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

From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Andy Lutomirski <luto@kernel.org>,
	Balbir Singh <bsingharora@gmail.com>,
	Borislav Petkov <bp@alien8.de>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Eugene Syromiatnikov <esyr@redhat.com>,
	Florian Weimer <fweimer@redhat.com>,
	"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Kees Cook <keescook@chromium.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Nadav Amit <nadav.amit@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Weijiang Yang <weijiang.yang@intel.com>,
	Pengfei Xu <pengfei.xu@intel.com>,
	Haitao Huang <haitao.huang@intel.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v25 4/9] x86/cet/ibt: Update ELF header parsing for Indirect Branch Tracking
Date: Thu, 15 Apr 2021 15:17:29 -0700	[thread overview]
Message-ID: <20210415221734.32628-5-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20210415221734.32628-1-yu-cheng.yu@intel.com>

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@intel.com>
Cc: Kees Cook <keescook@chromium.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

