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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 12:12:50 +0200
commitc6ab7c6ceba551319e968e46d82f745d9ca1535a (patch)
tree88326a5c70dfc29977f1ec3fa318433d15f23f23 /net
parentccf38b31223edd9dd1852e43dafe347308629a46 (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>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/x_tables.c30
-rw-r--r--net/netfilter/xt_hashlimit.c11
-rw-r--r--net/netfilter/xt_recent.c6
3 files changed, 40 insertions, 7 deletions
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 7ad1a863587a..59be89813a29 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 b89b688e9d01..a1a29cdc58fc 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -794,8 +794,9 @@ static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
struct hashlimit_cfg2 cfg = {};
int ret;
- if (info->name[sizeof(info->name) - 1] != '\0')
- return -EINVAL;
+ ret = xt_check_proc_name(info->name, sizeof(info->name));
+ if (ret)
+ return ret;
ret = cfg_copy(&cfg, (void *)&info->cfg, 1);
@@ -809,9 +810,11 @@ static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
static int hashlimit_mt_check(const struct xt_mtchk_param *par)
{
struct xt_hashlimit_mtinfo2 *info = par->matchinfo;
+ int ret;
- if (info->name[sizeof(info->name) - 1] != '\0')
- return -EINVAL;
+ ret = xt_check_proc_name(info->name, sizeof(info->name));
+ if (ret)
+ return ret;
return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,
info->name, 2);
diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
index e3b7a09b103e..79d7ad621a80 100644
--- a/net/netfilter/xt_recent.c
+++ b/net/netfilter/xt_recent.c
@@ -361,9 +361,9 @@ static int recent_mt_check(const struct xt_mtchk_param *par,
info->hit_count, XT_RECENT_MAX_NSTAMPS - 1);
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;
if (ip_pkt_list_tot && info->hit_count < ip_pkt_list_tot)
nstamp_mask = roundup_pow_of_two(ip_pkt_list_tot) - 1;