[1/4] smb: client: introduce av_for_each_entry() helper

Commit Message

Paulo Alcantara Jan. 3, 2025, 10:28 p.m. UTC

Use new helper in find_domain_name() and find_timestamp() to avoid
duplicating code.

Signed-off-by: Paulo Alcantara (Red Hat) <[e-mail]>
---
 fs/smb/client/cifsencrypt.c | 123 ++++++++++++++++--------------------
 fs/smb/client/cifspdu.h     |   2 +-
 2 files changed, 54 insertions(+), 71 deletions(-)

Patch

diff --git a/fs/smb/client/cifsencrypt.c b/fs/smb/client/cifsencrypt.c
index 7a43daacc815..981897ec4dcd 100644
--- a/fs/smb/client/cifsencrypt.c
+++ b/fs/smb/client/cifsencrypt.c
@@ -315,6 +315,39 @@  build_avpair_blob(struct cifs_ses *ses, const struct nls_table *nls_cp)
 	return 0;
 }
 
+#define AV_TYPE(av)		(le16_to_cpu(av->type))
+#define AV_LEN(av)		(le16_to_cpu(av->length))
+#define AV_DATA_PTR(av)	((void *)av->data)
+
+#define av_for_each_entry(ses, av) \
+	for (av = NULL; (av = find_next_av(ses, av));)
+
+static struct ntlmssp2_name *find_next_av(struct cifs_ses *ses,
+					  struct ntlmssp2_name *av)
+{
+	u16 len;
+	u8 *end;
+
+	end = (u8 *)ses->auth_key.response + ses->auth_key.len;
+	if (!av) {
+		if (unlikely(!ses->auth_key.response || !ses->auth_key.len))
+			return NULL;
+		av = (void *)ses->auth_key.response;
+	} else {
+		av = (void *)((u8 *)av + sizeof(*av) + AV_LEN(av));
+	}
+
+	if ((u8 *)av + sizeof(*av) > end)
+		return NULL;
+
+	len = AV_LEN(av);
+	if (AV_TYPE(av) == NTLMSSP_AV_EOL)
+		return NULL;
+	if (!len || (u8 *)av + sizeof(*av) + len > end)
+		return NULL;
+	return av;
+}
+
 /* Server has provided av pairs/target info in the type 2 challenge
  * packet and we have plucked it and stored within smb session.
  * We parse that blob here to find netbios domain name to be used
@@ -325,49 +358,23 @@  build_avpair_blob(struct cifs_ses *ses, const struct nls_table *nls_cp)
  * may not fail against other (those who are not very particular
  * about target string i.e. for some, just user name might suffice.
  */
-static int
-find_domain_name(struct cifs_ses *ses, const struct nls_table *nls_cp)
+static int find_domain_name(struct cifs_ses *ses)
 {
-	unsigned int attrsize;
-	unsigned int type;
-	unsigned int onesize = sizeof(struct ntlmssp2_name);
-	unsigned char *blobptr;
-	unsigned char *blobend;
-	struct ntlmssp2_name *attrptr;
+	const struct nls_table *nlsc = ses->local_nls;
+	struct ntlmssp2_name *av;
+	u16 len;
 
-	if (!ses->auth_key.len || !ses->auth_key.response)
-		return 0;
-
-	blobptr = ses->auth_key.response;
-	blobend = blobptr + ses->auth_key.len;
-
-	while (blobptr + onesize < blobend) {
-		attrptr = (struct ntlmssp2_name *) blobptr;
-		type = le16_to_cpu(attrptr->type);
-		if (type == NTLMSSP_AV_EOL)
-			break;
-		blobptr += 2; /* advance attr type */
-		attrsize = le16_to_cpu(attrptr->length);
-		blobptr += 2; /* advance attr size */
-		if (blobptr + attrsize > blobend)
-			break;
-		if (type == NTLMSSP_AV_NB_DOMAIN_NAME) {
-			if (!attrsize || attrsize >= CIFS_MAX_DOMAINNAME_LEN)
-				break;
-			if (!ses->domainName) {
-				ses->domainName =
-					kmalloc(attrsize + 1, GFP_KERNEL);
-				if (!ses->domainName)
-						return -ENOMEM;
-				cifs_from_utf16(ses->domainName,
-					(__le16 *)blobptr, attrsize, attrsize,
-					nls_cp, NO_MAP_UNI_RSVD);
-				break;
-			}
+	av_for_each_entry(ses, av) {
+		len = AV_LEN(av);
+		if (AV_TYPE(av) == NTLMSSP_AV_NB_DOMAIN_NAME &&
+		    len < CIFS_MAX_DOMAINNAME_LEN && !ses->domainName) {
+			ses->domainName = kmalloc(len + 1, GFP_KERNEL);
+			if (!ses->domainName)
+				return -ENOMEM;
+			cifs_from_utf16(ses->domainName, AV_DATA_PTR(av),
+					len, len, nlsc, NO_MAP_UNI_RSVD);
 		}
-		blobptr += attrsize; /* advance attr  value */
 	}
-
 	return 0;
 }
 
@@ -377,40 +384,16 @@  find_domain_name(struct cifs_ses *ses, const struct nls_table *nls_cp)
  * as part of ntlmv2 authentication (or local current time as
  * default in case of failure)
  */
-static __le64
-find_timestamp(struct cifs_ses *ses)
+static __le64 find_timestamp(struct cifs_ses *ses)
 {
-	unsigned int attrsize;
-	unsigned int type;
-	unsigned int onesize = sizeof(struct ntlmssp2_name);
-	unsigned char *blobptr;
-	unsigned char *blobend;
-	struct ntlmssp2_name *attrptr;
+	struct ntlmssp2_name *av;
 	struct timespec64 ts;
 
-	if (!ses->auth_key.len || !ses->auth_key.response)
-		return 0;
-
-	blobptr = ses->auth_key.response;
-	blobend = blobptr + ses->auth_key.len;
-
-	while (blobptr + onesize < blobend) {
-		attrptr = (struct ntlmssp2_name *) blobptr;
-		type = le16_to_cpu(attrptr->type);
-		if (type == NTLMSSP_AV_EOL)
-			break;
-		blobptr += 2; /* advance attr type */
-		attrsize = le16_to_cpu(attrptr->length);
-		blobptr += 2; /* advance attr size */
-		if (blobptr + attrsize > blobend)
-			break;
-		if (type == NTLMSSP_AV_TIMESTAMP) {
-			if (attrsize == sizeof(u64))
-				return *((__le64 *)blobptr);
-		}
-		blobptr += attrsize; /* advance attr value */
+	av_for_each_entry(ses, av) {
+		if (AV_TYPE(av) == NTLMSSP_AV_TIMESTAMP &&
+		    AV_LEN(av) == sizeof(u64))
+			return *((__le64 *)AV_DATA_PTR(av));
 	}
-
 	ktime_get_real_ts64(&ts);
 	return cpu_to_le64(cifs_UnixTimeToNT(ts));
 }
@@ -563,7 +546,7 @@  setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
 	if (ses->server->negflavor == CIFS_NEGFLAVOR_EXTENDED) {
 		if (!ses->domainName) {
 			if (ses->domainAuto) {
-				rc = find_domain_name(ses, nls_cp);
+				rc = find_domain_name(ses);
 				if (rc) {
 					cifs_dbg(VFS, "error %d finding domain name\n",
 						 rc);
diff --git a/fs/smb/client/cifspdu.h b/fs/smb/client/cifspdu.h
index ee78bb6741d6..17202754e6d0 100644
--- a/fs/smb/client/cifspdu.h
+++ b/fs/smb/client/cifspdu.h
@@ -649,7 +649,7 @@  typedef union smb_com_session_setup_andx {
 struct ntlmssp2_name {
 	__le16 type;
 	__le16 length;
-/*	char   name[length]; */
+	__u8 data[];
 } __attribute__((packed));
 
 struct ntlmv2_resp {