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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id u21sm2725385pfh.163.2021.08.13.08.49.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Aug 2021 08:49:08 -0700 (PDT) Date: Fri, 13 Aug 2021 08:49:07 -0700 From: Kees Cook To: Johannes Berg Cc: linux-hardening@vger.kernel.org, "Gustavo A. R. Silva" , Keith Packard , Greg Kroah-Hartman , Andrew Morton , 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 10/64] lib80211: Use struct_group() for memcpy() region Message-ID: <202108130846.EC339BCA@keescook> References: <20210727205855.411487-1-keescook@chromium.org> <20210727205855.411487-11-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Fri, Aug 13, 2021 at 10:04:09AM +0200, Johannes Berg wrote: > On Tue, 2021-07-27 at 13:58 -0700, Kees Cook wrote: > > > > +++ b/include/linux/ieee80211.h > > @@ -297,9 +297,11 @@ static inline u16 ieee80211_sn_sub(u16 sn1, u16 sn2) > >  struct ieee80211_hdr { > >   __le16 frame_control; > >   __le16 duration_id; > > - u8 addr1[ETH_ALEN]; > > - u8 addr2[ETH_ALEN]; > > - u8 addr3[ETH_ALEN]; > > + struct_group(addrs, > > + u8 addr1[ETH_ALEN]; > > + u8 addr2[ETH_ALEN]; > > + u8 addr3[ETH_ALEN]; > > + ); > >   __le16 seq_ctrl; > >   u8 addr4[ETH_ALEN]; > >  } __packed __aligned(2); > > This file isn't really just lib80211, it's also used by everyone else > for 802.11, but I guess that's OK - after all, this doesn't really > result in any changes here. > > > +++ b/net/wireless/lib80211_crypt_ccmp.c > > @@ -136,7 +136,8 @@ static int ccmp_init_iv_and_aad(const struct ieee80211_hdr *hdr, > >   pos = (u8 *) hdr; > >   aad[0] = pos[0] & 0x8f; > >   aad[1] = pos[1] & 0xc7; > > - memcpy(aad + 2, hdr->addr1, 3 * ETH_ALEN); > > + BUILD_BUG_ON(sizeof(hdr->addrs) != 3 * ETH_ALEN); > > + memcpy(aad + 2, &hdr->addrs, ETH_ALEN); > > > However, how is it you don't need the same change in net/mac80211/wpa.c? > > We have three similar instances: > > /* AAD (extra authenticate-only data) / masked 802.11 header > * FC | A1 | A2 | A3 | SC | [A4] | [QC] */ > put_unaligned_be16(len_a, &aad[0]); > put_unaligned(mask_fc, (__le16 *)&aad[2]); > memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN); > > > and > > memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN); > > and > > memcpy(aad + 2, &hdr->addr1, 3 * ETH_ALEN); > > so those should also be changed, it seems? Ah! Yes, thanks for pointing this out. During earlier development I split the "cross-field write" changes from the "cross-field read" changes, and it looks like I missed moving lib80211_crypt_ccmp.c into that portion of the series (which I haven't posted nor finished -- it's lower priority than fixing the cross-field writes). > In which case I'd probably prefer to do this separately from the staging > drivers ... Agreed. Sorry for the noise on that part. I will double-check the other patches. -- Kees Cook