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Message-ID: <tip-3c0dab44e22782359a0a706cbce72de99a22aa75@git.kernel.org>
Date: Tue, 30 Apr 2019 04:21:23 -0700
From: tip-bot for Nadav Amit <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: bp@...en8.de, linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com, luto@...nel.org,
ard.biesheuvel@...aro.org, akpm@...ux-foundation.org,
linux_dti@...oud.com, dave.hansen@...ux.intel.com, tglx@...utronix.de,
torvalds@...ux-foundation.org, rick.p.edgecombe@...el.com,
will.deacon@....com, rostedt@...dmis.org, namit@...are.com,
deneen.t.dock@...el.com, kristen@...ux.intel.com, peterz@...radead.org,
mingo@...nel.org, hpa@...or.com, riel@...riel.com
Subject: [tip:x86/mm] x86/ftrace: Set trampoline pages as executable
Commit-ID: 3c0dab44e22782359a0a706cbce72de99a22aa75
Gitweb: https://git.kernel.org/tip/3c0dab44e22782359a0a706cbce72de99a22aa75
Author: Nadav Amit <namit@...are.com>
AuthorDate: Thu, 25 Apr 2019 17:11:29 -0700
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 30 Apr 2019 12:37:53 +0200
x86/ftrace: Set trampoline pages as executable
Since alloc_module() will not set the pages as executable soon, set
ftrace trampoline pages as executable after they are allocated.
For the time being, do not change ftrace to use the text_poke()
interface. As a result, ftrace still breaks W^X.
Signed-off-by: Nadav Amit <namit@...are.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Cc: <akpm@...ux-foundation.org>
Cc: <ard.biesheuvel@...aro.org>
Cc: <deneen.t.dock@...el.com>
Cc: <kernel-hardening@...ts.openwall.com>
Cc: <kristen@...ux.intel.com>
Cc: <linux_dti@...oud.com>
Cc: <will.deacon@....com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Rik van Riel <riel@...riel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-10-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/kernel/ftrace.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index ef49517f6bb2..53ba1aa3a01f 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -730,6 +730,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
unsigned long end_offset;
unsigned long op_offset;
unsigned long offset;
+ unsigned long npages;
unsigned long size;
unsigned long retq;
unsigned long *ptr;
@@ -762,6 +763,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
return 0;
*tramp_size = size + RET_SIZE + sizeof(void *);
+ npages = DIV_ROUND_UP(*tramp_size, PAGE_SIZE);
/* Copy ftrace_caller onto the trampoline memory */
ret = probe_kernel_read(trampoline, (void *)start_offset, size);
@@ -806,6 +808,12 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
/* ALLOC_TRAMP flags lets us know we created it */
ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
+ /*
+ * Module allocation needs to be completed by making the page
+ * executable. The page is still writable, which is a security hazard,
+ * but anyhow ftrace breaks W^X completely.
+ */
+ set_memory_x((unsigned long)trampoline, npages);
return (unsigned long)trampoline;
fail:
tramp_free(trampoline, *tramp_size);
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