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Fix hash_lock / keystore.sk_dk_lock lock inversion #7115

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Feb 4, 2018
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Fix hash_lock / keystore.sk_dk_lock lock inversion #7115

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87 changes: 39 additions & 48 deletions module/zfs/dsl_crypt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -655,55 +655,56 @@ spa_keystore_dsl_key_hold_dd(spa_t *spa, dsl_dir_t *dd, void *tag,
{
int ret;
avl_index_t where;
dsl_crypto_key_t *dck = NULL;
dsl_crypto_key_t *dck_io = NULL, *dck_ks = NULL;
dsl_wrapping_key_t *wkey = NULL;
uint64_t dckobj = dd->dd_crypto_obj;

rw_enter(&spa->spa_keystore.sk_dk_lock, RW_WRITER);

/* lookup the key in the tree of currently loaded keys */
ret = spa_keystore_dsl_key_hold_impl(spa, dckobj, tag, &dck);
if (!ret) {
rw_exit(&spa->spa_keystore.sk_dk_lock);
*dck_out = dck;
/* Lookup the key in the tree of currently loaded keys */
rw_enter(&spa->spa_keystore.sk_dk_lock, RW_READER);
ret = spa_keystore_dsl_key_hold_impl(spa, dckobj, tag, &dck_ks);
rw_exit(&spa->spa_keystore.sk_dk_lock);
if (ret == 0) {
*dck_out = dck_ks;
return (0);
}

/* lookup the wrapping key from the keystore */
/* Lookup the wrapping key from the keystore */
ret = spa_keystore_wkey_hold_dd(spa, dd, FTAG, &wkey);
if (ret != 0) {
ret = SET_ERROR(EACCES);
goto error_unlock;
*dck_out = NULL;
return (SET_ERROR(EACCES));
}

/* read the key from disk */
/* Read the key from disk */
ret = dsl_crypto_key_open(spa->spa_meta_objset, wkey, dckobj,
tag, &dck);
if (ret != 0)
goto error_unlock;
tag, &dck_io);
if (ret != 0) {
dsl_wrapping_key_rele(wkey, FTAG);
*dck_out = NULL;
return (ret);
}

/*
* add the key to the keystore (this should always succeed
* since we made sure it didn't exist before)
* Add the key to the keystore. It may already exist if it was
* added while performing the read from disk. In this case discard
* it and return the key from the keystore.
*/
avl_find(&spa->spa_keystore.sk_dsl_keys, dck, &where);
avl_insert(&spa->spa_keystore.sk_dsl_keys, dck, where);
rw_enter(&spa->spa_keystore.sk_dk_lock, RW_WRITER);
ret = spa_keystore_dsl_key_hold_impl(spa, dckobj, tag, &dck_ks);
if (ret != 0) {
avl_find(&spa->spa_keystore.sk_dsl_keys, dck_io, &where);
avl_insert(&spa->spa_keystore.sk_dsl_keys, dck_io, where);
*dck_out = dck_io;
} else {
dsl_crypto_key_free(dck_io);
*dck_out = dck_ks;
}

/* release the wrapping key (the dsl key now has a reference to it) */
/* Release the wrapping key (the dsl key now has a reference to it) */
dsl_wrapping_key_rele(wkey, FTAG);

rw_exit(&spa->spa_keystore.sk_dk_lock);

*dck_out = dck;
return (0);

error_unlock:
rw_exit(&spa->spa_keystore.sk_dk_lock);
if (wkey != NULL)
dsl_wrapping_key_rele(wkey, FTAG);

*dck_out = NULL;
return (ret);
}

void
Expand Down Expand Up @@ -934,20 +935,19 @@ spa_keystore_create_mapping_impl(spa_t *spa, uint64_t dsobj,
{
int ret;
avl_index_t where;
dsl_key_mapping_t *km = NULL, *found_km;
dsl_key_mapping_t *km, *found_km;
boolean_t should_free = B_FALSE;

/* allocate the mapping */
km = kmem_alloc(sizeof (dsl_key_mapping_t), KM_SLEEP);
if (!km)
return (SET_ERROR(ENOMEM));

/* initialize the mapping */
/* Allocate and initialize the mapping */
km = kmem_zalloc(sizeof (dsl_key_mapping_t), KM_SLEEP);
refcount_create(&km->km_refcnt);

ret = spa_keystore_dsl_key_hold_dd(spa, dd, km, &km->km_key);
if (ret != 0)
goto error;
if (ret != 0) {
refcount_destroy(&km->km_refcnt);
kmem_free(km, sizeof (dsl_key_mapping_t));
return (ret);
}

km->km_dsobj = dsobj;

Expand Down Expand Up @@ -979,15 +979,6 @@ spa_keystore_create_mapping_impl(spa_t *spa, uint64_t dsobj,
}

return (0);

error:
if (km->km_key)
spa_keystore_dsl_key_rele(spa, km->km_key, km);

refcount_destroy(&km->km_refcnt);
kmem_free(km, sizeof (dsl_key_mapping_t));

return (ret);
}

int
Expand Down