Switch away from using sha1 for module signing by default and use the more modern sha512 instead, which is what among others Arch, Fedora, RHEL, and Ubuntu are currently using for their kernels. Sha1 has not been considered secure against well-funded opponents since 2005[1]; since 2011 the NIST and other organizations furthermore recommended its replacement[2]. This is why OpenSSL on RHEL9, Fedora Linux 41+[3], and likely some other current and future distributions reject the creation of sha1 signatures, which leads to a build error of allmodconfig configurations: 80A20474797F0000:error:03000098:digital envelope routines:do_sigver_init:invalid digest:crypto/evp/m_sigver.c:342: make[4]: *** [.../certs/Makefile:53: certs/signing_key.pem] Error 1 make[4]: *** Deleting file 'certs/signing_key.pem' make[4]: *** Waiting for unfinished jobs.... make[3]: *** [.../scripts/Makefile.build:478: certs] Error 2 make[2]: *** [.../Makefile:1936: .] Error 2 make[1]: *** [.../Makefile:224: __sub-make] Error 2 make[1]: Leaving directory '...' make: *** [Makefile:224: __sub-make] Error 2 This change makes allmodconfig work again and sets a default that is more appropriate for current and future users, too. Link: https://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html [1] Link: https://csrc.nist.gov/projects/hash-functions [2] Link: https://fedoraproject.org/wiki/Changes/OpenSSLDistrustsha1SigVer [3] Signed-off-by: Thorsten Leemhuis <linux@xxxxxxxxxxxxx> --- v2: * use 'default MODULE_SIG_SHA512' in the "Hash algorithm to sign modules" choice instead of resorting the entries there. * rewrite patch description * drop RFC tag v1: https://lore.kernel.org/all/42aa307d7ffae1851b4a8787f5c276dd0b3beece.1728543368.git.linux@xxxxxxxxxxxxx/ --- kernel/module/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig index 7c6588148d42d3..0c746a150e34e2 100644 --- a/kernel/module/Kconfig +++ b/kernel/module/Kconfig @@ -231,6 +231,7 @@ comment "Do not forget to sign required modules with scripts/sign-file" choice prompt "Hash algorithm to sign modules" depends on MODULE_SIG || IMA_APPRAISE_MODSIG + default MODULE_SIG_SHA512 help This determines which sort of hashing algorithm will be used during signature generation. This algorithm _must_ be built into the kernel base-commit: d3d1556696c1a993eec54ac585fe5bf677e07474 -- 2.45.0
