121 lines
5.0 KiB
Diff
121 lines
5.0 KiB
Diff
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From 555d93f2daa551dc2311b15210a918aa79ed18ff Mon Sep 17 00:00:00 2001
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From: Laszlo Ersek <lersek@redhat.com>
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Date: Tue, 14 Jan 2020 12:39:06 +0100
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Subject: [PATCH 2/2] NetworkPkg/HttpDxe: fix 32-bit truncation in HTTPS
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download
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Laszlo Ersek <lersek@redhat.com>
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Message-id: <20200114123906.8547-3-lersek@redhat.com>
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Patchwork-id: 93340
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O-Subject: [RHEL-8.2.0 edk2 PATCH 2/2] NetworkPkg/HttpDxe: fix 32-bit truncation in HTTPS download
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Bugzilla: 1789797
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RH-Acked-by: Vitaly Kuznetsov <vkuznets@redhat.com>
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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When downloading over TLS, each TLS message ("APP packet") is returned as
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a (decrypted) fragment table by EFI_TLS_PROTOCOL.ProcessPacket().
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The TlsProcessMessage() function in "NetworkPkg/HttpDxe/HttpsSupport.c"
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linearizes the fragment table into a single contiguous data block. The
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resultant flat data block contains both TLS headers and data.
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The HttpsReceive() function parses the actual application data -- in this
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case: decrypted HTTP data -- out of the flattened TLS data block, peeling
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off the TLS headers.
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The HttpResponseWorker() function in "NetworkPkg/HttpDxe/HttpImpl.c"
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propagates this HTTP data outwards, implementing the
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EFI_HTTP_PROTOCOL.Response() function.
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Now consider the following documentation for EFI_HTTP_PROTOCOL.Response(),
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quoted from "MdePkg/Include/Protocol/Http.h":
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> It is the responsibility of the caller to allocate a buffer for Body and
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> specify the size in BodyLength. If the remote host provides a response
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> that contains a content body, up to BodyLength bytes will be copied from
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> the receive buffer into Body and BodyLength will be updated with the
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> amount of bytes received and copied to Body. This allows the client to
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> download a large file in chunks instead of into one contiguous block of
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> memory.
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Note that, if the caller-allocated buffer is larger than the
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server-provided chunk, then the transfer length is limited by the latter.
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This is in fact the dominant case when downloading a huge file (for which
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UefiBootManagerLib allocated a huge contiguous RAM Disk buffer) in small
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TLS messages.
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For adjusting BodyLength as described above -- i.e., to the application
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data chunk that has been extracted from the TLS message --, the
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HttpResponseWorker() function employs the following assignment:
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HttpMsg->BodyLength = MIN (Fragment.Len, (UINT32) HttpMsg->BodyLength);
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The (UINT32) cast is motivated by the MIN() requirement -- in
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"MdePkg/Include/Base.h" -- that both arguments be of the same type.
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"Fragment.Len" (NET_FRAGMENT.Len) has type UINT32, and
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"HttpMsg->BodyLength" (EFI_HTTP_MESSAGE.BodyLength) has type UINTN.
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Therefore a cast is indeed necessary.
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Unfortunately, the cast is done in the wrong direction. Consider the
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following circumstances:
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- "Fragment.Len" happens to be consistently 16KiB, dictated by the HTTPS
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Server's TLS stack,
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- the size of the file to download is 4GiB + N*16KiB, where N is a
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positive integer.
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As the download progresses, each received 16KiB application data chunk
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brings the *next* input value of BodyLength closer down to 4GiB. The cast
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in MIN() always masks off the high-order bits from the input value of
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BodyLength, but this is no problem because the low-order bits are nonzero,
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therefore the MIN() always permits progress.
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However, once BodyLength reaches 4GiB exactly on input, the MIN()
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invocation produces a zero value. HttpResponseWorker() adjusts the output
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value of BodyLength to zero, and then passes it to HttpParseMessageBody().
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HttpParseMessageBody() (in "NetworkPkg/Library/DxeHttpLib/DxeHttpLib.c")
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rejects the zero BodyLength with EFI_INVALID_PARAMETER, which is fully
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propagated outwards, and aborts the HTTPS download. HttpBootDxe writes the
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message "Error: Unexpected network error" to the UEFI console.
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For example, a file with size (4GiB + 197MiB) terminates after downloading
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just 197MiB.
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Invert the direction of the cast: widen "Fragment.Len" to UINTN.
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Cc: Jiaxin Wu <jiaxin.wu@intel.com>
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Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com>
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Cc: Siyuan Fu <siyuan.fu@intel.com>
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Signed-off-by: Laszlo Ersek <lersek@redhat.com>
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Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
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Reviewed-by: Siyuan Fu <siyuan.fu@intel.com>
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Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com>
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(cherry picked from commit 4cca7923992a13f6b753782f469ee944da2db796)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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NetworkPkg/HttpDxe/HttpImpl.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/NetworkPkg/HttpDxe/HttpImpl.c b/NetworkPkg/HttpDxe/HttpImpl.c
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index 6b87731..1acbb60 100644
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--- a/NetworkPkg/HttpDxe/HttpImpl.c
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+++ b/NetworkPkg/HttpDxe/HttpImpl.c
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@@ -1348,7 +1348,7 @@ HttpResponseWorker (
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//
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// Process the received the body packet.
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//
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- HttpMsg->BodyLength = MIN (Fragment.Len, (UINT32) HttpMsg->BodyLength);
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+ HttpMsg->BodyLength = MIN ((UINTN) Fragment.Len, HttpMsg->BodyLength);
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CopyMem (HttpMsg->Body, Fragment.Bulk, HttpMsg->BodyLength);
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--
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1.8.3.1
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