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authorFlorian Westphal <fw@strlen.de>2018-03-10 01:15:45 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-04-08 11:49:45 +0200
commit42b41149e2459edb50d583ac732b4941d898bae8 (patch)
treedad574a830c16b24305e1d6d314744a256391f4c
parent63d1e53df8de96085e423a973bb557d6d6b350f3 (diff)
netfilter: x_tables: add and use xt_check_proc_name
commit b1d0a5d0cba4597c0394997b2d5fced3e3841b4e upstream. recent and hashlimit both create /proc files, but only check that name is 0 terminated. This can trigger WARN() from procfs when name is "" or "/". Add helper for this and then use it for both. Cc: Eric Dumazet <eric.dumazet@gmail.com> Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Reported-by: <syzbot+0502b00edac2a0680b61@syzkaller.appspotmail.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/linux/netfilter/x_tables.h2
-rw-r--r--net/netfilter/x_tables.c30
-rw-r--r--net/netfilter/xt_hashlimit.c5
-rw-r--r--net/netfilter/xt_recent.c6
4 files changed, 38 insertions, 5 deletions
diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index cc615e273f80..b95f00cb6219 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -247,6 +247,8 @@ unsigned int *xt_alloc_entry_offsets(unsigned int size);
bool xt_find_jump_offset(const unsigned int *offsets,
unsigned int target, unsigned int size);
+int xt_check_proc_name(const char *name, unsigned int size);
+
int xt_check_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto,
bool inv_proto);
int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto,
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index dfba682a92f6..ede118a0d6b0 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -367,6 +367,36 @@ textify_hooks(char *buf, size_t size, unsigned int mask, uint8_t nfproto)
return buf;
}
+/**
+ * xt_check_proc_name - check that name is suitable for /proc file creation
+ *
+ * @name: file name candidate
+ * @size: length of buffer
+ *
+ * some x_tables modules wish to create a file in /proc.
+ * This function makes sure that the name is suitable for this
+ * purpose, it checks that name is NUL terminated and isn't a 'special'
+ * name, like "..".
+ *
+ * returns negative number on error or 0 if name is useable.
+ */
+int xt_check_proc_name(const char *name, unsigned int size)
+{
+ if (name[0] == '\0')
+ return -EINVAL;
+
+ if (strnlen(name, size) == size)
+ return -ENAMETOOLONG;
+
+ if (strcmp(name, ".") == 0 ||
+ strcmp(name, "..") == 0 ||
+ strchr(name, '/'))
+ return -EINVAL;
+
+ return 0;
+}
+EXPORT_SYMBOL(xt_check_proc_name);
+
int xt_check_match(struct xt_mtchk_param *par,
unsigned int size, u_int8_t proto, bool inv_proto)
{
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index 05fbc2a0be46..1667ebbb4a0e 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -668,8 +668,9 @@ static int hashlimit_mt_check(const struct xt_mtchk_param *par)
if (info->cfg.gc_interval == 0 || info->cfg.expire == 0)
return -EINVAL;
- if (info->name[sizeof(info->name)-1] != '\0')
- return -EINVAL;
+ ret = xt_check_proc_name(info->name, sizeof(info->name));
+ if (ret)
+ return ret;
if (par->family == NFPROTO_IPV4) {
if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32)
return -EINVAL;
diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
index a9faae89f955..e0228d23ceae 100644
--- a/net/netfilter/xt_recent.c
+++ b/net/netfilter/xt_recent.c
@@ -355,9 +355,9 @@ static int recent_mt_check(const struct xt_mtchk_param *par,
info->hit_count, ip_pkt_list_tot);
return -EINVAL;
}
- if (info->name[0] == '\0' ||
- strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN)
- return -EINVAL;
+ ret = xt_check_proc_name(info->name, sizeof(info->name));
+ if (ret)
+ return ret;
mutex_lock(&recent_mutex);
t = recent_table_lookup(recent_net, info->name);