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Message-ID: <20180308050023.8548-8-alexander.levin@microsoft.com>
Date: Thu, 8 Mar 2018 05:01:11 +0000
From: Sasha Levin <Alexander.Levin@...rosoft.com>
To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"stable@...r.kernel.org" <stable@...r.kernel.org>
CC: Masami Hiramatsu <mhiramat@...nel.org>,
Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
Borislav Petkov <bp@...en8.de>,
Brian Gerst <brgerst@...il.com>,
"David S . Miller" <davem@...emloft.net>,
Denys Vlasenko <dvlasenk@...hat.com>,
"H . Peter Anvin" <hpa@...or.com>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ye Xiaolong <xiaolong.ye@...el.com>,
Ingo Molnar <mingo@...nel.org>,
Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.4 008/101] kprobes/x86: Set kprobes pages
read-only
From: Masami Hiramatsu <mhiramat@...nel.org>
[ Upstream commit d0381c81c2f782fa2131178d11e0cfb23d50d631 ]
Set the pages which is used for kprobes' singlestep buffer
and optprobe's trampoline instruction buffer to readonly.
This can prevent unexpected (or unintended) instruction
modification.
This also passes rodata_test as below.
Without this patch, rodata_test shows a warning:
WARNING: CPU: 0 PID: 1 at arch/x86/mm/dump_pagetables.c:235 note_page+0x7a9/0xa20
x86/mm: Found insecure W+X mapping at address ffffffffa0000000/0xffffffffa0000000
With this fix, no W+X pages are found:
x86/mm: Checked W+X mappings: passed, no W+X pages found.
rodata_test: all tests were successful
Reported-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: David S . Miller <davem@...emloft.net>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ye Xiaolong <xiaolong.ye@...el.com>
Link: http://lkml.kernel.org/r/149076375592.22469.14174394514338612247.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
arch/x86/kernel/kprobes/core.c | 4 ++++
arch/x86/kernel/kprobes/opt.c | 3 +++
2 files changed, 7 insertions(+)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 5d11d01f75de..565e24e9ddf2 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -406,6 +406,8 @@ static int arch_copy_kprobe(struct kprobe *p)
{
int ret;
+ set_memory_rw((unsigned long)p->ainsn.insn & PAGE_MASK, 1);
+
/* Copy an instruction with recovering if other optprobe modifies it.*/
ret = __copy_instruction(p->ainsn.insn, p->addr);
if (!ret)
@@ -420,6 +422,8 @@ static int arch_copy_kprobe(struct kprobe *p)
else
p->ainsn.boostable = -1;
+ set_memory_ro((unsigned long)p->ainsn.insn & PAGE_MASK, 1);
+
/* Check whether the instruction modifies Interrupt Flag or not */
p->ainsn.if_modifier = is_IF_modifier(p->ainsn.insn);
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index ea8e2b846101..7aba9d6475a5 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -370,6 +370,7 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
}
buf = (u8 *)op->optinsn.insn;
+ set_memory_rw((unsigned long)buf & PAGE_MASK, 1);
/* Copy instructions into the out-of-line buffer */
ret = copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr);
@@ -392,6 +393,8 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
synthesize_reljump(buf + TMPL_END_IDX + op->optinsn.size,
(u8 *)op->kp.addr + op->optinsn.size);
+ set_memory_ro((unsigned long)buf & PAGE_MASK, 1);
+
flush_icache_range((unsigned long) buf,
(unsigned long) buf + TMPL_END_IDX +
op->optinsn.size + RELATIVEJUMP_SIZE);
--
2.14.1
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