From cb9e684e89e69894cb6697a3fa1274a284d1d3bb Mon Sep 17 00:00:00 2001 From: =?utf8?q?Maciej=20=C5=BBenczykowski?= Date: Thu, 29 Sep 2016 00:33:43 -0700 Subject: [PATCH] ipv6 addrconf: remove addrconf_sysctl_hop_limit() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Acked-by: Erik Kline Signed-off-by: David S. Miller --- net/ipv6/addrconf.c | 31 ++++++++++++++----------------- 1 file 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 @@ -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", @@ -6081,8 +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); -- 2.20.1