keys: increase the payload size when instantiating a key

Increase the size of a payload that can be used to instantiate a key in
add_key() and keyctl_instantiate_key().  This permits huge CIFS SPNEGO blobs
to be passed around.  The limit is raised to 1MB.  If kmalloc() can't allocate
a buffer of sufficient size, vmalloc() will be tried instead.

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>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 30 insertions, 8 deletions

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index d9ca15c109cc..8ec84326a983 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -19,6 +19,7 @@
 #include <linux/capability.h>
 #include <linux/string.h>
 #include <linux/err.h>
+#include <linux/vmalloc.h>
 #include <asm/uaccess.h>
 #include "internal.h"
 
@@ -62,9 +63,10 @@ asmlinkage long sys_add_key(const char __user *_type,
         char type[32], *description;
         void *payload;
         long ret;
+        bool vm;
 
         ret = -EINVAL;
-        if (plen > 32767)
+        if (plen > 1024 * 1024 - 1)
                 goto error;
 
         /* draw all the data into kernel space */
@@ -81,11 +83,18 @@ asmlinkage long sys_add_key(const char __user *_type,
         /* pull the payload in if one was supplied */
         payload = NULL;
 
+        vm = false;
         if (_payload) {
                 ret = -ENOMEM;
                 payload = kmalloc(plen, GFP_KERNEL);
-                if (!payload)
-                        goto error2;
+                if (!payload) {
+                        if (plen <= PAGE_SIZE)
+                                goto error2;
+                        vm = true;
+                        payload = vmalloc(plen);
+                        if (!payload)
+                                goto error2;
+                }
 
                 ret = -EFAULT;
                 if (copy_from_user(payload, _payload, plen) != 0)
@@ -113,7 +122,10 @@ asmlinkage long sys_add_key(const char __user *_type,
 
         key_ref_put(keyring_ref);
  error3:
-        kfree(payload);
+        if (!vm)
+                kfree(payload);
+        else
+                vfree(payload);
  error2:
         kfree(description);
  error:
@@ -821,9 +833,10 @@ long keyctl_instantiate_key(key_serial_t id,
         key_ref_t keyring_ref;
         void *payload;
         long ret;
+        bool vm = false;
 
         ret = -EINVAL;
-        if (plen > 32767)
+        if (plen > 1024 * 1024 - 1)
                 goto error;
 
         /* the appropriate instantiation authorisation key must have been
@@ -843,8 +856,14 @@ long keyctl_instantiate_key(key_serial_t id,
         if (_payload) {
                 ret = -ENOMEM;
                 payload = kmalloc(plen, GFP_KERNEL);
-                if (!payload)
-                        goto error;
+                if (!payload) {
+                        if (plen <= PAGE_SIZE)
+                                goto error;
+                        vm = true;
+                        payload = vmalloc(plen);
+                        if (!payload)
+                                goto error;
+                }
 
                 ret = -EFAULT;
                 if (copy_from_user(payload, _payload, plen) != 0)
@@ -877,7 +896,10 @@ long keyctl_instantiate_key(key_serial_t id,
         }
 
 error2:
-        kfree(payload);
+        if (!vm)
+                kfree(payload);
+        else
+                vfree(payload);
 error:
         return ret;