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-rw-r--r--execute.c361
1 files changed, 315 insertions, 46 deletions
diff --git a/execute.c b/execute.c
index 4c6aa4eea9..bdb0f92179 100644
--- a/execute.c
+++ b/execute.c
@@ -32,6 +32,8 @@
#include <linux/sched.h>
#include <sys/types.h>
#include <sys/stat.h>
+#include <grp.h>
+#include <pwd.h>
#include "execute.h"
#include "strv.h"
@@ -293,7 +295,217 @@ static int setup_input(const ExecContext *context) {
}
}
-int exec_spawn(const ExecCommand *command, const ExecContext *context, int *fds, unsigned n_fds, pid_t *ret) {
+static int get_group_creds(const char *groupname, gid_t *gid) {
+ struct group *g;
+ unsigned long lu;
+
+ assert(groupname);
+ assert(gid);
+
+ /* We enforce some special rules for gid=0: in order to avoid
+ * NSS lookups for root we hardcode its data. */
+
+ if (streq(groupname, "root") || streq(groupname, "0")) {
+ *gid = 0;
+ return 0;
+ }
+
+ if (safe_atolu(groupname, &lu) >= 0) {
+ errno = 0;
+ g = getgrgid((gid_t) lu);
+ } else {
+ errno = 0;
+ g = getgrnam(groupname);
+ }
+
+ if (!g)
+ return errno != 0 ? -errno : -ESRCH;
+
+ *gid = g->gr_gid;
+ return 0;
+}
+
+static int get_user_creds(const char **username, uid_t *uid, gid_t *gid, const char **home) {
+ struct passwd *p;
+ unsigned long lu;
+
+ assert(username);
+ assert(*username);
+ assert(uid);
+ assert(gid);
+ assert(home);
+
+ /* We enforce some special rules for uid=0: in order to avoid
+ * NSS lookups for root we hardcode its data. */
+
+ if (streq(*username, "root") || streq(*username, "0")) {
+ *username = "root";
+ *uid = 0;
+ *gid = 0;
+ *home = "/root";
+ return 0;
+ }
+
+ if (safe_atolu(*username, &lu) >= 0) {
+ errno = 0;
+ p = getpwuid((uid_t) lu);
+
+ /* If there are multiple users with the same id, make
+ * sure to leave $USER to the configured value instead
+ * of the first occurence in the database. However if
+ * the uid was configured by a numeric uid, then let's
+ * pick the real username from /etc/passwd. */
+ if (*username && p)
+ *username = p->pw_name;
+ } else {
+ errno = 0;
+ p = getpwnam(*username);
+ }
+
+ if (!p)
+ return errno != 0 ? -errno : -ESRCH;
+
+ *uid = p->pw_uid;
+ *gid = p->pw_gid;
+ *home = p->pw_dir;
+ return 0;
+}
+
+static int enforce_groups(const ExecContext *context, const char *username, gid_t gid) {
+ bool keep_groups = false;
+ int r;
+
+ assert(context);
+
+ /* Lookup and ser GID and supplementary group list. Here too
+ * we avoid NSS lookups for gid=0. */
+
+ if (context->group || username) {
+
+ if (context->group)
+ if ((r = get_group_creds(context->group, &gid)) < 0)
+ return r;
+
+ /* First step, initialize groups from /etc/groups */
+ if (username && gid != 0) {
+ if (initgroups(username, gid) < 0)
+ return -errno;
+
+ keep_groups = true;
+ }
+
+ /* Second step, set our gids */
+ if (setresgid(gid, gid, gid) < 0)
+ return -errno;
+ }
+
+ if (context->supplementary_groups) {
+ int ngroups_max, k;
+ gid_t *gids;
+ char **i;
+
+ /* Final step, initialize any manually set supplementary groups */
+ ngroups_max = (int) sysconf(_SC_NGROUPS_MAX);
+
+ if (!(gids = new(gid_t, ngroups_max)))
+ return -ENOMEM;
+
+ if (keep_groups) {
+ if ((k = getgroups(ngroups_max, gids)) < 0) {
+ free(gids);
+ return -errno;
+ }
+ } else
+ k = 0;
+
+ STRV_FOREACH(i, context->supplementary_groups) {
+
+ if (k >= ngroups_max) {
+ free(gids);
+ return -E2BIG;
+ }
+
+ if ((r = get_group_creds(*i, gids+k)) < 0) {
+ free(gids);
+ return r;
+ }
+
+ k++;
+ }
+
+ if (setgroups(k, gids) < 0) {
+ free(gids);
+ return -errno;
+ }
+
+ free(gids);
+ }
+
+ return 0;
+}
+
+static int enforce_user(const ExecContext *context, uid_t uid) {
+ int r;
+ assert(context);
+
+ /* Sets (but doesn't lookup) the uid and make sure we keep the
+ * capabilities while doing so. */
+
+ if (context->capabilities) {
+ cap_t d;
+ static const cap_value_t bits[] = {
+ CAP_SETUID, /* Necessary so that we can run setresuid() below */
+ CAP_SETPCAP /* Necessary so that we can set PR_SET_SECUREBITS later on */
+ };
+
+ /* First step: If we need to keep capabilities but
+ * drop privileges we need to make sure we keep our
+ * caps, whiel we drop priviliges. */
+ if (uid != 0)
+ if (prctl(PR_SET_SECUREBITS, context->secure_bits|SECURE_KEEP_CAPS) < 0)
+ return -errno;
+
+ /* Second step: set the capabilites. This will reduce
+ * the capabilities to the minimum we need. */
+
+ if (!(d = cap_dup(context->capabilities)))
+ return -errno;
+
+ if (cap_set_flag(d, CAP_EFFECTIVE, ELEMENTSOF(bits), bits, CAP_SET) < 0 ||
+ cap_set_flag(d, CAP_PERMITTED, ELEMENTSOF(bits), bits, CAP_SET) < 0) {
+ r = -errno;
+ cap_free(d);
+ return r;
+ }
+
+ if (cap_set_proc(d) < 0) {
+ r = -errno;
+ cap_free(d);
+ return r;
+ }
+
+ cap_free(d);
+ }
+
+ /* Third step: actually set the uids */
+ if (setresuid(uid, uid, uid) < 0)
+ return -errno;
+
+ /* At this point we should have all necessary capabilities but
+ are otherwise a normal user. However, the caps might got
+ corrupted due to the setresuid() so we need clean them up
+ later. This is done outside of this call. */
+
+ return 0;
+}
+
+int exec_spawn(const ExecCommand *command,
+ const ExecContext *context,
+ int *fds, unsigned n_fds,
+ bool apply_permissions,
+ bool apply_chroot,
+ pid_t *ret) {
+
pid_t pid;
assert(command);
@@ -301,15 +513,19 @@ int exec_spawn(const ExecCommand *command, const ExecContext *context, int *fds,
assert(ret);
assert(fds || n_fds <= 0);
- log_debug("about to execute %s", command->path);
+ log_debug("About to execute %s", command->path);
if ((pid = fork()) < 0)
return -errno;
if (pid == 0) {
- char **e, **f = NULL;
int i, r;
sigset_t ss;
+ const char *username = NULL, *home = NULL;
+ uid_t uid = (uid_t) -1;
+ gid_t gid = (gid_t) -1;
+ char **our_env = NULL, **final_env = NULL;
+ unsigned n_env = 0;
/* child */
@@ -348,17 +564,6 @@ int exec_spawn(const ExecCommand *command, const ExecContext *context, int *fds,
}
}
- if (context->root_directory)
- if (chroot(context->root_directory) < 0) {
- r = EXIT_CHROOT;
- goto fail;
- }
-
- if (chdir(context->working_directory ? context->working_directory : "/") < 0) {
- r = EXIT_CHDIR;
- goto fail;
- }
-
if (context->nice_set)
if (setpriority(PRIO_PROCESS, 0, context->nice) < 0) {
r = EXIT_NICE;
@@ -396,6 +601,51 @@ int exec_spawn(const ExecCommand *command, const ExecContext *context, int *fds,
goto fail;
}
+ if (context->user) {
+ username = context->user;
+ if (get_user_creds(&username, &uid, &gid, &home) < 0) {
+ r = EXIT_USER;
+ goto fail;
+ }
+ }
+
+ if (apply_permissions)
+ if (enforce_groups(context, username, uid) < 0) {
+ r = EXIT_GROUP;
+ goto fail;
+ }
+
+ if (apply_chroot) {
+ if (context->root_directory)
+ if (chroot(context->root_directory) < 0) {
+ r = EXIT_CHROOT;
+ goto fail;
+ }
+
+ if (chdir(context->working_directory ? context->working_directory : "/") < 0) {
+ r = EXIT_CHDIR;
+ goto fail;
+ }
+ } else {
+
+ char *d;
+
+ if (asprintf(&d, "%s/%s",
+ context->root_directory ? context->root_directory : "",
+ context->working_directory ? context->working_directory : "") < 0) {
+ r = EXIT_MEMORY;
+ goto fail;
+ }
+
+ if (chdir(d) < 0) {
+ free(d);
+ r = EXIT_CHDIR;
+ goto fail;
+ }
+
+ free(d);
+ }
+
if (close_fds(fds, n_fds) < 0 ||
shift_fds(fds, n_fds) < 0 ||
flags_fds(fds, n_fds, context->non_blocking) < 0) {
@@ -403,59 +653,78 @@ int exec_spawn(const ExecCommand *command, const ExecContext *context, int *fds,
goto fail;
}
- for (i = 0; i < RLIMIT_NLIMITS; i++) {
- if (!context->rlimit[i])
- continue;
+ if (apply_permissions) {
- if (setrlimit(i, context->rlimit[i]) < 0) {
- r = EXIT_LIMITS;
- goto fail;
+ for (i = 0; i < RLIMIT_NLIMITS; i++) {
+ if (!context->rlimit[i])
+ continue;
+
+ if (setrlimit(i, context->rlimit[i]) < 0) {
+ r = EXIT_LIMITS;
+ goto fail;
+ }
}
- }
- if (context->secure_bits) {
+ if (context->user)
+ if (enforce_user(context, uid) < 0) {
+ r = EXIT_USER;
+ goto fail;
+ }
+
if (prctl(PR_SET_SECUREBITS, context->secure_bits) < 0) {
r = EXIT_SECUREBITS;
goto fail;
}
+
+ if (context->capabilities)
+ if (cap_set_proc(context->capabilities) < 0) {
+ r = EXIT_CAPABILITIES;
+ goto fail;
+ }
}
- if (n_fds > 0) {
- char a[64], b[64];
- char *listen_env[3] = {
- a,
- b,
- NULL
- };
+ if (!(our_env = new0(char*, 6))) {
+ r = EXIT_MEMORY;
+ goto fail;
+ }
- snprintf(a, sizeof(a), "LISTEN_PID=%llu", (unsigned long long) getpid());
- snprintf(b, sizeof(b), "LISTEN_FDS=%u", n_fds);
+ if (n_fds > 0)
+ if (asprintf(our_env + n_env++, "LISTEN_PID=%llu", (unsigned long long) getpid()) < 0 ||
+ asprintf(our_env + n_env++, "LISTEN_FDS=%u", n_fds) < 0) {
+ r = EXIT_MEMORY;
+ goto fail;
+ }
- a[sizeof(a)-1] = 0;
- b[sizeof(b)-1] = 0;
+ if (home)
+ if (asprintf(our_env + n_env++, "HOME=%s", home) < 0) {
+ r = EXIT_MEMORY;
+ goto fail;
+ }
- if (context->environment) {
- if (!(f = strv_merge(listen_env, context->environment))) {
- r = EXIT_MEMORY;
- goto fail;
- }
- e = f;
- } else
- e = listen_env;
+ if (username)
+ if (asprintf(our_env + n_env++, "LOGNAME=%s", username) < 0 ||
+ asprintf(our_env + n_env++, "USER=%s", username) < 0) {
+ r = EXIT_MEMORY;
+ goto fail;
+ }
- } else
- e = context->environment;
+ if (!(final_env = strv_env_merge(environ, our_env, context->environment, NULL))) {
+ r = EXIT_MEMORY;
+ goto fail;
+ }
- execve(command->path, command->argv, e);
+ execve(command->path, command->argv, final_env);
r = EXIT_EXEC;
fail:
- strv_free(f);
+ strv_free(our_env);
+ strv_free(final_env);
+
_exit(r);
}
- log_debug("executed %s as %llu", command->path, (unsigned long long) pid);
+ log_debug("Forked %s as %llu", command->path, (unsigned long long) pid);
*ret = pid;
return 0;
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-27 07:47:24 +0000