1 files changed, 343 insertions, 0 deletions
diff --git a/fs/ksmbd/asn1.c b/fs/ksmbd/asn1.c
new file mode 100644
index 000000000000..b014f4638610
--- /dev/null
+++ b/fs/ksmbd/asn1.c
@@ -0,0 +1,343 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * The ASB.1/BER parsing code is derived from ip_nat_snmp_basic.c which was in
+ * turn derived from the gxsnmp package by Gregory McLean & Jochen Friedrich
+ *
+ * Copyright (c) 2000 RP Internet (www.rpi.net.au).
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/oid_registry.h>
+
+#include "glob.h"
+
+#include "asn1.h"
+#include "connection.h"
+#include "auth.h"
+#include "ksmbd_spnego_negtokeninit.asn1.h"
+#include "ksmbd_spnego_negtokentarg.asn1.h"
+
+#define SPNEGO_OID_LEN 7
+#define NTLMSSP_OID_LEN  10
+#define KRB5_OID_LEN  7
+#define KRB5U2U_OID_LEN  8
+#define MSKRB5_OID_LEN  7
+static unsigned long SPNEGO_OID[7] = { 1, 3, 6, 1, 5, 5, 2 };
+static unsigned long NTLMSSP_OID[10] = { 1, 3, 6, 1, 4, 1, 311, 2, 2, 10 };
+static unsigned long KRB5_OID[7] = { 1, 2, 840, 113554, 1, 2, 2 };
+static unsigned long KRB5U2U_OID[8] = { 1, 2, 840, 113554, 1, 2, 2, 3 };
+static unsigned long MSKRB5_OID[7] = { 1, 2, 840, 48018, 1, 2, 2 };
+
+static char NTLMSSP_OID_STR[NTLMSSP_OID_LEN] = { 0x2b, 0x06, 0x01, 0x04, 0x01,
+	0x82, 0x37, 0x02, 0x02, 0x0a };
+
+static bool
+asn1_subid_decode(const unsigned char **begin, const unsigned char *end,
+		  unsigned long *subid)
+{
+	const unsigned char *ptr = *begin;
+	unsigned char ch;
+
+	*subid = 0;
+
+	do {
+		if (ptr >= end)
+			return false;
+
+		ch = *ptr++;
+		*subid <<= 7;
+		*subid |= ch & 0x7F;
+	} while ((ch & 0x80) == 0x80);
+
+	*begin = ptr;
+	return true;
+}
+
+static bool asn1_oid_decode(const unsigned char *value, size_t vlen,
+			    unsigned long **oid, size_t *oidlen)
+{
+	const unsigned char *iptr = value, *end = value + vlen;
+	unsigned long *optr;
+	unsigned long subid;
+
+	vlen += 1;
+	if (vlen < 2 || vlen > UINT_MAX / sizeof(unsigned long))
+		goto fail_nullify;
+
+	*oid = kmalloc(vlen * sizeof(unsigned long), GFP_KERNEL);
+	if (!*oid)
+		return false;
+
+	optr = *oid;
+
+	if (!asn1_subid_decode(&iptr, end, &subid))
+		goto fail;
+
+	if (subid < 40) {
+		optr[0] = 0;
+		optr[1] = subid;
+	} else if (subid < 80) {
+		optr[0] = 1;
+		optr[1] = subid - 40;
+	} else {
+		optr[0] = 2;
+		optr[1] = subid - 80;
+	}
+
+	*oidlen = 2;
+	optr += 2;
+
+	while (iptr < end) {
+		if (++(*oidlen) > vlen)
+			goto fail;
+
+		if (!asn1_subid_decode(&iptr, end, optr++))
+			goto fail;
+	}
+	return true;
+
+fail:
+	kfree(*oid);
+fail_nullify:
+	*oid = NULL;
+	return false;
+}
+
+static bool oid_eq(unsigned long *oid1, unsigned int oid1len,
+		   unsigned long *oid2, unsigned int oid2len)
+{
+	if (oid1len != oid2len)
+		return false;
+
+	return memcmp(oid1, oid2, oid1len) == 0;
+}
+
+int
+ksmbd_decode_negTokenInit(unsigned char *security_blob, int length,
+			  struct ksmbd_conn *conn)
+{
+	return asn1_ber_decoder(&ksmbd_spnego_negtokeninit_decoder, conn,
+				security_blob, length);
+}
+
+int
+ksmbd_decode_negTokenTarg(unsigned char *security_blob, int length,
+			  struct ksmbd_conn *conn)
+{
+	return asn1_ber_decoder(&ksmbd_spnego_negtokentarg_decoder, conn,
+				security_blob, length);
+}
+
+static int compute_asn_hdr_len_bytes(int len)
+{
+	if (len > 0xFFFFFF)
+		return 4;
+	else if (len > 0xFFFF)
+		return 3;
+	else if (len > 0xFF)
+		return 2;
+	else if (len > 0x7F)
+		return 1;
+	else
+		return 0;
+}
+
+static void encode_asn_tag(char *buf, unsigned int *ofs, char tag, char seq,
+			   int length)
+{
+	int i;
+	int index = *ofs;
+	char hdr_len = compute_asn_hdr_len_bytes(length);
+	int len = length + 2 + hdr_len;
+
+	/* insert tag */
+	buf[index++] = tag;
+
+	if (!hdr_len) {
+		buf[index++] = len;
+	} else {
+		buf[index++] = 0x80 | hdr_len;
+		for (i = hdr_len - 1; i >= 0; i--)
+			buf[index++] = (len >> (i * 8)) & 0xFF;
+	}
+
+	/* insert seq */
+	len = len - (index - *ofs);
+	buf[index++] = seq;
+
+	if (!hdr_len) {
+		buf[index++] = len;
+	} else {
+		buf[index++] = 0x80 | hdr_len;
+		for (i = hdr_len - 1; i >= 0; i--)
+			buf[index++] = (len >> (i * 8)) & 0xFF;
+	}
+
+	*ofs += (index - *ofs);
+}
+
+int build_spnego_ntlmssp_neg_blob(unsigned char **pbuffer, u16 *buflen,
+				  char *ntlm_blob, int ntlm_blob_len)
+{
+	char *buf;
+	unsigned int ofs = 0;
+	int neg_result_len = 4 + compute_asn_hdr_len_bytes(1) * 2 + 1;
+	int oid_len = 4 + compute_asn_hdr_len_bytes(NTLMSSP_OID_LEN) * 2 +
+		NTLMSSP_OID_LEN;
+	int ntlmssp_len = 4 + compute_asn_hdr_len_bytes(ntlm_blob_len) * 2 +
+		ntlm_blob_len;
+	int total_len = 4 + compute_asn_hdr_len_bytes(neg_result_len +
+			oid_len + ntlmssp_len) * 2 +
+			neg_result_len + oid_len + ntlmssp_len;
+
+	buf = kmalloc(total_len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/* insert main gss header */
+	encode_asn_tag(buf, &ofs, 0xa1, 0x30, neg_result_len + oid_len +
+			ntlmssp_len);
+
+	/* insert neg result */
+	encode_asn_tag(buf, &ofs, 0xa0, 0x0a, 1);
+	buf[ofs++] = 1;
+
+	/* insert oid */
+	encode_asn_tag(buf, &ofs, 0xa1, 0x06, NTLMSSP_OID_LEN);
+	memcpy(buf + ofs, NTLMSSP_OID_STR, NTLMSSP_OID_LEN);
+	ofs += NTLMSSP_OID_LEN;
+
+	/* insert response token - ntlmssp blob */
+	encode_asn_tag(buf, &ofs, 0xa2, 0x04, ntlm_blob_len);
+	memcpy(buf + ofs, ntlm_blob, ntlm_blob_len);
+	ofs += ntlm_blob_len;
+
+	*pbuffer = buf;
+	*buflen = total_len;
+	return 0;
+}
+
+int build_spnego_ntlmssp_auth_blob(unsigned char **pbuffer, u16 *buflen,
+				   int neg_result)
+{
+	char *buf;
+	unsigned int ofs = 0;
+	int neg_result_len = 4 + compute_asn_hdr_len_bytes(1) * 2 + 1;
+	int total_len = 4 + compute_asn_hdr_len_bytes(neg_result_len) * 2 +
+		neg_result_len;
+
+	buf = kmalloc(total_len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/* insert main gss header */
+	encode_asn_tag(buf, &ofs, 0xa1, 0x30, neg_result_len);
+
+	/* insert neg result */
+	encode_asn_tag(buf, &ofs, 0xa0, 0x0a, 1);
+	if (neg_result)
+		buf[ofs++] = 2;
+	else
+		buf[ofs++] = 0;
+
+	*pbuffer = buf;
+	*buflen = total_len;
+	return 0;
+}
+
+int ksmbd_gssapi_this_mech(void *context, size_t hdrlen, unsigned char tag,
+			   const void *value, size_t vlen)
+{
+	unsigned long *oid;
+	size_t oidlen;
+	int err = 0;
+
+	if (!asn1_oid_decode(value, vlen, &oid, &oidlen)) {
+		err = -EBADMSG;
+		goto out;
+	}
+
+	if (!oid_eq(oid, oidlen, SPNEGO_OID, SPNEGO_OID_LEN))
+		err = -EBADMSG;
+	kfree(oid);
+out:
+	if (err) {
+		char buf[50];
+
+		sprint_oid(value, vlen, buf, sizeof(buf));
+		ksmbd_debug(AUTH, "Unexpected OID: %s\n", buf);
+	}
+	return err;
+}
+
+int ksmbd_neg_token_init_mech_type(void *context, size_t hdrlen,
+				   unsigned char tag, const void *value,
+				   size_t vlen)
+{
+	struct ksmbd_conn *conn = context;
+	unsigned long *oid;
+	size_t oidlen;
+	int mech_type;
+	char buf[50];
+
+	if (!asn1_oid_decode(value, vlen, &oid, &oidlen))
+		goto fail;
+
+	if (oid_eq(oid, oidlen, NTLMSSP_OID, NTLMSSP_OID_LEN))
+		mech_type = KSMBD_AUTH_NTLMSSP;
+	else if (oid_eq(oid, oidlen, MSKRB5_OID, MSKRB5_OID_LEN))
+		mech_type = KSMBD_AUTH_MSKRB5;
+	else if (oid_eq(oid, oidlen, KRB5_OID, KRB5_OID_LEN))
+		mech_type = KSMBD_AUTH_KRB5;
+	else if (oid_eq(oid, oidlen, KRB5U2U_OID, KRB5U2U_OID_LEN))
+		mech_type = KSMBD_AUTH_KRB5U2U;
+	else
+		goto fail;
+
+	conn->auth_mechs |= mech_type;
+	if (conn->preferred_auth_mech == 0)
+		conn->preferred_auth_mech = mech_type;
+
+	kfree(oid);
+	return 0;
+
+fail:
+	kfree(oid);
+	sprint_oid(value, vlen, buf, sizeof(buf));
+	ksmbd_debug(AUTH, "Unexpected OID: %s\n", buf);
+	return -EBADMSG;
+}
+
+int ksmbd_neg_token_init_mech_token(void *context, size_t hdrlen,
+				    unsigned char tag, const void *value,
+				    size_t vlen)
+{
+	struct ksmbd_conn *conn = context;
+
+	conn->mechToken = kmalloc(vlen + 1, GFP_KERNEL);
+	if (!conn->mechToken)
+		return -ENOMEM;
+
+	memcpy(conn->mechToken, value, vlen);
+	conn->mechToken[vlen] = '\0';
+	return 0;
+}
+
+int ksmbd_neg_token_targ_resp_token(void *context, size_t hdrlen,
+				    unsigned char tag, const void *value,
+				    size_t vlen)
+{
+	struct ksmbd_conn *conn = context;
+
+	conn->mechToken = kmalloc(vlen + 1, GFP_KERNEL);
+	if (!conn->mechToken)
+		return -ENOMEM;
+
+	memcpy(conn->mechToken, value, vlen);
+	conn->mechToken[vlen] = '\0';
+	return 0;
+}