apparmor: move to per loaddata files, instead of replicating in profiles

The loaddata sets cover more than just a single profile and should
be tracked at the ns level. Move the load data files under the namespace
and reference the files from the profiles via a symlink.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Reviewed-by: Seth Arnold <seth.arnold@canonical.com>
Reviewed-by: Kees Cook <keescook@chromium.org>

security/apparmor/include/apparmorfs.h

@@ -106,6 +106,7 @@ enum aafs_prof_type {
 #define prof_dir(X) ((X)->dents[AAFS_PROF_DIR])
 #define prof_child_dir(X) ((X)->dents[AAFS_PROF_PROFS])
 
+void __aa_bump_ns_revision(struct aa_ns *ns);
 void __aa_fs_profile_rmdir(struct aa_profile *profile);
 void __aa_fs_profile_migrate_dents(struct aa_profile *old,
 				   struct aa_profile *new);
@@ -114,4 +115,8 @@ void __aa_fs_ns_rmdir(struct aa_ns *ns);
 int __aa_fs_ns_mkdir(struct aa_ns *ns, struct dentry *parent,
 		     const char *name);
 
+struct aa_loaddata;
+void __aa_fs_remove_rawdata(struct aa_loaddata *rawdata);
+int __aa_fs_create_rawdata(struct aa_ns *ns, struct aa_loaddata *rawdata);
+
 #endif /* __AA_APPARMORFS_H */

security/apparmor/include/policy_ns.h

@@ -68,6 +68,9 @@ struct aa_ns {
 	atomic_t uniq_null;
 	long uniq_id;
 	int level;
+	long revision;
+
+	struct list_head rawdata_list;
 
 	struct dentry *dents[AAFS_NS_SIZEOF];
 };

security/apparmor/include/policy_unpack.h

@@ -17,6 +17,8 @@
 
 #include <linux/list.h>
 #include <linux/kref.h>
+#include <linux/dcache.h>
+#include <linux/workqueue.h>
 
 struct aa_load_ent {
 	struct list_head list;
@@ -36,26 +38,84 @@ struct aa_load_ent *aa_load_ent_alloc(void);
 #define PACKED_MODE_KILL	2
 #define PACKED_MODE_UNCONFINED	3
 
-/* struct aa_loaddata - buffer of policy load data set */
+struct aa_ns;
+
+enum {
+	AAFS_LOADDATA_ABI = 0,
+	AAFS_LOADDATA_REVISION,
+	AAFS_LOADDATA_HASH,
+	AAFS_LOADDATA_DATA,
+	AAFS_LOADDATA_DIR,		/* must be last actual entry */
+	AAFS_LOADDATA_NDENTS		/* count of entries */
+};
+
+/*
+ * struct aa_loaddata - buffer of policy raw_data set
+ *
+ * there is no loaddata ref for being on ns list, nor a ref from
+ * d_inode(@dentry) when grab a ref from these, @ns->lock must be held
+ * && __aa_get_loaddata() needs to be used, and the return value
+ * checked, if NULL the loaddata is already being reaped and should be
+ * considered dead.
+ */
 struct aa_loaddata {
 	struct kref count;
+	struct list_head list;
+	struct work_struct work;
+	struct dentry *dents[AAFS_LOADDATA_NDENTS];
+	struct aa_ns *ns;
+	char *name;
 	size_t size;
+	long revision;			/* the ns policy revision this caused */
 	int abi;
 	unsigned char *hash;
+
 	char data[];
 };
 
 int aa_unpack(struct aa_loaddata *udata, struct list_head *lh, const char **ns);
 
+/**
+ * __aa_get_loaddata - get a reference count to uncounted data reference
+ * @data: reference to get a count on
+ *
+ * Returns: pointer to reference OR NULL if race is lost and reference is
+ *          being repeated.
+ * Requires: @data->ns->lock held, and the return code MUST be checked
+ *
+ * Use only from inode->i_private and @data->list found references
+ */
+static inline struct aa_loaddata *
+__aa_get_loaddata(struct aa_loaddata *data)
+{
+	if (data && kref_get_unless_zero(&(data->count)))
+		return data;
+
+	return NULL;
+}
+
+/**
+ * aa_get_loaddata - get a reference count from a counted data reference
+ * @data: reference to get a count on
+ *
+ * Returns: point to reference
+ * Requires: @data to have a valid reference count on it. It is a bug
+ *           if the race to reap can be encountered when it is used.
+ */
 static inline struct aa_loaddata *
 aa_get_loaddata(struct aa_loaddata *data)
 {
-	if (data)
-		kref_get(&(data->count));
-	return data;
+	struct aa_loaddata *tmp = __aa_get_loaddata(data);
+
+	AA_BUG(data && !tmp);
+
+	return tmp;
 }
 
+void __aa_loaddata_update(struct aa_loaddata *data, long revision);
+bool aa_rawdata_eq(struct aa_loaddata *l, struct aa_loaddata *r);
 void aa_loaddata_kref(struct kref *kref);
+struct aa_loaddata *aa_loaddata_alloc(size_t size);
 static inline void aa_put_loaddata(struct aa_loaddata *data)
 {
 	if (data)

security/apparmor/policy.c

@@ -840,10 +840,13 @@ ssize_t aa_replace_profiles(struct aa_ns *view, struct aa_profile *profile,
 	const char *ns_name, *info = NULL;
 	struct aa_ns *ns = NULL;
 	struct aa_load_ent *ent, *tmp;
+	struct aa_loaddata *rawdata_ent;
 	const char *op = OP_PROF_REPL;
 	ssize_t count, error;
+
 	LIST_HEAD(lh);
 
+	aa_get_loaddata(udata);
 	/* released below */
 	error = aa_unpack(udata, &lh, &ns_name);
 	if (error)
@@ -887,9 +890,24 @@ ssize_t aa_replace_profiles(struct aa_ns *view, struct aa_profile *profile,
 		ns = aa_get_ns(view);
 
 	mutex_lock(&ns->lock);
+	/* check for duplicate rawdata blobs: space and file dedup */
+	list_for_each_entry(rawdata_ent, &ns->rawdata_list, list) {
+		if (aa_rawdata_eq(rawdata_ent, udata)) {
+			struct aa_loaddata *tmp;
+
+			tmp = __aa_get_loaddata(rawdata_ent);
+			/* check we didn't fail the race */
+			if (tmp) {
+				aa_put_loaddata(udata);
+				udata = tmp;
+				break;
+			}
+		}
+	}
 	/* setup parent and ns info */
 	list_for_each_entry(ent, &lh, list) {
 		struct aa_policy *policy;
+
 		ent->new->rawdata = aa_get_loaddata(udata);
 		error = __lookup_replace(ns, ent->new->base.hname, noreplace,
 					 &ent->old, &info);
@@ -929,6 +947,14 @@ ssize_t aa_replace_profiles(struct aa_ns *view, struct aa_profile *profile,
 	}
 
 	/* create new fs entries for introspection if needed */
+	if (!udata->dents[AAFS_LOADDATA_DIR]) {
+		error = __aa_fs_create_rawdata(ns, udata);
+		if (error) {
+			info = "failed to create raw_data dir and files";
+			ent = NULL;
+			goto fail_lock;
+		}
+	}
 	list_for_each_entry(ent, &lh, list) {
 		if (ent->old) {
 			/* inherit old interface files */
@@ -955,10 +981,24 @@ ssize_t aa_replace_profiles(struct aa_ns *view, struct aa_profile *profile,
 	}
 
 	/* Done with checks that may fail - do actual replacement */
+	__aa_bump_ns_revision(ns);
+	__aa_loaddata_update(udata, ns->revision);
 	list_for_each_entry_safe(ent, tmp, &lh, list) {
 		list_del_init(&ent->list);
 		op = (!ent->old && !ent->rename) ? OP_PROF_LOAD : OP_PROF_REPL;
 
+		if (ent->old && ent->old->rawdata == ent->new->rawdata) {
+			/* dedup actual profile replacement */
+			audit_policy(profile, op, ns_name, ent->new->base.hname,
+				     "same as current profile, skipping",
+				     error);
+			goto skip;
+		}
+
+		/*
+		 * TODO: finer dedup based on profile range in data. Load set
+		 * can differ but profile may remain unchanged
+		 */
 		audit_policy(profile, op, NULL, ent->new->base.hname,
 			     NULL, error);
 
@@ -998,12 +1038,14 @@ ssize_t aa_replace_profiles(struct aa_ns *view, struct aa_profile *profile,
 					   aa_get_profile(ent->new));
 			__list_add_profile(&ns->base.profiles, ent->new);
 		}
+	skip:
 		aa_load_ent_free(ent);
 	}
 	mutex_unlock(&ns->lock);
 
 out:
 	aa_put_ns(ns);
+	aa_put_loaddata(udata);
 
 	if (error)
 		return error;
@@ -1013,7 +1055,7 @@ ssize_t aa_replace_profiles(struct aa_ns *view, struct aa_profile *profile,
 	mutex_unlock(&ns->lock);
 
 	/* audit cause of failure */
-	op = (!ent->old) ? OP_PROF_LOAD : OP_PROF_REPL;
+	op = (ent && !ent->old) ? OP_PROF_LOAD : OP_PROF_REPL;
 fail:
 	audit_policy(profile, op, ns_name, ent ? ent->new->base.hname : NULL,
 		     info, error);
@@ -1085,6 +1127,7 @@ ssize_t aa_remove_profiles(struct aa_ns *view, struct aa_profile *subj,
 		/* remove namespace - can only happen if fqname[0] == ':' */
 		mutex_lock(&ns->parent->lock);
 		__aa_remove_ns(ns);
+		__aa_bump_ns_revision(ns);
 		mutex_unlock(&ns->parent->lock);
 	} else {
 		/* remove profile */
@@ -1097,6 +1140,7 @@ ssize_t aa_remove_profiles(struct aa_ns *view, struct aa_profile *subj,
 		}
 		name = profile->base.hname;
 		__remove_profile(profile);
+		__aa_bump_ns_revision(ns);
 		mutex_unlock(&ns->lock);
 	}
 

security/apparmor/policy_ns.c

@@ -99,6 +99,7 @@ static struct aa_ns *alloc_ns(const char *prefix, const char *name)
 		goto fail_ns;
 
 	INIT_LIST_HEAD(&ns->sub_ns);
+	INIT_LIST_HEAD(&ns->rawdata_list);
 	mutex_init(&ns->lock);
 
 	/* released by aa_free_ns() */

security/apparmor/policy_unpack.c

@@ -122,16 +122,73 @@ static int audit_iface(struct aa_profile *new, const char *ns_name,
 	return aa_audit(AUDIT_APPARMOR_STATUS, profile, &sa, audit_cb);
 }
 
+void __aa_loaddata_update(struct aa_loaddata *data, long revision)
+{
+	AA_BUG(!data);
+	AA_BUG(!data->ns);
+	AA_BUG(!data->dents[AAFS_LOADDATA_REVISION]);
+	AA_BUG(!mutex_is_locked(&data->ns->lock));
+	AA_BUG(data->revision > revision);
+
+	data->revision = revision;
+	d_inode(data->dents[AAFS_LOADDATA_DIR])->i_mtime =
+		current_time(d_inode(data->dents[AAFS_LOADDATA_DIR]));
+	d_inode(data->dents[AAFS_LOADDATA_REVISION])->i_mtime =
+		current_time(d_inode(data->dents[AAFS_LOADDATA_REVISION]));
+}
+
+bool aa_rawdata_eq(struct aa_loaddata *l, struct aa_loaddata *r)
+{
+	if (l->size != r->size)
+		return false;
+	if (aa_g_hash_policy && memcmp(l->hash, r->hash, aa_hash_size()) != 0)
+		return false;
+	return memcmp(l->data, r->data, r->size) == 0;
+}
+
+/*
+ * need to take the ns mutex lock which is NOT safe most places that
+ * put_loaddata is called, so we have to delay freeing it
+ */
+static void do_loaddata_free(struct work_struct *work)
+{
+	struct aa_loaddata *d = container_of(work, struct aa_loaddata, work);
+	struct aa_ns *ns = aa_get_ns(d->ns);
+
+	if (ns) {
+		mutex_lock(&ns->lock);
+		__aa_fs_remove_rawdata(d);
+		mutex_unlock(&ns->lock);
+		aa_put_ns(ns);
+	}
+
+	kzfree(d->hash);
+	kfree(d->name);
+	kvfree(d);
+}
+
 void aa_loaddata_kref(struct kref *kref)
 {
 	struct aa_loaddata *d = container_of(kref, struct aa_loaddata, count);
 
 	if (d) {
-		kzfree(d->hash);
-		kvfree(d);
+		INIT_WORK(&d->work, do_loaddata_free);
+		schedule_work(&d->work);
 	}
 }
 
+struct aa_loaddata *aa_loaddata_alloc(size_t size)
+{
+	struct aa_loaddata *d = kvzalloc(sizeof(*d) + size, GFP_KERNEL);
+
+	if (d == NULL)
+		return ERR_PTR(-ENOMEM);
+	kref_init(&d->count);
+	INIT_LIST_HEAD(&d->list);
+
+	return d;
+}
+
 /* test if read will be in packed data bounds */
 static bool inbounds(struct aa_ext *e, size_t size)
 {