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netfilter: nf_log: fix error on write NONE to logger choice sysctl

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It is hard to unbind nf-logger:

  echo NONE > /proc/sys/net/netfilter/nf_log/0
  bash: echo: write error: No such file or directory

  sysctl -w net.netfilter.nf_log.0=NONE
  sysctl: setting key "net.netfilter.nf_log.0": No such file or directory
  net.netfilter.nf_log.0 = NONE

You need explicitly send '\0', for instance like:

  echo -e "NONE\0" > /proc/sys/net/netfilter/nf_log/0

That seem to be strange, so fix it using proc_dostring.

Now it works fine:
   modprobe nfnetlink_log
   echo nfnetlink_log > /proc/sys/net/netfilter/nf_log/0
   cat /proc/sys/net/netfilter/nf_log/0
   nfnetlink_log
   echo NONE > /proc/sys/net/netfilter/nf_log/0
   cat /proc/sys/net/netfilter/nf_log/0
   NONE

v2: add missed error check for proc_dostring

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pavel Tikhomirov 2016-07-01 16:53:54 +03:00 committed by Pablo Neira Ayuso
parent c37a2dfa67
commit c6ac37d8d8
1 changed files with 6 additions and 5 deletions
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11
net/netfilter/nf_log.c
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@ -418,16 +418,17 @@ static int nf_log_proc_dostring(struct ctl_table *table, int write,
{ {
const struct nf_logger *logger; const struct nf_logger *logger;
char buf[NFLOGGER_NAME_LEN]; char buf[NFLOGGER_NAME_LEN];
size_t size = *lenp;
int r = 0; int r = 0;
int tindex = (unsigned long)table->extra1; int tindex = (unsigned long)table->extra1;
struct net *net = current->nsproxy->net_ns; struct net *net = current->nsproxy->net_ns;
if (write) { if (write) {
if (size > sizeof(buf)) struct ctl_table tmp = *table;
size = sizeof(buf);
if (copy_from_user(buf, buffer, size)) tmp.data = buf;
return -EFAULT; r = proc_dostring(&tmp, write, buffer, lenp, ppos);
if (r)
return r;
if (!strcmp(buf, "NONE")) { if (!strcmp(buf, "NONE")) {
nf_log_unbind_pf(net, tindex); nf_log_unbind_pf(net, tindex);