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linux/fs/cifs/asn1.c
Chris Wright ddb2c43594 asn1: additional sanity checking during BER decoding 
- Don't trust a length which is greater than the working buffer.
  An invalid length could cause overflow when calculating buffer size
  for decoding oid.

- An oid length of zero is invalid and allows for an off-by-one error when
  decoding oid because the first subid actually encodes first 2 subids.

- A primitive encoding may not have an indefinite length.

Thanks to Wei Wang from McAfee for report.

Cc: Steven French <sfrench@us.ibm.com>
Cc: stable@kernel.org
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-05 14:24:54 -07:00

648 lines
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/*
* 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).
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include "cifspdu.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_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 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 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;
}
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 > ULONG_MAX/sizeof(unsigned long))
return 0;
*oid = kmalloc(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 */
int
decode_negTokenInit(unsigned char *security_blob, int length,
enum securityEnum *secType)
{
struct asn1_ctx ctx;
unsigned char *end;
unsigned char *sequence_end;
unsigned long *oid = NULL;
unsigned int cls, con, tag, oidlen, rc;
bool use_ntlmssp = false;
bool use_kerberos = false;
*secType = NTLM; /* BB eventually make Kerberos or NLTMSSP the default*/
/* cifs_dump_mem(" Received SecBlob ", security_blob, length); */
asn1_open(&ctx, security_blob, length);
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cFYI(1, ("Error decoding negTokenInit header"));
return 0;
} else if ((cls != ASN1_APL) || (con != ASN1_CON)
|| (tag != ASN1_EOC)) {
cFYI(1, ("cls = %d con = %d tag = %d", cls, con, tag));
return 0;
} else {
/* remember to free obj->oid */
rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
if (rc) {
if ((tag == ASN1_OJI) && (cls == ASN1_PRI)) {
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;
}
if (!rc) {
cFYI(1, ("Error decoding negTokenInit header"));
return 0;
}
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cFYI(1, ("Error decoding negTokenInit"));
return 0;
} else if ((cls != ASN1_CTX) || (con != ASN1_CON)
|| (tag != ASN1_EOC)) {
cFYI(1,
("cls = %d con = %d tag = %d end = %p (%d) exit 0",
cls, con, tag, end, *end));
return 0;
}
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cFYI(1, ("Error decoding negTokenInit"));
return 0;
} else if ((cls != ASN1_UNI) || (con != ASN1_CON)
|| (tag != ASN1_SEQ)) {
cFYI(1,
("cls = %d con = %d tag = %d end = %p (%d) exit 1",
cls, con, tag, end, *end));
return 0;
}
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cFYI(1, ("Error decoding 2nd part of negTokenInit"));
return 0;
} else if ((cls != ASN1_CTX) || (con != ASN1_CON)
|| (tag != ASN1_EOC)) {
cFYI(1,
("cls = %d con = %d tag = %d end = %p (%d) exit 0",
cls, con, tag, end, *end));
return 0;
}
if (asn1_header_decode
(&ctx, &sequence_end, &cls, &con, &tag) == 0) {
cFYI(1, ("Error decoding 2nd part of negTokenInit"));
return 0;
} else if ((cls != ASN1_UNI) || (con != ASN1_CON)
|| (tag != ASN1_SEQ)) {
cFYI(1,
("cls = %d con = %d tag = %d end = %p (%d) exit 1",
cls, con, tag, end, *end));
return 0;
}
while (!asn1_eoc_decode(&ctx, sequence_end)) {
rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
if (!rc) {
cFYI(1,
("Error decoding negTokenInit hdr exit2"));
return 0;
}
if ((tag == ASN1_OJI) && (con == ASN1_PRI)) {
if (asn1_oid_decode(&ctx, end, &oid, &oidlen)) {
cFYI(1,
("OID len = %d oid = 0x%lx 0x%lx "
"0x%lx 0x%lx",
oidlen, *oid, *(oid + 1),
*(oid + 2), *(oid + 3)));
if (compare_oid(oid, oidlen,
MSKRB5_OID,
MSKRB5_OID_LEN))
use_kerberos = true;
else if (compare_oid(oid, oidlen,
KRB5_OID,
KRB5_OID_LEN))
use_kerberos = true;
else if (compare_oid(oid, oidlen,
NTLMSSP_OID,
NTLMSSP_OID_LEN))
use_ntlmssp = true;
kfree(oid);
}
} else {
cFYI(1, ("Should be an oid what is going on?"));
}
}
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cFYI(1,
("Error decoding last part negTokenInit exit3"));
return 0;
} else if ((cls != ASN1_CTX) || (con != ASN1_CON)) {
/* tag = 3 indicating mechListMIC */
cFYI(1,
("Exit 4 cls = %d con = %d tag = %d end = %p (%d)",
cls, con, tag, end, *end));
return 0;
}
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cFYI(1,
("Error decoding last part negTokenInit exit5"));
return 0;
} else if ((cls != ASN1_UNI) || (con != ASN1_CON)
|| (tag != ASN1_SEQ)) {
cFYI(1, ("cls = %d con = %d tag = %d end = %p (%d)",
cls, con, tag, end, *end));
}
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cFYI(1,
("Error decoding last part negTokenInit exit 7"));
return 0;
} else if ((cls != ASN1_CTX) || (con != ASN1_CON)) {
cFYI(1,
("Exit 8 cls = %d con = %d tag = %d end = %p (%d)",
cls, con, tag, end, *end));
return 0;
}
if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
cFYI(1,
("Error decoding last part negTokenInit exit9"));
return 0;
} else if ((cls != ASN1_UNI) || (con != ASN1_PRI)
|| (tag != ASN1_GENSTR)) {
cFYI(1,
("Exit10 cls = %d con = %d tag = %d end = %p (%d)",
cls, con, tag, end, *end));
return 0;
}
cFYI(1, ("Need to call asn1_octets_decode() function for %s",
ctx.pointer)); /* is this UTF-8 or ASCII? */
}
if (use_kerberos)
*secType = Kerberos;
else if (use_ntlmssp)
*secType = NTLMSSP;
return 1;
}
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