;; Contents extracted from Kicksecure's resources. (define-module (rosenthal utils kicksecure) #:export (%kicksecure-kernel-arguments %kicksecure-sysctl-rules)) ;; Source: ;; Extracted with the following command: ;; cat etc/default/grub.d/* | sed -e 's/#\+/;;/g' -e 's/GRUB.*DEFAULT /\"/g' -e 's/GRUB.*LINUX /\"/g' -e '/GRUB/d' -e 's/\(\".*[a-z0-9]\)\ \([a-z].*\"\)/\1\"\n\"\2/g' -e '/dpkg/d' (define %kicksecure-kernel-arguments '(;; Copyright (C) 2022 - 2022 ENCRYPTED SUPPORT LP ;; See the file COPYING for copying conditions. ;; Wiping RAM at shutdown to defeat cold boot attacks. ;; ;; RAM wipe is enabled by default on host operating systems, real hardware. ;; RAM wipe is disabled by in virtual machines (VMs). ;; ;; Most users should not make any modifications to this config file because ;; there is no need for that. ;; ;; User documentation: ;; https://www.kicksecure.com/wiki/Cold_Boot_Attack_Defense ;; ;; Design documentation: ;; https://www.kicksecure.com/wiki/Dev/RAM_Wipe ;; RAM wipe is omitted in virtual machines (VMs) by default because it is ;; unclear if that could actually lead to the host operating system using ;; swap. Through use of kernel parameter wiperam=force it is possible to ;; force RAM wipe inside VMs which is useful for testing, development purposes. ;; There is no additional security benefit by the wiperam=force setting ;; for host operating systems. ;;"wiperam=force" ;; Kernel parameter wiperam=skip is provided to support disabling RAM wipe ;; at shutdown, which might be useful to speed up shutdown or in case should ;; there ever be issues. ;;"wiperam=skip" ;; Copyright (C) 2019 - 2022 ENCRYPTED SUPPORT LP ;; See the file COPYING for copying conditions. ;; Enables all known mitigations for CPU vulnerabilities. ;; ;; https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/index.html ;; https://forums.whonix.org/t/should-all-kernel-patches-for-cpu-bugs-be-unconditionally-enabled-vs-performance-vs-applicability/7647 ;; Enable mitigations for Spectre variant 2 (indirect branch speculation). ;; ;; https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/spectre.html "spectre_v2=on" ;; Disable Speculative Store Bypass. "spec_store_bypass_disable=on" ;; Enable mitigations for the L1TF vulnerability through disabling SMT ;; and L1D flush runtime control. ;; ;; https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html "l1tf=full,force" ;; Enable mitigations for the MDS vulnerability through clearing buffer cache ;; and disabling SMT. ;; ;; https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html "mds=full,nosmt" ;; Patches the TAA vulnerability by disabling TSX and enables mitigations using ;; TSX Async Abort along with disabling SMT. ;; ;; https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html "tsx=off" "tsx_async_abort=full,nosmt" ;; Mark all huge pages in the EPT as non-executable to mitigate iTLB multihit. ;; ;; https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/multihit.html "kvm.nx_huge_pages=force" ;; Enables mitigations for SRBDS to prevent MDS attacks on RDRAND and RDSEED instructions. ;; Only mitigated through microcode updates from Intel. ;; ;; https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/special-register-buffer-data-sampling.html ;; https://access.redhat.com/solutions/5142691 ;; Force disable SMT as it has caused numerous CPU vulnerabilities. ;; The only full mitigation of cross-HT attacks is to disable SMT. ;; ;; https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/core-scheduling.html ;; https://forums.whonix.org/t/should-all-kernel-patches-for-cpu-bugs-be-unconditionally-enabled-vs-performance-vs-applicability/7647/17 "nosmt=force" ;; Enables the prctl interface to prevent leaks from L1D on context switches. ;; ;; https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1d_flush.html "l1d_flush=on" ;; Mitigates numerous MMIO Stale Data vulnerabilities and disables SMT. ;; ;; https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.html "mmio_stale_data=full,nosmt" ;; Copyright (C) 2019 - 2022 ENCRYPTED SUPPORT LP ;; See the file COPYING for copying conditions. ;; Distrusts the bootloader for initial entropy at boot. ;; ;; https://lkml.org/lkml/2022/6/5/271 "random.trust_bootloader=off" ;; Copyright (C) 2019 - 2022 ENCRYPTED SUPPORT LP ;; See the file COPYING for copying conditions. ;; Distrusts the CPU for initial entropy at boot as it is not possible to ;; audit, may contain weaknesses or a backdoor. ;; ;; https://en.wikipedia.org/wiki/RDRAND;;Reception ;; https://twitter.com/pid_eins/status/1149649806056280069 ;; https://archive.nytimes.com/www.nytimes.com/interactive/2013/09/05/us/documents-reveal-nsa-campaign-against-encryption.html ;; https://forums.whonix.org/t/entropy-config-random-trust-cpu-yes-or-no-rng-core-default-quality/8566 ;; https://lkml.org/lkml/2022/6/5/271 "random.trust_cpu=off" ;; Copyright (C) 2019 - 2022 ENCRYPTED SUPPORT LP ;; See the file COPYING for copying conditions. ;; Enables IOMMU to prevent DMA attacks. "intel_iommu=on" "amd_iommu=on" ;; Disable the busmaster bit on all PCI bridges during very ;; early boot to avoid holes in IOMMU. ;; ;; https://mjg59.dreamwidth.org/54433.html ;; https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4444f8541dad16fefd9b8807ad1451e806ef1d94 "efi=disable_early_pci_dma" ;; Enables strict enforcement of IOMMU TLB invalidation so devices will never be able to access stale data contents ;; https://github.com/torvalds/linux/blob/master/drivers/iommu/Kconfig;;L97 ;; Page 11 of https://lenovopress.lenovo.com/lp1467.pdf "iommu.passthrough=0" "iommu.strict=1" ;; Copyright (C) 2019 - 2022 ENCRYPTED SUPPORT LP ;; See the file COPYING for copying conditions. ;;echo ";; kver: $kver" ;; Disables the merging of slabs of similar sizes. ;; Sometimes a slab can be used in a vulnerable way which an attacker can exploit. "slab_nomerge" ;; Enables sanity checks (F) and redzoning (Z). ;; Disabled due to kernel deciding to implicitly disable kernel pointer hashing ;; https://github.com/torvalds/linux/commit/792702911f581f7793962fbeb99d5c3a1b28f4c3 ;;"slub_debug=FZ" ;; Zero memory at allocation and free time. "init_on_alloc=1" "init_on_free=1" ;; Machine check exception handler decides whether the system should panic or not based on the exception that happened. ;; https://forums.whonix.org/t/kernel-hardening/7296/494 ;;"mce=0" ;; Enables Kernel Page Table Isolation which mitigates Meltdown and improves KASLR. "pti=on" ;; Vsyscalls are obsolete, are at fixed addresses and are a target for ROP. "vsyscall=none" ;; Enables page allocator freelist randomization. "page_alloc.shuffle=1" ;; Enables randomisation of the kernel stack offset on syscall entries (introduced in kernel 5.13). ;; https://lkml.org/lkml/2019/3/18/246 "randomize_kstack_offset=on" ;; Enables kernel lockdown. ;; ;; Disabled for now as it enforces module signature verification which breaks ;; too many things. ;; https://forums.whonix.org/t/enforce-kernel-module-software-signature-verification-module-signing-disallow-kernel-module-loading-by-default/7880 ;; ;; "lockdown=confidentiality" ;;fi ;; Gather more entropy during boot. ;; ;; Requires linux-hardened kernel patch. ;; https://github.com/anthraxx/linux-hardened "extra_latent_entropy" ;; Restrict access to debugfs since it can contain a lot of sensitive information. ;; https://lkml.org/lkml/2020/7/16/122 ;; https://github.com/torvalds/linux/blob/fb1201aececc59990b75ef59fca93ae4aa1e1444/Documentation/admin-guide/kernel-parameters.txt;;L835-L848 "debugfs=off" ;; Force the kernel to panic on "oopses" (which may be due to false positives) ;; https://forums.whonix.org/t/set-oops-panic-kernel-parameter-or-kernel-panic-on-oops-1-sysctl-for-better-security/7713 ;; Implemented differently: ;; /usr/libexec/security-misc/panic-on-oops ;; /etc/X11/Xsession.d/50panic_on_oops ;; /etc/sudoers.d/security-misc ;;"oops=panic" ;; Copyright (C) 2019 - 2022 ENCRYPTED SUPPORT LP ;; See the file COPYING for copying conditions. ;; Prevent kernel info leaks in console during boot. ;; https://phabricator.whonix.org/T950 ;; LANG=C str_replace is provided by package helper-scripts. ;; The following command actually removed "quiet" from the kernel command line. ;; If verbosity is desired, the user might want to keep this line. ;; Remove "quiet" from "because "quiet" must be first. ;; If verbosity is desired, the user might want to out-comment the following line. "quiet" "loglevel=0" ;; NOTE: ;; After editing this file, running: ;; sudo update-grub ;; is required. ;; ;; If higher verbosity is desired, the user might also want to delete file ;; /etc/sysctl.d/30_silent-kernel-printk.conf ;; (or out-comment its settings). ;; ;; Alternatively, the user could consider to install the debug-misc package, ;; which will undo the settings found here. )) ;; Source > ;; Extracted with the following command: ;; cat etc/sysctl.d/* | sed -e 's/#\+/;;/g' -e 's/ = /=/g' -e 's/;;\(.*\..*\)=\(.*\)/;; ("\1" . "\2")/g' -e 's/\(.*\..*\)=\(.*\)/("\1" . "\2")/g' -e 's@/bin\|/usr/bin@/run/current-system/profile/bin@g' (define %kicksecure-sysctl-rules '(;; Copyright (C) 2019 - 2022 ENCRYPTED SUPPORT LP ;; See the file COPYING for copying conditions. ;; Disables coredumps. This setting may be overwritten by systemd so this may not be useful. ;; security-misc also disables coredumps in other ways. ("kernel.core_pattern" . "|/run/current-system/profile/bin/false") ;; Restricts the kernel log to root only. ("kernel.dmesg_restrict" . "1") ;; Don't allow writes to files that we don't own ;; in world writable sticky directories, unless ;; they are owned by the owner of the directory. ("fs.protected_fifos" . "2") ("fs.protected_regular" . "2") ;; Only allow symlinks to be followed when outside of ;; a world-writable sticky directory, or when the owner ;; of the symlink and follower match, or when the directory ;; owner matches the symlink's owner. ;; ;; Prevent hardlinks from being created by users that do not ;; have read/write access to the source file. ;; ;; These prevent many TOCTOU races. ("fs.protected_symlinks" . "1") ("fs.protected_hardlinks" . "1") ;; Hardens the BPF JIT compiler and restricts it to root. ("kernel.unprivileged_bpf_disabled" . "1") ("net.core.bpf_jit_harden" . "2") ;; Quote https://www.kernel.org/doc/html/latest/admin-guide/sysctl/kernel.html ;; ;; kexec_load_disabled: ;; ;; A toggle indicating if the kexec_load syscall has been disabled. This value defaults to 0 (false: kexec_load enabled), but can be set to 1 (true: kexec_load disabled). Once true, kexec can no longer be used, and the toggle cannot be set back to false. This allows a kexec image to be loaded before disabling the syscall, allowing a system to set up (and later use) an image without it being altered. Generally used together with the "modules_disabled" sysctl. ;; Disables kexec which can be used to replace the running kernel. ("kernel.kexec_load_disabled" . "1") ;; Hides kernel addresses in various files in /proc. ;; Kernel addresses can be very useful in certain exploits. ;; ;; https://kernsec.org/wiki/index.php/Bug_Classes/Kernel_pointer_leak ("kernel.kptr_restrict" . "2") ;; Improves ASLR effectiveness for mmap. ("vm.mmap_rnd_bits" . "32") ("vm.mmap_rnd_compat_bits" . "16") ;; Restricts the use of ptrace to root. This might break some programs running under WINE. ;; A workaround for WINE would be to give the wineserver and wine-preloader ptrace capabilities. This can be done by running: ;; ;; sudo apt-get install libcap2-bin ;; sudo setcap cap_sys_ptrace=eip /run/current-system/profile/bin/wineserver ;; sudo setcap cap_sys_ptrace=eip /run/current-system/profile/bin/wine-preloader ("kernel.yama.ptrace_scope" . "2") ;; Prevent setuid processes from creating coredumps. ("fs.suid_dumpable" . "0") ;; Randomize the addresses for mmap base, heap, stack, and VDSO pages ("kernel.randomize_va_space" . "2") ;; meta start ;; project Kicksecure ;; category networking and security ;; description ;; TCP/IP stack hardening ;; Protects against time-wait assassination. ;; It drops RST packets for sockets in the time-wait state. ("net.ipv4.tcp_rfc1337" . "1") ;; Disables ICMP redirect acceptance. ("net.ipv4.conf.all.accept_redirects" . "0") ("net.ipv4.conf.default.accept_redirects" . "0") ("net.ipv4.conf.all.secure_redirects" . "0") ("net.ipv4.conf.default.secure_redirects" . "0") ("net.ipv6.conf.all.accept_redirects" . "0") ("net.ipv6.conf.default.accept_redirects" . "0") ;; Disables ICMP redirect sending. ("net.ipv4.conf.all.send_redirects" . "0") ("net.ipv4.conf.default.send_redirects" . "0") ;; Ignores ICMP requests. ("net.ipv4.icmp_echo_ignore_all" . "1") ("net.ipv6.icmp.echo_ignore_all" . "1") ;; Ignores bogus ICMP error responses ("net.ipv4.icmp_ignore_bogus_error_responses" . "1") ;; Enables TCP syncookies. ("net.ipv4.tcp_syncookies" . "1") ;; Disable source routing. ("net.ipv4.conf.all.accept_source_route" . "0") ("net.ipv4.conf.default.accept_source_route" . "0") ("net.ipv6.conf.all.accept_source_route" . "0") ("net.ipv6.conf.default.accept_source_route" . "0") ;; Enable reverse path filtering to prevent IP spoofing and ;; mitigate vulnerabilities such as CVE-2019-14899. ;; https://forums.whonix.org/t/enable-reverse-path-filtering/8594 ("net.ipv4.conf.default.rp_filter" . "1") ("net.ipv4.conf.all.rp_filter" . "1") ;; meta end ;; Disables SACK as it is commonly exploited and likely not needed. ;; https://forums.whonix.org/t/disabling-tcp-sack-dsack-fack/8109 ;; ("net.ipv4.tcp_sack" . "0") ;; ("net.ipv4.tcp_dsack" . "0") ;; ("net.ipv4.tcp_fack" . "0") ;; meta start ;; project Kicksecure ;; category networking and security ;; description ;; disable IPv4 TCP Timestamps ("net.ipv4.tcp_timestamps" . "0") ;; meta end ;; Only allow the SysRq key to be used for shutdowns and the ;; Secure Attention Key (SAK). ;; ;; https://forums.whonix.org/t/sysrq-magic-sysrq-key/8079/ ("kernel.sysrq" . "132") ;; Restrict loading TTY line disciplines to CAP_SYS_MODULE to prevent ;; unprivileged attackers from loading vulnerable line disciplines ;; with the TIOCSETD ioctl which has been used in exploits before ;; such as https://a13xp0p0v.github.io/2017/03/24/CVE-2017-2636.html ;; ;; https://lkml.org/lkml/2019/4/15/890 ("dev.tty.ldisc_autoload" . "0") ;; Restrict the userfaultfd() syscall to root as it can make heap sprays ;; easier. ;; ;; https://duasynt.com/blog/linux-kernel-heap-spray ("vm.unprivileged_userfaultfd" . "0") ;; Let the kernel only swap if it is absolutely necessary. ;; Better not be set to zero: ;; - https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Performance_Tuning_Guide/s-memory-tunables.html ;; - https://en.wikipedia.org/wiki/Swappiness ("vm.swappiness" . "1") ;; Disallow kernel profiling by users without CAP_SYS_ADMIN ;; https://www.kernel.org/doc/Documentation/sysctl/kernel.txt ("kernel.perf_event_paranoid" . "3") ;; Do not accept router advertisments ("net.ipv6.conf.all.accept_ra" . "0") ("net.ipv6.conf.default.accept_ra" . "0") ;; Copyright (C) 2019 - 2022 ENCRYPTED SUPPORT LP ;; See the file COPYING for copying conditions. ;; Prevent kernel info leaks in console during boot. ;; https://phabricator.whonix.org/T950 ("kernel.printk" . "3 3 3 3") ;; NOTE: ;; For higher verbosity, the user might also want to delete file ;; /etc/default/grub.d/41_quiet.cfg ;; (or out-comment its settings). ;; ;; Alternatively, the user could consider to install the debug-misc package, ;; which will undo the settings found here. ))