keys: allow the callout data to be passed as a blob rather than a string

Allow the callout data to be passed as a blob rather than a string for
internal kernel services that call any request_key_*() interface other than
request_key().  request_key() itself still takes a NUL-terminated string.

The functions that change are:

	request_key_with_auxdata()
	request_key_async()
	request_key_async_with_auxdata()

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Paul Moore <paul.moore@hp.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Cc: Kevin Coffman <kwc@citi.umich.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

7 files changed, 70 insertions, 41 deletions

diff --git a/Documentation/keys-request-key.txt b/Documentation/keys-request-key.txt
index 266955d23ee6..09b55e461740 100644
--- a/Documentation/keys-request-key.txt
+++ b/Documentation/keys-request-key.txt
@@ -11,26 +11,29 @@ request_key*():
 
         struct key *request_key(const struct key_type *type,
                                 const char *description,
-                                const char *callout_string);
+                                const char *callout_info);
 
 or:
 
         struct key *request_key_with_auxdata(const struct key_type *type,
                                              const char *description,
-                                             const char *callout_string,
+                                             const char *callout_info,
+                                             size_t callout_len,
                                              void *aux);
 
 or:
 
         struct key *request_key_async(const struct key_type *type,
                                       const char *description,
-                                      const char *callout_string);
+                                      const char *callout_info,
+                                      size_t callout_len);
 
 or:
 
         struct key *request_key_async_with_auxdata(const struct key_type *type,
                                                    const char *description,
-                                                   const char *callout_string,
+                                                   const char *callout_info,
+                                                   size_t callout_len,
                                                    void *aux);
 
 Or by userspace invoking the request_key system call:
diff --git a/Documentation/keys.txt b/Documentation/keys.txt
index 51652d39e61c..b82d38de8b89 100644
--- a/Documentation/keys.txt
+++ b/Documentation/keys.txt
@@ -771,7 +771,7 @@ payload contents" for more information.
 
         struct key *request_key(const struct key_type *type,
                                 const char *description,
-                                const char *callout_string);
+                                const char *callout_info);
 
     This is used to request a key or keyring with a description that matches
     the description specified according to the key type's match function. This
@@ -793,24 +793,28 @@ payload contents" for more information.
 
         struct key *request_key_with_auxdata(const struct key_type *type,
                                              const char *description,
-                                             const char *callout_string,
+                                             const void *callout_info,
+                                             size_t callout_len,
                                              void *aux);
 
     This is identical to request_key(), except that the auxiliary data is
-    passed to the key_type->request_key() op if it exists.
+    passed to the key_type->request_key() op if it exists, and the callout_info
+    is a blob of length callout_len, if given (the length may be 0).
 
 
 (*) A key can be requested asynchronously by calling one of:
 
         struct key *request_key_async(const struct key_type *type,
                                       const char *description,
-                                      const char *callout_string);
+                                      const void *callout_info,
+                                      size_t callout_len);
 
     or:
 
         struct key *request_key_async_with_auxdata(const struct key_type *type,
                                                    const char *description,
-                                                   const char *callout_string,
+                                                   const char *callout_info,
+                                                   size_t callout_len,
                                                    void *aux);
 
     which are asynchronous equivalents of request_key() and
diff --git a/include/linux/key.h b/include/linux/key.h
index a70b8a8f2005..163f864b6bd4 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -208,16 +208,19 @@ extern struct key *request_key(struct key_type *type,
 
 extern struct key *request_key_with_auxdata(struct key_type *type,
                                             const char *description,
-                                            const char *callout_info,
+                                            const void *callout_info,
+                                            size_t callout_len,
                                             void *aux);
 
 extern struct key *request_key_async(struct key_type *type,
                                      const char *description,
-                                     const char *callout_info);
+                                     const void *callout_info,
+                                     size_t callout_len);
 
 extern struct key *request_key_async_with_auxdata(struct key_type *type,
                                                   const char *description,
-                                                  const char *callout_info,
+                                                  const void *callout_info,
+                                                  size_t callout_len,
                                                   void *aux);
 
 extern int wait_for_key_construction(struct key *key, bool intr);
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 7d894ef70370..3cc04c2afe1c 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -109,7 +109,8 @@ extern int install_process_keyring(struct task_struct *tsk);
 
 extern struct key *request_key_and_link(struct key_type *type,
                                         const char *description,
-                                        const char *callout_info,
+                                        const void *callout_info,
+                                        size_t callout_len,
                                         void *aux,
                                         struct key *dest_keyring,
                                         unsigned long flags);
@@ -120,13 +121,15 @@ extern struct key *request_key_and_link(struct key_type *type,
 struct request_key_auth {
         struct key              *target_key;
         struct task_struct      *context;
-        char                    *callout_info;
+        void                    *callout_info;
+        size_t                  callout_len;
         pid_t                   pid;
 };
 
 extern struct key_type key_type_request_key_auth;
 extern struct key *request_key_auth_new(struct key *target,
-                                        const char *callout_info);
+                                        const void *callout_info,
+                                        size_t callout_len);
 
 extern struct key *key_get_instantiation_authkey(key_serial_t target_id);
 
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 8ec84326a983..1698bf90ee84 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -152,6 +152,7 @@ asmlinkage long sys_request_key(const char __user *_type,
         struct key_type *ktype;
         struct key *key;
         key_ref_t dest_ref;
+        size_t callout_len;
         char type[32], *description, *callout_info;
         long ret;
 
@@ -169,12 +170,14 @@ asmlinkage long sys_request_key(const char __user *_type,
 
         /* pull the callout info into kernel space */
         callout_info = NULL;
+        callout_len = 0;
         if (_callout_info) {
                 callout_info = strndup_user(_callout_info, PAGE_SIZE);
                 if (IS_ERR(callout_info)) {
                         ret = PTR_ERR(callout_info);
                         goto error2;
                 }
+                callout_len = strlen(callout_info);
         }
 
         /* get the destination keyring if specified */
@@ -195,8 +198,8 @@ asmlinkage long sys_request_key(const char __user *_type,
         }
 
         /* do the search */
-        key = request_key_and_link(ktype, description, callout_info, NULL,
-                                   key_ref_to_ptr(dest_ref),
+        key = request_key_and_link(ktype, description, callout_info,
+                                   callout_len, NULL, key_ref_to_ptr(dest_ref),
                                    KEY_ALLOC_IN_QUOTA);
         if (IS_ERR(key)) {
                 ret = PTR_ERR(key);
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 5ecc5057fb54..a3f94c60692d 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -161,21 +161,22 @@ error_alloc:
  * call out to userspace for key construction
  * - we ignore program failure and go on key status instead
  */
-static int construct_key(struct key *key, const char *callout_info, void *aux)
+static int construct_key(struct key *key, const void *callout_info,
+                         size_t callout_len, void *aux)
 {
         struct key_construction *cons;
         request_key_actor_t actor;
         struct key *authkey;
         int ret;
 
-        kenter("%d,%s,%p", key->serial, callout_info, aux);
+        kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
 
         cons = kmalloc(sizeof(*cons), GFP_KERNEL);
         if (!cons)
                 return -ENOMEM;
 
         /* allocate an authorisation key */
-        authkey = request_key_auth_new(key, callout_info);
+        authkey = request_key_auth_new(key, callout_info, callout_len);
         if (IS_ERR(authkey)) {
                 kfree(cons);
                 ret = PTR_ERR(authkey);
@@ -331,6 +332,7 @@ alloc_failed:
 static struct key *construct_key_and_link(struct key_type *type,
                                           const char *description,
                                           const char *callout_info,
+                                          size_t callout_len,
                                           void *aux,
                                           struct key *dest_keyring,
                                           unsigned long flags)
@@ -348,7 +350,7 @@ static struct key *construct_key_and_link(struct key_type *type,
         key_user_put(user);
 
         if (ret == 0) {
-                ret = construct_key(key, callout_info, aux);
+                ret = construct_key(key, callout_info, callout_len, aux);
                 if (ret < 0)
                         goto construction_failed;
         }
@@ -370,7 +372,8 @@ construction_failed:
  */
 struct key *request_key_and_link(struct key_type *type,
                                  const char *description,
-                                 const char *callout_info,
+                                 const void *callout_info,
+                                 size_t callout_len,
                                  void *aux,
                                  struct key *dest_keyring,
                                  unsigned long flags)
@@ -378,8 +381,8 @@ struct key *request_key_and_link(struct key_type *type,
         struct key *key;
         key_ref_t key_ref;
 
-        kenter("%s,%s,%s,%p,%p,%lx",
-               type->name, description, callout_info, aux,
+        kenter("%s,%s,%p,%zu,%p,%p,%lx",
+               type->name, description, callout_info, callout_len, aux,
                dest_keyring, flags);
 
         /* search all the process keyrings for a key */
@@ -398,7 +401,8 @@ struct key *request_key_and_link(struct key_type *type,
                         goto error;
 
                 key = construct_key_and_link(type, description, callout_info,
-                                             aux, dest_keyring, flags);
+                                             callout_len, aux, dest_keyring,
+                                             flags);
         }
 
 error:
@@ -434,10 +438,13 @@ struct key *request_key(struct key_type *type,
                         const char *callout_info)
 {
         struct key *key;
+        size_t callout_len = 0;
         int ret;
 
-        key = request_key_and_link(type, description, callout_info, NULL,
-                                   NULL, KEY_ALLOC_IN_QUOTA);
+        if (callout_info)
+                callout_len = strlen(callout_info);
+        key = request_key_and_link(type, description, callout_info, callout_len,
+                                   NULL, NULL, KEY_ALLOC_IN_QUOTA);
         if (!IS_ERR(key)) {
                 ret = wait_for_key_construction(key, false);
                 if (ret < 0) {
@@ -458,14 +465,15 @@ EXPORT_SYMBOL(request_key);
  */
 struct key *request_key_with_auxdata(struct key_type *type,
                                      const char *description,
-                                     const char *callout_info,
+                                     const void *callout_info,
+                                     size_t callout_len,
                                      void *aux)
 {
         struct key *key;
         int ret;
 
-        key = request_key_and_link(type, description, callout_info, aux,
-                                   NULL, KEY_ALLOC_IN_QUOTA);
+        key = request_key_and_link(type, description, callout_info, callout_len,
+                                   aux, NULL, KEY_ALLOC_IN_QUOTA);
         if (!IS_ERR(key)) {
                 ret = wait_for_key_construction(key, false);
                 if (ret < 0) {
@@ -485,10 +493,12 @@ EXPORT_SYMBOL(request_key_with_auxdata);
  */
 struct key *request_key_async(struct key_type *type,
                               const char *description,
-                              const char *callout_info)
+                              const void *callout_info,
+                              size_t callout_len)
 {
-        return request_key_and_link(type, description, callout_info, NULL,
-                                    NULL, KEY_ALLOC_IN_QUOTA);
+        return request_key_and_link(type, description, callout_info,
+                                    callout_len, NULL, NULL,
+                                    KEY_ALLOC_IN_QUOTA);
 }
 EXPORT_SYMBOL(request_key_async);
 
@@ -500,10 +510,11 @@ EXPORT_SYMBOL(request_key_async);
  */
 struct key *request_key_async_with_auxdata(struct key_type *type,
                                            const char *description,
-                                           const char *callout_info,
+                                           const void *callout_info,
+                                           size_t callout_len,
                                            void *aux)
 {
-        return request_key_and_link(type, description, callout_info, aux,
-                                    NULL, KEY_ALLOC_IN_QUOTA);
+        return request_key_and_link(type, description, callout_info,
+                                    callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
 }
 EXPORT_SYMBOL(request_key_async_with_auxdata);
diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index e42b5252486f..c615d473ce7c 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -61,7 +61,7 @@ static void request_key_auth_describe(const struct key *key,
 
         seq_puts(m, "key:");
         seq_puts(m, key->description);
-        seq_printf(m, " pid:%d ci:%zu", rka->pid, strlen(rka->callout_info));
+        seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
 
 } /* end request_key_auth_describe() */
 
@@ -77,7 +77,7 @@ static long request_key_auth_read(const struct key *key,
         size_t datalen;
         long ret;
 
-        datalen = strlen(rka->callout_info);
+        datalen = rka->callout_len;
         ret = datalen;
 
         /* we can return the data as is */
@@ -137,7 +137,8 @@ static void request_key_auth_destroy(struct key *key)
  * create an authorisation token for /sbin/request-key or whoever to gain
  * access to the caller's security data
  */
-struct key *request_key_auth_new(struct key *target, const char *callout_info)
+struct key *request_key_auth_new(struct key *target, const void *callout_info,
+                                 size_t callout_len)
 {
         struct request_key_auth *rka, *irka;
         struct key *authkey = NULL;
@@ -152,7 +153,7 @@ struct key *request_key_auth_new(struct key *target, const char *callout_info)
                 kleave(" = -ENOMEM");
                 return ERR_PTR(-ENOMEM);
         }
-        rka->callout_info = kmalloc(strlen(callout_info) + 1, GFP_KERNEL);
+        rka->callout_info = kmalloc(callout_len, GFP_KERNEL);
         if (!rka->callout_info) {
                 kleave(" = -ENOMEM");
                 kfree(rka);
@@ -186,7 +187,8 @@ struct key *request_key_auth_new(struct key *target, const char *callout_info)
         }
 
         rka->target_key = key_get(target);
-        strcpy(rka->callout_info, callout_info);
+        memcpy(rka->callout_info, callout_info, callout_len);
+        rka->callout_len = callout_len;
 
         /* allocate the auth key */
         sprintf(desc, "%x", target->serial);