netfilter: nf_log: fix direct userspace memory access in proc handler

Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index 2fefe147750a09b2f8d94f0e78f3b5f35e5b08b0..4e620305f28c765548c5c5b35b1a5b833034bf30 100644 (file)
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -47,7 +47,6 @@ int nf_log_register(u_int8_t pf, struct nf_logger *logger)
        mutex_lock(&nf_log_mutex);
 
        if (pf == NFPROTO_UNSPEC) {
-               int i;
                for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
                        list_add_tail(&(logger->list[i]), &(nf_loggers_l[i]));
        } else {
@@ -216,7 +215,7 @@ static const struct file_operations nflog_file_ops = {
 #endif /* PROC_FS */
 
 #ifdef CONFIG_SYSCTL
-struct ctl_path nf_log_sysctl_path[] = {
+static struct ctl_path nf_log_sysctl_path[] = {
        { .procname = "net", .ctl_name = CTL_NET, },
        { .procname = "netfilter", .ctl_name = NET_NETFILTER, },
        { .procname = "nf_log", .ctl_name = CTL_UNNUMBERED, },
@@ -228,19 +227,26 @@ static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 static struct ctl_table_header *nf_log_dir_header;
 
 static int nf_log_proc_dostring(ctl_table *table, int write, struct file *filp,
-                        void *buffer, size_t *lenp, loff_t *ppos)
+                        void __user *buffer, size_t *lenp, loff_t *ppos)
 {
        const struct nf_logger *logger;
+       char buf[NFLOGGER_NAME_LEN];
+       size_t size = *lenp;
        int r = 0;
        int tindex = (unsigned long)table->extra1;
 
        if (write) {
-               if (!strcmp(buffer, "NONE")) {
+               if (size > sizeof(buf))
+                       size = sizeof(buf);
+               if (copy_from_user(buf, buffer, size))
+                       return -EFAULT;
+
+               if (!strcmp(buf, "NONE")) {
                        nf_log_unbind_pf(tindex);
                        return 0;
                }
                mutex_lock(&nf_log_mutex);
-               logger = __find_logger(tindex, buffer);
+               logger = __find_logger(tindex, buf);
                if (logger == NULL) {
                        mutex_unlock(&nf_log_mutex);
                        return -ENOENT;