libubox: backport security patches

This backports some security relevant patches from libubox master. These
patches should not change the existing API and ABI so that old
applications still work like before without any recompilation.
Application can now also use more secure APIs.

The new more secure interfaces are also available, but not used.

OpenWrt master and 19.07 already have these patches by using a more
recent libubox version.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

1 files changed, 157 insertions, 0 deletions

diff --git a/package/libs/libubox/patches/0009-blobmsg-add-_len-variants-for-all-attribute-checking.patch b/package/libs/libubox/patches/0009-blobmsg-add-_len-variants-for-all-attribute-checking.patch
new file mode 100644
index 0000000000..7f90df1638
--- /dev/null
+++ b/package/libs/libubox/patches/0009-blobmsg-add-_len-variants-for-all-attribute-checking.patch
@@ -0,0 +1,157 @@
+From ad29d0304983e283d4aec4ee5462942eaf5c03ac Mon Sep 17 00:00:00 2001
+From: Tobias Schramm <tobleminer@gmail.com>
+Date: Thu, 15 Nov 2018 03:42:48 +0100
+Subject: blobmsg: add _len variants for all attribute checking methods
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Introduce _len variants of blobmsg attribute checking functions which
+aims to provide safer implementation as those functions should limit all
+memory accesses performed on the blob to the range [attr, attr + len]
+(upper bound non inclusive) and thus should be suited for checking of
+untrusted blob attributes.
+
+While at it add some comments in order to make it clear.
+
+Signed-off-by: Tobias Schramm <tobleminer@gmail.com>
+[_safe -> _len, blobmsg_check_array_len fix, commit subject/desc facelift]
+Signed-off-by: Petr Štetiar <ynezz@true.cz>
+---
+ blobmsg.c | 21 ++++++++++++++++++---
+ blobmsg.h | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
+ 2 files changed, 72 insertions(+), 4 deletions(-)
+
+--- a/blobmsg.c
++++ b/blobmsg.c
+@@ -101,11 +101,21 @@ bool blobmsg_check_attr_len(const struct
+ 
+ int blobmsg_check_array(const struct blob_attr *attr, int type)
+ {
++	return blobmsg_check_array_len(attr, type, blob_raw_len(attr));
++}
++
++int blobmsg_check_array_len(const struct blob_attr *attr, int type, size_t len)
++{
+ 	struct blob_attr *cur;
+ 	bool name;
+-	int rem;
+ 	int size = 0;
+ 
++	if (type > BLOBMSG_TYPE_LAST)
++		return -1;
++
++	if (!blobmsg_check_attr_len(attr, false, len))
++		return -1;
++
+ 	switch (blobmsg_type(attr)) {
+ 	case BLOBMSG_TYPE_TABLE:
+ 		name = true;
+@@ -117,11 +127,11 @@ int blobmsg_check_array(const struct blo
+ 		return -1;
+ 	}
+ 
+-	blobmsg_for_each_attr(cur, attr, rem) {
++	__blobmsg_for_each_attr(cur, attr, len) {
+ 		if (type != BLOBMSG_TYPE_UNSPEC && blobmsg_type(cur) != type)
+ 			return -1;
+ 
+-		if (!blobmsg_check_attr(cur, name))
++		if (!blobmsg_check_attr_len(cur, name, len))
+ 			return -1;
+ 
+ 		size++;
+@@ -135,6 +145,11 @@ bool blobmsg_check_attr_list(const struc
+ 	return blobmsg_check_array(attr, type) >= 0;
+ }
+ 
++bool blobmsg_check_attr_list_len(const struct blob_attr *attr, int type, size_t len)
++{
++	return blobmsg_check_array_len(attr, type, len) >= 0;
++}
++
+ int blobmsg_parse_array(const struct blobmsg_policy *policy, int policy_len,
+ 			struct blob_attr **tb, void *data, unsigned int len)
+ {
+--- a/blobmsg.h
++++ b/blobmsg.h
+@@ -104,19 +104,66 @@ static inline int blobmsg_len(const stru
+ 	return blobmsg_data_len(attr);
+ }
+ 
++/*
++ * blobmsg_check_attr: validate a list of attributes
++ *
++ * This method may be used with trusted data only. Providing
++ * malformed blobs will cause out of bounds memory access.
++ */
+ bool blobmsg_check_attr(const struct blob_attr *attr, bool name);
+-bool blobmsg_check_attr_list(const struct blob_attr *attr, int type);
+ 
++/*
++ * blobmsg_check_attr_len: validate a list of attributes
++ *
++ * This method should be safer implementation of blobmsg_check_attr.
++ * It will limit all memory access performed on the blob to the
++ * range [attr, attr + len] (upper bound non inclusive) and is
++ * thus suited for checking of untrusted blob attributes.
++ */
+ bool blobmsg_check_attr_len(const struct blob_attr *attr, bool name, size_t len);
+ 
+ /*
++ * blobmsg_check_attr_list: validate a list of attributes
++ *
++ * This method may be used with trusted data only. Providing
++ * malformed blobs will cause out of bounds memory access.
++ */
++bool blobmsg_check_attr_list(const struct blob_attr *attr, int type);
++
++/*
++ * blobmsg_check_attr_list_len: validate a list of untrusted attributes
++ *
++ * This method should be safer implementation of blobmsg_check_attr_list.
++ * It will limit all memory access performed on the blob to the
++ * range [attr, attr + len] (upper bound non inclusive) and is
++ * thus suited for checking of untrusted blob attributes.
++ */
++bool blobmsg_check_attr_list_len(const struct blob_attr *attr, int type, size_t len);
++
++/*
+  * blobmsg_check_array: validate array/table and return size
+  *
+  * Checks if all elements of an array or table are valid and have
+  * the specified type. Returns the number of elements in the array
++ *
++ * This method may be used with trusted data only. Providing
++ * malformed blobs will cause out of bounds memory access.
+  */
+ int blobmsg_check_array(const struct blob_attr *attr, int type);
+ 
++/*
++ * blobmsg_check_array_len: validate untrusted array/table and return size
++ *
++ * Checks if all elements of an array or table are valid and have
++ * the specified type. Returns the number of elements in the array.
++ *
++ * This method should be safer implementation of blobmsg_check_array.
++ * It will limit all memory access performed on the blob to the
++ * range [attr, attr + len] (upper bound non inclusive) and is
++ * thus suited for checking of untrusted blob attributes.
++ */
++int blobmsg_check_array_len(const struct blob_attr *attr, int type, size_t len);
++
+ int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
+                   struct blob_attr **tb, void *data, unsigned int len);
+ int blobmsg_parse_array(const struct blobmsg_policy *policy, int policy_len,
+@@ -271,5 +318,11 @@ int blobmsg_printf(struct blob_buf *buf,
+ 	     rem >= sizeof(struct blob_attr) && (blob_pad_len(pos) <= rem) && \
+ 	     (blob_pad_len(pos) >= sizeof(struct blob_attr)); \
+ 	     rem -= blob_pad_len(pos), pos = blob_next(pos))
++
++#define __blobmsg_for_each_attr(pos, attr, rem) \
++	for (pos = (struct blob_attr *) (attr ? blobmsg_data(attr) : NULL); \
++	     rem >= sizeof(struct blob_attr) && (blob_pad_len(pos) <= rem) && \
++	     (blob_pad_len(pos) >= sizeof(struct blob_attr)); \
++	     rem -= blob_pad_len(pos), pos = blob_next(pos))
+ 
+ #endif