Christian Brauner c46b05132a UPSTREAM: signal: use fdget() since we don't allow O_PATH
As stated in the original commit for pidfd_send_signal() we don't allow
to signal processes through O_PATH file descriptors since it is
semantically equivalent to a write on the pidfd.

We already correctly error out right now and return EBADF if an O_PATH
fd is passed.  This is because we use file->f_op to detect whether a
pidfd is passed and O_PATH fds have their file->f_op set to empty_fops
in do_dentry_open() and thus fail the test.

Thus, there is no regression.  It's just semantically correct to use
fdget() and return an error right from there instead of taking a
reference and returning an error later.

Signed-off-by: Christian Brauner <christian@brauner.io>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jann Horn <jann@thejh.net>
Cc: David Howells <dhowells@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

(cherry picked from commit 738a7832d2)

Bug: 135608568
Test: test program using syscall(__NR_pidfd_send_signal,..) to send SIGKILL
Change-Id: Ib102922f9793e8610940d34ad5fb1256d4b07476
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
2019-08-12 13:36:37 -04:00
2019-08-04 09:37:11 +02:00
2019-07-26 10:31:53 +02:00
2019-08-11 15:21:36 +02:00
2019-06-15 16:12:59 +02:00
2019-08-06 20:08:18 +02:00
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2019-08-06 20:08:18 +02:00
2019-08-11 15:21:36 +02:00
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2019-08-06 20:08:18 +02:00
2019-08-06 20:08:18 +02:00
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2019-08-11 15:21:36 +02:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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