On 07/07/2016 12:25 AM, Kees Cook wrote: > Hi, > > This is a start of the mainline port of PAX_USERCOPY[1]. After I started > writing tests (now in lkdtm in -next) for Casey's earlier port[2], I > kept tweaking things further and further until I ended up with a whole > new patch series. To that end, I took Rik's feedback and made a number > of other changes and clean-ups as well. > > Based on my understanding, PAX_USERCOPY was designed to catch a few > classes of flaws around the use of copy_to_user()/copy_from_user(). These > changes don't touch get_user() and put_user(), since these operate on > constant sized lengths, and tend to be much less vulnerable. There > are effectively three distinct protections in the whole series, > each of which I've given a separate CONFIG, though this patch set is > only the first of the three intended protections. (Generally speaking, > PAX_USERCOPY covers what I'm calling CONFIG_HARDENED_USERCOPY (this) and > CONFIG_HARDENED_USERCOPY_WHITELIST (future), and PAX_USERCOPY_SLABS covers > CONFIG_HARDENED_USERCOPY_SPLIT_KMALLOC (future).) > > This series, which adds CONFIG_HARDENED_USERCOPY, checks that objects > being copied to/from userspace meet certain criteria: > - if address is a heap object, the size must not exceed the object's > allocated size. (This will catch all kinds of heap overflow flaws.) > - if address range is in the current process stack, it must be within the > current stack frame (if such checking is possible) or at least entirely > within the current process's stack. (This could catch large lengths that > would have extended beyond the current process stack, or overflows if > their length extends back into the original stack.) > - if the address range is part of kernel data, rodata, or bss, allow it. > - if address range is page-allocated, that it doesn't span multiple > allocations. > - if address is within the kernel text, reject it. > - everything else is accepted > > The patches in the series are: > - The core copy_to/from_user() checks, without the slab object checks: > 1- mm: Hardened usercopy > - Per-arch enablement of the protection: > 2- x86/uaccess: Enable hardened usercopy > 3- ARM: uaccess: Enable hardened usercopy > 4- arm64/uaccess: Enable hardened usercopy > 5- ia64/uaccess: Enable hardened usercopy > 6- powerpc/uaccess: Enable hardened usercopy > 7- sparc/uaccess: Enable hardened usercopy Was there a reason why you did not change s390? -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
