Commit cb9e684e authored by Maciej Żenczykowski's avatar Maciej Żenczykowski Committed by David S. Miller
Browse files

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: default avatarMaciej Żenczykowski <maze@google.com>
Acked-by: default avatarErik Kline <ek@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d4ef9f72

net/ipv6/addrconf.c

+14 −17
Original line number Diff line number Diff line
@@ -5496,20 +5496,6 @@ int addrconf_sysctl_forward(struct ctl_table *ctl, int write, 
	return ret;

}



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",
@@ -6081,9 +6072,15 @@ 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;

		/* 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);

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