2008-04-30 16:45:54

by Kevin Coffman

[permalink] [raw]
Subject: [enctypes round 2: PATCH 01/26] gss_krb5: create a define for token header size and clean up ptr location

cleanup:
Document token header size with a #define instead of open-coding it.

Don't needlessly increment "ptr" past the beginning of the header
which makes the values passed to functions more understandable and
eliminates the need for extra "krb5_hdr" pointer.

Clean up some intersecting white-space issues flagged by checkpatch.pl.

This leaves the checksum length hard-coded at 8 for DES. A later patch
cleans that up.

Signed-off-by: Kevin Coffman <[email protected]>
---

include/linux/sunrpc/gss_krb5.h | 3 ++
net/sunrpc/auth_gss/gss_krb5_seal.c | 26 +++++++++--------
net/sunrpc/auth_gss/gss_krb5_unseal.c | 16 +++++------
net/sunrpc/auth_gss/gss_krb5_wrap.c | 50 +++++++++++++++++----------------
4 files changed, 49 insertions(+), 46 deletions(-)

diff --git a/include/linux/sunrpc/gss_krb5.h b/include/linux/sunrpc/gss_krb5.h
index a10f1fb..e7bbdba 100644
--- a/include/linux/sunrpc/gss_krb5.h
+++ b/include/linux/sunrpc/gss_krb5.h
@@ -51,6 +51,9 @@ struct krb5_ctx {

extern spinlock_t krb5_seq_lock;

+/* The length of the Kerberos GSS token header */
+#define GSS_KRB5_TOK_HDR_LEN (16)
+
#define KG_TOK_MIC_MSG 0x0101
#define KG_TOK_WRAP_MSG 0x0201

diff --git a/net/sunrpc/auth_gss/gss_krb5_seal.c b/net/sunrpc/auth_gss/gss_krb5_seal.c
index 5f1d36d..b8f42ef 100644
--- a/net/sunrpc/auth_gss/gss_krb5_seal.c
+++ b/net/sunrpc/auth_gss/gss_krb5_seal.c
@@ -78,7 +78,7 @@ gss_get_mic_kerberos(struct gss_ctx *gss_ctx, struct xdr_buf *text,
struct krb5_ctx *ctx = gss_ctx->internal_ctx_id;
char cksumdata[16];
struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata};
- unsigned char *ptr, *krb5_hdr, *msg_start;
+ unsigned char *ptr, *msg_start;
s32 now;
u32 seq_send;

@@ -87,36 +87,36 @@ gss_get_mic_kerberos(struct gss_ctx *gss_ctx, struct xdr_buf *text,

now = get_seconds();

- token->len = g_token_size(&ctx->mech_used, 24);
+ token->len = g_token_size(&ctx->mech_used, GSS_KRB5_TOK_HDR_LEN + 8);

ptr = token->data;
- g_make_token_header(&ctx->mech_used, 24, &ptr);
+ g_make_token_header(&ctx->mech_used, GSS_KRB5_TOK_HDR_LEN + 8, &ptr);

- *ptr++ = (unsigned char) ((KG_TOK_MIC_MSG>>8)&0xff);
- *ptr++ = (unsigned char) (KG_TOK_MIC_MSG&0xff);
+ /* ptr now at header described in rfc 1964, section 1.2.1: */
+ ptr[0] = (unsigned char) ((KG_TOK_MIC_MSG >> 8) & 0xff);
+ ptr[1] = (unsigned char) (KG_TOK_MIC_MSG & 0xff);

- /* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */
- krb5_hdr = ptr - 2;
- msg_start = krb5_hdr + 24;
+ msg_start = ptr + GSS_KRB5_TOK_HDR_LEN + 8;

- *(__be16 *)(krb5_hdr + 2) = htons(SGN_ALG_DES_MAC_MD5);
- memset(krb5_hdr + 4, 0xff, 4);
+ *(__be16 *)(ptr + 2) = htons(SGN_ALG_DES_MAC_MD5);
+ memset(ptr + 4, 0xff, 4);

- if (make_checksum("md5", krb5_hdr, 8, text, 0, &md5cksum))
+ if (make_checksum("md5", ptr, 8, text, 0, &md5cksum))
return GSS_S_FAILURE;

if (krb5_encrypt(ctx->seq, NULL, md5cksum.data,
md5cksum.data, md5cksum.len))
return GSS_S_FAILURE;

- memcpy(krb5_hdr + 16, md5cksum.data + md5cksum.len - 8, 8);
+ memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data + md5cksum.len - 8, 8);

spin_lock(&krb5_seq_lock);
seq_send = ctx->seq_send++;
spin_unlock(&krb5_seq_lock);

if (krb5_make_seq_num(ctx->seq, ctx->initiate ? 0 : 0xff,
- seq_send, krb5_hdr + 16, krb5_hdr + 8))
+ seq_send, ptr + GSS_KRB5_TOK_HDR_LEN,
+ ptr + 8))
return GSS_S_FAILURE;

return (ctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
diff --git a/net/sunrpc/auth_gss/gss_krb5_unseal.c b/net/sunrpc/auth_gss/gss_krb5_unseal.c
index d91a5d0..066ec73 100644
--- a/net/sunrpc/auth_gss/gss_krb5_unseal.c
+++ b/net/sunrpc/auth_gss/gss_krb5_unseal.c
@@ -92,30 +92,30 @@ gss_verify_mic_kerberos(struct gss_ctx *gss_ctx,
read_token->len))
return GSS_S_DEFECTIVE_TOKEN;

- if ((*ptr++ != ((KG_TOK_MIC_MSG>>8)&0xff)) ||
- (*ptr++ != ( KG_TOK_MIC_MSG &0xff)) )
+ if ((ptr[0] != ((KG_TOK_MIC_MSG >> 8) & 0xff)) ||
+ (ptr[1] != (KG_TOK_MIC_MSG & 0xff)))
return GSS_S_DEFECTIVE_TOKEN;

/* XXX sanity-check bodysize?? */

- signalg = ptr[0] + (ptr[1] << 8);
+ signalg = ptr[2] + (ptr[3] << 8);
if (signalg != SGN_ALG_DES_MAC_MD5)
return GSS_S_DEFECTIVE_TOKEN;

- sealalg = ptr[2] + (ptr[3] << 8);
+ sealalg = ptr[4] + (ptr[5] << 8);
if (sealalg != SEAL_ALG_NONE)
return GSS_S_DEFECTIVE_TOKEN;

- if ((ptr[4] != 0xff) || (ptr[5] != 0xff))
+ if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
return GSS_S_DEFECTIVE_TOKEN;

- if (make_checksum("md5", ptr - 2, 8, message_buffer, 0, &md5cksum))
+ if (make_checksum("md5", ptr, 8, message_buffer, 0, &md5cksum))
return GSS_S_FAILURE;

if (krb5_encrypt(ctx->seq, NULL, md5cksum.data, md5cksum.data, 16))
return GSS_S_FAILURE;

- if (memcmp(md5cksum.data + 8, ptr + 14, 8))
+ if (memcmp(md5cksum.data + 8, ptr + GSS_KRB5_TOK_HDR_LEN, 8))
return GSS_S_BAD_SIG;

/* it got through unscathed. Make sure the context is unexpired */
@@ -127,7 +127,7 @@ gss_verify_mic_kerberos(struct gss_ctx *gss_ctx,

/* do sequencing checks */

- if (krb5_get_seq_num(ctx->seq, ptr + 14, ptr + 6, &direction, &seqnum))
+ if (krb5_get_seq_num(ctx->seq, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8, &direction, &seqnum))
return GSS_S_FAILURE;

if ((ctx->initiate && direction != 0xff) ||
diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
index b00b1b4..283cb25 100644
--- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
+++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
@@ -122,7 +122,7 @@ gss_wrap_kerberos(struct gss_ctx *ctx, int offset,
char cksumdata[16];
struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata};
int blocksize = 0, plainlen;
- unsigned char *ptr, *krb5_hdr, *msg_start;
+ unsigned char *ptr, *msg_start;
s32 now;
int headlen;
struct page **tmp_pages;
@@ -149,26 +149,26 @@ gss_wrap_kerberos(struct gss_ctx *ctx, int offset,
buf->len += headlen;
BUG_ON((buf->len - offset - headlen) % blocksize);

- g_make_token_header(&kctx->mech_used, 24 + plainlen, &ptr);
+ g_make_token_header(&kctx->mech_used,
+ GSS_KRB5_TOK_HDR_LEN + 8 + plainlen, &ptr);


- *ptr++ = (unsigned char) ((KG_TOK_WRAP_MSG>>8)&0xff);
- *ptr++ = (unsigned char) (KG_TOK_WRAP_MSG&0xff);
+ /* ptr now at header described in rfc 1964, section 1.2.1: */
+ ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff);
+ ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff);

- /* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */
- krb5_hdr = ptr - 2;
- msg_start = krb5_hdr + 24;
+ msg_start = ptr + 24;

- *(__be16 *)(krb5_hdr + 2) = htons(SGN_ALG_DES_MAC_MD5);
- memset(krb5_hdr + 4, 0xff, 4);
- *(__be16 *)(krb5_hdr + 4) = htons(SEAL_ALG_DES);
+ *(__be16 *)(ptr + 2) = htons(SGN_ALG_DES_MAC_MD5);
+ memset(ptr + 4, 0xff, 4);
+ *(__be16 *)(ptr + 4) = htons(SEAL_ALG_DES);

make_confounder(msg_start, blocksize);

/* XXXJBF: UGH!: */
tmp_pages = buf->pages;
buf->pages = pages;
- if (make_checksum("md5", krb5_hdr, 8, buf,
+ if (make_checksum("md5", ptr, 8, buf,
offset + headlen - blocksize, &md5cksum))
return GSS_S_FAILURE;
buf->pages = tmp_pages;
@@ -176,7 +176,7 @@ gss_wrap_kerberos(struct gss_ctx *ctx, int offset,
if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
md5cksum.data, md5cksum.len))
return GSS_S_FAILURE;
- memcpy(krb5_hdr + 16, md5cksum.data + md5cksum.len - 8, 8);
+ memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data + md5cksum.len - 8, 8);

spin_lock(&krb5_seq_lock);
seq_send = kctx->seq_send++;
@@ -185,7 +185,7 @@ gss_wrap_kerberos(struct gss_ctx *ctx, int offset,
/* XXX would probably be more efficient to compute checksum
* and encrypt at the same time: */
if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff,
- seq_send, krb5_hdr + 16, krb5_hdr + 8)))
+ seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8)))
return GSS_S_FAILURE;

if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize,
@@ -219,38 +219,38 @@ gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf)
buf->len - offset))
return GSS_S_DEFECTIVE_TOKEN;

- if ((*ptr++ != ((KG_TOK_WRAP_MSG>>8)&0xff)) ||
- (*ptr++ != (KG_TOK_WRAP_MSG &0xff)) )
+ if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
+ (ptr[1] != (KG_TOK_WRAP_MSG & 0xff)))
return GSS_S_DEFECTIVE_TOKEN;

/* XXX sanity-check bodysize?? */

/* get the sign and seal algorithms */

- signalg = ptr[0] + (ptr[1] << 8);
+ signalg = ptr[2] + (ptr[3] << 8);
if (signalg != SGN_ALG_DES_MAC_MD5)
return GSS_S_DEFECTIVE_TOKEN;

- sealalg = ptr[2] + (ptr[3] << 8);
+ sealalg = ptr[4] + (ptr[5] << 8);
if (sealalg != SEAL_ALG_DES)
return GSS_S_DEFECTIVE_TOKEN;

- if ((ptr[4] != 0xff) || (ptr[5] != 0xff))
+ if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
return GSS_S_DEFECTIVE_TOKEN;

if (gss_decrypt_xdr_buf(kctx->enc, buf,
- ptr + 22 - (unsigned char *)buf->head[0].iov_base))
+ ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base))
return GSS_S_DEFECTIVE_TOKEN;

- if (make_checksum("md5", ptr - 2, 8, buf,
- ptr + 22 - (unsigned char *)buf->head[0].iov_base, &md5cksum))
+ if (make_checksum("md5", ptr, 8, buf,
+ ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base, &md5cksum))
return GSS_S_FAILURE;

if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
md5cksum.data, md5cksum.len))
return GSS_S_FAILURE;

- if (memcmp(md5cksum.data + 8, ptr + 14, 8))
+ if (memcmp(md5cksum.data + 8, ptr + GSS_KRB5_TOK_HDR_LEN, 8))
return GSS_S_BAD_SIG;

/* it got through unscathed. Make sure the context is unexpired */
@@ -262,8 +262,8 @@ gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf)

/* do sequencing checks */

- if (krb5_get_seq_num(kctx->seq, ptr + 14, ptr + 6, &direction,
- &seqnum))
+ if (krb5_get_seq_num(kctx->seq, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8,
+ &direction, &seqnum))
return GSS_S_BAD_SIG;

if ((kctx->initiate && direction != 0xff) ||
@@ -274,7 +274,7 @@ gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf)
* better to copy and encrypt at the same time. */

blocksize = crypto_blkcipher_blocksize(kctx->enc);
- data_start = ptr + 22 + blocksize;
+ data_start = ptr + GSS_KRB5_TOK_HDR_LEN + 8 + blocksize;
orig_start = buf->head[0].iov_base + offset;
data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
memmove(orig_start, data_start, data_len);



2008-05-02 20:15:09

by J . Bruce Fields

[permalink] [raw]
Subject: Re: [enctypes round 2: PATCH 01/26] gss_krb5: create a define for token header size and clean up ptr location

On Wed, Apr 30, 2008 at 12:45:53PM -0400, Kevin Coffman wrote:
> cleanup:
> Document token header size with a #define instead of open-coding it.
>
> Don't needlessly increment "ptr" past the beginning of the header
> which makes the values passed to functions more understandable and
> eliminates the need for extra "krb5_hdr" pointer.
>
> Clean up some intersecting white-space issues flagged by checkpatch.pl.
>
> This leaves the checksum length hard-coded at 8 for DES. A later patch
> cleans that up.

Yes, looks like an improvement; applied.--b.

>
> Signed-off-by: Kevin Coffman <[email protected]>
> ---
>
> include/linux/sunrpc/gss_krb5.h | 3 ++
> net/sunrpc/auth_gss/gss_krb5_seal.c | 26 +++++++++--------
> net/sunrpc/auth_gss/gss_krb5_unseal.c | 16 +++++------
> net/sunrpc/auth_gss/gss_krb5_wrap.c | 50 +++++++++++++++++----------------
> 4 files changed, 49 insertions(+), 46 deletions(-)
>
> diff --git a/include/linux/sunrpc/gss_krb5.h b/include/linux/sunrpc/gss_krb5.h
> index a10f1fb..e7bbdba 100644
> --- a/include/linux/sunrpc/gss_krb5.h
> +++ b/include/linux/sunrpc/gss_krb5.h
> @@ -51,6 +51,9 @@ struct krb5_ctx {
>
> extern spinlock_t krb5_seq_lock;
>
> +/* The length of the Kerberos GSS token header */
> +#define GSS_KRB5_TOK_HDR_LEN (16)
> +
> #define KG_TOK_MIC_MSG 0x0101
> #define KG_TOK_WRAP_MSG 0x0201
>
> diff --git a/net/sunrpc/auth_gss/gss_krb5_seal.c b/net/sunrpc/auth_gss/gss_krb5_seal.c
> index 5f1d36d..b8f42ef 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_seal.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_seal.c
> @@ -78,7 +78,7 @@ gss_get_mic_kerberos(struct gss_ctx *gss_ctx, struct xdr_buf *text,
> struct krb5_ctx *ctx = gss_ctx->internal_ctx_id;
> char cksumdata[16];
> struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata};
> - unsigned char *ptr, *krb5_hdr, *msg_start;
> + unsigned char *ptr, *msg_start;
> s32 now;
> u32 seq_send;
>
> @@ -87,36 +87,36 @@ gss_get_mic_kerberos(struct gss_ctx *gss_ctx, struct xdr_buf *text,
>
> now = get_seconds();
>
> - token->len = g_token_size(&ctx->mech_used, 24);
> + token->len = g_token_size(&ctx->mech_used, GSS_KRB5_TOK_HDR_LEN + 8);
>
> ptr = token->data;
> - g_make_token_header(&ctx->mech_used, 24, &ptr);
> + g_make_token_header(&ctx->mech_used, GSS_KRB5_TOK_HDR_LEN + 8, &ptr);
>
> - *ptr++ = (unsigned char) ((KG_TOK_MIC_MSG>>8)&0xff);
> - *ptr++ = (unsigned char) (KG_TOK_MIC_MSG&0xff);
> + /* ptr now at header described in rfc 1964, section 1.2.1: */
> + ptr[0] = (unsigned char) ((KG_TOK_MIC_MSG >> 8) & 0xff);
> + ptr[1] = (unsigned char) (KG_TOK_MIC_MSG & 0xff);
>
> - /* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */
> - krb5_hdr = ptr - 2;
> - msg_start = krb5_hdr + 24;
> + msg_start = ptr + GSS_KRB5_TOK_HDR_LEN + 8;
>
> - *(__be16 *)(krb5_hdr + 2) = htons(SGN_ALG_DES_MAC_MD5);
> - memset(krb5_hdr + 4, 0xff, 4);
> + *(__be16 *)(ptr + 2) = htons(SGN_ALG_DES_MAC_MD5);
> + memset(ptr + 4, 0xff, 4);
>
> - if (make_checksum("md5", krb5_hdr, 8, text, 0, &md5cksum))
> + if (make_checksum("md5", ptr, 8, text, 0, &md5cksum))
> return GSS_S_FAILURE;
>
> if (krb5_encrypt(ctx->seq, NULL, md5cksum.data,
> md5cksum.data, md5cksum.len))
> return GSS_S_FAILURE;
>
> - memcpy(krb5_hdr + 16, md5cksum.data + md5cksum.len - 8, 8);
> + memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data + md5cksum.len - 8, 8);
>
> spin_lock(&krb5_seq_lock);
> seq_send = ctx->seq_send++;
> spin_unlock(&krb5_seq_lock);
>
> if (krb5_make_seq_num(ctx->seq, ctx->initiate ? 0 : 0xff,
> - seq_send, krb5_hdr + 16, krb5_hdr + 8))
> + seq_send, ptr + GSS_KRB5_TOK_HDR_LEN,
> + ptr + 8))
> return GSS_S_FAILURE;
>
> return (ctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
> diff --git a/net/sunrpc/auth_gss/gss_krb5_unseal.c b/net/sunrpc/auth_gss/gss_krb5_unseal.c
> index d91a5d0..066ec73 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_unseal.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_unseal.c
> @@ -92,30 +92,30 @@ gss_verify_mic_kerberos(struct gss_ctx *gss_ctx,
> read_token->len))
> return GSS_S_DEFECTIVE_TOKEN;
>
> - if ((*ptr++ != ((KG_TOK_MIC_MSG>>8)&0xff)) ||
> - (*ptr++ != ( KG_TOK_MIC_MSG &0xff)) )
> + if ((ptr[0] != ((KG_TOK_MIC_MSG >> 8) & 0xff)) ||
> + (ptr[1] != (KG_TOK_MIC_MSG & 0xff)))
> return GSS_S_DEFECTIVE_TOKEN;
>
> /* XXX sanity-check bodysize?? */
>
> - signalg = ptr[0] + (ptr[1] << 8);
> + signalg = ptr[2] + (ptr[3] << 8);
> if (signalg != SGN_ALG_DES_MAC_MD5)
> return GSS_S_DEFECTIVE_TOKEN;
>
> - sealalg = ptr[2] + (ptr[3] << 8);
> + sealalg = ptr[4] + (ptr[5] << 8);
> if (sealalg != SEAL_ALG_NONE)
> return GSS_S_DEFECTIVE_TOKEN;
>
> - if ((ptr[4] != 0xff) || (ptr[5] != 0xff))
> + if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
> return GSS_S_DEFECTIVE_TOKEN;
>
> - if (make_checksum("md5", ptr - 2, 8, message_buffer, 0, &md5cksum))
> + if (make_checksum("md5", ptr, 8, message_buffer, 0, &md5cksum))
> return GSS_S_FAILURE;
>
> if (krb5_encrypt(ctx->seq, NULL, md5cksum.data, md5cksum.data, 16))
> return GSS_S_FAILURE;
>
> - if (memcmp(md5cksum.data + 8, ptr + 14, 8))
> + if (memcmp(md5cksum.data + 8, ptr + GSS_KRB5_TOK_HDR_LEN, 8))
> return GSS_S_BAD_SIG;
>
> /* it got through unscathed. Make sure the context is unexpired */
> @@ -127,7 +127,7 @@ gss_verify_mic_kerberos(struct gss_ctx *gss_ctx,
>
> /* do sequencing checks */
>
> - if (krb5_get_seq_num(ctx->seq, ptr + 14, ptr + 6, &direction, &seqnum))
> + if (krb5_get_seq_num(ctx->seq, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8, &direction, &seqnum))
> return GSS_S_FAILURE;
>
> if ((ctx->initiate && direction != 0xff) ||
> diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
> index b00b1b4..283cb25 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
> @@ -122,7 +122,7 @@ gss_wrap_kerberos(struct gss_ctx *ctx, int offset,
> char cksumdata[16];
> struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata};
> int blocksize = 0, plainlen;
> - unsigned char *ptr, *krb5_hdr, *msg_start;
> + unsigned char *ptr, *msg_start;
> s32 now;
> int headlen;
> struct page **tmp_pages;
> @@ -149,26 +149,26 @@ gss_wrap_kerberos(struct gss_ctx *ctx, int offset,
> buf->len += headlen;
> BUG_ON((buf->len - offset - headlen) % blocksize);
>
> - g_make_token_header(&kctx->mech_used, 24 + plainlen, &ptr);
> + g_make_token_header(&kctx->mech_used,
> + GSS_KRB5_TOK_HDR_LEN + 8 + plainlen, &ptr);
>
>
> - *ptr++ = (unsigned char) ((KG_TOK_WRAP_MSG>>8)&0xff);
> - *ptr++ = (unsigned char) (KG_TOK_WRAP_MSG&0xff);
> + /* ptr now at header described in rfc 1964, section 1.2.1: */
> + ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff);
> + ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff);
>
> - /* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */
> - krb5_hdr = ptr - 2;
> - msg_start = krb5_hdr + 24;
> + msg_start = ptr + 24;
>
> - *(__be16 *)(krb5_hdr + 2) = htons(SGN_ALG_DES_MAC_MD5);
> - memset(krb5_hdr + 4, 0xff, 4);
> - *(__be16 *)(krb5_hdr + 4) = htons(SEAL_ALG_DES);
> + *(__be16 *)(ptr + 2) = htons(SGN_ALG_DES_MAC_MD5);
> + memset(ptr + 4, 0xff, 4);
> + *(__be16 *)(ptr + 4) = htons(SEAL_ALG_DES);
>
> make_confounder(msg_start, blocksize);
>
> /* XXXJBF: UGH!: */
> tmp_pages = buf->pages;
> buf->pages = pages;
> - if (make_checksum("md5", krb5_hdr, 8, buf,
> + if (make_checksum("md5", ptr, 8, buf,
> offset + headlen - blocksize, &md5cksum))
> return GSS_S_FAILURE;
> buf->pages = tmp_pages;
> @@ -176,7 +176,7 @@ gss_wrap_kerberos(struct gss_ctx *ctx, int offset,
> if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
> md5cksum.data, md5cksum.len))
> return GSS_S_FAILURE;
> - memcpy(krb5_hdr + 16, md5cksum.data + md5cksum.len - 8, 8);
> + memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data + md5cksum.len - 8, 8);
>
> spin_lock(&krb5_seq_lock);
> seq_send = kctx->seq_send++;
> @@ -185,7 +185,7 @@ gss_wrap_kerberos(struct gss_ctx *ctx, int offset,
> /* XXX would probably be more efficient to compute checksum
> * and encrypt at the same time: */
> if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff,
> - seq_send, krb5_hdr + 16, krb5_hdr + 8)))
> + seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8)))
> return GSS_S_FAILURE;
>
> if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize,
> @@ -219,38 +219,38 @@ gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf)
> buf->len - offset))
> return GSS_S_DEFECTIVE_TOKEN;
>
> - if ((*ptr++ != ((KG_TOK_WRAP_MSG>>8)&0xff)) ||
> - (*ptr++ != (KG_TOK_WRAP_MSG &0xff)) )
> + if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
> + (ptr[1] != (KG_TOK_WRAP_MSG & 0xff)))
> return GSS_S_DEFECTIVE_TOKEN;
>
> /* XXX sanity-check bodysize?? */
>
> /* get the sign and seal algorithms */
>
> - signalg = ptr[0] + (ptr[1] << 8);
> + signalg = ptr[2] + (ptr[3] << 8);
> if (signalg != SGN_ALG_DES_MAC_MD5)
> return GSS_S_DEFECTIVE_TOKEN;
>
> - sealalg = ptr[2] + (ptr[3] << 8);
> + sealalg = ptr[4] + (ptr[5] << 8);
> if (sealalg != SEAL_ALG_DES)
> return GSS_S_DEFECTIVE_TOKEN;
>
> - if ((ptr[4] != 0xff) || (ptr[5] != 0xff))
> + if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
> return GSS_S_DEFECTIVE_TOKEN;
>
> if (gss_decrypt_xdr_buf(kctx->enc, buf,
> - ptr + 22 - (unsigned char *)buf->head[0].iov_base))
> + ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base))
> return GSS_S_DEFECTIVE_TOKEN;
>
> - if (make_checksum("md5", ptr - 2, 8, buf,
> - ptr + 22 - (unsigned char *)buf->head[0].iov_base, &md5cksum))
> + if (make_checksum("md5", ptr, 8, buf,
> + ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base, &md5cksum))
> return GSS_S_FAILURE;
>
> if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
> md5cksum.data, md5cksum.len))
> return GSS_S_FAILURE;
>
> - if (memcmp(md5cksum.data + 8, ptr + 14, 8))
> + if (memcmp(md5cksum.data + 8, ptr + GSS_KRB5_TOK_HDR_LEN, 8))
> return GSS_S_BAD_SIG;
>
> /* it got through unscathed. Make sure the context is unexpired */
> @@ -262,8 +262,8 @@ gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf)
>
> /* do sequencing checks */
>
> - if (krb5_get_seq_num(kctx->seq, ptr + 14, ptr + 6, &direction,
> - &seqnum))
> + if (krb5_get_seq_num(kctx->seq, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8,
> + &direction, &seqnum))
> return GSS_S_BAD_SIG;
>
> if ((kctx->initiate && direction != 0xff) ||
> @@ -274,7 +274,7 @@ gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf)
> * better to copy and encrypt at the same time. */
>
> blocksize = crypto_blkcipher_blocksize(kctx->enc);
> - data_start = ptr + 22 + blocksize;
> + data_start = ptr + GSS_KRB5_TOK_HDR_LEN + 8 + blocksize;
> orig_start = buf->head[0].iov_base + offset;
> data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
> memmove(orig_start, data_start, data_len);
>