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64 lines
2 KiB
Diff
64 lines
2 KiB
Diff
From 896ccdd6bccc7698324c19c013f8fedd72142484 Mon Sep 17 00:00:00 2001
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From: AKASHI Takahiro <takahiro.akashi@linaro.org>
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Date: Thu, 21 Aug 2014 17:56:40 +0900
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Subject: [PATCH 07/12] arm64: ptrace: add PTRACE_SET_SYSCALL
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To allow tracer to be able to change/skip a system call by re-writing
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a syscall number, there are several approaches:
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(1) modify x8 register with ptrace(PTRACE_SETREGSET), and handle this case
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later on in syscall_trace_enter(), or
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(2) support ptrace(PTRACE_SET_SYSCALL) as on arm
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Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to
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tracer as well as that secure_computing() expects a changed syscall number
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to be visible, especially case of -1, before this function returns in
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syscall_trace_enter(), we'd better take (2).
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Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
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Reviewed-by: Kees Cook <keescook@chromium.org>
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---
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arch/arm64/include/uapi/asm/ptrace.h | 1 +
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arch/arm64/kernel/ptrace.c | 14 +++++++++++++-
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2 files changed, 14 insertions(+), 1 deletion(-)
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diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h
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index c136fd53c847..164e2bbe9afd 100644
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--- a/arch/arm64/include/uapi/asm/ptrace.h
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+++ b/arch/arm64/include/uapi/asm/ptrace.h
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@@ -23,6 +23,7 @@
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#include <asm/hwcap.h>
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+#define PTRACE_SET_SYSCALL 23
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/*
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* PSR bits
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diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
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index 53bdc598d1c1..6ef1e17d9c5b 100644
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--- a/arch/arm64/kernel/ptrace.c
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+++ b/arch/arm64/kernel/ptrace.c
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@@ -1093,7 +1093,19 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task)
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long arch_ptrace(struct task_struct *child, long request,
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unsigned long addr, unsigned long data)
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{
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- return ptrace_request(child, request, addr, data);
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+ int ret;
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+
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+ switch (request) {
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+ case PTRACE_SET_SYSCALL:
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+ task_pt_regs(child)->syscallno = data;
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+ ret = 0;
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+ break;
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+ default:
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+ ret = ptrace_request(child, request, addr, data);
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+ break;
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+ }
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+
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+ return ret;
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}
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enum ptrace_syscall_dir {
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--
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2.19.0
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