auditfilter.c

linux 2.6.19 kernel source code before patching

			}
			if (err) {
				kfree(str);
				goto exit_free;
			} else
				f->se_str = str;
			break;
		case AUDIT_WATCH:
			str = audit_unpack_string(&bufp, &remain, f->val);
			if (IS_ERR(str))
				goto exit_free;
			entry->rule.buflen += f->val;

			err = audit_to_watch(&entry->rule, str, f->val, f->op);
			if (err) {
				kfree(str);
				goto exit_free;
			}
			break;
		case AUDIT_INODE:
			err = audit_to_inode(&entry->rule, f);
			if (err)
				goto exit_free;
			break;
		case AUDIT_FILTERKEY:
			err = -EINVAL;
			if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN)
				goto exit_free;
			str = audit_unpack_string(&bufp, &remain, f->val);
			if (IS_ERR(str))
				goto exit_free;
			entry->rule.buflen += f->val;
			entry->rule.filterkey = str;
			break;
		case AUDIT_PERM:
			if (f->val & ~15)
				goto exit_free;
			break;
		default:
			goto exit_free;
		}
	}

	f = entry->rule.inode_f;
	if (f) {
		switch(f->op) {
		case AUDIT_NOT_EQUAL:
			entry->rule.inode_f = NULL;
		case AUDIT_EQUAL:
			break;
		default:
			err = -EINVAL;
			goto exit_free;
		}
	}

exit_nofree:
	return entry;

exit_free:
	audit_free_rule(entry);
	return ERR_PTR(err);
}

/* Pack a filter field's string representation into data block. */
static inline size_t audit_pack_string(void **bufp, char *str)
{
	size_t len = strlen(str);

	memcpy(*bufp, str, len);
	*bufp += len;

	return len;
}

/* Translate kernel rule respresentation to struct audit_rule.
 * Exists for backward compatibility with userspace. */
static struct audit_rule *audit_krule_to_rule(struct audit_krule *krule)
{
	struct audit_rule *rule;
	int i;

	rule = kzalloc(sizeof(*rule), GFP_KERNEL);
	if (unlikely(!rule))
		return NULL;

	rule->flags = krule->flags | krule->listnr;
	rule->action = krule->action;
	rule->field_count = krule->field_count;
	for (i = 0; i < rule->field_count; i++) {
		rule->values[i] = krule->fields[i].val;
		rule->fields[i] = krule->fields[i].type;

		if (krule->vers_ops == 1) {
			if (krule->fields[i].op & AUDIT_NOT_EQUAL)
				rule->fields[i] |= AUDIT_NEGATE;
		} else {
			rule->fields[i] |= krule->fields[i].op;
		}
	}
	for (i = 0; i < AUDIT_BITMASK_SIZE; i++) rule->mask[i] = krule->mask[i];

	return rule;
}

/* Translate kernel rule respresentation to struct audit_rule_data. */
static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
{
	struct audit_rule_data *data;
	void *bufp;
	int i;

	data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
	if (unlikely(!data))
		return NULL;
	memset(data, 0, sizeof(*data));

	data->flags = krule->flags | krule->listnr;
	data->action = krule->action;
	data->field_count = krule->field_count;
	bufp = data->buf;
	for (i = 0; i < data->field_count; i++) {
		struct audit_field *f = &krule->fields[i];

		data->fields[i] = f->type;
		data->fieldflags[i] = f->op;
		switch(f->type) {
		case AUDIT_SUBJ_USER:
		case AUDIT_SUBJ_ROLE:
		case AUDIT_SUBJ_TYPE:
		case AUDIT_SUBJ_SEN:
		case AUDIT_SUBJ_CLR:
		case AUDIT_OBJ_USER:
		case AUDIT_OBJ_ROLE:
		case AUDIT_OBJ_TYPE:
		case AUDIT_OBJ_LEV_LOW:
		case AUDIT_OBJ_LEV_HIGH:
			data->buflen += data->values[i] =
				audit_pack_string(&bufp, f->se_str);
			break;
		case AUDIT_WATCH:
			data->buflen += data->values[i] =
				audit_pack_string(&bufp, krule->watch->path);
			break;
		case AUDIT_FILTERKEY:
			data->buflen += data->values[i] =
				audit_pack_string(&bufp, krule->filterkey);
			break;
		default:
			data->values[i] = f->val;
		}
	}
	for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i];

	return data;
}

/* Compare two rules in kernel format.  Considered success if rules
 * don't match. */
static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
{
	int i;

	if (a->flags != b->flags ||
	    a->listnr != b->listnr ||
	    a->action != b->action ||
	    a->field_count != b->field_count)
		return 1;

	for (i = 0; i < a->field_count; i++) {
		if (a->fields[i].type != b->fields[i].type ||
		    a->fields[i].op != b->fields[i].op)
			return 1;

		switch(a->fields[i].type) {
		case AUDIT_SUBJ_USER:
		case AUDIT_SUBJ_ROLE:
		case AUDIT_SUBJ_TYPE:
		case AUDIT_SUBJ_SEN:
		case AUDIT_SUBJ_CLR:
		case AUDIT_OBJ_USER:
		case AUDIT_OBJ_ROLE:
		case AUDIT_OBJ_TYPE:
		case AUDIT_OBJ_LEV_LOW:
		case AUDIT_OBJ_LEV_HIGH:
			if (strcmp(a->fields[i].se_str, b->fields[i].se_str))
				return 1;
			break;
		case AUDIT_WATCH:
			if (strcmp(a->watch->path, b->watch->path))
				return 1;
			break;
		case AUDIT_FILTERKEY:
			/* both filterkeys exist based on above type compare */
			if (strcmp(a->filterkey, b->filterkey))
				return 1;
			break;
		default:
			if (a->fields[i].val != b->fields[i].val)
				return 1;
		}
	}

	for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
		if (a->mask[i] != b->mask[i])
			return 1;

	return 0;
}

/* Duplicate the given audit watch.  The new watch's rules list is initialized
 * to an empty list and wlist is undefined. */
static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
{
	char *path;
	struct audit_watch *new;

	path = kstrdup(old->path, GFP_KERNEL);
	if (unlikely(!path))
		return ERR_PTR(-ENOMEM);

	new = audit_init_watch(path);
	if (unlikely(IS_ERR(new))) {
		kfree(path);
		goto out;
	}

	new->dev = old->dev;
	new->ino = old->ino;
	get_inotify_watch(&old->parent->wdata);
	new->parent = old->parent;

out:
	return new;
}

/* Duplicate selinux field information.  The se_rule is opaque, so must be
 * re-initialized. */
static inline int audit_dupe_selinux_field(struct audit_field *df,
					   struct audit_field *sf)
{
	int ret = 0;
	char *se_str;

	/* our own copy of se_str */
	se_str = kstrdup(sf->se_str, GFP_KERNEL);
	if (unlikely(!se_str))
		return -ENOMEM;
	df->se_str = se_str;

	/* our own (refreshed) copy of se_rule */
	ret = selinux_audit_rule_init(df->type, df->op, df->se_str,
				      &df->se_rule);
	/* Keep currently invalid fields around in case they
	 * become valid after a policy reload. */
	if (ret == -EINVAL) {
		printk(KERN_WARNING "audit rule for selinux \'%s\' is "
		       "invalid\n", df->se_str);
		ret = 0;
	}

	return ret;
}

/* Duplicate an audit rule.  This will be a deep copy with the exception
 * of the watch - that pointer is carried over.  The selinux specific fields
 * will be updated in the copy.  The point is to be able to replace the old
 * rule with the new rule in the filterlist, then free the old rule.
 * The rlist element is undefined; list manipulations are handled apart from
 * the initial copy. */
static struct audit_entry *audit_dupe_rule(struct audit_krule *old,
					   struct audit_watch *watch)
{
	u32 fcount = old->field_count;
	struct audit_entry *entry;
	struct audit_krule *new;
	char *fk;
	int i, err = 0;

	entry = audit_init_entry(fcount);
	if (unlikely(!entry))
		return ERR_PTR(-ENOMEM);

	new = &entry->rule;
	new->vers_ops = old->vers_ops;
	new->flags = old->flags;
	new->listnr = old->listnr;
	new->action = old->action;
	for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
		new->mask[i] = old->mask[i];
	new->buflen = old->buflen;
	new->inode_f = old->inode_f;
	new->watch = NULL;
	new->field_count = old->field_count;
	memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);

	/* deep copy this information, updating the se_rule fields, because
	 * the originals will all be freed when the old rule is freed. */
	for (i = 0; i < fcount; i++) {
		switch (new->fields[i].type) {
		case AUDIT_SUBJ_USER:
		case AUDIT_SUBJ_ROLE:
		case AUDIT_SUBJ_TYPE:
		case AUDIT_SUBJ_SEN:
		case AUDIT_SUBJ_CLR:
		case AUDIT_OBJ_USER:
		case AUDIT_OBJ_ROLE:
		case AUDIT_OBJ_TYPE:
		case AUDIT_OBJ_LEV_LOW:
		case AUDIT_OBJ_LEV_HIGH:
			err = audit_dupe_selinux_field(&new->fields[i],
						       &old->fields[i]);
			break;
		case AUDIT_FILTERKEY:
			fk = kstrdup(old->filterkey, GFP_KERNEL);
			if (unlikely(!fk))
				err = -ENOMEM;
			else
				new->filterkey = fk;
		}
		if (err) {
			audit_free_rule(entry);
			return ERR_PTR(err);
		}
	}

	if (watch) {
		audit_get_watch(watch);
		new->watch = watch;
	}

	return entry;
}

/* Update inode info in audit rules based on filesystem event. */
static void audit_update_watch(struct audit_parent *parent,
			       const char *dname, dev_t dev,
			       unsigned long ino, unsigned invalidating)
{
	struct audit_watch *owatch, *nwatch, *nextw;
	struct audit_krule *r, *nextr;
	struct audit_entry *oentry, *nentry;
	struct audit_buffer *ab;

	mutex_lock(&audit_filter_mutex);
	list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
		if (audit_compare_dname_path(dname, owatch->path, NULL))
			continue;

		/* If the update involves invalidating rules, do the inode-based
		 * filtering now, so we don't omit records. */
		if (invalidating && current->audit_context &&
		    audit_filter_inodes(current, current->audit_context) == AUDIT_RECORD_CONTEXT)
			audit_set_auditable(current->audit_context);

		nwatch = audit_dupe_watch(owatch);
		if (unlikely(IS_ERR(nwatch))) {
			mutex_unlock(&audit_filter_mutex);
			audit_panic("error updating watch, skipping");
			return;
		}
		nwatch->dev = dev;
		nwatch->ino = ino;

		list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {

			oentry = container_of(r, struct audit_entry, rule);
			list_del(&oentry->rule.rlist);
			list_del_rcu(&oentry->list);

			nentry = audit_dupe_rule(&oentry->rule, nwatch);
			if (unlikely(IS_ERR(nentry)))
				audit_panic("error updating watch, removing");
			else {
				int h = audit_hash_ino((u32)ino);
				list_add(&nentry->rule.rlist, &nwatch->rules);
				list_add_rcu(&nentry->list, &audit_inode_hash[h]);
			}

			call_rcu(&oentry->rcu, audit_free_rule_rcu);
		}

		ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
		audit_log_format(ab, "op=updated rules specifying path=");
		audit_log_untrustedstring(ab, owatch->path);
		audit_log_format(ab, " with dev=%u ino=%lu\n", dev, ino);
		audit_log_format(ab, " list=%d res=1", r->listnr);
		audit_log_end(ab);

		audit_remove_watch(owatch);
		goto add_watch_to_parent; /* event applies to a single watch */
	}
	mutex_unlock(&audit_filter_mutex);
	return;

add_watch_to_parent:
	list_add(&nwatch->wlist, &parent->watches);
	mutex_unlock(&audit_filter_mutex);
	return;
}

/* Remove all watches & rules associated with a parent that is going away. */
static void audit_remove_parent_watches(struct audit_parent *parent)
{
	struct audit_watch *w, *nextw;
	struct audit_krule *r, *nextr;
	struct audit_entry *e;
	struct audit_buffer *ab;

	mutex_lock(&audit_filter_mutex);
	parent->flags |= AUDIT_PARENT_INVALID;
	list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
		list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
			e = container_of(r, struct audit_entry, rule);

			ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
			audit_log_format(ab, "op=remove rule path=");
			audit_log_untrustedstring(ab, w->path);
			if (r->filterkey) {
				audit_log_format(ab, " key=");
				audit_log_untrustedstring(ab, r->filterkey);
			} else
				audit_log_format(ab, " key=(null)");
			audit_log_format(ab, " list=%d res=1", r->listnr);
			audit_log_end(ab);

			list_del(&r->rlist);
			list_del_rcu(&e->list);
			call_rcu(&e->rcu, audit_free_rule_rcu);
		}
		audit_remove_watch(w);
	}
	mutex_unlock(&audit_filter_mutex);
}

/* Unregister inotify watches for parents on in_list.
 * Generates an IN_IGNORED event. */
static void audit_inotify_unregister(struct list_head *in_list)
{
	struct audit_parent *p, *n;

	list_for_each_entry_safe(p, n, in_list, ilist) {
		list_del(&p->ilist);
		inotify_rm_watch(audit_ih, &p->wdata);
		/* the put matching the get in audit_do_del_rule() */
		put_inotify_watch(&p->wdata);
	}
}

/* Find an existing audit rule.
 * Caller must hold audit_filter_mutex to prevent stale rule data. */
static struct audit_entry *audit_find_rule(struct audit_entry *entry,
					   struct list_head *list)
{
	struct audit_entry *e, *found = NULL;
	int h;

	if (entry->rule.watch) {
		/* we don't know the inode number, so must walk entire hash */
		for (h = 0; h < AUDIT_INODE_BUCKETS; h++) {
			list = &audit_inode_hash[h];
			list_for_each_entry(e, list, list)
				if (!audit_compare_rule(&entry->rule, &e->rule)) {
					found = e;
					goto out;
				}
		}
		goto out;
	}

	list_for_each_entry(e, list, list)
		if (!audit_compare_rule(&entry->rule, &e->rule)) {
			found = e;
			goto out;
		}

out:
	return found;
}

/* Get path information necessary for adding watches. */
static int audit_get_nd(char *path, struct nameidata **ndp,
			struct nameidata **ndw)
{
	struct nameidata *ndparent, *ndwatch;
	int err;

	ndparent = kmalloc(sizeof(*ndparent), GFP_KERNEL);
	if (unlikely(!ndparent))
		return -ENOMEM;

	ndwatch = kmalloc(sizeof(*ndwatch), GFP_KERNEL);
	if (unlikely(!ndwatch)) {
		kfree(ndparent);
		return -ENOMEM;
	}

	err = path_lookup(path, LOOKUP_PARENT, ndparent);
	if (err) {
		kfree(ndparent);
		kfree(ndwatch);
		return err;
	}

	err = path_lookup(path, 0, ndwatch);
	if (err) {
		kfree(ndwatch);
		ndwatch = NULL;
	}

	*ndp = ndparent;
	*ndw = ndwatch;

	return 0;
}

/* Release resources used for watch path information. */
static void audit_put_nd(struct nameidata *ndp, struct nameidata *ndw)
{
	if (ndp) {
		path_release(ndp);
		kfree(ndp);
	}
	if (ndw) {
		path_release(ndw);
		kfree(ndw);
	}
}

/* Associate the given rule with an existing parent inotify_watch.
 * Caller must hold audit_filter_mutex. */
static void audit_add_to_parent(struct audit_krule *krule,
				struct audit_parent *parent)
{
	struct audit_watch *w, *watch = krule->watch;
	int watch_found = 0;

	list_for_each_entry(w, &parent->watches, wlist) {
		if (strcmp(watch->path, w->path))
			continue;

		watch_found = 1;

		/* put krule's and initial refs to temporary watch */
		audit_put_watch(watch);
		audit_put_watch(watch);

		audit_get_watch(w);
		krule->watch = watch = w;
		break;
	}

	if (!watch_found) {
		get_inotify_watch(&parent->wdata);
		watch->parent = parent;

		list_add(&watch->wlist, &parent->watches);
	}
	list_add(&krule->rlist, &watch->rules);
}

/* Find a matching watch entry, or add this one.
 * Caller must hold audit_filter_mutex. */
static int audit_add_watch(struct audit_krule *krule, struct nameidata *ndp,
			   struct nameidata *ndw)
{
	struct audit_watch *watch = krule->watch;
	struct inotify_watch *i_watch;
	struct audit_parent *parent;
	int ret = 0;

	/* update watch filter fields */
	if (ndw) {
		watch->dev = ndw->dentry->d_inode->i_sb->s_dev;
		watch->ino = ndw->dentry->d_inode->i_ino;
	}

	/* The audit_filter_mutex must not be held during inotify calls because
	 * we hold it during inotify event callback processing.  If an existing
	 * inotify watch is found, inotify_find_watch() grabs a reference before
	 * returning.
	 */
	mutex_unlock(&audit_filter_mutex);

	if (inotify_find_watch(audit_ih, ndp->dentry->d_inode, &i_watch) < 0) {
		parent = audit_init_parent(ndp);
		if (IS_ERR(parent)) {
			/* caller expects mutex locked */
			mutex_lock(&audit_filter_mutex);
			return PTR_ERR(parent);
		}
	} else
		parent = container_of(i_watch, struct audit_parent, wdata);

	mutex_lock(&audit_filter_mutex);

	/* parent was moved before we took audit_filter_mutex */
	if (parent->flags & AUDIT_PARENT_INVALID)