[05/64] skbuff: Switch structure bounds to struct_group()

Message ID	20210727205855.411487-6-keescook@chromium.org
State	Superseded
Headers	show Return-Path: <linux-wireless-owner@kernel.org> From: Kees Cook <keescook@chromium.org> To: linux-hardening@vger.kernel.org Cc: Kees Cook <keescook@chromium.org>, "Gustavo A. R. Silva" <gustavoars@kernel.org>, Keith Packard <keithpac@amazon.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev, linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com Subject: [PATCH 05/64] skbuff: Switch structure bounds to struct_group() Date: Tue, 27 Jul 2021 13:57:56 -0700 Message-Id: <20210727205855.411487-6-keescook@chromium.org> In-Reply-To: <20210727205855.411487-1-keescook@chromium.org> References: <20210727205855.411487-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	Introduce strict memcpy() bounds checking \| expand [00/64] Introduce strict memcpy() bounds checking [01/64] media: omap3isp: Extract struct group for memcpy() region [02/64] mac80211: Use flex-array for radiotap header bitmap [03/64] rpmsg: glink: Replace strncpy() with strscpy_pad() [04/64] stddef: Introduce struct_group() helper macro [05/64] skbuff: Switch structure bounds to struct_group() [06/64] bnxt_en: Use struct_group_attr() for memcpy() region [07/64] staging: rtl8192e: Use struct_group() for memcpy() region [08/64] staging: rtl8192u: Use struct_group() for memcpy() region [09/64] staging: rtl8723bs: Avoid field-overflowing memcpy() [10/64] lib80211: Use struct_group() for memcpy() region [11/64] net/mlx5e: Avoid field-overflowing memcpy() [12/64] mwl8k: Use struct_group() for memcpy() region [13/64] libertas: Use struct_group() for memcpy() region [14/64] libertas_tf: Use struct_group() for memcpy() region [15/64] ipw2x00: Use struct_group() for memcpy() region [16/64] thermal: intel: int340x_thermal: Use struct_group() for memcpy() region [17/64] iommu/amd: Use struct_group() for memcpy() region [18/64] cxgb3: Use struct_group() for memcpy() region [19/64] ip: Use struct_group() for memcpy() regions [20/64] intersil: Use struct_group() for memcpy() region [21/64] cxgb4: Use struct_group() for memcpy() region [22/64] bnx2x: Use struct_group() for memcpy() region [23/64] drm/amd/pm: Use struct_group() for memcpy() region [24/64] staging: wlan-ng: Use struct_group() for memcpy() region [25/64] drm/mga/mga_ioc32: Use struct_group() for memcpy() region [26/64] net/mlx5e: Use struct_group() for memcpy() region [27/64] HID: cp2112: Use struct_group() for memcpy() region [28/64] compiler_types.h: Remove __compiletime_object_size() [29/64] lib/string: Move helper functions out of string.c [30/64] fortify: Move remaining fortify helpers into fortify-string.h [31/64] fortify: Explicitly disable Clang support [32/64] fortify: Add compile-time FORTIFY_SOURCE tests [33/64] lib: Introduce CONFIG_TEST_MEMCPY [34/64] fortify: Detect struct member overflows in memcpy() at compile-time [35/64] fortify: Detect struct member overflows in memmove() at compile-time [36/64] scsi: ibmvscsi: Avoid multi-field memset() overflow by aiming at srp [37/64] string.h: Introduce memset_after() for wiping trailing members/padding [38/64] xfrm: Use memset_after() to clear padding [39/64] mac80211: Use memset_after() to clear tx status [40/64] net: 802: Use memset_after() to clear struct fields [41/64] net: dccp: Use memset_after() for TP zeroing [42/64] net: qede: Use memset_after() for counters [43/64] ath11k: Use memset_after() for clearing queue descriptors [44/64] iw_cxgb4: Use memset_after() for cpl_t5_pass_accept_rpl [45/64] intel_th: msu: Use memset_after() for clearing hw header [46/64] IB/mthca: Use memset_after() for clearing mpt_entry [47/64] btrfs: Use memset_after() to clear end of struct [48/64] drbd: Use struct_group() to zero algs [49/64] cm4000_cs: Use struct_group() to zero struct cm4000_dev region [50/64] KVM: x86: Use struct_group() to zero decode cache [51/64] tracing: Use struct_group() to zero struct trace_iterator [52/64] dm integrity: Use struct_group() to zero struct journal_sector [53/64] HID: roccat: Use struct_group() to zero kone_mouse_event [54/64] ipv6: Use struct_group() to zero rt6_info [55/64] RDMA/mlx5: Use struct_group() to zero struct mlx5_ib_mr [56/64] ethtool: stats: Use struct_group() to clear all stats at once [57/64] netfilter: conntrack: Use struct_group() to zero struct nf_conn [58/64] powerpc: Split memset() to avoid multi-field overflow [59/64] fortify: Detect struct member overflows in memset() at compile-time [60/64] fortify: Work around Clang inlining bugs [61/64] Makefile: Enable -Warray-bounds [62/64] netlink: Avoid false-positive memcpy() warning [63/64] iwlwifi: dbg_ini: Split memcpy() to avoid multi-field write [64/64] fortify: Add run-time WARN for cross-field memcpy()

Message ID

20210727205855.411487-6-keescook@chromium.org

State

Superseded

Headers

From: Kees Cook <keescook@chromium.org>
To: linux-hardening@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	Keith Packard <keithpac@amazon.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
	netdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-staging@lists.linux.dev, linux-block@vger.kernel.org,
	linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: [PATCH 05/64] skbuff: Switch structure bounds to struct_group()
Date: Tue, 27 Jul 2021 13:57:56 -0700
Message-Id: <20210727205855.411487-6-keescook@chromium.org>
In-Reply-To: <20210727205855.411487-1-keescook@chromium.org>
References: <20210727205855.411487-1-keescook@chromium.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Series

Introduce strict memcpy() bounds checking | expand

Commit Message

Kees Cook July 27, 2021, 8:57 p.m. UTC

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally writing across neighboring fields.

Replace the existing empty member position markers "headers_start" and
"headers_end" with a struct_group(). This will allow memcpy() and sizeof()
to more easily reason about sizes, and improve readability.

"pahole" shows no size nor member offset changes to struct sk_buff.
"objdump -d" shows no no meaningful object code changes (i.e. only source
line number induced differences and optimizations.)

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/net/wireguard/queueing.h |  4 +---
 include/linux/skbuff.h           |  9 ++++-----
 net/core/skbuff.c                | 14 +++++---------
 3 files changed, 10 insertions(+), 17 deletions(-)

diff --git a/drivers/net/wireguard/queueing.h b/drivers/net/wireguard/queueing.h
index 4ef2944a68bc..52da5e963003 100644
--- a/drivers/net/wireguard/queueing.h
+++ b/drivers/net/wireguard/queueing.h
@@ -79,9 +79,7 @@  static inline void wg_reset_packet(struct sk_buff *skb, bool encapsulating)
 	u8 sw_hash = skb->sw_hash;
 	u32 hash = skb->hash;
 	skb_scrub_packet(skb, true);
-	memset(&skb->headers_start, 0,
-	       offsetof(struct sk_buff, headers_end) -
-		       offsetof(struct sk_buff, headers_start));
+	memset(&skb->headers, 0, sizeof(skb->headers));
 	if (encapsulating) {
 		skb->l4_hash = l4_hash;
 		skb->sw_hash = sw_hash;
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index f19190820e63..b4032e9b130e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -800,11 +800,10 @@  struct sk_buff {
 	__u8			active_extensions;
 #endif
 
-	/* fields enclosed in headers_start/headers_end are copied
+	/* Fields enclosed in headers group are copied
 	 * using a single memcpy() in __copy_skb_header()
 	 */
-	/* private: */
-	__u32			headers_start[0];
+	struct_group(headers,
 	/* public: */
 
 /* if you move pkt_type around you also must adapt those constants */
@@ -920,8 +919,8 @@  struct sk_buff {
 	u64			kcov_handle;
 #endif
 
-	/* private: */
-	__u32			headers_end[0];
+	); /* end headers group */
+
 	/* public: */
 
 	/* These elements must be at the end, see alloc_skb() for details.  */
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index fc7942c0dddc..5f29c65507e0 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -987,12 +987,10 @@  void napi_consume_skb(struct sk_buff *skb, int budget)
 }
 EXPORT_SYMBOL(napi_consume_skb);
 
-/* Make sure a field is enclosed inside headers_start/headers_end section */
+/* Make sure a field is contained by headers group */
 #define CHECK_SKB_FIELD(field) \
-	BUILD_BUG_ON(offsetof(struct sk_buff, field) <		\
-		     offsetof(struct sk_buff, headers_start));	\
-	BUILD_BUG_ON(offsetof(struct sk_buff, field) >		\
-		     offsetof(struct sk_buff, headers_end));	\
+	BUILD_BUG_ON(offsetof(struct sk_buff, field) !=		\
+		     offsetof(struct sk_buff, headers.field));	\
 
 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 {
@@ -1004,14 +1002,12 @@  static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 	__skb_ext_copy(new, old);
 	__nf_copy(new, old, false);
 
-	/* Note : this field could be in headers_start/headers_end section
+	/* Note : this field could be in the headers group.
 	 * It is not yet because we do not want to have a 16 bit hole
 	 */
 	new->queue_mapping = old->queue_mapping;
 
-	memcpy(&new->headers_start, &old->headers_start,
-	       offsetof(struct sk_buff, headers_end) -
-	       offsetof(struct sk_buff, headers_start));
+	memcpy(&new->headers, &old->headers, sizeof(new->headers));
 	CHECK_SKB_FIELD(protocol);
 	CHECK_SKB_FIELD(csum);
 	CHECK_SKB_FIELD(hash);

[05/64] skbuff: Switch structure bounds to struct_group()

Commit Message

Patch