From 53a20abf8666d4af2522bd51bf64e9e3c2deb0cf Mon Sep 17 00:00:00 2001 From: Thorsten Kukuk Date: Wed, 3 Sep 2008 13:06:22 +0000 Subject: Relevant BUGIDs: Purpose of commit: new feature Commit summary: --------------- 2008-09-03 Thorsten Kukuk * modules/pam_exec/pam_exec.c: Expose authtok if requested, provide environment variable containing service type. * modules/pam_exec/pam_exec.8.xml: Document new option. --- modules/pam_exec/pam_exec.8.xml | 23 +++++- modules/pam_exec/pam_exec.c | 162 ++++++++++++++++++++++++++++++++++------ 2 files changed, 160 insertions(+), 25 deletions(-) (limited to 'modules/pam_exec') diff --git a/modules/pam_exec/pam_exec.8.xml b/modules/pam_exec/pam_exec.8.xml index 1ee25cab..3cbd6af3 100644 --- a/modules/pam_exec/pam_exec.8.xml +++ b/modules/pam_exec/pam_exec.8.xml @@ -21,6 +21,9 @@ debug + + expose_authtok + seteuid @@ -57,7 +60,11 @@ In addition, the following PAM items are exported as environment variables: PAM_RHOST, PAM_RUSER, PAM_SERVICE, - PAM_TTY, and PAM_USER. + PAM_TTY, PAM_USER and + PAM_TYPE, which contains one of the module + types: , , + , and + . @@ -79,6 +86,20 @@ + + + + + + + During authentication the calling command can read + the password from + stdin3 + . + + + + diff --git a/modules/pam_exec/pam_exec.c b/modules/pam_exec/pam_exec.c index dce65730..47e1d5bb 100644 --- a/modules/pam_exec/pam_exec.c +++ b/modules/pam_exec/pam_exec.c @@ -58,6 +58,7 @@ #include #include #include +#include #define ENV_ITEM(n) { (n), #n } static struct { @@ -71,15 +72,20 @@ static struct { ENV_ITEM(PAM_RUSER), }; + static int -call_exec (pam_handle_t *pamh, int argc, const char **argv) +call_exec (const char *pam_type, pam_handle_t *pamh, + int argc, const char **argv) { int debug = 0; int call_setuid = 0; int quiet = 0; + int expose_authtok = 0; int optargc; const char *logfile = NULL; + const char *authtok = NULL; pid_t pid; + int fds[2]; if (argc < 1) { pam_syslog (pamh, LOG_ERR, @@ -100,10 +106,63 @@ call_exec (pam_handle_t *pamh, int argc, const char **argv) call_setuid = 1; else if (strcasecmp (argv[optargc], "quiet") == 0) quiet = 1; + else if (strcasecmp (argv[optargc], "expose_authtok") == 0) + expose_authtok = 1; else break; /* Unknown option, assume program to execute. */ } + if (expose_authtok == 1) + { + if (strcmp (pam_type, "auth") != 0) + { + pam_syslog (pamh, LOG_ERR, + "expose_authtok not supported for type %s", pam_type); + expose_authtok = 0; + } + else + { + const void *void_pass; + int retval; + + retval = pam_get_item (pamh, PAM_AUTHTOK, &void_pass); + if (retval != PAM_SUCCESS) + { + if (debug) + pam_syslog (pamh, LOG_DEBUG, + "pam_get_item (PAM_AUTHTOK) failed, return %d", + retval); + return retval; + } + else if (void_pass == NULL) + { + char *resp = NULL; + + retval = pam_prompt (pamh, PAM_PROMPT_ECHO_OFF, + &resp, _("Password: ")); + + if (retval != PAM_SUCCESS) + { + _pam_drop (resp); + if (retval == PAM_CONV_AGAIN) + retval = PAM_INCOMPLETE; + return retval; + } + + pam_set_item (pamh, PAM_AUTHTOK, resp); + authtok = strdupa (resp); + _pam_drop (resp); + } + else + authtok = void_pass; + + if (pipe(fds) != 0) + { + pam_syslog (pamh, LOG_ERR, "Could not create pipe: %m"); + return PAM_SYSTEM_ERR; + } + } + } if (optargc >= argc) { pam_syslog (pamh, LOG_ERR, "No path given as argument"); @@ -118,6 +177,27 @@ call_exec (pam_handle_t *pamh, int argc, const char **argv) int status = 0; pid_t retval; + if (expose_authtok) /* send the password to the child */ + { + if (authtok != NULL) + { /* send the password to the child */ + if (debug) + pam_syslog (pamh, LOG_DEBUG, "send password to child"); + if (write(fds[1], authtok, strlen(authtok)+1) == -1) + pam_syslog (pamh, LOG_ERR, + "sending password to child failed: %m"); + authtok = NULL; + } + else + { + if (write(fds[1], "", 1) == -1) /* blank password */ + pam_syslog (pamh, LOG_ERR, + "sending password to child failed: %m"); + } + close(fds[0]); /* close here to avoid possible SIGPIPE above */ + close(fds[1]); + } + while ((retval = waitpid (pid, &status, 0)) == -1 && errno == EINTR); if (retval == (pid_t)-1) @@ -163,17 +243,38 @@ call_exec (pam_handle_t *pamh, int argc, const char **argv) int i; char **envlist, **tmp; int envlen, nitems; + char *envstr; - for (i = 0; i < sysconf (_SC_OPEN_MAX); i++) - close (i); + if (expose_authtok) + { + /* reopen stdin as pipe */ + if (dup2(fds[0], STDIN_FILENO) == -1) + { + int err = errno; + pam_syslog (pamh, LOG_ERR, "dup2 of STDIN failed: %m"); + exit (err); + } - /* New stdin. */ - if ((i = open ("/dev/null", O_RDWR)) < 0) + for (i = 0; i < sysconf (_SC_OPEN_MAX); i++) + { + if (i != STDIN_FILENO) + close (i); + } + } + else { - int err = errno; - pam_syslog (pamh, LOG_ERR, "open of /dev/null failed: %m"); - exit (err); + for (i = 0; i < sysconf (_SC_OPEN_MAX); i++) + close (i); + + /* New stdin. */ + if ((i = open ("/dev/null", O_RDWR)) < 0) + { + int err = errno; + pam_syslog (pamh, LOG_ERR, "open of /dev/null failed: %m"); + exit (err); + } } + /* New stdout and stderr. */ if (logfile) { @@ -195,18 +296,22 @@ call_exec (pam_handle_t *pamh, int argc, const char **argv) } } else - if (dup (i) == -1) - { - int err = errno; - pam_syslog (pamh, LOG_ERR, "dup failed: %m"); - exit (err); - } + { + /* New stdout/stderr. */ + if ((i = open ("/dev/null", O_RDWR)) < 0) + { + int err = errno; + pam_syslog (pamh, LOG_ERR, "open of /dev/null failed: %m"); + exit (err); + } + } + if (dup (i) == -1) - { + { int err = errno; pam_syslog (pamh, LOG_ERR, "dup failed: %m"); - exit (err); - } + exit (err); + } if (call_setuid) if (setuid (geteuid ()) == -1) @@ -240,7 +345,8 @@ call_exec (pam_handle_t *pamh, int argc, const char **argv) for (envlen = 0; envlist[envlen] != NULL; ++envlen) /* nothing */ ; nitems = sizeof(env_items) / sizeof(*env_items); - tmp = realloc(envlist, (envlen + nitems + 1) * sizeof(*envlist)); + /* + 2 because of PAM_TYPE and NULL entry */ + tmp = realloc(envlist, (envlen + nitems + 2) * sizeof(*envlist)); if (tmp == NULL) { free(envlist); @@ -251,7 +357,6 @@ call_exec (pam_handle_t *pamh, int argc, const char **argv) for (i = 0; i < nitems; ++i) { const void *item; - char *envstr; if (pam_get_item(pamh, env_items[i].item, &item) != PAM_SUCCESS || item == NULL) continue; @@ -265,6 +370,15 @@ call_exec (pam_handle_t *pamh, int argc, const char **argv) envlist[envlen] = NULL; } + if (asprintf(&envstr, "PAM_TYPE=%s", pam_type) < 0) + { + free(envlist); + pam_syslog (pamh, LOG_ERR, "prepare environment failed: %m"); + exit (ENOMEM); + } + envlist[envlen++] = envstr; + envlist[envlen] = NULL; + if (debug) pam_syslog (pamh, LOG_DEBUG, "Calling %s ...", arggv[0]); @@ -286,7 +400,7 @@ PAM_EXTERN int pam_sm_authenticate (pam_handle_t *pamh, int flags UNUSED, int argc, const char **argv) { - return call_exec (pamh, argc, argv); + return call_exec ("auth", pamh, argc, argv); } PAM_EXTERN int @@ -304,28 +418,28 @@ pam_sm_chauthtok(pam_handle_t *pamh, int flags, { if (flags & PAM_PRELIM_CHECK) return PAM_SUCCESS; - return call_exec (pamh, argc, argv); + return call_exec ("password", pamh, argc, argv); } PAM_EXTERN int pam_sm_acct_mgmt(pam_handle_t *pamh, int flags UNUSED, int argc, const char **argv) { - return call_exec (pamh, argc, argv); + return call_exec ("account", pamh, argc, argv); } PAM_EXTERN int pam_sm_open_session(pam_handle_t *pamh, int flags UNUSED, int argc, const char **argv) { - return call_exec (pamh, argc, argv); + return call_exec ("open_session", pamh, argc, argv); } PAM_EXTERN int pam_sm_close_session(pam_handle_t *pamh, int flags UNUSED, int argc, const char **argv) { - return call_exec (pamh, argc, argv); + return call_exec ("close_session", pamh, argc, argv); } #ifdef PAM_STATIC -- cgit v1.2.3