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Provide individually cached constructed copies of DHCP packets via 

PXENV_GET_CACHED_INFO.  If we dont do this, Altiris' NBP screws up; it
relies on being able to grab pointers to each of the three packets and
then read them at will later.
This commit is contained in:
Michael Brown 2007-11-22 04:43:11 +00:00
parent 3a2473f123
commit 838ecba131
1 changed files with 109 additions and 86 deletions
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195
src/interface/pxe/pxe_preboot.c
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@ -32,22 +32,42 @@
#include <gpxe/netdevice.h> #include <gpxe/netdevice.h>
#include <gpxe/isapnp.h> #include <gpxe/isapnp.h>
#include <gpxe/init.h> #include <gpxe/init.h>
#include <gpxe/if_ether.h>
#include <basemem_packet.h> #include <basemem_packet.h>
#include "pxe.h" #include "pxe.h"
#include "pxe_call.h" #include "pxe_call.h"
/** Filename used for last TFTP request
*
* This is a bug-for-bug compatibility hack needed in order to work
* with Microsoft Remote Installation Services (RIS). The filename
* used in a call to PXENV_RESTART_TFTP must be returned as the DHCP
* filename in subsequent calls to PXENV_GET_CACHED_INFO.
*/
static char *pxe_ris_filename = NULL;
/* Avoid dragging in isapnp.o unnecessarily */ /* Avoid dragging in isapnp.o unnecessarily */
uint16_t isapnp_read_port; uint16_t isapnp_read_port;
/** Zero-based versions of PXENV_GET_CACHED_INFO::PacketType */
enum pxe_cached_info_indices {
CACHED_INFO_DHCPDISCOVER = ( PXENV_PACKET_TYPE_DHCP_DISCOVER - 1 ),
CACHED_INFO_DHCPACK = ( PXENV_PACKET_TYPE_DHCP_ACK - 1 ),
CACHED_INFO_BINL = ( PXENV_PACKET_TYPE_CACHED_REPLY - 1 ),
NUM_CACHED_INFOS
};
/** A cached DHCP packet */
union pxe_cached_info {
struct dhcphdr dhcphdr;
char raw[ETH_FRAME_LEN];
};
/* The case in which the caller doesn't supply a buffer is really
* awkward to support given that we have multiple sources of options,
* and that we don't actually store the DHCP packets. (We may not
* even have performed DHCP; we may have obtained all configuration
* from non-volatile stored options or from the command line.)
*
* Some NBPs rely on the buffers we provide being persistent, so we
* can't just use the temporary packet buffer. 4.5kB of base memory
* always wasted just because some clients are too lazy to provide
* their own buffers...
*/
static union pxe_cached_info __bss16_array ( cached_info, [NUM_CACHED_INFOS] );
#define cached_info __use_data16 ( cached_info )
/** /**
* UNLOAD BASE CODE STACK * UNLOAD BASE CODE STACK
* *
@ -72,8 +92,8 @@ PXENV_EXIT_t pxenv_get_cached_info ( struct s_PXENV_GET_CACHED_INFO
int ( * dhcp_packet_creator ) ( struct net_device *, int, int ( * dhcp_packet_creator ) ( struct net_device *, int,
struct dhcp_option_block *, void *, struct dhcp_option_block *, void *,
size_t, struct dhcp_packet * ); size_t, struct dhcp_packet * );
unsigned int idx;
unsigned int msgtype; unsigned int msgtype;
void *data = NULL;
size_t len; size_t len;
userptr_t buffer; userptr_t buffer;
int rc; int rc;
@ -83,88 +103,86 @@ PXENV_EXIT_t pxenv_get_cached_info ( struct s_PXENV_GET_CACHED_INFO
DBG ( " to %04x:%04x+%x", get_cached_info->Buffer.segment, DBG ( " to %04x:%04x+%x", get_cached_info->Buffer.segment,
get_cached_info->Buffer.offset, get_cached_info->BufferSize ); get_cached_info->Buffer.offset, get_cached_info->BufferSize );
/* The case in which the caller doesn't supply a buffer is /* Sanity check */
* really awkward to support given that we have multiple idx = ( get_cached_info->PacketType - 1 );
* sources of options, and that we don't actually store the if ( idx >= ( sizeof ( cached_info ) / sizeof ( cached_info[0] ) ) ) {
* DHCP packets. (We may not even have performed DHCP; we may DBG ( " bad PacketType" );
* have obtained all configuration from non-volatile stored goto err;
* options or from the command line.) We provide the caller }
* with our base-memory temporary packet buffer and construct
* the packet in there. /* Construct cached version of packet, if not already constructed. */
* if ( ! cached_info[idx].dhcphdr.op ) {
* To add to the fun, Intel decided at some point in the /* Construct DHCP packet */
* evolution of the PXE specification to add the BufferLimit if ( get_cached_info->PacketType ==
* field, which we are meant to fill in with the length of our PXENV_PACKET_TYPE_DHCP_DISCOVER ) {
* packet buffer, so that the caller can safely modify the dhcp_packet_creator = create_dhcp_request;
* boot server reply packet stored therein. However, this msgtype = DHCPDISCOVER;
* field was not present in earlier versions of the PXE spec, } else {
* and there is at least one PXE NBP (Altiris) which allocates dhcp_packet_creator = create_dhcp_response;
* only exactly enough space for this earlier, shorter version msgtype = DHCPACK;
* of the structure. If we actually fill in the BufferLimit }
* field, we therefore risk trashing random areas of the if ( ( rc = dhcp_packet_creator ( pxe_netdev, msgtype,
* caller's memory. If we *don't* fill it in, then the caller NULL, &cached_info[idx],
* is at liberty to assume that whatever random value happened sizeof ( cached_info[idx] ),
* to be in that location represents the length of the buffer &dhcppkt ) ) != 0 ) {
* we've just passed back to it. DBG ( " failed to build packet" );
* goto err;
* Since older PXE stacks won't fill this field in anyway, }
* it's probably safe to assume that no callers actually rely }
* on it, so we choose to not fill it in.
*/
len = get_cached_info->BufferSize; len = get_cached_info->BufferSize;
if ( len == 0 ) { if ( len == 0 ) {
len = sizeof ( basemem_packet ); /* Point client at our cached buffer.
*
* To add to the fun, Intel decided at some point in
* the evolution of the PXE specification to add the
* BufferLimit field, which we are meant to fill in
* with the length of our packet buffer, so that the
* caller can safely modify the boot server reply
* packet stored therein. However, this field was not
* present in earlier versions of the PXE spec, and
* there is at least one PXE NBP (Altiris) which
* allocates only exactly enough space for this
* earlier, shorter version of the structure. If we
* actually fill in the BufferLimit field, we
* therefore risk trashing random areas of the
* caller's memory. If we *don't* fill it in, then
* the caller is at liberty to assume that whatever
* random value happened to be in that location
* represents the length of the buffer we've just
* passed back to it.
*
* Since older PXE stacks won't fill this field in
* anyway, it's probably safe to assume that no
* callers actually rely on it, so we choose to not
* fill it in.
*/
get_cached_info->Buffer.segment = rm_ds; get_cached_info->Buffer.segment = rm_ds;
get_cached_info->Buffer.offset = get_cached_info->Buffer.offset =
( unsigned int ) ( & __from_data16 ( basemem_packet ) ); ( unsigned ) ( & __from_data16 ( cached_info[idx] ) );
DBG ( " using %04x:%04x+'%x'", get_cached_info->Buffer.segment, get_cached_info->BufferSize = sizeof ( cached_info[idx] );
DBG ( " returning %04x:%04x+%04x['%x']",
get_cached_info->Buffer.segment,
get_cached_info->Buffer.offset, get_cached_info->Buffer.offset,
get_cached_info->BufferSize,
get_cached_info->BufferLimit ); get_cached_info->BufferLimit );
}
/* Allocate space for temporary copy */
data = malloc ( len );
if ( ! data ) {
DBG ( " out of memory" );
goto err;
}
/* Construct DHCP packet */
if ( get_cached_info->PacketType == PXENV_PACKET_TYPE_DHCP_DISCOVER ) {
dhcp_packet_creator = create_dhcp_request;
msgtype = DHCPDISCOVER;
} else { } else {
dhcp_packet_creator = create_dhcp_response; /* Copy packet to client buffer */
msgtype = DHCPACK; if ( len < sizeof ( cached_info[idx] ) ) {
} DBG ( " buffer too short" );
if ( ( rc = dhcp_packet_creator ( pxe_netdev, msgtype, NULL, goto err;
data, len, &dhcppkt ) ) != 0 ) { }
DBG ( " failed to build packet" ); buffer = real_to_user ( get_cached_info->Buffer.segment,
goto err; get_cached_info->Buffer.offset );
copy_to_user ( buffer, 0, &cached_info[idx],
sizeof ( cached_info[idx] ) );
get_cached_info->BufferSize = sizeof ( cached_info[idx] );
} }
/* Overwrite filename to work around Microsoft RIS bug */
if ( pxe_ris_filename ) {
DBG ( " applying RIS hack" );
strncpy ( dhcppkt.dhcphdr->file, pxe_ris_filename,
sizeof ( dhcppkt.dhcphdr->file ) );
}
/* Copy packet to client buffer */
buffer = real_to_user ( get_cached_info->Buffer.segment,
get_cached_info->Buffer.offset );
len = dhcppkt.len;
DBG ( " length %x", len );
copy_to_user ( buffer, 0, data, len );
get_cached_info->BufferSize = len;
free ( data );
get_cached_info->Status = PXENV_STATUS_SUCCESS; get_cached_info->Status = PXENV_STATUS_SUCCESS;
return PXENV_EXIT_SUCCESS; return PXENV_EXIT_SUCCESS;
err: err:
if ( data )
free ( data );
get_cached_info->Status = PXENV_STATUS_OUT_OF_RESOURCES; get_cached_info->Status = PXENV_STATUS_OUT_OF_RESOURCES;
return PXENV_EXIT_FAILURE; return PXENV_EXIT_FAILURE;
} }
@ -179,13 +197,18 @@ PXENV_EXIT_t pxenv_restart_tftp ( struct s_PXENV_TFTP_READ_FILE
DBG ( "PXENV_RESTART_TFTP " ); DBG ( "PXENV_RESTART_TFTP " );
/* Work around Microsoft RIS bug */ /* This is a bug-for-bug compatibility hack needed in order to
free ( pxe_ris_filename ); * work with Microsoft Remote Installation Services (RIS).
pxe_ris_filename = strdup ( ( char * ) restart_tftp->FileName ); * The filename used in a call to PXENV_RESTART_TFTP must be
if ( ! pxe_ris_filename ) { * returned as the DHCP filename in subsequent calls to
restart_tftp->Status = PXENV_STATUS_OUT_OF_RESOURCES; * PXENV_GET_CACHED_INFO.
return PXENV_EXIT_FAILURE; */
} memcpy ( cached_info[CACHED_INFO_DHCPACK].dhcphdr.file,
restart_tftp->FileName,
sizeof ( cached_info[CACHED_INFO_DHCPACK].dhcphdr.file ) );
memcpy ( cached_info[CACHED_INFO_BINL].dhcphdr.file,
restart_tftp->FileName,
sizeof ( cached_info[CACHED_INFO_BINL].dhcphdr.file ) );
/* Words cannot describe the complete mismatch between the PXE /* Words cannot describe the complete mismatch between the PXE
* specification and any possible version of reality... * specification and any possible version of reality...