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Message-ID: <tip-d0381c81c2f782fa2131178d11e0cfb23d50d631@git.kernel.org>
Date: Wed, 12 Apr 2017 00:34:35 -0700
From: tip-bot for Masami Hiramatsu <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: hpa@...or.com, tglx@...utronix.de, peterz@...radead.org,
torvalds@...ux-foundation.org, jpoimboe@...hat.com,
brgerst@...il.com, ananth@...ux.vnet.ibm.com,
linux-kernel@...r.kernel.org, dvlasenk@...hat.com,
xiaolong.ye@...el.com, mhiramat@...nel.org, mingo@...nel.org,
bp@...en8.de, anil.s.keshavamurthy@...el.com, davem@...emloft.net,
aryabinin@...tuozzo.com
Subject: [tip:perf/core] kprobes/x86: Set kprobes pages read-only
Commit-ID: d0381c81c2f782fa2131178d11e0cfb23d50d631
Gitweb: http://git.kernel.org/tip/d0381c81c2f782fa2131178d11e0cfb23d50d631
Author: Masami Hiramatsu <mhiramat@...nel.org>
AuthorDate: Wed, 29 Mar 2017 14:02:46 +0900
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 12 Apr 2017 09:23:46 +0200
kprobes/x86: Set kprobes pages read-only
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>
---
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 3f084a0..0dc24e6 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -419,6 +419,8 @@ static int arch_copy_kprobe(struct kprobe *p)
{
int len;
+ set_memory_rw((unsigned long)p->ainsn.insn & PAGE_MASK, 1);
+
/* Copy an instruction with recovering if other optprobe modifies it.*/
len = __copy_instruction(p->ainsn.insn, p->addr);
if (!len)
@@ -430,6 +432,8 @@ static int arch_copy_kprobe(struct kprobe *p)
*/
prepare_boost(p, len);
+ 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 3e7c6e5..b121037 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -350,6 +350,7 @@ 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);
@@ -372,6 +373,8 @@ 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);
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