linux-kernel - [PATCH v25 4/9] x86/cet/ibt: Update ELF header parsing for Indirect Branch Tracking

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Message-Id: <20210415221734.32628-5-yu-cheng.yu@intel.com>
Date:   Thu, 15 Apr 2021 15:17:29 -0700
From:   Yu-cheng Yu <yu-cheng.yu@...el.com>
To:     x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-api@...r.kernel.org,
        Arnd Bergmann <arnd@...db.de>,
        Andy Lutomirski <luto@...nel.org>,
        Balbir Singh <bsingharora@...il.com>,
        Borislav Petkov <bp@...en8.de>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Eugene Syromiatnikov <esyr@...hat.com>,
        Florian Weimer <fweimer@...hat.com>,
        "H.J. Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>,
        Peter Zijlstra <peterz@...radead.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@...el.com>,
        Dave Martin <Dave.Martin@....com>,
        Weijiang Yang <weijiang.yang@...el.com>,
        Pengfei Xu <pengfei.xu@...el.com>,
        Haitao Huang <haitao.huang@...el.com>
Cc:     Yu-cheng Yu <yu-cheng.yu@...el.com>
Subject: [PATCH v25 4/9] x86/cet/ibt: Update ELF header parsing for Indirect Branch Tracking

An ELF file's .note.gnu.property indicates features the file supports.
The property is parsed at loading time and passed to arch_setup_elf_
property().  Update it for Indirect Branch Tracking.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@...el.com>
Cc: Kees Cook <keescook@...omium.org>
---
v24:
- Update for splitting shadow stack and ibt.

 arch/x86/Kconfig             | 2 ++
 arch/x86/kernel/process_64.c | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6bb69fba0dad..7436e3a608e8 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1970,6 +1970,8 @@ config X86_IBT
 	def_bool n
 	depends on X86_SHADOW_STACK
 	depends on $(cc-option,-fcf-protection)
+	select ARCH_USE_GNU_PROPERTY
+	select ARCH_BINFMT_ELF_STATE
 	help
 	  Indirect Branch Tracking (IBT) provides protection against
 	  CALL-/JMP-oriented programming attacks.  It is active when
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index d71045b29475..bf8ef10e5b78 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -864,6 +864,14 @@ int arch_setup_elf_property(struct arch_elf_state *state)
 			r = shstk_setup();
 	}
 
+	if (r < 0)
+		return r;
+
+	if (cpu_feature_enabled(X86_FEATURE_IBT)) {
+		if (state->gnu_property & GNU_PROPERTY_X86_FEATURE_1_IBT)
+			r = ibt_setup();
+	}
+
 	return r;
 }
 #endif
-- 
2.21.0