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net: reject Bootp/DHCP packets with bad OP value

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Rename check_packet to check_reply_packet to make its function more
obvious.
The check for DHCP_* values is completely off, as it should
compare against DHCP option 53 (Message Type). Only valid value for
any Bootp/DHCP reply is BOOTREPLY.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
This commit is contained in:
Stefan Brüns 2015-08-27 23:53:26 +02:00 committed by Joe Hershberger
parent 829533287a
commit 867d6ae2c9
1 changed files with 5 additions and 8 deletions
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13
net/bootp.c
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@ -109,7 +109,8 @@ static bool bootp_match_id(ulong id)
return false;
}
static int check_packet(uchar *pkt, unsigned dest, unsigned src, unsigned len)
static int check_reply_packet(uchar *pkt, unsigned dest, unsigned src,
unsigned len)
{
struct bootp_hdr *bp = (struct bootp_hdr *)pkt;
int retval = 0;
@ -118,11 +119,7 @@ static int check_packet(uchar *pkt, unsigned dest, unsigned src, unsigned len)
retval = -1;
else if (len < sizeof(struct bootp_hdr) - OPT_FIELD_SIZE)
retval = -2;
else if (bp->bp_op != OP_BOOTREQUEST &&
bp->bp_op != OP_BOOTREPLY &&
bp->bp_op != DHCP_OFFER &&
bp->bp_op != DHCP_ACK &&
bp->bp_op != DHCP_NAK)
else if (bp->bp_op != OP_BOOTREPLY)
retval = -3;
else if (bp->bp_htype != HWT_ETHER)
retval = -4;
@ -343,7 +340,7 @@ static void bootp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
bp = (struct bootp_hdr *)pkt;
/* Filter out pkts we don't want */
if (check_packet(pkt, dest, src, len))
if (check_reply_packet(pkt, dest, src, len))
return;
/*
@ -960,7 +957,7 @@ static void dhcp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
src, dest, len, dhcp_state);
/* Filter out pkts we don't want */
if (check_packet(pkt, dest, src, len))
if (check_reply_packet(pkt, dest, src, len))
return;
debug("DHCPHandler: got DHCP packet: (src=%d, dst=%d, len=%d) state: "