diff options
Diffstat (limited to 'tools/testing/selftests/capabilities/test_execve.c')
| -rw-r--r-- | tools/testing/selftests/capabilities/test_execve.c | 427 |
1 files changed, 427 insertions, 0 deletions
diff --git a/tools/testing/selftests/capabilities/test_execve.c b/tools/testing/selftests/capabilities/test_execve.c new file mode 100644 index 000000000000..10a21a958aaf --- /dev/null +++ b/tools/testing/selftests/capabilities/test_execve.c @@ -0,0 +1,427 @@ +#define _GNU_SOURCE + +#include <cap-ng.h> +#include <err.h> +#include <linux/capability.h> +#include <stdbool.h> +#include <string.h> +#include <stdio.h> +#include <fcntl.h> +#include <errno.h> +#include <stdarg.h> +#include <sched.h> +#include <sys/mount.h> +#include <limits.h> +#include <libgen.h> +#include <malloc.h> +#include <sys/wait.h> +#include <sys/prctl.h> +#include <sys/stat.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 + +static int nerrs; + +static void vmaybe_write_file(bool enoent_ok, char *filename, char *fmt, va_list ap) +{ + char buf[4096]; + int fd; + ssize_t written; + int buf_len; + + buf_len = vsnprintf(buf, sizeof(buf), fmt, ap); + if (buf_len < 0) { + err(1, "vsnprintf failed"); + } + if (buf_len >= sizeof(buf)) { + errx(1, "vsnprintf output truncated"); + } + + fd = open(filename, O_WRONLY); + if (fd < 0) { + if ((errno == ENOENT) && enoent_ok) + return; + err(1, "open of %s failed", filename); + } + written = write(fd, buf, buf_len); + if (written != buf_len) { + if (written >= 0) { + errx(1, "short write to %s", filename); + } else { + err(1, "write to %s failed", filename); + } + } + if (close(fd) != 0) { + err(1, "close of %s failed", filename); + } +} + +static void maybe_write_file(char *filename, char *fmt, ...) +{ + va_list ap; + + va_start(ap, fmt); + vmaybe_write_file(true, filename, fmt, ap); + va_end(ap); +} + +static void write_file(char *filename, char *fmt, ...) +{ + va_list ap; + + va_start(ap, fmt); + vmaybe_write_file(false, filename, fmt, ap); + va_end(ap); +} + +static bool create_and_enter_ns(uid_t inner_uid) +{ + uid_t outer_uid; + gid_t outer_gid; + int i; + bool have_outer_privilege; + + outer_uid = getuid(); + outer_gid = getgid(); + + /* + * TODO: If we're already root, we could skip creating the userns. + */ + + if (unshare(CLONE_NEWNS) == 0) { + printf("[NOTE]\tUsing global UIDs for tests\n"); + if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) != 0) + err(1, "PR_SET_KEEPCAPS"); + if (setresuid(inner_uid, inner_uid, -1) != 0) + err(1, "setresuid"); + + // Re-enable effective caps + capng_get_caps_process(); + for (i = 0; i < CAP_LAST_CAP; i++) + if (capng_have_capability(CAPNG_PERMITTED, i)) + capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, i); + if (capng_apply(CAPNG_SELECT_CAPS) != 0) + err(1, "capng_apply"); + + have_outer_privilege = true; + } else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) { + printf("[NOTE]\tUsing a user namespace for tests\n"); + maybe_write_file("/proc/self/setgroups", "deny"); + write_file("/proc/self/uid_map", "%d %d 1", inner_uid, outer_uid); + write_file("/proc/self/gid_map", "0 %d 1", outer_gid); + + have_outer_privilege = false; + } else { + errx(1, "must be root or be able to create a userns"); + } + + if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL) != 0) + err(1, "remount everything private"); + + return have_outer_privilege; +} + +static void chdir_to_tmpfs(void) +{ + char cwd[PATH_MAX]; + if (getcwd(cwd, sizeof(cwd)) != cwd) + err(1, "getcwd"); + + if (mount("private_tmp", ".", "tmpfs", 0, "mode=0777") != 0) + err(1, "mount private tmpfs"); + + if (chdir(cwd) != 0) + err(1, "chdir to private tmpfs"); + + if (umount2(".", MNT_DETACH) != 0) + err(1, "detach private tmpfs"); +} + +static void copy_fromat_to(int fromfd, const char *fromname, const char *toname) +{ + int from = openat(fromfd, fromname, O_RDONLY); + if (from == -1) + err(1, "open copy source"); + + int to = open(toname, O_CREAT | O_WRONLY | O_EXCL, 0700); + + while (true) { + char buf[4096]; + ssize_t sz = read(from, buf, sizeof(buf)); + if (sz == 0) + break; + if (sz < 0) + err(1, "read"); + + if (write(to, buf, sz) != sz) + err(1, "write"); /* no short writes on tmpfs */ + } + + close(from); + close(to); +} + +static bool fork_wait(void) +{ + pid_t child = fork(); + if (child == 0) { + nerrs = 0; + return true; + } else if (child > 0) { + int status; + if (waitpid(child, &status, 0) != child || + !WIFEXITED(status)) { + printf("[FAIL]\tChild died\n"); + nerrs++; + } else if (WEXITSTATUS(status) != 0) { + printf("[FAIL]\tChild failed\n"); + nerrs++; + } else { + printf("[OK]\tChild succeeded\n"); + } + + return false; + } else { + err(1, "fork"); + } +} + +static void exec_other_validate_cap(const char *name, + bool eff, bool perm, bool inh, bool ambient) +{ + execl(name, name, (eff ? "1" : "0"), + (perm ? "1" : "0"), (inh ? "1" : "0"), (ambient ? "1" : "0"), + NULL); + err(1, "execl"); +} + +static void exec_validate_cap(bool eff, bool perm, bool inh, bool ambient) +{ + exec_other_validate_cap("./validate_cap", eff, perm, inh, ambient); +} + +static int do_tests(int uid, const char *our_path) +{ + bool have_outer_privilege = create_and_enter_ns(uid); + + int ourpath_fd = open(our_path, O_RDONLY | O_DIRECTORY); + if (ourpath_fd == -1) + err(1, "open '%s'", our_path); + + chdir_to_tmpfs(); + + copy_fromat_to(ourpath_fd, "validate_cap", "validate_cap"); + + if (have_outer_privilege) { + uid_t gid = getegid(); + + copy_fromat_to(ourpath_fd, "validate_cap", + "validate_cap_suidroot"); + if (chown("validate_cap_suidroot", 0, -1) != 0) + err(1, "chown"); + if (chmod("validate_cap_suidroot", S_ISUID | 0700) != 0) + err(1, "chmod"); + + copy_fromat_to(ourpath_fd, "validate_cap", + "validate_cap_suidnonroot"); + if (chown("validate_cap_suidnonroot", uid + 1, -1) != 0) + err(1, "chown"); + if (chmod("validate_cap_suidnonroot", S_ISUID | 0700) != 0) + err(1, "chmod"); + + copy_fromat_to(ourpath_fd, "validate_cap", + "validate_cap_sgidroot"); + if (chown("validate_cap_sgidroot", -1, 0) != 0) + err(1, "chown"); + if (chmod("validate_cap_sgidroot", S_ISGID | 0710) != 0) + err(1, "chmod"); + + copy_fromat_to(ourpath_fd, "validate_cap", + "validate_cap_sgidnonroot"); + if (chown("validate_cap_sgidnonroot", -1, gid + 1) != 0) + err(1, "chown"); + if (chmod("validate_cap_sgidnonroot", S_ISGID | 0710) != 0) + err(1, "chmod"); +} + + capng_get_caps_process(); + + /* Make sure that i starts out clear */ + capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE); + if (capng_apply(CAPNG_SELECT_CAPS) != 0) + err(1, "capng_apply"); + + if (uid == 0) { + printf("[RUN]\tRoot => ep\n"); + if (fork_wait()) + exec_validate_cap(true, true, false, false); + } else { + printf("[RUN]\tNon-root => no caps\n"); + if (fork_wait()) + exec_validate_cap(false, false, false, false); + } + + printf("[OK]\tCheck cap_ambient manipulation rules\n"); + + /* We should not be able to add ambient caps yet. */ + if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != -1 || errno != EPERM) { + if (errno == EINVAL) + printf("[FAIL]\tPR_CAP_AMBIENT_RAISE isn't supported\n"); + else + printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have failed eith EPERM on a non-inheritable cap\n"); + return 1; + } + printf("[OK]\tPR_CAP_AMBIENT_RAISE failed on non-inheritable cap\n"); + + capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_RAW); + capng_update(CAPNG_DROP, CAPNG_PERMITTED, CAP_NET_RAW); + capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_NET_RAW); + if (capng_apply(CAPNG_SELECT_CAPS) != 0) + err(1, "capng_apply"); + if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_RAW, 0, 0, 0) != -1 || errno != EPERM) { + printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have failed on a non-permitted cap\n"); + return 1; + } + printf("[OK]\tPR_CAP_AMBIENT_RAISE failed on non-permitted cap\n"); + + capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE); + if (capng_apply(CAPNG_SELECT_CAPS) != 0) + err(1, "capng_apply"); + if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) { + printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have succeeded\n"); + return 1; + } + printf("[OK]\tPR_CAP_AMBIENT_RAISE worked\n"); + + if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 1) { + printf("[FAIL]\tPR_CAP_AMBIENT_IS_SET is broken\n"); + return 1; + } + + if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0, 0) != 0) + err(1, "PR_CAP_AMBIENT_CLEAR_ALL"); + + if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) { + printf("[FAIL]\tPR_CAP_AMBIENT_CLEAR_ALL didn't work\n"); + return 1; + } + + if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) + err(1, "PR_CAP_AMBIENT_RAISE"); + + capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE); + if (capng_apply(CAPNG_SELECT_CAPS) != 0) + err(1, "capng_apply"); + + if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) { + printf("[FAIL]\tDropping I should have dropped A\n"); + return 1; + } + + printf("[OK]\tBasic manipulation appears to work\n"); + + capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE); + if (capng_apply(CAPNG_SELECT_CAPS) != 0) + err(1, "capng_apply"); + if (uid == 0) { + printf("[RUN]\tRoot +i => eip\n"); + if (fork_wait()) + exec_validate_cap(true, true, true, false); + } else { + printf("[RUN]\tNon-root +i => i\n"); + if (fork_wait()) + exec_validate_cap(false, false, true, false); + } + + if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) + err(1, "PR_CAP_AMBIENT_RAISE"); + + printf("[RUN]\tUID %d +ia => eipa\n", uid); + if (fork_wait()) + exec_validate_cap(true, true, true, true); + + /* The remaining tests need real privilege */ + + if (!have_outer_privilege) { + printf("[SKIP]\tSUID/SGID tests (needs privilege)\n"); + goto done; + } + + if (uid == 0) { + printf("[RUN]\tRoot +ia, suidroot => eipa\n"); + if (fork_wait()) + exec_other_validate_cap("./validate_cap_suidroot", + true, true, true, true); + + printf("[RUN]\tRoot +ia, suidnonroot => ip\n"); + if (fork_wait()) + exec_other_validate_cap("./validate_cap_suidnonroot", + false, true, true, false); + + printf("[RUN]\tRoot +ia, sgidroot => eipa\n"); + if (fork_wait()) + exec_other_validate_cap("./validate_cap_sgidroot", + true, true, true, true); + + if (fork_wait()) { + printf("[RUN]\tRoot, gid != 0, +ia, sgidroot => eip\n"); + if (setresgid(1, 1, 1) != 0) + 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; +} |