diff options
| author | Sean Christopherson <sean.j.christopherson@intel.com> | 2020-11-13 00:01:17 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2020-11-17 14:36:13 +0100 |
| commit | 74faeee06db81a06add0def6a394210c8fef0ab7 (patch) | |
| tree | c5287d2695d9aae8cbf0a784cb8a3fbb8e5e0007 /arch/x86/mm/fault.c | |
| parent | e7e0545299d8cb0fd6fe3ba50401b7f5c3937362 (diff) | |
x86/mm: Signal SIGSEGV with PF_SGX
The x86 architecture has a set of page fault error codes. These indicate
things like whether the fault occurred from a write, or whether it
originated in userspace.
The SGX hardware architecture has its own per-page memory management
metadata (EPCM) [*] and hardware which is separate from the normal x86 MMU.
The architecture has a new page fault error code: PF_SGX. This new error
code bit is set whenever a page fault occurs as the result of the SGX MMU.
These faults occur for a variety of reasons. For instance, an access
attempt to enclave memory from outside the enclave causes a PF_SGX fault.
PF_SGX would also be set for permission conflicts, such as if a write to an
enclave page occurs and the page is marked read-write in the x86 page
tables but is read-only in the EPCM.
These faults do not always indicate errors, though. SGX pages are
encrypted with a key that is destroyed at hardware reset, including
suspend. Throwing a SIGSEGV allows user space software to react and recover
when these events occur.
Include PF_SGX in the PF error codes list and throw SIGSEGV when it is
encountered.
[*] Intel SDM: 36.5.1 Enclave Page Cache Map (EPCM)
[ bp: Add bit 15 to the comment above enum x86_pf_error_code too. ]
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jethro Beekman <jethro@fortanix.com>
Link: https://lkml.kernel.org/r/20201112220135.165028-7-jarkko@kernel.org
Diffstat (limited to 'arch/x86/mm/fault.c')
| -rw-r--r-- | arch/x86/mm/fault.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 82bf37a5c9ec..9339fee83784 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1102,6 +1102,18 @@ access_error(unsigned long error_code, struct vm_area_struct *vma) return 1; /* + * SGX hardware blocked the access. This usually happens + * when the enclave memory contents have been destroyed, like + * after a suspend/resume cycle. In any case, the kernel can't + * fix the cause of the fault. Handle the fault as an access + * error even in cases where no actual access violation + * occurred. This allows userspace to rebuild the enclave in + * response to the signal. + */ + if (unlikely(error_code & X86_PF_SGX)) + return 1; + + /* * Make sure to check the VMA so that we do not perform * faults just to hit a X86_PF_PK as soon as we fill in a * page. |