https://fedoraproject.org/wiki/Changes/Add_FORTIFY_SOURCE%3D3_to_distribution_build_flags
This document represents a proposed Change. As part of the Changes process, proposals are publicly announced in order to receive community feedback. This proposal will only be implemented if approved by the Fedora Engineering Steering Committee. == Summary == Replace the current `_FORTIFY_SOURCE=2` with `_FORTIFY_SOURCE=3` to improve mitigation of security issues arising from buffer overflows in packages in Fedora. == Owner == * Name: [[User:siddhesh| Siddhesh Poyarekar]] * Email: sipoy...@redhat.com == Detailed Description == Default C and C++ compiler flags to build packages in Fedora currently includes `-Wp,-D_FORTIFY_SOURCE=2`, which enables fortification of some functions in glibc, thus providing some mitigation against buffer overflows. Since glibc 2.34 and GCC 12, there has been a new fortification level (`_FORTIFY_SOURCE=3`) which improves the coverage of this mitigation. The core change to bring in this mitigation is to change the default build flags in `redhat-rpm-config` so that packages build by default with `-Wp,-D_FORTIFY_SOURCE=3`. There are packages (e.g. `systemd`) that do not interact well with `_FORTIFY_SOURCE` and will also need a workaround to downgrade fortification to level 2. The change will also include this override. == Benefit to Fedora == [https://docs.google.com/spreadsheets/d/1nPSmbEf3HVB91zI8yBraMqVry3_ILmlV2Z5K7FZeHZg/edit?usp=sharing Analysis of packages] in Fedora rawhide indicate that the improvement of mitigation coverage is on average over 2.4x, in some cases protecting more than half of the fortified glibc calls in the target application. This change will thus harden Fedora to a significant extent, thus making it a more secure distribution out of the box. == Scope == * Proposal owners: Post a merge request to redhat-rpm-config with the actual change to build flags. * Other developers: Resolve bugs filed for build failures, either by fixing the bug exposed by `_FORTIFY_SOURCE=3` or by disabling `_FORTIFY_SOURCE=3` for the package if it is a false positive or if the package is unable to adapt to the change. * Release engineering: Mass rebuild required * Policies and guidelines: Guidelines should include workaround for packages that fail to build with `-Wp,-D_FORTIFY_SOURCE=3` due to a false positive. * Trademark approval: N/A (not needed for this Change) == Upgrade/compatibility impact == No ABI change, so there should be no impact on compatibility in a mixed environment. == How To Test == * Smoke testing of packages to ensure that they continue to work correctly. Some packages may have overflows exposed at runtime, which may need to be fixed. == User Experience == No noticeable change to users. == Dependencies == None. == Contingency Plan == * Contingency mechanism: (What to do? Who will do it?) If too many packages are found to be broken at runtime, the default for fortification will be left at `_FORTIFY_SOURCE=2` for Fedora 38. Change owner will do this in `redhat-rpm-config` * Contingency deadline: Beta freeze * Blocks release? Yes * Blocks product? No == Documentation == [https://developers.redhat.com/articles/2022/09/17/gccs-new-fortification-level# More context on `_FORTIFY_SOURCE=3` improvements]. == Release Notes == -- Ben Cotton He / Him / His Fedora Program Manager Red Hat TZ=America/Indiana/Indianapolis _______________________________________________ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue
