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From: Deepak Gupta <debug@rivosinc.com>
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Subject: [PATCH v3 24/29] riscv/ptrace: riscv cfi status and state via ptrace and in core files
Date: Wed,  3 Apr 2024 16:35:12 -0700	[thread overview]
Message-ID: <20240403234054.2020347-25-debug@rivosinc.com> (raw)
In-Reply-To: <20240403234054.2020347-1-debug@rivosinc.com>

Expose a new register type NT_RISCV_USER_CFI for risc-v cfi status and
state. Intentionally both landing pad and shadow stack status and state
are rolled into cfi state. Creating two different NT_RISCV_USER_XXX would
not be useful and wastage of a note type. Enabling or disabling of feature
is not allowed via ptrace set interface. However setting `elp` state or
setting shadow stack pointer are allowed via ptrace set interface. It is
expected `gdb` might have use to fixup `elp` state or `shadow stack`
pointer.

Signed-off-by: Deepak Gupta <debug@rivosinc.com>
---
 arch/riscv/include/uapi/asm/ptrace.h | 18 ++++++
 arch/riscv/kernel/ptrace.c           | 83 ++++++++++++++++++++++++++++
 include/uapi/linux/elf.h             |  1 +
 3 files changed, 102 insertions(+)

diff --git a/arch/riscv/include/uapi/asm/ptrace.h b/arch/riscv/include/uapi/asm/ptrace.h
index a38268b19c3d..512be06a8661 100644
--- a/arch/riscv/include/uapi/asm/ptrace.h
+++ b/arch/riscv/include/uapi/asm/ptrace.h
@@ -127,6 +127,24 @@ struct __riscv_v_regset_state {
  */
 #define RISCV_MAX_VLENB (8192)
 
+struct __cfi_status {
+	/* indirect branch tracking state */
+	__u64 lp_en : 1;
+	__u64 lp_lock : 1;
+	__u64 elp_state : 1;
+
+	/* shadow stack status */
+	__u64 shstk_en : 1;
+	__u64 shstk_lock : 1;
+
+	__u64 rsvd : sizeof(__u64) - 5;
+};
+
+struct user_cfi_state {
+	struct __cfi_status	cfi_status;
+	__u64 shstk_ptr;
+};
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _UAPI_ASM_RISCV_PTRACE_H */
diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c
index e8515aa9d80b..33d4b32cc6a7 100644
--- a/arch/riscv/kernel/ptrace.c
+++ b/arch/riscv/kernel/ptrace.c
@@ -19,6 +19,7 @@
 #include <linux/regset.h>
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
+#include <asm/usercfi.h>
 
 enum riscv_regset {
 	REGSET_X,
@@ -28,6 +29,9 @@ enum riscv_regset {
 #ifdef CONFIG_RISCV_ISA_V
 	REGSET_V,
 #endif
+#ifdef CONFIG_RISCV_USER_CFI
+	REGSET_CFI,
+#endif
 };
 
 static int riscv_gpr_get(struct task_struct *target,
@@ -152,6 +156,75 @@ static int riscv_vr_set(struct task_struct *target,
 }
 #endif
 
+#ifdef CONFIG_RISCV_USER_CFI
+static int riscv_cfi_get(struct task_struct *target,
+			const struct user_regset *regset,
+			struct membuf to)
+{
+	struct user_cfi_state user_cfi;
+	struct pt_regs *regs;
+
+	regs = task_pt_regs(target);
+
+	user_cfi.cfi_status.lp_en = is_indir_lp_enabled(target);
+	user_cfi.cfi_status.lp_lock = is_indir_lp_locked(target);
+	user_cfi.cfi_status.elp_state = (regs->status & SR_ELP);
+
+	user_cfi.cfi_status.shstk_en = is_shstk_enabled(target);
+	user_cfi.cfi_status.shstk_lock = is_shstk_locked(target);
+	user_cfi.shstk_ptr = get_active_shstk(target);
+
+	return membuf_write(&to, &user_cfi, sizeof(user_cfi));
+}
+
+/*
+ * Does it make sense to allowing enable / disable of cfi via ptrace?
+ * Not allowing enable / disable / locking control via ptrace for now.
+ * Setting shadow stack pointer is allowed. GDB might use it to unwind or
+ * some other fixup. Similarly gdb might want to suppress elp and may want
+ * to reset elp state.
+ */
+static int riscv_cfi_set(struct task_struct *target,
+			const struct user_regset *regset,
+			unsigned int pos, unsigned int count,
+			const void *kbuf, const void __user *ubuf)
+{
+	int ret;
+	struct user_cfi_state user_cfi;
+	struct pt_regs *regs;
+
+	regs = task_pt_regs(target);
+
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &user_cfi, 0, -1);
+	if (ret)
+		return ret;
+
+	/*
+	 * Not allowing enabling or locking shadow stack or landing pad
+	 * There is no disabling of shadow stack or landing pad via ptrace
+	 * rsvd field should be set to zero so that if those fields are needed in future
+	 */
+	if (user_cfi.cfi_status.lp_en || user_cfi.cfi_status.lp_lock ||
+		user_cfi.cfi_status.shstk_en || user_cfi.cfi_status.shstk_lock ||
+		!user_cfi.cfi_status.rsvd)
+		return -EINVAL;
+
+	/* If lpad is enabled on target and ptrace requests to set / clear elp, do that */
+	if (is_indir_lp_enabled(target)) {
+		if (user_cfi.cfi_status.elp_state) /* set elp state */
+			regs->status |= SR_ELP;
+		else
+			regs->status &= ~SR_ELP; /* clear elp state */
+	}
+
+	/* If shadow stack enabled on target, set new shadow stack pointer */
+	if (is_shstk_enabled(target))
+		set_active_shstk(target, user_cfi.shstk_ptr);
+
+	return 0;
+}
+#endif
+
 static const struct user_regset riscv_user_regset[] = {
 	[REGSET_X] = {
 		.core_note_type = NT_PRSTATUS,
@@ -182,6 +255,16 @@ static const struct user_regset riscv_user_regset[] = {
 		.set = riscv_vr_set,
 	},
 #endif
+#ifdef CONFIG_RISCV_USER_CFI
+	[REGSET_CFI] = {
+		.core_note_type = NT_RISCV_USER_CFI,
+		.align = sizeof(__u64),
+		.n = sizeof(struct user_cfi_state) / sizeof(__u64),
+		.size = sizeof(__u64),
+		.regset_get = riscv_cfi_get,
+		.set = riscv_cfi_set,
+	}
+#endif
 };
 
 static const struct user_regset_view riscv_user_native_view = {
diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index 9417309b7230..f60b2de66b1c 100644
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -447,6 +447,7 @@ typedef struct elf64_shdr {
 #define NT_MIPS_MSA	0x802		/* MIPS SIMD registers */
 #define NT_RISCV_CSR	0x900		/* RISC-V Control and Status Registers */
 #define NT_RISCV_VECTOR	0x901		/* RISC-V vector registers */
+#define NT_RISCV_USER_CFI	0x902		/* RISC-V shadow stack state */
 #define NT_LOONGARCH_CPUCFG	0xa00	/* LoongArch CPU config registers */
 #define NT_LOONGARCH_CSR	0xa01	/* LoongArch control and status registers */
 #define NT_LOONGARCH_LSX	0xa02	/* LoongArch Loongson SIMD Extension registers */
-- 
2.43.2


  parent reply	other threads:[~2024-04-03 23:42 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-03 23:34 [PATCH v3 00/29] riscv control-flow integrity for usermode Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 01/29] riscv: envcfg save and restore on task switching Deepak Gupta
2024-05-09  0:10   ` Charlie Jenkins
2024-05-09 19:00     ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 02/29] riscv: define default value for envcfg for task Deepak Gupta
2024-05-10 22:33   ` Charlie Jenkins
2024-05-13 18:33     ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 03/29] riscv/Kconfig: enable HAVE_EXIT_THREAD for riscv Deepak Gupta
2024-05-10 22:36   ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 04/29] riscv: zicfilp / zicfiss in dt-bindings (extensions.yaml) Deepak Gupta
2024-04-10 11:58   ` Rob Herring
2024-04-10 21:37     ` Deepak Gupta
2024-04-15 19:41       ` Rob Herring
2024-04-16 15:44         ` Deepak Gupta
2024-05-09 18:14           ` Conor Dooley
2024-05-09 18:46             ` Deepak Gupta
2024-05-09 20:32               ` Conor Dooley
2024-05-09 23:26                 ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 05/29] riscv: zicfiss / zicfilp enumeration Deepak Gupta
2024-05-09  0:00   ` Andy Chiu
2024-05-09  0:07     ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 06/29] riscv: zicfiss / zicfilp extension csr and bit definitions Deepak Gupta
2024-05-10 22:37   ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 07/29] riscv: usercfi state for task and save/restore of CSR_SSP on trap entry/exit Deepak Gupta
2024-05-10 22:51   ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 08/29] mm: Define VM_SHADOW_STACK for RISC-V Deepak Gupta
2024-04-04 18:58   ` David Hildenbrand
2024-04-04 19:04     ` Mark Brown
2024-04-04 19:15       ` David Hildenbrand
2024-04-04 19:21         ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 09/29] mm: abstract shadow stack vma behind `vma_is_shadow_stack` Deepak Gupta
2024-04-04 19:02   ` David Hildenbrand
2024-04-04 21:39     ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 10/29] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE Deepak Gupta
2024-05-10 21:02   ` Charlie Jenkins
2024-05-13 17:47     ` Deepak Gupta
2024-05-13 18:36       ` Charlie Jenkins
2024-05-13 18:41         ` Deepak Gupta
2024-05-13 21:26           ` Charlie Jenkins
2024-05-12 16:24   ` Alexandre Ghiti
2024-05-13 18:29     ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 11/29] riscv mm: manufacture shadow stack pte Deepak Gupta
2024-05-12 16:26   ` Alexandre Ghiti
2024-04-03 23:35 ` [PATCH v3 12/29] riscv mmu: teach pte_mkwrite to manufacture shadow stack PTEs Deepak Gupta
2024-05-12 16:28   ` Alexandre Ghiti
2024-05-13 17:33     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 13/29] riscv mmu: write protect and shadow stack Deepak Gupta
2024-05-12 16:31   ` Alexandre Ghiti
2024-05-13 17:32     ` Deepak Gupta
2024-05-23 14:59       ` Alexandre Ghiti
2024-05-24  7:16         ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 14/29] riscv/mm: Implement map_shadow_stack() syscall Deepak Gupta
2024-05-12 16:50   ` Alexandre Ghiti
2024-05-13 17:25     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 15/29] riscv/shstk: If needed allocate a new shadow stack on clone Deepak Gupta
2024-05-12 17:05   ` Alexandre Ghiti
2024-05-13 17:10     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 16/29] prctl: arch-agnostic prctl for shadow stack Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 17/29] prctl: arch-agnostic prctl for indirect branch tracking Deepak Gupta
2024-05-10 23:29   ` Charlie Jenkins
2024-05-13 18:31     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 18/29] riscv: Implements arch agnostic shadow stack prctls Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 19/29] riscv: Implements arch agnostic indirect branch tracking prctls Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 20/29] riscv/kernel: update __show_regs to print shadow stack register Deepak Gupta
2024-05-12 17:10   ` Alexandre Ghiti
2024-04-03 23:35 ` [PATCH v3 21/29] riscv/traps: Introduce software check exception Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 22/29] riscv sigcontext: adding cfi state field in sigcontext Deepak Gupta
2024-05-24  9:46   ` Andy Chiu
2024-05-24 19:11     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 23/29] riscv signal: Save and restore of shadow stack for signal Deepak Gupta
2024-04-03 23:35 ` Deepak Gupta [this message]
2024-04-03 23:35 ` [PATCH v3 25/29] riscv/hwprobe: zicfilp / zicfiss enumeration in hwprobe Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 26/29] riscv: create a config for shadow stack and landing pad instr support Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 27/29] riscv: Documentation for landing pad / indirect branch tracking Deepak Gupta
2024-05-10 20:30   ` Charlie Jenkins
2024-05-13 17:07     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 28/29] riscv: Documentation for shadow stack on riscv Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 29/29] kselftest/riscv: kselftest for user mode cfi Deepak Gupta
2024-05-09 18:21   ` Charlie Jenkins
2024-05-09 19:16     ` Deepak Gupta
2024-05-10  1:20   ` Charlie Jenkins
2024-05-09  0:33 ` [PATCH v3 00/29] riscv control-flow integrity for usermode Charlie Jenkins

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