FreeBSD src
85b7c566f1
Pointer authentication allows userspace to add instructions to insert a Pointer Authentication Code (PAC) into a register based on an address and modifier and check if the PAC is correct. If the check fails it will either return an invalid address or fault to the kernel. As many of these instructions are a NOP when disabled and in earlier revisions of the architecture this can be used, for example, to sign the return address before pushing it to the stack making Return-oriented programming (ROP) attack more difficult on hardware that supports them. The kernel manages five 128 bit signing keys: 2 instruction keys, 2 data keys, and a generic key. The instructions then use one of these when signing the registers. Instructions that use the first four store the PAC in the register being signed, however the instructions that use the generic key store the PAC in a separate register. Currently all userspace threads share all the keys within a process with a new set of userspace keys being generated when executing a new process. This means a forked child will share its keys with its parent until it calls an appropriate exec system call. In the kernel we allow the use of one of the instruction keys, the ia key. This will be used to sign return addresses in function calls. Unlike userspace each kernel thread has its own randomly generated. Thread0 has a static key as does the early code on secondary CPUs. This should be safe as there is minimal user interaction with these threads, however we could generate random keys when the Armv8.5 Random number generation instructions are present. Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D31261 |
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| .cirrus-ci | ||
| .github | ||
| 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.md | ||
| RELNOTES | ||
| UPDATING | ||
FreeBSD Source:
This is the top level of the FreeBSD source directory.
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), FreeBSD handbook on building userland, and Handbook for kernels for more information, including setting make(1) variables.
Source Roadmap:
| Directory | Description |
|---|---|
| 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 | Commands and libraries under the GNU General Public License (GPL) or Lesser General Public License (LGPL). Please see gnu/COPYING and gnu/COPYING.LIB 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 FreeBSD Handbook.