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author | Maciej Żenczykowski <maze@google.com> | 2016-09-29 09:33:43 +0200 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2016-10-03 05:48:13 +0200 |
commit | cb9e684e89e69894cb6697a3fa1274a284d1d3bb (patch) | |
tree | a97bac16656d4489f010e8986e721c73e47f57ed /net/ipv6/addrconf.c | |
parent | netfilter: bridge: clarify bridge/netfilter message (diff) | |
download | linux-cb9e684e89e69894cb6697a3fa1274a284d1d3bb.tar.xz linux-cb9e684e89e69894cb6697a3fa1274a284d1d3bb.zip |
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/ipv6/addrconf.c')
-rw-r--r-- | net/ipv6/addrconf.c | 31 |
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); |