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-rw-r--r--security/selinux/avc.c1241
1 files changed, 1241 insertions, 0 deletions
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
new file mode 100644
index 000000000..884a014ce
--- /dev/null
+++ b/security/selinux/avc.c
@@ -0,0 +1,1241 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Implementation of the kernel access vector cache (AVC).
+ *
+ * Authors: Stephen Smalley, <sds@tycho.nsa.gov>
+ * 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>
+ */
+#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 CREATE_TRACE_POINTS
+#include <trace/events/avc.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;
+};
+
+#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
+DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
+#endif
+
+struct selinux_avc {
+ unsigned int avc_cache_threshold;
+ struct avc_cache avc_cache;
+};
+
+static struct selinux_avc selinux_avc;
+
+void selinux_avc_init(struct selinux_avc **avc)
+{
+ int i;
+
+ selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
+ for (i = 0; i < AVC_CACHE_SLOTS; i++) {
+ INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
+ spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
+ }
+ atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
+ atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
+ *avc = &selinux_avc;
+}
+
+unsigned int avc_get_cache_threshold(struct selinux_avc *avc)
+{
+ return avc->avc_cache_threshold;
+}
+
+void avc_set_cache_threshold(struct selinux_avc *avc,
+ unsigned int cache_threshold)
+{
+ avc->avc_cache_threshold = cache_threshold;
+}
+
+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_init - Initialize the AVC.
+ *
+ * Initialize the access vector cache.
+ */
+void __init avc_init(void)
+{
+ 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);
+}
+
+int avc_get_hash_stats(struct selinux_avc *avc, 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->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->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(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 | __GFP_NOWARN);
+ 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(&notif_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(&notif_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); */
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-23 22:18:16 +0000