Pawan Gupta 8a03e56b25 bpf: Disallow unprivileged bpf by default
Disabling unprivileged BPF would help prevent unprivileged users from
creating certain conditions required for potential speculative execution
side-channel attacks on unmitigated affected hardware.

A deep dive on such attacks and current mitigations is available here [0].

Sync with what many distros are currently applying already, and disable
unprivileged BPF by default. An admin can enable this at runtime, if
necessary, as described in 08389d8882 ("bpf: Add kconfig knob for
disabling unpriv bpf by default").

  [0] "BPF and Spectre: Mitigating transient execution attacks", Daniel Borkmann, eBPF Summit '21
      https://ebpf.io/summit-2021-slides/eBPF_Summit_2021-Keynote-Daniel_Borkmann-BPF_and_Spectre.pdf

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/bpf/0ace9ce3f97656d5f62d11093ad7ee81190c3c25.1635535215.git.pawan.kumar.gupta@linux.intel.com
2021-11-01 17:06:47 +01:00
2021-10-28 01:02:44 +02:00
2021-09-23 11:01:12 -04:00
2021-10-06 12:28:30 -07:00
2021-09-26 14:08:19 -07:00

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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