mirror of https://github.com/ipxe/ipxe.git
[ipv4] Fix fragment reassembly
Signed-off-by: Michael Brown <mcb30@ipxe.org>pull/5/head
Michael Brown
parent
17f09dfe03
commit
13186b64b6
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@ -31,9 +31,6 @@ struct io_buffer;
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#define IP_TOS 0
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#define IP_TTL 64
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#define IP_FRAG_IOB_SIZE 1500
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#define IP_FRAG_TIMEOUT 50
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/** An IPv4 packet header */
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struct iphdr {
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uint8_t verhdrlen;
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@ -73,20 +70,16 @@ struct ipv4_miniroute {
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struct in_addr gateway;
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};
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/* Fragment reassembly buffer */
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struct frag_buffer {
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/* Identification number */
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uint16_t ident;
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/* Source network address */
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struct in_addr src;
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/* Destination network address */
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struct in_addr dest;
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/* Reassembled I/O buffer */
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struct io_buffer *frag_iob;
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/* Reassembly timer */
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struct retry_timer frag_timer;
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/* IPv4 fragment reassembly buffer */
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struct ipv4_fragment {
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/* List of fragment reassembly buffers */
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struct list_head list;
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/** Reassembled packet */
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struct io_buffer *iobuf;
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/** Current offset */
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size_t offset;
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/** Reassembly timer */
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struct retry_timer timer;
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};
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extern struct list_head ipv4_miniroutes;
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208
src/net/ipv4.c
208
src/net/ipv4.c
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@ -14,6 +14,7 @@
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#include <ipxe/tcpip.h>
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#include <ipxe/dhcp.h>
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#include <ipxe/settings.h>
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#include <ipxe/timer.h>
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/** @file
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*
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@ -30,7 +31,10 @@ static uint8_t next_ident_high = 0;
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struct list_head ipv4_miniroutes = LIST_HEAD_INIT ( ipv4_miniroutes );
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/** List of fragment reassembly buffers */
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static LIST_HEAD ( frag_buffers );
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static LIST_HEAD ( ipv4_fragments );
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/** Fragment reassembly timeout */
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#define IP_FRAG_TIMEOUT ( TICKS_PER_SEC / 2 )
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/**
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* Add IPv4 minirouting table entry
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@ -128,103 +132,126 @@ static struct ipv4_miniroute * ipv4_route ( struct in_addr *dest ) {
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}
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/**
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* Fragment reassembly counter timeout
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* Expire fragment reassembly buffer
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*
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* @v timer Retry timer
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* @v over If asserted, the timer is greater than @c MAX_TIMEOUT
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* @v timer Retry timer
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* @v fail Failure indicator
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*/
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static void ipv4_frag_expired ( struct retry_timer *timer __unused,
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int over ) {
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if ( over ) {
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DBG ( "Fragment reassembly timeout" );
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/* Free the fragment buffer */
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}
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static void ipv4_fragment_expired ( struct retry_timer *timer,
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int fail __unused ) {
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struct ipv4_fragment *frag =
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container_of ( timer, struct ipv4_fragment, timer );
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struct iphdr *iphdr = frag->iobuf->data;
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DBG ( "IPv4 fragment %04x expired\n", ntohs ( iphdr->ident ) );
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free_iob ( frag->iobuf );
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list_del ( &frag->list );
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free ( frag );
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}
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/**
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* Free fragment buffer
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* Find matching fragment reassembly buffer
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*
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* @v fragbug Fragment buffer
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* @v iphdr IPv4 header
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* @ret frag Fragment reassembly buffer, or NULL
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*/
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static void free_fragbuf ( struct frag_buffer *fragbuf ) {
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free ( fragbuf );
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static struct ipv4_fragment * ipv4_fragment ( struct iphdr *iphdr ) {
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struct ipv4_fragment *frag;
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struct iphdr *frag_iphdr;
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list_for_each_entry ( frag, &ipv4_fragments, list ) {
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frag_iphdr = frag->iobuf->data;
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if ( ( iphdr->src.s_addr == frag_iphdr->src.s_addr ) &&
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( iphdr->ident == frag_iphdr->ident ) ) {
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return frag;
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}
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}
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return NULL;
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}
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/**
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* Fragment reassembler
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*
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* @v iobuf I/O buffer, fragment of the datagram
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* @ret frag_iob Reassembled packet, or NULL
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* @v iobuf I/O buffer
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* @ret iobuf Reassembled packet, or NULL
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*/
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static struct io_buffer * ipv4_reassemble ( struct io_buffer * iobuf ) {
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static struct io_buffer * ipv4_reassemble ( struct io_buffer *iobuf ) {
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struct iphdr *iphdr = iobuf->data;
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struct frag_buffer *fragbuf;
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/**
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* Check if the fragment belongs to any fragment series
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*/
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list_for_each_entry ( fragbuf, &frag_buffers, list ) {
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if ( fragbuf->ident == iphdr->ident &&
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fragbuf->src.s_addr == iphdr->src.s_addr ) {
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/**
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* Check if the packet is the expected fragment
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*
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* The offset of the new packet must be equal to the
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* length of the data accumulated so far (the length of
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* the reassembled I/O buffer
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*/
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if ( iob_len ( fragbuf->frag_iob ) ==
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( iphdr->frags & IP_MASK_OFFSET ) ) {
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/**
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* Append the contents of the fragment to the
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* reassembled I/O buffer
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*/
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iob_pull ( iobuf, sizeof ( *iphdr ) );
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memcpy ( iob_put ( fragbuf->frag_iob,
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iob_len ( iobuf ) ),
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iobuf->data, iob_len ( iobuf ) );
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free_iob ( iobuf );
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size_t offset = ( ( ntohs ( iphdr->frags ) & IP_MASK_OFFSET ) << 3 );
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unsigned int more_frags = ( iphdr->frags & htons ( IP_MASK_MOREFRAGS ));
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size_t hdrlen = ( ( iphdr->verhdrlen & IP_MASK_HLEN ) * 4 );
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struct ipv4_fragment *frag;
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size_t expected_offset;
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struct io_buffer *new_iobuf;
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/** Check if the fragment series is over */
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if ( ! ( iphdr->frags & IP_MASK_MOREFRAGS ) ) {
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iobuf = fragbuf->frag_iob;
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free_fragbuf ( fragbuf );
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return iobuf;
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}
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/* Find matching fragment reassembly buffer, if any */
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frag = ipv4_fragment ( iphdr );
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} else {
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/* Discard the fragment series */
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free_fragbuf ( fragbuf );
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free_iob ( iobuf );
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}
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return NULL;
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/* Drop out-of-order fragments */
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expected_offset = ( frag ? frag->offset : 0 );
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if ( offset != expected_offset ) {
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DBG ( "IPv4 dropping out-of-sequence fragment %04x (%zd+%zd, "
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"expected %zd)\n", ntohs ( iphdr->ident ), offset,
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( iob_len ( iobuf ) - hdrlen ), expected_offset );
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goto drop;
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}
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/* Create or extend fragment reassembly buffer as applicable */
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if ( frag == NULL ) {
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/* Create new fragment reassembly buffer */
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frag = zalloc ( sizeof ( *frag ) );
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if ( ! frag )
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goto drop;
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list_add ( &frag->list, &ipv4_fragments );
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frag->iobuf = iobuf;
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frag->offset = ( iob_len ( iobuf ) - hdrlen );
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timer_init ( &frag->timer, ipv4_fragment_expired, NULL );
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} else {
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/* Extend reassembly buffer */
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iob_pull ( iobuf, hdrlen );
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new_iobuf = alloc_iob ( iob_len ( frag->iobuf ) +
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iob_len ( iobuf ) );
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if ( ! new_iobuf ) {
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DBG ( "IPv4 could not extend reassembly buffer to "
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"%zd bytes\n",
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( iob_len ( frag->iobuf ) + iob_len ( iobuf ) ) );
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goto drop;
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}
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memcpy ( iob_put ( new_iobuf, iob_len ( frag->iobuf ) ),
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frag->iobuf->data, iob_len ( frag->iobuf ) );
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memcpy ( iob_put ( new_iobuf, iob_len ( iobuf ) ),
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iobuf->data, iob_len ( iobuf ) );
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free_iob ( frag->iobuf );
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frag->iobuf = new_iobuf;
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frag->offset += iob_len ( iobuf );
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free_iob ( iobuf );
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iphdr = frag->iobuf->data;
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iphdr->len = ntohs ( iob_len ( frag->iobuf ) );
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/* Stop fragment reassembly timer */
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stop_timer ( &frag->timer );
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/* If this is the final fragment, return it */
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if ( ! more_frags ) {
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iobuf = frag->iobuf;
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list_del ( &frag->list );
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free ( frag );
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return iobuf;
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}
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}
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/** Check if the fragment is the first in the fragment series */
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if ( iphdr->frags & IP_MASK_MOREFRAGS &&
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( ( iphdr->frags & IP_MASK_OFFSET ) == 0 ) ) {
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/** Create a new fragment buffer */
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fragbuf = ( struct frag_buffer* ) malloc ( sizeof( *fragbuf ) );
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fragbuf->ident = iphdr->ident;
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fragbuf->src = iphdr->src;
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/* Set up the reassembly I/O buffer */
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fragbuf->frag_iob = alloc_iob ( IP_FRAG_IOB_SIZE );
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iob_pull ( iobuf, sizeof ( *iphdr ) );
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memcpy ( iob_put ( fragbuf->frag_iob, iob_len ( iobuf ) ),
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iobuf->data, iob_len ( iobuf ) );
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free_iob ( iobuf );
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/* (Re)start fragment reassembly timer */
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start_timer_fixed ( &frag->timer, IP_FRAG_TIMEOUT );
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/* Set the reassembly timer */
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timer_init ( &fragbuf->frag_timer, ipv4_frag_expired, NULL );
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start_timer_fixed ( &fragbuf->frag_timer, IP_FRAG_TIMEOUT );
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return NULL;
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/* Add the fragment buffer to the list of fragment buffers */
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list_add ( &fragbuf->list, &frag_buffers );
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}
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drop:
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free_iob ( iobuf );
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return NULL;
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}
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@ -481,6 +508,9 @@ static int ipv4_rx ( struct io_buffer *iobuf,
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goto err;
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}
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/* Truncate packet to correct length */
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iob_unput ( iobuf, ( iob_len ( iobuf ) - len ) );
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/* Print IPv4 header for debugging */
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DBG ( "IPv4 RX %s<-", inet_ntoa ( iphdr->dest ) );
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DBG ( "%s len %d proto %d id %04x csum %04x\n",
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@ -496,31 +526,29 @@ static int ipv4_rx ( struct io_buffer *iobuf,
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goto err;
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}
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/* Truncate packet to correct length, calculate pseudo-header
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* checksum and then strip off the IPv4 header.
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*/
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iob_unput ( iobuf, ( iob_len ( iobuf ) - len ) );
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pshdr_csum = ipv4_pshdr_chksum ( iobuf, TCPIP_EMPTY_CSUM );
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iob_pull ( iobuf, hdrlen );
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/* Fragment reassembly */
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if ( ( iphdr->frags & htons ( IP_MASK_MOREFRAGS ) ) ||
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( ( iphdr->frags & htons ( IP_MASK_OFFSET ) ) != 0 ) ) {
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/* Pass the fragment to ipv4_reassemble() which either
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* returns a fully reassembled I/O buffer or NULL.
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/* Perform fragment reassembly if applicable */
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if ( iphdr->frags & htons ( IP_MASK_OFFSET | IP_MASK_MOREFRAGS ) ) {
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/* Pass the fragment to ipv4_reassemble() which returns
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* either a fully reassembled I/O buffer or NULL.
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*/
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iobuf = ipv4_reassemble ( iobuf );
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if ( ! iobuf )
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return 0;
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iphdr = iobuf->data;
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hdrlen = ( ( iphdr->verhdrlen & IP_MASK_HLEN ) * 4 );
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}
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/* Construct socket addresses and hand off to transport layer */
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/* Construct socket addresses, calculate pseudo-header
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* checksum, and hand off to transport layer
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*/
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memset ( &src, 0, sizeof ( src ) );
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src.sin.sin_family = AF_INET;
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src.sin.sin_addr = iphdr->src;
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memset ( &dest, 0, sizeof ( dest ) );
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dest.sin.sin_family = AF_INET;
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dest.sin.sin_addr = iphdr->dest;
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pshdr_csum = ipv4_pshdr_chksum ( iobuf, TCPIP_EMPTY_CSUM );
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iob_pull ( iobuf, hdrlen );
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if ( ( rc = tcpip_rx ( iobuf, iphdr->protocol, &src.st,
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&dest.st, pshdr_csum ) ) != 0 ) {
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DBG ( "IPv4 received packet rejected by stack: %s\n",
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