From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 In-Reply-To: <19a7add8-adaf-4ad4-6ae3-4a62967656b9@redhat.com> References: <1515636190-24061-1-git-send-email-keescook@chromium.org> <1515636190-24061-28-git-send-email-keescook@chromium.org> <19a7add8-adaf-4ad4-6ae3-4a62967656b9@redhat.com> From: Kees Cook Date: Thu, 18 Jan 2018 13:36:03 -0800 Message-ID: Subject: Re: [PATCH 27/38] sctp: Copy struct sctp_sock.autoclose to userspace using put_user() To: Laura Abbott Cc: LKML , David Windsor , Vlad Yasevich , Neil Horman , "David S. Miller" , linux-sctp@vger.kernel.org, Network Development , Linus Torvalds , Alexander Viro , Andrew Morton , Andy Lutomirski , Christoph Hellwig , Christoph Lameter , Mark Rutland , "Martin K. Petersen" , Paolo Bonzini , Christian Borntraeger , Christoffer Dall , Dave Kleikamp , Jan Kara , Luis de Bethencourt , Marc Zyngier , Rik van Riel , Matthew Garrett , "linux-fsdevel@vger.kernel.org" , linux-arch , Linux-MM , kernel-hardening@lists.openwall.com Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: On Thu, Jan 18, 2018 at 1:31 PM, Laura Abbott wrote: > On 01/10/2018 06:02 PM, Kees Cook wrote: >> >> From: David Windsor >> >> The autoclose field can be copied with put_user(), so there is no need to >> use copy_to_user(). In both cases, hardened usercopy is being bypassed >> since the size is constant, and not open to runtime manipulation. >> >> This patch is verbatim from Brad Spengler/PaX Team's PAX_USERCOPY >> whitelisting code in the last public patch of grsecurity/PaX based on my >> understanding of the code. Changes or omissions from the original code are >> mine and don't reflect the original grsecurity/PaX code. >> > > Just tried a quick rebase and it looks like this conflicts with > c76f97c99ae6 ("sctp: make use of pre-calculated len") > I don't think we can use put_user if we're copying via the full > len? It should be fine, since: len = sizeof(int); c76f97c99ae6 just does a swap of sizeof(int) with len, put_user() will work in either case, since autoclose will always be int sized. -Kees > > Thanks, > Laura > > >> Signed-off-by: David Windsor >> [kees: adjust commit log] >> Cc: Vlad Yasevich >> Cc: Neil Horman >> Cc: "David S. Miller" >> Cc: linux-sctp@vger.kernel.org >> Cc: netdev@vger.kernel.org >> Signed-off-by: Kees Cook >> --- >> net/sctp/socket.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/net/sctp/socket.c b/net/sctp/socket.c >> index efbc8f52c531..15491491ec88 100644 >> --- a/net/sctp/socket.c >> +++ b/net/sctp/socket.c >> @@ -5011,7 +5011,7 @@ static int sctp_getsockopt_autoclose(struct sock >> *sk, int len, char __user *optv >> len = sizeof(int); >> if (put_user(len, optlen)) >> return -EFAULT; >> - if (copy_to_user(optval, &sctp_sk(sk)->autoclose, sizeof(int))) >> + if (put_user(sctp_sk(sk)->autoclose, (int __user *)optval)) >> return -EFAULT; >> return 0; >> } >> > -- Kees Cook Pixel Security -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org