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| author | Chris Novakovic <chris@chrisn.me.uk> | 2018-04-24 03:56:37 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-08-06 16:24:38 +0200 |
| commit | 0eb135eea738adae5bbe3a93b806576e20cd66f6 (patch) | |
| tree | 0f5d8147df25f0ac5fa069ba632f6d433a7cba3a | |
| parent | aa9190401a553e96edb4abe32b101d3e5c83f18f (diff) | |
ipconfig: Correctly initialise ic_nameservers
[ Upstream commit 300eec7c0a2495f771709c7642aa15f7cc148b83 ]
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 0.0.0.0
nameserver 0.0.0.0
nameserver 0.0.0.0
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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/ipv4/ipconfig.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c index 9d6b9c4c5f82..60f564db25a3 100644 --- a/net/ipv4/ipconfig.c +++ b/net/ipv4/ipconfig.c @@ -790,6 +790,11 @@ 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 + */ ic_nameservers_predef(); dev_add_pack(&bootp_packet_type); @@ -1423,6 +1428,13 @@ 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(); + #ifdef CONFIG_PROC_FS proc_create("pnp", S_IRUGO, init_net.proc_net, &pnp_seq_fops); #endif /* CONFIG_PROC_FS */ @@ -1640,6 +1652,7 @@ static int __init ip_auto_config_setup(char *addrs) return 1; } + /* Initialise all name servers to NONE */ ic_nameservers_predef(); /* Parse string for static IP assignment. */ |