lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20240403234054.2020347-18-debug@rivosinc.com>
Date: Wed,  3 Apr 2024 16:35:05 -0700
From: Deepak Gupta <debug@...osinc.com>
To: paul.walmsley@...ive.com,
	rick.p.edgecombe@...el.com,
	broonie@...nel.org,
	Szabolcs.Nagy@....com,
	kito.cheng@...ive.com,
	keescook@...omium.org,
	ajones@...tanamicro.com,
	conor.dooley@...rochip.com,
	cleger@...osinc.com,
	atishp@...shpatra.org,
	alex@...ti.fr,
	bjorn@...osinc.com,
	alexghiti@...osinc.com,
	samuel.holland@...ive.com,
	conor@...nel.org
Cc: linux-doc@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-mm@...ck.org,
	linux-arch@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	corbet@....net,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	robh+dt@...nel.org,
	krzysztof.kozlowski+dt@...aro.org,
	oleg@...hat.com,
	akpm@...ux-foundation.org,
	arnd@...db.de,
	ebiederm@...ssion.com,
	Liam.Howlett@...cle.com,
	vbabka@...e.cz,
	lstoakes@...il.com,
	shuah@...nel.org,
	brauner@...nel.org,
	debug@...osinc.com,
	andy.chiu@...ive.com,
	jerry.shih@...ive.com,
	hankuan.chen@...ive.com,
	greentime.hu@...ive.com,
	evan@...osinc.com,
	xiao.w.wang@...el.com,
	charlie@...osinc.com,
	apatel@...tanamicro.com,
	mchitale@...tanamicro.com,
	dbarboza@...tanamicro.com,
	sameo@...osinc.com,
	shikemeng@...weicloud.com,
	willy@...radead.org,
	vincent.chen@...ive.com,
	guoren@...nel.org,
	samitolvanen@...gle.com,
	songshuaishuai@...ylab.org,
	gerg@...nel.org,
	heiko@...ech.de,
	bhe@...hat.com,
	jeeheng.sia@...rfivetech.com,
	cyy@...self.name,
	maskray@...gle.com,
	ancientmodern4@...il.com,
	mathis.salmen@...sal.de,
	cuiyunhui@...edance.com,
	bgray@...ux.ibm.com,
	mpe@...erman.id.au,
	baruch@...s.co.il,
	alx@...nel.org,
	david@...hat.com,
	catalin.marinas@....com,
	revest@...omium.org,
	josh@...htriplett.org,
	shr@...kernel.io,
	deller@....de,
	omosnace@...hat.com,
	ojeda@...nel.org,
	jhubbard@...dia.com
Subject: [PATCH v3 17/29] prctl: arch-agnostic prctl for indirect branch tracking

Three architectures (x86, aarch64, riscv) have support for indirect branch
tracking feature in a very similar fashion. On a very high level, indirect
branch tracking is a CPU feature where CPU tracks branches which uses
memory operand to perform control transfer in program. As part of this
tracking on indirect branches, CPU goes in a state where it expects a
landing pad instr on target and if not found then CPU raises some fault
(architecture dependent)

x86 landing pad instr - `ENDBRANCH`
aarch64 landing pad instr - `BTI`
riscv landing instr - `lpad`

Given that three major arches have support for indirect branch tracking,
This patch makes `prctl` for indirect branch tracking arch agnostic.

To allow userspace to enable this feature for itself, following prtcls are
defined:
 - PR_GET_INDIR_BR_LP_STATUS: Gets current configured status for indirect
   branch tracking.
 - PR_SET_INDIR_BR_LP_STATUS: Sets a configuration for indirect branch
   tracking.
   Following status options are allowed
       - PR_INDIR_BR_LP_ENABLE: Enables indirect branch tracking on user
         thread.
       - PR_INDIR_BR_LP_DISABLE; Disables indirect branch tracking on user
         thread.
 - PR_LOCK_INDIR_BR_LP_STATUS: Locks configured status for indirect branch
   tracking for user thread.

Signed-off-by: Deepak Gupta <debug@...osinc.com>
---
 include/uapi/linux/prctl.h | 27 +++++++++++++++++++++++++++
 kernel/sys.c               | 30 ++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index 3c66ed8f46d8..b7a8212a068e 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -328,4 +328,31 @@ struct prctl_mm_map {
  */
 #define PR_LOCK_SHADOW_STACK_STATUS      73
 
+/*
+ * Get the current indirect branch tracking configuration for the current
+ * thread, this will be the value configured via PR_SET_INDIR_BR_LP_STATUS.
+ */
+#define PR_GET_INDIR_BR_LP_STATUS      74
+
+/*
+ * Set the indirect branch tracking configuration. PR_INDIR_BR_LP_ENABLE will
+ * enable cpu feature for user thread, to track all indirect branches and ensure
+ * they land on arch defined landing pad instruction.
+ * x86 - If enabled, an indirect branch must land on `ENDBRANCH` instruction.
+ * arch64 - If enabled, an indirect branch must land on `BTI` instruction.
+ * riscv - If enabled, an indirect branch must land on `lpad` instruction.
+ * PR_INDIR_BR_LP_DISABLE will disable feature for user thread and indirect
+ * branches will no more be tracked by cpu to land on arch defined landing pad
+ * instruction.
+ */
+#define PR_SET_INDIR_BR_LP_STATUS      75
+# define PR_INDIR_BR_LP_ENABLE		   (1UL << 0)
+
+/*
+ * Prevent further changes to the specified indirect branch tracking
+ * configuration.  All bits may be locked via this call, including
+ * undefined bits.
+ */
+#define PR_LOCK_INDIR_BR_LP_STATUS      76
+
 #endif /* _LINUX_PRCTL_H */
diff --git a/kernel/sys.c b/kernel/sys.c
index 242e9f147791..c770060c3f06 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2330,6 +2330,21 @@ int __weak arch_lock_shadow_stack_status(struct task_struct *t, unsigned long st
 	return -EINVAL;
 }
 
+int __weak arch_get_indir_br_lp_status(struct task_struct *t, unsigned long __user *status)
+{
+	return -EINVAL;
+}
+
+int __weak arch_set_indir_br_lp_status(struct task_struct *t, unsigned long __user *status)
+{
+	return -EINVAL;
+}
+
+int __weak arch_lock_indir_br_lp_status(struct task_struct *t, unsigned long __user *status)
+{
+	return -EINVAL;
+}
+
 #define PR_IO_FLUSHER (PF_MEMALLOC_NOIO | PF_LOCAL_THROTTLE)
 
 #ifdef CONFIG_ANON_VMA_NAME
@@ -2787,6 +2802,21 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 			return -EINVAL;
 		error = arch_lock_shadow_stack_status(me, arg2);
 		break;
+	case PR_GET_INDIR_BR_LP_STATUS:
+		if (arg3 || arg4 || arg5)
+			return -EINVAL;
+		error = arch_get_indir_br_lp_status(me, (unsigned long __user *) arg2);
+		break;
+	case PR_SET_INDIR_BR_LP_STATUS:
+		if (arg3 || arg4 || arg5)
+			return -EINVAL;
+		error = arch_set_indir_br_lp_status(me, (unsigned long __user *) arg2);
+		break;
+	case PR_LOCK_INDIR_BR_LP_STATUS:
+		if (arg3 || arg4 || arg5)
+			return -EINVAL;
+		error = arch_lock_indir_br_lp_status(me, (unsigned long __user *) arg2);
+		break;
 	default:
 		error = -EINVAL;
 		break;
-- 
2.43.2


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ