diff --git a/Documentation/keys.txt b/Documentation/keys.txt
index 703020012708506fb9f83ab2e206af3db781c3af..3bbe157b45e470ca656c72e47e523138c9be6fe8 100644
--- a/Documentation/keys.txt
+++ b/Documentation/keys.txt
@@ -964,6 +964,16 @@ The structure has a number of fields, some of which are mandatory:
It is not safe to sleep in this method; the caller may hold spinlocks.
+ (*) void (*revoke)(struct key *key);
+
+ This method is optional. It is called to discard part of the payload
+ data upon a key being revoked. The caller will have the key semaphore
+ write-locked.
+
+ It is safe to sleep in this method, though care should be taken to avoid
+ a deadlock against the key semaphore.
+
+
(*) void (*destroy)(struct key *key);
This method is optional. It is called to discard the payload data on a key
diff --git a/include/linux/key.h b/include/linux/key.h
index 8c275d12ef637ac83ba61d1e1fcfdfc95fc36bb0..e81ebf910d0bc3d9b1b38732f59947f1270ba99e 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -205,6 +205,11 @@ struct key_type {
/* match a key against a description */
int (*match)(const struct key *key, const void *desc);
+ /* clear some of the data from a key on revokation (optional)
+ * - the key's semaphore will be write-locked by the caller
+ */
+ void (*revoke)(struct key *key);
+
/* clear the data from a key (optional) */
void (*destroy)(struct key *key);
diff --git a/security/keys/key.c b/security/keys/key.c
index 14a15abb77355700c05b2f938d485d6182d27027..51f8515573894f93103c802cad0173e7f53e23b2 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -907,6 +907,10 @@ void key_revoke(struct key *key)
* it */
down_write(&key->sem);
set_bit(KEY_FLAG_REVOKED, &key->flags);
+
+ if (key->type->revoke)
+ key->type->revoke(key);
+
up_write(&key->sem);
} /* end key_revoke() */
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index a50a91332fe1be47c68fe82b0c6dfe63c4f53257..4d9825f9962cb027e5f610380177d2722d60aca0 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -391,6 +391,8 @@ key_ref_t search_process_keyrings(struct key_type *type,
struct request_key_auth *rka;
key_ref_t key_ref, ret, err;
+ might_sleep();
+
/* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
* searchable, but we failed to find a key or we found a negative key;
* otherwise we want to return a sample error (probably -EACCES) if
@@ -496,27 +498,35 @@ key_ref_t search_process_keyrings(struct key_type *type,
*/
if (context->request_key_auth &&
context == current &&
- type != &key_type_request_key_auth &&
- key_validate(context->request_key_auth) == 0
+ type != &key_type_request_key_auth
) {
- rka = context->request_key_auth->payload.data;
+ /* defend against the auth key being revoked */
+ down_read(&context->request_key_auth->sem);
- key_ref = search_process_keyrings(type, description, match,
- rka->context);
+ if (key_validate(context->request_key_auth) == 0) {
+ rka = context->request_key_auth->payload.data;
- if (!IS_ERR(key_ref))
- goto found;
+ key_ref = search_process_keyrings(type, description,
+ match, rka->context);
- switch (PTR_ERR(key_ref)) {
- case -EAGAIN: /* no key */
- if (ret)
+ up_read(&context->request_key_auth->sem);
+
+ if (!IS_ERR(key_ref))
+ goto found;
+
+ switch (PTR_ERR(key_ref)) {
+ case -EAGAIN: /* no key */
+ if (ret)
+ break;
+ case -ENOKEY: /* negative key */
+ ret = key_ref;
break;
- case -ENOKEY: /* negative key */
- ret = key_ref;
- break;
- default:
- err = key_ref;
- break;
+ default:
+ err = key_ref;
+ break;
+ }
+ } else {
+ up_read(&context->request_key_auth->sem);
}
}
diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index 0ecc2e8d2bd0f6ca82da683e895a869f61ad3190..cb9817ced3fd8ce3419bf52d449f6b191d8bbed4 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -20,6 +20,7 @@
static int request_key_auth_instantiate(struct key *, const void *, size_t);
static void request_key_auth_describe(const struct key *, struct seq_file *);
+static void request_key_auth_revoke(struct key *);
static void request_key_auth_destroy(struct key *);
static long request_key_auth_read(const struct key *, char __user *, size_t);
@@ -31,6 +32,7 @@ struct key_type key_type_request_key_auth = {
.def_datalen = sizeof(struct request_key_auth),
.instantiate = request_key_auth_instantiate,
.describe = request_key_auth_describe,
+ .revoke = request_key_auth_revoke,
.destroy = request_key_auth_destroy,
.read = request_key_auth_read,
};
@@ -91,6 +93,24 @@ static long request_key_auth_read(const struct key *key,
} /* end request_key_auth_read() */
+/*****************************************************************************/
+/*
+ * 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 = key->payload.data;
+
+ kenter("{%d}", key->serial);
+
+ if (rka->context) {
+ put_task_struct(rka->context);
+ rka->context = NULL;
+ }
+
+} /* end request_key_auth_revoke() */
+
/*****************************************************************************/
/*
* destroy an instantiation authorisation token key
@@ -101,6 +121,11 @@ static void request_key_auth_destroy(struct key *key)
kenter("{%d}", key->serial);
+ if (rka->context) {
+ put_task_struct(rka->context);
+ rka->context = NULL;
+ }
+
key_put(rka->target_key);
kfree(rka);
@@ -131,14 +156,26 @@ struct key *request_key_auth_new(struct key *target, const char *callout_info)
* another process */
if (current->request_key_auth) {
/* it is - use that instantiation context here too */
+ down_read(¤t->request_key_auth->sem);
+
+ /* if the auth key has been revoked, then the key we're
+ * servicing is already instantiated */
+ if (test_bit(KEY_FLAG_REVOKED,
+ ¤t->request_key_auth->flags))
+ goto auth_key_revoked;
+
irka = current->request_key_auth->payload.data;
rka->context = irka->context;
rka->pid = irka->pid;
+ get_task_struct(rka->context);
+
+ up_read(¤t->request_key_auth->sem);
}
else {
/* it isn't - use this process as the context */
rka->context = current;
rka->pid = current->pid;
+ get_task_struct(rka->context);
}
rka->target_key = key_get(target);
@@ -161,9 +198,15 @@ struct key *request_key_auth_new(struct key *target, const char *callout_info)
if (ret < 0)
goto error_inst;
- kleave(" = {%d})", authkey->serial);
+ kleave(" = {%d}", authkey->serial);
return authkey;
+auth_key_revoked:
+ up_read(¤t->request_key_auth->sem);
+ kfree(rka);
+ kleave("= -EKEYREVOKED");
+ return ERR_PTR(-EKEYREVOKED);
+
error_inst:
key_revoke(authkey);
key_put(authkey);