lkml.org 
[lkml]   [2020]   [Mar]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v4 2/4] KEYS: Remove __user annotation from rxrpc_read()
Date
As the keyctl_read_key() has been modified to use a temporary kernel
buffer to read out the key data instead of passing in the user-supplied
buffer directly, there is no need to use the __user annotation for
rxrpc_read(). In addition,

1) The put_user() call is replaced by a direct copy.
2) The copy_to_user() call is replaced by memcpy().
3) All the fault handling code is removed.

Compiling on a x86-64 system, the size of the rxrpc_read() function is
reduced from 3795 bytes to 2384 bytes with this patch.

Signed-off-by: Waiman Long <longman@redhat.com>
---
net/rxrpc/key.c | 27 +++++++++------------------
1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/net/rxrpc/key.c b/net/rxrpc/key.c
index 6c3f35fac42d..0c98313dd7a8 100644
--- a/net/rxrpc/key.c
+++ b/net/rxrpc/key.c
@@ -31,7 +31,7 @@ static void rxrpc_free_preparse_s(struct key_preparsed_payload *);
static void rxrpc_destroy(struct key *);
static void rxrpc_destroy_s(struct key *);
static void rxrpc_describe(const struct key *, struct seq_file *);
-static long rxrpc_read(const struct key *, char __user *, size_t);
+static long rxrpc_read(const struct key *, char *, size_t);

/*
* rxrpc defined keys take an arbitrary string as the description and an
@@ -1042,12 +1042,12 @@ EXPORT_SYMBOL(rxrpc_get_null_key);
* - this returns the result in XDR form
*/
static long rxrpc_read(const struct key *key,
- char __user *buffer, size_t buflen)
+ char *buffer, size_t buflen)
{
const struct rxrpc_key_token *token;
const struct krb5_principal *princ;
size_t size;
- __be32 __user *xdr, *oldxdr;
+ __be32 *xdr, *oldxdr;
u32 cnlen, toksize, ntoks, tok, zero;
u16 toksizes[AFSTOKEN_MAX];
int loop;
@@ -1124,30 +1124,25 @@ static long rxrpc_read(const struct key *key,
if (!buffer || buflen < size)
return size;

- xdr = (__be32 __user *) buffer;
+ xdr = (__be32 *)buffer;
zero = 0;
#define ENCODE(x) \
do { \
- __be32 y = htonl(x); \
- if (put_user(y, xdr++) < 0) \
- goto fault; \
+ *xdr++ = htonl(x); \
} while(0)
#define ENCODE_DATA(l, s) \
do { \
u32 _l = (l); \
ENCODE(l); \
- if (copy_to_user(xdr, (s), _l) != 0) \
- goto fault; \
- if (_l & 3 && \
- copy_to_user((u8 __user *)xdr + _l, &zero, 4 - (_l & 3)) != 0) \
- goto fault; \
+ memcpy(xdr, (s), _l); \
+ if (_l & 3) \
+ memcpy((u8 *)xdr + _l, &zero, 4 - (_l & 3)); \
xdr += (_l + 3) >> 2; \
} while(0)
#define ENCODE64(x) \
do { \
__be64 y = cpu_to_be64(x); \
- if (copy_to_user(xdr, &y, 8) != 0) \
- goto fault; \
+ memcpy(xdr, &y, 8); \
xdr += 8 >> 2; \
} while(0)
#define ENCODE_STR(s) \
@@ -1238,8 +1233,4 @@ static long rxrpc_read(const struct key *key,
ASSERTCMP((char __user *) xdr - buffer, ==, size);
_leave(" = %zu", size);
return size;
-
-fault:
- _leave(" = -EFAULT");
- return -EFAULT;
}
--
2.18.1
\
 
 \ /
  Last update: 2020-03-17 20:43    [W:0.081 / U:0.632 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site