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/*
* The public APIs of the pam-afs-session PAM module.
*
* Provides the public pam_sm_setcred, pam_sm_open_session, and
* pam_sm_close_session functions, plus whatever other stubs we need to
* satisfy PAM.
*
* Written by Russ Allbery <rra@stanford.edu>
* Copyright 2006, 2007, 2008, 2010
* The Board of Trustees of the Leland Stanford Junior University
*
* See LICENSE for licensing terms.
*/
#include <config.h>
#include <portable/kafs.h>
#include <portable/pam.h>
#include <portable/system.h>
#include <errno.h>
#include <internal.h>
#include <pam-util/args.h>
#include <pam-util/logging.h>
/*
* Open a new session. Create a new PAG with k_setpag and then fork the aklog
* binary as the user. A Kerberos v5 PAM module should have previously run to
* obtain Kerberos tickets (or ticket forwarding should have already
* happened).
*/
int
pam_sm_open_session(pam_handle_t *pamh, int flags, int argc,
const char *argv[])
{
struct pam_args *args;
int pamret = PAM_SUCCESS;
const void *dummy;
args = pamafs_init(pamh, flags, argc, argv);
if (args == NULL) {
pamret = PAM_SESSION_ERR;
goto done;
}
ENTRY(args, flags);
/* Do nothing unless AFS is available. */
if (!k_hasafs()) {
putil_err(args, "skipping, AFS apparently not available");
pamret = PAM_IGNORE;
goto done;
}
/*
* Unless nopag is set or we've already created a PAG, always create a
* PAG. Do this even if we're otherwise ignoring the user.
*/
if (pam_get_data(pamh, "pam_afs_session", &dummy) == PAM_SUCCESS) {
if (!k_haspag() && !args->config->nopag)
putil_notice(args, "PAG apparently lost, recreating");
else {
putil_debug(args, "skipping, apparently already ran");
pamret = PAM_SUCCESS;
goto done;
}
}
if (!args->config->nopag && k_setpag() != 0) {
putil_err(args, "PAG creation failed: %s", strerror(errno));
pamret = PAM_SESSION_ERR;
goto done;
}
/* Get tokens. */
if (!args->config->notokens)
pamret = pamafs_token_get(args);
/* Error codes are returned for pam_setcred. Map to pam_open_sesssion. */
if (pamret != PAM_SUCCESS && pamret != PAM_IGNORE)
pamret = PAM_SESSION_ERR;
done:
EXIT(args, pamret);
pamafs_free(args);
return pamret;
}
/*
* Don't do anything for authenticate. We're only an auth module so that we
* can supply a pam_setcred implementation.
*/
int
pam_sm_authenticate(pam_handle_t *pamh UNUSED, int flags UNUSED,
int argc UNUSED, const char *argv[] UNUSED)
{
/*
* We want to return PAM_IGNORE here, but Linux PAM 0.99.7.1 (at least)
* has a bug that causes PAM_IGNORE to result in authentication failure
* when the module is marked [default=done]. So we return PAM_SUCCESS,
* which is dangerous but works in that case.
*/
return PAM_SUCCESS;
}
/*
* Calling pam_setcred with PAM_ESTABLISH_CRED is equivalent to opening a new
* session for our purposes. With PAM_REFRESH_CRED, we don't call setpag,
* just run aklog again. PAM_DELETE_CRED calls unlog.
*/
int
pam_sm_setcred(pam_handle_t *pamh, int flags, int argc,
const char *argv[])
{
struct pam_args *args;
int status;
int pamret = PAM_SUCCESS;
const void *dummy;
args = pamafs_init(pamh, flags, argc, argv);
if (args == NULL) {
pamret = PAM_CRED_ERR;
goto done;
}
ENTRY(args, flags);
/*
* Do nothing unless AFS is available. We need to return success here
* rather than PAM_IGNORE (which would be the more correct return status)
* since PAM_IGNORE can confuse the Linux PAM library, at least for
* applications that call pam_setcred without pam_authenticate (possibly
* because authentication was done some other way), when used with jumps
* with the [] syntax. Since we do nothing in this case, and since the
* stack is already frozen from the auth group, success makes sense.
*/
if (!k_hasafs()) {
putil_err(args, "skipping, AFS apparently not available");
pamret = PAM_SUCCESS;
goto done;
}
/*
* If DELETE_CRED was specified, delete the tokens (if any). Similarly
* return PAM_SUCCESS here instead of PAM_IGNORE. Map the error code for
* pam_setcred, since normally this call is made by pam_close_session.
*/
if (flags & PAM_DELETE_CRED) {
if (args->config->retain_after_close || args->config->notokens) {
pamret = PAM_SUCCESS;
putil_debug(args, "skipping as configured");
} else {
pamret = pamafs_token_delete(args);
if (pamret == PAM_SESSION_ERR)
pamret = PAM_CRED_ERR;
}
goto done;
}
/*
* We're acquiring tokens. See if we already have done this and don't do
* it again if we have unless we were explicitly told to reinitialize. If
* we're reinitializing, we may be running in a screen saver or the like
* and should use the existing PAG, so don't create a new PAG.
*/
if (!(flags & (PAM_REINITIALIZE_CRED | PAM_REFRESH_CRED))) {
status = pam_get_data(pamh, "pam_afs_session", &dummy);
if (status == PAM_SUCCESS) {
if (!k_haspag() && !args->config->nopag)
putil_notice(args, "PAG apparently lost, recreating");
else {
putil_debug(args, "skipping, apparently already ran");
goto done;
}
}
if (!args->config->nopag && k_setpag() != 0) {
putil_err(args, "PAG creation failed: %s", strerror(errno));
pamret = PAM_CRED_ERR;
goto done;
}
}
if (!args->config->notokens)
pamret = pamafs_token_get(args);
done:
EXIT(args, pamret);
pamafs_free(args);
return pamret;
}
/*
* Close a session. Normally, what we do here is call unlog, but we can be
* configured not to do so.
*/
int
pam_sm_close_session(pam_handle_t *pamh, int flags, int argc,
const char *argv[])
{
struct pam_args *args;
int pamret = PAM_SUCCESS;
args = pamafs_init(pamh, flags, argc, argv);
if (args == NULL) {
pamret = PAM_SESSION_ERR;
goto done;
}
ENTRY(args, flags);
/* Do nothing if so configured. */
if (args->config->retain_after_close || args->config->notokens) {
pamret = PAM_IGNORE;
putil_debug(args, "skipping as configured");
goto done;
}
/* Do nothing unless AFS is available. */
if (!k_hasafs()) {
pamret = PAM_IGNORE;
putil_err(args, "skipping, AFS apparently not available");
goto done;
}
/* Delete tokens. */
pamret = pamafs_token_delete(args);
done:
EXIT(args, pamret);
pamafs_free(args);
return pamret;
}
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