From: Chris Novakovic Date: Tue, 24 Apr 2018 02:56:35 +0000 (+0100) Subject: ipconfig: BOOTP: Request CONF_NAMESERVERS_MAX name servers X-Git-Tag: v4.18-rc1~114^2~397^2~4 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=de1fa15b6642f0b66f1844b9b464a8c28e84347c;p=linux.git 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, ยง3.8]), 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 Signed-off-by: David S. Miller --- diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c index bcf3c4f9882d..0f460d6d3cce 100644 --- a/net/ipv4/ipconfig.c +++ b/net/ipv4/ipconfig.c @@ -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;