selftests/pidfd: expand common pidfd header

Move more infrastructure to the pidfd header.

Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-9-c8c3d8361705@kernel.org
Signed-

selftests/pidfd: expand common pidfd header

Move more infrastructure to the pidfd header.

Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-9-c8c3d8361705@kernel.org
Signed-off-by: Christian Brauner <[email protected]>

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selftests/pidfd: add tests for PIDFD_SELF_*

Add tests to assert that PIDFD_SELF* correctly refers to the current
thread and process.

We explicitly test pidfd_send_signal(), however We defer testing

selftests/pidfd: add tests for PIDFD_SELF_*

Add tests to assert that PIDFD_SELF* correctly refers to the current
thread and process.

We explicitly test pidfd_send_signal(), however We defer testing of
mm-specific functionality which uses pidfd, namely process_madvise() and
process_mrelease() to mm testing (though note the latter can not be
sensibly tested as it would require the testing process to be dying).

We also correct the pidfd_open_test.c fields which refer to .request_mask
whereas the UAPI header refers to .mask, which otherwise break the import
of the UAPI header.

Signed-off-by: Lorenzo Stoakes <[email protected]>
Link: https://lore.kernel.org/r/7ab0e48b26ba53abf7b703df2dd11a2e99b8efb2.1738268370.git.lorenzo.stoakes@oracle.com
Reviewed-by: Shakeel Butt <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

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pidfd: add ioctl to retrieve pid info

A common pattern when using pid fds is having to get information
about the process, which currently requires /proc being mounted,
resolving the fd to a pid, and

pidfd: add ioctl to retrieve pid info

A common pattern when using pid fds is having to get information
about the process, which currently requires /proc being mounted,
resolving the fd to a pid, and then do manual string parsing of
/proc/N/status and friends. This needs to be reimplemented over
and over in all userspace projects (e.g.: I have reimplemented
resolving in systemd, dbus, dbus-daemon, polkit so far), and
requires additional care in checking that the fd is still valid
after having parsed the data, to avoid races.

Having a programmatic API that can be used directly removes all
these requirements, including having /proc mounted.

As discussed at LPC24, add an ioctl with an extensible struct
so that more parameters can be added later if needed. Start with
returning pid/tgid/ppid and creds unconditionally, and cgroupid
optionally.

Signed-off-by: Luca Boccassi <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Christian Brauner <[email protected]>

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selftests: pidfd: ksft_exit functions do not return

After commit f7d5bcd35d42 ("selftests: kselftest: Mark functions that
unconditionally call exit() as __noreturn"), ksft_exit_...() functions
are m

selftests: pidfd: ksft_exit functions do not return

After commit f7d5bcd35d42 ("selftests: kselftest: Mark functions that
unconditionally call exit() as __noreturn"), ksft_exit_...() functions
are marked as __noreturn, which means the return type should not be
'int' but 'void' because they are not returning anything (and never were
since exit() has always been called).

To facilitate updating the return type of these functions, remove
'return' before the calls to ksft_exit_{pass,fail}(), as __noreturn
prevents the compiler from warning that a caller of the ksft_exit
functions does not return a value because the program will terminate
upon calling these functions.

Just removing 'return' would have resulted in

!ret ? ksft_exit_pass() : ksft_exit_fail();

so convert that into the more idiomatic

if (ret)
ksft_exit_fail();
ksft_exit_pass();

Reviewed-by: Muhammad Usama Anjum <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests: pidfd: fix compilation errors due to wait.h

Drop unneeded <linux/wait.h> header inclusion to fix pidfd compilation
errors seen in Fedora 32:

In file included from pidfd_open_test.c:9:
..

selftests: pidfd: fix compilation errors due to wait.h

Drop unneeded <linux/wait.h> header inclusion to fix pidfd compilation
errors seen in Fedora 32:

In file included from pidfd_open_test.c:9:
../../../../usr/include/linux/wait.h:17:16: error: expected identifier before numeric constant
17 | #define P_ALL 0
| ^

Signed-off-by: Tommi Rantala <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Acked-by: Christian Brauner <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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tests: move common definitions and functions into pidfd.h

Move definitions and functions used across different pidfd tests into
pidfd.h header.

Signed-off-by: Suren Baghdasaryan <[email protected]>

tests: move common definitions and functions into pidfd.h

Move definitions and functions used across different pidfd tests into
pidfd.h header.

Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Christian Brauner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Christian Brauner <[email protected]>

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tests: add pidfd_open() tests

This adds testing for the new pidfd_open() syscalls. Specifically, we test:
- that no invalid flags can be passed to pidfd_open()
- that no invalid pid can be passed to

tests: add pidfd_open() tests

This adds testing for the new pidfd_open() syscalls. Specifically, we test:
- that no invalid flags can be passed to pidfd_open()
- that no invalid pid can be passed to pidfd_open()
- that a pidfd can be retrieved with pidfd_open()
- that the retrieved pidfd references the correct pid

Signed-off-by: Christian Brauner <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: David Howells <[email protected]>
Cc: "Michael Kerrisk (man-pages)" <[email protected]>
Cc: Andy Lutomirsky <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Aleksa Sarai <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Al Viro <[email protected]>
Cc: [email protected]

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