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[PATCH 4.6 12/81] ipv4: Fix non-initialized TTL when CONFIG_SYSCTL=n

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4.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>

[ Upstream commit 049bbf589ec651685205bd8ce73221fdd62345cf ]

Commit fa50d974d104 ("ipv4: Namespaceify ip_default_ttl sysctl knob")
moves the default TTL assignment, and as side-effect IPv4 TTL now
has a default value only if sysctl support is enabled (CONFIG_SYSCTL=y).

The sysctl_ip_default_ttl is fundamental for IP to work properly,
as it provides the TTL to be used as default. The defautl TTL may be
used in ip_selected_ttl, through the following flow:

  ip_select_ttl
    ip4_dst_hoplimit
      net->ipv4.sysctl_ip_default_ttl

This commit fixes the issue by assigning net->ipv4.sysctl_ip_default_ttl
in net_init_net, called during ipv4's initialization.

Without this commit, a kernel built without sysctl support will send
all IP packets with zero TTL (unless a TTL is explicitly set, e.g.
with setsockopt).

Given a similar issue might appear on the other knobs that were
namespaceify, this commit also moves them.

Fixes: fa50d974d104 ("ipv4: Namespaceify ip_default_ttl sysctl knob")
Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/af_inet.c         |    8 ++++++++
 net/ipv4/sysctl_net_ipv4.c |    4 ----
 2 files changed, 8 insertions(+), 4 deletions(-)

--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1660,6 +1660,14 @@ static __net_init int inet_init_net(stru
 	 */
 	net->ipv4.ping_group_range.range[0] = make_kgid(&init_user_ns, 1);
 	net->ipv4.ping_group_range.range[1] = make_kgid(&init_user_ns, 0);
+
+	/* Default values for sysctl-controlled parameters.
+	 * We set them here, in case sysctl is not compiled.
+	 */
+	net->ipv4.sysctl_ip_default_ttl = IPDEFTTL;
+	net->ipv4.sysctl_ip_dynaddr = 0;
+	net->ipv4.sysctl_ip_early_demux = 1;
+
 	return 0;
 }
 
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -988,10 +988,6 @@ static __net_init int ipv4_sysctl_init_n
 	if (!net->ipv4.sysctl_local_reserved_ports)
 		goto err_ports;
 
-	net->ipv4.sysctl_ip_default_ttl = IPDEFTTL;
-	net->ipv4.sysctl_ip_dynaddr = 0;
-	net->ipv4.sysctl_ip_early_demux = 1;
-
 	return 0;
 
 err_ports:

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[PATCH 4.6 00/81] 4.6.3-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 12/81] ipv4: Fix non-initialized TTL when CONFIG_SYSCTL=n Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 25/81] l2tp: fix configuration passed to setup_udp_tunnel_sock() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 40/81] gpiolib: Fix NULL pointer deference Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 27/81] KVM: arm/arm64: vgic-v2: Clear all dirty LRs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 13/81] bpf, inode: disallow userns mounts Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 45/81] crypto: public_key: select CRYPTO_AKCIPHER Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 09/81] bpf: Use mount_nodev not mount_ns to mount the bpf filesystem Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 19/81] net: stmmac: Fix incorrect memcpy source memory Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 23/81] tcp: record TLP and ER timer stats in v6 stats Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 02/81] scsi: Add QEMU CD-ROM to VPD Inquiry Blacklist Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 43/81] s390/bpf: reduce maximum program size to 64 KB Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 28/81] KVM: arm/arm64: vgic-v3: Clear all dirty LRs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 15/81] net: hwbm: Fix unbalanced spinlock in error case Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 08/81] tuntap: correctly wake up process during uninit Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 01:10 +0200
  [PATCH 4.6 00/87] 4.6.3-stable review -rc2 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-23 07:00 +0200
  Re: [PATCH 4.6 38/81] gpio: bail out silently on NULL descriptors Linus Walleij <linus.walleij@linaro.org> - 2016-06-23 09:30 +0200
    Re: [PATCH 4.6 38/81] gpio: bail out silently on NULL descriptors Hans de Goede <hdegoede@redhat.com> - 2016-06-23 11:20 +0200

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