net: Fix sysctl restarts...

[ Upstream commit 88af182e389097997c5e2a0b42285b3522796759 ]

Yuck.  It turns out that when we restart sysctls we were restarting
with the values already changed.  Which unfortunately meant that
the second time through we thought there was no change and skipped
all kinds of work, despite the fact that there was indeed a change.

I have fixed this the simplest way possible by restoring the changed
values when we restart the sysctl write.

One of my coworkers spotted this bug when after disabling forwarding
on an interface pings were still forwarded.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 0030e73728e44fbfd9b35cbdec12a8b15782134c..cc35645d910ad24b78d4419e948a6ce56cf0613b 100644 (file)
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1351,14 +1351,19 @@ static int devinet_sysctl_forward(ctl_table *ctl, int write,
 {
        int *valp = ctl->data;
        int val = *valp;
+       loff_t pos = *ppos;
        int ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 
        if (write && *valp != val) {
                struct net *net = ctl->extra2;
 
                if (valp != &IPV4_DEVCONF_DFLT(net, FORWARDING)) {
-                       if (!rtnl_trylock())
+                       if (!rtnl_trylock()) {
+                               /* Restore the original values before restarting */
+                               *valp = val;
+                               *ppos = pos;
                                return restart_syscall();
+                       }
                        if (valp == &IPV4_DEVCONF_ALL(net, FORWARDING)) {
                                inet_forward_change(net);
                        } else if (*valp) {

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 1fd0a3d775d26767dec15c78f599dc96b1c3c08d..d1f77ccea28cafd75592b190bfc7afd1940b8840 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -504,8 +504,11 @@ static int addrconf_fixup_forwarding(struct ctl_table *table, int *p, int old)
        if (p == &net->ipv6.devconf_dflt->forwarding)
                return 0;
 
-       if (!rtnl_trylock())
+       if (!rtnl_trylock()) {
+               /* Restore the original values before restarting */
+               *p = old;
                return restart_syscall();
+       }
 
        if (p == &net->ipv6.devconf_all->forwarding) {
                __s32 newf = net->ipv6.devconf_all->forwarding;
@@ -3991,12 +3994,15 @@ int addrconf_sysctl_forward(ctl_table *ctl, int write,
 {
        int *valp = ctl->data;
        int val = *valp;
+       loff_t pos = *ppos;
        int ret;
 
        ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 
        if (write)
                ret = addrconf_fixup_forwarding(ctl, valp, val);
+       if (ret)
+               *ppos = pos;
        return ret;
 }
 
@@ -4075,8 +4081,11 @@ static int addrconf_disable_ipv6(struct ctl_table *table, int *p, int old)
        if (p == &net->ipv6.devconf_dflt->disable_ipv6)
                return 0;
 
-       if (!rtnl_trylock())
+       if (!rtnl_trylock()) {
+               /* Restore the original values before restarting */
+               *p = old;
                return restart_syscall();
+       }
 
        if (p == &net->ipv6.devconf_all->disable_ipv6) {
                __s32 newf = net->ipv6.devconf_all->disable_ipv6;
@@ -4095,12 +4104,15 @@ int addrconf_sysctl_disable(ctl_table *ctl, int write,
 {
        int *valp = ctl->data;
        int val = *valp;
+       loff_t pos = *ppos;
        int ret;
 
        ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 
        if (write)
                ret = addrconf_disable_ipv6(ctl, valp, val);
+       if (ret)
+               *ppos = pos;
        return ret;
 }