From: Florian Westphal <fw@xxxxxxxxx>
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@xxxxxxxxx>
Reported-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Reported-by: <syzbot+0502b00edac2a0680b61@xxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
include/linux/netfilter/x_tables.h | 2 ++
net/netfilter/x_tables.c | 30 ++++++++++++++++++++++++++++++
net/netfilter/xt_hashlimit.c | 16 ++++++++++------
net/netfilter/xt_recent.c | 6 +++---
4 files changed, 45 insertions(+), 9 deletions(-)
diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index 1313b35c3ab7..14529511c4b8 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -285,6 +285,8 @@ 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 fa1655aff8d3..4aa01c90e9d1 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -423,6 +423,36 @@ 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 66f5aca62a08..3360f13dc208 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -917,8 +917,9 @@ static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par)
struct hashlimit_cfg3 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);
@@ -935,8 +936,9 @@ static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par)
struct hashlimit_cfg3 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, 2);
@@ -950,9 +952,11 @@ static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par)
static int hashlimit_mt_check(const struct xt_mtchk_param *par)
{
struct xt_hashlimit_mtinfo3 *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, 3);
diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
index 6d232d18faff..81ee1d6543b2 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;
--
2.11.0
--
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