[v2,0/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC

Message

Giuseppe Scrivano Oct. 19, 2020, 10:26 a.m. UTC

When the new flag is used, close_range will set the close-on-exec bit
for the file descriptors instead of close()-ing them.

It is useful for e.g. container runtimes that want to minimize the
number of syscalls used after a seccomp profile is installed but want
to keep some fds open until the container process is executed.

v1->v2:
* move close_range(..., CLOSE_RANGE_CLOEXEC) implementation to a separate function.
* use bitmap_set() to set the close-on-exec bits in the bitmap.
* add test with rlimit(RLIMIT_NOFILE) in place.
* use "cur_max" that is already used by close_range(..., 0).

Giuseppe Scrivano (2):
  fs, close_range: add flag CLOSE_RANGE_CLOEXEC
  selftests: add tests for CLOSE_RANGE_CLOEXEC

 fs/file.c                                     | 44 ++++++++---
 include/uapi/linux/close_range.h              |  3 +
 .../testing/selftests/core/close_range_test.c | 74 +++++++++++++++++++
 3 files changed, 111 insertions(+), 10 deletions(-)

--
2.26.2

Comments

Christian Brauner Oct. 29, 2020, 3:38 p.m. UTC | #1

On Mon, Oct 19, 2020 at 12:26:52PM +0200, Giuseppe Scrivano wrote:
> When the new flag is used, close_range will set the close-on-exec bit
> for the file descriptors instead of close()-ing them.
> 
> It is useful for e.g. container runtimes that want to minimize the
> number of syscalls used after a seccomp profile is installed but want
> to keep some fds open until the container process is executed.
> 
> v1->v2:
> * move close_range(..., CLOSE_RANGE_CLOEXEC) implementation to a separate function.
> * use bitmap_set() to set the close-on-exec bits in the bitmap.
> * add test with rlimit(RLIMIT_NOFILE) in place.
> * use "cur_max" that is already used by close_range(..., 0).

I'm picking this up for some testing, thanks
Christian

Giuseppe Scrivano Oct. 29, 2020, 4:47 p.m. UTC | #2

Hi Christian,

Christian Brauner <[e-mail]> writes:

> On Mon, Oct 19, 2020 at 12:26:52PM +0200, Giuseppe Scrivano wrote:
>> When the new flag is used, close_range will set the close-on-exec bit
>> for the file descriptors instead of close()-ing them.
>> 
>> It is useful for e.g. container runtimes that want to minimize the
>> number of syscalls used after a seccomp profile is installed but want
>> to keep some fds open until the container process is executed.
>> 
>> v1->v2:
>> * move close_range(..., CLOSE_RANGE_CLOEXEC) implementation to a separate function.
>> * use bitmap_set() to set the close-on-exec bits in the bitmap.
>> * add test with rlimit(RLIMIT_NOFILE) in place.
>> * use "cur_max" that is already used by close_range(..., 0).
>
> I'm picking this up for some testing, thanks
> Christian

thanks!  I've addressed the comments you had for v2 and pushed them
here[1] but I've not sent yet v3 as I was waiting for a feedback from Al
whether using bitmap_set() is fine.

Regards,
Giuseppe

[1] https://github.com/giuseppe/linux/tree/close-range-cloexec

Christian Brauner Nov. 18, 2020, 10:02 a.m. UTC | #3

On Thu, Oct 29, 2020 at 05:47:53PM +0100, Giuseppe Scrivano wrote:
> Hi Christian,
> 
> Christian Brauner <[e-mail]> writes:
> 
> > On Mon, Oct 19, 2020 at 12:26:52PM +0200, Giuseppe Scrivano wrote:
> >> When the new flag is used, close_range will set the close-on-exec bit
> >> for the file descriptors instead of close()-ing them.
> >> 
> >> It is useful for e.g. container runtimes that want to minimize the
> >> number of syscalls used after a seccomp profile is installed but want
> >> to keep some fds open until the container process is executed.
> >> 
> >> v1->v2:
> >> * move close_range(..., CLOSE_RANGE_CLOEXEC) implementation to a separate function.
> >> * use bitmap_set() to set the close-on-exec bits in the bitmap.
> >> * add test with rlimit(RLIMIT_NOFILE) in place.
> >> * use "cur_max" that is already used by close_range(..., 0).
> >
> > I'm picking this up for some testing, thanks
> > Christian
> 
> thanks!  I've addressed the comments you had for v2 and pushed them
> here[1] but I've not sent yet v3 as I was waiting for a feedback from Al
> whether using bitmap_set() is fine.

Send it please.
Christian