| /* |
| * Implementation of the kernel access vector cache (AVC). |
| * |
| * Authors: Stephen Smalley, <sds@epoch.ncsc.mil> |
| * James Morris <jmorris@redhat.com> |
| * |
| * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com> |
| * Replaced the avc_lock spinlock by RCU. |
| * |
| * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2, |
| * as published by the Free Software Foundation. |
| */ |
| #include <linux/types.h> |
| #include <linux/stddef.h> |
| #include <linux/kernel.h> |
| #include <linux/slab.h> |
| #include <linux/fs.h> |
| #include <linux/dcache.h> |
| #include <linux/init.h> |
| #include <linux/skbuff.h> |
| #include <linux/percpu.h> |
| #include <linux/list.h> |
| #include <net/sock.h> |
| #include <linux/un.h> |
| #include <net/af_unix.h> |
| #include <linux/ip.h> |
| #include <linux/audit.h> |
| #include <linux/ipv6.h> |
| #include <net/ipv6.h> |
| #include "avc.h" |
| #include "avc_ss.h" |
| #include "classmap.h" |
| |
| #define AVC_CACHE_SLOTS 512 |
| #define AVC_DEF_CACHE_THRESHOLD 512 |
| #define AVC_CACHE_RECLAIM 16 |
| |
| #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS |
| #define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field) |
| #else |
| #define avc_cache_stats_incr(field) do {} while (0) |
| #endif |
| |
| struct avc_entry { |
| u32 ssid; |
| u32 tsid; |
| u16 tclass; |
| struct av_decision avd; |
| struct avc_xperms_node *xp_node; |
| }; |
| |
| struct avc_node { |
| struct avc_entry ae; |
| struct hlist_node list; /* anchored in avc_cache->slots[i] */ |
| struct rcu_head rhead; |
| }; |
| |
| struct avc_xperms_decision_node { |
| struct extended_perms_decision xpd; |
| struct list_head xpd_list; /* list of extended_perms_decision */ |
| }; |
| |
| struct avc_xperms_node { |
| struct extended_perms xp; |
| struct list_head xpd_head; /* list head of extended_perms_decision */ |
| }; |
| |
| struct avc_cache { |
| struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */ |
| spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */ |
| atomic_t lru_hint; /* LRU hint for reclaim scan */ |
| atomic_t active_nodes; |
| u32 latest_notif; /* latest revocation notification */ |
| }; |
| |
| struct avc_callback_node { |
| int (*callback) (u32 event); |
| u32 events; |
| struct avc_callback_node *next; |
| }; |
| |
| /* Exported via selinufs */ |
| unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD; |
| |
| #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS |
| DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 }; |
| #endif |
| |
| static struct avc_cache avc_cache; |
| static struct avc_callback_node *avc_callbacks; |
| static struct kmem_cache *avc_node_cachep; |
| static struct kmem_cache *avc_xperms_data_cachep; |
| static struct kmem_cache *avc_xperms_decision_cachep; |
| static struct kmem_cache *avc_xperms_cachep; |
| |
| static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass) |
| { |
| return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1); |
| } |
| |
| /** |
| * avc_dump_av - Display an access vector in human-readable form. |
| * @tclass: target security class |
| * @av: access vector |
| */ |
| static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av) |
| { |
| const char **perms; |
| int i, perm; |
| |
| if (av == 0) { |
| audit_log_format(ab, " null"); |
| return; |
| } |
| |
| BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)); |
| perms = secclass_map[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, " }"); |
| } |
| |
| /** |
| * avc_dump_query - Display a SID pair and a class in human-readable form. |
| * @ssid: source security identifier |
| * @tsid: target security identifier |
| * @tclass: target security class |
| */ |
| static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass) |
| { |
| int rc; |
| char *scontext; |
| u32 scontext_len; |
| |
| rc = security_sid_to_context(ssid, &scontext, &scontext_len); |
| if (rc) |
| audit_log_format(ab, "ssid=%d", ssid); |
| else { |
| audit_log_format(ab, "scontext=%s", scontext); |
| kfree(scontext); |
| } |
| |
| rc = security_sid_to_context(tsid, &scontext, &scontext_len); |
| if (rc) |
| audit_log_format(ab, " tsid=%d", tsid); |
| else { |
| audit_log_format(ab, " tcontext=%s", scontext); |
| kfree(scontext); |
| } |
| |
| BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)); |
| audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name); |
| } |
| |
| /** |
| * avc_init - Initialize the AVC. |
| * |
| * Initialize the access vector cache. |
| */ |
| void __init avc_init(void) |
| { |
| int i; |
| |
| for (i = 0; i < AVC_CACHE_SLOTS; i++) { |
| INIT_HLIST_HEAD(&avc_cache.slots[i]); |
| spin_lock_init(&avc_cache.slots_lock[i]); |
| } |
| atomic_set(&avc_cache.active_nodes, 0); |
| atomic_set(&avc_cache.lru_hint, 0); |
| |
| avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node), |
| 0, SLAB_PANIC, NULL); |
| avc_xperms_cachep = kmem_cache_create("avc_xperms_node", |
| sizeof(struct avc_xperms_node), |
| 0, SLAB_PANIC, NULL); |
| avc_xperms_decision_cachep = kmem_cache_create( |
| "avc_xperms_decision_node", |
| sizeof(struct avc_xperms_decision_node), |
| 0, SLAB_PANIC, NULL); |
| avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data", |
| sizeof(struct extended_perms_data), |
| 0, SLAB_PANIC, NULL); |
| |
| audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n"); |
| } |
| |
| int avc_get_hash_stats(char *page) |
| { |
| int i, chain_len, max_chain_len, slots_used; |
| struct avc_node *node; |
| struct hlist_head *head; |
| |
| rcu_read_lock(); |
| |
| slots_used = 0; |
| max_chain_len = 0; |
| for (i = 0; i < AVC_CACHE_SLOTS; i++) { |
| head = &avc_cache.slots[i]; |
| if (!hlist_empty(head)) { |
| slots_used++; |
| chain_len = 0; |
| hlist_for_each_entry_rcu(node, head, list) |
| chain_len++; |
| if (chain_len > max_chain_len) |
| max_chain_len = chain_len; |
| } |
| } |
| |
| rcu_read_unlock(); |
| |
| return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n" |
| "longest chain: %d\n", |
| atomic_read(&avc_cache.active_nodes), |
| slots_used, AVC_CACHE_SLOTS, max_chain_len); |
| } |
| |
| /* |
| * using a linked list for extended_perms_decision lookup because the list is |
| * always small. i.e. less than 5, typically 1 |
| */ |
| static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver, |
| struct avc_xperms_node *xp_node) |
| { |
| struct avc_xperms_decision_node *xpd_node; |
| |
| list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) { |
| if (xpd_node->xpd.driver == driver) |
| return &xpd_node->xpd; |
| } |
| return NULL; |
| } |
| |
| static inline unsigned int |
| avc_xperms_has_perm(struct extended_perms_decision *xpd, |
| u8 perm, u8 which) |
| { |
| unsigned int rc = 0; |
| |
| if ((which == XPERMS_ALLOWED) && |
| (xpd->used & XPERMS_ALLOWED)) |
| rc = security_xperm_test(xpd->allowed->p, perm); |
| else if ((which == XPERMS_AUDITALLOW) && |
| (xpd->used & XPERMS_AUDITALLOW)) |
| rc = security_xperm_test(xpd->auditallow->p, perm); |
| else if ((which == XPERMS_DONTAUDIT) && |
| (xpd->used & XPERMS_DONTAUDIT)) |
| rc = security_xperm_test(xpd->dontaudit->p, perm); |
| return rc; |
| } |
| |
| static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node, |
| u8 driver, u8 perm) |
| { |
| struct extended_perms_decision *xpd; |
| security_xperm_set(xp_node->xp.drivers.p, driver); |
| xpd = avc_xperms_decision_lookup(driver, xp_node); |
| if (xpd && xpd->allowed) |
| security_xperm_set(xpd->allowed->p, perm); |
| } |
| |
| static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node) |
| { |
| struct extended_perms_decision *xpd; |
| |
| xpd = &xpd_node->xpd; |
| if (xpd->allowed) |
| kmem_cache_free(avc_xperms_data_cachep, xpd->allowed); |
| if (xpd->auditallow) |
| kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow); |
| if (xpd->dontaudit) |
| kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit); |
| kmem_cache_free(avc_xperms_decision_cachep, xpd_node); |
| } |
| |
| static void avc_xperms_free(struct avc_xperms_node *xp_node) |
| { |
| struct avc_xperms_decision_node *xpd_node, *tmp; |
| |
| if (!xp_node) |
| return; |
| |
| list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) { |
| list_del(&xpd_node->xpd_list); |
| avc_xperms_decision_free(xpd_node); |
| } |
| kmem_cache_free(avc_xperms_cachep, xp_node); |
| } |
| |
| static void avc_copy_xperms_decision(struct extended_perms_decision *dest, |
| struct extended_perms_decision *src) |
| { |
| dest->driver = src->driver; |
| dest->used = src->used; |
| if (dest->used & XPERMS_ALLOWED) |
| memcpy(dest->allowed->p, src->allowed->p, |
| sizeof(src->allowed->p)); |
| if (dest->used & XPERMS_AUDITALLOW) |
| memcpy(dest->auditallow->p, src->auditallow->p, |
| sizeof(src->auditallow->p)); |
| if (dest->used & XPERMS_DONTAUDIT) |
| memcpy(dest->dontaudit->p, src->dontaudit->p, |
| sizeof(src->dontaudit->p)); |
| } |
| |
| /* |
| * similar to avc_copy_xperms_decision, but only copy decision |
| * information relevant to this perm |
| */ |
| static inline void avc_quick_copy_xperms_decision(u8 perm, |
| struct extended_perms_decision *dest, |
| struct extended_perms_decision *src) |
| { |
| /* |
| * compute index of the u32 of the 256 bits (8 u32s) that contain this |
| * command permission |
| */ |
| u8 i = perm >> 5; |
| |
| dest->used = src->used; |
| if (dest->used & XPERMS_ALLOWED) |
| dest->allowed->p[i] = src->allowed->p[i]; |
| if (dest->used & XPERMS_AUDITALLOW) |
| dest->auditallow->p[i] = src->auditallow->p[i]; |
| if (dest->used & XPERMS_DONTAUDIT) |
| dest->dontaudit->p[i] = src->dontaudit->p[i]; |
| } |
| |
| static struct avc_xperms_decision_node |
| *avc_xperms_decision_alloc(u8 which) |
| { |
| struct avc_xperms_decision_node *xpd_node; |
| struct extended_perms_decision *xpd; |
| |
| xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep, |
| GFP_NOWAIT | __GFP_NOWARN); |
| if (!xpd_node) |
| return NULL; |
| |
| xpd = &xpd_node->xpd; |
| if (which & XPERMS_ALLOWED) { |
| xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep, |
| GFP_NOWAIT | __GFP_NOWARN); |
| if (!xpd->allowed) |
| goto error; |
| } |
| if (which & XPERMS_AUDITALLOW) { |
| xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep, |
| GFP_NOWAIT | __GFP_NOWARN); |
| if (!xpd->auditallow) |
| goto error; |
| } |
| if (which & XPERMS_DONTAUDIT) { |
| xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep, |
| GFP_NOWAIT | __GFP_NOWARN); |
| if (!xpd->dontaudit) |
| goto error; |
| } |
| return xpd_node; |
| error: |
| avc_xperms_decision_free(xpd_node); |
| return NULL; |
| } |
| |
| static int avc_add_xperms_decision(struct avc_node *node, |
| struct extended_perms_decision *src) |
| { |
| struct avc_xperms_decision_node *dest_xpd; |
| |
| node->ae.xp_node->xp.len++; |
| dest_xpd = avc_xperms_decision_alloc(src->used); |
| if (!dest_xpd) |
| return -ENOMEM; |
| avc_copy_xperms_decision(&dest_xpd->xpd, src); |
| list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head); |
| return 0; |
| } |
| |
| static struct avc_xperms_node *avc_xperms_alloc(void) |
| { |
| struct avc_xperms_node *xp_node; |
| |
| xp_node = kmem_cache_zalloc(avc_xperms_cachep, |
| GFP_NOWAIT | __GFP_NOWARN); |
| if (!xp_node) |
| return xp_node; |
| INIT_LIST_HEAD(&xp_node->xpd_head); |
| return xp_node; |
| } |
| |
| static int avc_xperms_populate(struct avc_node *node, |
| struct avc_xperms_node *src) |
| { |
| 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) |
| return -ENOMEM; |
| |
| memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p)); |
| dest->xp.len = src->xp.len; |
| |
| /* 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); |
| } |
| 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, |
| 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(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(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 avc_node *node) |
| { |
| hlist_del_rcu(&node->list); |
| call_rcu(&node->rhead, avc_node_free); |
| atomic_dec(&avc_cache.active_nodes); |
| } |
| |
| static void avc_node_kill(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_cache.active_nodes); |
| } |
| |
| static void avc_node_replace(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_cache.active_nodes); |
| } |
| |
| static inline int avc_reclaim_node(void) |
| { |
| 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_cache.lru_hint) & (AVC_CACHE_SLOTS - 1); |
| head = &avc_cache.slots[hvalue]; |
| lock = &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(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(void) |
| { |
| struct avc_node *node; |
| |
| node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT | __GFP_NOWARN); |
| if (!node) |
| goto out; |
| |
| INIT_HLIST_NODE(&node->list); |
| avc_cache_stats_incr(allocations); |
| |
| if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold) |
| avc_reclaim_node(); |
| |
| 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(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_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(u32 ssid, u32 tsid, u16 tclass) |
| { |
| struct avc_node *node; |
| |
| avc_cache_stats_incr(lookups); |
| node = avc_search_node(ssid, tsid, tclass); |
| |
| if (node) |
| return node; |
| |
| avc_cache_stats_incr(misses); |
| return NULL; |
| } |
| |
| static int avc_latest_notif_update(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_cache.latest_notif) { |
| printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n", |
| seqno, avc_cache.latest_notif); |
| ret = -EAGAIN; |
| } |
| } else { |
| if (seqno > avc_cache.latest_notif) |
| 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(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(avd->seqno, 1)) |
| goto out; |
| |
| node = avc_alloc_node(); |
| 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_cache.slots[hvalue]; |
| lock = &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(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->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(u32 ssid, u32 tsid, u16 tclass, |
| u32 requested, u32 audited, u32 denied, int result, |
| struct common_audit_data *a, |
| unsigned 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; |
| |
| 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(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(); |
| if (!node) { |
| rc = -ENOMEM; |
| goto out; |
| } |
| |
| /* Lock the target slot */ |
| hvalue = avc_hash(ssid, tsid, tclass); |
| |
| head = &avc_cache.slots[hvalue]; |
| lock = &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(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(node, orig); |
| out_unlock: |
| spin_unlock_irqrestore(lock, flag); |
| out: |
| return rc; |
| } |
| |
| /** |
| * avc_flush - Flush the cache |
| */ |
| static void avc_flush(void) |
| { |
| 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_cache.slots[i]; |
| lock = &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(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(u32 seqno) |
| { |
| struct avc_callback_node *c; |
| int rc = 0, tmprc; |
| |
| avc_flush(); |
| |
| 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(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(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(ssid, tsid, tclass, avd, &xp_node->xp); |
| rcu_read_lock(); |
| return avc_insert(ssid, tsid, tclass, avd, xp_node); |
| } |
| |
| static noinline int avc_denied(u32 ssid, u32 tsid, |
| u16 tclass, u32 requested, |
| u8 driver, u8 xperm, unsigned flags, |
| struct av_decision *avd) |
| { |
| if (flags & AVC_STRICT) |
| return -EACCES; |
| |
| if (selinux_enforcing && !(avd->flags & AVD_FLAGS_PERMISSIVE)) |
| return -EACCES; |
| |
| avc_update_node(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(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(ssid, tsid, tclass); |
| if (unlikely(!node)) { |
| node = avc_compute_av(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(ssid, tsid, tclass, driver, |
| &local_xpd); |
| rcu_read_lock(); |
| avc_update_node(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(ssid, tsid, tclass, requested, driver, xperm, |
| AVC_EXTENDED_PERMS, &avd); |
| |
| rcu_read_unlock(); |
| |
| rc2 = avc_xperms_audit(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(u32 ssid, u32 tsid, |
| u16 tclass, u32 requested, |
| unsigned 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(ssid, tsid, tclass); |
| if (unlikely(!node)) |
| node = avc_compute_av(ssid, tsid, tclass, avd, &xp_node); |
| else |
| memcpy(avd, &node->ae.avd, sizeof(*avd)); |
| |
| denied = requested & ~(avd->allowed); |
| if (unlikely(denied)) |
| rc = avc_denied(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(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(ssid, tsid, tclass, requested, 0, &avd); |
| |
| rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata, 0); |
| if (rc2) |
| return rc2; |
| return rc; |
| } |
| |
| int avc_has_perm_flags(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(ssid, tsid, tclass, requested, 0, &avd); |
| |
| rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, |
| auditdata, flags); |
| if (rc2) |
| return rc2; |
| return rc; |
| } |
| |
| u32 avc_policy_seqno(void) |
| { |
| return 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(); |
| /* kmem_cache_destroy(avc_node_cachep); */ |
| } |
| } |