diff options
Diffstat (limited to 'security/keys')
| -rw-r--r-- | security/keys/Kconfig | 18 | ||||
| -rw-r--r-- | security/keys/internal.h | 6 | ||||
| -rw-r--r-- | security/keys/key.c | 4 | ||||
| -rw-r--r-- | security/keys/keyring.c | 16 | ||||
| -rw-r--r-- | security/keys/proc.c | 4 | ||||
| -rw-r--r-- | security/keys/process_keys.c | 41 | ||||
| -rw-r--r-- | security/keys/request_key.c | 137 | ||||
| -rw-r--r-- | security/keys/request_key_auth.c | 60 |
8 files changed, 180 insertions, 106 deletions
diff --git a/security/keys/Kconfig b/security/keys/Kconfig index ee502e4d390b..dd313438fecf 100644 --- a/security/keys/Kconfig +++ b/security/keys/Kconfig @@ -25,6 +25,24 @@ config KEYS_COMPAT def_bool y depends on COMPAT && KEYS +config KEYS_REQUEST_CACHE + bool "Enable temporary caching of the last request_key() result" + depends on KEYS + help + This option causes the result of the last successful request_key() + call that didn't upcall to the kernel to be cached temporarily in the + task_struct. The cache is cleared by exit and just prior to the + resumption of userspace. + + This allows the key used for multiple step processes where each step + wants to request a key that is likely the same as the one requested + by the last step to save on the searching. + + An example of such a process is a pathwalk through a network + filesystem in which each method needs to request an authentication + key. Pathwalk will call multiple methods for each dentry traversed + (permission, d_revalidate, lookup, getxattr, getacl, ...). + config PERSISTENT_KEYRINGS bool "Enable register of persistent per-UID keyrings" depends on KEYS diff --git a/security/keys/internal.h b/security/keys/internal.h index 0f48b53754b3..663f291e30d4 100644 --- a/security/keys/internal.h +++ b/security/keys/internal.h @@ -135,11 +135,11 @@ struct keyring_search_context { extern bool key_default_cmp(const struct key *key, const struct key_match_data *match_data); -extern key_ref_t keyring_search_aux(key_ref_t keyring_ref, +extern key_ref_t keyring_search_rcu(key_ref_t keyring_ref, struct keyring_search_context *ctx); -extern key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx); -extern key_ref_t search_process_keyrings(struct keyring_search_context *ctx); +extern key_ref_t search_cred_keyrings_rcu(struct keyring_search_context *ctx); +extern key_ref_t search_process_keyrings_rcu(struct keyring_search_context *ctx); extern struct key *find_keyring_by_name(const char *name, bool uid_keyring); diff --git a/security/keys/key.c b/security/keys/key.c index d3c17d76ea76..85dddc0190a7 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -455,7 +455,7 @@ static int __key_instantiate_and_link(struct key *key, /* disable the authorisation key */ if (authkey) - key_revoke(authkey); + key_invalidate(authkey); if (prep->expiry != TIME64_MAX) { key->expiry = prep->expiry; @@ -612,7 +612,7 @@ int key_reject_and_link(struct key *key, /* disable the authorisation key */ if (authkey) - key_revoke(authkey); + key_invalidate(authkey); } mutex_unlock(&key_construction_mutex); diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 204b5a4d180e..e4de4070c754 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -831,7 +831,7 @@ found: } /** - * keyring_search_aux - Search a keyring tree for a key matching some criteria + * keyring_search_rcu - Search a keyring tree for a matching key under RCU * @keyring_ref: A pointer to the keyring with possession indicator. * @ctx: The keyring search context. * @@ -843,7 +843,9 @@ found: * addition, the LSM gets to forbid keyring searches and key matches. * * The search is performed as a breadth-then-depth search up to the prescribed - * limit (KEYRING_SEARCH_MAX_DEPTH). + * limit (KEYRING_SEARCH_MAX_DEPTH). The caller must hold the RCU read lock to + * prevent keyrings from being destroyed or rearranged whilst they are being + * searched. * * Keys are matched to the type provided and are then filtered by the match * function, which is given the description to use in any way it sees fit. The @@ -862,7 +864,7 @@ found: * In the case of a successful return, the possession attribute from * @keyring_ref is propagated to the returned key reference. */ -key_ref_t keyring_search_aux(key_ref_t keyring_ref, +key_ref_t keyring_search_rcu(key_ref_t keyring_ref, struct keyring_search_context *ctx) { struct key *keyring; @@ -884,11 +886,9 @@ key_ref_t keyring_search_aux(key_ref_t keyring_ref, return ERR_PTR(err); } - rcu_read_lock(); ctx->now = ktime_get_real_seconds(); if (search_nested_keyrings(keyring, ctx)) __key_get(key_ref_to_ptr(ctx->result)); - rcu_read_unlock(); return ctx->result; } @@ -898,7 +898,7 @@ key_ref_t keyring_search_aux(key_ref_t keyring_ref, * @type: The type of keyring we want to find. * @description: The name of the keyring we want to find. * - * As keyring_search_aux() above, but using the current task's credentials and + * As keyring_search_rcu() above, but using the current task's credentials and * type's default matching function and preferred search method. */ key_ref_t keyring_search(key_ref_t keyring, @@ -924,7 +924,9 @@ key_ref_t keyring_search(key_ref_t keyring, return ERR_PTR(ret); } - key = keyring_search_aux(keyring, &ctx); + rcu_read_lock(); + key = keyring_search_rcu(keyring, &ctx); + rcu_read_unlock(); if (type->match_free) type->match_free(&ctx.match_data); diff --git a/security/keys/proc.c b/security/keys/proc.c index 4e3266a2529e..7f15550c10f5 100644 --- a/security/keys/proc.c +++ b/security/keys/proc.c @@ -175,7 +175,9 @@ static int proc_keys_show(struct seq_file *m, void *v) * skip if the key does not indicate the possessor can view it */ if (key->perm & KEY_POS_VIEW) { - skey_ref = search_my_process_keyrings(&ctx); + rcu_read_lock(); + skey_ref = search_cred_keyrings_rcu(&ctx); + rcu_read_unlock(); if (!IS_ERR(skey_ref)) { key_ref_put(skey_ref); key_ref = make_key_ref(key, 1); diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c index a40b33614208..b99ad2c5342f 100644 --- a/security/keys/process_keys.c +++ b/security/keys/process_keys.c @@ -314,7 +314,8 @@ void key_fsgid_changed(struct cred *new_cred) /* * Search the process keyrings attached to the supplied cred for the first - * matching key. + * matching key under RCU conditions (the caller must be holding the RCU read + * lock). * * The search criteria are the type and the match function. The description is * given to the match function as a parameter, but doesn't otherwise influence @@ -333,7 +334,7 @@ void key_fsgid_changed(struct cred *new_cred) * In the case of a successful return, the possession attribute is set on the * returned key reference. */ -key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) +key_ref_t search_cred_keyrings_rcu(struct keyring_search_context *ctx) { key_ref_t key_ref, ret, err; const struct cred *cred = ctx->cred; @@ -351,7 +352,7 @@ key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) /* search the thread keyring first */ if (cred->thread_keyring) { - key_ref = keyring_search_aux( + key_ref = keyring_search_rcu( make_key_ref(cred->thread_keyring, 1), ctx); if (!IS_ERR(key_ref)) goto found; @@ -369,7 +370,7 @@ key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) /* search the process keyring second */ if (cred->process_keyring) { - key_ref = keyring_search_aux( + key_ref = keyring_search_rcu( make_key_ref(cred->process_keyring, 1), ctx); if (!IS_ERR(key_ref)) goto found; @@ -390,7 +391,7 @@ key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) /* search the session keyring */ if (cred->session_keyring) { - key_ref = keyring_search_aux( + key_ref = keyring_search_rcu( make_key_ref(cred->session_keyring, 1), ctx); if (!IS_ERR(key_ref)) @@ -411,7 +412,7 @@ key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) } /* or search the user-session keyring */ else if (READ_ONCE(cred->user->session_keyring)) { - key_ref = keyring_search_aux( + key_ref = keyring_search_rcu( make_key_ref(READ_ONCE(cred->user->session_keyring), 1), ctx); if (!IS_ERR(key_ref)) @@ -444,16 +445,16 @@ found: * the keys attached to the assumed authorisation key using its credentials if * one is available. * - * Return same as search_my_process_keyrings(). + * The caller must be holding the RCU read lock. + * + * Return same as search_cred_keyrings_rcu(). */ -key_ref_t search_process_keyrings(struct keyring_search_context *ctx) +key_ref_t search_process_keyrings_rcu(struct keyring_search_context *ctx) { struct request_key_auth *rka; key_ref_t key_ref, ret = ERR_PTR(-EACCES), err; - might_sleep(); - - key_ref = search_my_process_keyrings(ctx); + key_ref = search_cred_keyrings_rcu(ctx); if (!IS_ERR(key_ref)) goto found; err = key_ref; @@ -468,24 +469,17 @@ key_ref_t search_process_keyrings(struct keyring_search_context *ctx) ) { const struct cred *cred = ctx->cred; - /* defend against the auth key being revoked */ - down_read(&cred->request_key_auth->sem); - - if (key_validate(ctx->cred->request_key_auth) == 0) { + if (key_validate(cred->request_key_auth) == 0) { rka = ctx->cred->request_key_auth->payload.data[0]; + //// was search_process_keyrings() [ie. recursive] ctx->cred = rka->cred; - key_ref = search_process_keyrings(ctx); + key_ref = search_cred_keyrings_rcu(ctx); ctx->cred = cred; - up_read(&cred->request_key_auth->sem); - if (!IS_ERR(key_ref)) goto found; - ret = key_ref; - } else { - up_read(&cred->request_key_auth->sem); } } @@ -500,7 +494,6 @@ key_ref_t search_process_keyrings(struct keyring_search_context *ctx) found: return key_ref; } - /* * See if the key we're looking at is the target key. */ @@ -687,7 +680,9 @@ try_again: ctx.index_key = key->index_key; ctx.match_data.raw_data = key; kdebug("check possessed"); - skey_ref = search_process_keyrings(&ctx); + rcu_read_lock(); + skey_ref = search_process_keyrings_rcu(&ctx); + rcu_read_unlock(); kdebug("possessed=%p", skey_ref); if (!IS_ERR(skey_ref)) { diff --git a/security/keys/request_key.c b/security/keys/request_key.c index fcef7e26b94b..f2b4da143963 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -18,6 +18,31 @@ #define key_negative_timeout 60 /* default timeout on a negative key's existence */ +static struct key *check_cached_key(struct keyring_search_context *ctx) +{ +#ifdef CONFIG_KEYS_REQUEST_CACHE + struct key *key = current->cached_requested_key; + + if (key && + ctx->match_data.cmp(key, &ctx->match_data) && + !(key->flags & ((1 << KEY_FLAG_INVALIDATED) | + (1 << KEY_FLAG_REVOKED)))) + return key_get(key); +#endif + return NULL; +} + +static void cache_requested_key(struct key *key) +{ +#ifdef CONFIG_KEYS_REQUEST_CACHE + struct task_struct *t = current; + + key_put(t->cached_requested_key); + t->cached_requested_key = key_get(key); + set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); +#endif +} + /** * complete_request_key - Complete the construction of a key. * @authkey: The authorisation key. @@ -218,7 +243,7 @@ static int construct_key(struct key *key, const void *callout_info, /* check that the actor called complete_request_key() prior to * returning an error */ WARN_ON(ret < 0 && - !test_bit(KEY_FLAG_REVOKED, &authkey->flags)); + !test_bit(KEY_FLAG_INVALIDATED, &authkey->flags)); key_put(authkey); kleave(" = %d", ret); @@ -381,7 +406,9 @@ static int construct_alloc_key(struct keyring_search_context *ctx, * waited for locks */ mutex_lock(&key_construction_mutex); - key_ref = search_process_keyrings(ctx); + rcu_read_lock(); + key_ref = search_process_keyrings_rcu(ctx); + rcu_read_unlock(); if (!IS_ERR(key_ref)) goto key_already_present; @@ -556,10 +583,26 @@ struct key *request_key_and_link(struct key_type *type, } } + key = check_cached_key(&ctx); + if (key) + return key; + /* search all the process keyrings for a key */ - key_ref = search_process_keyrings(&ctx); + rcu_read_lock(); + key_ref = search_process_keyrings_rcu(&ctx); + rcu_read_unlock(); if (!IS_ERR(key_ref)) { + if (dest_keyring) { + ret = key_task_permission(key_ref, current_cred(), + KEY_NEED_LINK); + if (ret < 0) { + key_ref_put(key_ref); + key = ERR_PTR(ret); + goto error_free; + } + } + key = key_ref_to_ptr(key_ref); if (dest_keyring) { ret = key_link(dest_keyring, key); @@ -569,6 +612,9 @@ struct key *request_key_and_link(struct key_type *type, goto error_free; } } + + /* Only cache the key on immediate success */ + cache_requested_key(key); } else if (PTR_ERR(key_ref) != -EAGAIN) { key = ERR_CAST(key_ref); } else { @@ -689,52 +735,51 @@ struct key *request_key_with_auxdata(struct key_type *type, } EXPORT_SYMBOL(request_key_with_auxdata); -/* - * request_key_async - Request a key (allow async construction) - * @type: Type of key. - * @description: The searchable description of the key. - * @callout_info: The data to pass to the instantiation upcall (or NULL). - * @callout_len: The length of callout_info. +/** + * request_key_rcu - Request key from RCU-read-locked context + * @type: The type of key we want. + * @description: The name of the key we want. * - * As for request_key_and_link() except that it does not add the returned key - * to a keyring if found, new keys are always allocated in the user's quota and - * no auxiliary data can be passed. + * Request a key from a context that we may not sleep in (such as RCU-mode + * pathwalk). Keys under construction are ignored. * - * The caller should call wait_for_key_construction() to wait for the - * completion of the returned key if it is still undergoing construction. + * Return a pointer to the found key if successful, -ENOKEY if we couldn't find + * a key or some other error if the key found was unsuitable or inaccessible. */ -struct key *request_key_async(struct key_type *type, - const char *description, - const void *callout_info, - size_t callout_len) +struct key *request_key_rcu(struct key_type *type, const char *description) { - return request_key_and_link(type, description, callout_info, - callout_len, NULL, NULL, - KEY_ALLOC_IN_QUOTA); -} -EXPORT_SYMBOL(request_key_async); + struct keyring_search_context ctx = { + .index_key.type = type, + .index_key.description = description, + .index_key.desc_len = strlen(description), + .cred = current_cred(), + .match_data.cmp = key_default_cmp, + .match_data.raw_data = description, + .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, + .flags = (KEYRING_SEARCH_DO_STATE_CHECK | + KEYRING_SEARCH_SKIP_EXPIRED), + }; + struct key *key; + key_ref_t key_ref; -/* - * request a key with auxiliary data for the upcaller (allow async construction) - * @type: Type of key. - * @description: The searchable description of the key. - * @callout_info: The data to pass to the instantiation upcall (or NULL). - * @callout_len: The length of callout_info. - * @aux: Auxiliary data for the upcall. - * - * As for request_key_and_link() except that it does not add the returned key - * to a keyring if found and new keys are always allocated in the user's quota. - * - * The caller should call wait_for_key_construction() to wait for the - * completion of the returned key if it is still undergoing construction. - */ -struct key *request_key_async_with_auxdata(struct key_type *type, - const char *description, - const void *callout_info, - size_t callout_len, - void *aux) -{ - return request_key_and_link(type, description, callout_info, - callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA); + kenter("%s,%s", type->name, description); + + key = check_cached_key(&ctx); + if (key) + return key; + + /* search all the process keyrings for a key */ + key_ref = search_process_keyrings_rcu(&ctx); + if (IS_ERR(key_ref)) { + key = ERR_CAST(key_ref); + if (PTR_ERR(key_ref) == -EAGAIN) + key = ERR_PTR(-ENOKEY); + } else { + key = key_ref_to_ptr(key_ref); + cache_requested_key(key); + } + + kleave(" = %p", key); + return key; } -EXPORT_SYMBOL(request_key_async_with_auxdata); +EXPORT_SYMBOL(request_key_rcu); diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c index 3d8616f981b2..5456c0c72857 100644 --- a/security/keys/request_key_auth.c +++ b/security/keys/request_key_auth.c @@ -54,7 +54,7 @@ static void request_key_auth_free_preparse(struct key_preparsed_payload *prep) static int request_key_auth_instantiate(struct key *key, struct key_preparsed_payload *prep) { - key->payload.data[0] = (struct request_key_auth *)prep->data; + rcu_assign_keypointer(key, (struct request_key_auth *)prep->data); return 0; } @@ -64,7 +64,7 @@ static int request_key_auth_instantiate(struct key *key, static void request_key_auth_describe(const struct key *key, struct seq_file *m) { - struct request_key_auth *rka = get_request_key_auth(key); + struct request_key_auth *rka = dereference_key_rcu(key); seq_puts(m, "key:"); seq_puts(m, key->description); @@ -79,7 +79,7 @@ static void request_key_auth_describe(const struct key *key, static long request_key_auth_read(const struct key *key, char __user *buffer, size_t buflen) { - struct request_key_auth *rka = get_request_key_auth(key); + struct request_key_auth *rka = dereference_key_locked(key); size_t datalen; long ret; @@ -98,23 +98,6 @@ static long request_key_auth_read(const struct key *key, return ret; } -/* - * Handle revocation of an authorisation token key. - * - * Called with the key sem write-locked. - */ -static void request_key_auth_revoke(struct key *key) -{ - struct request_key_auth *rka = get_request_key_auth(key); - - kenter("{%d}", key->serial); - - if (rka->cred) { - put_cred(rka->cred); - rka->cred = NULL; - } -} - static void free_request_key_auth(struct request_key_auth *rka) { if (!rka) @@ -128,15 +111,42 @@ static void free_request_key_auth(struct request_key_auth *rka) } /* + * Dispose of the request_key_auth record under RCU conditions + */ +static void request_key_auth_rcu_disposal(struct rcu_head *rcu) +{ + struct request_key_auth *rka = + container_of(rcu, struct request_key_auth, rcu); + + free_request_key_auth(rka); +} + +/* + * Handle revocation of an authorisation token key. + * + * Called with the key sem write-locked. + */ +static void request_key_auth_revoke(struct key *key) +{ + struct request_key_auth *rka = dereference_key_locked(key); + + kenter("{%d}", key->serial); + rcu_assign_keypointer(key, NULL); + call_rcu(&rka->rcu, request_key_auth_rcu_disposal); +} + +/* * Destroy an instantiation authorisation token key. */ static void request_key_auth_destroy(struct key *key) { - struct request_key_auth *rka = get_request_key_auth(key); + struct request_key_auth *rka = rcu_access_pointer(key->payload.rcu_data0); kenter("{%d}", key->serial); - - free_request_key_auth(rka); + if (rka) { + rcu_assign_keypointer(key, NULL); + call_rcu(&rka->rcu, request_key_auth_rcu_disposal); + } } /* @@ -245,7 +255,9 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id) ctx.index_key.desc_len = sprintf(description, "%x", target_id); - authkey_ref = search_process_keyrings(&ctx); + rcu_read_lock(); + authkey_ref = search_process_keyrings_rcu(&ctx); + rcu_read_unlock(); if (IS_ERR(authkey_ref)) { authkey = ERR_CAST(authkey_ref); |