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lua-lsm: fix unregister and module lifetime handling #16

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57ff4e5
lua-lsm: fix shared dict lifetime on unregister
chenzongyao200127 May 9, 2026
b53cdab
lua-lsm: avoid leaking shared dict refs on userdata failure
chenzongyao200127 May 9, 2026
e5bc8fc
lua-lsm: avoid Lua teardown from task_call_func
chenzongyao200127 May 9, 2026
3b3aa86
lua-lsm: finalize drained modules after lazy unload
chenzongyao200127 May 11, 2026
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68 changes: 55 additions & 13 deletions security/lua/kvcache.c
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Original file line number Diff line number Diff line change
Expand Up @@ -477,6 +477,30 @@ void kvcache_dict_init(struct kvcache_dict *dict)
dict->capacity = CACHE_CAPACITY;
}

static void lua_lsm_shdict_free_rcu(struct rcu_head *head)
{
struct lua_lsm_module_shdict *shdict;

shdict = container_of(head, struct lua_lsm_module_shdict, rcu);
kvcache_dict_free(&shdict->dict);
kfree(shdict);
}

void lua_lsm_shdict_get(struct lua_lsm_module_shdict *shdict)
{
if (shdict)
refcount_acquire(&shdict->refcount);
}

void lua_lsm_shdict_put(struct lua_lsm_module_shdict *shdict)
{
if (!shdict)
return;

if (refcount_release(&shdict->refcount) == 0)
call_rcu(&shdict->rcu, lua_lsm_shdict_free_rcu);
}

/******************************** object cache *******************************/

const int _module_sentinel;
Expand Down Expand Up @@ -595,28 +619,37 @@ int lua_object_newindex(lua_State *L, struct kvcache_dict *dict)

static int shdict_set(lua_State *L)
{
struct kvcache_dict *shdict = toshdict(L, 1);
struct lua_lsm_module_shdict *shdict = toshdict(L, 1);

return kvcache_set(L, shdict, NULL);
if (READ_ONCE(shdict->dead))
return kvcache_result(L, -ESRCH);

return kvcache_set(L, &shdict->dict, NULL);
}

static int shdict_get(lua_State *L)
{
struct kvcache_dict *shdict = toshdict(L, 1);
struct lua_lsm_module_shdict *shdict = toshdict(L, 1);

if (READ_ONCE(shdict->dead))
return kvcache_result(L, -ESRCH);

return kvcache_get(L, shdict, NULL);
return kvcache_get(L, &shdict->dict, NULL);
}

static int shdict_incr(lua_State *L)
{
struct kvcache_dict *shdict = toshdict(L, 1);
struct lua_lsm_module_shdict *shdict = toshdict(L, 1);

if (READ_ONCE(shdict->dead))
return kvcache_result(L, -ESRCH);

return kvcache_incr(L, shdict, NULL);
return kvcache_incr(L, &shdict->dict, NULL);
}

static int shdict_index(lua_State *L)
{
struct kvcache_dict *shdict = toshdict(L, 1);
struct lua_lsm_module_shdict *shdict = toshdict(L, 1);

/* metatable[key] */
if (lua_getmetatable(L, 1) == 0) {
Expand All @@ -628,24 +661,33 @@ static int shdict_index(lua_State *L)
if (!lua_isnoneornil(L, -1))
return 1;

return kvcache_get(L, shdict, NULL);
if (READ_ONCE(shdict->dead))
return kvcache_result(L, -ESRCH);

return kvcache_get(L, &shdict->dict, NULL);
}

static int shdict_tostring(lua_State *L)
{
struct kvcache_dict *shdict = toshdict(L, 1);
struct lua_lsm_module_shdict *shdict = toshdict(L, 1);
unsigned long flags;

read_lock_irqsave(&shdict->lock, flags);
if (READ_ONCE(shdict->dead)) {
lua_pushliteral(L, "shdict (dead)");
return 1;
}

read_lock_irqsave(&shdict->dict.lock, flags);
lua_pushfstring(L, "shdict (%d / %d)",
atomic_read(&shdict->count), shdict->capacity);
read_unlock_irqrestore(&shdict->lock, flags);
atomic_read(&shdict->dict.count),
shdict->dict.capacity);
read_unlock_irqrestore(&shdict->dict.lock, flags);
return 1;
}

static int shdict_gc(lua_State *L)
{
__log_info_ratelimited("shdict already freed by unregister\n");
lua_lsm_shdict_put(toshdict(L, 1));
return 0;
}

Expand Down
9 changes: 7 additions & 2 deletions security/lua/kvcache.h
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
#define CACHE_CAPACITY 1024

struct lua_lsm_module;
struct lua_lsm_module_shdict;

struct kvcache_node {
const char *key;
Expand Down Expand Up @@ -67,11 +68,15 @@ int lua_object_newindex(lua_State *L, struct kvcache_dict *dict);
#define METH_SHARED_DICT "meth_shared_dict"

#define newshdict(L) \
((struct kvcache_dict **)newcptr((L), METH_SHARED_DICT))
((struct lua_lsm_module_shdict **) \
newcptr((L), METH_SHARED_DICT))
#define toshdictp(L, idx) \
((struct kvcache_dict **)luaL_checkudata((L), (idx), METH_SHARED_DICT))
((struct lua_lsm_module_shdict **) \
luaL_checkudata((L), (idx), METH_SHARED_DICT))
#define toshdict(L, idx) (*toshdictp(L, idx))

void lua_lsm_shdict_get(struct lua_lsm_module_shdict *shdict);
void lua_lsm_shdict_put(struct lua_lsm_module_shdict *shdict);
int shdict_init(lua_State *L);

#endif /* ! _SECURITY_LUA_LSM_KVCACHE_H */
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