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cifs: decoding negTokenInit with generic ASN1 decoder

Browse source 
Decode negTokenInit with lib/asn1_decoder. For that,
add OIDs in linux/oid_registry.h and a negTokenInit
ASN1 file, "spnego_negtokeninit.asn1".
And define decoder's callback functions, which
are the gssapi_this_mech for checking SPENGO oid and
the neg_token_init_mech_type for getting authentication
mechanisms supported by a server.

Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Hyunchul Lee 2021-06-08 23:53:14 +09:00 committed by Steve French
parent 1023e90b73
commit 0475c3655e
5 changed files with 105 additions and 600 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
fs/cifs/Kconfig
View file

@ -19,6 +19,8 @@ config CIFS
select CRYPTO_LIB_DES
select KEYS
select DNS_RESOLVER
select ASN1
select OID_REGISTRY
help
This is the client VFS module for the SMB3 family of NAS protocols,
(including support for the most recent, most secure dialect SMB3.1.1)

8
fs/cifs/Makefile
View file

@ -6,12 +6,16 @@ ccflags-y += -I$(src) # needed for trace events
obj-$(CONFIG_CIFS) += cifs.o
cifs-y := trace.o cifsfs.o cifssmb.o cifs_debug.o connect.o dir.o file.o \
inode.o link.o misc.o netmisc.o smbencrypt.o transport.o asn1.o \
inode.o link.o misc.o netmisc.o smbencrypt.o transport.o \
cifs_unicode.o nterr.o cifsencrypt.o \
readdir.o ioctl.o sess.o export.o smb1ops.o unc.o winucase.o \
smb2ops.o smb2maperror.o smb2transport.o \
smb2misc.o smb2pdu.o smb2inode.o smb2file.o cifsacl.o fs_context.o \
dns_resolve.o
dns_resolve.o cifs_spnego_negtokeninit.asn1.o asn1.o
$(obj)/asn1.o: $(obj)/cifs_spnego_negtokeninit.asn1.h
$(obj)/cifs_spnego_negtokeninit.asn1.o: $(obj)/cifs_spnego_negtokeninit.asn1.c $(obj)/cifs_spnego_negtokeninit.asn1.h
cifs-$(CONFIG_CIFS_XATTR) += xattr.o

647
fs/cifs/asn1.c
View file

@ -1,612 +1,63 @@
// 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 "cifspdu.h"
#include <linux/oid_registry.h>
#include "cifsglob.h"
#include "cifs_debug.h"
#include "cifsproto.h"
/*****************************************************************************
*
* Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse)
*
*****************************************************************************/
/* Class */
#define ASN1_UNI 0 /* Universal */
#define ASN1_APL 1 /* Application */
#define ASN1_CTX 2 /* Context */
#define ASN1_PRV 3 /* Private */
/* Tag */
#define ASN1_EOC 0 /* End Of Contents or N/A */
#define ASN1_BOL 1 /* Boolean */
#define ASN1_INT 2 /* Integer */
#define ASN1_BTS 3 /* Bit String */
#define ASN1_OTS 4 /* Octet String */
#define ASN1_NUL 5 /* Null */
#define ASN1_OJI 6 /* Object Identifier */
#define ASN1_OJD 7 /* Object Description */
#define ASN1_EXT 8 /* External */
#define ASN1_ENUM 10 /* Enumerated */
#define ASN1_SEQ 16 /* Sequence */
#define ASN1_SET 17 /* Set */
#define ASN1_NUMSTR 18 /* Numerical String */
#define ASN1_PRNSTR 19 /* Printable String */
#define ASN1_TEXSTR 20 /* Teletext String */
#define ASN1_VIDSTR 21 /* Video String */
#define ASN1_IA5STR 22 /* IA5 String */
#define ASN1_UNITIM 23 /* Universal Time */
#define ASN1_GENTIM 24 /* General Time */
#define ASN1_GRASTR 25 /* Graphical String */
#define ASN1_VISSTR 26 /* Visible String */
#define ASN1_GENSTR 27 /* General String */
/* Primitive / Constructed methods*/
#define ASN1_PRI 0 /* Primitive */
#define ASN1_CON 1 /* Constructed */
/*
* Error codes.
*/
#define ASN1_ERR_NOERROR 0
#define ASN1_ERR_DEC_EMPTY 2
#define ASN1_ERR_DEC_EOC_MISMATCH 3
#define ASN1_ERR_DEC_LENGTH_MISMATCH 4
#define ASN1_ERR_DEC_BADVALUE 5
#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 };
/*
* ASN.1 context.
*/
struct asn1_ctx {
int error; /* Error condition */
unsigned char *pointer; /* Octet just to be decoded */
unsigned char *begin; /* First octet */
unsigned char *end; /* Octet after last octet */
};
/*
* Octet string (not null terminated)
*/
struct asn1_octstr {
unsigned char *data;
unsigned int len;
};
static void
asn1_open(struct asn1_ctx *ctx, unsigned char *buf, unsigned int len)
{
ctx->begin = buf;
ctx->end = buf + len;
ctx->pointer = buf;
ctx->error = ASN1_ERR_NOERROR;
}
static unsigned char
asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch)
{
if (ctx->pointer >= ctx->end) {
ctx->error = ASN1_ERR_DEC_EMPTY;
return 0;
}
*ch = *(ctx->pointer)++;
return 1;
}
#if 0 /* will be needed later by spnego decoding/encoding of ntlmssp */
static unsigned char
asn1_enum_decode(struct asn1_ctx *ctx, __le32 *val)
{
unsigned char ch;
if (ctx->pointer >= ctx->end) {
ctx->error = ASN1_ERR_DEC_EMPTY;
return 0;
}
ch = *(ctx->pointer)++; /* ch has 0xa, ptr points to length octet */
if ((ch) == ASN1_ENUM) /* if ch value is ENUM, 0xa */
*val = *(++(ctx->pointer)); /* value has enum value */
else
return 0;
ctx->pointer++;
return 1;
}
#endif
static unsigned char
asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
{
unsigned char ch;
*tag = 0;
do {
if (!asn1_octet_decode(ctx, &ch))
return 0;
*tag <<= 7;
*tag |= ch & 0x7F;
} while ((ch & 0x80) == 0x80);
return 1;
}
static unsigned char
asn1_id_decode(struct asn1_ctx *ctx,
unsigned int *cls, unsigned int *con, unsigned int *tag)
{
unsigned char ch;
if (!asn1_octet_decode(ctx, &ch))
return 0;
*cls = (ch & 0xC0) >> 6;
*con = (ch & 0x20) >> 5;
*tag = (ch & 0x1F);
if (*tag == 0x1F) {
if (!asn1_tag_decode(ctx, tag))
return 0;
}
return 1;
}
static unsigned char
asn1_length_decode(struct asn1_ctx *ctx, unsigned int *def, unsigned int *len)
{
unsigned char ch, cnt;
if (!asn1_octet_decode(ctx, &ch))
return 0;
if (ch == 0x80)
*def = 0;
else {
*def = 1;
if (ch < 0x80)
*len = ch;
else {
cnt = (unsigned char) (ch & 0x7F);
*len = 0;
while (cnt > 0) {
if (!asn1_octet_decode(ctx, &ch))
return 0;
*len <<= 8;
*len |= ch;
cnt--;
}
}
}
/* don't trust len bigger than ctx buffer */
if (*len > ctx->end - ctx->pointer)
return 0;
return 1;
}
static unsigned char
asn1_header_decode(struct asn1_ctx *ctx,
unsigned char **eoc,
unsigned int *cls, unsigned int *con, unsigned int *tag)
{
unsigned int def = 0;
unsigned int len = 0;
if (!asn1_id_decode(ctx, cls, con, tag))
return 0;
if (!asn1_length_decode(ctx, &def, &len))
return 0;
/* primitive shall be definite, indefinite shall be constructed */
if (*con == ASN1_PRI && !def)
return 0;
if (def)
*eoc = ctx->pointer + len;
else
*eoc = NULL;
return 1;
}
static unsigned char
asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
{
unsigned char ch;
if (eoc == NULL) {
if (!asn1_octet_decode(ctx, &ch))
return 0;
if (ch != 0x00) {
ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
return 0;
}
if (!asn1_octet_decode(ctx, &ch))
return 0;
if (ch != 0x00) {
ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
return 0;
}
return 1;
} else {
if (ctx->pointer != eoc) {
ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH;
return 0;
}
return 1;
}
}
/* static unsigned char asn1_null_decode(struct asn1_ctx *ctx,
unsigned char *eoc)
{
ctx->pointer = eoc;
return 1;
}
static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
unsigned char *eoc, long *integer)
{
unsigned char ch;
unsigned int len;
if (!asn1_octet_decode(ctx, &ch))
return 0;
*integer = (signed char) ch;
len = 1;
while (ctx->pointer < eoc) {
if (++len > sizeof(long)) {
ctx->error = ASN1_ERR_DEC_BADVALUE;
return 0;
}
if (!asn1_octet_decode(ctx, &ch))
return 0;
*integer <<= 8;
*integer |= ch;
}
return 1;
}
static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
unsigned char *eoc,
unsigned int *integer)
{
unsigned char ch;
unsigned int len;
if (!asn1_octet_decode(ctx, &ch))
return 0;
*integer = ch;
if (ch == 0)
len = 0;
else
len = 1;
while (ctx->pointer < eoc) {
if (++len > sizeof(unsigned int)) {
ctx->error = ASN1_ERR_DEC_BADVALUE;
return 0;
}
if (!asn1_octet_decode(ctx, &ch))
return 0;
*integer <<= 8;
*integer |= ch;
}
return 1;
}
static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx,
unsigned char *eoc,
unsigned long *integer)
{
unsigned char ch;
unsigned int len;
if (!asn1_octet_decode(ctx, &ch))
return 0;
*integer = ch;
if (ch == 0)
len = 0;
else
len = 1;
while (ctx->pointer < eoc) {
if (++len > sizeof(unsigned long)) {
ctx->error = ASN1_ERR_DEC_BADVALUE;
return 0;
}
if (!asn1_octet_decode(ctx, &ch))
return 0;
*integer <<= 8;
*integer |= ch;
}
return 1;
}
static unsigned char
asn1_octets_decode(struct asn1_ctx *ctx,
unsigned char *eoc,
unsigned char **octets, unsigned int *len)
{
unsigned char *ptr;
*len = 0;
*octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
if (*octets == NULL) {
return 0;
}
ptr = *octets;
while (ctx->pointer < eoc) {
if (!asn1_octet_decode(ctx, (unsigned char *) ptr++)) {
kfree(*octets);
*octets = NULL;
return 0;
}
(*len)++;
}
return 1;
} */
static unsigned char
asn1_subid_decode(struct asn1_ctx *ctx, unsigned long *subid)
{
unsigned char ch;
*subid = 0;
do {
if (!asn1_octet_decode(ctx, &ch))
return 0;
*subid <<= 7;
*subid |= ch & 0x7F;
} while ((ch & 0x80) == 0x80);
return 1;
}
static int
asn1_oid_decode(struct asn1_ctx *ctx,
unsigned char *eoc, unsigned long **oid, unsigned int *len)
{
unsigned long subid;
unsigned int size;
unsigned long *optr;
size = eoc - ctx->pointer + 1;
/* first subid actually encodes first two subids */
if (size < 2 || size > UINT_MAX/sizeof(unsigned long))
return 0;
*oid = kmalloc_array(size, sizeof(unsigned long), GFP_ATOMIC);
if (*oid == NULL)
return 0;
optr = *oid;
if (!asn1_subid_decode(ctx, &subid)) {
kfree(*oid);
*oid = NULL;
return 0;
}
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;
}
*len = 2;
optr += 2;
while (ctx->pointer < eoc) {
if (++(*len) > size) {
ctx->error = ASN1_ERR_DEC_BADVALUE;
kfree(*oid);
*oid = NULL;
return 0;
}
if (!asn1_subid_decode(ctx, optr++)) {
kfree(*oid);
*oid = NULL;
return 0;
}
}
return 1;
}
static int
compare_oid(unsigned long *oid1, unsigned int oid1len,
unsigned long *oid2, unsigned int oid2len)
{
unsigned int i;
if (oid1len != oid2len)
return 0;
else {
for (i = 0; i < oid1len; i++) {
if (oid1[i] != oid2[i])
return 0;
}
return 1;
}
}
/* BB check for endian conversion issues here */
#include "cifs_spnego_negtokeninit.asn1.h"
int
decode_negTokenInit(unsigned char *security_blob, int length,
struct TCP_Server_Info *server)
{
struct asn1_ctx ctx;
unsigned char *end;
unsigned char *sequence_end;
unsigned long *oid = NULL;
unsigned int cls, con, tag, oidlen, rc;
/* cifs_dump_mem(" Received SecBlob ", security_blob, length); */
asn1_open(&ctx, security_blob, length);
/* GSSAPI header */
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cifs_dbg(FYI, "Error decoding negTokenInit header\n");
if (asn1_ber_decoder(&cifs_spnego_negtokeninit_decoder, server,
security_blob, length) == 0)
return 1;
else
return 0;
} else if ((cls != ASN1_APL) || (con != ASN1_CON)
|| (tag != ASN1_EOC)) {
cifs_dbg(FYI, "cls = %d con = %d tag = %d\n", cls, con, tag);
return 0;
}
/* Check for SPNEGO OID -- remember to free obj->oid */
rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
if (rc) {
if ((tag == ASN1_OJI) && (con == ASN1_PRI) &&
(cls == ASN1_UNI)) {
rc = asn1_oid_decode(&ctx, end, &oid, &oidlen);
if (rc) {
rc = compare_oid(oid, oidlen, SPNEGO_OID,
SPNEGO_OID_LEN);
kfree(oid);
}
} else
rc = 0;
}
/* SPNEGO OID not present or garbled -- bail out */
if (!rc) {
cifs_dbg(FYI, "Error decoding negTokenInit header\n");
return 0;
}
/* SPNEGO */
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cifs_dbg(FYI, "Error decoding negTokenInit\n");
return 0;
} else if ((cls != ASN1_CTX) || (con != ASN1_CON)
|| (tag != ASN1_EOC)) {
cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p exit 0\n",
cls, con, tag, end);
return 0;
}
/* negTokenInit */
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cifs_dbg(FYI, "Error decoding negTokenInit\n");
return 0;
} else if ((cls != ASN1_UNI) || (con != ASN1_CON)
|| (tag != ASN1_SEQ)) {
cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p exit 1\n",
cls, con, tag, end);
return 0;
}
/* sequence */
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cifs_dbg(FYI, "Error decoding 2nd part of negTokenInit\n");
return 0;
} else if ((cls != ASN1_CTX) || (con != ASN1_CON)
|| (tag != ASN1_EOC)) {
cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p exit 0\n",
cls, con, tag, end);
return 0;
}
/* sequence of */
if (asn1_header_decode
(&ctx, &sequence_end, &cls, &con, &tag) == 0) {
cifs_dbg(FYI, "Error decoding 2nd part of negTokenInit\n");
return 0;
} else if ((cls != ASN1_UNI) || (con != ASN1_CON)
|| (tag != ASN1_SEQ)) {
cifs_dbg(FYI, "cls = %d con = %d tag = %d sequence_end = %p exit 1\n",
cls, con, tag, sequence_end);
return 0;
}
/* list of security mechanisms */
while (!asn1_eoc_decode(&ctx, sequence_end)) {
rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
if (!rc) {
cifs_dbg(FYI, "Error decoding negTokenInit hdr exit2\n");
return 0;
}
if ((tag == ASN1_OJI) && (con == ASN1_PRI)) {
if (asn1_oid_decode(&ctx, end, &oid, &oidlen)) {
cifs_dbg(FYI, "OID len = %d oid = 0x%lx 0x%lx 0x%lx 0x%lx\n",
oidlen, *oid, *(oid + 1), *(oid + 2),
*(oid + 3));
if (compare_oid(oid, oidlen, MSKRB5_OID,
MSKRB5_OID_LEN))
server->sec_mskerberos = true;
else if (compare_oid(oid, oidlen, KRB5U2U_OID,
KRB5U2U_OID_LEN))
server->sec_kerberosu2u = true;
else if (compare_oid(oid, oidlen, KRB5_OID,
KRB5_OID_LEN))
server->sec_kerberos = true;
else if (compare_oid(oid, oidlen, NTLMSSP_OID,
NTLMSSP_OID_LEN))
server->sec_ntlmssp = true;
kfree(oid);
}
} else {
cifs_dbg(FYI, "Should be an oid what is going on?\n");
}
}
/*
* We currently ignore anything at the end of the SPNEGO blob after
* the mechTypes have been parsed, since none of that info is
* used at the moment.
*/
return 1;
}
int cifs_gssapi_this_mech(void *context, size_t hdrlen,
unsigned char tag, const void *value, size_t vlen)
{
enum OID oid;
oid = look_up_OID(value, vlen);
if (oid != OID_spnego) {
char buf[50];
sprint_oid(value, vlen, buf, sizeof(buf));
cifs_dbg(FYI, "Error decoding negTokenInit header: unexpected OID %s\n",
buf);
return -EBADMSG;
}
return 0;
}
int cifs_neg_token_init_mech_type(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct TCP_Server_Info *server = context;
enum OID oid;
oid = look_up_OID(value, vlen);
if (oid == OID_mskrb5)
server->sec_mskerberos = true;
else if (oid == OID_krb5u2u)
server->sec_kerberosu2u = true;
else if (oid == OID_krb5)
server->sec_kerberos = true;
else if (oid == OID_ntlmssp)
server->sec_ntlmssp = true;
else {
char buf[50];
sprint_oid(value, vlen, buf, sizeof(buf));
cifs_dbg(FYI, "Decoding negTokenInit: unsupported OID %s\n",
buf);
}
return 0;
}

40
fs/cifs/cifs_spnego_negtokeninit.asn1 Normal file
View file

@ -0,0 +1,40 @@
GSSAPI ::=
[APPLICATION 0] IMPLICIT SEQUENCE {
thisMech
OBJECT IDENTIFIER ({cifs_gssapi_this_mech}),
negotiationToken
NegotiationToken
}
MechType ::= OBJECT IDENTIFIER ({cifs_neg_token_init_mech_type})
MechTypeList ::= SEQUENCE OF MechType
NegHints ::= SEQUENCE {
hintName
[0] GeneralString OPTIONAL,
hintAddress
[1] OCTET STRING OPTIONAL
}
NegTokenInit2 ::=
SEQUENCE {
mechTypes
[0] MechTypeList OPTIONAL,
reqFlags
[1] BIT STRING OPTIONAL,
mechToken
[2] OCTET STRING OPTIONAL,
negHints
[3] NegHints OPTIONAL,
mechListMIC
[3] OCTET STRING OPTIONAL
}
NegotiationToken ::=
CHOICE {
negTokenInit
[0] NegTokenInit2,
negTokenTarg
[1] ANY
}

8
include/linux/oid_registry.h
View file

@ -54,6 +54,10 @@ enum OID {
OID_md4, /* 1.2.840.113549.2.4 */
OID_md5, /* 1.2.840.113549.2.5 */
OID_mskrb5, /* 1.2.840.48018.1.2.2 */
OID_krb5, /* 1.2.840.113554.1.2.2 */
OID_krb5u2u, /* 1.2.840.113554.1.2.2.3 */
/* Microsoft Authenticode & Software Publishing */
OID_msIndirectData, /* 1.3.6.1.4.1.311.2.1.4 */
OID_msStatementType, /* 1.3.6.1.4.1.311.2.1.11 */
@ -62,6 +66,10 @@ enum OID {
OID_msIndividualSPKeyPurpose, /* 1.3.6.1.4.1.311.2.1.21 */
OID_msOutlookExpress, /* 1.3.6.1.4.1.311.16.4 */
OID_ntlmssp, /* 1.3.6.1.4.1.311.2.2.10 */
OID_spnego, /* 1.3.6.1.5.5.2 */
OID_certAuthInfoAccess, /* 1.3.6.1.5.5.7.1.1 */
OID_sha1, /* 1.3.14.3.2.26 */
OID_id_ansip384r1, /* 1.3.132.0.34 */