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| author | Nadav Amit <namit@vmware.com> | 2019-04-25 17:11:30 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-09 09:17:24 +0200 |
| commit | ca309fef7a69b8e71e6c84b84b6b97fa2db19e9f (patch) | |
| tree | 715918be58214c7cd94c66e7d668975baf9fb46a /arch/x86 | |
| parent | b49ca4bf1b9c7e7c4e6ca046d1c76109e8a9d0e7 (diff) | |
| download | linux-rpi3-ca309fef7a69b8e71e6c84b84b6b97fa2db19e9f.tar.gz linux-rpi3-ca309fef7a69b8e71e6c84b84b6b97fa2db19e9f.tar.bz2 linux-rpi3-ca309fef7a69b8e71e6c84b84b6b97fa2db19e9f.zip | |
x86/kprobes: Set instruction page as executable
[ Upstream commit 7298e24f904224fa79eb8fd7e0fbd78950ccf2db ]
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 <namit@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.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/20190426001143.4983-11-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 544bc2dfe408..e83a057564d1 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); } |