SUNRPC: Add "@len" parameter to gss_unwrap()

Refactor: This is a pre-requisite to fixing the client-side ralign
computation in gss_unwrap_resp_priv().

The length value is passed in explicitly rather that as the value
of buf->len. This will subsequently allow gss_unwrap_kerberos_v1()
to compute a slack and align value, instead of computing it in
gss_unwrap_resp_priv().

Fixes: 35e77d21 ("SUNRPC: Add rpc_auth::au_ralign field")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

include/linux/sunrpc/gss_api.h

@@ -66,6 +66,7 @@ u32 gss_wrap(
 u32 gss_unwrap(
 		struct gss_ctx		*ctx_id,
 		int			offset,
+		int			len,
 		struct xdr_buf		*inbuf);
 u32 gss_delete_sec_context(
 		struct gss_ctx		**ctx_id);
@@ -126,6 +127,7 @@ struct gss_api_ops {
 	u32 (*gss_unwrap)(
 			struct gss_ctx		*ctx_id,
 			int			offset,
+			int			len,
 			struct xdr_buf		*buf);
 	void (*gss_delete_sec_context)(
 			void			*internal_ctx_id);

include/linux/sunrpc/gss_krb5.h

@@ -83,7 +83,7 @@ struct gss_krb5_enctype {
 	u32 (*encrypt_v2) (struct krb5_ctx *kctx, u32 offset,
 			   struct xdr_buf *buf,
 			   struct page **pages); /* v2 encryption function */
-	u32 (*decrypt_v2) (struct krb5_ctx *kctx, u32 offset,
+	u32 (*decrypt_v2) (struct krb5_ctx *kctx, u32 offset, u32 len,
 			   struct xdr_buf *buf, u32 *headskip,
 			   u32 *tailskip);	/* v2 decryption function */
 };
@@ -255,7 +255,7 @@ gss_wrap_kerberos(struct gss_ctx *ctx_id, int offset,
 		struct xdr_buf *outbuf, struct page **pages);
 
 u32
-gss_unwrap_kerberos(struct gss_ctx *ctx_id, int offset,
+gss_unwrap_kerberos(struct gss_ctx *ctx_id, int offset, int len,
 		struct xdr_buf *buf);
 
 
@@ -312,7 +312,7 @@ gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
 		     struct page **pages);
 
 u32
-gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset,
+gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
 		     struct xdr_buf *buf, u32 *plainoffset,
 		     u32 *plainlen);
 

net/sunrpc/auth_gss/auth_gss.c

@@ -2043,9 +2043,9 @@ gss_unwrap_resp_priv(struct rpc_task *task, struct rpc_cred *cred,
 	offset = (u8 *)(p) - (u8 *)head->iov_base;
 	if (offset + opaque_len > rcv_buf->len)
 		goto unwrap_failed;
-	rcv_buf->len = offset + opaque_len;
 
-	maj_stat = gss_unwrap(ctx->gc_gss_ctx, offset, rcv_buf);
+	maj_stat = gss_unwrap(ctx->gc_gss_ctx, offset,
+			      offset + opaque_len, rcv_buf);
 	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
 		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
 	if (maj_stat != GSS_S_COMPLETE)

net/sunrpc/auth_gss/gss_krb5_crypto.c

@@ -851,8 +851,8 @@ gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
 }
 
 u32
-gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
-		     u32 *headskip, u32 *tailskip)
+gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
+		     struct xdr_buf *buf, u32 *headskip, u32 *tailskip)
 {
 	struct xdr_buf subbuf;
 	u32 ret = 0;
@@ -881,7 +881,7 @@ gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
 
 	/* create a segment skipping the header and leaving out the checksum */
 	xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
-				    (buf->len - offset - GSS_KRB5_TOK_HDR_LEN -
+				    (len - offset - GSS_KRB5_TOK_HDR_LEN -
 				     kctx->gk5e->cksumlength));
 
 	nblocks = (subbuf.len + blocksize - 1) / blocksize;
@@ -926,7 +926,7 @@ gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
 		goto out_err;
 
 	/* Get the packet's hmac value */
-	ret = read_bytes_from_xdr_buf(buf, buf->len - kctx->gk5e->cksumlength,
+	ret = read_bytes_from_xdr_buf(buf, len - kctx->gk5e->cksumlength,
 				      pkt_hmac, kctx->gk5e->cksumlength);
 	if (ret)
 		goto out_err;

net/sunrpc/auth_gss/gss_krb5_wrap.c

@@ -261,7 +261,8 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
 }
 
 static u32
-gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
+gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len,
+		       struct xdr_buf *buf)
 {
 	int			signalg;
 	int			sealalg;
@@ -284,7 +285,7 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
 
 	ptr = (u8 *)buf->head[0].iov_base + offset;
 	if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr,
-					buf->len - offset))
+					len - offset))
 		return GSS_S_DEFECTIVE_TOKEN;
 
 	if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
@@ -324,6 +325,7 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
 	    (!kctx->initiate && direction != 0))
 		return GSS_S_BAD_SIG;
 
+	buf->len = len;
 	if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
 		struct crypto_sync_skcipher *cipher;
 		int err;
@@ -376,7 +378,7 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
 	data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
 	memmove(orig_start, data_start, data_len);
 	buf->head[0].iov_len -= (data_start - orig_start);
-	buf->len -= (data_start - orig_start);
+	buf->len = len - (data_start - orig_start);
 
 	if (gss_krb5_remove_padding(buf, blocksize))
 		return GSS_S_DEFECTIVE_TOKEN;
@@ -486,7 +488,8 @@ gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset,
 }
 
 static u32
-gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
+gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len,
+		       struct xdr_buf *buf)
 {
 	time64_t	now;
 	u8		*ptr;
@@ -532,7 +535,7 @@ gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
 	if (rrc != 0)
 		rotate_left(offset + 16, buf, rrc);
 
-	err = (*kctx->gk5e->decrypt_v2)(kctx, offset, buf,
+	err = (*kctx->gk5e->decrypt_v2)(kctx, offset, len, buf,
 					&headskip, &tailskip);
 	if (err)
 		return GSS_S_FAILURE;
@@ -542,7 +545,7 @@ gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
 	 * it against the original
 	 */
 	err = read_bytes_from_xdr_buf(buf,
-				buf->len - GSS_KRB5_TOK_HDR_LEN - tailskip,
+				len - GSS_KRB5_TOK_HDR_LEN - tailskip,
 				decrypted_hdr, GSS_KRB5_TOK_HDR_LEN);
 	if (err) {
 		dprintk("%s: error %u getting decrypted_hdr\n", __func__, err);
@@ -568,14 +571,14 @@ gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
 	 * Note that buf->head[0].iov_len may indicate the available
 	 * head buffer space rather than that actually occupied.
 	 */
-	movelen = min_t(unsigned int, buf->head[0].iov_len, buf->len);
+	movelen = min_t(unsigned int, buf->head[0].iov_len, len);
 	movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;
 	if (offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >
 	    buf->head[0].iov_len)
 		return GSS_S_FAILURE;
 	memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen);
 	buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;
-	buf->len -= GSS_KRB5_TOK_HDR_LEN + headskip;
+	buf->len = len - GSS_KRB5_TOK_HDR_LEN + headskip;
 
 	/* Trim off the trailing "extra count" and checksum blob */
 	buf->len -= ec + GSS_KRB5_TOK_HDR_LEN + tailskip;
@@ -603,7 +606,8 @@ gss_wrap_kerberos(struct gss_ctx *gctx, int offset,
 }
 
 u32
-gss_unwrap_kerberos(struct gss_ctx *gctx, int offset, struct xdr_buf *buf)
+gss_unwrap_kerberos(struct gss_ctx *gctx, int offset,
+		    int len, struct xdr_buf *buf)
 {
 	struct krb5_ctx	*kctx = gctx->internal_ctx_id;
 
@@ -613,9 +617,9 @@ gss_unwrap_kerberos(struct gss_ctx *gctx, int offset, struct xdr_buf *buf)
 	case ENCTYPE_DES_CBC_RAW:
 	case ENCTYPE_DES3_CBC_RAW:
 	case ENCTYPE_ARCFOUR_HMAC:
-		return gss_unwrap_kerberos_v1(kctx, offset, buf);
+		return gss_unwrap_kerberos_v1(kctx, offset, len, buf);
 	case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
 	case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
-		return gss_unwrap_kerberos_v2(kctx, offset, buf);
+		return gss_unwrap_kerberos_v2(kctx, offset, len, buf);
 	}
 }

net/sunrpc/auth_gss/gss_mech_switch.c

@@ -411,10 +411,11 @@ gss_wrap(struct gss_ctx	*ctx_id,
 u32
 gss_unwrap(struct gss_ctx	*ctx_id,
 	   int			offset,
+	   int			len,
 	   struct xdr_buf	*buf)
 {
 	return ctx_id->mech_type->gm_ops
-		->gss_unwrap(ctx_id, offset, buf);
+		->gss_unwrap(ctx_id, offset, len, buf);
 }
 
 

net/sunrpc/auth_gss/svcauth_gss.c

@@ -934,7 +934,7 @@ static int
 unwrap_priv_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct gss_ctx *ctx)
 {
 	u32 priv_len, maj_stat;
-	int pad, saved_len, remaining_len, offset;
+	int pad, remaining_len, offset;
 
 	clear_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
 
@@ -954,12 +954,8 @@ unwrap_priv_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct gs
 	buf->len -= pad;
 	fix_priv_head(buf, pad);
 
-	/* Maybe it would be better to give gss_unwrap a length parameter: */
-	saved_len = buf->len;
-	buf->len = priv_len;
-	maj_stat = gss_unwrap(ctx, 0, buf);
+	maj_stat = gss_unwrap(ctx, 0, priv_len, buf);
 	pad = priv_len - buf->len;
-	buf->len = saved_len;
 	buf->len -= pad;
 	/* The upper layers assume the buffer is aligned on 4-byte boundaries.
 	 * In the krb5p case, at least, the data ends up offset, so we need to