diff options
Diffstat (limited to '0001-netfilter-xtables-zero-padding-in-data_to_user.patch')
| -rw-r--r-- | 0001-netfilter-xtables-zero-padding-in-data_to_user.patch | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/0001-netfilter-xtables-zero-padding-in-data_to_user.patch b/0001-netfilter-xtables-zero-padding-in-data_to_user.patch new file mode 100644 index 000000000..b23e387a6 --- /dev/null +++ b/0001-netfilter-xtables-zero-padding-in-data_to_user.patch @@ -0,0 +1,116 @@ +From b1a27013a72d5744be6510c05b86e1b9dd605012 Mon Sep 17 00:00:00 2001 +From: Willem de Bruijn <willemb@google.com> +Date: Tue, 9 May 2017 16:17:37 -0400 +Subject: [PATCH 1/2] netfilter: xtables: zero padding in data_to_user + +When looking up an iptables rule, the iptables binary compares the +aligned match and target data (XT_ALIGN). In some cases this can +exceed the actual data size to include padding bytes. + +Before commit f77bc5b23fb1 ("iptables: use match, target and data +copy_to_user helpers") the malloc()ed bytes were overwritten by the +kernel with kzalloced contents, zeroing the padding and making the +comparison succeed. After this patch, the kernel copies and clears +only data, leaving the padding bytes undefined. + +Extend the clear operation from data size to aligned data size to +include the padding bytes, if any. + +Padding bytes can be observed in both match and target, and the bug +triggered, by issuing a rule with match icmp and target ACCEPT: + + iptables -t mangle -A INPUT -i lo -p icmp --icmp-type 1 -j ACCEPT + iptables -t mangle -D INPUT -i lo -p icmp --icmp-type 1 -j ACCEPT + +Fixes: f77bc5b23fb1 ("iptables: use match, target and data copy_to_user helpers") +Reported-by: Paul Moore <pmoore@redhat.com> +Reported-by: Richard Guy Briggs <rgb@redhat.com> +Signed-off-by: Willem de Bruijn <willemb@google.com> +Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> +--- + include/linux/netfilter/x_tables.h | 2 +- + net/bridge/netfilter/ebtables.c | 9 ++++++--- + net/netfilter/x_tables.c | 9 ++++++--- + 3 files changed, 13 insertions(+), 7 deletions(-) + +diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h +index be378cf..b3044c2c 100644 +--- a/include/linux/netfilter/x_tables.h ++++ b/include/linux/netfilter/x_tables.h +@@ -294,7 +294,7 @@ int xt_match_to_user(const struct xt_entry_match *m, + int xt_target_to_user(const struct xt_entry_target *t, + struct xt_entry_target __user *u); + int xt_data_to_user(void __user *dst, const void *src, +- int usersize, int size); ++ int usersize, int size, int aligned_size); + + void *xt_copy_counters_from_user(const void __user *user, unsigned int len, + struct xt_counters_info *info, bool compat); +diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c +index 79b6991..656c259 100644 +--- a/net/bridge/netfilter/ebtables.c ++++ b/net/bridge/netfilter/ebtables.c +@@ -1358,7 +1358,8 @@ static inline int ebt_obj_to_user(char __user *um, const char *_name, + strlcpy(name, _name, sizeof(name)); + if (copy_to_user(um, name, EBT_FUNCTION_MAXNAMELEN) || + put_user(datasize, (int __user *)(um + EBT_FUNCTION_MAXNAMELEN)) || +- xt_data_to_user(um + entrysize, data, usersize, datasize)) ++ xt_data_to_user(um + entrysize, data, usersize, datasize, ++ XT_ALIGN(datasize))) + return -EFAULT; + + return 0; +@@ -1643,7 +1644,8 @@ static int compat_match_to_user(struct ebt_entry_match *m, void __user **dstptr, + if (match->compat_to_user(cm->data, m->data)) + return -EFAULT; + } else { +- if (xt_data_to_user(cm->data, m->data, match->usersize, msize)) ++ if (xt_data_to_user(cm->data, m->data, match->usersize, msize, ++ COMPAT_XT_ALIGN(msize))) + return -EFAULT; + } + +@@ -1672,7 +1674,8 @@ static int compat_target_to_user(struct ebt_entry_target *t, + if (target->compat_to_user(cm->data, t->data)) + return -EFAULT; + } else { +- if (xt_data_to_user(cm->data, t->data, target->usersize, tsize)) ++ if (xt_data_to_user(cm->data, t->data, target->usersize, tsize, ++ COMPAT_XT_ALIGN(tsize))) + return -EFAULT; + } + +diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c +index 14857af..afb02fd 100644 +--- a/net/netfilter/x_tables.c ++++ b/net/netfilter/x_tables.c +@@ -283,12 +283,13 @@ static int xt_obj_to_user(u16 __user *psize, u16 size, + &U->u.user.revision, K->u.kernel.TYPE->revision) + + int xt_data_to_user(void __user *dst, const void *src, +- int usersize, int size) ++ int usersize, int size, int aligned_size) + { + usersize = usersize ? : size; + if (copy_to_user(dst, src, usersize)) + return -EFAULT; +- if (usersize != size && clear_user(dst + usersize, size - usersize)) ++ if (usersize != aligned_size && ++ clear_user(dst + usersize, aligned_size - usersize)) + return -EFAULT; + + return 0; +@@ -298,7 +299,9 @@ EXPORT_SYMBOL_GPL(xt_data_to_user); + #define XT_DATA_TO_USER(U, K, TYPE, C_SIZE) \ + xt_data_to_user(U->data, K->data, \ + K->u.kernel.TYPE->usersize, \ +- C_SIZE ? : K->u.kernel.TYPE->TYPE##size) ++ C_SIZE ? : K->u.kernel.TYPE->TYPE##size, \ ++ C_SIZE ? COMPAT_XT_ALIGN(C_SIZE) : \ ++ XT_ALIGN(K->u.kernel.TYPE->TYPE##size)) + + int xt_match_to_user(const struct xt_entry_match *m, + struct xt_entry_match __user *u) +-- +2.7.5 + |