); - return fret; + goto out; } - ret = write(fd, "400", sizeof("400") - 1); + ret = write_int_to_fd(fd, outer_limit); close(fd); if (ret < 0) { fprintf(stderr, "%m - Failed to write pid_max\n"); - return fret; + goto out; } /* - * Create 397 processes. This leaves room for do_clone() (398) and - * one more 399. So creating another process needs to fail. + * Create (outer_limit - 4) processes. This leaves room for + * do_clone() and one more. So creating another process needs + * to fail. */ - for (nr_procs = 0; nr_procs < 396; nr_procs++) { + for (nr_procs = 0; nr_procs < outer_limit - 4; nr_procs++) { pid = fork(); if (pid < 0) goto reap; @@ -220,20 +289,26 @@ reap: for (int i = 0; i < nr_procs; i++) wait_for_pid(pids[i]); +out: + free(pids); return fret; } static int pid_max_nested_limit_inner(void *data) { - int fret = -1, nr_procs = 400; + int fret = -1, nr_procs = 0; int fd, ret; pid_t pid; - pid_t pids[1000]; + pid_t *pids; + + pids = malloc(inner_limit * sizeof(pid_t)); + if (!pids) + return -1; ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0); if (ret) { fprintf(stderr, "%m - Failed to make rootfs private mount\n"); - return fret; + goto out; } umount2("/proc", MNT_DETACH); @@ -241,23 +316,23 @@ static int pid_max_nested_limit_inner(void *data) ret = mount("proc", "/proc", "proc", 0, NULL); if (ret) { fprintf(stderr, "%m - Failed to mount proc\n"); - return fret; + goto out; } fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY); if (fd < 0) { fprintf(stderr, "%m - Failed to open pid_max\n"); - return fret; + goto out; } - ret = write(fd, "500", sizeof("500") - 1); + ret = write_int_to_fd(fd, inner_limit); close(fd); if (ret < 0) { fprintf(stderr, "%m - Failed to write pid_max\n"); - return fret; + goto out; } - for (nr_procs = 0; nr_procs < 500; nr_procs++) { + for (nr_procs = 0; nr_procs < inner_limit; nr_procs++) { pid = fork(); if (pid < 0) break; @@ -268,7 +343,7 @@ static int pid_max_nested_limit_inner(void *data) pids[nr_procs] = pid; } - if (nr_procs >= 400) { + if (nr_procs >= outer_limit) { fprintf(stderr, "Managed to create processes beyond the configured outer limit\n"); goto reap; } @@ -279,6 +354,8 @@ reap: for (int i = 0; i < nr_procs; i++) wait_for_pid(pids[i]); +out: + free(pids); return fret; } @@ -307,7 +384,7 @@ static int pid_max_nested_limit_outer(void *data) return -1; } - ret = write(fd, "400", sizeof("400") - 1); + ret = write_int_to_fd(fd, outer_limit); close(fd); if (ret < 0) { fprintf(stderr, "%m - Failed to write pid_max\n"); @@ -328,17 +405,32 @@ static int pid_max_nested_limit_outer(void *data) return 0; } -TEST(pid_max_simple) +FIXTURE(pid_max) { + int dummy; +}; + +FIXTURE_SETUP(pid_max) { - pid_t pid; + int min = pid_min(); + outer_limit = min + 100; + inner_limit = min + 200; +} + +FIXTURE_TEARDOWN(pid_max) +{ +} + +TEST_F(pid_max, simple) +{ + pid_t pid; pid = do_clone(pid_max_cb, NULL, CLONE_NEWPID | CLONE_NEWNS); ASSERT_GT(pid, 0); ASSERT_EQ(0, wait_for_pid(pid)); } -TEST(pid_max_nested_limit) +TEST_F(pid_max, nested_limit) { pid_t pid; @@ -347,7 +439,7 @@ TEST(pid_max_nested_limit) ASSERT_EQ(0, wait_for_pid(pid)); } -TEST(pid_max_nested) +TEST_F(pid_max, nested) { pid_t pid; diff --git a/tools/testing/selftests/pid_namespace/pidns_init_via_setns.c b/tools/testing/selftests/pid_namespace/pidns_init_via_setns.c new file mode 100644 index 000000000000..520835ca42ed --- /dev/null +++ b/tools/testing/selftests/pid_namespace/pidns_init_via_setns.c @@ -0,0 +1,238 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include <fcntl.h> +#include <sched.h> +#include <stdio.h> +#include <sys/types.h> +#include <unistd.h> + +#include "kselftest_harness.h" +#include "../pidfd/pidfd.h" + +/* + * Test that a process can become PID 1 (init) in a new PID namespace + * created via unshare() and joined via setns(). + * + * Flow: + * 1. Parent creates a pipe for synchronization. + * 2. Parent forks a child. + * 3. Parent calls unshare(CLONE_NEWPID) to create a new PID namespace. + * 4. Parent signals the child via the pipe. + * 5. Child opens parent's /proc/<ppid>/ns/pid_for_children and calls + * setns(fd, CLONE_NEWPID) to join the new namespace. + * 6. Child forks a grandchild. + * 7. Grandchild verifies getpid() == 1. + */ +TEST(pidns_init_via_setns) +{ + pid_t child, parent_pid; + int pipe_fd[2]; + char buf; + + if (geteuid()) + ASSERT_EQ(0, unshare(CLONE_NEWUSER)); + + parent_pid = getpid(); + + ASSERT_EQ(0, pipe(pipe_fd)); + + child = fork(); + ASSERT_GE(child, 0); + + if (child == 0) { + char path[256]; + int nsfd; + pid_t grandchild; + + close(pipe_fd[1]); + + /* Wait for parent to complete unshare */ + ASSERT_EQ(1, read_nointr(pipe_fd[0], &buf, 1)); + close(pipe_fd[0]); + + snprintf(path, sizeof(path), + "/proc/%d/ns/pid_for_children", parent_pid); + nsfd = open(path, O_RDONLY); + ASSERT_GE(nsfd, 0); + + ASSERT_EQ(0, setns(nsfd, CLONE_NEWPID)); + close(nsfd); + + grandchild = fork(); + ASSERT_GE(grandchild, 0); + + if (grandchild == 0) { + /* Should be init (PID 1) in the new namespace */ + if (getpid() != 1) + _exit(1); + _exit(0); + } + + ASSERT_EQ(0, wait_for_pid(grandchild)); + _exit(0); + } + + close(pipe_fd[0]); + + ASSERT_EQ(0, unshare(CLONE_NEWPID)); + + /* Signal child that the new PID namespace is ready */ + buf = 0; + ASSERT_EQ(1, write_nointr(pipe_fd[1], &buf, 1)); + close(pipe_fd[1]); + + ASSERT_EQ(0, wait_for_pid(child)); +} + +/* + * Similar to pidns_init_via_setns, but: + * 1. Parent enters a new PID namespace right from the start to be able to + * later freely use pid 1001 in it. + * 2. After forking child, parent also calls unshare(CLONE_NEWUSER) + * before unshare(CLONE_NEWPID) so that new old and new pid namespaces have + * different user namespace owners. + * 3. Child uses clone3() with set_tid={1, 1001} instead of fork() and + * grandchild checks that it gets desired pids . + * + * Flow: + * 1. Test process creates a new PID namespace and forks a wrapper + * (PID 1 in the outer namespace). + * 2. Wrapper forks a child. + * 3. Wrapper calls unshare(CLONE_NEWUSER) + unshare(CLONE_NEWPID) + * to create an inner PID namespace. + * 4. Wrapper signals the child via pipe. + * 5. Child opens wrapper's /proc/<pid>/ns/pid_for_children and calls + * setns(fd, CLONE_NEWPID) to join the inner namespace. + * 6. Child calls clone3() with set_tid={1, 1001}. + * 7. Grandchild verifies its NSpid ends with "1001 1". + */ + +pid_t set_tid[] = {1, 1001}; + +static int pidns_init_via_setns_set_tid_grandchild(struct __test_metadata *_metadata) +{ + char *line = NULL; + size_t len = 0; + int found = 0; + FILE *gf; + + gf = fopen("/proc/self/status", "r"); + ASSERT_NE(gf, NULL); + + while (getline(&line, &len, gf) != -1) { + if (strncmp(line, "NSpid:", 6) != 0) + continue; + + for (int i = 0; i < 2; i++) { + char *last = strrchr(line, '\t'); + pid_t pid; + + ASSERT_NE(last, NULL); + ASSERT_EQ(sscanf(last, "%d", &pid), 1); + ASSERT_EQ(pid, set_tid[i]); + *last = '\0'; + } + + found = true; + break; + } + + free(line); + fclose(gf); + ASSERT_TRUE(found); + return 0; +} + +static int pidns_init_via_setns_set_tid_child(struct __test_metadata *_metadata, + pid_t parent_pid, int pipe_fd[2]) +{ + struct __clone_args args = { + .exit_signal = SIGCHLD, + .set_tid = ptr_to_u64(set_tid), + .set_tid_size = 2, + }; + pid_t grandchild; + char path[256]; + char buf; + int nsfd; + + close(pipe_fd[1]); + + ASSERT_EQ(1, read_nointr(pipe_fd[0], &buf, 1)); + close(pipe_fd[0]); + + snprintf(path, sizeof(path), + "/proc/%d/ns/pid_for_children", parent_pid); + nsfd = open(path, O_RDONLY); + ASSERT_GE(nsfd, 0); + + ASSERT_EQ(0, setns(nsfd, CLONE_NEWPID)); + close(nsfd); + + grandchild = sys_clone3(&args, sizeof(args)); + ASSERT_GE(grandchild, 0); + + if (grandchild == 0) + _exit(pidns_init_via_setns_set_tid_grandchild(_metadata)); + + ASSERT_EQ(0, wait_for_pid(grandchild)); + return 0; +} + +static int pidns_init_via_setns_set_tid_wrapper(struct __test_metadata *_metadata) +{ + int pipe_fd[2]; + pid_t child, parent_pid; + char buf; + FILE *f; + + /* + * We are PID 1 inside the new namespace, but /proc is + * mounted from the host. Read our host-visible PID so + * the child can reach our pid_for_children via /proc. + */ + f = fopen("/proc/self/stat", "r"); + ASSERT_NE(f, NULL); + ASSERT_EQ(fscanf(f, "%d", &parent_pid), 1); + ASSERT_EQ(0, pipe(pipe_fd)); + + child = fork(); + ASSERT_GE(child, 0); + + if (child == 0) + _exit(pidns_init_via_setns_set_tid_child(_metadata, parent_pid, pipe_fd)); + + close(pipe_fd[0]); + + ASSERT_EQ(0, unshare(CLONE_NEWUSER)); + ASSERT_EQ(0, unshare(CLONE_NEWPID)); + + buf = 0; + ASSERT_EQ(1, write_nointr(pipe_fd[1], &buf, 1)); + close(pipe_fd[1]); + + ASSERT_EQ(0, wait_for_pid(child)); + + fclose(f); + return 0; +} + +TEST(pidns_init_via_setns_set_tid) +{ + pid_t wrapper; + + if (geteuid()) + SKIP(return, "This test needs root to run!"); + + ASSERT_EQ(0, unshare(CLONE_NEWPID)); + + wrapper = fork(); + ASSERT_GE(wrapper, 0); + + if (wrapper == 0) + _exit(pidns_init_via_setns_set_tid_wrapper(_metadata)); + + ASSERT_EQ(0, wait_for_pid(wrapper)); +} + +TEST_HARNESS_MAIN |