diff options
| author | Andy Lutomirski <luto@amacapital.net> | 2014-10-25 02:58:12 +0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-02-04 14:10:47 +0300 |
| commit | 7911d3f7af14a614617e38245fedf98a724e46a9 (patch) | |
| tree | 8a8d163aee11daadeda7ecd9e835b86c2eb5890e /arch/x86/include/asm/mmu.h | |
| parent | c1317ec2b906442930318d9d6e51425c5a69e9cb (diff) | |
| download | linux-7911d3f7af14a614617e38245fedf98a724e46a9.tar.xz | |
perf/x86: Only allow rdpmc if a perf_event is mapped
We currently allow any process to use rdpmc. This significantly
weakens the protection offered by PR_TSC_DISABLED, and it could be
helpful to users attempting to exploit timing attacks.
Since we can't enable access to individual counters, use a very
coarse heuristic to limit access to rdpmc: allow access only when
a perf_event is mmapped. This protects seccomp sandboxes.
There is plenty of room to further tighen these restrictions. For
example, this allows rdpmc for any x86_pmu event, but it's only
useful for self-monitoring tasks.
As a side effect, cap_user_rdpmc will now be false for AMD uncore
events. This isn't a real regression, since .event_idx is disabled
for these events anyway for the time being. Whenever that gets
re-added, the cap_user_rdpmc code can be adjusted or refactored
accordingly.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Vince Weaver <vince@deater.net>
Cc: "hillf.zj" <hillf.zj@alibaba-inc.com>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/a2bdb3cf3a1d70c26980d7c6dddfbaa69f3182bf.1414190806.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/mmu.h')
| -rw-r--r-- | arch/x86/include/asm/mmu.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h index 876e74e8eec7..09b9620a73b4 100644 --- a/arch/x86/include/asm/mmu.h +++ b/arch/x86/include/asm/mmu.h @@ -19,6 +19,8 @@ typedef struct { struct mutex lock; void __user *vdso; + + atomic_t perf_rdpmc_allowed; /* nonzero if rdpmc is allowed */ } mm_context_t; #ifdef CONFIG_SMP |