From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 30 Apr 2019 04:22:06 -0700 Sender: tip tree robot From: tip-bot for Nadav Amit Message-ID: In-Reply-To: <20190426001143.4983-11-namit@vmware.com> References: <20190426001143.4983-11-namit@vmware.com> Subject: [tip:x86/mm] x86/kprobes: Set instruction page as executable MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline To: linux-tip-commits@vger.kernel.org Cc: peterz@infradead.org, namit@vmware.com, mingo@kernel.org, akpm@linux-foundation.org, tglx@linutronix.de, rick.p.edgecombe@intel.com, hpa@zytor.com, ard.biesheuvel@linaro.org, dave.hansen@linux.intel.com, torvalds@linux-foundation.org, kristen@linux.intel.com, linux_dti@icloud.com, bp@alien8.de, deneen.t.dock@intel.com, riel@surriel.com, luto@kernel.org, will.deacon@arm.com, kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org List-ID: Commit-ID: 7298e24f904224fa79eb8fd7e0fbd78950ccf2db Gitweb: https://git.kernel.org/tip/7298e24f904224fa79eb8fd7e0fbd78950ccf2db Author: Nadav Amit AuthorDate: Thu, 25 Apr 2019 17:11:30 -0700 Committer: Ingo Molnar CommitDate: Tue, 30 Apr 2019 12:37:54 +0200 x86/kprobes: Set instruction page as executable Set the page as executable after allocation. This patch is a preparatory patch for a following patch that makes module allocated pages non-executable. While at it, do some small cleanup of what appears to be unnecessary masking. Signed-off-by: Nadav Amit Signed-off-by: Rick Edgecombe Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Cc: Cc: Cc: Cc: Cc: Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Rik van Riel Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20190426001143.4983-11-namit@vmware.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/kprobes/core.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index fed46ddb1eef..06058c44ab57 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -431,8 +431,20 @@ void *alloc_insn_page(void) void *page; page = module_alloc(PAGE_SIZE); - if (page) - set_memory_ro((unsigned long)page & PAGE_MASK, 1); + if (!page) + return NULL; + + /* + * First make the page read-only, and only then make it executable to + * prevent it from being W+X in between. + */ + set_memory_ro((unsigned long)page, 1); + + /* + * TODO: Once additional kernel code protection mechanisms are set, ensure + * that the page was not maliciously altered and it is still zeroed. + */ + set_memory_x((unsigned long)page, 1); return page; } @@ -440,8 +452,12 @@ void *alloc_insn_page(void) /* Recover page to RW mode before releasing it */ void free_insn_page(void *page) { - set_memory_nx((unsigned long)page & PAGE_MASK, 1); - set_memory_rw((unsigned long)page & PAGE_MASK, 1); + /* + * First make the page non-executable, and only then make it writable to + * prevent it from being W+X in between. + */ + set_memory_nx((unsigned long)page, 1); + set_memory_rw((unsigned long)page, 1); module_memfree(page); }