From: nadav.amit@gmail.com
To: Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com,
Thomas Gleixner <tglx@linutronix.de>,
Nadav Amit <nadav.amit@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
linux_dti@icloud.com, linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org, akpm@linux-foundation.org,
kernel-hardening@lists.openwall.com, linux-mm@kvack.org,
will.deacon@arm.com, ard.biesheuvel@linaro.org,
kristen@linux.intel.com, deneen.t.dock@intel.com,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Nadav Amit <namit@vmware.com>
Subject: [PATCH v6 11/24] x86/kprobes: Set instruction page as executable
Date: Fri, 26 Apr 2019 16:22:50 -0700 [thread overview]
Message-ID: <20190426232303.28381-12-nadav.amit@gmail.com> (raw)
In-Reply-To: <20190426232303.28381-1-nadav.amit@gmail.com>
From: Nadav Amit <namit@vmware.com>
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.
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
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 a034cb808e7e..1591852d3ac4 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);
}
--
2.17.1
next prev parent reply other threads:[~2019-04-27 6:44 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-26 23:22 [PATCH v6 00/24] x86: text_poke() fixes and executable lockdowns nadav.amit
2019-04-26 23:22 ` [PATCH v6 01/24] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" nadav.amit
2019-04-26 23:22 ` [PATCH v6 02/24] x86/jump_label: Use text_poke_early() during early init nadav.amit
2019-04-26 23:22 ` [PATCH v6 03/24] x86/mm: Introduce temporary mm structs nadav.amit
2019-04-26 23:22 ` [PATCH v6 04/24] x86/mm: Save debug registers when loading a temporary mm nadav.amit
2019-04-26 23:22 ` [PATCH v6 05/24] uprobes: Initialize uprobes earlier nadav.amit
2019-04-30 11:17 ` [tip:x86/mm] " tip-bot for Nadav Amit
2019-04-26 23:22 ` [PATCH v6 06/24] fork: Provide a function for copying init_mm nadav.amit
2019-04-26 23:22 ` [PATCH v6 07/24] x86/alternative: Initialize temporary mm for patching nadav.amit
2019-04-30 11:19 ` [tip:x86/mm] x86/alternatives: " tip-bot for Nadav Amit
2019-04-26 23:22 ` [PATCH v6 08/24] x86/alternative: Use temporary mm for text poking nadav.amit
2019-04-26 23:22 ` [PATCH v6 09/24] x86/kgdb: Avoid redundant comparison of patched code nadav.amit
2019-04-26 23:22 ` [PATCH v6 10/24] x86/ftrace: Set trampoline pages as executable nadav.amit
2019-04-26 23:22 ` nadav.amit [this message]
2019-04-26 23:22 ` [PATCH v6 12/24] x86/module: Avoid breaking W^X while loading modules nadav.amit
2019-04-26 23:22 ` [PATCH v6 13/24] x86/jump-label: Remove support for custom poker nadav.amit
2019-04-26 23:22 ` [PATCH v6 14/24] x86/alternative: Remove the return value of text_poke_*() nadav.amit
2019-04-26 23:22 ` [PATCH v6 15/24] x86/mm/cpa: Add set_direct_map_ functions nadav.amit
2019-04-26 23:22 ` [PATCH v6 16/24] mm: Make hibernate handle unmapped pages nadav.amit
2019-04-26 23:22 ` [PATCH v6 17/24] vmalloc: Add flag for free of special permsissions nadav.amit
2019-04-26 23:22 ` [PATCH v6 18/24] modules: Use vmalloc special flag nadav.amit
2019-04-26 23:22 ` [PATCH v6 19/24] bpf: " nadav.amit
2019-04-26 23:22 ` [PATCH v6 20/24] x86/ftrace: " nadav.amit
2019-04-26 23:23 ` [PATCH v6 21/24] x86/kprobes: " nadav.amit
2019-04-26 23:23 ` [PATCH v6 22/24] x86/alternative: Comment about module removal races nadav.amit
2019-04-26 23:23 ` [PATCH v6 23/24] mm/tlb: Provide default nmi_uaccess_okay() nadav.amit
2019-04-26 23:23 ` [PATCH v6 24/24] bpf: Fail bpf_probe_write_user() while mm is switched nadav.amit
2019-04-27 10:22 ` [PATCH v6 00/24] x86: text_poke() fixes and executable lockdowns Ingo Molnar
2019-04-27 10:32 ` Peter Zijlstra
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