selftests/capabilities: Add tests for capability evolution
This test focuses on ambient capabilities. It requires either root or the ability to create user namespaces. Some of the test cases will be skipped for nonroot users. Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Cc: Christoph Lameter <cl@linux.com> # Original author Cc: Serge E. Hallyn <serge.hallyn@ubuntu.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Shuah Khan <shuahkh@osg.samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andy Lutomirski
Linus Torvalds
Родитель
58319057b7
Коммит
32ae976ed3
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@ -0,0 +1,2 @@
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test_execve
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validate_cap
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@ -0,0 +1,18 @@
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all:
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include ../lib.mk
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.PHONY: all clean
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TARGETS := validate_cap test_execve
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TEST_PROGS := test_execve
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CFLAGS := -O2 -g -std=gnu99 -Wall -lcap-ng
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all: $(TARGETS)
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clean:
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$(RM) $(TARGETS)
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$(TARGETS): %: %.c
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$(CC) -o $@ $(CFLAGS) $(EXTRA_CFLAGS) $^ -lrt -ldl
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@ -0,0 +1,427 @@
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#define _GNU_SOURCE
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#include <cap-ng.h>
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#include <err.h>
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#include <linux/capability.h>
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#include <stdbool.h>
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#include <string.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <stdarg.h>
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#include <sched.h>
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#include <sys/mount.h>
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#include <limits.h>
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#include <libgen.h>
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#include <malloc.h>
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#include <sys/wait.h>
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#include <sys/prctl.h>
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#include <sys/stat.h>
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#ifndef PR_CAP_AMBIENT
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#define PR_CAP_AMBIENT 47
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# define PR_CAP_AMBIENT_IS_SET 1
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# define PR_CAP_AMBIENT_RAISE 2
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# define PR_CAP_AMBIENT_LOWER 3
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# define PR_CAP_AMBIENT_CLEAR_ALL 4
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#endif
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static int nerrs;
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static void vmaybe_write_file(bool enoent_ok, char *filename, char *fmt, va_list ap)
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{
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char buf[4096];
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int fd;
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ssize_t written;
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int buf_len;
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buf_len = vsnprintf(buf, sizeof(buf), fmt, ap);
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if (buf_len < 0) {
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err(1, "vsnprintf failed");
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}
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if (buf_len >= sizeof(buf)) {
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errx(1, "vsnprintf output truncated");
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}
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fd = open(filename, O_WRONLY);
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if (fd < 0) {
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if ((errno == ENOENT) && enoent_ok)
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return;
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err(1, "open of %s failed", filename);
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}
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written = write(fd, buf, buf_len);
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if (written != buf_len) {
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if (written >= 0) {
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errx(1, "short write to %s", filename);
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} else {
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err(1, "write to %s failed", filename);
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}
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}
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if (close(fd) != 0) {
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err(1, "close of %s failed", filename);
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}
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}
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static void maybe_write_file(char *filename, char *fmt, ...)
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{
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va_list ap;
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va_start(ap, fmt);
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vmaybe_write_file(true, filename, fmt, ap);
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va_end(ap);
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}
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static void write_file(char *filename, char *fmt, ...)
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{
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va_list ap;
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va_start(ap, fmt);
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vmaybe_write_file(false, filename, fmt, ap);
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va_end(ap);
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}
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static bool create_and_enter_ns(uid_t inner_uid)
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{
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uid_t outer_uid;
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gid_t outer_gid;
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int i;
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bool have_outer_privilege;
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outer_uid = getuid();
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outer_gid = getgid();
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/*
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* TODO: If we're already root, we could skip creating the userns.
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*/
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if (unshare(CLONE_NEWNS) == 0) {
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printf("[NOTE]\tUsing global UIDs for tests\n");
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if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) != 0)
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err(1, "PR_SET_KEEPCAPS");
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if (setresuid(inner_uid, inner_uid, -1) != 0)
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err(1, "setresuid");
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// Re-enable effective caps
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capng_get_caps_process();
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for (i = 0; i < CAP_LAST_CAP; i++)
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if (capng_have_capability(CAPNG_PERMITTED, i))
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capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, i);
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if (capng_apply(CAPNG_SELECT_CAPS) != 0)
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err(1, "capng_apply");
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have_outer_privilege = true;
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} else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) {
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printf("[NOTE]\tUsing a user namespace for tests\n");
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maybe_write_file("/proc/self/setgroups", "deny");
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write_file("/proc/self/uid_map", "%d %d 1", inner_uid, outer_uid);
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write_file("/proc/self/gid_map", "0 %d 1", outer_gid);
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have_outer_privilege = false;
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} else {
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errx(1, "must be root or be able to create a userns");
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}
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if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL) != 0)
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err(1, "remount everything private");
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return have_outer_privilege;
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}
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static void chdir_to_tmpfs(void)
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{
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char cwd[PATH_MAX];
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if (getcwd(cwd, sizeof(cwd)) != cwd)
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err(1, "getcwd");
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if (mount("private_tmp", ".", "tmpfs", 0, "mode=0777") != 0)
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err(1, "mount private tmpfs");
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if (chdir(cwd) != 0)
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err(1, "chdir to private tmpfs");
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if (umount2(".", MNT_DETACH) != 0)
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err(1, "detach private tmpfs");
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}
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static void copy_fromat_to(int fromfd, const char *fromname, const char *toname)
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{
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int from = openat(fromfd, fromname, O_RDONLY);
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if (from == -1)
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err(1, "open copy source");
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int to = open(toname, O_CREAT | O_WRONLY | O_EXCL, 0700);
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while (true) {
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char buf[4096];
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ssize_t sz = read(from, buf, sizeof(buf));
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if (sz == 0)
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break;
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if (sz < 0)
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err(1, "read");
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if (write(to, buf, sz) != sz)
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err(1, "write"); /* no short writes on tmpfs */
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}
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close(from);
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close(to);
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}
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static bool fork_wait(void)
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{
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pid_t child = fork();
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if (child == 0) {
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nerrs = 0;
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return true;
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} else if (child > 0) {
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int status;
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if (waitpid(child, &status, 0) != child ||
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!WIFEXITED(status)) {
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printf("[FAIL]\tChild died\n");
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nerrs++;
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} else if (WEXITSTATUS(status) != 0) {
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printf("[FAIL]\tChild failed\n");
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nerrs++;
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} else {
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printf("[OK]\tChild succeeded\n");
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}
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return false;
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} else {
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err(1, "fork");
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}
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}
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static void exec_other_validate_cap(const char *name,
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bool eff, bool perm, bool inh, bool ambient)
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{
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execl(name, name, (eff ? "1" : "0"),
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(perm ? "1" : "0"), (inh ? "1" : "0"), (ambient ? "1" : "0"),
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NULL);
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err(1, "execl");
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}
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static void exec_validate_cap(bool eff, bool perm, bool inh, bool ambient)
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{
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exec_other_validate_cap("./validate_cap", eff, perm, inh, ambient);
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}
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static int do_tests(int uid, const char *our_path)
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{
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bool have_outer_privilege = create_and_enter_ns(uid);
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int ourpath_fd = open(our_path, O_RDONLY | O_DIRECTORY);
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if (ourpath_fd == -1)
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err(1, "open '%s'", our_path);
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chdir_to_tmpfs();
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copy_fromat_to(ourpath_fd, "validate_cap", "validate_cap");
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if (have_outer_privilege) {
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uid_t gid = getegid();
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copy_fromat_to(ourpath_fd, "validate_cap",
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"validate_cap_suidroot");
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if (chown("validate_cap_suidroot", 0, -1) != 0)
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err(1, "chown");
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if (chmod("validate_cap_suidroot", S_ISUID | 0700) != 0)
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err(1, "chmod");
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copy_fromat_to(ourpath_fd, "validate_cap",
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"validate_cap_suidnonroot");
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if (chown("validate_cap_suidnonroot", uid + 1, -1) != 0)
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err(1, "chown");
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if (chmod("validate_cap_suidnonroot", S_ISUID | 0700) != 0)
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err(1, "chmod");
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copy_fromat_to(ourpath_fd, "validate_cap",
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"validate_cap_sgidroot");
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if (chown("validate_cap_sgidroot", -1, 0) != 0)
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err(1, "chown");
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if (chmod("validate_cap_sgidroot", S_ISGID | 0710) != 0)
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err(1, "chmod");
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copy_fromat_to(ourpath_fd, "validate_cap",
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"validate_cap_sgidnonroot");
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if (chown("validate_cap_sgidnonroot", -1, gid + 1) != 0)
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err(1, "chown");
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if (chmod("validate_cap_sgidnonroot", S_ISGID | 0710) != 0)
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err(1, "chmod");
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}
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capng_get_caps_process();
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/* Make sure that i starts out clear */
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capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
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if (capng_apply(CAPNG_SELECT_CAPS) != 0)
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err(1, "capng_apply");
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if (uid == 0) {
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printf("[RUN]\tRoot => ep\n");
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if (fork_wait())
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exec_validate_cap(true, true, false, false);
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} else {
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printf("[RUN]\tNon-root => no caps\n");
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if (fork_wait())
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exec_validate_cap(false, false, false, false);
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}
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printf("[OK]\tCheck cap_ambient manipulation rules\n");
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/* We should not be able to add ambient caps yet. */
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if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != -1 || errno != EPERM) {
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if (errno == EINVAL)
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printf("[FAIL]\tPR_CAP_AMBIENT_RAISE isn't supported\n");
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else
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printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have failed eith EPERM on a non-inheritable cap\n");
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return 1;
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}
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printf("[OK]\tPR_CAP_AMBIENT_RAISE failed on non-inheritable cap\n");
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capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_RAW);
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capng_update(CAPNG_DROP, CAPNG_PERMITTED, CAP_NET_RAW);
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capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_NET_RAW);
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if (capng_apply(CAPNG_SELECT_CAPS) != 0)
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err(1, "capng_apply");
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if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_RAW, 0, 0, 0) != -1 || errno != EPERM) {
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printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have failed on a non-permitted cap\n");
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return 1;
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}
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printf("[OK]\tPR_CAP_AMBIENT_RAISE failed on non-permitted cap\n");
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capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
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if (capng_apply(CAPNG_SELECT_CAPS) != 0)
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err(1, "capng_apply");
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if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
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printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have succeeded\n");
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return 1;
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}
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printf("[OK]\tPR_CAP_AMBIENT_RAISE worked\n");
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if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 1) {
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printf("[FAIL]\tPR_CAP_AMBIENT_IS_SET is broken\n");
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return 1;
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}
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if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0, 0) != 0)
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err(1, "PR_CAP_AMBIENT_CLEAR_ALL");
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if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
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printf("[FAIL]\tPR_CAP_AMBIENT_CLEAR_ALL didn't work\n");
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return 1;
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}
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|
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if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
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err(1, "PR_CAP_AMBIENT_RAISE");
|
||||
|
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capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
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if (capng_apply(CAPNG_SELECT_CAPS) != 0)
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err(1, "capng_apply");
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if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
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printf("[FAIL]\tDropping I should have dropped A\n");
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return 1;
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}
|
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printf("[OK]\tBasic manipulation appears to work\n");
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|
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capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
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if (capng_apply(CAPNG_SELECT_CAPS) != 0)
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err(1, "capng_apply");
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if (uid == 0) {
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printf("[RUN]\tRoot +i => eip\n");
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if (fork_wait())
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exec_validate_cap(true, true, true, false);
|
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} else {
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printf("[RUN]\tNon-root +i => i\n");
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if (fork_wait())
|
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exec_validate_cap(false, false, true, false);
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}
|
||||
|
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if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
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err(1, "PR_CAP_AMBIENT_RAISE");
|
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|
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printf("[RUN]\tUID %d +ia => eipa\n", uid);
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if (fork_wait())
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exec_validate_cap(true, true, true, true);
|
||||
|
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/* The remaining tests need real privilege */
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|
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if (!have_outer_privilege) {
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printf("[SKIP]\tSUID/SGID tests (needs privilege)\n");
|
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goto done;
|
||||
}
|
||||
|
||||
if (uid == 0) {
|
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printf("[RUN]\tRoot +ia, suidroot => eipa\n");
|
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if (fork_wait())
|
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exec_other_validate_cap("./validate_cap_suidroot",
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true, true, true, true);
|
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|
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printf("[RUN]\tRoot +ia, suidnonroot => ip\n");
|
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if (fork_wait())
|
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exec_other_validate_cap("./validate_cap_suidnonroot",
|
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false, true, true, false);
|
||||
|
||||
printf("[RUN]\tRoot +ia, sgidroot => eipa\n");
|
||||
if (fork_wait())
|
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exec_other_validate_cap("./validate_cap_sgidroot",
|
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true, true, true, true);
|
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|
||||
if (fork_wait()) {
|
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printf("[RUN]\tRoot, gid != 0, +ia, sgidroot => eip\n");
|
||||
if (setresgid(1, 1, 1) != 0)
|
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err(1, "setresgid");
|
||||
exec_other_validate_cap("./validate_cap_sgidroot",
|
||||
true, true, true, false);
|
||||
}
|
||||
|
||||
printf("[RUN]\tRoot +ia, sgidnonroot => eip\n");
|
||||
if (fork_wait())
|
||||
exec_other_validate_cap("./validate_cap_sgidnonroot",
|
||||
true, true, true, false);
|
||||
} else {
|
||||
printf("[RUN]\tNon-root +ia, sgidnonroot => i\n");
|
||||
exec_other_validate_cap("./validate_cap_sgidnonroot",
|
||||
false, false, true, false);
|
||||
|
||||
if (fork_wait()) {
|
||||
printf("[RUN]\tNon-root +ia, sgidroot => i\n");
|
||||
if (setresgid(1, 1, 1) != 0)
|
||||
err(1, "setresgid");
|
||||
exec_other_validate_cap("./validate_cap_sgidroot",
|
||||
false, false, true, false);
|
||||
}
|
||||
}
|
||||
|
||||
done:
|
||||
return nerrs ? 1 : 0;
|
||||
}
|
||||
|
||||
int main(int argc, char **argv)
|
||||
{
|
||||
char *tmp1, *tmp2, *our_path;
|
||||
|
||||
/* Find our path */
|
||||
tmp1 = strdup(argv[0]);
|
||||
if (!tmp1)
|
||||
err(1, "strdup");
|
||||
tmp2 = dirname(tmp1);
|
||||
our_path = strdup(tmp2);
|
||||
if (!our_path)
|
||||
err(1, "strdup");
|
||||
free(tmp1);
|
||||
|
||||
if (fork_wait()) {
|
||||
printf("[RUN]\t+++ Tests with uid == 0 +++\n");
|
||||
return do_tests(0, our_path);
|
||||
}
|
||||
|
||||
if (fork_wait()) {
|
||||
printf("[RUN]\t+++ Tests with uid != 0 +++\n");
|
||||
return do_tests(1, our_path);
|
||||
}
|
||||
|
||||
return nerrs ? 1 : 0;
|
||||
}
|
||||
|
|
@ -0,0 +1,73 @@
|
|||
#include <cap-ng.h>
|
||||
#include <err.h>
|
||||
#include <linux/capability.h>
|
||||
#include <stdbool.h>
|
||||
#include <string.h>
|
||||
#include <stdio.h>
|
||||
#include <sys/prctl.h>
|
||||
#include <sys/auxv.h>
|
||||
|
||||
#ifndef PR_CAP_AMBIENT
|
||||
#define PR_CAP_AMBIENT 47
|
||||
# define PR_CAP_AMBIENT_IS_SET 1
|
||||
# define PR_CAP_AMBIENT_RAISE 2
|
||||
# define PR_CAP_AMBIENT_LOWER 3
|
||||
# define PR_CAP_AMBIENT_CLEAR_ALL 4
|
||||
#endif
|
||||
|
||||
#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 19)
|
||||
# define HAVE_GETAUXVAL
|
||||
#endif
|
||||
|
||||
static bool bool_arg(char **argv, int i)
|
||||
{
|
||||
if (!strcmp(argv[i], "0"))
|
||||
return false;
|
||||
else if (!strcmp(argv[i], "1"))
|
||||
return true;
|
||||
else
|
||||
errx(1, "wrong argv[%d]", i);
|
||||
}
|
||||
|
||||
int main(int argc, char **argv)
|
||||
{
|
||||
const char *atsec = "";
|
||||
|
||||
/*
|
||||
* Be careful just in case a setgid or setcapped copy of this
|
||||
* helper gets out.
|
||||
*/
|
||||
|
||||
if (argc != 5)
|
||||
errx(1, "wrong argc");
|
||||
|
||||
#ifdef HAVE_GETAUXVAL
|
||||
if (getauxval(AT_SECURE))
|
||||
atsec = " (AT_SECURE is set)";
|
||||
else
|
||||
atsec = " (AT_SECURE is not set)";
|
||||
#endif
|
||||
|
||||
capng_get_caps_process();
|
||||
|
||||
if (capng_have_capability(CAPNG_EFFECTIVE, CAP_NET_BIND_SERVICE) != bool_arg(argv, 1)) {
|
||||
printf("[FAIL]\tWrong effective state%s\n", atsec);
|
||||
return 1;
|
||||
}
|
||||
if (capng_have_capability(CAPNG_PERMITTED, CAP_NET_BIND_SERVICE) != bool_arg(argv, 2)) {
|
||||
printf("[FAIL]\tWrong permitted state%s\n", atsec);
|
||||
return 1;
|
||||
}
|
||||
if (capng_have_capability(CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE) != bool_arg(argv, 3)) {
|
||||
printf("[FAIL]\tWrong inheritable state%s\n", atsec);
|
||||
return 1;
|
||||
}
|
||||
|
||||
if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != bool_arg(argv, 4)) {
|
||||
printf("[FAIL]\tWrong ambient state%s\n", atsec);
|
||||
return 1;
|
||||
}
|
||||
|
||||
printf("[OK]\tCapabilities after execve were correct\n");
|
||||
return 0;
|
||||
}
|
||||
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