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/*
* Manage context structure.
*
* The context structure is the internal state maintained by the pam-krb5
* module between calls to the various public interfaces.
*
* Copyright 2011
* The Board of Trustees of the Leland Stanford Junior University
* Copyright 2005, 2006, 2007, 2008, 2009 Russ Allbery <rra@stanford.edu>
* Copyright 2005 Andres Salomon <dilinger@debian.org>
* Copyright 1999, 2000 Frank Cusack <fcusack@fcusack.com>
*
* See LICENSE for licensing terms.
*/
#include <config.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>
/*
* Create a new context and populate it with the user from PAM and the current
* Kerberos context. Set the default realm if one was configured.
*/
int
pamk5_context_new(struct pam_args *args)
{
struct context *ctx;
int retval;
PAM_CONST char *name;
ctx = calloc(1, sizeof(struct context));
if (ctx == NULL) {
retval = PAM_BUF_ERR;
goto done;
}
ctx->cache = NULL;
ctx->princ = NULL;
ctx->creds = NULL;
ctx->fast_cache = NULL;
ctx->context = args->ctx;
args->config->ctx = ctx;
/*
* This will prompt for the username if it's not already set (generally it
* will be). Otherwise, grab the saved username.
*/
retval = pam_get_user(args->pamh, &name, NULL);
if (retval != PAM_SUCCESS || name == NULL) {
if (retval == PAM_CONV_AGAIN)
retval = PAM_INCOMPLETE;
else
retval = PAM_SERVICE_ERR;
goto done;
}
ctx->name = strdup(name);
args->user = ctx->name;
/* Set a default realm if one was configured. */
if (args->realm != NULL) {
retval = krb5_set_default_realm(ctx->context, args->realm);
if (retval != 0) {
putil_err_krb5(args, retval, "cannot set default realm");
retval = PAM_SERVICE_ERR;
goto done;
}
}
done:
if (ctx != NULL && retval != PAM_SUCCESS)
pamk5_context_free(args);
return retval;
}
/*
* Retrieve a context from the PAM data structures, returning failure if no
* context was present. Note that OpenSSH loses contexts between authenticate
* and setcred, so failure shouldn't always be fatal.
*/
int
pamk5_context_fetch(struct pam_args *args)
{
int pamret;
pamret = pam_get_data(args->pamh, "pam_krb5", (void *) &args->config->ctx);
if (pamret != PAM_SUCCESS)
args->config->ctx = NULL;
if (pamret == 0 && args->config->ctx == NULL)
return PAM_SERVICE_ERR;
if (args->config->ctx != NULL)
args->user = args->config->ctx->name;
return pamret;
}
/*
* Free a context and all of the data that's stored in it. Normally this also
* includes destroying the ticket cache, but don't do this (just close it) if
* a flag was set to preserve it.
*
* This function is common code between pamk5_context_free (called internally
* by our code) and pamk5_context_destroy (called by PAM as a data callback).
*/
static void
context_free(struct context *ctx, bool free_context)
{
if (ctx == NULL)
return;
if (ctx->name != NULL)
free(ctx->name);
if (ctx->context != NULL) {
if (ctx->princ != NULL)
krb5_free_principal(ctx->context, ctx->princ);
if (ctx->cache != NULL) {
if (ctx->dont_destroy_cache)
krb5_cc_close(ctx->context, ctx->cache);
else
krb5_cc_destroy(ctx->context, ctx->cache);
}
if (ctx->creds != NULL) {
krb5_free_cred_contents(ctx->context, ctx->creds);
free(ctx->creds);
}
if (free_context)
krb5_free_context(ctx->context);
}
if (ctx->fast_cache != NULL)
krb5_cc_destroy(ctx->context, ctx->fast_cache);
free(ctx);
}
/*
* Free the current context, used internally by pam-krb5 code. This is a
* wrapper around context_free that makes sure we don't destroy the Kerberos
* context if it's the same as the top-level context and handles other
* bookkeeping in the top-level pam_args struct.
*/
void
pamk5_context_free(struct pam_args *args)
{
if (args->config->ctx == NULL)
return;
if (args->user == args->config->ctx->name)
args->user = NULL;
context_free(args->config->ctx, args->ctx != args->config->ctx->context);
args->config->ctx = NULL;
}
/*
* The PAM callback to destroy the context stored in the PAM data structures.
* Just does the necessary conversion of arguments and calls context_free.
*/
void
pamk5_context_destroy(pam_handle_t *pamh UNUSED, void *data,
int pam_end_status UNUSED)
{
struct context *ctx = (struct context *) data;
if (ctx != NULL)
context_free(ctx, true);
}
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