Amir Goldstein ffe1766a3a fanotify: allow reporting errors on failure to open fd
[ Upstream commit 522249f05c5551aec9ec0ba9b6438f1ec19c138d ]

When working in "fd mode", fanotify_read() needs to open an fd
from a dentry to report event->fd to userspace.

Opening an fd from dentry can fail for several reasons.
For example, when tasks are gone and we try to open their
/proc files or we try to open a WRONLY file like in sysfs
or when trying to open a file that was deleted on the
remote network server.

Add a new flag FAN_REPORT_FD_ERROR for fanotify_init().
For a group with FAN_REPORT_FD_ERROR, we will send the
event with the error instead of the open fd, otherwise
userspace may not get the error at all.

For an overflow event, we report -EBADF to avoid confusing FAN_NOFD
with -EPERM.  Similarly for pidfd open errors we report either -ESRCH
or the open error instead of FAN_NOPIDFD and FAN_EPIDFD.

In any case, userspace will not know which file failed to
open, so add a debug print for further investigation.

Reported-by: Krishna Vivek Vitta <kvitta@microsoft.com>
Link: https://lore.kernel.org/linux-fsdevel/SI2P153MB07182F3424619EDDD1F393EED46D2@SI2P153MB0718.APCP153.PROD.OUTLOOK.COM/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20241003142922.111539-1-amir73il@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-12-14 20:00:05 +01:00
2024-12-14 19:59:57 +01:00
2024-12-14 20:00:03 +01:00
2022-09-28 09:02:20 +02:00
2024-12-11 16:13:43 +01:00

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.

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.
Description
No description provided
Readme 7.9 GiB
Languages
C 97.7%
Assembly 1.6%
Makefile 0.3%
Perl 0.1%