Commit de1fa15b authored Apr 24, 2018 by Chris Novakovic Committed by David S. Miller Apr 24, 2018

ipconfig: BOOTP: Request CONF_NAMESERVERS_MAX name servers

When ipconfig is autoconfigured via BOOTP, the request packet
initialised by ic_bootp_init_ext() always allocates 8 bytes for the name
server option, limiting the BOOTP server to responding with at most 2
name servers even though ipconfig in fact supports an arbitrary number
of name servers (as defined by CONF_NAMESERVERS_MAX, which is currently
3).

Only request name servers in the request packet if CONF_NAMESERVERS_MAX
is positive (to comply with [1, §3.8]), and allocate enough space in the
packet for CONF_NAMESERVERS_MAX name servers to indicate the maximum
number we can accept in response.

[1] RFC 2132, "DHCP Options and BOOTP Vendor Extensions":
    https://tools.ietf.org/rfc/rfc2132.txt



Signed-off-by: Chris Novakovic <chris@chrisn.me.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 4e1a8af2

net/ipv4/ipconfig.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -721,9 +721,11 @@ static void __init ic_bootp_init_ext(u8 *e)
		e++ = 3; / Default gateway request */
		*e++ = 4;
		e += 4;
		#if CONF_NAMESERVERS_MAX > 0
		e++ = 6; / (DNS) name server request */
		*e++ = 8;
		e += 8;
		e++ = 4 CONF_NAMESERVERS_MAX;
		e += 4 * CONF_NAMESERVERS_MAX;
		#endif
		e++ = 12; / Host name request */
		*e++ = 32;
		e += 32;

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