On Tue, Oct 01, 2019 at 11:10:51AM +1000, Aleksa Sarai wrote: > Patch changelog: > v4: > * __always_inline copy_struct_from_user(). [Kees Cook] > * Rework test_user_copy.ko changes. [Kees Cook] > v3: <https://lore.kernel.org/lkml/20190930182810.6090-1-cyphar@xxxxxxxxxx/> > <https://lore.kernel.org/lkml/20190930191526.19544-1-asarai@xxxxxxx/> > v2: <https://lore.kernel.org/lkml/20190925230332.18690-1-cyphar@xxxxxxxxxx/> > v1: <https://lore.kernel.org/lkml/20190925165915.8135-1-cyphar@xxxxxxxxxx/> > > This series was split off from the openat2(2) syscall discussion[1]. > However, the copy_struct_to_user() helper has been dropped, because > after some discussion it appears that there is no really obvious > semantics for how copy_struct_to_user() should work on mixed-vintages > (for instance, whether [2] is the correct semantics for all syscalls). > > A common pattern for syscall extensions is increasing the size of a > struct passed from userspace, such that the zero-value of the new fields > result in the old kernel behaviour (allowing for a mix of userspace and > kernel vintages to operate on one another in most cases). > > Previously there was no common lib/ function that implemented > the necessary extension-checking semantics (and different syscalls > implemented them slightly differently or incompletely[3]). This series > implements the helper and ports several syscalls to use it. > > Some in-kernel selftests are included in this patch. More complete > self-tests for copy_struct_from_user() are included in the openat2() > patchset. > > [1]: https://lore.kernel.org/lkml/20190904201933.10736-1-cyphar@xxxxxxxxxx/ > > [2]: commit 1251201c0d34 ("sched/core: Fix uclamp ABI bug, clean up and > robustify sched_read_attr() ABI logic and code") > > [3]: For instance {sched_setattr,perf_event_open,clone3}(2) all do do > similar checks to copy_struct_from_user() while rt_sigprocmask(2) > always rejects differently-sized struct arguments. > > Aleksa Sarai (4): > lib: introduce copy_struct_from_user() helper > clone3: switch to copy_struct_from_user() > sched_setattr: switch to copy_struct_from_user() > perf_event_open: switch to copy_struct_from_user() > > include/linux/bitops.h | 7 ++ > include/linux/uaccess.h | 70 +++++++++++++++++++ > include/uapi/linux/sched.h | 2 + > kernel/events/core.c | 47 +++---------- > kernel/fork.c | 34 ++-------- > kernel/sched/core.c | 43 ++---------- > lib/strnlen_user.c | 8 +-- > lib/test_user_copy.c | 136 +++++++++++++++++++++++++++++++++++-- > lib/usercopy.c | 55 +++++++++++++++ > 9 files changed, 288 insertions(+), 114 deletions(-) I've picked this up now and it's sitting in https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/log/?h=copy_struct_from_user It should show up in linux-next tomorrow. I will let this sit there for a few days but overall this seems good to have in rc2. If someone objects and prefers to take it through their tree I can drop it. Christian
