[PATCH] strndup_user: convert keyctl

Copies user-space string with strndup_user() and moves the type string
duplication code to a function (thus fixing a wrong check on the length of the
type.)

Signed-off-by: Davi Arnaut <davi.arnaut@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 50 insertions, 105 deletions

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 0c62798ac7d8..ed71d86d2ce2 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -17,10 +17,33 @@
 #include <linux/keyctl.h>
 #include <linux/fs.h>
 #include <linux/capability.h>
+#include <linux/string.h>
 #include <linux/err.h>
 #include <asm/uaccess.h>
 #include "internal.h"
 
+static int key_get_type_from_user(char *type,
+                                  const char __user *_type,
+                                  unsigned len)
+{
+        int ret;
+
+        ret = strncpy_from_user(type, _type, len);
+
+        if (ret < 0)
+                return -EFAULT;
+
+        if (ret == 0 || ret >= len)
+                return -EINVAL;
+
+        if (type[0] == '.')
+                return -EPERM;
+
+        type[len - 1] = '\0';
+
+        return 0;
+}
+
 /*****************************************************************************/
 /*
  * extract the description of a new key from userspace and either add it as a
@@ -38,40 +61,22 @@ asmlinkage long sys_add_key(const char __user *_type,
         key_ref_t keyring_ref, key_ref;
         char type[32], *description;
         void *payload;
-        long dlen, ret;
+        long ret;
 
         ret = -EINVAL;
         if (plen > 32767)
                 goto error;
 
         /* draw all the data into kernel space */
-        ret = strncpy_from_user(type, _type, sizeof(type) - 1);
+        ret = key_get_type_from_user(type, _type, sizeof(type));
         if (ret < 0)
                 goto error;
-        type[31] = '\0';
-
-        ret = -EPERM;
-        if (type[0] == '.')
-                goto error;
-
-        ret = -EFAULT;
-        dlen = strnlen_user(_description, PAGE_SIZE - 1);
-        if (dlen <= 0)
-                goto error;
 
-        ret = -EINVAL;
-        if (dlen > PAGE_SIZE - 1)
-                goto error;
-
-        ret = -ENOMEM;
-        description = kmalloc(dlen + 1, GFP_KERNEL);
-        if (!description)
+        description = strndup_user(_description, PAGE_SIZE);
+        if (IS_ERR(description)) {
+                ret = PTR_ERR(description);
                 goto error;
-        description[dlen] = '\0';
-
-        ret = -EFAULT;
-        if (copy_from_user(description, _description, dlen) != 0)
-                goto error2;
+        }
 
         /* pull the payload in if one was supplied */
         payload = NULL;
@@ -136,59 +141,28 @@ asmlinkage long sys_request_key(const char __user *_type,
         struct key *key;
         key_ref_t dest_ref;
         char type[32], *description, *callout_info;
-        long dlen, ret;
+        long ret;
 
         /* pull the type into kernel space */
-        ret = strncpy_from_user(type, _type, sizeof(type) - 1);
+        ret = key_get_type_from_user(type, _type, sizeof(type));
         if (ret < 0)
                 goto error;
-        type[31] = '\0';
-
-        ret = -EPERM;
-        if (type[0] == '.')
-                goto error;
 
         /* pull the description into kernel space */
-        ret = -EFAULT;
-        dlen = strnlen_user(_description, PAGE_SIZE - 1);
-        if (dlen <= 0)
-                goto error;
-
-        ret = -EINVAL;
-        if (dlen > PAGE_SIZE - 1)
-                goto error;
-
-        ret = -ENOMEM;
-        description = kmalloc(dlen + 1, GFP_KERNEL);
-        if (!description)
+        description = strndup_user(_description, PAGE_SIZE);
+        if (IS_ERR(description)) {
+                ret = PTR_ERR(description);
                 goto error;
-        description[dlen] = '\0';
-
-        ret = -EFAULT;
-        if (copy_from_user(description, _description, dlen) != 0)
-                goto error2;
+        }
 
         /* pull the callout info into kernel space */
         callout_info = NULL;
         if (_callout_info) {
-                ret = -EFAULT;
-                dlen = strnlen_user(_callout_info, PAGE_SIZE - 1);
-                if (dlen <= 0)
-                        goto error2;
-
-                ret = -EINVAL;
-                if (dlen > PAGE_SIZE - 1)
-                        goto error2;
-
-                ret = -ENOMEM;
-                callout_info = kmalloc(dlen + 1, GFP_KERNEL);
-                if (!callout_info)
+                callout_info = strndup_user(_callout_info, PAGE_SIZE);
+                if (IS_ERR(callout_info)) {
+                        ret = PTR_ERR(callout_info);
                         goto error2;
-                callout_info[dlen] = '\0';
-
-                ret = -EFAULT;
-                if (copy_from_user(callout_info, _callout_info, dlen) != 0)
-                        goto error3;
+                }
         }
 
         /* get the destination keyring if specified */
@@ -264,36 +238,21 @@ long keyctl_get_keyring_ID(key_serial_t id, int create)
 long keyctl_join_session_keyring(const char __user *_name)
 {
         char *name;
-        long nlen, ret;
+        long ret;
 
         /* fetch the name from userspace */
         name = NULL;
         if (_name) {
-                ret = -EFAULT;
-                nlen = strnlen_user(_name, PAGE_SIZE - 1);
-                if (nlen <= 0)
-                        goto error;
-
-                ret = -EINVAL;
-                if (nlen > PAGE_SIZE - 1)
+                name = strndup_user(_name, PAGE_SIZE);
+                if (IS_ERR(name)) {
+                        ret = PTR_ERR(name);
                         goto error;
-
-                ret = -ENOMEM;
-                name = kmalloc(nlen + 1, GFP_KERNEL);
-                if (!name)
-                        goto error;
-                name[nlen] = '\0';
-
-                ret = -EFAULT;
-                if (copy_from_user(name, _name, nlen) != 0)
-                        goto error2;
+                }
         }
 
         /* join the session */
         ret = join_session_keyring(name);
 
- error2:
-        kfree(name);
  error:
         return ret;
 
@@ -566,32 +525,18 @@ long keyctl_keyring_search(key_serial_t ringid,
         struct key_type *ktype;
         key_ref_t keyring_ref, key_ref, dest_ref;
         char type[32], *description;
-        long dlen, ret;
+        long ret;
 
         /* pull the type and description into kernel space */
-        ret = strncpy_from_user(type, _type, sizeof(type) - 1);
+        ret = key_get_type_from_user(type, _type, sizeof(type));
         if (ret < 0)
                 goto error;
-        type[31] = '\0';
 
-        ret = -EFAULT;
-        dlen = strnlen_user(_description, PAGE_SIZE - 1);
-        if (dlen <= 0)
+        description = strndup_user(_description, PAGE_SIZE);
+        if (IS_ERR(description)) {
+                ret = PTR_ERR(description);
                 goto error;
-
-        ret = -EINVAL;
-        if (dlen > PAGE_SIZE - 1)
-                goto error;
-
-        ret = -ENOMEM;
-        description = kmalloc(dlen + 1, GFP_KERNEL);
-        if (!description)
-                goto error;
-        description[dlen] = '\0';
-
-        ret = -EFAULT;
-        if (copy_from_user(description, _description, dlen) != 0)
-                goto error2;
+        }
 
         /* get the keyring at which to begin the search */
         keyring_ref = lookup_user_key(NULL, ringid, 0, 0, KEY_SEARCH);