lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-Id: <20211227205500.214777-1-flaniel@linux.microsoft.com>
Date:   Mon, 27 Dec 2021 21:54:58 +0100
From:   Francis Laniel <flaniel@...ux.microsoft.com>
To:     linux-kernel@...r.kernel.org
Cc:     Serge Hallyn <serge@...lyn.com>,
        linux-security-module@...r.kernel.org,
        Francis Laniel <flaniel@...ux.microsoft.com>
Subject: [RFC PATCH v1 0/2] Add capabilities file to sysfs

Hi.


First, I hope you are fine and the same for your relatives.

Capabilities are used to check if a thread has the right to perform a given
action [1].
For example, a thread with CAP_BPF set can use the bpf() syscall.

Capabilities are used in the container world.
In terms of code, several projects related to container maintain code where the
capabilities are written alike include/uapi/linux/capability.h [2][3][4][5].
For these projects, their codebase should be updated when a new capability is
added to the kernel.
Some other projects rely on <sys/capability.h> [6].
In this case, this header file should reflect the capabilities offered by the
kernel.

So, in this series, I added a new file to sysfs: /sys/kernel/capabilities.
The goal of this file is to be used by "container world" software to know kernel
capabilities at run time instead of compile time.

The underlying kernel attribute is read-only and its content is the capability
number associated with the capability name:
root@...amd64:~# cat /sys/kernel/capabilities
0       CAP_CHOWN
1       CAP_DAC_OVERRIDE
...
39      CAP_BPF

The kernel already exposes the last capability number under:
/proc/sys/kernel/cap_last_cap
So, I think there should not be any issue exposing all the capabilities it
offers.
If there is any, please share it as I do not want to introduce issue with this
series.

Also, if you see any way to improve this series please share it as it would
increase this contribution quality.

Francis Laniel (2):
  capability: Add cap_strings.
  kernel/ksysfs.c: Add capabilities attribute.

 include/uapi/linux/capability.h |  1 +
 kernel/capability.c             | 45 +++++++++++++++++++++++++++++++++
 kernel/ksysfs.c                 | 18 +++++++++++++
 3 files changed, 64 insertions(+)


Best regards and thank you in advance for your reviews.
---
[1] man capabilities
[2] https://github.com/containerd/containerd/blob/1a078e6893d07fec10a4940a5664fab21d6f7d1e/pkg/cap/cap_linux.go#L135
[3] https://github.com/moby/moby/commit/485cf38d48e7111b3d1f584d5e9eab46a902aabc#diff-2e04625b209932e74c617de96682ed72fbd1bb0d0cb9fb7c709cf47a86b6f9c1
moby relies on containerd code.
[4] https://github.com/syndtr/gocapability/blob/42c35b4376354fd554efc7ad35e0b7f94e3a0ffb/capability/enum.go#L47
[5] https://github.com/opencontainers/runc/blob/00f56786bb220b55b41748231880ba0e6380519a/libcontainer/capabilities/capabilities.go#L12
runc relies on syndtr package.
[6] https://github.com/containers/crun/blob/fafb556f09e6ffd4690c452ff51856b880c089f1/src/libcrun/linux.c#L35

-- 
2.30.2

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ