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-rw-r--r--kernel/audit_tree.c1089
1 files changed, 1089 insertions, 0 deletions
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
new file mode 100644
index 000000000..39241207e
--- /dev/null
+++ b/kernel/audit_tree.c
@@ -0,0 +1,1089 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "audit.h"
+#include <linux/fsnotify_backend.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
+#include <linux/kthread.h>
+#include <linux/refcount.h>
+#include <linux/slab.h>
+
+struct audit_tree;
+struct audit_chunk;
+
+struct audit_tree {
+ refcount_t count;
+ int goner;
+ struct audit_chunk *root;
+ struct list_head chunks;
+ struct list_head rules;
+ struct list_head list;
+ struct list_head same_root;
+ struct rcu_head head;
+ char pathname[];
+};
+
+struct audit_chunk {
+ struct list_head hash;
+ unsigned long key;
+ struct fsnotify_mark *mark;
+ struct list_head trees; /* with root here */
+ int count;
+ atomic_long_t refs;
+ struct rcu_head head;
+ struct node {
+ struct list_head list;
+ struct audit_tree *owner;
+ unsigned index; /* index; upper bit indicates 'will prune' */
+ } owners[];
+};
+
+struct audit_tree_mark {
+ struct fsnotify_mark mark;
+ struct audit_chunk *chunk;
+};
+
+static LIST_HEAD(tree_list);
+static LIST_HEAD(prune_list);
+static struct task_struct *prune_thread;
+
+/*
+ * One struct chunk is attached to each inode of interest through
+ * audit_tree_mark (fsnotify mark). We replace struct chunk on tagging /
+ * untagging, the mark is stable as long as there is chunk attached. The
+ * association between mark and chunk is protected by hash_lock and
+ * audit_tree_group->mark_mutex. Thus as long as we hold
+ * audit_tree_group->mark_mutex and check that the mark is alive by
+ * FSNOTIFY_MARK_FLAG_ATTACHED flag check, we are sure the mark points to
+ * the current chunk.
+ *
+ * Rules have pointer to struct audit_tree.
+ * Rules have struct list_head rlist forming a list of rules over
+ * the same tree.
+ * References to struct chunk are collected at audit_inode{,_child}()
+ * time and used in AUDIT_TREE rule matching.
+ * These references are dropped at the same time we are calling
+ * audit_free_names(), etc.
+ *
+ * Cyclic lists galore:
+ * tree.chunks anchors chunk.owners[].list hash_lock
+ * tree.rules anchors rule.rlist audit_filter_mutex
+ * chunk.trees anchors tree.same_root hash_lock
+ * chunk.hash is a hash with middle bits of watch.inode as
+ * a hash function. RCU, hash_lock
+ *
+ * tree is refcounted; one reference for "some rules on rules_list refer to
+ * it", one for each chunk with pointer to it.
+ *
+ * chunk is refcounted by embedded .refs. Mark associated with the chunk holds
+ * one chunk reference. This reference is dropped either when a mark is going
+ * to be freed (corresponding inode goes away) or when chunk attached to the
+ * mark gets replaced. This reference must be dropped using
+ * audit_mark_put_chunk() to make sure the reference is dropped only after RCU
+ * grace period as it protects RCU readers of the hash table.
+ *
+ * node.index allows to get from node.list to containing chunk.
+ * MSB of that sucker is stolen to mark taggings that we might have to
+ * revert - several operations have very unpleasant cleanup logics and
+ * that makes a difference. Some.
+ */
+
+static struct fsnotify_group *audit_tree_group;
+static struct kmem_cache *audit_tree_mark_cachep __read_mostly;
+
+static struct audit_tree *alloc_tree(const char *s)
+{
+ struct audit_tree *tree;
+
+ tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
+ if (tree) {
+ refcount_set(&tree->count, 1);
+ tree->goner = 0;
+ INIT_LIST_HEAD(&tree->chunks);
+ INIT_LIST_HEAD(&tree->rules);
+ INIT_LIST_HEAD(&tree->list);
+ INIT_LIST_HEAD(&tree->same_root);
+ tree->root = NULL;
+ strcpy(tree->pathname, s);
+ }
+ return tree;
+}
+
+static inline void get_tree(struct audit_tree *tree)
+{
+ refcount_inc(&tree->count);
+}
+
+static inline void put_tree(struct audit_tree *tree)
+{
+ if (refcount_dec_and_test(&tree->count))
+ kfree_rcu(tree, head);
+}
+
+/* to avoid bringing the entire thing in audit.h */
+const char *audit_tree_path(struct audit_tree *tree)
+{
+ return tree->pathname;
+}
+
+static void free_chunk(struct audit_chunk *chunk)
+{
+ int i;
+
+ for (i = 0; i < chunk->count; i++) {
+ if (chunk->owners[i].owner)
+ put_tree(chunk->owners[i].owner);
+ }
+ kfree(chunk);
+}
+
+void audit_put_chunk(struct audit_chunk *chunk)
+{
+ if (atomic_long_dec_and_test(&chunk->refs))
+ free_chunk(chunk);
+}
+
+static void __put_chunk(struct rcu_head *rcu)
+{
+ struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
+ audit_put_chunk(chunk);
+}
+
+/*
+ * Drop reference to the chunk that was held by the mark. This is the reference
+ * that gets dropped after we've removed the chunk from the hash table and we
+ * use it to make sure chunk cannot be freed before RCU grace period expires.
+ */
+static void audit_mark_put_chunk(struct audit_chunk *chunk)
+{
+ call_rcu(&chunk->head, __put_chunk);
+}
+
+static inline struct audit_tree_mark *audit_mark(struct fsnotify_mark *mark)
+{
+ return container_of(mark, struct audit_tree_mark, mark);
+}
+
+static struct audit_chunk *mark_chunk(struct fsnotify_mark *mark)
+{
+ return audit_mark(mark)->chunk;
+}
+
+static void audit_tree_destroy_watch(struct fsnotify_mark *mark)
+{
+ kmem_cache_free(audit_tree_mark_cachep, audit_mark(mark));
+}
+
+static struct fsnotify_mark *alloc_mark(void)
+{
+ struct audit_tree_mark *amark;
+
+ amark = kmem_cache_zalloc(audit_tree_mark_cachep, GFP_KERNEL);
+ if (!amark)
+ return NULL;
+ fsnotify_init_mark(&amark->mark, audit_tree_group);
+ amark->mark.mask = FS_IN_IGNORED;
+ return &amark->mark;
+}
+
+static struct audit_chunk *alloc_chunk(int count)
+{
+ struct audit_chunk *chunk;
+ int i;
+
+ chunk = kzalloc(struct_size(chunk, owners, count), GFP_KERNEL);
+ if (!chunk)
+ return NULL;
+
+ INIT_LIST_HEAD(&chunk->hash);
+ INIT_LIST_HEAD(&chunk->trees);
+ chunk->count = count;
+ atomic_long_set(&chunk->refs, 1);
+ for (i = 0; i < count; i++) {
+ INIT_LIST_HEAD(&chunk->owners[i].list);
+ chunk->owners[i].index = i;
+ }
+ return chunk;
+}
+
+enum {HASH_SIZE = 128};
+static struct list_head chunk_hash_heads[HASH_SIZE];
+static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
+
+/* Function to return search key in our hash from inode. */
+static unsigned long inode_to_key(const struct inode *inode)
+{
+ /* Use address pointed to by connector->obj as the key */
+ return (unsigned long)&inode->i_fsnotify_marks;
+}
+
+static inline struct list_head *chunk_hash(unsigned long key)
+{
+ unsigned long n = key / L1_CACHE_BYTES;
+ return chunk_hash_heads + n % HASH_SIZE;
+}
+
+/* hash_lock & mark->group->mark_mutex is held by caller */
+static void insert_hash(struct audit_chunk *chunk)
+{
+ struct list_head *list;
+
+ /*
+ * Make sure chunk is fully initialized before making it visible in the
+ * hash. Pairs with a data dependency barrier in READ_ONCE() in
+ * audit_tree_lookup().
+ */
+ smp_wmb();
+ WARN_ON_ONCE(!chunk->key);
+ list = chunk_hash(chunk->key);
+ list_add_rcu(&chunk->hash, list);
+}
+
+/* called under rcu_read_lock */
+struct audit_chunk *audit_tree_lookup(const struct inode *inode)
+{
+ unsigned long key = inode_to_key(inode);
+ struct list_head *list = chunk_hash(key);
+ struct audit_chunk *p;
+
+ list_for_each_entry_rcu(p, list, hash) {
+ /*
+ * We use a data dependency barrier in READ_ONCE() to make sure
+ * the chunk we see is fully initialized.
+ */
+ if (READ_ONCE(p->key) == key) {
+ atomic_long_inc(&p->refs);
+ return p;
+ }
+ }
+ return NULL;
+}
+
+bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
+{
+ int n;
+ for (n = 0; n < chunk->count; n++)
+ if (chunk->owners[n].owner == tree)
+ return true;
+ return false;
+}
+
+/* tagging and untagging inodes with trees */
+
+static struct audit_chunk *find_chunk(struct node *p)
+{
+ int index = p->index & ~(1U<<31);
+ p -= index;
+ return container_of(p, struct audit_chunk, owners[0]);
+}
+
+static void replace_mark_chunk(struct fsnotify_mark *mark,
+ struct audit_chunk *chunk)
+{
+ struct audit_chunk *old;
+
+ assert_spin_locked(&hash_lock);
+ old = mark_chunk(mark);
+ audit_mark(mark)->chunk = chunk;
+ if (chunk)
+ chunk->mark = mark;
+ if (old)
+ old->mark = NULL;
+}
+
+static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old)
+{
+ struct audit_tree *owner;
+ int i, j;
+
+ new->key = old->key;
+ list_splice_init(&old->trees, &new->trees);
+ list_for_each_entry(owner, &new->trees, same_root)
+ owner->root = new;
+ for (i = j = 0; j < old->count; i++, j++) {
+ if (!old->owners[j].owner) {
+ i--;
+ continue;
+ }
+ owner = old->owners[j].owner;
+ new->owners[i].owner = owner;
+ new->owners[i].index = old->owners[j].index - j + i;
+ if (!owner) /* result of earlier fallback */
+ continue;
+ get_tree(owner);
+ list_replace_init(&old->owners[j].list, &new->owners[i].list);
+ }
+ replace_mark_chunk(old->mark, new);
+ /*
+ * Make sure chunk is fully initialized before making it visible in the
+ * hash. Pairs with a data dependency barrier in READ_ONCE() in
+ * audit_tree_lookup().
+ */
+ smp_wmb();
+ list_replace_rcu(&old->hash, &new->hash);
+}
+
+static void remove_chunk_node(struct audit_chunk *chunk, struct node *p)
+{
+ struct audit_tree *owner = p->owner;
+
+ if (owner->root == chunk) {
+ list_del_init(&owner->same_root);
+ owner->root = NULL;
+ }
+ list_del_init(&p->list);
+ p->owner = NULL;
+ put_tree(owner);
+}
+
+static int chunk_count_trees(struct audit_chunk *chunk)
+{
+ int i;
+ int ret = 0;
+
+ for (i = 0; i < chunk->count; i++)
+ if (chunk->owners[i].owner)
+ ret++;
+ return ret;
+}
+
+static void untag_chunk(struct audit_chunk *chunk, struct fsnotify_mark *mark)
+{
+ struct audit_chunk *new;
+ int size;
+
+ mutex_lock(&audit_tree_group->mark_mutex);
+ /*
+ * mark_mutex stabilizes chunk attached to the mark so we can check
+ * whether it didn't change while we've dropped hash_lock.
+ */
+ if (!(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) ||
+ mark_chunk(mark) != chunk)
+ goto out_mutex;
+
+ size = chunk_count_trees(chunk);
+ if (!size) {
+ spin_lock(&hash_lock);
+ list_del_init(&chunk->trees);
+ list_del_rcu(&chunk->hash);
+ replace_mark_chunk(mark, NULL);
+ spin_unlock(&hash_lock);
+ fsnotify_detach_mark(mark);
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ audit_mark_put_chunk(chunk);
+ fsnotify_free_mark(mark);
+ return;
+ }
+
+ new = alloc_chunk(size);
+ if (!new)
+ goto out_mutex;
+
+ spin_lock(&hash_lock);
+ /*
+ * This has to go last when updating chunk as once replace_chunk() is
+ * called, new RCU readers can see the new chunk.
+ */
+ replace_chunk(new, chunk);
+ spin_unlock(&hash_lock);
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ audit_mark_put_chunk(chunk);
+ return;
+
+out_mutex:
+ mutex_unlock(&audit_tree_group->mark_mutex);
+}
+
+/* Call with group->mark_mutex held, releases it */
+static int create_chunk(struct inode *inode, struct audit_tree *tree)
+{
+ struct fsnotify_mark *mark;
+ struct audit_chunk *chunk = alloc_chunk(1);
+
+ if (!chunk) {
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ return -ENOMEM;
+ }
+
+ mark = alloc_mark();
+ if (!mark) {
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ kfree(chunk);
+ return -ENOMEM;
+ }
+
+ if (fsnotify_add_inode_mark_locked(mark, inode, 0)) {
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ fsnotify_put_mark(mark);
+ kfree(chunk);
+ return -ENOSPC;
+ }
+
+ spin_lock(&hash_lock);
+ if (tree->goner) {
+ spin_unlock(&hash_lock);
+ fsnotify_detach_mark(mark);
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ fsnotify_free_mark(mark);
+ fsnotify_put_mark(mark);
+ kfree(chunk);
+ return 0;
+ }
+ replace_mark_chunk(mark, chunk);
+ chunk->owners[0].index = (1U << 31);
+ chunk->owners[0].owner = tree;
+ get_tree(tree);
+ list_add(&chunk->owners[0].list, &tree->chunks);
+ if (!tree->root) {
+ tree->root = chunk;
+ list_add(&tree->same_root, &chunk->trees);
+ }
+ chunk->key = inode_to_key(inode);
+ /*
+ * Inserting into the hash table has to go last as once we do that RCU
+ * readers can see the chunk.
+ */
+ insert_hash(chunk);
+ spin_unlock(&hash_lock);
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ /*
+ * Drop our initial reference. When mark we point to is getting freed,
+ * we get notification through ->freeing_mark callback and cleanup
+ * chunk pointing to this mark.
+ */
+ fsnotify_put_mark(mark);
+ return 0;
+}
+
+/* the first tagged inode becomes root of tree */
+static int tag_chunk(struct inode *inode, struct audit_tree *tree)
+{
+ struct fsnotify_mark *mark;
+ struct audit_chunk *chunk, *old;
+ struct node *p;
+ int n;
+
+ mutex_lock(&audit_tree_group->mark_mutex);
+ mark = fsnotify_find_mark(&inode->i_fsnotify_marks, audit_tree_group);
+ if (!mark)
+ return create_chunk(inode, tree);
+
+ /*
+ * Found mark is guaranteed to be attached and mark_mutex protects mark
+ * from getting detached and thus it makes sure there is chunk attached
+ * to the mark.
+ */
+ /* are we already there? */
+ spin_lock(&hash_lock);
+ old = mark_chunk(mark);
+ for (n = 0; n < old->count; n++) {
+ if (old->owners[n].owner == tree) {
+ spin_unlock(&hash_lock);
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ fsnotify_put_mark(mark);
+ return 0;
+ }
+ }
+ spin_unlock(&hash_lock);
+
+ chunk = alloc_chunk(old->count + 1);
+ if (!chunk) {
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ fsnotify_put_mark(mark);
+ return -ENOMEM;
+ }
+
+ spin_lock(&hash_lock);
+ if (tree->goner) {
+ spin_unlock(&hash_lock);
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ fsnotify_put_mark(mark);
+ kfree(chunk);
+ return 0;
+ }
+ p = &chunk->owners[chunk->count - 1];
+ p->index = (chunk->count - 1) | (1U<<31);
+ p->owner = tree;
+ get_tree(tree);
+ list_add(&p->list, &tree->chunks);
+ if (!tree->root) {
+ tree->root = chunk;
+ list_add(&tree->same_root, &chunk->trees);
+ }
+ /*
+ * This has to go last when updating chunk as once replace_chunk() is
+ * called, new RCU readers can see the new chunk.
+ */
+ replace_chunk(chunk, old);
+ spin_unlock(&hash_lock);
+ mutex_unlock(&audit_tree_group->mark_mutex);
+ fsnotify_put_mark(mark); /* pair to fsnotify_find_mark */
+ audit_mark_put_chunk(old);
+
+ return 0;
+}
+
+static void audit_tree_log_remove_rule(struct audit_context *context,
+ struct audit_krule *rule)
+{
+ struct audit_buffer *ab;
+
+ if (!audit_enabled)
+ return;
+ ab = audit_log_start(context, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
+ if (unlikely(!ab))
+ return;
+ audit_log_format(ab, "op=remove_rule dir=");
+ audit_log_untrustedstring(ab, rule->tree->pathname);
+ audit_log_key(ab, rule->filterkey);
+ audit_log_format(ab, " list=%d res=1", rule->listnr);
+ audit_log_end(ab);
+}
+
+static void kill_rules(struct audit_context *context, struct audit_tree *tree)
+{
+ struct audit_krule *rule, *next;
+ struct audit_entry *entry;
+
+ list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
+ entry = container_of(rule, struct audit_entry, rule);
+
+ list_del_init(&rule->rlist);
+ if (rule->tree) {
+ /* not a half-baked one */
+ audit_tree_log_remove_rule(context, rule);
+ if (entry->rule.exe)
+ audit_remove_mark(entry->rule.exe);
+ rule->tree = NULL;
+ list_del_rcu(&entry->list);
+ list_del(&entry->rule.list);
+ call_rcu(&entry->rcu, audit_free_rule_rcu);
+ }
+ }
+}
+
+/*
+ * Remove tree from chunks. If 'tagged' is set, remove tree only from tagged
+ * chunks. The function expects tagged chunks are all at the beginning of the
+ * chunks list.
+ */
+static void prune_tree_chunks(struct audit_tree *victim, bool tagged)
+{
+ spin_lock(&hash_lock);
+ while (!list_empty(&victim->chunks)) {
+ struct node *p;
+ struct audit_chunk *chunk;
+ struct fsnotify_mark *mark;
+
+ p = list_first_entry(&victim->chunks, struct node, list);
+ /* have we run out of marked? */
+ if (tagged && !(p->index & (1U<<31)))
+ break;
+ chunk = find_chunk(p);
+ mark = chunk->mark;
+ remove_chunk_node(chunk, p);
+ /* Racing with audit_tree_freeing_mark()? */
+ if (!mark)
+ continue;
+ fsnotify_get_mark(mark);
+ spin_unlock(&hash_lock);
+
+ untag_chunk(chunk, mark);
+ fsnotify_put_mark(mark);
+
+ spin_lock(&hash_lock);
+ }
+ spin_unlock(&hash_lock);
+}
+
+/*
+ * finish killing struct audit_tree
+ */
+static void prune_one(struct audit_tree *victim)
+{
+ prune_tree_chunks(victim, false);
+ put_tree(victim);
+}
+
+/* trim the uncommitted chunks from tree */
+
+static void trim_marked(struct audit_tree *tree)
+{
+ struct list_head *p, *q;
+ spin_lock(&hash_lock);
+ if (tree->goner) {
+ spin_unlock(&hash_lock);
+ return;
+ }
+ /* reorder */
+ for (p = tree->chunks.next; p != &tree->chunks; p = q) {
+ struct node *node = list_entry(p, struct node, list);
+ q = p->next;
+ if (node->index & (1U<<31)) {
+ list_del_init(p);
+ list_add(p, &tree->chunks);
+ }
+ }
+ spin_unlock(&hash_lock);
+
+ prune_tree_chunks(tree, true);
+
+ spin_lock(&hash_lock);
+ if (!tree->root && !tree->goner) {
+ tree->goner = 1;
+ spin_unlock(&hash_lock);
+ mutex_lock(&audit_filter_mutex);
+ kill_rules(audit_context(), tree);
+ list_del_init(&tree->list);
+ mutex_unlock(&audit_filter_mutex);
+ prune_one(tree);
+ } else {
+ spin_unlock(&hash_lock);
+ }
+}
+
+static void audit_schedule_prune(void);
+
+/* called with audit_filter_mutex */
+int audit_remove_tree_rule(struct audit_krule *rule)
+{
+ struct audit_tree *tree;
+ tree = rule->tree;
+ if (tree) {
+ spin_lock(&hash_lock);
+ list_del_init(&rule->rlist);
+ if (list_empty(&tree->rules) && !tree->goner) {
+ tree->root = NULL;
+ list_del_init(&tree->same_root);
+ tree->goner = 1;
+ list_move(&tree->list, &prune_list);
+ rule->tree = NULL;
+ spin_unlock(&hash_lock);
+ audit_schedule_prune();
+ return 1;
+ }
+ rule->tree = NULL;
+ spin_unlock(&hash_lock);
+ return 1;
+ }
+ return 0;
+}
+
+static int compare_root(struct vfsmount *mnt, void *arg)
+{
+ return inode_to_key(d_backing_inode(mnt->mnt_root)) ==
+ (unsigned long)arg;
+}
+
+void audit_trim_trees(void)
+{
+ struct list_head cursor;
+
+ mutex_lock(&audit_filter_mutex);
+ list_add(&cursor, &tree_list);
+ while (cursor.next != &tree_list) {
+ struct audit_tree *tree;
+ struct path path;
+ struct vfsmount *root_mnt;
+ struct node *node;
+ int err;
+
+ tree = container_of(cursor.next, struct audit_tree, list);
+ get_tree(tree);
+ list_del(&cursor);
+ list_add(&cursor, &tree->list);
+ mutex_unlock(&audit_filter_mutex);
+
+ err = kern_path(tree->pathname, 0, &path);
+ if (err)
+ goto skip_it;
+
+ root_mnt = collect_mounts(&path);
+ path_put(&path);
+ if (IS_ERR(root_mnt))
+ goto skip_it;
+
+ spin_lock(&hash_lock);
+ list_for_each_entry(node, &tree->chunks, list) {
+ struct audit_chunk *chunk = find_chunk(node);
+ /* this could be NULL if the watch is dying else where... */
+ node->index |= 1U<<31;
+ if (iterate_mounts(compare_root,
+ (void *)(chunk->key),
+ root_mnt))
+ node->index &= ~(1U<<31);
+ }
+ spin_unlock(&hash_lock);
+ trim_marked(tree);
+ drop_collected_mounts(root_mnt);
+skip_it:
+ put_tree(tree);
+ mutex_lock(&audit_filter_mutex);
+ }
+ list_del(&cursor);
+ mutex_unlock(&audit_filter_mutex);
+}
+
+int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
+{
+
+ if (pathname[0] != '/' ||
+ rule->listnr != AUDIT_FILTER_EXIT ||
+ op != Audit_equal ||
+ rule->inode_f || rule->watch || rule->tree)
+ return -EINVAL;
+ rule->tree = alloc_tree(pathname);
+ if (!rule->tree)
+ return -ENOMEM;
+ return 0;
+}
+
+void audit_put_tree(struct audit_tree *tree)
+{
+ put_tree(tree);
+}
+
+static int tag_mount(struct vfsmount *mnt, void *arg)
+{
+ return tag_chunk(d_backing_inode(mnt->mnt_root), arg);
+}
+
+/*
+ * That gets run when evict_chunk() ends up needing to kill audit_tree.
+ * Runs from a separate thread.
+ */
+static int prune_tree_thread(void *unused)
+{
+ for (;;) {
+ if (list_empty(&prune_list)) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule();
+ }
+
+ audit_ctl_lock();
+ mutex_lock(&audit_filter_mutex);
+
+ while (!list_empty(&prune_list)) {
+ struct audit_tree *victim;
+
+ victim = list_entry(prune_list.next,
+ struct audit_tree, list);
+ list_del_init(&victim->list);
+
+ mutex_unlock(&audit_filter_mutex);
+
+ prune_one(victim);
+
+ mutex_lock(&audit_filter_mutex);
+ }
+
+ mutex_unlock(&audit_filter_mutex);
+ audit_ctl_unlock();
+ }
+ return 0;
+}
+
+static int audit_launch_prune(void)
+{
+ if (prune_thread)
+ return 0;
+ prune_thread = kthread_run(prune_tree_thread, NULL,
+ "audit_prune_tree");
+ if (IS_ERR(prune_thread)) {
+ pr_err("cannot start thread audit_prune_tree");
+ prune_thread = NULL;
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+/* called with audit_filter_mutex */
+int audit_add_tree_rule(struct audit_krule *rule)
+{
+ struct audit_tree *seed = rule->tree, *tree;
+ struct path path;
+ struct vfsmount *mnt;
+ int err;
+
+ rule->tree = NULL;
+ list_for_each_entry(tree, &tree_list, list) {
+ if (!strcmp(seed->pathname, tree->pathname)) {
+ put_tree(seed);
+ rule->tree = tree;
+ list_add(&rule->rlist, &tree->rules);
+ return 0;
+ }
+ }
+ tree = seed;
+ list_add(&tree->list, &tree_list);
+ list_add(&rule->rlist, &tree->rules);
+ /* do not set rule->tree yet */
+ mutex_unlock(&audit_filter_mutex);
+
+ if (unlikely(!prune_thread)) {
+ err = audit_launch_prune();
+ if (err)
+ goto Err;
+ }
+
+ err = kern_path(tree->pathname, 0, &path);
+ if (err)
+ goto Err;
+ mnt = collect_mounts(&path);
+ path_put(&path);
+ if (IS_ERR(mnt)) {
+ err = PTR_ERR(mnt);
+ goto Err;
+ }
+
+ get_tree(tree);
+ err = iterate_mounts(tag_mount, tree, mnt);
+ drop_collected_mounts(mnt);
+
+ if (!err) {
+ struct node *node;
+ spin_lock(&hash_lock);
+ list_for_each_entry(node, &tree->chunks, list)
+ node->index &= ~(1U<<31);
+ spin_unlock(&hash_lock);
+ } else {
+ trim_marked(tree);
+ goto Err;
+ }
+
+ mutex_lock(&audit_filter_mutex);
+ if (list_empty(&rule->rlist)) {
+ put_tree(tree);
+ return -ENOENT;
+ }
+ rule->tree = tree;
+ put_tree(tree);
+
+ return 0;
+Err:
+ mutex_lock(&audit_filter_mutex);
+ list_del_init(&tree->list);
+ list_del_init(&tree->rules);
+ put_tree(tree);
+ return err;
+}
+
+int audit_tag_tree(char *old, char *new)
+{
+ struct list_head cursor, barrier;
+ int failed = 0;
+ struct path path1, path2;
+ struct vfsmount *tagged;
+ int err;
+
+ err = kern_path(new, 0, &path2);
+ if (err)
+ return err;
+ tagged = collect_mounts(&path2);
+ path_put(&path2);
+ if (IS_ERR(tagged))
+ return PTR_ERR(tagged);
+
+ err = kern_path(old, 0, &path1);
+ if (err) {
+ drop_collected_mounts(tagged);
+ return err;
+ }
+
+ mutex_lock(&audit_filter_mutex);
+ list_add(&barrier, &tree_list);
+ list_add(&cursor, &barrier);
+
+ while (cursor.next != &tree_list) {
+ struct audit_tree *tree;
+ int good_one = 0;
+
+ tree = container_of(cursor.next, struct audit_tree, list);
+ get_tree(tree);
+ list_del(&cursor);
+ list_add(&cursor, &tree->list);
+ mutex_unlock(&audit_filter_mutex);
+
+ err = kern_path(tree->pathname, 0, &path2);
+ if (!err) {
+ good_one = path_is_under(&path1, &path2);
+ path_put(&path2);
+ }
+
+ if (!good_one) {
+ put_tree(tree);
+ mutex_lock(&audit_filter_mutex);
+ continue;
+ }
+
+ failed = iterate_mounts(tag_mount, tree, tagged);
+ if (failed) {
+ put_tree(tree);
+ mutex_lock(&audit_filter_mutex);
+ break;
+ }
+
+ mutex_lock(&audit_filter_mutex);
+ spin_lock(&hash_lock);
+ if (!tree->goner) {
+ list_del(&tree->list);
+ list_add(&tree->list, &tree_list);
+ }
+ spin_unlock(&hash_lock);
+ put_tree(tree);
+ }
+
+ while (barrier.prev != &tree_list) {
+ struct audit_tree *tree;
+
+ tree = container_of(barrier.prev, struct audit_tree, list);
+ get_tree(tree);
+ list_del(&tree->list);
+ list_add(&tree->list, &barrier);
+ mutex_unlock(&audit_filter_mutex);
+
+ if (!failed) {
+ struct node *node;
+ spin_lock(&hash_lock);
+ list_for_each_entry(node, &tree->chunks, list)
+ node->index &= ~(1U<<31);
+ spin_unlock(&hash_lock);
+ } else {
+ trim_marked(tree);
+ }
+
+ put_tree(tree);
+ mutex_lock(&audit_filter_mutex);
+ }
+ list_del(&barrier);
+ list_del(&cursor);
+ mutex_unlock(&audit_filter_mutex);
+ path_put(&path1);
+ drop_collected_mounts(tagged);
+ return failed;
+}
+
+
+static void audit_schedule_prune(void)
+{
+ wake_up_process(prune_thread);
+}
+
+/*
+ * ... and that one is done if evict_chunk() decides to delay until the end
+ * of syscall. Runs synchronously.
+ */
+void audit_kill_trees(struct audit_context *context)
+{
+ struct list_head *list = &context->killed_trees;
+
+ audit_ctl_lock();
+ mutex_lock(&audit_filter_mutex);
+
+ while (!list_empty(list)) {
+ struct audit_tree *victim;
+
+ victim = list_entry(list->next, struct audit_tree, list);
+ kill_rules(context, victim);
+ list_del_init(&victim->list);
+
+ mutex_unlock(&audit_filter_mutex);
+
+ prune_one(victim);
+
+ mutex_lock(&audit_filter_mutex);
+ }
+
+ mutex_unlock(&audit_filter_mutex);
+ audit_ctl_unlock();
+}
+
+/*
+ * Here comes the stuff asynchronous to auditctl operations
+ */
+
+static void evict_chunk(struct audit_chunk *chunk)
+{
+ struct audit_tree *owner;
+ struct list_head *postponed = audit_killed_trees();
+ int need_prune = 0;
+ int n;
+
+ mutex_lock(&audit_filter_mutex);
+ spin_lock(&hash_lock);
+ while (!list_empty(&chunk->trees)) {
+ owner = list_entry(chunk->trees.next,
+ struct audit_tree, same_root);
+ owner->goner = 1;
+ owner->root = NULL;
+ list_del_init(&owner->same_root);
+ spin_unlock(&hash_lock);
+ if (!postponed) {
+ kill_rules(audit_context(), owner);
+ list_move(&owner->list, &prune_list);
+ need_prune = 1;
+ } else {
+ list_move(&owner->list, postponed);
+ }
+ spin_lock(&hash_lock);
+ }
+ list_del_rcu(&chunk->hash);
+ for (n = 0; n < chunk->count; n++)
+ list_del_init(&chunk->owners[n].list);
+ spin_unlock(&hash_lock);
+ mutex_unlock(&audit_filter_mutex);
+ if (need_prune)
+ audit_schedule_prune();
+}
+
+static int audit_tree_handle_event(struct fsnotify_mark *mark, u32 mask,
+ struct inode *inode, struct inode *dir,
+ const struct qstr *file_name, u32 cookie)
+{
+ return 0;
+}
+
+static void audit_tree_freeing_mark(struct fsnotify_mark *mark,
+ struct fsnotify_group *group)
+{
+ struct audit_chunk *chunk;
+
+ mutex_lock(&mark->group->mark_mutex);
+ spin_lock(&hash_lock);
+ chunk = mark_chunk(mark);
+ replace_mark_chunk(mark, NULL);
+ spin_unlock(&hash_lock);
+ mutex_unlock(&mark->group->mark_mutex);
+ if (chunk) {
+ evict_chunk(chunk);
+ audit_mark_put_chunk(chunk);
+ }
+
+ /*
+ * We are guaranteed to have at least one reference to the mark from
+ * either the inode or the caller of fsnotify_destroy_mark().
+ */
+ BUG_ON(refcount_read(&mark->refcnt) < 1);
+}
+
+static const struct fsnotify_ops audit_tree_ops = {
+ .handle_inode_event = audit_tree_handle_event,
+ .freeing_mark = audit_tree_freeing_mark,
+ .free_mark = audit_tree_destroy_watch,
+};
+
+static int __init audit_tree_init(void)
+{
+ int i;
+
+ audit_tree_mark_cachep = KMEM_CACHE(audit_tree_mark, SLAB_PANIC);
+
+ audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
+ if (IS_ERR(audit_tree_group))
+ audit_panic("cannot initialize fsnotify group for rectree watches");
+
+ for (i = 0; i < HASH_SIZE; i++)
+ INIT_LIST_HEAD(&chunk_hash_heads[i]);
+
+ return 0;
+}
+__initcall(audit_tree_init);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-07 01:46:16 +0000