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authorMaciej Żenczykowski <maze@google.com>2016-09-29 00:33:43 -0700
committerDavid S. Miller <davem@davemloft.net>2016-10-02 23:48:13 -0400
commitcb9e684e89e69894cb6697a3fa1274a284d1d3bb (patch)
treea97bac16656d4489f010e8986e721c73e47f57ed /net
parentd4ef9f72128d414ad83b27b49312faa971d77382 (diff)
downloadlinux-cb9e684e89e69894cb6697a3fa1274a284d1d3bb.tar.bz2
ipv6 addrconf: remove addrconf_sysctl_hop_limit()
This is an effective no-op in terms of user observable behaviour. By preventing the overwrite of non-null extra1/extra2 fields in addrconf_sysctl() we can enable the use of proc_dointvec_minmax(). This allows us to eliminate the constant min/max (1..255) trampoline function that is addrconf_sysctl_hop_limit(). This is nice because it simplifies the code, and allows future sysctls with constant min/max limits to also not require trampolines. We still can't eliminate the trampoline for mtu because it isn't actually a constant (it depends on other tunables of the device) and thus requires at-write-time logic to enforce range. Signed-off-by: Maciej Żenczykowski <maze@google.com> Acked-by: Erik Kline <ek@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv6/addrconf.c31
1 files changed, 14 insertions, 17 deletions
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 87183983724d..cbd9343751a2 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -5497,20 +5497,6 @@ int addrconf_sysctl_forward(struct ctl_table *ctl, int write,
}
static
-int addrconf_sysctl_hop_limit(struct ctl_table *ctl, int write,
- void __user *buffer, size_t *lenp, loff_t *ppos)
-{
- struct ctl_table lctl;
- int min_hl = 1, max_hl = 255;
-
- lctl = *ctl;
- lctl.extra1 = &min_hl;
- lctl.extra2 = &max_hl;
-
- return proc_dointvec_minmax(&lctl, write, buffer, lenp, ppos);
-}
-
-static
int addrconf_sysctl_mtu(struct ctl_table *ctl, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
@@ -5743,6 +5729,9 @@ int addrconf_sysctl_ignore_routes_with_linkdown(struct ctl_table *ctl,
return ret;
}
+static const int one = 1;
+static const int two_five_five = 255;
+
static const struct ctl_table addrconf_sysctl[] = {
{
.procname = "forwarding",
@@ -5756,7 +5745,9 @@ static const struct ctl_table addrconf_sysctl[] = {
.data = &ipv6_devconf.hop_limit,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = addrconf_sysctl_hop_limit,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = (void *)&one,
+ .extra2 = (void *)&two_five_five,
},
{
.procname = "mtu",
@@ -6081,8 +6072,14 @@ static int __addrconf_sysctl_register(struct net *net, char *dev_name,
for (i = 0; table[i].data; i++) {
table[i].data += (char *)p - (char *)&ipv6_devconf;
- table[i].extra1 = idev; /* embedded; no ref */
- table[i].extra2 = net;
+ /* If one of these is already set, then it is not safe to
+ * overwrite either of them: this makes proc_dointvec_minmax
+ * usable.
+ */
+ if (!table[i].extra1 && !table[i].extra2) {
+ table[i].extra1 = idev; /* embedded; no ref */
+ table[i].extra2 = net;
+ }
}
snprintf(path, sizeof(path), "net/ipv6/conf/%s", dev_name);