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Commit 01e2b670 authored by John Johansen's avatar John Johansen
Browse files

apparmor: convert profile lists to RCU based locking 



Signed-off-by: default avatarJohn Johansen <john.johansen@canonical.com>
parent dd51c848

security/apparmor/domain.c

+10 −4
Original line number Diff line number Diff line
@@ -144,7 +144,7 @@ static struct aa_profile *__attach_match(const char *name, 
	int len = 0;

	struct aa_profile *profile, *candidate = NULL;



	list_for_each_entry(profile, head, base.list) {

	list_for_each_entry_rcu(profile, head, base.list) {

		if (profile->flags & PFLAG_NULL)

			continue;

		if (profile->xmatch && profile->xmatch_len > len) {
@@ -177,9 +177,9 @@ static struct aa_profile *find_attach(struct aa_namespace *ns, 
{

	struct aa_profile *profile;



	read_lock(&ns->lock);

	rcu_read_lock();

	profile = aa_get_profile(__attach_match(name, list));

	read_unlock(&ns->lock);

	rcu_read_unlock();



	return profile;

}
@@ -641,7 +641,10 @@ int aa_change_hat(const char *hats[], int count, u64 token, bool permtest) 
	if (count) {

		/* attempting to change into a new hat or switch to a sibling */

		struct aa_profile *root;

		root = PROFILE_IS_HAT(profile) ? profile->parent : profile;

		if (PROFILE_IS_HAT(profile))

			root = aa_get_profile_rcu(&profile->parent);

		else

			root = aa_get_profile(profile);



		/* find first matching hat */

		for (i = 0; i < count && !hat; i++)
@@ -653,6 +656,7 @@ int aa_change_hat(const char *hats[], int count, u64 token, bool permtest) 
					error = -ECHILD;

				else

					error = -ENOENT;

				aa_put_profile(root);

				goto out;

			}
@@ -667,6 +671,7 @@ int aa_change_hat(const char *hats[], int count, u64 token, bool permtest) 


			/* freed below */

			name = new_compound_name(root->base.hname, hats[0]);

			aa_put_profile(root);

			target = name;

			/* released below */

			hat = aa_new_null_profile(profile, 1);
@@ -676,6 +681,7 @@ int aa_change_hat(const char *hats[], int count, u64 token, bool permtest) 
				goto audit;

			}

		} else {

			aa_put_profile(root);

			target = hat->base.hname;

			if (!PROFILE_IS_HAT(hat)) {

				info = "target not hat";

security/apparmor/include/apparmor.h

+6 −0
Original line number Diff line number Diff line
@@ -78,6 +78,12 @@ static inline void *kvzalloc(size_t size) 
	return __aa_kvmalloc(size, __GFP_ZERO);

}



/* returns 0 if kref not incremented */

static inline int kref_get_not0(struct kref *kref)

{

	return atomic_inc_not_zero(&kref->refcount);

}



/**

 * aa_strneq - compare null terminated @str to a non null terminated substring

 * @str: a null terminated string

security/apparmor/include/policy.h

+42 −3
Original line number Diff line number Diff line
@@ -42,6 +42,8 @@ extern const char *const profile_mode_names[]; 


#define PROFILE_IS_HAT(_profile) ((_profile)->flags & PFLAG_HAT)



#define on_list_rcu(X) (!list_empty(X) && (X)->prev != LIST_POISON2)



/*

 * FIXME: currently need a clean way to replace and remove profiles as a

 * set.  It should be done at the namespace level.
@@ -75,6 +77,7 @@ struct aa_profile; 
 * @hname - The hierarchical name

 * @count: reference count of the obj

 * @list: list policy object is on

 * @rcu: rcu head used when removing from @list

 * @profiles: head of the profiles list contained in the object

 */

struct aa_policy {
@@ -83,6 +86,7 @@ struct aa_policy { 
	struct kref count;

	struct list_head list;

	struct list_head profiles;

	struct rcu_head rcu;

};



/* struct aa_ns_acct - accounting of profiles in namespace
@@ -124,7 +128,7 @@ struct aa_ns_acct { 
struct aa_namespace {

	struct aa_policy base;

	struct aa_namespace *parent;

	rwlock_t lock;

	struct mutex lock;

	struct aa_ns_acct acct;

	struct aa_profile *unconfined;

	struct list_head sub_ns;
@@ -166,7 +170,7 @@ struct aa_policydb { 
 * attachments are determined by profile X transition rules.

 *

 * The @replacedby field is write protected by the profile lock.  Reads

 * are assumed to be atomic, and are done without locking.

 * are assumed to be atomic.

 *

 * Profiles have a hierarchy where hats and children profiles keep

 * a reference to their parent.
@@ -177,7 +181,7 @@ struct aa_policydb { 
 */

struct aa_profile {

	struct aa_policy base;

	struct aa_profile *parent;

	struct aa_profile __rcu *parent;



	struct aa_namespace *ns;

	struct aa_profile *replacedby;
@@ -295,6 +299,41 @@ static inline struct aa_profile *aa_get_profile(struct aa_profile *p) 
	return p;

}



/**

 * aa_get_profile_not0 - increment refcount on profile @p found via lookup

 * @p: profile  (MAYBE NULL)

 *

 * Returns: pointer to @p if @p is NULL will return NULL

 * Requires: @p must be held with valid refcount when called

 */

static inline struct aa_profile *aa_get_profile_not0(struct aa_profile *p)

{

	if (p && kref_get_not0(&p->base.count))

		return p;



	return NULL;

}



/**

 * aa_get_profile_rcu - increment a refcount profile that can be replaced

 * @p: pointer to profile that can be replaced (NOT NULL)

 *

 * Returns: pointer to a refcounted profile.

 *     else NULL if no profile

 */

static inline struct aa_profile *aa_get_profile_rcu(struct aa_profile __rcu **p)

{

	struct aa_profile *c;



	rcu_read_lock();

	do {

		c = rcu_dereference(*p);

	} while (c && !kref_get_not0(&c->base.count));

	rcu_read_unlock();



	return c;

}



/**

 * aa_put_profile - decrement refcount on profile @p

 * @p: profile  (MAYBE NULL)

security/apparmor/policy.c

+109 −104
Original line number Diff line number Diff line
@@ -153,13 +153,13 @@ static bool policy_init(struct aa_policy *policy, const char *prefix, 
static void policy_destroy(struct aa_policy *policy)

{

	/* still contains profiles -- invalid */

	if (!list_empty(&policy->profiles)) {

	if (on_list_rcu(&policy->profiles)) {

		AA_ERROR("%s: internal error, "

			 "policy '%s' still contains profiles\n",

			 __func__, policy->name);

		BUG();

	}

	if (!list_empty(&policy->list)) {

	if (on_list_rcu(&policy->list)) {

		AA_ERROR("%s: internal error, policy '%s' still on list\n",

			 __func__, policy->name);

		BUG();
@@ -174,7 +174,7 @@ static void policy_destroy(struct aa_policy *policy) 
 * @head: list to search  (NOT NULL)

 * @name: name to search for  (NOT NULL)

 *

 * Requires: correct locks for the @head list be held

 * Requires: rcu_read_lock be held

 *

 * Returns: unrefcounted policy that match @name or NULL if not found

 */
@@ -182,7 +182,7 @@ static struct aa_policy *__policy_find(struct list_head *head, const char *name) 
{

	struct aa_policy *policy;



	list_for_each_entry(policy, head, list) {

	list_for_each_entry_rcu(policy, head, list) {

		if (!strcmp(policy->name, name))

			return policy;

	}
@@ -195,7 +195,7 @@ static struct aa_policy *__policy_find(struct list_head *head, const char *name) 
 * @str: string to search for  (NOT NULL)

 * @len: length of match required

 *

 * Requires: correct locks for the @head list be held

 * Requires: rcu_read_lock be held

 *

 * Returns: unrefcounted policy that match @str or NULL if not found

 *
@@ -207,7 +207,7 @@ static struct aa_policy *__policy_strn_find(struct list_head *head, 
{

	struct aa_policy *policy;



	list_for_each_entry(policy, head, list) {

	list_for_each_entry_rcu(policy, head, list) {

		if (aa_strneq(policy->name, str, len))

			return policy;

	}
@@ -284,7 +284,7 @@ static struct aa_namespace *alloc_namespace(const char *prefix, 
		goto fail_ns;



	INIT_LIST_HEAD(&ns->sub_ns);

	rwlock_init(&ns->lock);

	mutex_init(&ns->lock);



	/* released by free_namespace */

	ns->unconfined = aa_alloc_profile("unconfined");
@@ -350,7 +350,7 @@ void aa_free_namespace_kref(struct kref *kref) 
 *

 * Returns: unrefcounted namespace

 *

 * Requires: ns lock be held

 * Requires: rcu_read_lock be held

 */

static struct aa_namespace *__aa_find_namespace(struct list_head *head,

						const char *name)
@@ -373,9 +373,9 @@ struct aa_namespace *aa_find_namespace(struct aa_namespace *root, 
{

	struct aa_namespace *ns = NULL;



	read_lock(&root->lock);

	rcu_read_lock();

	ns = aa_get_namespace(__aa_find_namespace(&root->sub_ns, name));

	read_unlock(&root->lock);

	rcu_read_unlock();



	return ns;

}
@@ -392,7 +392,7 @@ static struct aa_namespace *aa_prepare_namespace(const char *name) 


	root = aa_current_profile()->ns;



	write_lock(&root->lock);

	mutex_lock(&root->lock);



	/* if name isn't specified the profile is loaded to the current ns */

	if (!name) {
@@ -405,31 +405,17 @@ static struct aa_namespace *aa_prepare_namespace(const char *name) 
	/* released by caller */

	ns = aa_get_namespace(__aa_find_namespace(&root->sub_ns, name));

	if (!ns) {

		/* namespace not found */

		struct aa_namespace *new_ns;

		write_unlock(&root->lock);

		new_ns = alloc_namespace(root->base.hname, name);

		if (!new_ns)

			return NULL;

		write_lock(&root->lock);

		/* test for race when new_ns was allocated */

		ns = __aa_find_namespace(&root->sub_ns, name);

		if (!ns) {

		ns = alloc_namespace(root->base.hname, name);

		if (!ns)

			goto out;

		/* add parent ref */

			new_ns->parent = aa_get_namespace(root);



			list_add(&new_ns->base.list, &root->sub_ns);

		ns->parent = aa_get_namespace(root);

		list_add_rcu(&ns->base.list, &root->sub_ns);

		/* add list ref */

			ns = aa_get_namespace(new_ns);

		} else {

			/* raced so free the new one */

			free_namespace(new_ns);

			/* get reference on namespace */

		aa_get_namespace(ns);

	}

	}

out:

	write_unlock(&root->lock);

	mutex_unlock(&root->lock);



	/* return ref */

	return ns;
@@ -447,7 +433,7 @@ out: 
static void __list_add_profile(struct list_head *list,

			       struct aa_profile *profile)

{

	list_add(&profile->base.list, list);

	list_add_rcu(&profile->base.list, list);

	/* get list reference */

	aa_get_profile(profile);

}
@@ -466,9 +452,7 @@ static void __list_add_profile(struct list_head *list, 
 */

static void __list_remove_profile(struct aa_profile *profile)

{

	list_del_init(&profile->base.list);

	if (!(profile->flags & PFLAG_NO_LIST_REF))

		/* release list reference */

	list_del_rcu(&profile->base.list);

	aa_put_profile(profile);

}
@@ -510,17 +494,40 @@ static void __ns_list_release(struct list_head *head); 
 */

static void destroy_namespace(struct aa_namespace *ns)

{

	struct aa_profile *unconfined;



	if (!ns)

		return;



	write_lock(&ns->lock);

	mutex_lock(&ns->lock);

	/* release all profiles in this namespace */

	__profile_list_release(&ns->base.profiles);



	/* release all sub namespaces */

	__ns_list_release(&ns->sub_ns);



	write_unlock(&ns->lock);

	unconfined = ns->unconfined;

	/*

	 * break the ns, unconfined profile cyclic reference and forward

	 * all new unconfined profiles requests to the parent namespace

	 * This will result in all confined tasks that have a profile

	 * being removed, inheriting the parent->unconfined profile.

	 */

	if (ns->parent)

		ns->unconfined = aa_get_profile(ns->parent->unconfined);



	/* release original ns->unconfined ref */

	aa_put_profile(unconfined);



	mutex_unlock(&ns->lock);

}



static void aa_put_ns_rcu(struct rcu_head *head)

{

	struct aa_namespace *ns = container_of(head, struct aa_namespace,

					       base.rcu);

	/* release ns->base.list ref */

	aa_put_namespace(ns);

}



/**
@@ -531,26 +538,12 @@ static void destroy_namespace(struct aa_namespace *ns) 
 */

static void __remove_namespace(struct aa_namespace *ns)

{

	struct aa_profile *unconfined = ns->unconfined;



	/* remove ns from namespace list */

	list_del_init(&ns->base.list);



	/*

	 * break the ns, unconfined profile cyclic reference and forward

	 * all new unconfined profiles requests to the parent namespace

	 * This will result in all confined tasks that have a profile

	 * being removed, inheriting the parent->unconfined profile.

	 */

	if (ns->parent)

		ns->unconfined = aa_get_profile(ns->parent->unconfined);

	list_del_rcu(&ns->base.list);



	destroy_namespace(ns);



	/* release original ns->unconfined ref */

	aa_put_profile(unconfined);

	/* release ns->base.list ref, from removal above */

	aa_put_namespace(ns);

	call_rcu(&ns->base.rcu, aa_put_ns_rcu);

}



/**
@@ -614,16 +607,9 @@ static void free_profile(struct aa_profile *profile) 
	if (!profile)

		return;



	if (!list_empty(&profile->base.list)) {

		AA_ERROR("%s: internal error, "

			 "profile '%s' still on ns list\n",

			 __func__, profile->base.name);

		BUG();

	}



	/* free children profiles */

	policy_destroy(&profile->base);

	aa_put_profile(profile->parent);

	aa_put_profile(rcu_access_pointer(profile->parent));



	aa_put_namespace(profile->ns);

	kzfree(profile->rename);
@@ -660,6 +646,16 @@ static void free_profile(struct aa_profile *profile) 
	kzfree(profile);

}



/**

 * aa_free_profile_rcu - free aa_profile by rcu (called by aa_free_profile_kref)

 * @head: rcu_head callback for freeing of a profile  (NOT NULL)

 */

static void aa_free_profile_rcu(struct rcu_head *head)

{

	struct aa_profile *p = container_of(head, struct aa_profile, base.rcu);

	free_profile(p);

}



/**

 * aa_free_profile_kref - free aa_profile by kref (called by aa_put_profile)

 * @kr: kref callback for freeing of a profile  (NOT NULL)
@@ -668,8 +664,7 @@ void aa_free_profile_kref(struct kref *kref) 
{

	struct aa_profile *p = container_of(kref, struct aa_profile,

					    base.count);



	free_profile(p);

	call_rcu(&p->base.rcu, aa_free_profile_rcu);

}



/**
@@ -733,12 +728,12 @@ struct aa_profile *aa_new_null_profile(struct aa_profile *parent, int hat) 
		profile->flags |= PFLAG_HAT;



	/* released on free_profile */

	profile->parent = aa_get_profile(parent);

	rcu_assign_pointer(profile->parent, aa_get_profile(parent));

	profile->ns = aa_get_namespace(parent->ns);



	write_lock(&profile->ns->lock);

	mutex_lock(&profile->ns->lock);

	__list_add_profile(&parent->base.profiles, profile);

	write_unlock(&profile->ns->lock);

	mutex_unlock(&profile->ns->lock);



	/* refcount released by caller */

	return profile;
@@ -754,7 +749,7 @@ fail: 
 * @head: list to search  (NOT NULL)

 * @name: name of profile (NOT NULL)

 *

 * Requires: ns lock protecting list be held

 * Requires: rcu_read_lock be held

 *

 * Returns: unrefcounted profile ptr, or NULL if not found

 */
@@ -769,7 +764,7 @@ static struct aa_profile *__find_child(struct list_head *head, const char *name) 
 * @name: name of profile (NOT NULL)

 * @len: length of @name substring to match

 *

 * Requires: ns lock protecting list be held

 * Requires: rcu_read_lock be held

 *

 * Returns: unrefcounted profile ptr, or NULL if not found

 */
@@ -790,9 +785,9 @@ struct aa_profile *aa_find_child(struct aa_profile *parent, const char *name) 
{

	struct aa_profile *profile;



	read_lock(&parent->ns->lock);

	rcu_read_lock();

	profile = aa_get_profile(__find_child(&parent->base.profiles, name));

	read_unlock(&parent->ns->lock);

	rcu_read_unlock();



	/* refcount released by caller */

	return profile;
@@ -807,7 +802,7 @@ struct aa_profile *aa_find_child(struct aa_profile *parent, const char *name) 
 * that matches hname does not need to exist, in general this

 * is used to load a new profile.

 *

 * Requires: ns->lock be held

 * Requires: rcu_read_lock be held

 *

 * Returns: unrefcounted policy or NULL if not found

 */
@@ -839,7 +834,7 @@ static struct aa_policy *__lookup_parent(struct aa_namespace *ns, 
 * @base: base list to start looking up profile name from  (NOT NULL)

 * @hname: hierarchical profile name  (NOT NULL)

 *

 * Requires: ns->lock be held

 * Requires: rcu_read_lock be held

 *

 * Returns: unrefcounted profile pointer or NULL if not found

 *
@@ -878,9 +873,11 @@ struct aa_profile *aa_lookup_profile(struct aa_namespace *ns, const char *hname) 
{

	struct aa_profile *profile;



	read_lock(&ns->lock);

	profile = aa_get_profile(__lookup_profile(&ns->base, hname));

	read_unlock(&ns->lock);

	rcu_read_lock();

	do {

		profile = __lookup_profile(&ns->base, hname);

	} while (profile && !aa_get_profile_not0(profile));

	rcu_read_unlock();



	/* the unconfined profile is not in the regular profile list */

	if (!profile && strcmp(hname, "unconfined") == 0)
@@ -1002,7 +999,7 @@ static void __replace_profile(struct aa_profile *old, struct aa_profile *new) 


	if (!list_empty(&old->base.profiles)) {

		LIST_HEAD(lh);

		list_splice_init(&old->base.profiles, &lh);

		list_splice_init_rcu(&old->base.profiles, &lh, synchronize_rcu);



		list_for_each_entry_safe(child, tmp, &lh, base.list) {

			struct aa_profile *p;
@@ -1018,20 +1015,24 @@ static void __replace_profile(struct aa_profile *old, struct aa_profile *new) 
			/* inherit @child and its children */

			/* TODO: update hname of inherited children */

			/* list refcount transferred to @new */

			list_add(&child->base.list, &new->base.profiles);

			aa_put_profile(child->parent);

			child->parent = aa_get_profile(new);

			p = rcu_dereference_protected(child->parent,

					     mutex_is_locked(&child->ns->lock));

			rcu_assign_pointer(child->parent, aa_get_profile(new));

			list_add_rcu(&child->base.list, &new->base.profiles);

			aa_put_profile(p);

		}

	}



	if (!new->parent)

		new->parent = aa_get_profile(old->parent);

	if (!rcu_access_pointer(new->parent)) {

		struct aa_profile *parent = rcu_dereference(old->parent);

		rcu_assign_pointer(new->parent, aa_get_profile(parent));

	}

	/* released by free_profile */

	old->replacedby = aa_get_profile(new);



	if (list_empty(&new->base.list)) {

		/* new is not on a list already */

		list_replace_init(&old->base.list, &new->base.list);

		list_replace_rcu(&old->base.list, &new->base.list);

		aa_get_profile(new);

		aa_put_profile(old);

	} else
@@ -1099,7 +1100,7 @@ ssize_t aa_replace_profiles(void *udata, size_t size, bool noreplace) 
		goto fail;

	}



	write_lock(&ns->lock);

	mutex_lock(&ns->lock);

	/* setup parent and ns info */

	list_for_each_entry(ent, &lh, list) {

		struct aa_policy *policy;
@@ -1135,11 +1136,12 @@ ssize_t aa_replace_profiles(void *udata, size_t size, bool noreplace) 
				name = ent->new->base.hname;

				goto fail_lock;

			}

			ent->new->parent = aa_get_profile(p);

		} else if (policy != &ns->base)

			rcu_assign_pointer(ent->new->parent, aa_get_profile(p));

		} else if (policy != &ns->base) {

			/* released on profile replacement or free_profile */

			ent->new->parent = aa_get_profile((struct aa_profile *)

							  policy);

			struct aa_profile *p = (struct aa_profile *) policy;

			rcu_assign_pointer(ent->new->parent, aa_get_profile(p));

		}

	}



	/* do actual replacement */
@@ -1156,13 +1158,16 @@ ssize_t aa_replace_profiles(void *udata, size_t size, bool noreplace) 
		} else if (ent->rename) {

			__replace_profile(ent->rename, ent->new);

		} else if (ent->new->parent) {

			struct aa_profile *parent;

			parent = aa_newest_version(ent->new->parent);

			struct aa_profile *parent, *newest;

			parent = rcu_dereference_protected(ent->new->parent,

						    mutex_is_locked(&ns->lock));

			newest = aa_newest_version(parent);



			/* parent replaced in this atomic set? */

			if (parent != ent->new->parent) {

				aa_get_profile(parent);

				aa_put_profile(ent->new->parent);

				ent->new->parent = parent;

			if (newest != parent) {

				aa_get_profile(newest);

				aa_put_profile(parent);

				rcu_assign_pointer(ent->new->parent, newest);

			}

			__list_add_profile(&parent->base.profiles, ent->new);

		} else
@@ -1170,7 +1175,7 @@ ssize_t aa_replace_profiles(void *udata, size_t size, bool noreplace) 


		aa_load_ent_free(ent);

	}

	write_unlock(&ns->lock);

	mutex_unlock(&ns->lock);



out:

	aa_put_namespace(ns);
@@ -1180,7 +1185,7 @@ out: 
	return size;



fail_lock:

	write_unlock(&ns->lock);

	mutex_unlock(&ns->lock);

fail:

	error = audit_policy(op, GFP_KERNEL, name, info, error);
@@ -1235,12 +1240,12 @@ ssize_t aa_remove_profiles(char *fqname, size_t size) 


	if (!name) {

		/* remove namespace - can only happen if fqname[0] == ':' */

		write_lock(&ns->parent->lock);

		mutex_lock(&ns->parent->lock);

		__remove_namespace(ns);

		write_unlock(&ns->parent->lock);

		mutex_unlock(&ns->parent->lock);

	} else {

		/* remove profile */

		write_lock(&ns->lock);

		mutex_lock(&ns->lock);

		profile = aa_get_profile(__lookup_profile(&ns->base, name));

		if (!profile) {

			error = -ENOENT;
@@ -1249,7 +1254,7 @@ ssize_t aa_remove_profiles(char *fqname, size_t size) 
		}

		name = profile->base.hname;

		__remove_profile(profile);

		write_unlock(&ns->lock);

		mutex_unlock(&ns->lock);

	}



	/* don't fail removal if audit fails */
@@ -1259,7 +1264,7 @@ ssize_t aa_remove_profiles(char *fqname, size_t size) 
	return size;



fail_ns_lock:

	write_unlock(&ns->lock);

	mutex_unlock(&ns->lock);

	aa_put_namespace(ns);



fail: