From: Borislav Petkov <bp@alien8.de>
To: Joerg Roedel <joro@8bytes.org>
Cc: x86@kernel.org, Joerg Roedel <jroedel@suse.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Kees Cook <keescook@chromium.org>,
Arvind Sankar <nivedita@alum.mit.edu>,
Martin Radev <martin.b.radev@gmail.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 3/5] x86/boot/compressed/64: Check SEV encryption in 64-bit boot-path
Date: Tue, 27 Oct 2020 12:09:45 +0100 [thread overview]
Message-ID: <20201027110945.GD15580@zn.tnic> (raw)
In-Reply-To: <20201021123938.3696-4-joro@8bytes.org>
On Wed, Oct 21, 2020 at 02:39:36PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
>
> Check whether the hypervisor reported the correct C-bit when running as
> an SEV guest. Using a wrong C-bit position could be used to leak
> sensitive data from the guest to the hypervisor.
>
> The check function is in arch/x86/kernel/sev_verify_cbit.S so that it
> can be re-used in the running kernel image.
>
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
> arch/x86/boot/compressed/ident_map_64.c | 1 +
> arch/x86/boot/compressed/mem_encrypt.S | 4 ++
> arch/x86/boot/compressed/misc.h | 2 +
> arch/x86/kernel/sev_verify_cbit.S | 90 +++++++++++++++++++++++++
> 4 files changed, 97 insertions(+)
> create mode 100644 arch/x86/kernel/sev_verify_cbit.S
>
> diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
> index 063a60edcf99..73abba3312a7 100644
> --- a/arch/x86/boot/compressed/ident_map_64.c
> +++ b/arch/x86/boot/compressed/ident_map_64.c
> @@ -153,6 +153,7 @@ void initialize_identity_maps(void)
> * into cr3.
> */
> add_identity_map((unsigned long)_head, (unsigned long)_end);
> + sev_verify_cbit(top_level_pgt);
> write_cr3(top_level_pgt);
> }
Btw, might wanna redo them ontop of -rc1 because this looks like this after
Arvind's three fixes:
diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
index a5e5db6ada3c..81f6003553f8 100644
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -162,6 +162,7 @@ void initialize_identity_maps(void *rmode)
add_identity_map((unsigned long)boot_params, (unsigned long)(boot_params + 1));
cmdline = get_cmd_line_ptr();
add_identity_map(cmdline, cmdline + COMMAND_LINE_SIZE);
+ sev_verify_cbit(top_level_pgt);
/* Load the new page-table. */
write_cr3(top_level_pgt);
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-10-27 11:09 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-21 12:39 [PATCH v3 0/5] x86/sev-es: Mitigate some HV attack vectors Joerg Roedel
2020-10-21 12:39 ` [PATCH v3 1/5] x86/boot/compressed/64: Introduce sev_status Joerg Roedel
2020-10-26 18:27 ` Borislav Petkov
2020-10-28 8:23 ` Joerg Roedel
2020-10-28 16:50 ` Arvind Sankar
2020-10-28 16:55 ` Joerg Roedel
2020-10-21 12:39 ` [PATCH v3 2/5] x86/boot/compressed/64: Add CPUID sanity check to early #VC handler Joerg Roedel
2020-10-27 10:38 ` Borislav Petkov
2020-10-28 8:31 ` Joerg Roedel
2020-10-21 12:39 ` [PATCH v3 3/5] x86/boot/compressed/64: Check SEV encryption in 64-bit boot-path Joerg Roedel
2020-10-27 11:08 ` Borislav Petkov
2020-10-28 8:38 ` Joerg Roedel
2020-10-27 11:09 ` Borislav Petkov [this message]
2020-10-21 12:39 ` [PATCH v3 4/5] x86/head/64: Check SEV encryption before switching to kernel page-table Joerg Roedel
2020-10-27 11:20 ` Borislav Petkov
2020-10-21 12:39 ` [PATCH v3 5/5] x86/sev-es: Do not support MMIO to/from encrypted memory Joerg Roedel
2020-10-27 11:26 ` Borislav Petkov
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