Messages in this thread | | | From | Yann Droneaud <> | Subject | [PATCH v3 0/8] Getting rid of get_unused_fd() / use O_CLOEXEC | Date | Fri, 6 Sep 2013 12:39:50 +0200 |
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Hi,
With help from subsystem maintainers, I've managed to get some of get_unused_fd() calls converted to use get_unused_fd_flags(O_CLOEXEC) instead. [ANDROID][IB][VFIO]
KVM subsystem maintainers helped me to change calls to anon_inode_getfd() to use O_CLOEXEC by default. [KVM]
Some maintainers applied my patches to convert get_unused_fd() to get_unused_fd_flags(0) were using O_CLOEXEC wasn't possible without breaking ABI. [SCTP][XFS]
So, still in the hope to get rid of get_unused_fd(), please find a another attempt to remove get_unused_fd() macro and encourage subsystems to use get_unused_fd_flags(O_CLOEXEC) or anon_inode_getfd(O_CLOEXEC) by default were appropriate.
The patchset convert all calls to get_unused_fd() to get_unused_fd_flags(0) before removing get_unused_fd() macro.
Without get_unused_fd() macro, more subsystems are likely to use anon_inode_getfd() and be teached to provide an API that let userspace choose the opening flags of the file descriptor.
Additionally I'm suggesting Industrial IO (IIO) subsystem to use anon_inode_getfd(O_CLOEXEC): it's the only subsystem using anon_inode_getfd() with a fixed set of flags not including O_CLOEXEC.
Not using O_CLOEXEC by default or not letting userspace provide the "open" flags should be considered bad practice from security point of view: in most case O_CLOEXEC must be used to not leak file descriptor across exec(). Using O_CLOEXEC by default when flags are not provided by userspace allows it to choose, without race, if the file descriptor is going to be inherited across exec().
Status:
In linux-next tag 20130906, they're currently:
- 22 calls to get_unused_fd_flags() (+3) not counting get_unused_fd() and anon_inode_getfd() - 7 calls to get_unused_fd() (-3) - 11 calls to anon_inode_getfd() (0)
Changes from patchset v2 [PATCHSETv2]:
- android/sw_sync: use get_unused_fd_flags(O_CLOEXEC) instead of get_unused_fd() DROPPED: applied upstream
- android/sync: use get_unused_fd_flags(O_CLOEXEC) instead of get_unused_fd() DROPPED: applied upstream
- vfio: use get_unused_fd_flags(0) instead of get_unused_fd() DROPPED: applied upstream. Additionally subsystem maintainer applied another patch on top to set the flags to O_CLOEXEC.
- industrialio: use anon_inode_getfd() with O_CLOEXEC flag NEW: propose to use O_CLOEXEC as default flag.
Links:
[ANDROID] http://lkml.kernel.org/r/CACSP8SjXGMk2_kX_+RgzqqQwqKernvF1Wt3K5tw991W5dfAnCA@mail.gmail.com http://lkml.kernel.org/r/CACSP8SjZcpcpEtQHzcGYhf-MP7QGo0XpN7-uN7rmD=vNtopG=w@mail.gmail.com
[IB] http://lkml.kernel.org/r/CAL1RGDXV1_BjSLrQDFdVQ1_D75+bMtOtikHOUp8VBiy_OJUf=w@mail.gmail.com
[VFIO] http://lkml.kernel.org/r/20130822171744.1297.13711.stgit@bling.home
[KVM] http://lkml.kernel.org/r/5219A8FC.8090307@redhat.com http://lkml.kernel.org/r/3557EF65-4327-4DAE-999A-B0EE13C433F5@suse.de http://lkml.kernel.org/r/20130826102023.GA8218@redhat.com
[SCTP] http://lkml.kernel.org/r/51D312E8.6090702@gmail.com http://lkml.kernel.org/r/20130702.161428.1703028286206350504.davem@davemloft.net
[XFS] http://lkml.kernel.org/r/20130709205321.GV20932@sgi.com
[PATCHSETv2] http://lkml.kernel.org/r/cover.1376327678.git.ydroneaud@opteya.com
Yann Droneaud (8): ia64: use get_unused_fd_flags(0) instead of get_unused_fd() ppc/cell: use get_unused_fd_flags(0) instead of get_unused_fd() binfmt_misc: use get_unused_fd_flags(0) instead of get_unused_fd() file: use get_unused_fd_flags(0) instead of get_unused_fd() fanotify: use get_unused_fd_flags(0) instead of get_unused_fd() events: use get_unused_fd_flags(0) instead of get_unused_fd() file: remove get_unused_fd() industrialio: use anon_inode_getfd() with O_CLOEXEC flag
arch/ia64/kernel/perfmon.c | 2 +- arch/powerpc/platforms/cell/spufs/inode.c | 4 ++-- drivers/iio/industrialio-event.c | 2 +- fs/binfmt_misc.c | 2 +- fs/file.c | 2 +- fs/notify/fanotify/fanotify_user.c | 2 +- include/linux/file.h | 1 - kernel/events/core.c | 2 +- 8 files changed, 8 insertions(+), 9 deletions(-)
-- 1.8.3.1
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