From patchwork Wed Oct 16 00:27:16 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 836142 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7EE7221E3BE; Wed, 16 Oct 2024 00:27:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729038440; cv=none; b=AXda3WNdYv5PDeGcAk64HZ3nlc6FMTyIesACNHAmURYvf14bDdUO3C10K9OejfOMXXqJRgZ3zpN/4FC8nm5gNv7Xz8VN89H3es/Jt1BWoumRGJN7C5SfFA8U/DwXaPlgZCzer4tlSQpneBqAyUz0gj2DeBgik7o9fPEvTpYmdL8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729038440; c=relaxed/simple; bh=tb27nyjCDeyfMIeUU/H/vPrhrpUAIwTNDYMgKdWPE/k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=n6BveyD+Bqv1iNj+myTSlS7qRkMy9QTwqeUp0pxgL5XPxNNSy6caB/371irePsBePQ9gpnEC9lrWo/Wofd93IPL9jmLPkuP7B3364vxRZNuIUfHYwfTwJhft7qztFhWr2mDMTmpSgIi0IXy7dCaOE9WR/Ag31VgFWeFlNBc7ysw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EVnUjrir; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EVnUjrir" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A437CC4CEC6; Wed, 16 Oct 2024 00:27:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729038440; bh=tb27nyjCDeyfMIeUU/H/vPrhrpUAIwTNDYMgKdWPE/k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EVnUjrirJfI0CQ6PbgD9SsPhu0EYkLRiy6T4LvhzCGWDRwlT6ZNBIiDhA15ejC1GS CaqTLPLzonrxQV+iQPTJETIShHv6gKfo6dHHoz/CFDkAuHriwUkm3PFQCjQBYw6zKm 8oP7yjcUVwyTRarcEYaMLCt70EJmi+kMvaQzAFXjhdSOLLggBWSQgkj/ga1wDuRLc0 3gvd8h6ZNn/vQhwwuow4w1prgNmxpfIPUT+/zlPMPkXf9GQuZ12B9MoLBHjzt1l+qf h769qvKrVGqmZCMDzsgVf9Q7TQu8R5kNNDUptV1KTs7eeiBfGVAUEYRlri4rDGnL1H EEt2NmRME0thQ== Date: Tue, 15 Oct 2024 18:27:16 -0600 From: "Gustavo A. R. Silva" To: Andrew Lunn , Johannes Berg , David Ahern , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org, linux-wireless@vger.kernel.org, Kees Cook Subject: [PATCH 1/5][next] net: dev: Introduce struct sockaddr_legacy Message-ID: <1c12601bea3e9c18da6adc106bfcf5b7569e5dfb.1729037131.git.gustavoars@kernel.org> References: Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: We are currently working on enabling the -Wflex-array-member-not-at-end compiler option. This option has helped us detect several objects of the type `struct sockaddr` that appear in the middle of composite structures like `struct rtentry`, `struct compat_rtentry`, and others: include/uapi/linux/wireless.h:751:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/wireless.h:776:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/wireless.h:833:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/wireless.h:857:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/wireless.h:864:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/route.h:33:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/route.h:34:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/route.h:35:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/if_arp.h:118:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/if_arp.h:119:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/if_arp.h:121:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/if_arp.h:126:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/uapi/linux/if_arp.h:127:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/net/compat.h:34:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] include/net/compat.h:35:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] fs/nfsd/nfsd.h:74:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] fs/nfsd/nfsd.h:75:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] In order to fix the warnings above, we introduce `struct sockaddr_legacy`. The intention is to use it to replace the type of several struct members in the middle of composite structures, currently of type `struct sockaddr`. These middle struct members are currently causing thousands of warnings because `struct sockaddr` contains a flexible-array member, introduced by commit b5f0de6df6dce ("net: dev: Convert sa_data to flexible array in struct sockaddr"). The new `struct sockaddr_legacy` doesn't include a flexible-array member, making it suitable for use as the type of middle members in composite structs that don't really require the flexible-array member in `struct sockaddr`, thus avoiding -Wflex-array-member-not-at-end warnings. Signed-off-by: Gustavo A. R. Silva Reviewed-by: Kuniyuki Iwashima --- include/linux/socket.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/include/linux/socket.h b/include/linux/socket.h index d18cc47e89bd..f370ae0e6c82 100644 --- a/include/linux/socket.h +++ b/include/linux/socket.h @@ -40,6 +40,25 @@ struct sockaddr { }; }; +/* + * This is the legacy form of `struct sockaddr`. The original `struct sockaddr` + * was modified in commit b5f0de6df6dce ("net: dev: Convert sa_data to flexible + * array in struct sockaddR") due to the fact that "One of the worst offenders + * of "fake flexible arrays" is struct sockaddr". This means that the original + * `char sa_data[14]` behaved as a flexible array at runtime, so a proper + * flexible-array member was introduced. + * + * This caused several flexible-array-in-the-middle issues: + * https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wflex-array-member-not-at-end + * + * `struct sockaddr_legacy` replaces `struct sockaddr` in all instances where + * objects of this type do not appear at the end of composite structures. + */ +struct sockaddr_legacy { + sa_family_t sa_family; /* address family, AF_xxx */ + char sa_data[14]; /* 14 bytes of protocol address */ +}; + struct linger { int l_onoff; /* Linger active */ int l_linger; /* How long to linger for */