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apparmor: convert profile lists to RCU based locking

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Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
John Johansen 2013-07-10 21:06:43 -07:00
parent dd51c84857
commit 01e2b670aa
4 changed files with 167 additions and 111 deletions
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14
security/apparmor/domain.c
View File

@ -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";

6
security/apparmor/include/apparmor.h
View File

@ -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

45
security/apparmor/include/policy.h
View File

@ -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)

213
security/apparmor/policy.c
View File

@ -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) {
/* add parent ref */
new_ns->parent = aa_get_namespace(root);
list_add(&new_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);
}
ns = alloc_namespace(root->base.hname, name);
if (!ns)
goto out;
/* add parent ref */
ns->parent = aa_get_namespace(root);
list_add_rcu(&ns->base.list, &root->sub_ns);
/* add list ref */
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);
}
@ -466,10 +452,8 @@ 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 */
aa_put_profile(profile);
list_del_rcu(&profile->base.list);
aa_put_profile(profile);
}
static void __profile_list_release(struct list_head *head);
@ -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: