| Message ID | 20191122022406.590141-1-pasha.tatashin@soleen.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Use C inlines for uaccess | expand |
Kees Cook mentioned that it is a good idea to assert the PAN state during disable/enable. Since, with this change everything is moved to the same C place, if this hardening is something others also want to see, I could add it in the next revision of this series. Here are the options to choose from: 1. Do something similar to what is done in preempt with CONFIG_PREEMPT_COUNT: keep a boolean (could be optionally enabled by a config) that is checked when uaccess_enable()/uaccess_disable() are called. This way we will always check that state even on processors with hardware PAN and UAO, however, there is going to be this extra overhead of checking/storing the variable on userland enter/exits even on systems which have these marcos set to nothing otherwise. 2. Check only in __uaccess_ttbr0_disable()/__uaccess_ttbr0_enable() that ttbr0_el1 is in the expected state, or add another boolean for this purpose to thread_info. 3. Keep as is, and do not add extra overhead for this hardening. Thank you, Pasha On Thu, Nov 21, 2019 at 9:24 PM Pavel Tatashin <pasha.tatashin@soleen.com> wrote: > > Changelog > v2: > - Addressed Russell King's concern by not adding > uaccess_* to ARM. > - Removed the accidental change to xtensa > > Convert the remaining uaccess_* calls from ASM macros to C inlines. > > These patches apply against linux-next. I boot tested ARM64, and > compile tested ARM changes. > > Pavel Tatashin (3): > arm/arm64/xen: use C inlines for privcmd_call > arm64: remove uaccess_ttbr0 asm macros from cache functions > arm64: remove the rest of asm-uaccess.h > > arch/arm/include/asm/assembler.h | 2 +- > arch/arm/include/asm/xen/hypercall.h | 10 +++++ > arch/arm/xen/enlighten.c | 2 +- > arch/arm/xen/hypercall.S | 4 +- > arch/arm64/include/asm/asm-uaccess.h | 60 -------------------------- > arch/arm64/include/asm/cacheflush.h | 38 ++++++++++++++-- > arch/arm64/include/asm/xen/hypercall.h | 28 ++++++++++++ > arch/arm64/kernel/entry.S | 6 +-- > arch/arm64/lib/clear_user.S | 2 +- > arch/arm64/lib/copy_from_user.S | 2 +- > arch/arm64/lib/copy_in_user.S | 2 +- > arch/arm64/lib/copy_to_user.S | 2 +- > arch/arm64/mm/cache.S | 31 +++++-------- > arch/arm64/mm/context.c | 12 ++++++ > arch/arm64/mm/flush.c | 2 +- > arch/arm64/xen/hypercall.S | 19 +------- > include/xen/arm/hypercall.h | 12 +++--- > 17 files changed, 115 insertions(+), 119 deletions(-) > delete mode 100644 arch/arm64/include/asm/asm-uaccess.h > > -- > 2.24.0 >