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[802.11] Add core support for detecting and using encrypted networks

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Signed-off-by: Marty Connor <mdc@etherboot.org>
This commit is contained in:
Joshua Oreman
2009-08-07 22:03:30 -07:00
committed by Marty Connor
parent 8d08da3a99
commit dd8a3e2e70
6 changed files with 1130 additions and 206 deletions
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src/net/80211/sec80211.c Normal file
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/*
* Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
*
* 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <gpxe/ieee80211.h>
#include <gpxe/net80211.h>
#include <gpxe/sec80211.h>
/** @file
*
* General secured-network routines required whenever any secure
* network support at all is compiled in. This involves things like
* installing keys, determining the type of security used by a probed
* network, and some small helper functions that take advantage of
* static data in this file.
*/
/** Mapping from net80211 crypto/secprot types to RSN OUI descriptors */
struct descriptor_map {
/** Value of net80211_crypto_alg or net80211_security_proto */
u32 net80211_type;
/** OUI+type in appropriate byte order, masked to exclude vendor */
u32 oui_type;
};
/** Magic number in @a oui_type showing end of list */
#define END_MAGIC 0xFFFFFFFF
/** Mapping between net80211 cryptosystems and 802.11i cipher IDs */
static struct descriptor_map rsn_cipher_map[] = {
{ .net80211_type = NET80211_CRYPT_WEP,
.oui_type = IEEE80211_RSN_CTYPE_WEP40 },
{ .net80211_type = NET80211_CRYPT_WEP,
.oui_type = IEEE80211_RSN_CTYPE_WEP104 },
{ .net80211_type = NET80211_CRYPT_TKIP,
.oui_type = IEEE80211_RSN_CTYPE_TKIP },
{ .net80211_type = NET80211_CRYPT_CCMP,
.oui_type = IEEE80211_RSN_CTYPE_CCMP },
{ .net80211_type = NET80211_CRYPT_UNKNOWN,
.oui_type = END_MAGIC },
};
/** Mapping between net80211 handshakers and 802.11i AKM IDs */
static struct descriptor_map rsn_akm_map[] = {
{ .net80211_type = NET80211_SECPROT_EAP,
.oui_type = IEEE80211_RSN_ATYPE_8021X },
{ .net80211_type = NET80211_SECPROT_PSK,
.oui_type = IEEE80211_RSN_ATYPE_PSK },
{ .net80211_type = NET80211_SECPROT_UNKNOWN,
.oui_type = END_MAGIC },
};
/**
* Install 802.11 cryptosystem
*
* @v which Pointer to the cryptosystem structure to install in
* @v crypt Cryptosystem ID number
* @v key Encryption key to use
* @v len Length of encryption key
* @v rsc Initial receive sequence counter, if applicable
* @ret rc Return status code
*
* The encryption key will not be accessed via the provided pointer
* after this function returns, so you may keep it on the stack.
*
* @a which must point to either @c dev->crypto (for the normal case
* of installing a unicast cryptosystem) or @c dev->gcrypto (to
* install a cryptosystem that will be used only for decrypting
* group-source frames).
*/
int sec80211_install ( struct net80211_crypto **which,
enum net80211_crypto_alg crypt,
const void *key, int len, const void *rsc )
{
struct net80211_crypto *crypto = *which;
struct net80211_crypto *tbl_crypto;
/* Remove old crypto if it exists */
free ( *which );
*which = NULL;
if ( crypt == NET80211_CRYPT_NONE ) {
DBG ( "802.11-Sec not installing null cryptography\n" );
return 0;
}
/* Find cryptosystem to use */
for_each_table_entry ( tbl_crypto, NET80211_CRYPTOS ) {
if ( tbl_crypto->algorithm == crypt ) {
crypto = zalloc ( sizeof ( *crypto ) +
tbl_crypto->priv_len );
if ( ! crypto ) {
DBG ( "802.11-Sec out of memory\n" );
return -ENOMEM;
}
memcpy ( crypto, tbl_crypto, sizeof ( *crypto ) );
crypto->priv = ( ( void * ) crypto +
sizeof ( *crypto ) );
break;
}
}
if ( ! crypto ) {
DBG ( "802.11-Sec no support for cryptosystem %d\n", crypt );
return -( ENOTSUP | EUNIQ_10 | ( crypt << 8 ) );
}
*which = crypto;
DBG ( "802.11-Sec installing cryptosystem %d as %p with key of "
"length %d\n", crypt, crypto, len );
return crypto->init ( crypto, key, len, rsc );
}
/**
* Determine net80211 crypto or handshaking type value to return for RSN info
*
* @v rsnp Pointer to next descriptor count field in RSN IE
* @v rsn_end Pointer to end of RSN IE
* @v map Descriptor map to use
* @v tbl_start Start of linker table to examine for gPXE support
* @v tbl_end End of linker table to examine for gPXE support
* @ret rsnp Updated to point to first byte after descriptors
* @ret map_ent Descriptor map entry of translation to use
*
* The entries in the linker table must be either net80211_crypto or
* net80211_handshaker structures, and @a tbl_stride must be set to
* sizeof() the appropriate one.
*
* This function expects @a rsnp to point at a two-byte descriptor
* count followed by a list of four-byte cipher or AKM descriptors; it
* will return @c NULL if the input packet is malformed, and otherwise
* set @a rsnp to the first byte it has not looked at. It will return
* the first cipher in the list that is supported by the current build
* of gPXE, or the first of all if none are supported.
*
* We play rather fast and loose with type checking, because this
* function is only called from two well-defined places in the
* RSN-checking code. Don't try to use it for anything else.
*/
static struct descriptor_map * rsn_pick_desc ( u8 **rsnp, u8 *rsn_end,
struct descriptor_map *map,
void *tbl_start, void *tbl_end )
{
int ndesc;
int ok = 0;
struct descriptor_map *map_ent, *map_ret = NULL;
u8 *rsn = *rsnp;
void *tblp;
size_t tbl_stride = ( map == rsn_cipher_map ?
sizeof ( struct net80211_crypto ) :
sizeof ( struct net80211_handshaker ) );
if ( map != rsn_cipher_map && map != rsn_akm_map )
return NULL;
/* Determine which types we support */
for ( tblp = tbl_start; tblp < tbl_end; tblp += tbl_stride ) {
struct net80211_crypto *crypto = tblp;
struct net80211_handshaker *hs = tblp;
if ( map == rsn_cipher_map )
ok |= ( 1 << crypto->algorithm );
else
ok |= ( 1 << hs->protocol );
}
/* RSN sanity checks */
if ( rsn + 2 > rsn_end ) {
DBG ( "RSN detect: malformed descriptor count\n" );
return NULL;
}
ndesc = *( u16 * ) rsn;
rsn += 2;
if ( ! ndesc ) {
DBG ( "RSN detect: no descriptors\n" );
return NULL;
}
/* Determine which net80211 crypto types are listed */
while ( ndesc-- ) {
u32 desc;
if ( rsn + 4 > rsn_end ) {
DBG ( "RSN detect: malformed descriptor (%d left)\n",
ndesc );
return NULL;
}
desc = *( u32 * ) rsn;
rsn += 4;
for ( map_ent = map; map_ent->oui_type != END_MAGIC; map_ent++ )
if ( map_ent->oui_type == ( desc & OUI_TYPE_MASK ) )
break;
/* Use first cipher as a fallback */
if ( ! map_ret )
map_ret = map_ent;
/* Once we find one we support, use it */
if ( ok & ( 1 << map_ent->net80211_type ) ) {
map_ret = map_ent;
break;
}
}
if ( ndesc > 0 )
rsn += 4 * ndesc;
*rsnp = rsn;
return map_ret;
}
/**
* Find the RSN or WPA information element in the provided beacon frame
*
* @v ie Pointer to first information element to check
* @v ie_end Pointer to end of information element space
* @ret is_rsn TRUE if returned IE is RSN, FALSE if it's WPA
* @ret end Pointer to byte immediately after last byte of data
* @ret data Pointer to first byte of data (the `version' field)
*
* If both an RSN and a WPA information element are found, this
* function will return the first one seen, which by ordering rules
* should always prefer the newer RSN IE.
*
* If no RSN or WPA infomration element is found, returns @c NULL and
* leaves @a is_rsn and @a end in an undefined state.
*
* This function will not return a pointer to an information element
* that states it extends past the tail of the io_buffer, or whose @a
* version field is incorrect.
*/
u8 * sec80211_find_rsn ( union ieee80211_ie *ie, void *ie_end,
int *is_rsn, u8 **end )
{
u8 *rsn = NULL;
if ( ! ieee80211_ie_bound ( ie, ie_end ) )
return NULL;
while ( ie ) {
if ( ie->id == IEEE80211_IE_VENDOR &&
ie->vendor.oui == IEEE80211_WPA_OUI_VEN ) {
DBG ( "RSN detect: old-style WPA IE found\n" );
rsn = &ie->vendor.data[0];
*end = rsn + ie->len - 4;
*is_rsn = 0;
} else if ( ie->id == IEEE80211_IE_RSN ) {
DBG ( "RSN detect: 802.11i RSN IE found\n" );
rsn = ( u8 * ) &ie->rsn.version;
*end = rsn + ie->len;
*is_rsn = 1;
}
if ( rsn && ( *end > ( u8 * ) ie_end || rsn >= *end ||
*( u16 * ) rsn != IEEE80211_RSN_VERSION ) ) {
DBG ( "RSN detect: malformed RSN IE or unknown "
"version, keep trying\n" );
rsn = NULL;
}
if ( rsn )
break;
ie = ieee80211_next_ie ( ie, ie_end );
}
if ( ! ie ) {
DBG ( "RSN detect: no RSN IE found\n" );
return NULL;
}
return rsn;
}
/**
* Detect crypto and AKM types from RSN information element
*
* @v is_rsn If TRUE, IE is a new-style RSN information element
* @v start Pointer to first byte of @a version field
* @v end Pointer to first byte not in the RSN IE
* @ret secprot Security handshaking protocol used by network
* @ret crypt Cryptosystem used by network
* @ret rc Return status code
*
* If the IE cannot be parsed, returns an error indication and leaves
* @a secprot and @a crypt unchanged.
*/
int sec80211_detect_ie ( int is_rsn, u8 *start, u8 *end,
enum net80211_security_proto *secprot,
enum net80211_crypto_alg *crypt )
{
enum net80211_security_proto sp;
enum net80211_crypto_alg cr;
struct descriptor_map *map;
u8 *rsn = start;
/* Set some defaults */
cr = ( is_rsn ? NET80211_CRYPT_CCMP : NET80211_CRYPT_TKIP );
sp = NET80211_SECPROT_EAP;
rsn += 2; /* version - already checked */
rsn += 4; /* group cipher - we don't use it here */
if ( rsn >= end )
goto done;
/* Pick crypto algorithm */
map = rsn_pick_desc ( &rsn, end, rsn_cipher_map,
table_start ( NET80211_CRYPTOS ),
table_end ( NET80211_CRYPTOS ) );
if ( ! map )
goto invalid_rsn;
cr = map->net80211_type;
if ( rsn >= end )
goto done;
/* Pick handshaking algorithm */
map = rsn_pick_desc ( &rsn, end, rsn_akm_map,
table_start ( NET80211_HANDSHAKERS ),
table_end ( NET80211_HANDSHAKERS ) );
if ( ! map )
goto invalid_rsn;
sp = map->net80211_type;
done:
DBG ( "RSN detect: OK, crypto type %d, secprot type %d\n", cr, sp );
*secprot = sp;
*crypt = cr;
return 0;
invalid_rsn:
DBG ( "RSN detect: invalid RSN IE\n" );
return -EINVAL;
}
/**
* Detect the cryptosystem and handshaking protocol used by an 802.11 network
*
* @v iob I/O buffer containing beacon frame
* @ret secprot Security handshaking protocol used by network
* @ret crypt Cryptosystem used by network
* @ret rc Return status code
*
* This function uses weak linkage, as it must be called from generic
* contexts but should only be linked in if some encryption is
* supported; you must test its address against @c NULL before calling
* it. If it does not exist, any network with the PRIVACY bit set in
* beacon->capab should be considered unknown.
*/
int _sec80211_detect ( struct io_buffer *iob,
enum net80211_security_proto *secprot,
enum net80211_crypto_alg *crypt )
{
struct ieee80211_frame *hdr = iob->data;
struct ieee80211_beacon *beacon =
( struct ieee80211_beacon * ) hdr->data;
u8 *rsn, *rsn_end;
int is_rsn, rc;
*crypt = NET80211_CRYPT_UNKNOWN;
*secprot = NET80211_SECPROT_UNKNOWN;
/* Find RSN or WPA IE */
if ( ! ( rsn = sec80211_find_rsn ( beacon->info_element, iob->tail,
&is_rsn, &rsn_end ) ) ) {
/* No security IE at all; either WEP or no security. */
*secprot = NET80211_SECPROT_NONE;
if ( beacon->capability & IEEE80211_CAPAB_PRIVACY )
*crypt = NET80211_CRYPT_WEP;
else
*crypt = NET80211_CRYPT_NONE;
return 0;
}
/* Determine type of security */
if ( ( rc = sec80211_detect_ie ( is_rsn, rsn, rsn_end, secprot,
crypt ) ) == 0 )
return 0;
/* If we get here, the RSN IE was invalid */
*crypt = NET80211_CRYPT_UNKNOWN;
*secprot = NET80211_SECPROT_UNKNOWN;
DBG ( "Failed to handle RSN IE:\n" );
DBG_HD ( rsn, rsn_end - rsn );
return rc;
}
/**
* Determine RSN descriptor for specified net80211 ID
*
* @v id net80211 ID value
* @v rsnie Whether to return a new-format (RSN IE) descriptor
* @v map Map to use in translation
* @ret desc RSN descriptor, or 0 on error
*
* If @a rsnie is false, returns an old-format (WPA vendor IE)
* descriptor.
*/
static u32 rsn_get_desc ( unsigned id, int rsnie, struct descriptor_map *map )
{
u32 vendor = ( rsnie ? IEEE80211_RSN_OUI : IEEE80211_WPA_OUI );
for ( ; map->oui_type != END_MAGIC; map++ ) {
if ( map->net80211_type == id )
return map->oui_type | vendor;
}
return 0;
}
/**
* Determine RSN descriptor for specified net80211 cryptosystem number
*
* @v crypt Cryptosystem number
* @v rsnie Whether to return a new-format (RSN IE) descriptor
* @ret desc RSN descriptor
*
* If @a rsnie is false, returns an old-format (WPA vendor IE)
* descriptor.
*/
u32 sec80211_rsn_get_crypto_desc ( enum net80211_crypto_alg crypt, int rsnie )
{
return rsn_get_desc ( crypt, rsnie, rsn_cipher_map );
}
/**
* Determine RSN descriptor for specified net80211 handshaker number
*
* @v secprot Handshaker number
* @v rsnie Whether to return a new-format (RSN IE) descriptor
* @ret desc RSN descriptor
*
* If @a rsnie is false, returns an old-format (WPA vendor IE)
* descriptor.
*/
u32 sec80211_rsn_get_akm_desc ( enum net80211_security_proto secprot,
int rsnie )
{
return rsn_get_desc ( secprot, rsnie, rsn_akm_map );
}
/**
* Determine net80211 cryptosystem number from RSN descriptor
*
* @v desc RSN descriptor
* @ret crypt net80211 cryptosystem enumeration value
*/
enum net80211_crypto_alg sec80211_rsn_get_net80211_crypt ( u32 desc )
{
struct descriptor_map *map = rsn_cipher_map;
for ( ; map->oui_type != END_MAGIC; map++ ) {
if ( map->oui_type == ( desc & OUI_TYPE_MASK ) )
break;
}
return map->net80211_type;
}