| #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"); |
| } |
| |
| 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; |
| } |