Skip to content

Commit

Permalink
Merge branch '6lowpan'
Browse files Browse the repository at this point in the history 
Alexander Aring says:

====================
6lowpan: address uncompression fixes

The current implementation to uncompress addresses in a 6lowpan header
is completely broken.

This patch series fixes the parsing of addresses in a 6lowpan header.
It contains a major rewrite of the uncompress address function to parse
the address in a correct way.

Tested with the ravenusbstick(contiki 6LoWPAN stack) and beaglebone
(linux 6LoWPAN Stack) on the other side. The linux side contains all
possible addresses for the uncompression cases. Then I type a ping6 for
each case and lookup in wireshark and dmesg the correct reconstruction.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
  • Loading branch information
David S. Miller committed Aug 20, 2013
2 parents 4cffa13 + 65d892c commit 15ec80f
Show file tree
Hide file tree
Showing 2 changed files with 204 additions and 102 deletions.
286 changes: 187 additions & 99 deletions net/ieee802154/6lowpan.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -67,39 +67,6 @@ static const u8 lowpan_ttl_values[] = {0, 1, 64, 255};

static LIST_HEAD(lowpan_devices);

/*
* Uncompression of linklocal:
* 0 -> 16 bytes from packet
* 1 -> 2 bytes from prefix - bunch of zeroes and 8 from packet
* 2 -> 2 bytes from prefix - zeroes + 2 from packet
* 3 -> 2 bytes from prefix - infer 8 bytes from lladdr
*
* NOTE: => the uncompress function does change 0xf to 0x10
* NOTE: 0x00 => no-autoconfig => unspecified
*/
static const u8 lowpan_unc_llconf[] = {0x0f, 0x28, 0x22, 0x20};

/*
* Uncompression of ctx-based:
* 0 -> 0 bits from packet [unspecified / reserved]
* 1 -> 8 bytes from prefix - bunch of zeroes and 8 from packet
* 2 -> 8 bytes from prefix - zeroes + 2 from packet
* 3 -> 8 bytes from prefix - infer 8 bytes from lladdr
*/
static const u8 lowpan_unc_ctxconf[] = {0x00, 0x88, 0x82, 0x80};

/*
* Uncompression of ctx-base
* 0 -> 0 bits from packet
* 1 -> 2 bytes from prefix - bunch of zeroes 5 from packet
* 2 -> 2 bytes from prefix - zeroes + 3 from packet
* 3 -> 2 bytes from prefix - infer 1 bytes from lladdr
*/
static const u8 lowpan_unc_mxconf[] = {0x0f, 0x25, 0x23, 0x21};

/* Link local prefix */
static const u8 lowpan_llprefix[] = {0xfe, 0x80};

/* private device info */
struct lowpan_dev_info {
struct net_device *real_dev; /* real WPAN device ptr */
Expand Down Expand Up @@ -191,55 +158,177 @@ lowpan_compress_addr_64(u8 **hc06_ptr, u8 shift, const struct in6_addr *ipaddr,
return rol8(val, shift);
}

static void
lowpan_uip_ds6_set_addr_iid(struct in6_addr *ipaddr, unsigned char *lladdr)
/*
* Uncompress address function for source and
* destination address(non-multicast).
*
* address_mode is sam value or dam value.
*/
static int
lowpan_uncompress_addr(struct sk_buff *skb,
struct in6_addr *ipaddr,
const u8 address_mode,
const struct ieee802154_addr *lladdr)
{
memcpy(&ipaddr->s6_addr[8], lladdr, IEEE802154_ADDR_LEN);
/* second bit-flip (Universe/Local) is done according RFC2464 */
ipaddr->s6_addr[8] ^= 0x02;
bool fail;

switch (address_mode) {
case LOWPAN_IPHC_ADDR_00:
/* for global link addresses */
fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
break;
case LOWPAN_IPHC_ADDR_01:
/* fe:80::XXXX:XXXX:XXXX:XXXX */
ipaddr->s6_addr[0] = 0xFE;
ipaddr->s6_addr[1] = 0x80;
fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
break;
case LOWPAN_IPHC_ADDR_02:
/* fe:80::ff:fe00:XXXX */
ipaddr->s6_addr[0] = 0xFE;
ipaddr->s6_addr[1] = 0x80;
ipaddr->s6_addr[11] = 0xFF;
ipaddr->s6_addr[12] = 0xFE;
fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
break;
case LOWPAN_IPHC_ADDR_03:
fail = false;
switch (lladdr->addr_type) {
case IEEE802154_ADDR_LONG:
/* fe:80::XXXX:XXXX:XXXX:XXXX
* \_________________/
* hwaddr
*/
ipaddr->s6_addr[0] = 0xFE;
ipaddr->s6_addr[1] = 0x80;
memcpy(&ipaddr->s6_addr[8], lladdr->hwaddr,
IEEE802154_ADDR_LEN);
/* second bit-flip (Universe/Local)
* is done according RFC2464
*/
ipaddr->s6_addr[8] ^= 0x02;
break;
case IEEE802154_ADDR_SHORT:
/* fe:80::ff:fe00:XXXX
* \__/
* short_addr
*
* Universe/Local bit is zero.
*/
ipaddr->s6_addr[0] = 0xFE;
ipaddr->s6_addr[1] = 0x80;
ipaddr->s6_addr[11] = 0xFF;
ipaddr->s6_addr[12] = 0xFE;
ipaddr->s6_addr16[7] = htons(lladdr->short_addr);
break;
default:
pr_debug("Invalid addr_type set\n");
return -EINVAL;
}
break;
default:
pr_debug("Invalid address mode value: 0x%x\n", address_mode);
return -EINVAL;
}

if (fail) {
pr_debug("Failed to fetch skb data\n");
return -EIO;
}

lowpan_raw_dump_inline(NULL, "Reconstructed ipv6 addr is:\n",
ipaddr->s6_addr, 16);

return 0;
}

/*
* Uncompress addresses based on a prefix and a postfix with zeroes in
* between. If the postfix is zero in length it will use the link address
* to configure the IP address (autoconf style).
* pref_post_count takes a byte where the first nibble specify prefix count
* and the second postfix count (NOTE: 15/0xf => 16 bytes copy).
/* Uncompress address function for source context
* based address(non-multicast).
*/
static int
lowpan_uncompress_addr(struct sk_buff *skb, struct in6_addr *ipaddr,
u8 const *prefix, u8 pref_post_count, unsigned char *lladdr)
lowpan_uncompress_context_based_src_addr(struct sk_buff *skb,
struct in6_addr *ipaddr,
const u8 sam)
{
u8 prefcount = pref_post_count >> 4;
u8 postcount = pref_post_count & 0x0f;

/* full nibble 15 => 16 */
prefcount = (prefcount == 15 ? 16 : prefcount);
postcount = (postcount == 15 ? 16 : postcount);

if (lladdr)
lowpan_raw_dump_inline(__func__, "linklocal address",
lladdr, IEEE802154_ADDR_LEN);
if (prefcount > 0)
memcpy(ipaddr, prefix, prefcount);

if (prefcount + postcount < 16)
memset(&ipaddr->s6_addr[prefcount], 0,
16 - (prefcount + postcount));

if (postcount > 0) {
memcpy(&ipaddr->s6_addr[16 - postcount], skb->data, postcount);
skb_pull(skb, postcount);
} else if (prefcount > 0) {
if (lladdr == NULL)
return -EINVAL;
switch (sam) {
case LOWPAN_IPHC_ADDR_00:
/* unspec address ::
* Do nothing, address is already ::
*/
break;
case LOWPAN_IPHC_ADDR_01:
/* TODO */
case LOWPAN_IPHC_ADDR_02:
/* TODO */
case LOWPAN_IPHC_ADDR_03:
/* TODO */
netdev_warn(skb->dev, "SAM value 0x%x not supported\n", sam);
return -EINVAL;
default:
pr_debug("Invalid sam value: 0x%x\n", sam);
return -EINVAL;
}

lowpan_raw_dump_inline(NULL,
"Reconstructed context based ipv6 src addr is:\n",
ipaddr->s6_addr, 16);

return 0;
}

/* no IID based configuration if no prefix and no data */
lowpan_uip_ds6_set_addr_iid(ipaddr, lladdr);
/* Uncompress function for multicast destination address,
* when M bit is set.
*/
static int
lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
struct in6_addr *ipaddr,
const u8 dam)
{
bool fail;

switch (dam) {
case LOWPAN_IPHC_DAM_00:
/* 00: 128 bits. The full address
* is carried in-line.
*/
fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
break;
case LOWPAN_IPHC_DAM_01:
/* 01: 48 bits. The address takes
* the form ffXX::00XX:XXXX:XXXX.
*/
ipaddr->s6_addr[0] = 0xFF;
fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
break;
case LOWPAN_IPHC_DAM_10:
/* 10: 32 bits. The address takes
* the form ffXX::00XX:XXXX.
*/
ipaddr->s6_addr[0] = 0xFF;
fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
break;
case LOWPAN_IPHC_DAM_11:
/* 11: 8 bits. The address takes
* the form ff02::00XX.
*/
ipaddr->s6_addr[0] = 0xFF;
ipaddr->s6_addr[1] = 0x02;
fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
break;
default:
pr_debug("DAM value has a wrong value: 0x%x\n", dam);
return -EINVAL;
}

if (fail) {
pr_debug("Failed to fetch skb data\n");
return -EIO;
}

pr_debug("uncompressing %d + %d => ", prefcount, postcount);
lowpan_raw_dump_inline(NULL, NULL, ipaddr->s6_addr, 16);
lowpan_raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is:\n",
ipaddr->s6_addr, 16);

return 0;
}
Expand Down Expand Up @@ -702,6 +791,12 @@ lowpan_alloc_new_frame(struct sk_buff *skb, u16 len, u16 tag)
skb_reserve(frame->skb, sizeof(struct ipv6hdr));
skb_put(frame->skb, frame->length);

/* copy the first control block to keep a
* trace of the link-layer addresses in case
* of a link-local compressed address
*/
memcpy(frame->skb->cb, skb->cb, sizeof(skb->cb));

init_timer(&frame->timer);
/* time out is the same as for ipv6 - 60 sec */
frame->timer.expires = jiffies + LOWPAN_FRAG_TIMEOUT;
Expand All @@ -723,9 +818,9 @@ lowpan_alloc_new_frame(struct sk_buff *skb, u16 len, u16 tag)
static int
lowpan_process_data(struct sk_buff *skb)
{
struct ipv6hdr hdr;
struct ipv6hdr hdr = {};
u8 tmp, iphc0, iphc1, num_context = 0;
u8 *_saddr, *_daddr;
const struct ieee802154_addr *_saddr, *_daddr;
int err;

lowpan_raw_dump_table(__func__, "raw skb data dump", skb->data,
Expand Down Expand Up @@ -828,8 +923,8 @@ lowpan_process_data(struct sk_buff *skb)
if (lowpan_fetch_skb_u8(skb, &iphc1))
goto drop;

_saddr = mac_cb(skb)->sa.hwaddr;
_daddr = mac_cb(skb)->da.hwaddr;
_saddr = &mac_cb(skb)->sa;
_daddr = &mac_cb(skb)->da;

pr_debug("iphc0 = %02x, iphc1 = %02x\n", iphc0, iphc1);

Expand Down Expand Up @@ -868,8 +963,6 @@ lowpan_process_data(struct sk_buff *skb)

hdr.priority = ((tmp >> 2) & 0x0f);
hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
hdr.flow_lbl[1] = 0;
hdr.flow_lbl[2] = 0;
break;
/*
* Flow Label carried in-line
Expand All @@ -885,10 +978,6 @@ lowpan_process_data(struct sk_buff *skb)
break;
/* Traffic Class and Flow Label are elided */
case 3: /* 11b */
hdr.priority = 0;
hdr.flow_lbl[0] = 0;
hdr.flow_lbl[1] = 0;
hdr.flow_lbl[2] = 0;
break;
default:
break;
Expand All @@ -915,10 +1004,18 @@ lowpan_process_data(struct sk_buff *skb)
/* Extract SAM to the tmp variable */
tmp = ((iphc1 & LOWPAN_IPHC_SAM) >> LOWPAN_IPHC_SAM_BIT) & 0x03;

/* Source address uncompression */
pr_debug("source address stateless compression\n");
err = lowpan_uncompress_addr(skb, &hdr.saddr, lowpan_llprefix,
lowpan_unc_llconf[tmp], skb->data);
if (iphc1 & LOWPAN_IPHC_SAC) {
/* Source address context based uncompression */
pr_debug("SAC bit is set. Handle context based source address.\n");
err = lowpan_uncompress_context_based_src_addr(
skb, &hdr.saddr, tmp);
} else {
/* Source address uncompression */
pr_debug("source address stateless compression\n");
err = lowpan_uncompress_addr(skb, &hdr.saddr, tmp, _saddr);
}

/* Check on error of previous branch */
if (err)
goto drop;

Expand All @@ -931,23 +1028,14 @@ lowpan_process_data(struct sk_buff *skb)
pr_debug("dest: context-based mcast compression\n");
/* TODO: implement this */
} else {
u8 prefix[] = {0xff, 0x02};

pr_debug("dest: non context-based mcast compression\n");
if (0 < tmp && tmp < 3) {
if (lowpan_fetch_skb_u8(skb, &prefix[1]))
goto drop;
}

err = lowpan_uncompress_addr(skb, &hdr.daddr, prefix,
lowpan_unc_mxconf[tmp], NULL);
err = lowpan_uncompress_multicast_daddr(
skb, &hdr.daddr, tmp);
if (err)
goto drop;
}
} else {
pr_debug("dest: stateless compression\n");
err = lowpan_uncompress_addr(skb, &hdr.daddr, lowpan_llprefix,
lowpan_unc_llconf[tmp], skb->data);
err = lowpan_uncompress_addr(skb, &hdr.daddr, tmp, _daddr);
if (err)
goto drop;
}
Expand Down
20 changes: 17 additions & 3 deletions net/ieee802154/6lowpan.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -193,10 +193,12 @@
/* Values of fields within the IPHC encoding second byte */
#define LOWPAN_IPHC_CID 0x80

#define LOWPAN_IPHC_ADDR_00 0x00
#define LOWPAN_IPHC_ADDR_01 0x01
#define LOWPAN_IPHC_ADDR_02 0x02
#define LOWPAN_IPHC_ADDR_03 0x03

#define LOWPAN_IPHC_SAC 0x40
#define LOWPAN_IPHC_SAM_00 0x00
#define LOWPAN_IPHC_SAM_01 0x10
#define LOWPAN_IPHC_SAM_10 0x20
#define LOWPAN_IPHC_SAM 0x30

#define LOWPAN_IPHC_SAM_BIT 4
Expand Down Expand Up @@ -230,4 +232,16 @@
dest = 16 bit inline */
#define LOWPAN_NHC_UDP_CS_P_11 0xF3 /* source & dest = 0xF0B + 4bit inline */

static inline bool lowpan_fetch_skb(struct sk_buff *skb,
void *data, const unsigned int len)
{
if (unlikely(!pskb_may_pull(skb, len)))
return true;

skb_copy_from_linear_data(skb, data, len);
skb_pull(skb, len);

return false;
}

#endif /* __6LOWPAN_H__ */

0 comments on commit 15ec80f

Please sign in to comment.