smb: client: improve compound padding in encryption

After commit f7f291e ("cifs: fix oops during encryption"), the
encryption layer can handle vmalloc'd buffers as well as kmalloc'd
buffers, so there is no need to inefficiently squash request iovs
into a single one to handle padding in compound requests.

Cc: David Howells <[email protected]>
Signed-off-by: Paulo Alcantara (Red Hat) <[email protected]>
Signed-off-by: Steve French <[email protected]>

Author: Paulo Alcantara

fs/smb/client/cifsglob.h

@@ -2230,7 +2230,7 @@ static inline int cifs_get_num_sgs(const struct smb_rqst *rqst,
 			struct kvec *iov = &rqst[i].rq_iov[j];
 
 			addr = (unsigned long)iov->iov_base + skip;
-			if (unlikely(is_vmalloc_addr((void *)addr))) {
+			if (is_vmalloc_or_module_addr((void *)addr)) {
 				len = iov->iov_len - skip;
 				nents += DIV_ROUND_UP(offset_in_page(addr) + len,
 						      PAGE_SIZE);
@@ -2257,7 +2257,7 @@ static inline void cifs_sg_set_buf(struct sg_table *sgtable,
 	unsigned int off = offset_in_page(addr);
 
 	addr &= PAGE_MASK;
-	if (unlikely(is_vmalloc_addr((void *)addr))) {
+	if (is_vmalloc_or_module_addr((void *)addr)) {
 		do {
 			unsigned int len = min_t(unsigned int, buflen, PAGE_SIZE - off);
 

fs/smb/client/smb2ops.c

@@ -2606,7 +2606,7 @@ smb2_set_next_command(struct cifs_tcon *tcon, struct smb_rqst *rqst)
 	struct cifs_ses *ses = tcon->ses;
 	struct TCP_Server_Info *server = ses->server;
 	unsigned long len = smb_rqst_len(server, rqst);
-	int i, num_padding;
+	int num_padding;
 
 	shdr = (struct smb2_hdr *)(rqst->rq_iov[0].iov_base);
 	if (shdr == NULL) {
@@ -2615,44 +2615,13 @@ smb2_set_next_command(struct cifs_tcon *tcon, struct smb_rqst *rqst)
 	}
 
 	/* SMB headers in a compound are 8 byte aligned. */
-
-	/* No padding needed */
-	if (!(len & 7))
-		goto finished;
-
-	num_padding = 8 - (len & 7);
-	if (!smb3_encryption_required(tcon)) {
-		/*
-		 * If we do not have encryption then we can just add an extra
-		 * iov for the padding.
-		 */
+	if (!IS_ALIGNED(len, 8)) {
+		num_padding = 8 - (len & 7);
 		rqst->rq_iov[rqst->rq_nvec].iov_base = smb2_padding;
 		rqst->rq_iov[rqst->rq_nvec].iov_len = num_padding;
 		rqst->rq_nvec++;
 		len += num_padding;
-	} else {
-		/*
-		 * We can not add a small padding iov for the encryption case
-		 * because the encryption framework can not handle the padding
-		 * iovs.
-		 * We have to flatten this into a single buffer and add
-		 * the padding to it.
-		 */
-		for (i = 1; i < rqst->rq_nvec; i++) {
-			memcpy(rqst->rq_iov[0].iov_base +
-			       rqst->rq_iov[0].iov_len,
-			       rqst->rq_iov[i].iov_base,
-			       rqst->rq_iov[i].iov_len);
-			rqst->rq_iov[0].iov_len += rqst->rq_iov[i].iov_len;
-		}
-		memset(rqst->rq_iov[0].iov_base + rqst->rq_iov[0].iov_len,
-		       0, num_padding);
-		rqst->rq_iov[0].iov_len += num_padding;
-		len += num_padding;
-		rqst->rq_nvec = 1;
 	}
-
- finished:
 	shdr->NextCommand = cpu_to_le32(len);
 }
 

fs/smb/client/transport.c

@@ -418,19 +418,16 @@ __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 	return rc;
 }
 
-struct send_req_vars {
-	struct smb2_transform_hdr tr_hdr;
-	struct smb_rqst rqst[MAX_COMPOUND];
-	struct kvec iov;
-};
-
 static int
 smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 	      struct smb_rqst *rqst, int flags)
 {
-	struct send_req_vars *vars;
-	struct smb_rqst *cur_rqst;
-	struct kvec *iov;
+	struct smb2_transform_hdr tr_hdr;
+	struct smb_rqst new_rqst[MAX_COMPOUND] = {};
+	struct kvec iov = {
+		.iov_base = &tr_hdr,
+		.iov_len = sizeof(tr_hdr),
+	};
 	int rc;
 
 	if (flags & CIFS_COMPRESS_REQ)
@@ -447,26 +444,15 @@ smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 		return -EIO;
 	}
 
-	vars = kzalloc(sizeof(*vars), GFP_NOFS);
-	if (!vars)
-		return -ENOMEM;
-	cur_rqst = vars->rqst;
-	iov = &vars->iov;
-
-	iov->iov_base = &vars->tr_hdr;
-	iov->iov_len = sizeof(vars->tr_hdr);
-	cur_rqst[0].rq_iov = iov;
-	cur_rqst[0].rq_nvec = 1;
+	new_rqst[0].rq_iov = &iov;
+	new_rqst[0].rq_nvec = 1;
 
 	rc = server->ops->init_transform_rq(server, num_rqst + 1,
-					    &cur_rqst[0], rqst);
-	if (rc)
-		goto out;
-
-	rc = __smb_send_rqst(server, num_rqst + 1, &cur_rqst[0]);
-	smb3_free_compound_rqst(num_rqst, &cur_rqst[1]);
-out:
-	kfree(vars);
+					    new_rqst, rqst);
+	if (!rc) {
+		rc = __smb_send_rqst(server, num_rqst + 1, new_rqst);
+		smb3_free_compound_rqst(num_rqst, &new_rqst[1]);
+	}
 	return rc;
 }