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-rw-r--r--examples/xsh.c173
1 files changed, 173 insertions, 0 deletions
diff --git a/examples/xsh.c b/examples/xsh.c
new file mode 100644
index 0000000..ef4dca0
--- /dev/null
+++ b/examples/xsh.c
@@ -0,0 +1,173 @@
+/* Andrew Morgan (morgan@kernel.org) -- an example application
+ * that invokes a shell, based on blank.c */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <security/pam_appl.h>
+#include <security/pam_misc.h>
+
+#include <pwd.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/* ------ some local (static) functions ------- */
+
+static void bail_out(pam_handle_t *pamh,int really, int code, const char *fn)
+{
+ fprintf(stderr,"==> called %s()\n got: `%s'\n", fn,
+ pam_strerror(pamh,code));
+ if (really && code)
+ exit (1);
+}
+
+/* ------ some static data objects ------- */
+
+static struct pam_conv conv = {
+ misc_conv,
+ NULL
+};
+
+/* ------- the application itself -------- */
+
+int main(int argc, char **argv)
+{
+ pam_handle_t *pamh=NULL;
+ const void *username=NULL;
+ const char *service="xsh";
+ int retcode;
+
+ /* did the user call with a username as an argument ?
+ * did they also */
+
+ if (argc > 3) {
+ fprintf(stderr,"usage: %s [username [service-name]]\n",argv[0]);
+ }
+ if ((argc >= 2) && (argv[1][0] != '-')) {
+ username = argv[1];
+ }
+ if (argc == 3) {
+ service = argv[2];
+ }
+
+ /* initialize the Linux-PAM library */
+ retcode = pam_start(service, username, &conv, &pamh);
+ bail_out(pamh,1,retcode,"pam_start");
+
+ /* fill in the RUSER and RHOST etc. fields */
+ {
+ char buffer[100];
+ struct passwd *pw;
+ const char *tty;
+
+ pw = getpwuid(getuid());
+ if (pw != NULL) {
+ retcode = pam_set_item(pamh, PAM_RUSER, pw->pw_name);
+ bail_out(pamh,1,retcode,"pam_set_item(PAM_RUSER)");
+ }
+
+ retcode = gethostname(buffer, sizeof(buffer)-1);
+ if (retcode) {
+ perror("failed to look up hostname");
+ retcode = pam_end(pamh, PAM_ABORT);
+ bail_out(pamh,1,retcode,"pam_end");
+ }
+ retcode = pam_set_item(pamh, PAM_RHOST, buffer);
+ bail_out(pamh,1,retcode,"pam_set_item(PAM_RHOST)");
+
+ tty = ttyname(fileno(stdin));
+ if (tty) {
+ retcode = pam_set_item(pamh, PAM_TTY, tty);
+ bail_out(pamh,1,retcode,"pam_set_item(PAM_RHOST)");
+ }
+ }
+
+ /* to avoid using goto we abuse a loop here */
+ for (;;) {
+ /* authenticate the user --- `0' here, could have been PAM_SILENT
+ * | PAM_DISALLOW_NULL_AUTHTOK */
+
+ retcode = pam_authenticate(pamh, 0);
+ bail_out(pamh,0,retcode,"pam_authenticate");
+
+ /* has the user proved themself valid? */
+ if (retcode != PAM_SUCCESS) {
+ fprintf(stderr,"%s: invalid request\n",argv[0]);
+ break;
+ }
+
+ /* the user is valid, but should they have access at this
+ time? */
+
+ retcode = pam_acct_mgmt(pamh, 0); /* `0' could be as above */
+ bail_out(pamh,0,retcode,"pam_acct_mgmt");
+
+ if (retcode == PAM_NEW_AUTHTOK_REQD) {
+ fprintf(stderr,"Application must request new password...\n");
+ retcode = pam_chauthtok(pamh,PAM_CHANGE_EXPIRED_AUTHTOK);
+ bail_out(pamh,0,retcode,"pam_chauthtok");
+ }
+
+ if (retcode != PAM_SUCCESS) {
+ fprintf(stderr,"%s: invalid request\n",argv[0]);
+ break;
+ }
+
+ /* `0' could be as above */
+ retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED);
+ bail_out(pamh,0,retcode,"pam_setcred");
+
+ if (retcode != PAM_SUCCESS) {
+ fprintf(stderr,"%s: problem setting user credentials\n"
+ ,argv[0]);
+ break;
+ }
+
+ /* open a session for the user --- `0' could be PAM_SILENT */
+ retcode = pam_open_session(pamh,0);
+ bail_out(pamh,0,retcode,"pam_open_session");
+ if (retcode != PAM_SUCCESS) {
+ fprintf(stderr,"%s: problem opening a session\n",argv[0]);
+ break;
+ }
+
+ pam_get_item(pamh, PAM_USER, &username);
+ fprintf(stderr,
+ "The user [%s] has been authenticated and `logged in'\n",
+ (const char *)username);
+
+ /* this is always a really bad thing for security! */
+ retcode = system("/bin/sh");
+
+ /* close a session for the user --- `0' could be PAM_SILENT
+ * it is possible that this pam_close_call is in another program..
+ */
+
+ retcode = pam_close_session(pamh,0);
+ bail_out(pamh,0,retcode,"pam_close_session");
+ if (retcode != PAM_SUCCESS) {
+ fprintf(stderr,"%s: problem closing a session\n",argv[0]);
+ break;
+ }
+
+ /* `0' could be as above */
+ retcode = pam_setcred(pamh, PAM_DELETE_CRED);
+ bail_out(pamh,0,retcode,"pam_setcred");
+ if (retcode != PAM_SUCCESS) {
+ fprintf(stderr,"%s: problem deleting user credentials\n"
+ ,argv[0]);
+ break;
+ }
+
+ break; /* don't go on for ever! */
+ }
+
+ /* close the Linux-PAM library */
+ retcode = pam_end(pamh, PAM_SUCCESS);
+ pamh = NULL;
+ bail_out(pamh,1,retcode,"pam_end");
+
+ return (0);
+}