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Merge tag 'vfs-6.12.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull procfs updates from Christian Brauner:
"This contains the following changes for procfs:
- Add config options and parameters to block forcing memory writes.
This adds a Kconfig option and boot param to allow removing the
FOLL_FORCE flag from /proc/<pid>/mem write calls as this can be
used in various attacks.
The traditional forcing behavior is kept as default because it can
break GDB and some other use cases.
This is the simpler version that you had requested.
- Restrict overmounting of ephemeral entities.
It is currently possible to mount on top of various ephemeral
entities in procfs. This specifically includes magic links. To
recap, magic links are links of the form /proc/<pid>/fd/<nr>. They
serve as references to a target file and during path lookup they
cause a jump to the target path. Such magic links disappear if the
corresponding file descriptor is closed.
Currently it is possible to overmount such magic links. This is
mostly interesting for an attacker that wants to somehow trick a
process into e.g., reopening something that it didn't intend to
reopen or to hide a malicious file descriptor.
But also it risks leaking mounts for long-running processes. When
overmounting a magic link like above, the mount will not be
detached when the file descriptor is closed. Only the target
mountpoint will disappear. Which has the consequence of making it
impossible to unmount that mount afterwards. So the mount will
stick around until the process exits and the /proc/<pid>/ directory
is cleaned up during proc_flush_pid() when the dentries are pruned
and invalidated.
That in turn means it's possible for a program to accidentally leak
mounts and it's also possible to make a task leak mounts without
it's knowledge if the attacker just keeps overmounting things under
/proc/<pid>/fd/<nr>.
Disallow overmounting of such ephemeral entities.
- Cleanup the readdir method naming in some procfs file operations.
- Replace kmalloc() and strcpy() with a simple kmemdup() call"
* tag 'vfs-6.12.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
proc: fold kmalloc() + strcpy() into kmemdup()
proc: block mounting on top of /proc/<pid>/fdinfo/*
proc: block mounting on top of /proc/<pid>/fd/*
proc: block mounting on top of /proc/<pid>/map_files/*
proc: add proc_splice_unmountable()
proc: proc_readfdinfo() -> proc_fdinfo_iterate()
proc: proc_readfd() -> proc_fd_iterate()
proc: add config & param to block forcing mem writes
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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 reStructuredText 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.