1 files changed, 95 insertions, 0 deletions
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index ab31d6f54221..08d6a130e512 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -4302,6 +4302,101 @@ SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
 	return rc;
 }
 
+static int posix_info_sid_size(const void *beg, const void *end)
+{
+	size_t subauth;
+	int total;
+
+	if (beg + 1 > end)
+		return -1;
+
+	subauth = *(u8 *)(beg+1);
+	if (subauth < 1 || subauth > 15)
+		return -1;
+
+	total = 1 + 1 + 6 + 4*subauth;
+	if (beg + total > end)
+		return -1;
+
+	return total;
+}
+
+int posix_info_parse(const void *beg, const void *end,
+		     struct smb2_posix_info_parsed *out)
+
+{
+	int total_len = 0;
+	int sid_len;
+	int name_len;
+	const void *owner_sid;
+	const void *group_sid;
+	const void *name;
+
+	/* if no end bound given, assume payload to be correct */
+	if (!end) {
+		const struct smb2_posix_info *p = beg;
+
+		end = beg + le32_to_cpu(p->NextEntryOffset);
+		/* last element will have a 0 offset, pick a sensible bound */
+		if (end == beg)
+			end += 0xFFFF;
+	}
+
+	/* check base buf */
+	if (beg + sizeof(struct smb2_posix_info) > end)
+		return -1;
+	total_len = sizeof(struct smb2_posix_info);
+
+	/* check owner sid */
+	owner_sid = beg + total_len;
+	sid_len = posix_info_sid_size(owner_sid, end);
+	if (sid_len < 0)
+		return -1;
+	total_len += sid_len;
+
+	/* check group sid */
+	group_sid = beg + total_len;
+	sid_len = posix_info_sid_size(group_sid, end);
+	if (sid_len < 0)
+		return -1;
+	total_len += sid_len;
+
+	/* check name len */
+	if (beg + total_len + 4 > end)
+		return -1;
+	name_len = le32_to_cpu(*(__le32 *)(beg + total_len));
+	if (name_len < 1 || name_len > 0xFFFF)
+		return -1;
+	total_len += 4;
+
+	/* check name */
+	name = beg + total_len;
+	if (name + name_len > end)
+		return -1;
+	total_len += name_len;
+
+	if (out) {
+		out->base = beg;
+		out->size = total_len;
+		out->name_len = name_len;
+		out->name = name;
+		memcpy(&out->owner, owner_sid,
+		       posix_info_sid_size(owner_sid, end));
+		memcpy(&out->group, group_sid,
+		       posix_info_sid_size(group_sid, end));
+	}
+	return total_len;
+}
+
+static int posix_info_extra_size(const void *beg, const void *end)
+{
+	int len = posix_info_parse(beg, end, NULL);
+
+	if (len < 0)
+		return -1;
+	return len - sizeof(struct smb2_posix_info);
+}
+
 static unsigned int
 num_entries(char *bufstart, char *end_of_buf, char **lastentry, size_t size)
 {