From: Nadav Amit <nadav.amit@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>,
Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Damian Tometzki <linux_dti@icloud.com>,
linux-integrity <linux-integrity@vger.kernel.org>,
LSM List <linux-security-module@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Linux-MM <linux-mm@kvack.org>, Will Deacon <will.deacon@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Kristen Carlson Accardi <kristen@linux.intel.com>,
deneen.t.dock@intel.com
Subject: Re: [PATCH 08/17] x86/ftrace: set trampoline pages as executable
Date: Wed, 6 Feb 2019 09:33:35 -0800 [thread overview]
Message-ID: <5DFA1E3C-A335-4C4B-A86F-904A6CF6D871@gmail.com> (raw)
In-Reply-To: <20190206112213.2ec9dd5c@gandalf.local.home>
> On Feb 6, 2019, at 8:22 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed, 16 Jan 2019 16:32:50 -0800
> Rick Edgecombe <rick.p.edgecombe@intel.com> wrote:
>
>> From: Nadav Amit <namit@vmware.com>
>>
>> Since alloc_module() will not set the pages as executable soon, we need
>> to do so for ftrace trampoline pages after they are allocated.
>>
>> For the time being, we do not change ftrace to use the text_poke()
>> interface. As a result, ftrace breaks still breaks W^X.
>>
>> Cc: Steven Rostedt <rostedt@goodmis.org>
>> Signed-off-by: Nadav Amit <namit@vmware.com>
>> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
>> ---
>> arch/x86/kernel/ftrace.c | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>>
>> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
>> index 8257a59704ae..eb4a1937e72c 100644
>> --- a/arch/x86/kernel/ftrace.c
>> +++ b/arch/x86/kernel/ftrace.c
>> @@ -742,6 +742,7 @@ 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;
>> @@ -774,6 +775,7 @@ 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);
>> @@ -818,6 +820,13 @@ 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.
>> + */
>
> Perhaps we should set the page to non writable after the page is
> updated? And set it to writable only when we need to update it.
You remember that I sent you a patch that changed all these writes into
text_poke() and you said that I should defer it until this series is merged?
> As for this patch:
>
> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Thanks!
next prev parent reply other threads:[~2019-02-06 17:33 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-17 0:32 [PATCH 00/17] Merge text_poke fixes and executable lockdowns Rick Edgecombe
2019-01-17 0:32 ` [PATCH 01/17] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Rick Edgecombe
2019-01-17 6:47 ` Masami Hiramatsu
2019-01-17 21:15 ` hpa
2019-01-17 22:39 ` Nadav Amit
2019-01-17 22:59 ` hpa
2019-01-17 23:14 ` Nadav Amit
2019-01-17 23:19 ` H. Peter Anvin
2019-01-18 2:40 ` Nadav Amit
2019-01-25 9:30 ` Borislav Petkov
2019-01-25 18:28 ` Nadav Amit
2019-01-17 0:32 ` [PATCH 02/17] x86/jump_label: Use text_poke_early() during early init Rick Edgecombe
2019-01-17 0:32 ` [PATCH 03/17] x86/mm: temporary mm struct Rick Edgecombe
2019-01-17 0:32 ` [PATCH 04/17] fork: provide a function for copying init_mm Rick Edgecombe
2019-01-17 0:32 ` [PATCH 05/17] x86/alternative: initializing temporary mm for patching Rick Edgecombe
2019-01-17 0:32 ` [PATCH 06/17] x86/alternative: use temporary mm for text poking Rick Edgecombe
2019-01-17 20:27 ` Andy Lutomirski
2019-01-17 20:47 ` Andy Lutomirski
2019-01-17 21:43 ` Nadav Amit
2019-01-17 22:29 ` Nadav Amit
2019-01-17 22:31 ` hpa
2019-01-17 0:32 ` [PATCH 07/17] x86/kgdb: avoid redundant comparison of patched code Rick Edgecombe
2019-01-17 0:32 ` [PATCH 08/17] x86/ftrace: set trampoline pages as executable Rick Edgecombe
2019-02-06 16:22 ` Steven Rostedt
2019-02-06 17:33 ` Nadav Amit [this message]
2019-02-06 17:41 ` Steven Rostedt
2019-01-17 0:32 ` [PATCH 09/17] x86/kprobes: Instruction pages initialization enhancements Rick Edgecombe
2019-01-17 6:51 ` Masami Hiramatsu
2019-01-17 0:32 ` [PATCH 10/17] x86: avoid W^X being broken during modules loading Rick Edgecombe
2019-01-17 0:32 ` [PATCH 11/17] x86/jump-label: remove support for custom poker Rick Edgecombe
2019-01-17 0:32 ` [PATCH 12/17] x86/alternative: Remove the return value of text_poke_*() Rick Edgecombe
2019-01-17 0:32 ` [PATCH 13/17] Add set_alias_ function and x86 implementation Rick Edgecombe
2019-01-17 0:32 ` [PATCH 14/17] mm: Make hibernate handle unmapped pages Rick Edgecombe
2019-01-17 9:39 ` Pavel Machek
2019-01-17 22:16 ` Edgecombe, Rick P
2019-01-17 23:41 ` Pavel Machek
2019-01-17 23:48 ` Edgecombe, Rick P
2019-01-18 8:16 ` Pavel Machek
2019-01-17 0:32 ` [PATCH 15/17] vmalloc: New flags for safe vfree on special perms Rick Edgecombe
2019-01-17 0:32 ` [PATCH 16/17] Plug in new special vfree flag Rick Edgecombe
2019-02-06 16:23 ` Steven Rostedt
2019-02-07 17:33 ` Edgecombe, Rick P
2019-02-07 17:49 ` Steven Rostedt
2019-02-07 18:20 ` Edgecombe, Rick P
2019-01-17 0:32 ` [PATCH 17/17] module: Prevent module removal racing with text_poke() Rick Edgecombe
2019-01-17 7:54 ` Masami Hiramatsu
2019-01-17 18:07 ` Nadav Amit
2019-01-17 23:44 ` H. Peter Anvin
2019-01-18 8:23 ` Masami Hiramatsu
2019-01-17 23:58 ` H. Peter Anvin
2019-01-18 1:15 ` Nadav Amit
2019-01-18 13:32 ` Masami Hiramatsu
2019-01-17 13:21 ` [PATCH 00/17] Merge text_poke fixes and executable lockdowns Peter Zijlstra
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