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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Kees Cook <keescook@chromium.org>
Cc: linux-hardening@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	Keith Packard <keithpac@amazon.com>,
	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: Re: [PATCH 19/64] ip: Use struct_group() for memcpy() regions
Date: Wed, 28 Jul 2021 07:55:53 +0200	[thread overview]
Message-ID: <YQDxaYrHu0PeBIuX@kroah.com> (raw)
In-Reply-To: <20210727205855.411487-20-keescook@chromium.org>

On Tue, Jul 27, 2021 at 01:58:10PM -0700, Kees Cook wrote:
> 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.
> 
> Use struct_group() in struct flowi4, struct ipv4hdr, and struct ipv6hdr
> around members saddr and daddr, so they can be referenced together. This
> will allow memcpy() and sizeof() to more easily reason about sizes,
> improve readability, and avoid future warnings about writing beyond the
> end of saddr.
> 
> "pahole" shows no size nor member offset changes to struct flowi4.
> "objdump -d" shows no meaningful object code changes (i.e. only source
> line number induced differences.)
> 
> Note that since this is a UAPI header, struct_group() has been open
> coded.
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  include/net/flow.h            |  6 ++++--
>  include/uapi/linux/if_ether.h | 12 ++++++++++--
>  include/uapi/linux/ip.h       | 12 ++++++++++--
>  include/uapi/linux/ipv6.h     | 12 ++++++++++--
>  net/core/flow_dissector.c     | 10 ++++++----
>  net/ipv4/ip_output.c          |  6 ++----
>  6 files changed, 42 insertions(+), 16 deletions(-)
> 
> diff --git a/include/net/flow.h b/include/net/flow.h
> index 6f5e70240071..f1a3b6c8eae2 100644
> --- a/include/net/flow.h
> +++ b/include/net/flow.h
> @@ -81,8 +81,10 @@ struct flowi4 {
>  #define flowi4_multipath_hash	__fl_common.flowic_multipath_hash
>  
>  	/* (saddr,daddr) must be grouped, same order as in IP header */
> -	__be32			saddr;
> -	__be32			daddr;
> +	struct_group(addrs,
> +		__be32			saddr;
> +		__be32			daddr;
> +	);
>  
>  	union flowi_uli		uli;
>  #define fl4_sport		uli.ports.sport
> diff --git a/include/uapi/linux/if_ether.h b/include/uapi/linux/if_ether.h
> index a0b637911d3c..8f5667b2ea92 100644
> --- a/include/uapi/linux/if_ether.h
> +++ b/include/uapi/linux/if_ether.h
> @@ -163,8 +163,16 @@
>  
>  #if __UAPI_DEF_ETHHDR
>  struct ethhdr {
> -	unsigned char	h_dest[ETH_ALEN];	/* destination eth addr	*/
> -	unsigned char	h_source[ETH_ALEN];	/* source ether addr	*/
> +	union {
> +		struct {
> +			unsigned char h_dest[ETH_ALEN];	  /* destination eth addr */
> +			unsigned char h_source[ETH_ALEN]; /* source ether addr	  */
> +		};
> +		struct {
> +			unsigned char h_dest[ETH_ALEN];	  /* destination eth addr */
> +			unsigned char h_source[ETH_ALEN]; /* source ether addr	  */
> +		} addrs;

A union of the same fields in the same structure in the same way?

Ah, because struct_group() can not be used here?  Still feels odd to see
in a userspace-visible header.

> +	};
>  	__be16		h_proto;		/* packet type ID field	*/
>  } __attribute__((packed));
>  #endif
> diff --git a/include/uapi/linux/ip.h b/include/uapi/linux/ip.h
> index e42d13b55cf3..33647a37e56b 100644
> --- a/include/uapi/linux/ip.h
> +++ b/include/uapi/linux/ip.h
> @@ -100,8 +100,16 @@ struct iphdr {
>  	__u8	ttl;
>  	__u8	protocol;
>  	__sum16	check;
> -	__be32	saddr;
> -	__be32	daddr;
> +	union {
> +		struct {
> +			__be32	saddr;
> +			__be32	daddr;
> +		} addrs;
> +		struct {
> +			__be32	saddr;
> +			__be32	daddr;
> +		};

Same here (except you named the first struct addrs, not the second,
unlike above).


> +	};
>  	/*The options start here. */
>  };
>  
> diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h
> index b243a53fa985..1c26d32e733b 100644
> --- a/include/uapi/linux/ipv6.h
> +++ b/include/uapi/linux/ipv6.h
> @@ -130,8 +130,16 @@ struct ipv6hdr {
>  	__u8			nexthdr;
>  	__u8			hop_limit;
>  
> -	struct	in6_addr	saddr;
> -	struct	in6_addr	daddr;
> +	union {
> +		struct {
> +			struct	in6_addr	saddr;
> +			struct	in6_addr	daddr;
> +		} addrs;
> +		struct {
> +			struct	in6_addr	saddr;
> +			struct	in6_addr	daddr;
> +		};

addrs first?  Consistancy is key :)

thanks,

greg k-h

  reply	other threads:[~2021-07-28  5:55 UTC|newest]

Thread overview: 158+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-27 20:57 [PATCH 00/64] Introduce strict memcpy() bounds checking Kees Cook
2021-07-27 20:57 ` [PATCH 01/64] media: omap3isp: Extract struct group for memcpy() region Kees Cook
2021-07-28  0:55   ` Gustavo A. R. Silva
2021-07-28  1:50     ` Kees Cook
2021-07-28  8:59   ` David Sterba
2021-07-28  9:14     ` Dan Carpenter
2021-07-28 21:37       ` Bart Van Assche
2021-07-28 21:37         ` David Sterba
2021-07-29  5:56           ` Greg Kroah-Hartman
2021-07-29  8:20             ` Dan Carpenter
2021-07-30  6:00               ` Kees Cook
2021-07-30  8:38                 ` David Sterba
2021-07-30  9:00                   ` Dan Carpenter
2021-07-30 16:44                     ` Kees Cook
2021-07-30 17:08                       ` Nick Desaulniers
2021-07-30 19:18                         ` Kees Cook
2021-07-27 20:57 ` [PATCH 02/64] mac80211: Use flex-array for radiotap header bitmap Kees Cook
2021-07-28  7:35   ` Dan Carpenter
2021-07-28  9:23     ` David Sterba
2021-07-28 21:54       ` Kees Cook
2021-07-29 10:45         ` David Sterba
2021-07-30  6:06           ` Kees Cook
2021-07-28 21:20     ` Kees Cook
2021-07-28 23:14     ` Kees Cook
2021-07-28 23:33     ` Kees Cook
2021-07-29  8:25       ` Dan Carpenter
2021-07-27 20:57 ` [PATCH 03/64] rpmsg: glink: Replace strncpy() with strscpy_pad() Kees Cook
2021-07-28  2:07   ` Gustavo A. R. Silva
2021-07-27 20:57 ` [PATCH 04/64] stddef: Introduce struct_group() helper macro Kees Cook
2021-07-28  2:32   ` Gustavo A. R. Silva
2021-07-28 10:54   ` Rasmus Villemoes
2021-07-28 21:59     ` Kees Cook
2021-07-30 22:19       ` Williams, Dan J
2021-07-31  2:59         ` Kees Cook
     [not found]           ` <CAKwiHFheDv2pwsm6Fa+-KnOFyvk7bfZQjb2BQ-CSwH61gxgVYg@mail.gmail.com>
2021-07-31 15:10             ` Kees Cook
2021-07-27 20:57 ` [PATCH 05/64] skbuff: Switch structure bounds to struct_group() Kees Cook
2021-07-28  3:50   ` Gustavo A. R. Silva
2021-07-27 20:57 ` [PATCH 06/64] bnxt_en: Use struct_group_attr() for memcpy() region Kees Cook
2021-07-28  1:03   ` Michael Chan
2021-07-28  4:45   ` Gustavo A. R. Silva
2021-07-27 20:57 ` [PATCH 07/64] staging: rtl8192e: Use struct_group() " Kees Cook
2021-07-27 22:30   ` Larry Finger
2021-07-28  5:45   ` Greg Kroah-Hartman
2021-07-27 20:57 ` [PATCH 08/64] staging: rtl8192u: " Kees Cook
2021-07-28  5:45   ` Greg Kroah-Hartman
2021-07-27 20:58 ` [PATCH 09/64] staging: rtl8723bs: Avoid field-overflowing memcpy() Kees Cook
2021-07-28  5:46   ` Greg Kroah-Hartman
2021-07-27 20:58 ` [PATCH 10/64] lib80211: Use struct_group() for memcpy() region Kees Cook
2021-07-28  5:52   ` Greg Kroah-Hartman
2021-08-13  8:04   ` Johannes Berg
2021-08-13 15:49     ` Kees Cook
2021-08-13 19:44       ` Johannes Berg
2021-07-27 20:58 ` [PATCH 11/64] net/mlx5e: Avoid field-overflowing memcpy() Kees Cook
2021-07-27 20:58 ` [PATCH 12/64] mwl8k: Use struct_group() for memcpy() region Kees Cook
2021-07-27 20:58 ` [PATCH 13/64] libertas: " Kees Cook
2021-07-27 20:58 ` [PATCH 14/64] libertas_tf: " Kees Cook
2021-07-27 20:58 ` [PATCH 15/64] ipw2x00: " Kees Cook
2021-07-28 18:55   ` Stanislav Yakovlev
2021-07-27 20:58 ` [PATCH 16/64] thermal: intel: int340x_thermal: " Kees Cook
2021-07-27 20:58 ` [PATCH 17/64] iommu/amd: " Kees Cook
2021-07-27 20:58 ` [PATCH 18/64] cxgb3: " Kees Cook
2021-07-27 20:58 ` [PATCH 19/64] ip: Use struct_group() for memcpy() regions Kees Cook
2021-07-28  5:55   ` Greg Kroah-Hartman [this message]
2021-07-28  6:14     ` Gustavo A. R. Silva
2021-07-28  6:19       ` Greg Kroah-Hartman
2021-07-28  6:31         ` Gustavo A. R. Silva
2021-07-28  6:37           ` Gustavo A. R. Silva
2021-07-28  6:41           ` Greg Kroah-Hartman
2021-07-28 21:01     ` Kees Cook
2021-07-29  1:59       ` Bart Van Assche
2021-07-27 20:58 ` [PATCH 20/64] intersil: Use struct_group() for memcpy() region Kees Cook
2021-07-27 20:58 ` [PATCH 21/64] cxgb4: " Kees Cook
2021-07-27 20:58 ` [PATCH 22/64] bnx2x: " Kees Cook
2021-07-27 20:58 ` [PATCH 23/64] drm/amd/pm: " Kees Cook
2021-07-30  2:07   ` Alex Deucher
2021-07-27 20:58 ` [PATCH 24/64] staging: wlan-ng: " Kees Cook
2021-07-28  5:45   ` Greg Kroah-Hartman
2021-07-27 20:58 ` [PATCH 25/64] drm/mga/mga_ioc32: " Kees Cook
2021-07-28  5:56   ` Greg Kroah-Hartman
2021-07-29 12:11     ` Daniel Vetter
2021-07-31  4:20       ` Kees Cook
2021-07-27 20:58 ` [PATCH 26/64] net/mlx5e: " Kees Cook
2021-07-27 20:58 ` [PATCH 27/64] HID: cp2112: " Kees Cook
2021-07-27 20:58 ` [PATCH 28/64] compiler_types.h: Remove __compiletime_object_size() Kees Cook
2021-07-27 20:58 ` [PATCH 29/64] lib/string: Move helper functions out of string.c Kees Cook
2021-07-27 20:58 ` [PATCH 30/64] fortify: Move remaining fortify helpers into fortify-string.h Kees Cook
2021-07-27 20:58 ` [PATCH 31/64] fortify: Explicitly disable Clang support Kees Cook
2021-07-27 21:18   ` Nathan Chancellor
2021-07-27 21:47     ` Kees Cook
2021-07-27 20:58 ` [PATCH 32/64] fortify: Add compile-time FORTIFY_SOURCE tests Kees Cook
2021-07-27 20:58 ` [PATCH 33/64] lib: Introduce CONFIG_TEST_MEMCPY Kees Cook
2021-07-27 23:31   ` Bart Van Assche
2021-07-27 23:33     ` Randy Dunlap
2021-07-28  1:30     ` Kees Cook
2021-07-27 20:58 ` [PATCH 34/64] fortify: Detect struct member overflows in memcpy() at compile-time Kees Cook
2021-07-27 22:43   ` Nick Desaulniers
2021-07-28  1:47     ` Kees Cook
2021-07-28 11:19   ` Rasmus Villemoes
2021-07-30  2:39     ` Kees Cook
2021-07-27 20:58 ` [PATCH 35/64] fortify: Detect struct member overflows in memmove() " Kees Cook
2021-07-27 20:58 ` [PATCH 36/64] scsi: ibmvscsi: Avoid multi-field memset() overflow by aiming at srp Kees Cook
2021-07-28  1:39   ` Martin K. Petersen
2021-07-28 18:57     ` Kees Cook
2021-07-29  3:35       ` Martin K. Petersen
2021-07-30 19:11         ` Tyrel Datwyler
2021-07-30 18:16     ` Tyrel Datwyler
2021-07-27 20:58 ` [PATCH 37/64] string.h: Introduce memset_after() for wiping trailing members/padding Kees Cook
2021-07-27 20:58 ` [PATCH 38/64] xfrm: Use memset_after() to clear padding Kees Cook
2021-07-27 20:58 ` [PATCH 39/64] mac80211: Use memset_after() to clear tx status Kees Cook
2021-07-31 15:55   ` Kees Cook
2021-08-13  7:40     ` Johannes Berg
2021-08-13 16:08       ` Kees Cook
2021-08-13 18:19         ` Johannes Berg
2021-08-13  7:41     ` Johannes Berg
2021-07-27 20:58 ` [PATCH 40/64] net: 802: Use memset_after() to clear struct fields Kees Cook
2021-07-27 20:58 ` [PATCH 41/64] net: dccp: Use memset_after() for TP zeroing Kees Cook
2021-07-27 20:58 ` [PATCH 42/64] net: qede: Use memset_after() for counters Kees Cook
2021-07-31 16:07   ` Kees Cook
2021-07-27 20:58 ` [PATCH 43/64] ath11k: Use memset_after() for clearing queue descriptors Kees Cook
2021-07-27 20:58 ` [PATCH 44/64] iw_cxgb4: Use memset_after() for cpl_t5_pass_accept_rpl Kees Cook
2021-07-27 20:58 ` [PATCH 45/64] intel_th: msu: Use memset_after() for clearing hw header Kees Cook
2021-07-27 20:58 ` [PATCH 46/64] IB/mthca: Use memset_after() for clearing mpt_entry Kees Cook
2021-07-27 20:58 ` [PATCH 47/64] btrfs: Use memset_after() to clear end of struct Kees Cook
2021-07-28  9:42   ` David Sterba
2021-07-28 21:56     ` Kees Cook
2021-07-29 10:33       ` David Sterba
2021-07-31 15:25         ` Kees Cook
2021-08-09 11:20           ` David Sterba
2021-07-27 20:58 ` [PATCH 48/64] drbd: Use struct_group() to zero algs Kees Cook
2021-07-28 21:45   ` Bart Van Assche
2021-07-30  2:31     ` Kees Cook
2021-07-30  2:57       ` Bart Van Assche
2021-07-30  9:25         ` Lars Ellenberg
2021-07-30 15:32       ` Nick Desaulniers
2021-07-27 20:58 ` [PATCH 49/64] cm4000_cs: Use struct_group() to zero struct cm4000_dev region Kees Cook
2021-07-28  5:48   ` Greg Kroah-Hartman
2021-07-27 20:58 ` [PATCH 50/64] KVM: x86: Use struct_group() to zero decode cache Kees Cook
2021-07-27 20:58 ` [PATCH 51/64] tracing: Use struct_group() to zero struct trace_iterator Kees Cook
2021-07-27 20:58 ` [PATCH 52/64] dm integrity: Use struct_group() to zero struct journal_sector Kees Cook
2021-07-27 20:58 ` [PATCH 53/64] HID: roccat: Use struct_group() to zero kone_mouse_event Kees Cook
2021-07-27 20:58 ` [PATCH 54/64] ipv6: Use struct_group() to zero rt6_info Kees Cook
2021-07-29 18:58   ` Jakub Kicinski
2021-07-31 15:01     ` Kees Cook
2021-07-27 20:58 ` [PATCH 55/64] RDMA/mlx5: Use struct_group() to zero struct mlx5_ib_mr Kees Cook
2021-07-27 20:58 ` [PATCH 56/64] ethtool: stats: Use struct_group() to clear all stats at once Kees Cook
2021-07-27 20:58 ` [PATCH 57/64] netfilter: conntrack: Use struct_group() to zero struct nf_conn Kees Cook
2021-07-27 20:58 ` [PATCH 58/64] powerpc: Split memset() to avoid multi-field overflow Kees Cook
2021-08-05 11:36   ` Michael Ellerman
2021-07-27 20:58 ` [PATCH 59/64] fortify: Detect struct member overflows in memset() at compile-time Kees Cook
2021-07-27 20:58 ` [PATCH 60/64] fortify: Work around Clang inlining bugs Kees Cook
2021-07-27 20:58 ` [PATCH 61/64] Makefile: Enable -Warray-bounds Kees Cook
2021-07-27 20:58 ` [PATCH 62/64] netlink: Avoid false-positive memcpy() warning Kees Cook
2021-07-28  5:49   ` Greg Kroah-Hartman
2021-07-28 11:24     ` Rasmus Villemoes
2021-07-30  1:39       ` Kees Cook
2021-07-30  1:41     ` Kees Cook
2021-07-27 20:58 ` [PATCH 63/64] iwlwifi: dbg_ini: Split memcpy() to avoid multi-field write Kees Cook
2021-07-27 20:58 ` [PATCH 64/64] fortify: Add run-time WARN for cross-field memcpy() Kees Cook

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