Re: [PATCH 2/2] strndup_user (v3), convert (keyctl)
From: Davi Arnaut
Date: Mon Feb 20 2006 - 15:07:13 EST
On Mon, 20 Feb 2006 10:38:16 +0000
David Howells <dhowells@xxxxxxxxxx> wrote:
> David Howells <dhowells@xxxxxxxxxx> wrote:
>
> > > I think you should just tell Andrew to drop
> > > keys-deal-properly-with-strnlen_user.patch
> > > in favor of mine... :-)
> >
> > No... you've taken out all the checks on lengths on NUL-terminated strings.
>
> I take that back... strndup not strdup.
>
> However, the check on the length of the type is wrong with your patch (and in
> the unpatched kernel). Can you pull in that bit from my patch?
In keyctl_keyring_search() there wasn't a check for type[0] == '.', but your
mm-patch added one implicitly. Which one is correct ?
>
> David
Convert security/keys/keyctl.c to use strndup_user() and moves
the type string duplication code to a function.
Signed-off-by: Davi Arnaut <davi.arnaut@xxxxxxxxx>
--
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 0c62798..ed71d86 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 _
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 ch
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
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
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);
-
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