Commit-ID: 3c0dab44e22782359a0a706cbce72de99a22aa75 Gitweb: https://git.kernel.org/tip/3c0dab44e22782359a0a706cbce72de99a22aa75 Author: Nadav Amit <na...@vmware.com> AuthorDate: Thu, 25 Apr 2019 17:11:29 -0700 Committer: Ingo Molnar <mi...@kernel.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 <na...@vmware.com> Signed-off-by: Rick Edgecombe <rick.p.edgeco...@intel.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Reviewed-by: Steven Rostedt (VMware) <rost...@goodmis.org> Cc: <a...@linux-foundation.org> Cc: <ard.biesheu...@linaro.org> Cc: <deneen.t.d...@intel.com> Cc: <kernel-harden...@lists.openwall.com> Cc: <kris...@linux.intel.com> Cc: <linux_...@icloud.com> Cc: <will.dea...@arm.com> Cc: Andy Lutomirski <l...@kernel.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Dave Hansen <dave.han...@linux.intel.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Rik van Riel <r...@surriel.com> Cc: Thomas Gleixner <t...@linutronix.de> Link: https://lkml.kernel.org/r/20190426001143.4983-10-na...@vmware.com Signed-off-by: Ingo Molnar <mi...@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 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);
