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Alexey Dobriyan b202ac9c73 proc: fix lookup in /proc/net subdirectories after setns(2)
[ Upstream commit c6c75deda8 ]

Commit 1fde6f21d9 ("proc: fix /proc/net/* after setns(2)") only forced
revalidation of regular files under /proc/net/

However, /proc/net/ is unusual in the sense of /proc/net/foo handlers
take netns pointer from parent directory which is old netns.

Steps to reproduce:

	(void)open("/proc/net/sctp/snmp", O_RDONLY);
	unshare(CLONE_NEWNET);

	int fd = open("/proc/net/sctp/snmp", O_RDONLY);
	read(fd, &c, 1);

Read will read wrong data from original netns.

Patch forces lookup on every directory under /proc/net .

Link: https://lkml.kernel.org/r/20201205160916.GA109739@localhost.localdomain
Fixes: 1da4d377f9 ("proc: revalidate misc dentries")
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reported-by: "Rantala, Tommi T. (Nokia - FI/Espoo)" <tommi.t.rantala@nokia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-12-30 11:53:56 +01:00
2020-12-11 14:02:14 -08:00
2020-12-11 14:02:14 -08:00
2020-12-30 11:53:54 +01:00
2020-12-26 16:02:46 +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.
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