提交 725f2865 编写于 作者: K Kevin Coffman 提交者: Trond Myklebust

gss_krb5: Introduce encryption type framework

Make the client and server code consistent regarding the extra buffer
space made available for the auth code when wrapping data.

Add some comments/documentation about the available buffer space
in the xdr_buf head and tail when gss_wrap is called.

Add a compile-time check to make sure we are not exceeding the available
buffer space.

Add a central function to shift head data.
Signed-off-by: NKevin Coffman <kwc@citi.umich.edu>
Signed-off-by: NSteve Dickson <steved@redhat.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
上级 4fc4c3ce
......@@ -40,6 +40,12 @@
#include <linux/sunrpc/gss_err.h>
#include <linux/sunrpc/gss_asn1.h>
/* Maximum checksum function output for the supported crypto algorithms */
#define GSS_KRB5_MAX_CKSUM_LEN (20)
/* Maximum blocksize for the supported crypto algorithms */
#define GSS_KRB5_MAX_BLOCKSIZE (16)
struct krb5_ctx {
int initiate; /* 1 = initiating, 0 = accepting */
struct crypto_blkcipher *enc;
......@@ -113,6 +119,22 @@ enum seal_alg {
#define ENCTYPE_DES3_CBC_SHA1 0x0010
#define ENCTYPE_UNKNOWN 0x01ff
/*
* This compile-time check verifies that we will not exceed the
* slack space allotted by the client and server auth_gss code
* before they call gss_wrap().
*/
#define GSS_KRB5_MAX_SLACK_NEEDED \
(GSS_KRB5_TOK_HDR_LEN /* gss token header */ \
+ GSS_KRB5_MAX_CKSUM_LEN /* gss token checksum */ \
+ GSS_KRB5_MAX_BLOCKSIZE /* confounder */ \
+ GSS_KRB5_MAX_BLOCKSIZE /* possible padding */ \
+ GSS_KRB5_TOK_HDR_LEN /* encrypted hdr in v2 token */\
+ GSS_KRB5_MAX_CKSUM_LEN /* encryption hmac */ \
+ 4 + 4 /* RPC verifier */ \
+ GSS_KRB5_TOK_HDR_LEN \
+ GSS_KRB5_MAX_CKSUM_LEN)
s32
make_checksum(char *, char *header, int hdrlen, struct xdr_buf *body,
int body_offset, struct xdr_netobj *cksum);
......@@ -157,3 +179,6 @@ s32
krb5_get_seq_num(struct crypto_blkcipher *key,
unsigned char *cksum,
unsigned char *buf, int *direction, u32 *seqnum);
int
xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen);
......@@ -61,7 +61,7 @@ static const struct rpc_credops gss_nullops;
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
#define GSS_CRED_SLACK 1024
#define GSS_CRED_SLACK (RPC_MAX_AUTH_SIZE * 2)
/* length of a krb5 verifier (48), plus data added before arguments when
* using integrity (two 4-byte integers): */
#define GSS_VERF_SLACK 100
......
......@@ -325,3 +325,41 @@ gss_decrypt_xdr_buf(struct crypto_blkcipher *tfm, struct xdr_buf *buf,
return xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc);
}
/*
* This function makes the assumption that it was ultimately called
* from gss_wrap().
*
* The client auth_gss code moves any existing tail data into a
* separate page before calling gss_wrap.
* The server svcauth_gss code ensures that both the head and the
* tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap.
*
* Even with that guarantee, this function may be called more than
* once in the processing of gss_wrap(). The best we can do is
* verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the
* largest expected shift will fit within RPC_MAX_AUTH_SIZE.
* At run-time we can verify that a single invocation of this
* function doesn't attempt to use more the RPC_MAX_AUTH_SIZE.
*/
int
xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen)
{
u8 *p;
if (shiftlen == 0)
return 0;
BUILD_BUG_ON(GSS_KRB5_MAX_SLACK_NEEDED > RPC_MAX_AUTH_SIZE);
BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE);
p = buf->head[0].iov_base + base;
memmove(p + shiftlen, p, buf->head[0].iov_len - base);
buf->head[0].iov_len += shiftlen;
buf->len += shiftlen;
return 0;
}
......@@ -155,11 +155,9 @@ gss_wrap_kerberos(struct gss_ctx *ctx, int offset,
ptr = buf->head[0].iov_base + offset;
/* shift data to make room for header. */
xdr_extend_head(buf, offset, headlen);
/* XXX Would be cleverer to encrypt while copying. */
/* XXX bounds checking, slack, etc. */
memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset);
buf->head[0].iov_len += headlen;
buf->len += headlen;
BUG_ON((buf->len - offset - headlen) % blocksize);
g_make_token_header(&kctx->mech_used,
......
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