![peter enderborg](/assets/img/avatar_default.png)
Replace printk with pr_* to avoid checkpatch warnings. Signed-off-by: Peter Enderborg <peter.enderborg@sony.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
1235 lines
32 KiB
C
1235 lines
32 KiB
C
/*
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* Implementation of the kernel access vector cache (AVC).
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*
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* Authors: Stephen Smalley, <sds@tycho.nsa.gov>
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* James Morris <jmorris@redhat.com>
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*
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* Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
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* Replaced the avc_lock spinlock by RCU.
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*
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* Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2,
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* as published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/stddef.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/dcache.h>
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#include <linux/init.h>
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#include <linux/skbuff.h>
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#include <linux/percpu.h>
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#include <linux/list.h>
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#include <net/sock.h>
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#include <linux/un.h>
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#include <net/af_unix.h>
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#include <linux/ip.h>
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#include <linux/audit.h>
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#include <linux/ipv6.h>
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#include <net/ipv6.h>
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#include "avc.h"
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#include "avc_ss.h"
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#include "classmap.h"
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#define AVC_CACHE_SLOTS 512
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#define AVC_DEF_CACHE_THRESHOLD 512
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#define AVC_CACHE_RECLAIM 16
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#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
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#define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
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#else
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#define avc_cache_stats_incr(field) do {} while (0)
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#endif
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struct avc_entry {
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u32 ssid;
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u32 tsid;
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u16 tclass;
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struct av_decision avd;
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struct avc_xperms_node *xp_node;
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};
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struct avc_node {
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struct avc_entry ae;
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struct hlist_node list; /* anchored in avc_cache->slots[i] */
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struct rcu_head rhead;
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};
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struct avc_xperms_decision_node {
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struct extended_perms_decision xpd;
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struct list_head xpd_list; /* list of extended_perms_decision */
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};
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struct avc_xperms_node {
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struct extended_perms xp;
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struct list_head xpd_head; /* list head of extended_perms_decision */
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};
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struct avc_cache {
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struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
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spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
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atomic_t lru_hint; /* LRU hint for reclaim scan */
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atomic_t active_nodes;
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u32 latest_notif; /* latest revocation notification */
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};
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struct avc_callback_node {
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int (*callback) (u32 event);
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u32 events;
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struct avc_callback_node *next;
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};
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#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
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DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
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#endif
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struct selinux_avc {
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unsigned int avc_cache_threshold;
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struct avc_cache avc_cache;
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};
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static struct selinux_avc selinux_avc;
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void selinux_avc_init(struct selinux_avc **avc)
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{
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int i;
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selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
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for (i = 0; i < AVC_CACHE_SLOTS; i++) {
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INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
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spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
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}
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atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
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atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
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*avc = &selinux_avc;
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}
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unsigned int avc_get_cache_threshold(struct selinux_avc *avc)
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{
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return avc->avc_cache_threshold;
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}
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void avc_set_cache_threshold(struct selinux_avc *avc,
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unsigned int cache_threshold)
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{
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avc->avc_cache_threshold = cache_threshold;
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}
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static struct avc_callback_node *avc_callbacks;
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static struct kmem_cache *avc_node_cachep;
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static struct kmem_cache *avc_xperms_data_cachep;
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static struct kmem_cache *avc_xperms_decision_cachep;
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static struct kmem_cache *avc_xperms_cachep;
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static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
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{
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return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
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}
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/**
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* avc_dump_av - Display an access vector in human-readable form.
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* @tclass: target security class
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* @av: access vector
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*/
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static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
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{
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const char **perms;
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int i, perm;
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if (av == 0) {
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audit_log_format(ab, " null");
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return;
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}
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BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map));
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perms = secclass_map[tclass-1].perms;
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audit_log_format(ab, " {");
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i = 0;
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perm = 1;
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while (i < (sizeof(av) * 8)) {
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if ((perm & av) && perms[i]) {
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audit_log_format(ab, " %s", perms[i]);
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av &= ~perm;
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}
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i++;
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perm <<= 1;
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}
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if (av)
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audit_log_format(ab, " 0x%x", av);
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audit_log_format(ab, " }");
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}
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/**
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* avc_dump_query - Display a SID pair and a class in human-readable form.
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* @ssid: source security identifier
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* @tsid: target security identifier
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* @tclass: target security class
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*/
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static void avc_dump_query(struct audit_buffer *ab, struct selinux_state *state,
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u32 ssid, u32 tsid, u16 tclass)
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{
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int rc;
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char *scontext;
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u32 scontext_len;
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rc = security_sid_to_context(state, ssid, &scontext, &scontext_len);
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if (rc)
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audit_log_format(ab, "ssid=%d", ssid);
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else {
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audit_log_format(ab, "scontext=%s", scontext);
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kfree(scontext);
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}
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rc = security_sid_to_context(state, tsid, &scontext, &scontext_len);
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if (rc)
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audit_log_format(ab, " tsid=%d", tsid);
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else {
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audit_log_format(ab, " tcontext=%s", scontext);
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kfree(scontext);
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}
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BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map));
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audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name);
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}
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/**
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* avc_init - Initialize the AVC.
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*
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* Initialize the access vector cache.
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*/
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void __init avc_init(void)
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{
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avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
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0, SLAB_PANIC, NULL);
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avc_xperms_cachep = kmem_cache_create("avc_xperms_node",
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sizeof(struct avc_xperms_node),
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0, SLAB_PANIC, NULL);
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avc_xperms_decision_cachep = kmem_cache_create(
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"avc_xperms_decision_node",
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sizeof(struct avc_xperms_decision_node),
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0, SLAB_PANIC, NULL);
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avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data",
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sizeof(struct extended_perms_data),
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0, SLAB_PANIC, NULL);
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}
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int avc_get_hash_stats(struct selinux_avc *avc, char *page)
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{
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int i, chain_len, max_chain_len, slots_used;
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struct avc_node *node;
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struct hlist_head *head;
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rcu_read_lock();
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slots_used = 0;
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max_chain_len = 0;
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for (i = 0; i < AVC_CACHE_SLOTS; i++) {
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head = &avc->avc_cache.slots[i];
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if (!hlist_empty(head)) {
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slots_used++;
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chain_len = 0;
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hlist_for_each_entry_rcu(node, head, list)
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chain_len++;
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if (chain_len > max_chain_len)
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max_chain_len = chain_len;
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}
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}
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rcu_read_unlock();
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return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
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"longest chain: %d\n",
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atomic_read(&avc->avc_cache.active_nodes),
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slots_used, AVC_CACHE_SLOTS, max_chain_len);
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}
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/*
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* using a linked list for extended_perms_decision lookup because the list is
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* always small. i.e. less than 5, typically 1
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*/
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static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver,
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struct avc_xperms_node *xp_node)
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{
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struct avc_xperms_decision_node *xpd_node;
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list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
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if (xpd_node->xpd.driver == driver)
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return &xpd_node->xpd;
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}
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return NULL;
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}
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static inline unsigned int
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avc_xperms_has_perm(struct extended_perms_decision *xpd,
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u8 perm, u8 which)
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{
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unsigned int rc = 0;
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if ((which == XPERMS_ALLOWED) &&
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(xpd->used & XPERMS_ALLOWED))
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rc = security_xperm_test(xpd->allowed->p, perm);
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else if ((which == XPERMS_AUDITALLOW) &&
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(xpd->used & XPERMS_AUDITALLOW))
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rc = security_xperm_test(xpd->auditallow->p, perm);
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else if ((which == XPERMS_DONTAUDIT) &&
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(xpd->used & XPERMS_DONTAUDIT))
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rc = security_xperm_test(xpd->dontaudit->p, perm);
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return rc;
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}
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static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
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u8 driver, u8 perm)
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{
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struct extended_perms_decision *xpd;
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security_xperm_set(xp_node->xp.drivers.p, driver);
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xpd = avc_xperms_decision_lookup(driver, xp_node);
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if (xpd && xpd->allowed)
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security_xperm_set(xpd->allowed->p, perm);
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}
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static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
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{
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struct extended_perms_decision *xpd;
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xpd = &xpd_node->xpd;
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if (xpd->allowed)
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kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
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if (xpd->auditallow)
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kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
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if (xpd->dontaudit)
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kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
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kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
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}
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static void avc_xperms_free(struct avc_xperms_node *xp_node)
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{
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struct avc_xperms_decision_node *xpd_node, *tmp;
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if (!xp_node)
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return;
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list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
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list_del(&xpd_node->xpd_list);
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avc_xperms_decision_free(xpd_node);
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}
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kmem_cache_free(avc_xperms_cachep, xp_node);
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}
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static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
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struct extended_perms_decision *src)
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{
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dest->driver = src->driver;
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dest->used = src->used;
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if (dest->used & XPERMS_ALLOWED)
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memcpy(dest->allowed->p, src->allowed->p,
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sizeof(src->allowed->p));
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if (dest->used & XPERMS_AUDITALLOW)
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memcpy(dest->auditallow->p, src->auditallow->p,
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sizeof(src->auditallow->p));
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if (dest->used & XPERMS_DONTAUDIT)
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memcpy(dest->dontaudit->p, src->dontaudit->p,
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sizeof(src->dontaudit->p));
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}
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/*
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* similar to avc_copy_xperms_decision, but only copy decision
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* information relevant to this perm
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*/
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static inline void avc_quick_copy_xperms_decision(u8 perm,
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struct extended_perms_decision *dest,
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struct extended_perms_decision *src)
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{
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/*
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* compute index of the u32 of the 256 bits (8 u32s) that contain this
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* command permission
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*/
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u8 i = perm >> 5;
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dest->used = src->used;
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if (dest->used & XPERMS_ALLOWED)
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dest->allowed->p[i] = src->allowed->p[i];
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if (dest->used & XPERMS_AUDITALLOW)
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dest->auditallow->p[i] = src->auditallow->p[i];
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if (dest->used & XPERMS_DONTAUDIT)
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dest->dontaudit->p[i] = src->dontaudit->p[i];
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}
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static struct avc_xperms_decision_node
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*avc_xperms_decision_alloc(u8 which)
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{
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struct avc_xperms_decision_node *xpd_node;
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struct extended_perms_decision *xpd;
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xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep, GFP_NOWAIT);
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if (!xpd_node)
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return NULL;
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xpd = &xpd_node->xpd;
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if (which & XPERMS_ALLOWED) {
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xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
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GFP_NOWAIT);
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if (!xpd->allowed)
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goto error;
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}
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if (which & XPERMS_AUDITALLOW) {
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xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
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GFP_NOWAIT);
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if (!xpd->auditallow)
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goto error;
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}
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if (which & XPERMS_DONTAUDIT) {
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xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
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GFP_NOWAIT);
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if (!xpd->dontaudit)
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goto error;
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}
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return xpd_node;
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error:
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avc_xperms_decision_free(xpd_node);
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return NULL;
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}
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|
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static int avc_add_xperms_decision(struct avc_node *node,
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struct extended_perms_decision *src)
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{
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struct avc_xperms_decision_node *dest_xpd;
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node->ae.xp_node->xp.len++;
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dest_xpd = avc_xperms_decision_alloc(src->used);
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if (!dest_xpd)
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return -ENOMEM;
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avc_copy_xperms_decision(&dest_xpd->xpd, src);
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list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
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return 0;
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}
|
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|
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static struct avc_xperms_node *avc_xperms_alloc(void)
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{
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struct avc_xperms_node *xp_node;
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|
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xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT);
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if (!xp_node)
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return xp_node;
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INIT_LIST_HEAD(&xp_node->xpd_head);
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return xp_node;
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}
|
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|
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static int avc_xperms_populate(struct avc_node *node,
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struct avc_xperms_node *src)
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{
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struct avc_xperms_node *dest;
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struct avc_xperms_decision_node *dest_xpd;
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struct avc_xperms_decision_node *src_xpd;
|
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|
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if (src->xp.len == 0)
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return 0;
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dest = avc_xperms_alloc();
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if (!dest)
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return -ENOMEM;
|
|
|
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memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
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dest->xp.len = src->xp.len;
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/* for each source xpd allocate a destination xpd and copy */
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list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) {
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dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used);
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if (!dest_xpd)
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goto error;
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avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd);
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list_add(&dest_xpd->xpd_list, &dest->xpd_head);
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}
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node->ae.xp_node = dest;
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return 0;
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error:
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avc_xperms_free(dest);
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return -ENOMEM;
|
|
|
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}
|
|
|
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static inline u32 avc_xperms_audit_required(u32 requested,
|
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struct av_decision *avd,
|
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struct extended_perms_decision *xpd,
|
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u8 perm,
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int result,
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u32 *deniedp)
|
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{
|
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u32 denied, audited;
|
|
|
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denied = requested & ~avd->allowed;
|
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if (unlikely(denied)) {
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audited = denied & avd->auditdeny;
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if (audited && xpd) {
|
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if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
|
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audited &= ~requested;
|
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}
|
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} else if (result) {
|
|
audited = denied = requested;
|
|
} else {
|
|
audited = requested & avd->auditallow;
|
|
if (audited && xpd) {
|
|
if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
|
|
audited &= ~requested;
|
|
}
|
|
}
|
|
|
|
*deniedp = denied;
|
|
return audited;
|
|
}
|
|
|
|
static inline int avc_xperms_audit(struct selinux_state *state,
|
|
u32 ssid, u32 tsid, u16 tclass,
|
|
u32 requested, struct av_decision *avd,
|
|
struct extended_perms_decision *xpd,
|
|
u8 perm, int result,
|
|
struct common_audit_data *ad)
|
|
{
|
|
u32 audited, denied;
|
|
|
|
audited = avc_xperms_audit_required(
|
|
requested, avd, xpd, perm, result, &denied);
|
|
if (likely(!audited))
|
|
return 0;
|
|
return slow_avc_audit(state, ssid, tsid, tclass, requested,
|
|
audited, denied, result, ad, 0);
|
|
}
|
|
|
|
static void avc_node_free(struct rcu_head *rhead)
|
|
{
|
|
struct avc_node *node = container_of(rhead, struct avc_node, rhead);
|
|
avc_xperms_free(node->ae.xp_node);
|
|
kmem_cache_free(avc_node_cachep, node);
|
|
avc_cache_stats_incr(frees);
|
|
}
|
|
|
|
static void avc_node_delete(struct selinux_avc *avc, struct avc_node *node)
|
|
{
|
|
hlist_del_rcu(&node->list);
|
|
call_rcu(&node->rhead, avc_node_free);
|
|
atomic_dec(&avc->avc_cache.active_nodes);
|
|
}
|
|
|
|
static void avc_node_kill(struct selinux_avc *avc, struct avc_node *node)
|
|
{
|
|
avc_xperms_free(node->ae.xp_node);
|
|
kmem_cache_free(avc_node_cachep, node);
|
|
avc_cache_stats_incr(frees);
|
|
atomic_dec(&avc->avc_cache.active_nodes);
|
|
}
|
|
|
|
static void avc_node_replace(struct selinux_avc *avc,
|
|
struct avc_node *new, struct avc_node *old)
|
|
{
|
|
hlist_replace_rcu(&old->list, &new->list);
|
|
call_rcu(&old->rhead, avc_node_free);
|
|
atomic_dec(&avc->avc_cache.active_nodes);
|
|
}
|
|
|
|
static inline int avc_reclaim_node(struct selinux_avc *avc)
|
|
{
|
|
struct avc_node *node;
|
|
int hvalue, try, ecx;
|
|
unsigned long flags;
|
|
struct hlist_head *head;
|
|
spinlock_t *lock;
|
|
|
|
for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
|
|
hvalue = atomic_inc_return(&avc->avc_cache.lru_hint) &
|
|
(AVC_CACHE_SLOTS - 1);
|
|
head = &avc->avc_cache.slots[hvalue];
|
|
lock = &avc->avc_cache.slots_lock[hvalue];
|
|
|
|
if (!spin_trylock_irqsave(lock, flags))
|
|
continue;
|
|
|
|
rcu_read_lock();
|
|
hlist_for_each_entry(node, head, list) {
|
|
avc_node_delete(avc, node);
|
|
avc_cache_stats_incr(reclaims);
|
|
ecx++;
|
|
if (ecx >= AVC_CACHE_RECLAIM) {
|
|
rcu_read_unlock();
|
|
spin_unlock_irqrestore(lock, flags);
|
|
goto out;
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
spin_unlock_irqrestore(lock, flags);
|
|
}
|
|
out:
|
|
return ecx;
|
|
}
|
|
|
|
static struct avc_node *avc_alloc_node(struct selinux_avc *avc)
|
|
{
|
|
struct avc_node *node;
|
|
|
|
node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT);
|
|
if (!node)
|
|
goto out;
|
|
|
|
INIT_HLIST_NODE(&node->list);
|
|
avc_cache_stats_incr(allocations);
|
|
|
|
if (atomic_inc_return(&avc->avc_cache.active_nodes) >
|
|
avc->avc_cache_threshold)
|
|
avc_reclaim_node(avc);
|
|
|
|
out:
|
|
return node;
|
|
}
|
|
|
|
static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
|
|
{
|
|
node->ae.ssid = ssid;
|
|
node->ae.tsid = tsid;
|
|
node->ae.tclass = tclass;
|
|
memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
|
|
}
|
|
|
|
static inline struct avc_node *avc_search_node(struct selinux_avc *avc,
|
|
u32 ssid, u32 tsid, u16 tclass)
|
|
{
|
|
struct avc_node *node, *ret = NULL;
|
|
int hvalue;
|
|
struct hlist_head *head;
|
|
|
|
hvalue = avc_hash(ssid, tsid, tclass);
|
|
head = &avc->avc_cache.slots[hvalue];
|
|
hlist_for_each_entry_rcu(node, head, list) {
|
|
if (ssid == node->ae.ssid &&
|
|
tclass == node->ae.tclass &&
|
|
tsid == node->ae.tsid) {
|
|
ret = node;
|
|
break;
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* avc_lookup - Look up an AVC entry.
|
|
* @ssid: source security identifier
|
|
* @tsid: target security identifier
|
|
* @tclass: target security class
|
|
*
|
|
* Look up an AVC entry that is valid for the
|
|
* (@ssid, @tsid), interpreting the permissions
|
|
* based on @tclass. If a valid AVC entry exists,
|
|
* then this function returns the avc_node.
|
|
* Otherwise, this function returns NULL.
|
|
*/
|
|
static struct avc_node *avc_lookup(struct selinux_avc *avc,
|
|
u32 ssid, u32 tsid, u16 tclass)
|
|
{
|
|
struct avc_node *node;
|
|
|
|
avc_cache_stats_incr(lookups);
|
|
node = avc_search_node(avc, ssid, tsid, tclass);
|
|
|
|
if (node)
|
|
return node;
|
|
|
|
avc_cache_stats_incr(misses);
|
|
return NULL;
|
|
}
|
|
|
|
static int avc_latest_notif_update(struct selinux_avc *avc,
|
|
int seqno, int is_insert)
|
|
{
|
|
int ret = 0;
|
|
static DEFINE_SPINLOCK(notif_lock);
|
|
unsigned long flag;
|
|
|
|
spin_lock_irqsave(¬if_lock, flag);
|
|
if (is_insert) {
|
|
if (seqno < avc->avc_cache.latest_notif) {
|
|
pr_warn("SELinux: avc: seqno %d < latest_notif %d\n",
|
|
seqno, avc->avc_cache.latest_notif);
|
|
ret = -EAGAIN;
|
|
}
|
|
} else {
|
|
if (seqno > avc->avc_cache.latest_notif)
|
|
avc->avc_cache.latest_notif = seqno;
|
|
}
|
|
spin_unlock_irqrestore(¬if_lock, flag);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* avc_insert - Insert an AVC entry.
|
|
* @ssid: source security identifier
|
|
* @tsid: target security identifier
|
|
* @tclass: target security class
|
|
* @avd: resulting av decision
|
|
* @xp_node: resulting extended permissions
|
|
*
|
|
* Insert an AVC entry for the SID pair
|
|
* (@ssid, @tsid) and class @tclass.
|
|
* The access vectors and the sequence number are
|
|
* normally provided by the security server in
|
|
* response to a security_compute_av() call. If the
|
|
* sequence number @avd->seqno is not less than the latest
|
|
* revocation notification, then the function copies
|
|
* the access vectors into a cache entry, returns
|
|
* avc_node inserted. Otherwise, this function returns NULL.
|
|
*/
|
|
static struct avc_node *avc_insert(struct selinux_avc *avc,
|
|
u32 ssid, u32 tsid, u16 tclass,
|
|
struct av_decision *avd,
|
|
struct avc_xperms_node *xp_node)
|
|
{
|
|
struct avc_node *pos, *node = NULL;
|
|
int hvalue;
|
|
unsigned long flag;
|
|
|
|
if (avc_latest_notif_update(avc, avd->seqno, 1))
|
|
goto out;
|
|
|
|
node = avc_alloc_node(avc);
|
|
if (node) {
|
|
struct hlist_head *head;
|
|
spinlock_t *lock;
|
|
int rc = 0;
|
|
|
|
hvalue = avc_hash(ssid, tsid, tclass);
|
|
avc_node_populate(node, ssid, tsid, tclass, avd);
|
|
rc = avc_xperms_populate(node, xp_node);
|
|
if (rc) {
|
|
kmem_cache_free(avc_node_cachep, node);
|
|
return NULL;
|
|
}
|
|
head = &avc->avc_cache.slots[hvalue];
|
|
lock = &avc->avc_cache.slots_lock[hvalue];
|
|
|
|
spin_lock_irqsave(lock, flag);
|
|
hlist_for_each_entry(pos, head, list) {
|
|
if (pos->ae.ssid == ssid &&
|
|
pos->ae.tsid == tsid &&
|
|
pos->ae.tclass == tclass) {
|
|
avc_node_replace(avc, node, pos);
|
|
goto found;
|
|
}
|
|
}
|
|
hlist_add_head_rcu(&node->list, head);
|
|
found:
|
|
spin_unlock_irqrestore(lock, flag);
|
|
}
|
|
out:
|
|
return node;
|
|
}
|
|
|
|
/**
|
|
* avc_audit_pre_callback - SELinux specific information
|
|
* will be called by generic audit code
|
|
* @ab: the audit buffer
|
|
* @a: audit_data
|
|
*/
|
|
static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
|
|
{
|
|
struct common_audit_data *ad = a;
|
|
audit_log_format(ab, "avc: %s ",
|
|
ad->selinux_audit_data->denied ? "denied" : "granted");
|
|
avc_dump_av(ab, ad->selinux_audit_data->tclass,
|
|
ad->selinux_audit_data->audited);
|
|
audit_log_format(ab, " for ");
|
|
}
|
|
|
|
/**
|
|
* avc_audit_post_callback - SELinux specific information
|
|
* will be called by generic audit code
|
|
* @ab: the audit buffer
|
|
* @a: audit_data
|
|
*/
|
|
static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
|
|
{
|
|
struct common_audit_data *ad = a;
|
|
audit_log_format(ab, " ");
|
|
avc_dump_query(ab, ad->selinux_audit_data->state,
|
|
ad->selinux_audit_data->ssid,
|
|
ad->selinux_audit_data->tsid,
|
|
ad->selinux_audit_data->tclass);
|
|
if (ad->selinux_audit_data->denied) {
|
|
audit_log_format(ab, " permissive=%u",
|
|
ad->selinux_audit_data->result ? 0 : 1);
|
|
}
|
|
}
|
|
|
|
/* This is the slow part of avc audit with big stack footprint */
|
|
noinline int slow_avc_audit(struct selinux_state *state,
|
|
u32 ssid, u32 tsid, u16 tclass,
|
|
u32 requested, u32 audited, u32 denied, int result,
|
|
struct common_audit_data *a,
|
|
unsigned int flags)
|
|
{
|
|
struct common_audit_data stack_data;
|
|
struct selinux_audit_data sad;
|
|
|
|
if (!a) {
|
|
a = &stack_data;
|
|
a->type = LSM_AUDIT_DATA_NONE;
|
|
}
|
|
|
|
/*
|
|
* When in a RCU walk do the audit on the RCU retry. This is because
|
|
* the collection of the dname in an inode audit message is not RCU
|
|
* safe. Note this may drop some audits when the situation changes
|
|
* during retry. However this is logically just as if the operation
|
|
* happened a little later.
|
|
*/
|
|
if ((a->type == LSM_AUDIT_DATA_INODE) &&
|
|
(flags & MAY_NOT_BLOCK))
|
|
return -ECHILD;
|
|
|
|
sad.tclass = tclass;
|
|
sad.requested = requested;
|
|
sad.ssid = ssid;
|
|
sad.tsid = tsid;
|
|
sad.audited = audited;
|
|
sad.denied = denied;
|
|
sad.result = result;
|
|
sad.state = state;
|
|
|
|
a->selinux_audit_data = &sad;
|
|
|
|
common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* avc_add_callback - Register a callback for security events.
|
|
* @callback: callback function
|
|
* @events: security events
|
|
*
|
|
* Register a callback function for events in the set @events.
|
|
* Returns %0 on success or -%ENOMEM if insufficient memory
|
|
* exists to add the callback.
|
|
*/
|
|
int __init avc_add_callback(int (*callback)(u32 event), u32 events)
|
|
{
|
|
struct avc_callback_node *c;
|
|
int rc = 0;
|
|
|
|
c = kmalloc(sizeof(*c), GFP_KERNEL);
|
|
if (!c) {
|
|
rc = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
c->callback = callback;
|
|
c->events = events;
|
|
c->next = avc_callbacks;
|
|
avc_callbacks = c;
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* avc_update_node Update an AVC entry
|
|
* @event : Updating event
|
|
* @perms : Permission mask bits
|
|
* @ssid,@tsid,@tclass : identifier of an AVC entry
|
|
* @seqno : sequence number when decision was made
|
|
* @xpd: extended_perms_decision to be added to the node
|
|
*
|
|
* if a valid AVC entry doesn't exist,this function returns -ENOENT.
|
|
* if kmalloc() called internal returns NULL, this function returns -ENOMEM.
|
|
* otherwise, this function updates the AVC entry. The original AVC-entry object
|
|
* will release later by RCU.
|
|
*/
|
|
static int avc_update_node(struct selinux_avc *avc,
|
|
u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
|
|
u32 tsid, u16 tclass, u32 seqno,
|
|
struct extended_perms_decision *xpd,
|
|
u32 flags)
|
|
{
|
|
int hvalue, rc = 0;
|
|
unsigned long flag;
|
|
struct avc_node *pos, *node, *orig = NULL;
|
|
struct hlist_head *head;
|
|
spinlock_t *lock;
|
|
|
|
node = avc_alloc_node(avc);
|
|
if (!node) {
|
|
rc = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
/* Lock the target slot */
|
|
hvalue = avc_hash(ssid, tsid, tclass);
|
|
|
|
head = &avc->avc_cache.slots[hvalue];
|
|
lock = &avc->avc_cache.slots_lock[hvalue];
|
|
|
|
spin_lock_irqsave(lock, flag);
|
|
|
|
hlist_for_each_entry(pos, head, list) {
|
|
if (ssid == pos->ae.ssid &&
|
|
tsid == pos->ae.tsid &&
|
|
tclass == pos->ae.tclass &&
|
|
seqno == pos->ae.avd.seqno){
|
|
orig = pos;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!orig) {
|
|
rc = -ENOENT;
|
|
avc_node_kill(avc, node);
|
|
goto out_unlock;
|
|
}
|
|
|
|
/*
|
|
* Copy and replace original node.
|
|
*/
|
|
|
|
avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
|
|
|
|
if (orig->ae.xp_node) {
|
|
rc = avc_xperms_populate(node, orig->ae.xp_node);
|
|
if (rc) {
|
|
kmem_cache_free(avc_node_cachep, node);
|
|
goto out_unlock;
|
|
}
|
|
}
|
|
|
|
switch (event) {
|
|
case AVC_CALLBACK_GRANT:
|
|
node->ae.avd.allowed |= perms;
|
|
if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
|
|
avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
|
|
break;
|
|
case AVC_CALLBACK_TRY_REVOKE:
|
|
case AVC_CALLBACK_REVOKE:
|
|
node->ae.avd.allowed &= ~perms;
|
|
break;
|
|
case AVC_CALLBACK_AUDITALLOW_ENABLE:
|
|
node->ae.avd.auditallow |= perms;
|
|
break;
|
|
case AVC_CALLBACK_AUDITALLOW_DISABLE:
|
|
node->ae.avd.auditallow &= ~perms;
|
|
break;
|
|
case AVC_CALLBACK_AUDITDENY_ENABLE:
|
|
node->ae.avd.auditdeny |= perms;
|
|
break;
|
|
case AVC_CALLBACK_AUDITDENY_DISABLE:
|
|
node->ae.avd.auditdeny &= ~perms;
|
|
break;
|
|
case AVC_CALLBACK_ADD_XPERMS:
|
|
avc_add_xperms_decision(node, xpd);
|
|
break;
|
|
}
|
|
avc_node_replace(avc, node, orig);
|
|
out_unlock:
|
|
spin_unlock_irqrestore(lock, flag);
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* avc_flush - Flush the cache
|
|
*/
|
|
static void avc_flush(struct selinux_avc *avc)
|
|
{
|
|
struct hlist_head *head;
|
|
struct avc_node *node;
|
|
spinlock_t *lock;
|
|
unsigned long flag;
|
|
int i;
|
|
|
|
for (i = 0; i < AVC_CACHE_SLOTS; i++) {
|
|
head = &avc->avc_cache.slots[i];
|
|
lock = &avc->avc_cache.slots_lock[i];
|
|
|
|
spin_lock_irqsave(lock, flag);
|
|
/*
|
|
* With preemptable RCU, the outer spinlock does not
|
|
* prevent RCU grace periods from ending.
|
|
*/
|
|
rcu_read_lock();
|
|
hlist_for_each_entry(node, head, list)
|
|
avc_node_delete(avc, node);
|
|
rcu_read_unlock();
|
|
spin_unlock_irqrestore(lock, flag);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* avc_ss_reset - Flush the cache and revalidate migrated permissions.
|
|
* @seqno: policy sequence number
|
|
*/
|
|
int avc_ss_reset(struct selinux_avc *avc, u32 seqno)
|
|
{
|
|
struct avc_callback_node *c;
|
|
int rc = 0, tmprc;
|
|
|
|
avc_flush(avc);
|
|
|
|
for (c = avc_callbacks; c; c = c->next) {
|
|
if (c->events & AVC_CALLBACK_RESET) {
|
|
tmprc = c->callback(AVC_CALLBACK_RESET);
|
|
/* save the first error encountered for the return
|
|
value and continue processing the callbacks */
|
|
if (!rc)
|
|
rc = tmprc;
|
|
}
|
|
}
|
|
|
|
avc_latest_notif_update(avc, seqno, 0);
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* Slow-path helper function for avc_has_perm_noaudit,
|
|
* when the avc_node lookup fails. We get called with
|
|
* the RCU read lock held, and need to return with it
|
|
* still held, but drop if for the security compute.
|
|
*
|
|
* Don't inline this, since it's the slow-path and just
|
|
* results in a bigger stack frame.
|
|
*/
|
|
static noinline
|
|
struct avc_node *avc_compute_av(struct selinux_state *state,
|
|
u32 ssid, u32 tsid,
|
|
u16 tclass, struct av_decision *avd,
|
|
struct avc_xperms_node *xp_node)
|
|
{
|
|
rcu_read_unlock();
|
|
INIT_LIST_HEAD(&xp_node->xpd_head);
|
|
security_compute_av(state, ssid, tsid, tclass, avd, &xp_node->xp);
|
|
rcu_read_lock();
|
|
return avc_insert(state->avc, ssid, tsid, tclass, avd, xp_node);
|
|
}
|
|
|
|
static noinline int avc_denied(struct selinux_state *state,
|
|
u32 ssid, u32 tsid,
|
|
u16 tclass, u32 requested,
|
|
u8 driver, u8 xperm, unsigned int flags,
|
|
struct av_decision *avd)
|
|
{
|
|
if (flags & AVC_STRICT)
|
|
return -EACCES;
|
|
|
|
if (enforcing_enabled(state) &&
|
|
!(avd->flags & AVD_FLAGS_PERMISSIVE))
|
|
return -EACCES;
|
|
|
|
avc_update_node(state->avc, AVC_CALLBACK_GRANT, requested, driver,
|
|
xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* The avc extended permissions logic adds an additional 256 bits of
|
|
* permissions to an avc node when extended permissions for that node are
|
|
* specified in the avtab. If the additional 256 permissions is not adequate,
|
|
* as-is the case with ioctls, then multiple may be chained together and the
|
|
* driver field is used to specify which set contains the permission.
|
|
*/
|
|
int avc_has_extended_perms(struct selinux_state *state,
|
|
u32 ssid, u32 tsid, u16 tclass, u32 requested,
|
|
u8 driver, u8 xperm, struct common_audit_data *ad)
|
|
{
|
|
struct avc_node *node;
|
|
struct av_decision avd;
|
|
u32 denied;
|
|
struct extended_perms_decision local_xpd;
|
|
struct extended_perms_decision *xpd = NULL;
|
|
struct extended_perms_data allowed;
|
|
struct extended_perms_data auditallow;
|
|
struct extended_perms_data dontaudit;
|
|
struct avc_xperms_node local_xp_node;
|
|
struct avc_xperms_node *xp_node;
|
|
int rc = 0, rc2;
|
|
|
|
xp_node = &local_xp_node;
|
|
BUG_ON(!requested);
|
|
|
|
rcu_read_lock();
|
|
|
|
node = avc_lookup(state->avc, ssid, tsid, tclass);
|
|
if (unlikely(!node)) {
|
|
node = avc_compute_av(state, ssid, tsid, tclass, &avd, xp_node);
|
|
} else {
|
|
memcpy(&avd, &node->ae.avd, sizeof(avd));
|
|
xp_node = node->ae.xp_node;
|
|
}
|
|
/* if extended permissions are not defined, only consider av_decision */
|
|
if (!xp_node || !xp_node->xp.len)
|
|
goto decision;
|
|
|
|
local_xpd.allowed = &allowed;
|
|
local_xpd.auditallow = &auditallow;
|
|
local_xpd.dontaudit = &dontaudit;
|
|
|
|
xpd = avc_xperms_decision_lookup(driver, xp_node);
|
|
if (unlikely(!xpd)) {
|
|
/*
|
|
* Compute the extended_perms_decision only if the driver
|
|
* is flagged
|
|
*/
|
|
if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
|
|
avd.allowed &= ~requested;
|
|
goto decision;
|
|
}
|
|
rcu_read_unlock();
|
|
security_compute_xperms_decision(state, ssid, tsid, tclass,
|
|
driver, &local_xpd);
|
|
rcu_read_lock();
|
|
avc_update_node(state->avc, AVC_CALLBACK_ADD_XPERMS, requested,
|
|
driver, xperm, ssid, tsid, tclass, avd.seqno,
|
|
&local_xpd, 0);
|
|
} else {
|
|
avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
|
|
}
|
|
xpd = &local_xpd;
|
|
|
|
if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
|
|
avd.allowed &= ~requested;
|
|
|
|
decision:
|
|
denied = requested & ~(avd.allowed);
|
|
if (unlikely(denied))
|
|
rc = avc_denied(state, ssid, tsid, tclass, requested,
|
|
driver, xperm, AVC_EXTENDED_PERMS, &avd);
|
|
|
|
rcu_read_unlock();
|
|
|
|
rc2 = avc_xperms_audit(state, ssid, tsid, tclass, requested,
|
|
&avd, xpd, xperm, rc, ad);
|
|
if (rc2)
|
|
return rc2;
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* avc_has_perm_noaudit - Check permissions but perform no auditing.
|
|
* @ssid: source security identifier
|
|
* @tsid: target security identifier
|
|
* @tclass: target security class
|
|
* @requested: requested permissions, interpreted based on @tclass
|
|
* @flags: AVC_STRICT or 0
|
|
* @avd: access vector decisions
|
|
*
|
|
* Check the AVC to determine whether the @requested permissions are granted
|
|
* for the SID pair (@ssid, @tsid), interpreting the permissions
|
|
* based on @tclass, and call the security server on a cache miss to obtain
|
|
* a new decision and add it to the cache. Return a copy of the decisions
|
|
* in @avd. Return %0 if all @requested permissions are granted,
|
|
* -%EACCES if any permissions are denied, or another -errno upon
|
|
* other errors. This function is typically called by avc_has_perm(),
|
|
* but may also be called directly to separate permission checking from
|
|
* auditing, e.g. in cases where a lock must be held for the check but
|
|
* should be released for the auditing.
|
|
*/
|
|
inline int avc_has_perm_noaudit(struct selinux_state *state,
|
|
u32 ssid, u32 tsid,
|
|
u16 tclass, u32 requested,
|
|
unsigned int flags,
|
|
struct av_decision *avd)
|
|
{
|
|
struct avc_node *node;
|
|
struct avc_xperms_node xp_node;
|
|
int rc = 0;
|
|
u32 denied;
|
|
|
|
BUG_ON(!requested);
|
|
|
|
rcu_read_lock();
|
|
|
|
node = avc_lookup(state->avc, ssid, tsid, tclass);
|
|
if (unlikely(!node))
|
|
node = avc_compute_av(state, ssid, tsid, tclass, avd, &xp_node);
|
|
else
|
|
memcpy(avd, &node->ae.avd, sizeof(*avd));
|
|
|
|
denied = requested & ~(avd->allowed);
|
|
if (unlikely(denied))
|
|
rc = avc_denied(state, ssid, tsid, tclass, requested, 0, 0,
|
|
flags, avd);
|
|
|
|
rcu_read_unlock();
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* avc_has_perm - Check permissions and perform any appropriate auditing.
|
|
* @ssid: source security identifier
|
|
* @tsid: target security identifier
|
|
* @tclass: target security class
|
|
* @requested: requested permissions, interpreted based on @tclass
|
|
* @auditdata: auxiliary audit data
|
|
*
|
|
* Check the AVC to determine whether the @requested permissions are granted
|
|
* for the SID pair (@ssid, @tsid), interpreting the permissions
|
|
* based on @tclass, and call the security server on a cache miss to obtain
|
|
* a new decision and add it to the cache. Audit the granting or denial of
|
|
* permissions in accordance with the policy. Return %0 if all @requested
|
|
* permissions are granted, -%EACCES if any permissions are denied, or
|
|
* another -errno upon other errors.
|
|
*/
|
|
int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
|
|
u32 requested, struct common_audit_data *auditdata)
|
|
{
|
|
struct av_decision avd;
|
|
int rc, rc2;
|
|
|
|
rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
|
|
&avd);
|
|
|
|
rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
|
|
auditdata, 0);
|
|
if (rc2)
|
|
return rc2;
|
|
return rc;
|
|
}
|
|
|
|
int avc_has_perm_flags(struct selinux_state *state,
|
|
u32 ssid, u32 tsid, u16 tclass, u32 requested,
|
|
struct common_audit_data *auditdata,
|
|
int flags)
|
|
{
|
|
struct av_decision avd;
|
|
int rc, rc2;
|
|
|
|
rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
|
|
&avd);
|
|
|
|
rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
|
|
auditdata, flags);
|
|
if (rc2)
|
|
return rc2;
|
|
return rc;
|
|
}
|
|
|
|
u32 avc_policy_seqno(struct selinux_state *state)
|
|
{
|
|
return state->avc->avc_cache.latest_notif;
|
|
}
|
|
|
|
void avc_disable(void)
|
|
{
|
|
/*
|
|
* If you are looking at this because you have realized that we are
|
|
* not destroying the avc_node_cachep it might be easy to fix, but
|
|
* I don't know the memory barrier semantics well enough to know. It's
|
|
* possible that some other task dereferenced security_ops when
|
|
* it still pointed to selinux operations. If that is the case it's
|
|
* possible that it is about to use the avc and is about to need the
|
|
* avc_node_cachep. I know I could wrap the security.c security_ops call
|
|
* in an rcu_lock, but seriously, it's not worth it. Instead I just flush
|
|
* the cache and get that memory back.
|
|
*/
|
|
if (avc_node_cachep) {
|
|
avc_flush(selinux_state.avc);
|
|
/* kmem_cache_destroy(avc_node_cachep); */
|
|
}
|
|
}
|