kernel/linux.git/drivers/char/Kconfig, branch v6.6.132

char: add HAS_IOPORT dependencies

2023-05-31T18:17:29+00:00

In a future patch HAS_IOPORT=n will result in inb()/outb() and friends not being declared. We thus need to add HAS_IOPORT as dependency for those drivers using them. Co-developed-by: Arnd Bergmann Signed-off-by: Arnd Bergmann Signed-off-by: Niklas Schnelle Link: https://lore.kernel.org/r/20230522105049.1467313-4-schnelle@linux.ibm.com Signed-off-by: Greg Kroah-Hartman

char: pcmcia: remove all the drivers

2023-03-09T16:30:27+00:00

These char PCMCIA drivers are buggy[1] and receive only minimal care. It was concluded[2], that we should try to remove most pcmcia drivers completely. Let's start with these char broken one. Note that I also removed a UAPI header: include/uapi/linux/cm4000_cs.h. I found only coccinelle tests mentioning some ioctl constants from that file. But they are not actually used. Anyway, should someone complain, we may reintroduce the header (or its parts). [1] https://lore.kernel.org/all/f41c2765-80e0-48bc-b1e4-8cfd3230fd4a@www.fastmail.com/ [2] https://lore.kernel.org/all/c5b39544-a4fb-4796-a046-0b9be9853787@app.fastmail.com/ Signed-off-by: Jiri Slaby (SUSE) Cc: "Hyunwoo Kim" Cc: Harald Welte Cc: Lubomir Rintel Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Acked-by: Dominik Brodowski Reviewed-by: Arnd Bergmann Link: https://lore.kernel.org/r/20230222092302.6348-2-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

random: use random.trust_{bootloader,cpu} command line option only

2022-11-18T01:18:10+00:00

It's very unusual to have both a command line option and a compile time option, and apparently that's confusing to people. Also, basically everybody enables the compile time option now, which means people who want to disable this wind up having to use the command line option to ensure that anyway. So just reduce the number of moving pieces and nix the compile time option in favor of the more versatile command line option. Signed-off-by: Jason A. Donenfeld

Merge tag 'char-misc-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

2022-08-04T18:05:48+00:00

Pull char / misc driver updates from Greg KH: "Here is the large set of char and misc and other driver subsystem changes for 6.0-rc1. Highlights include: - large set of IIO driver updates, additions, and cleanups - new habanalabs device support added (loads of register maps much like GPUs have) - soundwire driver updates - phy driver updates - slimbus driver updates - tiny virt driver fixes and updates - misc driver fixes and updates - interconnect driver updates - hwtracing driver updates - fpga driver updates - extcon driver updates - firmware driver updates - counter driver update - mhi driver fixes and updates - binder driver fixes and updates - speakup driver fixes All of these have been in linux-next for a while without any reported problems" * tag 'char-misc-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (634 commits) drivers: lkdtm: fix clang -Wformat warning char: remove VR41XX related char driver misc: Mark MICROCODE_MINOR unused spmi: trace: fix stack-out-of-bound access in SPMI tracing functions dt-bindings: iio: adc: Add compatible for MT8188 iio: light: isl29028: Fix the warning in isl29028_remove() iio: accel: sca3300: Extend the trigger buffer from 16 to 32 bytes iio: fix iio_format_avail_range() printing for none IIO_VAL_INT iio: adc: max1027: unlock on error path in max1027_read_single_value() iio: proximity: sx9324: add empty line in front of bullet list iio: magnetometer: hmc5843: Remove duplicate 'the' iio: magn: yas530: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: magnetometer: ak8974: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: veml6030: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: vcnl4035: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: vcnl4000: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: tsl2591: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() iio: light: tsl2583: Use DEFINE_RUNTIME_DEV_PM_OPS and pm_ptr() iio: light: isl29028: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() iio: light: gp2ap002: Switch to DEFINE_RUNTIME_DEV_PM_OPS and pm_ptr() ...

char: remove VR41XX related char driver

2022-07-28T14:12:33+00:00

Commit d3164e2f3b0a ("MIPS: Remove VR41xx support") removed support for MIPS VR41xx platform, so remove exclusive drivers for this platform, too. Signed-off-by: Thomas Bogendoerfer Link: https://lore.kernel.org/r/20220716130802.11660-1-tsbogend@alpha.franken.de Signed-off-by: Greg Kroah-Hartman

random: remove CONFIG_ARCH_RANDOM

2022-07-18T13:03:37+00:00

When RDRAND was introduced, there was much discussion on whether it should be trusted and how the kernel should handle that. Initially, two mechanisms cropped up, CONFIG_ARCH_RANDOM, a compile time switch, and "nordrand", a boot-time switch. Later the thinking evolved. With a properly designed RNG, using RDRAND values alone won't harm anything, even if the outputs are malicious. Rather, the issue is whether those values are being *trusted* to be good or not. And so a new set of options were introduced as the real ones that people use -- CONFIG_RANDOM_TRUST_CPU and "random.trust_cpu". With these options, RDRAND is used, but it's not always credited. So in the worst case, it does nothing, and in the best case, maybe it helps. Along the way, CONFIG_ARCH_RANDOM's meaning got sort of pulled into the center and became something certain platforms force-select. The old options don't really help with much, and it's a bit odd to have special handling for these instructions when the kernel can deal fine with the existence or untrusted existence or broken existence or non-existence of that CPU capability. Simplify the situation by removing CONFIG_ARCH_RANDOM and using the ordinary asm-generic fallback pattern instead, keeping the two options that are actually used. For now it leaves "nordrand" for now, as the removal of that will take a different route. Acked-by: Michael Ellerman Acked-by: Catalin Marinas Acked-by: Borislav Petkov Acked-by: Heiko Carstens Acked-by: Greg Kroah-Hartman Signed-off-by: Jason A. Donenfeld

random: credit cpu and bootloader seeds by default

2022-06-10T09:29:48+00:00

This commit changes the default Kconfig values of RANDOM_TRUST_CPU and RANDOM_TRUST_BOOTLOADER to be Y by default. It does not change any existing configs or change any kernel behavior. The reason for this is several fold. As background, I recently had an email thread with the kernel maintainers of Fedora/RHEL, Debian, Ubuntu, Gentoo, Arch, NixOS, Alpine, SUSE, and Void as recipients. I noted that some distros trust RDRAND, some trust EFI, and some trust both, and I asked why or why not. There wasn't really much of a "debate" but rather an interesting discussion of what the historical reasons have been for this, and it came up that some distros just missed the introduction of the bootloader Kconfig knob, while another didn't want to enable it until there was a boot time switch to turn it off for more concerned users (which has since been added). The result of the rather uneventful discussion is that every major Linux distro enables these two options by default. While I didn't have really too strong of an opinion going into this thread -- and I mostly wanted to learn what the distros' thinking was one way or another -- ultimately I think their choice was a decent enough one for a default option (which can be disabled at boot time). I'll try to summarize the pros and cons: Pros: - The RNG machinery gets initialized super quickly, and there's no messing around with subsequent blocking behavior. - The bootloader mechanism is used by kexec in order for the prior kernel to initialize the RNG of the next kernel, which increases the entropy available to early boot daemons of the next kernel. - Previous objections related to backdoors centered around Dual_EC_DRBG-like kleptographic systems, in which observing some amount of the output stream enables an adversary holding the right key to determine the entire output stream. This used to be a partially justified concern, because RDRAND output was mixed into the output stream in varying ways, some of which may have lacked pre-image resistance (e.g. XOR or an LFSR). But this is no longer the case. Now, all usage of RDRAND and bootloader seeds go through a cryptographic hash function. This means that the CPU would have to compute a hash pre-image, which is not considered to be feasible (otherwise the hash function would be terribly broken). - More generally, if the CPU is backdoored, the RNG is probably not the realistic vector of choice for an attacker. - These CPU or bootloader seeds are far from being the only source of entropy. Rather, there is generally a pretty huge amount of entropy, not all of which is credited, especially on CPUs that support instructions like RDRAND. In other words, assuming RDRAND outputs all zeros, an attacker would *still* have to accurately model every single other entropy source also in use. - The RNG now reseeds itself quite rapidly during boot, starting at 2 seconds, then 4, then 8, then 16, and so forth, so that other sources of entropy get used without much delay. - Paranoid users can set random.trust_{cpu,bootloader}=no in the kernel command line, and paranoid system builders can set the Kconfig options to N, so there's no reduction or restriction of optionality. - It's a practical default. - All the distros have it set this way. Microsoft and Apple trust it too. Bandwagon. Cons: - RDRAND *could* still be backdoored with something like a fixed key or limited space serial number seed or another indexable scheme like that. (However, it's hard to imagine threat models where the CPU is backdoored like this, yet people are still okay making *any* computations with it or connecting it to networks, etc.) - RDRAND *could* be defective, rather than backdoored, and produce garbage that is in one way or another insufficient for crypto. - Suggesting a *reduction* in paranoia, as this commit effectively does, may cause some to question my personal integrity as a "security person". - Bootloader seeds and RDRAND are generally very difficult if not all together impossible to audit. Keep in mind that this doesn't actually change any behavior. This is just a change in the default Kconfig value. The distros already are shipping kernels that set things this way. Ard made an additional argument in [1]: We're at the mercy of firmware and micro-architecture anyway, given that we are also relying on it to ensure that every instruction in the kernel's executable image has been faithfully copied to memory, and that the CPU implements those instructions as documented. So I don't think firmware or ISA bugs related to RNGs deserve special treatment - if they are broken, we should quirk around them like we usually do. So enabling these by default is a step in the right direction IMHO. In [2], Phil pointed out that having this disabled masked a bug that CI otherwise would have caught: A clean 5.15.45 boots cleanly, whereas a downstream kernel shows the static key warning (but it does go on to boot). The significant difference is that our defconfigs set CONFIG_RANDOM_TRUST_BOOTLOADER=y defining that on top of multi_v7_defconfig demonstrates the issue on a clean 5.15.45. Conversely, not setting that option in a downstream kernel build avoids the warning [1] https://lore.kernel.org/lkml/CAMj1kXGi+ieviFjXv9zQBSaGyyzeGW_VpMpTLJK8PJb2QHEQ-w@mail.gmail.com/ [2] https://lore.kernel.org/lkml/c47c42e3-1d56-5859-a6ad-976a1a3381c6@raspberrypi.com/ Cc: Theodore Ts'o Reviewed-by: Ard Biesheuvel Signed-off-by: Jason A. Donenfeld

char: ttyprintk: register console

2022-04-22T14:24:47+00:00

Register a console in the ttyprintk driver so that it can be selected for /dev/console with console=ttyprintk on the kernel command line, similar to other console drivers. Signed-off-by: Vincent Whitchurch Link: https://lore.kernel.org/r/20220215141750.92808-1-vincent.whitchurch@axis.com Signed-off-by: Greg Kroah-Hartman

random: treat bootloader trust toggle the same way as cpu trust toggle

2022-03-25T14:49:40+00:00

If CONFIG_RANDOM_TRUST_CPU is set, the RNG initializes using RDRAND. But, the user can disable (or enable) this behavior by setting `random.trust_cpu=0/1` on the kernel command line. This allows system builders to do reasonable things while avoiding howls from tinfoil hatters. (Or vice versa.) CONFIG_RANDOM_TRUST_BOOTLOADER is basically the same thing, but regards the seed passed via EFI or device tree, which might come from RDRAND or a TPM or somewhere else. In order to allow distros to more easily enable this while avoiding those same howls (or vice versa), this commit adds the corresponding `random.trust_bootloader=0/1` toggle. Cc: Theodore Ts'o Cc: Graham Christensen Reviewed-by: Ard Biesheuvel Reviewed-by: Dominik Brodowski Link: https://github.com/NixOS/nixpkgs/pull/165355 Signed-off-by: Jason A. Donenfeld

char: move RANDOM_TRUST_CPU & RANDOM_TRUST_BOOTLOADER into the Character devices menu

2021-08-16T17:02:19+00:00

Include RANDOM_TRUST_CPU and RANDOM_TRUST_BOOTLOADER inside the "Character devices" menu so that they are listed (presented) with other Character devices. Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Cc: Hsin-Yi Wang Cc: Theodore Ts'o Signed-off-by: Randy Dunlap Link: https://lore.kernel.org/r/20210816000531.17934-1-rdunlap@infradead.org Signed-off-by: Greg Kroah-Hartman