open pam sessions with right user and remove setusercontext shim

[opendoas.git] / doas_pam.c

diff --git a/doas_pam.c b/doas_pam.c
index f8b6e63f402595bf5bcd87db0138a45e17330f4f..4f2731d5e133d12b664a63709c470b17d025a9be 100644 (file)
--- a/doas_pam.c
+++ b/doas_pam.c
@@ -39,6 +39,12 @@ static pam_handle_t *pamh = NULL;
 static sig_atomic_t volatile caught_signal = 0;
 static char doas_prompt[128];
 
+static void
+catchsig(int sig)
+{
+       caught_signal = sig;
+}
+
 static char *
 prompt(const char *msg, int echo_on, int *pam)
 {
@@ -48,7 +54,7 @@ prompt(const char *msg, int echo_on, int *pam)
 
        /* overwrite default prompt if it matches "Password:[ ]" */
        if (strncmp(msg,"Password:", 9) == 0 &&
-                       (msg[9] == '\0' || (msg[9] == ' ' && msg[10] == '\0')))
+           (msg[9] == '\0' || (msg[9] == ' ' && msg[10] == '\0')))
                prompt = doas_prompt;
        else
                prompt = msg;
@@ -86,7 +92,7 @@ doas_pam_conv(int nmsgs, const struct pam_message **msgs,
                case PAM_ERROR_MSG:
                case PAM_TEXT_INFO:
                        if (fprintf(style == PAM_ERROR_MSG ? stderr : stdout,
-                                       "%s\n", msgs[i]->msg) < 0)
+                           "%s\n", msgs[i]->msg) < 0)
                                goto fail;
                        break;
 
@@ -117,14 +123,8 @@ fail:
        return PAM_CONV_ERR;
 }
 
-static void
-catchsig(int sig)
-{
-       caught_signal = sig;
-}
-
 int
-doas_pam(char *name, int interactive, int nopass)
+doas_pam(const char *user, const char* ruser, int interactive, int nopass)
 {
        static const struct pam_conv conv = {
                .conv = doas_pam_conv,
@@ -134,23 +134,22 @@ doas_pam(char *name, int interactive, int nopass)
        pid_t child;
        int ret;
 
-       if (!name)
+       if (!user || !ruser)
                return 0;
 
-       ret = pam_start(PAM_SERVICE_NAME, name, &conv, &pamh);
-       if (ret != PAM_SUCCESS)
-               errx(1, "pam_start(\"%s\", \"%s\", ?, ?): failed\n",
-                               PAM_SERVICE_NAME, name);
+       /* pam needs the real root */
+       if(setuid(0))
+               errx(1, "setuid");
 
-       ret = pam_set_item(pamh, PAM_USER, name);
+       ret = pam_start(PAM_SERVICE_NAME, ruser, &conv, &pamh);
        if (ret != PAM_SUCCESS)
-               errx(1, "pam_set_item(?, PAM_USER, \"%s\"): %s\n",
-                               name, pam_strerror(pamh, ret));
+               errx(1, "pam_start(\"%s\", \"%s\", ?, ?): failed\n",
+                   PAM_SERVICE_NAME, ruser);
 
-       ret = pam_set_item(pamh, PAM_RUSER, name);
+       ret = pam_set_item(pamh, PAM_RUSER, ruser);
        if (ret != PAM_SUCCESS)
-               errx(1, "pam_set_item(?, PAM_RUSER, \"%s\"): %s\n",
-                               name, pam_strerror(pamh, ret));
+               warn("pam_set_item(?, PAM_RUSER, \"%s\"): %s\n",
+                   pam_strerror(pamh, ret), ruser);
 
        if (isatty(0) && (ttydev = ttyname(0)) != NULL) {
                if (strncmp(ttydev, "/dev/", 5))
@@ -160,8 +159,8 @@ doas_pam(char *name, int interactive, int nopass)
 
                ret = pam_set_item(pamh, PAM_TTY, tty);
                if (ret != PAM_SUCCESS)
-                       errx(1, "pam_set_item(?, PAM_TTY, \"%s\"): %s\n",
-                                       tty, pam_strerror(pamh, ret));
+                       warn("pam_set_item(?, PAM_TTY, \"%s\"): %s\n",
+                           tty, pam_strerror(pamh, ret));
        }
 
        if (!nopass) {
@@ -173,14 +172,12 @@ doas_pam(char *name, int interactive, int nopass)
                if (gethostname(host, sizeof(host)))
                        snprintf(host, sizeof(host), "?");
                snprintf(doas_prompt, sizeof(doas_prompt),
-                               "\rdoas (%.32s@%.32s) password: ", name, host);
+                   "\rdoas (%.32s@%.32s) password: ", ruser, host);
 
                /* authenticate */
                ret = pam_authenticate(pamh, 0);
                if (ret != PAM_SUCCESS) {
-                       ret = pam_end(pamh, ret);
-                       if (ret != PAM_SUCCESS)
-                               errx(1, "pam_end(): %s\n", pam_strerror(pamh, ret));
+                       pam_end(pamh, ret);
                        return 0;
                }
        }
@@ -193,10 +190,14 @@ doas_pam(char *name, int interactive, int nopass)
        if (ret != PAM_SUCCESS)
                return 0;
 
+       ret = pam_set_item(pamh, PAM_USER, user);
+       if (ret != PAM_SUCCESS)
+               warn("pam_set_item(?, PAM_USER, \"%s\"): %s\n", user,
+                   pam_strerror(pamh, ret));
+
        ret = pam_setcred(pamh, PAM_ESTABLISH_CRED);
        if (ret != PAM_SUCCESS)
-               errx(1, "pam_setcred(?, PAM_ESTABLISH_CRED): %s\n",
-                               pam_strerror(pamh, ret));
+               warn("pam_setcred(?, PAM_ESTABLISH_CRED): %s\n", pam_strerror(pamh, ret));
 
        /* open session */
        ret = pam_open_session(pamh, 0);
@@ -233,10 +234,10 @@ doas_pam(char *name, int interactive, int nopass)
 
        /* unblock SIGTERM and SIGALRM to catch them */
        sigemptyset(&sigs);
-       if(sigaddset(&sigs, SIGTERM) ||
-                       sigaddset(&sigs, SIGALRM) ||
-                       sigaction(SIGTERM, &act, &oldact) ||
-                       sigprocmask(SIG_UNBLOCK, &sigs, NULL)) {
+       if (sigaddset(&sigs, SIGTERM) ||
+           sigaddset(&sigs, SIGALRM) ||
+           sigaction(SIGTERM, &act, &oldact) ||
+           sigprocmask(SIG_UNBLOCK, &sigs, NULL)) {
                warn("failed to set signal handler");
                caught_signal = 1;
        }
@@ -246,7 +247,7 @@ doas_pam(char *name, int interactive, int nopass)
                if (waitpid(child, &status, 0) != -1) {
                        if (WIFSIGNALED(status)) {
                                fprintf(stderr, "%s%s\n", strsignal(WTERMSIG(status)),
-                                               WCOREDUMP(status) ? " (core dumped)" : "");
+                                   WCOREDUMP(status) ? " (core dumped)" : "");
                                status = WTERMSIG(status) + 128;
                        } else {
                                status = WEXITSTATUS(status);