diff options
Diffstat (limited to 'src/core/execute.c')
-rw-r--r-- | src/core/execute.c | 1007 |
1 files changed, 736 insertions, 271 deletions
diff --git a/src/core/execute.c b/src/core/execute.c index 6019df7ea6..85ee82c3e1 100644 --- a/src/core/execute.c +++ b/src/core/execute.c @@ -29,8 +29,10 @@ #include <sys/mman.h> #include <sys/personality.h> #include <sys/prctl.h> +#include <sys/shm.h> #include <sys/socket.h> #include <sys/stat.h> +#include <sys/types.h> #include <sys/un.h> #include <unistd.h> #include <utmpx.h> @@ -91,6 +93,7 @@ #include "selinux-util.h" #include "signal-util.h" #include "smack-util.h" +#include "special.h" #include "string-table.h" #include "string-util.h" #include "strv.h" @@ -410,7 +413,8 @@ static int fixup_output(ExecOutput std_output, int socket_fd) { static int setup_input( const ExecContext *context, const ExecParameters *params, - int socket_fd) { + int socket_fd, + int named_iofds[3]) { ExecInput i; @@ -460,6 +464,10 @@ static int setup_input( case EXEC_INPUT_SOCKET: return dup2(socket_fd, STDIN_FILENO) < 0 ? -errno : STDIN_FILENO; + case EXEC_INPUT_NAMED_FD: + (void) fd_nonblock(named_iofds[STDIN_FILENO], false); + return dup2(named_iofds[STDIN_FILENO], STDIN_FILENO) < 0 ? -errno : STDIN_FILENO; + default: assert_not_reached("Unknown input type"); } @@ -471,6 +479,7 @@ static int setup_output( const ExecParameters *params, int fileno, int socket_fd, + int named_iofds[3], const char *ident, uid_t uid, gid_t gid, @@ -522,7 +531,7 @@ static int setup_output( return fileno; /* Duplicate from stdout if possible */ - if (e == o || e == EXEC_OUTPUT_INHERIT) + if ((e == o && e != EXEC_OUTPUT_NAMED_FD) || e == EXEC_OUTPUT_INHERIT) return dup2(STDOUT_FILENO, fileno) < 0 ? -errno : fileno; o = e; @@ -584,6 +593,10 @@ static int setup_output( assert(socket_fd >= 0); return dup2(socket_fd, fileno) < 0 ? -errno : fileno; + case EXEC_OUTPUT_NAMED_FD: + (void) fd_nonblock(named_iofds[fileno], false); + return dup2(named_iofds[fileno], fileno) < 0 ? -errno : fileno; + default: assert_not_reached("Unknown error type"); } @@ -719,73 +732,157 @@ static int ask_for_confirmation(char *response, char **argv) { return r; } -static int enforce_groups(const ExecContext *context, const char *username, gid_t gid) { - bool keep_groups = false; +static int get_fixed_user(const ExecContext *c, const char **user, + uid_t *uid, gid_t *gid, + const char **home, const char **shell) { int r; + const char *name; - assert(context); + assert(c); + + if (!c->user) + return 0; + + /* Note that we don't set $HOME or $SHELL if they are not particularly enlightening anyway + * (i.e. are "/" or "/bin/nologin"). */ + + name = c->user; + r = get_user_creds_clean(&name, uid, gid, home, shell); + if (r < 0) + return r; - /* Lookup and set GID and supplementary group list. Here too - * we avoid NSS lookups for gid=0. */ + *user = name; + return 0; +} - if (context->group || username) { +static int get_fixed_group(const ExecContext *c, const char **group, gid_t *gid) { + int r; + const char *name; + + assert(c); + + if (!c->group) + return 0; + + name = c->group; + r = get_group_creds(&name, gid); + if (r < 0) + return r; + + *group = name; + return 0; +} + +static int get_supplementary_groups(const ExecContext *c, const char *user, + const char *group, gid_t gid, + gid_t **supplementary_gids, int *ngids) { + char **i; + int r, k = 0; + int ngroups_max; + bool keep_groups = false; + gid_t *groups = NULL; + _cleanup_free_ gid_t *l_gids = NULL; + + assert(c); + + /* + * If user is given, then lookup GID and supplementary groups list. + * We avoid NSS lookups for gid=0. Also we have to initialize groups + * here and as early as possible so we keep the list of supplementary + * groups of the caller. + */ + if (user && gid_is_valid(gid) && gid != 0) { /* First step, initialize groups from /etc/groups */ - if (username && gid != 0) { - if (initgroups(username, gid) < 0) - return -errno; + if (initgroups(user, gid) < 0) + return -errno; - keep_groups = true; - } + keep_groups = true; + } - /* Second step, set our gids */ - if (setresgid(gid, gid, gid) < 0) + if (!c->supplementary_groups) + return 0; + + /* + * If SupplementaryGroups= was passed then NGROUPS_MAX has to + * be positive, otherwise fail. + */ + errno = 0; + ngroups_max = (int) sysconf(_SC_NGROUPS_MAX); + if (ngroups_max <= 0) { + if (errno > 0) return -errno; + else + return -EOPNOTSUPP; /* For all other values */ } - if (context->supplementary_groups) { - int ngroups_max, k; - gid_t *gids; - char **i; + l_gids = new(gid_t, ngroups_max); + if (!l_gids) + return -ENOMEM; - /* Final step, initialize any manually set supplementary groups */ - assert_se((ngroups_max = (int) sysconf(_SC_NGROUPS_MAX)) > 0); + if (keep_groups) { + /* + * Lookup the list of groups that the user belongs to, we + * avoid NSS lookups here too for gid=0. + */ + k = ngroups_max; + if (getgrouplist(user, gid, l_gids, &k) < 0) + return -EINVAL; + } else + k = 0; - if (!(gids = new(gid_t, ngroups_max))) - return -ENOMEM; + STRV_FOREACH(i, c->supplementary_groups) { + const char *g; - if (keep_groups) { - k = getgroups(ngroups_max, gids); - if (k < 0) { - free(gids); - return -errno; - } - } else - k = 0; + if (k >= ngroups_max) + return -E2BIG; - STRV_FOREACH(i, context->supplementary_groups) { - const char *g; + g = *i; + r = get_group_creds(&g, l_gids+k); + if (r < 0) + return r; - if (k >= ngroups_max) { - free(gids); - return -E2BIG; - } + k++; + } - g = *i; - r = get_group_creds(&g, gids+k); - if (r < 0) { - free(gids); - return r; - } + /* + * Sets ngids to zero to drop all supplementary groups, happens + * when we are under root and SupplementaryGroups= is empty. + */ + if (k == 0) { + *ngids = 0; + return 0; + } - k++; - } + /* Otherwise get the final list of supplementary groups */ + groups = memdup(l_gids, sizeof(gid_t) * k); + if (!groups) + return -ENOMEM; - if (setgroups(k, gids) < 0) { - free(gids); - return -errno; - } + *supplementary_gids = groups; + *ngids = k; + + groups = NULL; + + return 0; +} + +static int enforce_groups(const ExecContext *context, gid_t gid, + gid_t *supplementary_gids, int ngids) { + int r; - free(gids); + assert(context); + + /* Handle SupplementaryGroups= even if it is empty */ + if (context->supplementary_groups) { + r = maybe_setgroups(ngids, supplementary_gids); + if (r < 0) + return r; + } + + if (gid_is_valid(gid)) { + /* Then set our gids */ + if (setresgid(gid, gid, gid) < 0) + return -errno; } return 0; @@ -794,6 +891,9 @@ static int enforce_groups(const ExecContext *context, const char *username, gid_ static int enforce_user(const ExecContext *context, uid_t uid) { assert(context); + if (!uid_is_valid(uid)) + return 0; + /* Sets (but doesn't look up) the uid and make sure we keep the * capabilities while doing so. */ @@ -836,14 +936,19 @@ static int null_conv( return PAM_CONV_ERR; } +#endif + static int setup_pam( const char *name, const char *user, uid_t uid, + gid_t gid, const char *tty, char ***env, int fds[], unsigned n_fds) { +#ifdef HAVE_PAM + static const struct pam_conv conv = { .conv = null_conv, .appdata_ptr = NULL @@ -943,8 +1048,14 @@ static int setup_pam( * and this will make PR_SET_PDEATHSIG work in most cases. * If this fails, ignore the error - but expect sd-pam threads * to fail to exit normally */ + + r = maybe_setgroups(0, NULL); + if (r < 0) + log_warning_errno(r, "Failed to setgroups() in sd-pam: %m"); + if (setresgid(gid, gid, gid) < 0) + log_warning_errno(errno, "Failed to setresgid() in sd-pam: %m"); if (setresuid(uid, uid, uid) < 0) - log_error_errno(r, "Error: Failed to setresuid() in sd-pam: %m"); + log_warning_errno(errno, "Failed to setresuid() in sd-pam: %m"); (void) ignore_signals(SIGPIPE, -1); @@ -1037,8 +1148,10 @@ fail: closelog(); return r; -} +#else + return 0; #endif +} static void rename_process_from_path(const char *path) { char process_name[11]; @@ -1073,15 +1186,29 @@ static void rename_process_from_path(const char *path) { #ifdef HAVE_SECCOMP -static int apply_seccomp(const ExecContext *c) { +static bool skip_seccomp_unavailable(const Unit* u, const char* msg) { + + if (is_seccomp_available()) + return false; + + log_open(); + log_unit_debug(u, "SECCOMP features not detected in the kernel, skipping %s", msg); + log_close(); + return true; +} + +static int apply_seccomp(const Unit* u, const ExecContext *c) { uint32_t negative_action, action; - scmp_filter_ctx *seccomp; + scmp_filter_ctx seccomp; Iterator i; void *id; int r; assert(c); + if (skip_seccomp_unavailable(u, "syscall filtering")) + return 0; + negative_action = c->syscall_errno == 0 ? SCMP_ACT_KILL : SCMP_ACT_ERRNO(c->syscall_errno); seccomp = seccomp_init(c->syscall_whitelist ? negative_action : SCMP_ACT_ALLOW); @@ -1122,20 +1249,23 @@ finish: return r; } -static int apply_address_families(const ExecContext *c) { - scmp_filter_ctx *seccomp; +static int apply_address_families(const Unit* u, const ExecContext *c) { + scmp_filter_ctx seccomp; Iterator i; int r; +#if defined(__i386__) + return 0; +#endif + assert(c); - seccomp = seccomp_init(SCMP_ACT_ALLOW); - if (!seccomp) - return -ENOMEM; + if (skip_seccomp_unavailable(u, "RestrictAddressFamilies=")) + return 0; - r = seccomp_add_secondary_archs(seccomp); + r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW); if (r < 0) - goto finish; + return r; if (c->address_families_whitelist) { int af, first = 0, last = 0; @@ -1232,10 +1362,6 @@ static int apply_address_families(const ExecContext *c) { } } - r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0); - if (r < 0) - goto finish; - r = seccomp_load(seccomp); finish: @@ -1243,15 +1369,18 @@ finish: return r; } -static int apply_memory_deny_write_execute(const ExecContext *c) { - scmp_filter_ctx *seccomp; +static int apply_memory_deny_write_execute(const Unit* u, const ExecContext *c) { + scmp_filter_ctx seccomp; int r; assert(c); - seccomp = seccomp_init(SCMP_ACT_ALLOW); - if (!seccomp) - return -ENOMEM; + if (skip_seccomp_unavailable(u, "MemoryDenyWriteExecute=")) + return 0; + + r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW); + if (r < 0) + return r; r = seccomp_rule_add( seccomp, @@ -1271,7 +1400,12 @@ static int apply_memory_deny_write_execute(const ExecContext *c) { if (r < 0) goto finish; - r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0); + r = seccomp_rule_add( + seccomp, + SCMP_ACT_ERRNO(EPERM), + SCMP_SYS(shmat), + 1, + SCMP_A2(SCMP_CMP_MASKED_EQ, SHM_EXEC, SHM_EXEC)); if (r < 0) goto finish; @@ -1282,22 +1416,25 @@ finish: return r; } -static int apply_restrict_realtime(const ExecContext *c) { +static int apply_restrict_realtime(const Unit* u, const ExecContext *c) { static const int permitted_policies[] = { SCHED_OTHER, SCHED_BATCH, SCHED_IDLE, }; - scmp_filter_ctx *seccomp; + scmp_filter_ctx seccomp; unsigned i; int r, p, max_policy = 0; assert(c); - seccomp = seccomp_init(SCMP_ACT_ALLOW); - if (!seccomp) - return -ENOMEM; + if (skip_seccomp_unavailable(u, "RestrictRealtime=")) + return 0; + + r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW); + if (r < 0) + return r; /* Determine the highest policy constant we want to allow */ for (i = 0; i < ELEMENTSOF(permitted_policies); i++) @@ -1341,7 +1478,34 @@ static int apply_restrict_realtime(const ExecContext *c) { if (r < 0) goto finish; - r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0); + r = seccomp_load(seccomp); + +finish: + seccomp_release(seccomp); + return r; +} + +static int apply_protect_sysctl(const Unit *u, const ExecContext *c) { + scmp_filter_ctx seccomp; + int r; + + assert(c); + + /* Turn off the legacy sysctl() system call. Many distributions turn this off while building the kernel, but + * let's protect even those systems where this is left on in the kernel. */ + + if (skip_seccomp_unavailable(u, "ProtectKernelTunables=")) + return 0; + + r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW); + if (r < 0) + return r; + + r = seccomp_rule_add( + seccomp, + SCMP_ACT_ERRNO(EPERM), + SCMP_SYS(_sysctl), + 0); if (r < 0) goto finish; @@ -1352,12 +1516,33 @@ finish: return r; } +static int apply_protect_kernel_modules(const Unit *u, const ExecContext *c) { + assert(c); + + /* Turn off module syscalls on ProtectKernelModules=yes */ + + if (skip_seccomp_unavailable(u, "ProtectKernelModules=")) + return 0; + + return seccomp_load_filter_set(SCMP_ACT_ALLOW, syscall_filter_sets + SYSCALL_FILTER_SET_MODULE, SCMP_ACT_ERRNO(EPERM)); +} + +static int apply_private_devices(const Unit *u, const ExecContext *c) { + assert(c); + + /* If PrivateDevices= is set, also turn off iopl and all @raw-io syscalls. */ + + if (skip_seccomp_unavailable(u, "PrivateDevices=")) + return 0; + + return seccomp_load_filter_set(SCMP_ACT_ALLOW, syscall_filter_sets + SYSCALL_FILTER_SET_RAW_IO, SCMP_ACT_ERRNO(EPERM)); +} + #endif static void do_idle_pipe_dance(int idle_pipe[4]) { assert(idle_pipe); - idle_pipe[1] = safe_close(idle_pipe[1]); idle_pipe[2] = safe_close(idle_pipe[2]); @@ -1384,6 +1569,7 @@ static void do_idle_pipe_dance(int idle_pipe[4]) { } static int build_environment( + Unit *u, const ExecContext *c, const ExecParameters *p, unsigned n_fds, @@ -1398,10 +1584,11 @@ static int build_environment( unsigned n_env = 0; char *x; + assert(u); assert(c); assert(ret); - our_env = new0(char*, 12); + our_env = new0(char*, 14); if (!our_env) return -ENOMEM; @@ -1436,6 +1623,16 @@ static int build_environment( our_env[n_env++] = x; } + /* If this is D-Bus, tell the nss-systemd module, since it relies on being able to use D-Bus look up dynamic + * users via PID 1, possibly dead-locking the dbus daemon. This way it will not use D-Bus to resolve names, but + * check the database directly. */ + if (unit_has_name(u, SPECIAL_DBUS_SERVICE)) { + x = strdup("SYSTEMD_NSS_BYPASS_BUS=1"); + if (!x) + return -ENOMEM; + our_env[n_env++] = x; + } + if (home) { x = strappend("HOME=", home); if (!x) @@ -1462,6 +1659,13 @@ static int build_environment( our_env[n_env++] = x; } + if (!sd_id128_is_null(u->invocation_id)) { + if (asprintf(&x, "INVOCATION_ID=" SD_ID128_FORMAT_STR, SD_ID128_FORMAT_VAL(u->invocation_id)) < 0) + return -ENOMEM; + + our_env[n_env++] = x; + } + if (exec_context_needs_term(c)) { const char *tty_path, *term = NULL; @@ -1547,7 +1751,10 @@ static bool exec_needs_mount_namespace( if (context->private_devices || context->protect_system != PROTECT_SYSTEM_NO || - context->protect_home != PROTECT_HOME_NO) + context->protect_home != PROTECT_HOME_NO || + context->protect_kernel_tunables || + context->protect_kernel_modules || + context->protect_control_groups) return true; return false; @@ -1574,9 +1781,9 @@ static int setup_private_users(uid_t uid, gid_t gid) { asprintf(&uid_map, "0 0 1\n" /* Map root → root */ UID_FMT " " UID_FMT " 1\n", /* Map $UID → $UID */ - uid, uid); /* The case where the above is the same */ + uid, uid); else - uid_map = strdup("0 0 1\n"); + uid_map = strdup("0 0 1\n"); /* The case where the above is the same */ if (!uid_map) return -ENOMEM; @@ -1706,6 +1913,197 @@ static int setup_private_users(uid_t uid, gid_t gid) { return 0; } +static int setup_runtime_directory( + const ExecContext *context, + const ExecParameters *params, + uid_t uid, + gid_t gid) { + + char **rt; + int r; + + assert(context); + assert(params); + + STRV_FOREACH(rt, context->runtime_directory) { + _cleanup_free_ char *p; + + p = strjoin(params->runtime_prefix, "/", *rt, NULL); + if (!p) + return -ENOMEM; + + r = mkdir_p_label(p, context->runtime_directory_mode); + if (r < 0) + return r; + + r = chmod_and_chown(p, context->runtime_directory_mode, uid, gid); + if (r < 0) + return r; + } + + return 0; +} + +static int setup_smack( + const ExecContext *context, + const ExecCommand *command) { + +#ifdef HAVE_SMACK + int r; + + assert(context); + assert(command); + + if (!mac_smack_use()) + return 0; + + if (context->smack_process_label) { + r = mac_smack_apply_pid(0, context->smack_process_label); + if (r < 0) + return r; + } +#ifdef SMACK_DEFAULT_PROCESS_LABEL + else { + _cleanup_free_ char *exec_label = NULL; + + r = mac_smack_read(command->path, SMACK_ATTR_EXEC, &exec_label); + if (r < 0 && r != -ENODATA && r != -EOPNOTSUPP) + return r; + + r = mac_smack_apply_pid(0, exec_label ? : SMACK_DEFAULT_PROCESS_LABEL); + if (r < 0) + return r; + } +#endif +#endif + + return 0; +} + +static int compile_read_write_paths( + const ExecContext *context, + const ExecParameters *params, + char ***ret) { + + _cleanup_strv_free_ char **l = NULL; + char **rt; + + /* Compile the list of writable paths. This is the combination of the explicitly configured paths, plus all + * runtime directories. */ + + if (strv_isempty(context->read_write_paths) && + strv_isempty(context->runtime_directory)) { + *ret = NULL; /* NOP if neither is set */ + return 0; + } + + l = strv_copy(context->read_write_paths); + if (!l) + return -ENOMEM; + + STRV_FOREACH(rt, context->runtime_directory) { + char *s; + + s = strjoin(params->runtime_prefix, "/", *rt, NULL); + if (!s) + return -ENOMEM; + + if (strv_consume(&l, s) < 0) + return -ENOMEM; + } + + *ret = l; + l = NULL; + + return 0; +} + +static int apply_mount_namespace(Unit *u, const ExecContext *context, + const ExecParameters *params, + ExecRuntime *runtime) { + int r; + _cleanup_free_ char **rw = NULL; + char *tmp = NULL, *var = NULL; + const char *root_dir = NULL; + NameSpaceInfo ns_info = { + .private_dev = context->private_devices, + .protect_control_groups = context->protect_control_groups, + .protect_kernel_tunables = context->protect_kernel_tunables, + .protect_kernel_modules = context->protect_kernel_modules, + }; + + assert(context); + + /* The runtime struct only contains the parent of the private /tmp, + * which is non-accessible to world users. Inside of it there's a /tmp + * that is sticky, and that's the one we want to use here. */ + + if (context->private_tmp && runtime) { + if (runtime->tmp_dir) + tmp = strjoina(runtime->tmp_dir, "/tmp"); + if (runtime->var_tmp_dir) + var = strjoina(runtime->var_tmp_dir, "/tmp"); + } + + r = compile_read_write_paths(context, params, &rw); + if (r < 0) + return r; + + if (params->flags & EXEC_APPLY_CHROOT) + root_dir = context->root_directory; + + r = setup_namespace(root_dir, &ns_info, rw, + context->read_only_paths, + context->inaccessible_paths, + tmp, + var, + context->protect_home, + context->protect_system, + context->mount_flags); + + /* If we couldn't set up the namespace this is probably due to a + * missing capability. In this case, silently proceeed. */ + if (IN_SET(r, -EPERM, -EACCES)) { + log_open(); + log_unit_debug_errno(u, r, "Failed to set up namespace, assuming containerized execution, ignoring: %m"); + log_close(); + r = 0; + } + + return r; +} + +static int apply_working_directory(const ExecContext *context, + const ExecParameters *params, + const char *home, + const bool needs_mount_ns) { + const char *d; + const char *wd; + + assert(context); + + if (context->working_directory_home) + wd = home; + else if (context->working_directory) + wd = context->working_directory; + else + wd = "/"; + + if (params->flags & EXEC_APPLY_CHROOT) { + if (!needs_mount_ns && context->root_directory) + if (chroot(context->root_directory) < 0) + return -errno; + + d = wd; + } else + d = strjoina(strempty(context->root_directory), "/", strempty(wd)); + + if (chdir(d) < 0 && !context->working_directory_missing_ok) + return -errno; + + return 0; +} + static void append_socket_pair(int *array, unsigned *n, int pair[2]) { assert(array); assert(n); @@ -1723,11 +2121,12 @@ static int close_remaining_fds( const ExecParameters *params, ExecRuntime *runtime, DynamicCreds *dcreds, + int user_lookup_fd, int socket_fd, int *fds, unsigned n_fds) { unsigned n_dont_close = 0; - int dont_close[n_fds + 11]; + int dont_close[n_fds + 12]; assert(params); @@ -1755,9 +2154,73 @@ static int close_remaining_fds( append_socket_pair(dont_close, &n_dont_close, dcreds->group->storage_socket); } + if (user_lookup_fd >= 0) + dont_close[n_dont_close++] = user_lookup_fd; + return close_all_fds(dont_close, n_dont_close); } +static bool context_has_address_families(const ExecContext *c) { + assert(c); + + return c->address_families_whitelist || + !set_isempty(c->address_families); +} + +static bool context_has_syscall_filters(const ExecContext *c) { + assert(c); + + return c->syscall_whitelist || + !set_isempty(c->syscall_filter) || + !set_isempty(c->syscall_archs); +} + +static bool context_has_no_new_privileges(const ExecContext *c) { + assert(c); + + if (c->no_new_privileges) + return true; + + if (have_effective_cap(CAP_SYS_ADMIN)) /* if we are privileged, we don't need NNP */ + return false; + + return context_has_address_families(c) || /* we need NNP if we have any form of seccomp and are unprivileged */ + c->memory_deny_write_execute || + c->restrict_realtime || + c->protect_kernel_tunables || + c->protect_kernel_modules || + c->private_devices || + context_has_syscall_filters(c); +} + +static int send_user_lookup( + Unit *unit, + int user_lookup_fd, + uid_t uid, + gid_t gid) { + + assert(unit); + + /* Send the resolved UID/GID to PID 1 after we learnt it. We send a single datagram, containing the UID/GID + * data as well as the unit name. Note that we suppress sending this if no user/group to resolve was + * specified. */ + + if (user_lookup_fd < 0) + return 0; + + if (!uid_is_valid(uid) && !gid_is_valid(gid)) + return 0; + + if (writev(user_lookup_fd, + (struct iovec[]) { + { .iov_base = &uid, .iov_len = sizeof(uid) }, + { .iov_base = &gid, .iov_len = sizeof(gid) }, + { .iov_base = unit->id, .iov_len = strlen(unit->id) }}, 3) < 0) + return -errno; + + return 0; +} + static int exec_child( Unit *unit, ExecCommand *command, @@ -1767,19 +2230,23 @@ static int exec_child( DynamicCreds *dcreds, char **argv, int socket_fd, + int named_iofds[3], int *fds, unsigned n_fds, char **files_env, + int user_lookup_fd, int *exit_status) { _cleanup_strv_free_ char **our_env = NULL, **pass_env = NULL, **accum_env = NULL, **final_argv = NULL; _cleanup_free_ char *mac_selinux_context_net = NULL; - const char *username = NULL, *home = NULL, *shell = NULL, *wd; + _cleanup_free_ gid_t *supplementary_gids = NULL; + const char *username = NULL, *groupname = NULL; + const char *home = NULL, *shell = NULL; dev_t journal_stream_dev = 0; ino_t journal_stream_ino = 0; bool needs_mount_namespace; uid_t uid = UID_INVALID; gid_t gid = GID_INVALID; - int i, r; + int i, r, ngids = 0; assert(unit); assert(command); @@ -1815,7 +2282,7 @@ static int exec_child( log_forget_fds(); - r = close_remaining_fds(params, runtime, dcreds, socket_fd, fds, n_fds); + r = close_remaining_fds(params, runtime, dcreds, user_lookup_fd, socket_fd, fds, n_fds); if (r < 0) { *exit_status = EXIT_FDS; return r; @@ -1862,7 +2329,7 @@ static int exec_child( return r; } - if (uid == UID_INVALID || gid == GID_INVALID) { + if (!uid_is_valid(uid) || !gid_is_valid(gid)) { *exit_status = EXIT_USER; return -ESRCH; } @@ -1871,55 +2338,53 @@ static int exec_child( username = dcreds->user->name; } else { - if (context->user) { - username = context->user; - r = get_user_creds(&username, &uid, &gid, &home, &shell); - if (r < 0) { - *exit_status = EXIT_USER; - return r; - } - - /* Don't set $HOME or $SHELL if they are are not particularly enlightening anyway. */ - if (isempty(home) || path_equal(home, "/")) - home = NULL; + r = get_fixed_user(context, &username, &uid, &gid, &home, &shell); + if (r < 0) { + *exit_status = EXIT_USER; + return r; + } - if (isempty(shell) || PATH_IN_SET(shell, - "/bin/nologin", - "/sbin/nologin", - "/usr/bin/nologin", - "/usr/sbin/nologin")) - shell = NULL; + r = get_fixed_group(context, &groupname, &gid); + if (r < 0) { + *exit_status = EXIT_GROUP; + return r; } + } - if (context->group) { - const char *g = context->group; + /* Initialize user supplementary groups and get SupplementaryGroups= ones */ + r = get_supplementary_groups(context, username, groupname, gid, + &supplementary_gids, &ngids); + if (r < 0) { + *exit_status = EXIT_GROUP; + return r; + } - r = get_group_creds(&g, &gid); - if (r < 0) { - *exit_status = EXIT_GROUP; - return r; - } - } + r = send_user_lookup(unit, user_lookup_fd, uid, gid); + if (r < 0) { + *exit_status = EXIT_USER; + return r; } + user_lookup_fd = safe_close(user_lookup_fd); + /* If a socket is connected to STDIN/STDOUT/STDERR, we * must sure to drop O_NONBLOCK */ if (socket_fd >= 0) (void) fd_nonblock(socket_fd, false); - r = setup_input(context, params, socket_fd); + r = setup_input(context, params, socket_fd, named_iofds); if (r < 0) { *exit_status = EXIT_STDIN; return r; } - r = setup_output(unit, context, params, STDOUT_FILENO, socket_fd, basename(command->path), uid, gid, &journal_stream_dev, &journal_stream_ino); + r = setup_output(unit, context, params, STDOUT_FILENO, socket_fd, named_iofds, basename(command->path), uid, gid, &journal_stream_dev, &journal_stream_ino); if (r < 0) { *exit_status = EXIT_STDOUT; return r; } - r = setup_output(unit, context, params, STDERR_FILENO, socket_fd, basename(command->path), uid, gid, &journal_stream_dev, &journal_stream_ino); + r = setup_output(unit, context, params, STDERR_FILENO, socket_fd, named_iofds, basename(command->path), uid, gid, &journal_stream_dev, &journal_stream_ino); if (r < 0) { *exit_status = EXIT_STDERR; return r; @@ -2006,7 +2471,7 @@ static int exec_child( USER_PROCESS, username ? "root" : context->user); - if (context->user && is_terminal_input(context->std_input)) { + if (context->user) { r = chown_terminal(STDIN_FILENO, uid); if (r < 0) { *exit_status = EXIT_STDIN; @@ -2033,32 +2498,15 @@ static int exec_child( } if (!strv_isempty(context->runtime_directory) && params->runtime_prefix) { - char **rt; - - STRV_FOREACH(rt, context->runtime_directory) { - _cleanup_free_ char *p; - - p = strjoin(params->runtime_prefix, "/", *rt, NULL); - if (!p) { - *exit_status = EXIT_RUNTIME_DIRECTORY; - return -ENOMEM; - } - - r = mkdir_p_label(p, context->runtime_directory_mode); - if (r < 0) { - *exit_status = EXIT_RUNTIME_DIRECTORY; - return r; - } - - r = chmod_and_chown(p, context->runtime_directory_mode, uid, gid); - if (r < 0) { - *exit_status = EXIT_RUNTIME_DIRECTORY; - return r; - } + r = setup_runtime_directory(context, params, uid, gid); + if (r < 0) { + *exit_status = EXIT_RUNTIME_DIRECTORY; + return r; } } r = build_environment( + unit, context, params, n_fds, @@ -2092,49 +2540,16 @@ static int exec_child( } accum_env = strv_env_clean(accum_env); - umask(context->umask); + (void) umask(context->umask); if ((params->flags & EXEC_APPLY_PERMISSIONS) && !command->privileged) { - r = enforce_groups(context, username, gid); - if (r < 0) { - *exit_status = EXIT_GROUP; - return r; - } -#ifdef HAVE_SMACK - if (context->smack_process_label) { - r = mac_smack_apply_pid(0, context->smack_process_label); - if (r < 0) { - *exit_status = EXIT_SMACK_PROCESS_LABEL; - return r; - } - } -#ifdef SMACK_DEFAULT_PROCESS_LABEL - else { - _cleanup_free_ char *exec_label = NULL; - - r = mac_smack_read(command->path, SMACK_ATTR_EXEC, &exec_label); - if (r < 0 && r != -ENODATA && r != -EOPNOTSUPP) { - *exit_status = EXIT_SMACK_PROCESS_LABEL; - return r; - } - - r = mac_smack_apply_pid(0, exec_label ? : SMACK_DEFAULT_PROCESS_LABEL); - if (r < 0) { - *exit_status = EXIT_SMACK_PROCESS_LABEL; - return r; - } - } -#endif -#endif -#ifdef HAVE_PAM if (context->pam_name && username) { - r = setup_pam(context->pam_name, username, uid, context->tty_path, &accum_env, fds, n_fds); + r = setup_pam(context->pam_name, username, uid, gid, context->tty_path, &accum_env, fds, n_fds); if (r < 0) { *exit_status = EXIT_PAM; return r; } } -#endif } if (context->private_network && runtime && runtime->netns_storage_socket[0] >= 0) { @@ -2146,75 +2561,27 @@ static int exec_child( } needs_mount_namespace = exec_needs_mount_namespace(context, params, runtime); - if (needs_mount_namespace) { - char *tmp = NULL, *var = NULL; - - /* The runtime struct only contains the parent - * of the private /tmp, which is - * non-accessible to world users. Inside of it - * there's a /tmp that is sticky, and that's - * the one we want to use here. */ - - if (context->private_tmp && runtime) { - if (runtime->tmp_dir) - tmp = strjoina(runtime->tmp_dir, "/tmp"); - if (runtime->var_tmp_dir) - var = strjoina(runtime->var_tmp_dir, "/tmp"); - } - - r = setup_namespace( - (params->flags & EXEC_APPLY_CHROOT) ? context->root_directory : NULL, - context->read_write_paths, - context->read_only_paths, - context->inaccessible_paths, - tmp, - var, - context->private_devices, - context->protect_home, - context->protect_system, - context->mount_flags); - - /* If we couldn't set up the namespace this is - * probably due to a missing capability. In this case, - * silently proceeed. */ - if (r == -EPERM || r == -EACCES) { - log_open(); - log_unit_debug_errno(unit, r, "Failed to set up namespace, assuming containerized execution, ignoring: %m"); - log_close(); - } else if (r < 0) { + r = apply_mount_namespace(unit, context, params, runtime); + if (r < 0) { *exit_status = EXIT_NAMESPACE; return r; } } - if (context->working_directory_home) - wd = home; - else if (context->working_directory) - wd = context->working_directory; - else - wd = "/"; - - if (params->flags & EXEC_APPLY_CHROOT) { - if (!needs_mount_namespace && context->root_directory) - if (chroot(context->root_directory) < 0) { - *exit_status = EXIT_CHROOT; - return -errno; - } - - if (chdir(wd) < 0 && - !context->working_directory_missing_ok) { - *exit_status = EXIT_CHDIR; - return -errno; - } - } else { - const char *d; + /* Apply just after mount namespace setup */ + r = apply_working_directory(context, params, home, needs_mount_namespace); + if (r < 0) { + *exit_status = EXIT_CHROOT; + return r; + } - d = strjoina(strempty(context->root_directory), "/", strempty(wd)); - if (chdir(d) < 0 && - !context->working_directory_missing_ok) { - *exit_status = EXIT_CHDIR; - return -errno; + /* Drop groups as early as possbile */ + if ((params->flags & EXEC_APPLY_PERMISSIONS) && !command->privileged) { + r = enforce_groups(context, gid, supplementary_gids, ngids); + if (r < 0) { + *exit_status = EXIT_GROUP; + return r; } } @@ -2259,11 +2626,6 @@ static int exec_child( if ((params->flags & EXEC_APPLY_PERMISSIONS) && !command->privileged) { - bool use_address_families = context->address_families_whitelist || - !set_isempty(context->address_families); - bool use_syscall_filter = context->syscall_whitelist || - !set_isempty(context->syscall_filter) || - !set_isempty(context->syscall_archs); int secure_bits = context->secure_bits; for (i = 0; i < _RLIMIT_MAX; i++) { @@ -2330,6 +2692,41 @@ static int exec_child( } } + /* Apply the MAC contexts late, but before seccomp syscall filtering, as those should really be last to + * influence our own codepaths as little as possible. Moreover, applying MAC contexts usually requires + * syscalls that are subject to seccomp filtering, hence should probably be applied before the syscalls + * are restricted. */ + +#ifdef HAVE_SELINUX + if (mac_selinux_use()) { + char *exec_context = mac_selinux_context_net ?: context->selinux_context; + + if (exec_context) { + r = setexeccon(exec_context); + if (r < 0) { + *exit_status = EXIT_SELINUX_CONTEXT; + return r; + } + } + } +#endif + + r = setup_smack(context, command); + if (r < 0) { + *exit_status = EXIT_SMACK_PROCESS_LABEL; + return r; + } + +#ifdef HAVE_APPARMOR + if (context->apparmor_profile && mac_apparmor_use()) { + r = aa_change_onexec(context->apparmor_profile); + if (r < 0 && !context->apparmor_profile_ignore) { + *exit_status = EXIT_APPARMOR_PROFILE; + return -errno; + } + } +#endif + /* PR_GET_SECUREBITS is not privileged, while * PR_SET_SECUREBITS is. So to suppress * potential EPERMs we'll try not to call @@ -2340,16 +2737,15 @@ static int exec_child( return -errno; } - if (context->no_new_privileges || - (!have_effective_cap(CAP_SYS_ADMIN) && (use_address_families || context->memory_deny_write_execute || context->restrict_realtime || use_syscall_filter))) + if (context_has_no_new_privileges(context)) if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) { *exit_status = EXIT_NO_NEW_PRIVILEGES; return -errno; } #ifdef HAVE_SECCOMP - if (use_address_families) { - r = apply_address_families(context); + if (context_has_address_families(context)) { + r = apply_address_families(unit, context); if (r < 0) { *exit_status = EXIT_ADDRESS_FAMILIES; return r; @@ -2357,7 +2753,7 @@ static int exec_child( } if (context->memory_deny_write_execute) { - r = apply_memory_deny_write_execute(context); + r = apply_memory_deny_write_execute(unit, context); if (r < 0) { *exit_status = EXIT_SECCOMP; return r; @@ -2365,42 +2761,44 @@ static int exec_child( } if (context->restrict_realtime) { - r = apply_restrict_realtime(context); + r = apply_restrict_realtime(unit, context); if (r < 0) { *exit_status = EXIT_SECCOMP; return r; } } - if (use_syscall_filter) { - r = apply_seccomp(context); + if (context->protect_kernel_tunables) { + r = apply_protect_sysctl(unit, context); if (r < 0) { *exit_status = EXIT_SECCOMP; return r; } } -#endif -#ifdef HAVE_SELINUX - if (mac_selinux_use()) { - char *exec_context = mac_selinux_context_net ?: context->selinux_context; + if (context->protect_kernel_modules) { + r = apply_protect_kernel_modules(unit, context); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return r; + } + } - if (exec_context) { - r = setexeccon(exec_context); - if (r < 0) { - *exit_status = EXIT_SELINUX_CONTEXT; - return r; - } + if (context->private_devices) { + r = apply_private_devices(unit, context); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return r; } } -#endif -#ifdef HAVE_APPARMOR - if (context->apparmor_profile && mac_apparmor_use()) { - r = aa_change_onexec(context->apparmor_profile); - if (r < 0 && !context->apparmor_profile_ignore) { - *exit_status = EXIT_APPARMOR_PROFILE; - return -errno; + /* This really should remain the last step before the execve(), to make sure our own code is unaffected + * by the filter as little as possible. */ + if (context_has_syscall_filters(context)) { + r = apply_seccomp(unit, context); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return r; } } #endif @@ -2444,6 +2842,7 @@ int exec_spawn(Unit *unit, int *fds = NULL; unsigned n_fds = 0; _cleanup_free_ char *line = NULL; int socket_fd, r; + int named_iofds[3] = { -1, -1, -1 }; char **argv; pid_t pid; @@ -2470,6 +2869,10 @@ int exec_spawn(Unit *unit, n_fds = params->n_fds; } + r = exec_context_named_iofds(unit, context, params, named_iofds); + if (r < 0) + return log_unit_error_errno(unit, r, "Failed to load a named file descriptor: %m"); + r = exec_context_load_environment(unit, context, &files_env); if (r < 0) return log_unit_error_errno(unit, r, "Failed to load environment files: %m"); @@ -2499,8 +2902,10 @@ int exec_spawn(Unit *unit, dcreds, argv, socket_fd, + named_iofds, fds, n_fds, files_env, + unit->manager->user_lookup_fds[1], &exit_status); if (r < 0) { log_open(); @@ -2560,6 +2965,9 @@ void exec_context_done(ExecContext *c) { for (l = 0; l < ELEMENTSOF(c->rlimit); l++) c->rlimit[l] = mfree(c->rlimit[l]); + for (l = 0; l < 3; l++) + c->stdio_fdname[l] = mfree(c->stdio_fdname[l]); + c->working_directory = mfree(c->working_directory); c->root_directory = mfree(c->root_directory); c->tty_path = mfree(c->tty_path); @@ -2658,6 +3066,56 @@ static void invalid_env(const char *p, void *userdata) { log_unit_error(info->unit, "Ignoring invalid environment assignment '%s': %s", p, info->path); } +const char* exec_context_fdname(const ExecContext *c, int fd_index) { + assert(c); + + switch (fd_index) { + case STDIN_FILENO: + if (c->std_input != EXEC_INPUT_NAMED_FD) + return NULL; + return c->stdio_fdname[STDIN_FILENO] ?: "stdin"; + case STDOUT_FILENO: + if (c->std_output != EXEC_OUTPUT_NAMED_FD) + return NULL; + return c->stdio_fdname[STDOUT_FILENO] ?: "stdout"; + case STDERR_FILENO: + if (c->std_error != EXEC_OUTPUT_NAMED_FD) + return NULL; + return c->stdio_fdname[STDERR_FILENO] ?: "stderr"; + default: + return NULL; + } +} + +int exec_context_named_iofds(Unit *unit, const ExecContext *c, const ExecParameters *p, int named_iofds[3]) { + unsigned i, targets; + const char *stdio_fdname[3]; + + assert(c); + assert(p); + + targets = (c->std_input == EXEC_INPUT_NAMED_FD) + + (c->std_output == EXEC_OUTPUT_NAMED_FD) + + (c->std_error == EXEC_OUTPUT_NAMED_FD); + + for (i = 0; i < 3; i++) + stdio_fdname[i] = exec_context_fdname(c, i); + + for (i = 0; i < p->n_fds && targets > 0; i++) + if (named_iofds[STDIN_FILENO] < 0 && c->std_input == EXEC_INPUT_NAMED_FD && stdio_fdname[STDIN_FILENO] && streq(p->fd_names[i], stdio_fdname[STDIN_FILENO])) { + named_iofds[STDIN_FILENO] = p->fds[i]; + targets--; + } else if (named_iofds[STDOUT_FILENO] < 0 && c->std_output == EXEC_OUTPUT_NAMED_FD && stdio_fdname[STDOUT_FILENO] && streq(p->fd_names[i], stdio_fdname[STDOUT_FILENO])) { + named_iofds[STDOUT_FILENO] = p->fds[i]; + targets--; + } else if (named_iofds[STDERR_FILENO] < 0 && c->std_error == EXEC_OUTPUT_NAMED_FD && stdio_fdname[STDERR_FILENO] && streq(p->fd_names[i], stdio_fdname[STDERR_FILENO])) { + named_iofds[STDERR_FILENO] = p->fds[i]; + targets--; + } + + return (targets == 0 ? 0 : -ENOENT); +} + int exec_context_load_environment(Unit *unit, const ExecContext *c, char ***l) { char **i, **r = NULL; @@ -2803,6 +3261,9 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) { "%sNonBlocking: %s\n" "%sPrivateTmp: %s\n" "%sPrivateDevices: %s\n" + "%sProtectKernelTunables: %s\n" + "%sProtectKernelModules: %s\n" + "%sProtectControlGroups: %s\n" "%sPrivateNetwork: %s\n" "%sPrivateUsers: %s\n" "%sProtectHome: %s\n" @@ -2816,6 +3277,9 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) { prefix, yes_no(c->non_blocking), prefix, yes_no(c->private_tmp), prefix, yes_no(c->private_devices), + prefix, yes_no(c->protect_kernel_tunables), + prefix, yes_no(c->protect_kernel_modules), + prefix, yes_no(c->protect_control_groups), prefix, yes_no(c->private_network), prefix, yes_no(c->private_users), prefix, protect_home_to_string(c->protect_home), @@ -3159,7 +3623,8 @@ char *exec_command_line(char **argv) { STRV_FOREACH(a, argv) k += strlen(*a)+3; - if (!(n = new(char, k))) + n = new(char, k); + if (!n) return NULL; p = n; @@ -3348,9 +3813,7 @@ ExecRuntime *exec_runtime_unref(ExecRuntime *r) { free(r->tmp_dir); free(r->var_tmp_dir); safe_close_pair(r->netns_storage_socket); - free(r); - - return NULL; + return mfree(r); } int exec_runtime_serialize(Unit *u, ExecRuntime *rt, FILE *f, FDSet *fds) { @@ -3506,7 +3969,8 @@ static const char* const exec_input_table[_EXEC_INPUT_MAX] = { [EXEC_INPUT_TTY] = "tty", [EXEC_INPUT_TTY_FORCE] = "tty-force", [EXEC_INPUT_TTY_FAIL] = "tty-fail", - [EXEC_INPUT_SOCKET] = "socket" + [EXEC_INPUT_SOCKET] = "socket", + [EXEC_INPUT_NAMED_FD] = "fd", }; DEFINE_STRING_TABLE_LOOKUP(exec_input, ExecInput); @@ -3521,7 +3985,8 @@ static const char* const exec_output_table[_EXEC_OUTPUT_MAX] = { [EXEC_OUTPUT_KMSG_AND_CONSOLE] = "kmsg+console", [EXEC_OUTPUT_JOURNAL] = "journal", [EXEC_OUTPUT_JOURNAL_AND_CONSOLE] = "journal+console", - [EXEC_OUTPUT_SOCKET] = "socket" + [EXEC_OUTPUT_SOCKET] = "socket", + [EXEC_OUTPUT_NAMED_FD] = "fd", }; DEFINE_STRING_TABLE_LOOKUP(exec_output, ExecOutput); |