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1240 lines
32 KiB
1240 lines
32 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Implementation of the kernel access vector cache (AVC). |
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* |
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* Authors: Stephen Smalley, <[email protected]> |
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* James Morris <[email protected]> |
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* |
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* Update: KaiGai, Kohei <[email protected]> |
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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 <[email protected]> |
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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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|
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#define CREATE_TRACE_POINTS |
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#include <trace/events/avc.h> |
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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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static struct selinux_avc selinux_avc; |
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|
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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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|
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static struct avc_callback_node *avc_callbacks __ro_after_init; |
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static struct kmem_cache *avc_node_cachep __ro_after_init; |
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static struct kmem_cache *avc_xperms_data_cachep __ro_after_init; |
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static struct kmem_cache *avc_xperms_decision_cachep __ro_after_init; |
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static struct kmem_cache *avc_xperms_cachep __ro_after_init; |
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|
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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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/** |
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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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|
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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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|
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rcu_read_unlock(); |
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|
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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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|
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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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|
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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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|
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if (!xp_node) |
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return; |
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|
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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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/* |
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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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|
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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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|
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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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|
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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); |
|
if (!xpd->dontaudit) |
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goto error; |
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} |
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return xpd_node; |
|
error: |
|
avc_xperms_decision_free(xpd_node); |
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return NULL; |
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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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static struct avc_xperms_node *avc_xperms_alloc(void) |
|
{ |
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struct avc_xperms_node *xp_node; |
|
|
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xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT); |
|
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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static int avc_xperms_populate(struct avc_node *node, |
|
struct avc_xperms_node *src) |
|
{ |
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struct avc_xperms_node *dest; |
|
struct avc_xperms_decision_node *dest_xpd; |
|
struct avc_xperms_decision_node *src_xpd; |
|
|
|
if (src->xp.len == 0) |
|
return 0; |
|
dest = avc_xperms_alloc(); |
|
if (!dest) |
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return -ENOMEM; |
|
|
|
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 */ |
|
list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) { |
|
dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used); |
|
if (!dest_xpd) |
|
goto error; |
|
avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd); |
|
list_add(&dest_xpd->xpd_list, &dest->xpd_head); |
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} |
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node->ae.xp_node = dest; |
|
return 0; |
|
error: |
|
avc_xperms_free(dest); |
|
return -ENOMEM; |
|
|
|
} |
|
|
|
static inline u32 avc_xperms_audit_required(u32 requested, |
|
struct av_decision *avd, |
|
struct extended_perms_decision *xpd, |
|
u8 perm, |
|
int result, |
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u32 *deniedp) |
|
{ |
|
u32 denied, audited; |
|
|
|
denied = requested & ~avd->allowed; |
|
if (unlikely(denied)) { |
|
audited = denied & avd->auditdeny; |
|
if (audited && xpd) { |
|
if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT)) |
|
audited &= ~requested; |
|
} |
|
} 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); |
|
} |
|
|
|
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; |
|
spinlock_t *lock; |
|
struct hlist_head *head; |
|
|
|
if (avc_latest_notif_update(avc, avd->seqno, 1)) |
|
return NULL; |
|
|
|
node = avc_alloc_node(avc); |
|
if (!node) |
|
return NULL; |
|
|
|
avc_node_populate(node, ssid, tsid, tclass, avd); |
|
if (avc_xperms_populate(node, xp_node)) { |
|
avc_node_kill(avc, node); |
|
return NULL; |
|
} |
|
|
|
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 (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); |
|
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; |
|
struct selinux_audit_data *sad = ad->selinux_audit_data; |
|
u32 av = sad->audited; |
|
const char **perms; |
|
int i, perm; |
|
|
|
audit_log_format(ab, "avc: %s ", sad->denied ? "denied" : "granted"); |
|
|
|
if (av == 0) { |
|
audit_log_format(ab, " null"); |
|
return; |
|
} |
|
|
|
perms = secclass_map[sad->tclass-1].perms; |
|
|
|
audit_log_format(ab, " {"); |
|
i = 0; |
|
perm = 1; |
|
while (i < (sizeof(av) * 8)) { |
|
if ((perm & av) && perms[i]) { |
|
audit_log_format(ab, " %s", perms[i]); |
|
av &= ~perm; |
|
} |
|
i++; |
|
perm <<= 1; |
|
} |
|
|
|
if (av) |
|
audit_log_format(ab, " 0x%x", av); |
|
|
|
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; |
|
struct selinux_audit_data *sad = ad->selinux_audit_data; |
|
char *scontext = NULL; |
|
char *tcontext = NULL; |
|
const char *tclass = NULL; |
|
u32 scontext_len; |
|
u32 tcontext_len; |
|
int rc; |
|
|
|
rc = security_sid_to_context(sad->state, sad->ssid, &scontext, |
|
&scontext_len); |
|
if (rc) |
|
audit_log_format(ab, " ssid=%d", sad->ssid); |
|
else |
|
audit_log_format(ab, " scontext=%s", scontext); |
|
|
|
rc = security_sid_to_context(sad->state, sad->tsid, &tcontext, |
|
&tcontext_len); |
|
if (rc) |
|
audit_log_format(ab, " tsid=%d", sad->tsid); |
|
else |
|
audit_log_format(ab, " tcontext=%s", tcontext); |
|
|
|
tclass = secclass_map[sad->tclass-1].name; |
|
audit_log_format(ab, " tclass=%s", tclass); |
|
|
|
if (sad->denied) |
|
audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1); |
|
|
|
trace_selinux_audited(sad, scontext, tcontext, tclass); |
|
kfree(tcontext); |
|
kfree(scontext); |
|
|
|
/* in case of invalid context report also the actual context string */ |
|
rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext, |
|
&scontext_len); |
|
if (!rc && scontext) { |
|
if (scontext_len && scontext[scontext_len - 1] == '\0') |
|
scontext_len--; |
|
audit_log_format(ab, " srawcon="); |
|
audit_log_n_untrustedstring(ab, scontext, scontext_len); |
|
kfree(scontext); |
|
} |
|
|
|
rc = security_sid_to_context_inval(sad->state, sad->tsid, &scontext, |
|
&scontext_len); |
|
if (!rc && scontext) { |
|
if (scontext_len && scontext[scontext_len - 1] == '\0') |
|
scontext_len--; |
|
audit_log_format(ab, " trawcon="); |
|
audit_log_n_untrustedstring(ab, scontext, scontext_len); |
|
kfree(scontext); |
|
} |
|
} |
|
|
|
/* 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) |
|
{ |
|
struct common_audit_data stack_data; |
|
struct selinux_audit_data sad; |
|
|
|
if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map))) |
|
return -EINVAL; |
|
|
|
if (!a) { |
|
a = &stack_data; |
|
a->type = LSM_AUDIT_DATA_NONE; |
|
} |
|
|
|
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 |
|
* @flags: the AVC_* flags, e.g. AVC_NONBLOCKING, AVC_EXTENDED_PERMS, or 0. |
|
* |
|
* 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; |
|
|
|
/* |
|
* If we are in a non-blocking code path, e.g. VFS RCU walk, |
|
* then we must not add permissions to a cache entry |
|
* because we will not audit the denial. Otherwise, |
|
* during the subsequent blocking retry (e.g. VFS ref walk), we |
|
* will find the permissions already granted in the cache entry |
|
* and won't audit anything at all, leading to silent denials in |
|
* permissive mode that only appear when in enforcing mode. |
|
* |
|
* See the corresponding handling of MAY_NOT_BLOCK in avc_audit() |
|
* and selinux_inode_permission(). |
|
*/ |
|
if (flags & AVC_NONBLOCKING) |
|
return 0; |
|
|
|
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) { |
|
avc_node_kill(avc, 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; |
|
if (WARN_ON(!requested)) |
|
return -EACCES; |
|
|
|
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, AVC_NONBLOCKING, 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; |
|
|
|
if (WARN_ON(!requested)) |
|
return -EACCES; |
|
|
|
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, |
|
(flags & MAY_NOT_BLOCK) ? AVC_NONBLOCKING : 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); */ |
|
} |
|
}
|
|
|