path: root/net/ipv4/ipconfig.c
diff options
authorChris Novakovic <chris@chrisn.me.uk>2018-04-24 03:56:37 +0100
committerDavid S. Miller <davem@davemloft.net>2018-04-24 13:40:41 -0400
commit300eec7c0a2495f771709c7642aa15f7cc148b83 (patch)
tree92f29284c8b28bea58ea34e38a778e71015d27d1 /net/ipv4/ipconfig.c
parentipconfig: Document /proc/net/pnp (diff)
ipconfig: Correctly initialise ic_nameservers
ic_nameservers, which stores the list of name servers discovered by ipconfig, is initialised (i.e. has all of its elements set to NONE, or 0xffffffff) by ic_nameservers_predef() in the following scenarios: - before the "ip=" and "nfsaddrs=" kernel command line parameters are parsed (in ip_auto_config_setup()); - before autoconfiguring via DHCP or BOOTP (in ic_bootp_init()), in order to clear any values that may have been set after parsing "ip=" or "nfsaddrs=" and are no longer needed. This means that ic_nameservers_predef() is not called when neither "ip=" nor "nfsaddrs=" is specified on the kernel command line. In this scenario, every element in ic_nameservers remains set to 0x00000000, which is indistinguishable from ANY and causes pnp_seq_show() to write the following (bogus) information to /proc/net/pnp: #MANUAL nameserver nameserver nameserver This is potentially problematic for systems that blindly link /etc/resolv.conf to /proc/net/pnp. Ensure that ic_nameservers is also initialised when neither "ip=" nor "nfsaddrs=" are specified by calling ic_nameservers_predef() in ip_auto_config(), but only when ip_auto_config_setup() was not called earlier. This causes the following to be written to /proc/net/pnp, and is consistent with what gets written when ipconfig is configured manually but no name servers are specified on the kernel command line: #MANUAL Signed-off-by: Chris Novakovic <chris@chrisn.me.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ipconfig.c')
1 files changed, 13 insertions, 0 deletions
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index 0f460d6d3cce..e11dfd29a929 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -750,6 +750,11 @@ static void __init ic_bootp_init_ext(u8 *e)
static inline void __init ic_bootp_init(void)
+ /* Re-initialise all name servers to NONE, in case any were set via the
+ * "ip=" or "nfsaddrs=" kernel command line parameters: any IP addresses
+ * specified there will already have been decoded but are no longer
+ * needed
+ */
@@ -1370,6 +1375,13 @@ static int __init ip_auto_config(void)
int err;
unsigned int i;
+ /* Initialise all name servers to NONE (but only if the "ip=" or
+ * "nfsaddrs=" kernel command line parameters weren't decoded, otherwise
+ * we'll overwrite the IP addresses specified there)
+ */
+ if (ic_set_manually == 0)
+ ic_nameservers_predef();
proc_create("pnp", 0444, init_net.proc_net, &pnp_seq_fops);
#endif /* CONFIG_PROC_FS */
@@ -1593,6 +1605,7 @@ static int __init ip_auto_config_setup(char *addrs)
return 1;
+ /* Initialise all name servers to NONE */
/* Parse string for static IP assignment. */