diff options
Diffstat (limited to 'examples/xsh.c')
| -rw-r--r-- | examples/xsh.c | 173 |
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); +} |