From mboxrd@z Thu Jan 1 00:00:00 1970 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 5E709BA3E for ; Tue, 7 Mar 2023 17:49:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BED63C433D2; Tue, 7 Mar 2023 17:49:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678211392; bh=ix4XA8LgIeBUpIBPMcFU6UVI/cKS8WZK4a9MKCdJvEU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nLTsgkCrJqgEZ3bSdQCWJfpuSmUFHbHYhP3cLhTh/fiUl518C5KFq8R3B3S57ehzO 0Pcp5qBi3kgOZmm23eJbQzryyAgILPpWIoxjvlON/HUgZ0POcwhu+0EIMcpAv5t0k1 hdY5XzMBberHe2iwNvVQRou8MFV/AS1mFpvpAI5U= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Larry Dewey , Tom Lendacky , "Borislav Petkov (AMD)" , stable@kernel.org Subject: [PATCH 6.2 0847/1001] virt/sev-guest: Return -EIO if certificate buffer is not large enough Date: Tue, 7 Mar 2023 18:00:19 +0100 Message-Id: <20230307170058.569605003@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307170022.094103862@linuxfoundation.org> References: <20230307170022.094103862@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Tom Lendacky commit dd093fb08e8f8a958fec4eef36f9f09eac047f60 upstream. Commit 47894e0fa6a5 ("virt/sev-guest: Prevent IV reuse in the SNP guest driver") changed the behavior associated with the return value when the caller does not supply a large enough certificate buffer. Prior to the commit a value of -EIO was returned. Now, 0 is returned. This breaks the established ABI with the user. Change the code to detect the buffer size error and return -EIO. Fixes: 47894e0fa6a5 ("virt/sev-guest: Prevent IV reuse in the SNP guest driver") Reported-by: Larry Dewey Signed-off-by: Tom Lendacky Signed-off-by: Borislav Petkov (AMD) Tested-by: Larry Dewey Cc: Link: https://lore.kernel.org/r/2afbcae6daf13f7ad5a4296692e0a0fe1bc1e4ee.1677083979.git.thomas.lendacky@amd.com Signed-off-by: Greg Kroah-Hartman --- drivers/virt/coco/sev-guest/sev-guest.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -377,9 +377,26 @@ static int handle_guest_request(struct s snp_dev->input.data_npages = certs_npages; } + /* + * Increment the message sequence number. There is no harm in doing + * this now because decryption uses the value stored in the response + * structure and any failure will wipe the VMPCK, preventing further + * use anyway. + */ + snp_inc_msg_seqno(snp_dev); + if (fw_err) *fw_err = err; + /* + * If an extended guest request was issued and the supplied certificate + * buffer was not large enough, a standard guest request was issued to + * prevent IV reuse. If the standard request was successful, return -EIO + * back to the caller as would have originally been returned. + */ + if (!rc && err == SNP_GUEST_REQ_INVALID_LEN) + return -EIO; + if (rc) { dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", @@ -395,9 +412,6 @@ static int handle_guest_request(struct s goto disable_vmpck; } - /* Increment to new message sequence after payload decryption was successful. */ - snp_inc_msg_seqno(snp_dev); - return 0; disable_vmpck: