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[ Upstream commit 543841d1806029889c2f69f040e88b247aba8e22 ] Zbigniew mentioned at Linux Plumber's that systemd is interested in switching to execveat() for service execution, but can't, because the contents of /proc/pid/comm are the file descriptor which was used, instead of the path to the binary[1]. This makes the output of tools like top and ps useless, especially in a world where most fds are opened CLOEXEC so the number is truly meaningless. When the filename passed in is empty (e.g. with AT_EMPTY_PATH), use the dentry's filename for "comm" instead of using the useless numeral from the synthetic fdpath construction. This way the actual exec machinery is unchanged, but cosmetically the comm looks reasonable to admins investigating things. Instead of adding TASK_COMM_LEN more bytes to bprm, use one of the unused flag bits to indicate that we need to set "comm" from the dentry. Suggested-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> Suggested-by: Tycho Andersen <tandersen@netflix.com> Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Link: https://github.com/uapi-group/kernel-features#set-comm-field-before-exec [1] Reviewed-by: Aleksa Sarai <cyphar@cyphar.com> Tested-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> Signed-off-by: Kees Cook <kees@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.