86def3dcd6
Treat it as a synonym for GRND_NONBLOCK. The reasoning is this: We have two choices for handling Linux's GRND_INSECURE API flag. 1. We could ignore it completely (like GRND_RANDOM). However, this might produce the surprising result of GRND_INSECURE requests blocking, when the Linux API does not block. 2. Alternatively, we could treat GRND_INSECURE requests as requests for GRND_NONBLOCk. Here, the surprising result for Linux programs is that invocations with unseeded random(4) will produce EAGAIN, rather than garbage. Honoring the flag in the way Linux does seems fraught. If we actually use the output of a random(4) implementation prior to seeding, we leak some entropy (in an information theory and also practical sense) from what will be the initial seed to attackers (or allow attackers to arbitrary DoS initial seeding, if we don't leak). This seems unacceptable -- it defeats the purpose of blocking on initial seeding. Secondary to that concern, before seeding we may have arbitrarily little entropy collected; producing output from zero or a handful of entropy bits does not seem particularly useful to userspace. If userspace can accept garbage, insecure, non-random bytes, they can create their own insecure garbage with srandom(time(NULL)) or similar. Any program which would be satisfied with a 3-bit key CTR stream has no need for CSPRNG bytes. So asking the kernel to produce such an output from the secure getrandom(2) API seems inane. For now, we've elected to emulate GRND_INSECURE as an alternative spelling of GRND_NONBLOCK (2). Consider this API not-quite stable for now. We guarantee it will never block. But we will attempt to monitor actual port uptake of this bizarre API and may revise our plans for the unseeded behavior (prior stable/13 branching). Approved by: csprng(markm), manpages(bcr) See also: https://lwn.net/ml/linux-kernel/cover.1577088521.git.luto@kernel.org/ See also: https://lwn.net/ml/linux-kernel/20200107204400.GH3619@mit.edu/ Differential Revision: https://reviews.freebsd.org/D23130 |
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|---|---|---|
| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| stand | ||
| sys | ||
| targets | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| .arcconfig | ||
| .arclint | ||
| .cirrus.yml | ||
| .clang-format | ||
| .gitattributes | ||
| .gitignore | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| Makefile.libcompat | ||
| Makefile.sys.inc | ||
| ObsoleteFiles.inc | ||
| README | ||
| README.md | ||
| RELNOTES | ||
| UPDATING | ||
FreeBSD Source:
This is the top level of the FreeBSD source directory. This file
was last revised on:
FreeBSD
FreeBSD is an operating system used to power modern servers, desktops, and embedded platforms. A large community has continually developed it for more than thirty years. Its advanced networking, security, and storage features have made FreeBSD the platform of choice for many of the busiest web sites and most pervasive embedded networking and storage devices.
For copyright information, please see the file COPYRIGHT in this directory. Additional copyright information also exists for some sources in this tree - please see the specific source directories for more information.
The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree. See build(7), config(8), https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html, and https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html for more information, including setting make(1) variables.
Source Roadmap:
bin System/user commands.
cddl Various commands and libraries under the Common Development
and Distribution License.
contrib Packages contributed by 3rd parties.
crypto Cryptography stuff (see crypto/README).
etc Template files for /etc.
gnu Various commands and libraries under the GNU Public License.
Please see gnu/COPYING* for more information.
include System include files.
kerberos5 Kerberos5 (Heimdal) package.
lib System libraries.
libexec System daemons.
release Release building Makefile & associated tools.
rescue Build system for statically linked /rescue utilities.
sbin System commands.
secure Cryptographic libraries and commands.
share Shared resources.
stand Boot loader sources.
sys Kernel sources.
sys/<arch>/conf Kernel configuration files. GENERIC is the configuration
used in release builds. NOTES contains documentation of
all possible entries.
tests Regression tests which can be run by Kyua. See tests/README
for additional information.
tools Utilities for regression testing and miscellaneous tasks.
usr.bin User commands.
usr.sbin System administration commands.
For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see:
https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/current-stable.html