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Diffstat (limited to 'nscd/selinux.c')
| -rw-r--r-- | nscd/selinux.c | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/nscd/selinux.c b/nscd/selinux.c new file mode 100644 index 0000000..0f975f7 --- /dev/null +++ b/nscd/selinux.c @@ -0,0 +1,266 @@ +/* SELinux access controls for nscd. + Copyright (C) 2004 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Matthew Rickard <mjricka@epoch.ncsc.mil>, 2004. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <error.h> +#include <errno.h> +#include <libintl.h> +#include <pthread.h> +#include <stdarg.h> +#include <stdio.h> +#include <stdlib.h> +#include <syslog.h> +#include <selinux/av_permissions.h> +#include <selinux/avc.h> +#include <selinux/flask.h> +#include <selinux/selinux.h> + +#include "dbg_log.h" +#include "selinux.h" + + +#ifdef HAVE_SELINUX +/* Global variable to tell if the kernel has SELinux support. */ +int selinux_enabled; + +/* Define mappings of access vector permissions to request types. */ +static const int perms[LASTREQ] = +{ + [GETPWBYNAME] = NSCD__GETPWD, + [GETPWBYUID] = NSCD__GETPWD, + [GETGRBYNAME] = NSCD__GETGRP, + [GETGRBYGID] = NSCD__GETGRP, + [GETHOSTBYNAME] = NSCD__GETHOST, + [GETHOSTBYNAMEv6] = NSCD__GETHOST, + [GETHOSTBYADDR] = NSCD__GETHOST, + [GETHOSTBYADDRv6] = NSCD__GETHOST, + [GETSTAT] = NSCD__GETSTAT, + [SHUTDOWN] = NSCD__ADMIN, + [INVALIDATE] = NSCD__ADMIN, + [GETFDPW] = NSCD__SHMEMPWD, + [GETFDGR] = NSCD__SHMEMGRP, + [GETFDHST] = NSCD__SHMEMHOST, + [GETAI] = NSCD__GETHOST +}; + +/* Store an entry ref to speed AVC decisions. */ +static struct avc_entry_ref aeref; + +/* Thread to listen for SELinux status changes via netlink. */ +static pthread_t avc_notify_thread; + +/* Prototypes for AVC callback functions. */ +static void *avc_create_thread (void (*run) (void)); +static void avc_stop_thread (void *thread); +static void *avc_alloc_lock (void); +static void avc_get_lock (void *lock); +static void avc_release_lock (void *lock); +static void avc_free_lock (void *lock); + +/* AVC callback structures for use in avc_init. */ +static const struct avc_log_callback log_cb = +{ + .func_log = dbg_log, + .func_audit = NULL +}; +static const struct avc_thread_callback thread_cb = +{ + .func_create_thread = avc_create_thread, + .func_stop_thread = avc_stop_thread +}; +static const struct avc_lock_callback lock_cb = +{ + .func_alloc_lock = avc_alloc_lock, + .func_get_lock = avc_get_lock, + .func_release_lock = avc_release_lock, + .func_free_lock = avc_free_lock +}; + + +/* Determine if we are running on an SELinux kernel. Set selinux_enabled + to the result. */ +void +nscd_selinux_enabled (int *selinux_enabled) +{ + *selinux_enabled = is_selinux_enabled (); + if (*selinux_enabled < 0) + { + dbg_log (_("Failed to determine if kernel supports SELinux")); + exit (EXIT_FAILURE); + } +} + + +/* Create thread for AVC netlink notification. */ +static void * +avc_create_thread (void (*run) (void)) +{ + int rc; + + rc = + pthread_create (&avc_notify_thread, NULL, (void *(*) (void *)) run, NULL); + if (rc != 0) + error (EXIT_FAILURE, rc, _("Failed to start AVC thread")); + + return &avc_notify_thread; +} + + +/* Stop AVC netlink thread. */ +static void +avc_stop_thread (void *thread) +{ + pthread_cancel (*(pthread_t *) thread); +} + + +/* Allocate a new AVC lock. */ +static void * +avc_alloc_lock (void) +{ + pthread_mutex_t *avc_mutex; + + avc_mutex = malloc (sizeof (pthread_mutex_t)); + if (avc_mutex == NULL) + error (EXIT_FAILURE, errno, _("Failed to create AVC lock")); + pthread_mutex_init (avc_mutex, NULL); + + return avc_mutex; +} + + +/* Acquire an AVC lock. */ +static void +avc_get_lock (void *lock) +{ + pthread_mutex_lock (lock); +} + + +/* Release an AVC lock. */ +static void +avc_release_lock (void *lock) +{ + pthread_mutex_unlock (lock); +} + + +/* Free an AVC lock. */ +static void +avc_free_lock (void *lock) +{ + pthread_mutex_destroy (lock); + free (lock); +} + + +/* Initialize the user space access vector cache (AVC) for NSCD along with + log/thread/lock callbacks. */ +void +nscd_avc_init (void) +{ + avc_entry_ref_init (&aeref); + + if (avc_init ("avc", NULL, &log_cb, &thread_cb, &lock_cb) < 0) + error (EXIT_FAILURE, errno, _("Failed to start AVC")); + else + dbg_log (_("Access Vector Cache (AVC) started")); +} + + +/* Check the permission from the caller (via getpeercon) to nscd. + Returns 0 if access is allowed, 1 if denied, and -1 on error. */ +int +nscd_request_avc_has_perm (int fd, request_type req) +{ + /* Initialize to NULL so we know what to free in case of failure. */ + security_context_t scon = NULL; + security_context_t tcon = NULL; + security_id_t ssid = NULL; + security_id_t tsid = NULL; + int rc = -1; + + if (getpeercon (fd, &scon) < 0) + { + dbg_log (_("Error getting context of socket peer")); + goto out; + } + if (getcon (&tcon) < 0) + { + dbg_log (_("Error getting context of nscd")); + goto out; + } + if (avc_context_to_sid (scon, &ssid) < 0 || + avc_context_to_sid (tcon, &tsid) < 0) + { + dbg_log (_("Error getting sid from context")); + goto out; + } + + rc = avc_has_perm (ssid, tsid, SECCLASS_NSCD, perms[req], &aeref, NULL) < 0; + +out: + if (scon) + freecon (scon); + if (tcon) + freecon (tcon); + if (ssid) + sidput (ssid); + if (tsid) + sidput (tsid); + + return rc; +} + + +/* Wrapper to get AVC statistics. */ +void +nscd_avc_cache_stats (struct avc_cache_stats *cstats) +{ + avc_cache_stats (cstats); +} + + +/* Print the AVC statistics to stdout. */ +void +nscd_avc_print_stats (struct avc_cache_stats *cstats) +{ + printf (_("\nSELinux AVC Statistics:\n\n" + "%15u entry lookups\n" + "%15u entry hits\n" + "%15u entry misses\n" + "%15u entry discards\n" + "%15u CAV lookups\n" + "%15u CAV hits\n" + "%15u CAV probes\n" + "%15u CAV misses\n"), + cstats->entry_lookups, cstats->entry_hits, cstats->entry_misses, + cstats->entry_discards, cstats->cav_lookups, cstats->cav_hits, + cstats->cav_probes, cstats->cav_misses); +} + + +/* Clean up the AVC before exiting. */ +void +nscd_avc_destroy (void) +{ + avc_destroy (); +} + +#endif /* HAVE_SELINUX */ |