From: Peter Zijlstra <peterz@infradead.org>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org,
hch@infradead.org, sean.j.christopherson@intel.com,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org,
kenny@panix.com, jeyu@kernel.org, rasmus.villemoes@prevas.dk,
pbonzini@redhat.com, fenghua.yu@intel.com, xiaoyao.li@intel.com,
nadav.amit@gmail.com, thellstrom@vmware.com, tony.luck@intel.com,
rostedt@goodmis.org, gregkh@linuxfoundation.org,
jannh@google.com, keescook@chromium.org, David.Laight@aculab.com,
dcovelli@vmware.com, mhiramat@kernel.org
Subject: Re: [PATCH 0/4] x86/module: Out-of-tree module decode and sanitize
Date: Tue, 7 Apr 2020 21:41:12 +0200 [thread overview]
Message-ID: <20200407194112.GQ2452@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <a53a01b9-2907-4eb3-a9fd-16e6e8029028@citrix.com>
On Tue, Apr 07, 2020 at 06:23:27PM +0100, Andrew Cooper wrote:
> On 07/04/2020 12:02, Peter Zijlstra wrote:
> > Hi all,
> >
> > Driven by the SLD vs VMX interaction, here are some patches that provide means
> > to analyze the text of out-of-tree modules.
> >
> > The first user of that is refusing to load modules on VMX-SLD conflicts, but it
> > also has a second patch that refulses to load any module that tries to modify
> > CRn/DRn.
> >
> > I'm thinking people will quickly come up with more and more elaborate tests to
> > which to subject out-of-tree modules.
>
> Anything playing with LGDT & friends? Shouldn't be substantially more
> elaborate than CR/DR to check for.
More friends? (I wasn't sure on the Sxxx instructions, they appear
harmless, but what do I know..)
I was also eyeing LSL LTR LSS, none of which I figured a module has any
business of using. Are there more?
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -282,6 +282,50 @@ static bool insn_is_mov_DRn(struct insn
return false;
}
+static bool insn_is_LxDT(struct insn *insn)
+{
+ u8 modrm = insn->modrm.bytes[0];
+ u8 modrm_mod = X86_MODRM_MOD(modrm);
+ u8 modrm_reg = X86_MODRM_REG(modrm);
+
+ if (insn->opcode.bytes[0] != 0x0f)
+ return false;
+
+ switch (insn->opcode.bytes[1]) {
+ case 0x00:
+ if (modrm_mod != 0x03)
+ break;
+
+ switch (modrm_reg) {
+ case 0x0: /* SLDT */
+ case 0x2: /* LLDT */
+ return true;
+
+ default:
+ break;
+ }
+ break;
+
+ case 0x01:
+ switch (modrm_reg) {
+ case 0x0: /* SGDT */
+ case 0x1: /* SIDT */
+ case 0x2: /* LGDT */
+ case 0x3: /* LIDT */
+ return true;
+
+ default:
+ break;
+ }
+ break;
+
+ default:
+ break;
+ }
+
+ return false;
+}
+
static int decode_module(struct module *mod, void *text, void *text_end, bool sld_safe)
{
bool allow_vmx = sld_safe || !split_lock_enabled();
next prev parent reply other threads:[~2020-04-07 19:41 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-07 11:02 [PATCH 0/4] x86/module: Out-of-tree module decode and sanitize Peter Zijlstra
2020-04-07 11:02 ` [PATCH 1/4] module: Expose load_info to arch module loader code Peter Zijlstra
2020-04-07 16:52 ` Kees Cook
2020-04-07 11:02 ` [PATCH 2/4] module: Convert module_finalize() to load_info Peter Zijlstra
2020-04-07 16:53 ` Kees Cook
2020-04-07 11:02 ` [PATCH 3/4] x86,module: Detect VMX vs SLD conflicts Peter Zijlstra
2020-04-07 14:35 ` Greg KH
2020-04-07 14:44 ` Paolo Bonzini
2020-04-07 14:55 ` Greg KH
2020-04-07 14:49 ` Steven Rostedt
2020-04-07 15:24 ` Peter Zijlstra
2020-04-07 15:28 ` Paolo Bonzini
2020-04-07 15:44 ` Greg KH
2020-04-07 16:51 ` Masami Hiramatsu
2020-04-07 17:16 ` Andrew Cooper
2020-04-07 23:59 ` Masami Hiramatsu
2020-04-08 7:25 ` Masami Hiramatsu
2020-04-07 18:26 ` kbuild test robot
2020-04-07 21:25 ` David Laight
2020-04-07 23:15 ` Kees Cook
2020-04-08 2:10 ` Xiaoyao Li
2020-04-08 8:09 ` Masami Hiramatsu
2020-04-08 9:56 ` Peter Zijlstra
2020-04-08 10:15 ` Andrew Cooper
2020-04-10 11:25 ` Masami Hiramatsu
2020-04-07 11:02 ` [PATCH 4/4] x86,module: Detect CRn and DRn manipulation Peter Zijlstra
2020-04-07 17:01 ` Kees Cook
2020-04-07 18:13 ` Peter Zijlstra
2020-04-07 18:49 ` Kees Cook
2020-04-07 18:55 ` Nadav Amit
2020-04-07 19:38 ` Peter Zijlstra
2020-04-07 20:27 ` Nadav Amit
2020-04-07 20:50 ` Peter Zijlstra
2020-04-07 21:22 ` Nadav Amit
2020-04-07 21:27 ` Peter Zijlstra
2020-04-07 22:12 ` Paolo Bonzini
2020-04-07 23:51 ` Nadav Amit
2020-04-08 8:45 ` Peter Zijlstra
2020-04-08 5:18 ` Christoph Hellwig
2020-04-07 23:15 ` Andrew Cooper
2020-04-08 0:22 ` Paolo Bonzini
2020-04-08 8:37 ` Peter Zijlstra
2020-04-08 9:52 ` Andrew Cooper
2020-04-07 21:48 ` Steven Rostedt
2020-04-08 5:58 ` Jan Kiszka
2020-04-08 8:03 ` Paolo Bonzini
2020-04-08 8:58 ` Jan Kiszka
2020-04-08 9:04 ` Paolo Bonzini
2020-04-08 10:45 ` Jan Kiszka
2020-04-08 8:51 ` Peter Zijlstra
2020-04-08 8:59 ` Jan Kiszka
2020-04-08 9:25 ` David Laight
2020-04-08 11:13 ` Jan Kiszka
2020-04-08 11:17 ` David Laight
2020-04-08 9:13 ` Peter Zijlstra
2020-04-08 10:50 ` Jan Kiszka
2020-04-08 13:27 ` Steven Rostedt
2020-04-08 15:44 ` Peter Zijlstra
2020-04-08 15:46 ` Christoph Hellwig
2020-04-08 16:02 ` Sean Christopherson
2020-04-08 16:15 ` Paolo Bonzini
2020-04-09 8:56 ` Peter Zijlstra
2020-04-09 10:13 ` Nadav Amit
2020-04-09 21:13 ` Thomas Gleixner
2020-04-09 22:18 ` Steven Rostedt
2020-04-10 5:37 ` Nadav Amit
2020-04-08 15:54 ` Jessica Yu
2020-04-07 17:23 ` [PATCH 0/4] x86/module: Out-of-tree module decode and sanitize Andrew Cooper
2020-04-07 19:41 ` Peter Zijlstra [this message]
2020-04-07 20:11 ` Andrew Cooper
2020-04-07 20:45 ` Peter Zijlstra
2020-04-07 21:21 ` Andrew Cooper
2020-04-07 20:21 ` Andrew Cooper
2020-04-07 20:48 ` Peter Zijlstra
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