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

["J. Bruce Fields" <bfields@fieldses.org>]

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 <kwc@citi.umich.edu>
> ---
> 
>  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);
>