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-rw-r--r--src/execute.c205
1 files changed, 203 insertions, 2 deletions
diff --git a/src/execute.c b/src/execute.c
index 1a7871b4e0..ed10ea2bfb 100644
--- a/src/execute.c
+++ b/src/execute.c
@@ -37,6 +37,10 @@
#include <sys/mount.h>
#include <linux/fs.h>
+#ifdef HAVE_PAM
+#include <security/pam_appl.h>
+#endif
+
#include "execute.h"
#include "strv.h"
#include "macro.h"
@@ -720,6 +724,164 @@ static int enforce_user(const ExecContext *context, uid_t uid) {
return 0;
}
+#ifdef HAVE_PAM
+
+static int null_conv(
+ int num_msg,
+ const struct pam_message **msg,
+ struct pam_response **resp,
+ void *appdata_ptr) {
+
+ /* We don't support conversations */
+
+ return PAM_CONV_ERR;
+}
+
+static int setup_pam(
+ const char *name,
+ const char *user,
+ const char *tty,
+ char ***pam_env,
+ int fds[], unsigned n_fds) {
+
+ static const struct pam_conv conv = {
+ .conv = null_conv,
+ .appdata_ptr = NULL
+ };
+
+ pam_handle_t *handle = NULL;
+ sigset_t ss, old_ss;
+ int pam_code = PAM_SUCCESS;
+ char **e = NULL;
+ bool close_session = false;
+ pid_t pam_pid = 0, parent_pid;
+
+ assert(name);
+ assert(user);
+ assert(pam_env);
+
+ /* We set up PAM in the parent process, then fork. The child
+ * will then stay around untill killed via PR_GET_PDEATHSIG or
+ * systemd via the cgroup logic. It will then remove the PAM
+ * session again. The parent process will exec() the actual
+ * daemon. We do things this way to ensure that the main PID
+ * of the daemon is the one we initially fork()ed. */
+
+ if ((pam_code = pam_start(name, user, &conv, &handle)) != PAM_SUCCESS) {
+ handle = NULL;
+ goto fail;
+ }
+
+ if (tty)
+ if ((pam_code = pam_set_item(handle, PAM_TTY, tty)) != PAM_SUCCESS)
+ goto fail;
+
+ if ((pam_code = pam_acct_mgmt(handle, PAM_SILENT)) != PAM_SUCCESS)
+ goto fail;
+
+ if ((pam_code = pam_open_session(handle, PAM_SILENT)) != PAM_SUCCESS)
+ goto fail;
+
+ close_session = true;
+
+ if ((pam_code = pam_setcred(handle, PAM_ESTABLISH_CRED | PAM_SILENT)) != PAM_SUCCESS)
+ goto fail;
+
+ if ((!(e = pam_getenvlist(handle)))) {
+ pam_code = PAM_BUF_ERR;
+ goto fail;
+ }
+
+ /* Block SIGTERM, so that we know that it won't get lost in
+ * the child */
+ if (sigemptyset(&ss) < 0 ||
+ sigaddset(&ss, SIGTERM) < 0 ||
+ sigprocmask(SIG_BLOCK, &ss, &old_ss) < 0)
+ goto fail;
+
+ parent_pid = getpid();
+
+ if ((pam_pid = fork()) < 0)
+ goto fail;
+
+ if (pam_pid == 0) {
+ int sig;
+ int r = EXIT_PAM;
+
+ /* The child's job is to reset the PAM session on
+ * termination */
+
+ /* This string must fit in 10 chars (i.e. the length
+ * of "/sbin/init") */
+ rename_process("sd:pam");
+
+ /* Make sure we don't keep open the passed fds in this
+ child. We assume that otherwise only those fds are
+ open here that have been opened by PAM. */
+ close_many(fds, n_fds);
+
+ /* Wait until our parent died. This will most likely
+ * not work since the kernel does not allow
+ * unpriviliged paretns kill their priviliged children
+ * this way. We rely on the control groups kill logic
+ * to do the rest for us. */
+ if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
+ goto child_finish;
+
+ /* Check if our parent process might already have
+ * died? */
+ if (getppid() == parent_pid) {
+ if (sigwait(&ss, &sig) < 0)
+ goto child_finish;
+
+ assert(sig == SIGTERM);
+ }
+
+ /* Only if our parent died we'll end the session */
+ if (getppid() != parent_pid)
+ if ((pam_code = pam_close_session(handle, PAM_DATA_SILENT)) != PAM_SUCCESS)
+ goto child_finish;
+
+ r = 0;
+
+ child_finish:
+ pam_end(handle, pam_code | PAM_DATA_SILENT);
+ _exit(r);
+ }
+
+ /* If the child was forked off successfully it will do all the
+ * cleanups, so forget about the handle here. */
+ handle = NULL;
+
+ /* Unblock SIGSUR1 again in the parent */
+ if (sigprocmask(SIG_SETMASK, &old_ss, NULL) < 0)
+ goto fail;
+
+ /* We close the log explicitly here, since the PAM modules
+ * might have opened it, but we don't want this fd around. */
+ closelog();
+
+ return 0;
+
+fail:
+ if (handle) {
+ if (close_session)
+ pam_code = pam_close_session(handle, PAM_DATA_SILENT);
+
+ pam_end(handle, pam_code | PAM_DATA_SILENT);
+ }
+
+ strv_free(e);
+
+ closelog();
+
+ if (pam_pid > 1)
+ kill(pam_pid, SIGTERM);
+
+ return EXIT_PAM;
+}
+#endif
+
int exec_spawn(ExecCommand *command,
char **argv,
const ExecContext *context,
@@ -777,13 +939,17 @@ int exec_spawn(ExecCommand *command,
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;
+ char **our_env = NULL, **pam_env = NULL, **final_env = NULL;
unsigned n_env = 0;
int saved_stdout = -1, saved_stdin = -1;
bool keep_stdout = false, keep_stdin = false;
/* child */
+ /* This string must fit in 10 chars (i.e. the length
+ * of "/sbin/init") */
+ rename_process("sd:exec");
+
/* We reset exactly these signals, since they are the
* only ones we set to SIG_IGN in the main daemon. All
* others we leave untouched because we set them to
@@ -928,6 +1094,25 @@ int exec_spawn(ExecCommand *command,
}
}
+#ifdef HAVE_PAM
+ if (context->pam_name && username) {
+ /* Make sure no fds leak into the PAM
+ * supervisor process. We will call this later
+ * on again to make sure that any fds leaked
+ * by the PAM modules get closed before our
+ * exec(). */
+ if (close_all_fds(fds, n_fds) < 0) {
+ r = EXIT_FDS;
+ goto fail;
+ }
+
+ if (setup_pam(context->pam_name, username, context->tty_path, &pam_env, fds, n_fds) < 0) {
+ r = EXIT_PAM;
+ goto fail;
+ }
+ }
+#endif
+
if (apply_permissions)
if (enforce_groups(context, username, uid) < 0) {
r = EXIT_GROUP;
@@ -1049,7 +1234,13 @@ int exec_spawn(ExecCommand *command,
assert(n_env <= 6);
- if (!(final_env = strv_env_merge(environment, our_env, context->environment, NULL))) {
+ if (!(final_env = strv_env_merge(
+ 4,
+ environment,
+ our_env,
+ context->environment,
+ pam_env,
+ NULL))) {
r = EXIT_MEMORY;
goto fail;
}
@@ -1060,6 +1251,7 @@ int exec_spawn(ExecCommand *command,
fail:
strv_free(our_env);
strv_free(final_env);
+ strv_free(pam_env);
if (saved_stdin >= 0)
close_nointr_nofail(saved_stdin);
@@ -1133,6 +1325,9 @@ void exec_context_done(ExecContext *c) {
strv_free(c->supplementary_groups);
c->supplementary_groups = NULL;
+ free(c->pam_name);
+ c->pam_name = NULL;
+
if (c->capabilities) {
cap_free(c->capabilities);
c->capabilities = NULL;
@@ -1332,6 +1527,9 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {
fputs("\n", f);
}
+ if (c->pam_name)
+ fprintf(f, "%sPAMName: %s", prefix, c->pam_name);
+
if (strv_length(c->read_write_dirs) > 0) {
fprintf(f, "%sReadWriteDirs:", prefix);
strv_fprintf(f, c->read_write_dirs);
@@ -1613,6 +1811,9 @@ const char* exit_status_to_string(ExitStatus status) {
case EXIT_TCPWRAP:
return "TCPWRAP";
+ case EXIT_PAM:
+ return "PAM";
+
default:
return NULL;
}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-10 16:15:55 +0000