| From 1b754451ecfacc12184af1eb771ee40eb94fab76 Mon Sep 17 00:00:00 2001 |
| From: Nadav Amit <namit@vmware.com> |
| Date: Thu, 25 Apr 2019 17:11:29 -0700 |
| Subject: x86/ftrace: Set trampoline pages as executable |
| |
| [ Upstream commit 3c0dab44e22782359a0a706cbce72de99a22aa75 ] |
| |
| 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@vmware.com> |
| Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> |
| Cc: <akpm@linux-foundation.org> |
| Cc: <ard.biesheuvel@linaro.org> |
| Cc: <deneen.t.dock@intel.com> |
| Cc: <kernel-hardening@lists.openwall.com> |
| Cc: <kristen@linux.intel.com> |
| Cc: <linux_dti@icloud.com> |
| Cc: <will.deacon@arm.com> |
| Cc: Andy Lutomirski <luto@kernel.org> |
| Cc: Borislav Petkov <bp@alien8.de> |
| Cc: Dave Hansen <dave.hansen@linux.intel.com> |
| Cc: H. Peter Anvin <hpa@zytor.com> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: Rik van Riel <riel@surriel.com> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Link: https://lkml.kernel.org/r/20190426001143.4983-10-namit@vmware.com |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.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 bd553b3af22e9..6e0c0ed8e4bf4 100644 |
| --- a/arch/x86/kernel/ftrace.c |
| +++ b/arch/x86/kernel/ftrace.c |
| @@ -749,6 +749,7 @@ 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; |
| @@ -781,6 +782,7 @@ 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); |
| @@ -825,6 +827,12 @@ 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); |
| -- |
| 2.20.1 |
| |