[PATCH v2 4/4] ksmbd: add buffer validation for SMB2_CREATE_CONTEXT

[Namjae Jeon <linkinjeon@kernel.org>]

From: Hyunchul Lee <hyc.lee@gmail.com>

Add buffer validation for SMB2_CREATE_CONTEXT.

Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Ralph Böhme <slow@samba.org>
Cc: Steve French <smfrench@gmail.com>
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/ksmbd/oplock.c  | 35 +++++++++++++++++++++++++----------
 fs/ksmbd/smb2pdu.c | 25 ++++++++++++++++++++++++-
 fs/ksmbd/smbacl.c  |  9 ++++++++-
 3 files changed, 57 insertions(+), 12 deletions(-)

diff --git a/fs/ksmbd/oplock.c b/fs/ksmbd/oplock.c
index 16b6236d1bd2..3fd2713f2282 100644
--- a/fs/ksmbd/oplock.c
+++ b/fs/ksmbd/oplock.c
@@ -1451,26 +1451,41 @@ struct lease_ctx_info *parse_lease_state(void *open_req)
  */
 struct create_context *smb2_find_context_vals(void *open_req, const char *tag)
 {
-	char *data_offset;
+	struct smb2_create_req *req = (struct smb2_create_req *)open_req;
 	struct create_context *cc;
-	unsigned int next = 0;
+	char *data_offset, *data_end;
 	char *name;
-	struct smb2_create_req *req = (struct smb2_create_req *)open_req;
+	unsigned int next = 0;
+	unsigned int name_off, name_len, value_off, value_len;
 
 	data_offset = (char *)req + 4 + le32_to_cpu(req->CreateContextsOffset);
+	data_end = data_offset + le32_to_cpu(req->CreateContextsLength);
 	cc = (struct create_context *)data_offset;
 	do {
-		int val;
-
 		cc = (struct create_context *)((char *)cc + next);
-		name = le16_to_cpu(cc->NameOffset) + (char *)cc;
-		val = le16_to_cpu(cc->NameLength);
-		if (val < 4)
+		if ((char *)cc + offsetof(struct create_context, Buffer) >
+		    data_end)
 			return ERR_PTR(-EINVAL);
 
-		if (memcmp(name, tag, val) == 0)
-			return cc;
 		next = le32_to_cpu(cc->Next);
+		name_off = le16_to_cpu(cc->NameOffset);
+		name_len = le16_to_cpu(cc->NameLength);
+		value_off = le16_to_cpu(cc->DataOffset);
+		value_len = le32_to_cpu(cc->DataLength);
+
+		if ((char *)cc + name_off + name_len > data_end ||
+		    (value_len && (char *)cc + value_off + value_len > data_end))
+			return ERR_PTR(-EINVAL);
+		else if (next && (next < name_off + name_len ||
+			 (value_len && next < value_off + value_len)))
+			return ERR_PTR(-EINVAL);
+
+		name = (char *)cc + name_off;
+		if (name_len < 4)
+			return ERR_PTR(-EINVAL);
+
+		if (memcmp(name, tag, name_len) == 0)
+			return cc;
 	} while (next != 0);
 
 	return NULL;
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 117cf242d9b8..6d57827320e3 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -2393,6 +2393,10 @@ static int smb2_create_sd_buffer(struct ksmbd_work *work,
 	ksmbd_debug(SMB,
 		    "Set ACLs using SMB2_CREATE_SD_BUFFER context\n");
 	sd_buf = (struct create_sd_buf_req *)context;
+	if (le16_to_cpu(context->DataOffset) +
+	    le32_to_cpu(context->DataLength) <
+	    sizeof(struct create_sd_buf_req))
+		return -EINVAL;
 	return set_info_sec(work->conn, work->tcon, path, &sd_buf->ntsd,
 			    le32_to_cpu(sd_buf->ccontext.DataLength), true);
 }
@@ -2593,6 +2597,12 @@ int smb2_open(struct ksmbd_work *work)
 			goto err_out1;
 		} else if (context) {
 			ea_buf = (struct create_ea_buf_req *)context;
+			if (le16_to_cpu(context->DataOffset) +
+			    le32_to_cpu(context->DataLength) <
+			    sizeof(struct create_ea_buf_req)) {
+				rc = -EINVAL;
+				goto err_out1;
+			}
 			if (req->CreateOptions & FILE_NO_EA_KNOWLEDGE_LE) {
 				rsp->hdr.Status = STATUS_ACCESS_DENIED;
 				rc = -EACCES;
@@ -2631,6 +2641,12 @@ int smb2_open(struct ksmbd_work *work)
 			} else if (context) {
 				struct create_posix *posix =
 					(struct create_posix *)context;
+				if (le16_to_cpu(context->DataOffset) +
+				    le32_to_cpu(context->DataLength) <
+				    sizeof(struct create_posix)) {
+					rc = -EINVAL;
+					goto err_out1;
+				}
 				ksmbd_debug(SMB, "get posix context\n");
 
 				posix_mode = le32_to_cpu(posix->Mode);
@@ -3037,9 +3053,16 @@ int smb2_open(struct ksmbd_work *work)
 			rc = PTR_ERR(az_req);
 			goto err_out;
 		} else if (az_req) {
-			loff_t alloc_size = le64_to_cpu(az_req->AllocationSize);
+			loff_t alloc_size;
 			int err;
 
+			if (le16_to_cpu(az_req->ccontext.DataOffset) +
+			    le32_to_cpu(az_req->ccontext.DataLength) <
+			    sizeof(struct create_alloc_size_req)) {
+				rc = -EINVAL;
+				goto err_out;
+			}
+			alloc_size = le64_to_cpu(az_req->AllocationSize);
 			ksmbd_debug(SMB,
 				    "request smb2 create allocate size : %llu\n",
 				    alloc_size);
diff --git a/fs/ksmbd/smbacl.c b/fs/ksmbd/smbacl.c
index 0a95cdec8c80..f67567e1e178 100644
--- a/fs/ksmbd/smbacl.c
+++ b/fs/ksmbd/smbacl.c
@@ -392,7 +392,7 @@ static void parse_dacl(struct user_namespace *user_ns,
 		return;
 
 	/* validate that we do not go past end of acl */
-	if (end_of_acl <= (char *)pdacl ||
+	if (end_of_acl < (char *)pdacl + sizeof(struct smb_acl) ||
 	    end_of_acl < (char *)pdacl + le16_to_cpu(pdacl->size)) {
 		pr_err("ACL too small to parse DACL\n");
 		return;
@@ -434,6 +434,10 @@ static void parse_dacl(struct user_namespace *user_ns,
 		ppace[i] = (struct smb_ace *)(acl_base + acl_size);
 		acl_base = (char *)ppace[i];
 		acl_size = le16_to_cpu(ppace[i]->size);
+
+		if (acl_base + acl_size > end_of_acl)
+			break;
+
 		ppace[i]->access_req =
 			smb_map_generic_desired_access(ppace[i]->access_req);
 
@@ -807,6 +811,9 @@ int parse_sec_desc(struct user_namespace *user_ns, struct smb_ntsd *pntsd,
 	if (!pntsd)
 		return -EIO;
 
+	if (acl_len < sizeof(struct smb_ntsd))
+		return -EINVAL;
+
 	owner_sid_ptr = (struct smb_sid *)((char *)pntsd +
 			le32_to_cpu(pntsd->osidoffset));
 	group_sid_ptr = (struct smb_sid *)((char *)pntsd +
-- 
2.25.1