linux-stable.git/Documentation/admin-guide, branch linux-5.17.y

random: fix sysctl documentation nits

2022-05-30T07:27:12+00:00

commit 069c4ea6871c18bd368f27756e0f91ffb524a788 upstream.

A semicolon was missing, and the almost-alphabetical-but-not ordering
was confusing, so regroup these by category instead.

Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Greg Kroah-Hartman

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

2022-05-30T07:27:10+00:00

commit d97c68d178fbf8aaaf21b69b446f2dfb13909316 upstream.

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 
Signed-off-by: Greg Kroah-Hartman

random: remove ifdef'd out interrupt bench

2022-05-30T07:27:05+00:00

commit 95e6060c20a7f5db60163274c5222a725ac118f9 upstream.

With tools like kbench9000 giving more finegrained responses, and this
basically never having been used ever since it was initially added,
let's just get rid of this. There *is* still work to be done on the
interrupt handler, but this really isn't the way it's being developed.

Cc: Theodore Ts'o 
Reviewed-by: Eric Biggers 
Reviewed-by: Dominik Brodowski 
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Greg Kroah-Hartman

random: always wake up entropy writers after extraction

2022-05-30T07:27:03+00:00

commit 489c7fc44b5740d377e8cfdbf0851036e493af00 upstream.

Now that POOL_BITS == POOL_MIN_BITS, we must unconditionally wake up
entropy writers after every extraction. Therefore there's no point of
write_wakeup_threshold, so we can move it to the dustbin of unused
compatibility sysctls. While we're at it, we can fix a small comparison
where we were waking up after <= min rather than < min.

Cc: Theodore Ts'o 
Suggested-by: Eric Biggers 
Reviewed-by: Eric Biggers 
Reviewed-by: Dominik Brodowski 
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Greg Kroah-Hartman

docs: sysctl/kernel: add missing bit to panic_print

2022-04-08T11:59:03+00:00

commit a1ff1de00db21ecb956213f046b79741b64c6b65 upstream.

Patch series "Some improvements on panic_print".

This is a mix of a documentation fix with some additions to the
"panic_print" syscall / parameter.  The goal here is being able to collect
all CPUs backtraces during a panic event and also to enable "panic_print"
in a kdump event - details of the reasoning and design choices in the
patches.

This patch (of 3):

Commit de6da1e8bcf0 ("panic: add an option to replay all the printk
message in buffer") added a new bit to the sysctl/kernel parameter
"panic_print", but the documentation was added only in
kernel-parameters.txt, not in the sysctl guide.

Fix it here by adding bit 5 to sysctl admin-guide documentation.

[rdunlap@infradead.org: fix table format warning]
  Link: https://lkml.kernel.org/r/20220109055635.6999-1-rdunlap@infradead.org

Link: https://lkml.kernel.org/r/20211109202848.610874-1-gpiccoli@igalia.com
Link: https://lkml.kernel.org/r/20211109202848.610874-2-gpiccoli@igalia.com
Fixes: de6da1e8bcf0 ("panic: add an option to replay all the printk message in buffer")
Signed-off-by: Guilherme G. Piccoli 
Reviewed-by: Feng Tang 
Cc: Luis Chamberlain 
Cc: Kees Cook 
Cc: Iurii Zaikin 
Cc: Samuel Iglesias Gonsalvez 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

vsprintf: Fix %pK with kptr_restrict == 0

2022-04-08T11:57:49+00:00

[ Upstream commit 84842911322fc6a02a03ab9e728a48c691fe3efd ]

Although kptr_restrict is set to 0 and the kernel is booted with
no_hash_pointers parameter, the content of /proc/vmallocinfo is
lacking the real addresses.

  / # cat /proc/vmallocinfo
  0x(ptrval)-0x(ptrval)    8192 load_module+0xc0c/0x2c0c pages=1 vmalloc
  0x(ptrval)-0x(ptrval)   12288 start_kernel+0x4e0/0x690 pages=2 vmalloc
  0x(ptrval)-0x(ptrval)   12288 start_kernel+0x4e0/0x690 pages=2 vmalloc
  0x(ptrval)-0x(ptrval)    8192 _mpic_map_mmio.constprop.0+0x20/0x44 phys=0x80041000 ioremap
  0x(ptrval)-0x(ptrval)   12288 _mpic_map_mmio.constprop.0+0x20/0x44 phys=0x80041000 ioremap
    ...

According to the documentation for /proc/sys/kernel/, %pK is
equivalent to %p when kptr_restrict is set to 0.

Fixes: 5ead723a20e0 ("lib/vsprintf: no_hash_pointers prints all addresses as unhashed")
Signed-off-by: Christophe Leroy 
Reviewed-by: Petr Mladek 
Signed-off-by: Petr Mladek 
Link: https://lore.kernel.org/r/107476128e59bff11a309b5bf7579a1753a41aca.1645087605.git.christophe.leroy@csgroup.eu
Signed-off-by: Sasha Levin

Merge tag 'x86_bugs_for_v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-03-08T01:29:47+00:00

Pull x86 spectre fixes from Borislav Petkov:

 - Mitigate Spectre v2-type Branch History Buffer attacks on machines
   which support eIBRS, i.e., the hardware-assisted speculation
   restriction after it has been shown that such machines are vulnerable
   even with the hardware mitigation.

 - Do not use the default LFENCE-based Spectre v2 mitigation on AMD as
   it is insufficient to mitigate such attacks. Instead, switch to
   retpolines on all AMD by default.

 - Update the docs and add some warnings for the obviously vulnerable
   cmdline configurations.

* tag 'x86_bugs_for_v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation: Warn about eIBRS + LFENCE + Unprivileged eBPF + SMT
  x86/speculation: Warn about Spectre v2 LFENCE mitigation
  x86/speculation: Update link to AMD speculation whitepaper
  x86/speculation: Use generic retpoline by default on AMD
  x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting
  Documentation/hw-vuln: Update spectre doc
  x86/speculation: Add eIBRS + Retpoline options
  x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE

proc: fix documentation and description of pagemap

2022-03-05T19:08:33+00:00

Since bit 57 was exported for uffd-wp write-protected (commit
fb8e37f35a2f: "mm/pagemap: export uffd-wp protection information"),
fixing it can reduce some unnecessary confusion.

Link: https://lkml.kernel.org/r/20220301044538.3042713-1-yun.zhou@windriver.com
Fixes: fb8e37f35a2fe1 ("mm/pagemap: export uffd-wp protection information")
Signed-off-by: Yun Zhou 
Reviewed-by: Peter Xu 
Cc: Jonathan Corbet 
Cc: Tiberiu A Georgescu 
Cc: Florian Schmidt 
Cc: Ivan Teterevkov 
Cc: SeongJae Park 
Cc: Yang Shi 
Cc: David Hildenbrand 
Cc: Axel Rasmussen 
Cc: Miaohe Lin 
Cc: Andrea Arcangeli 
Cc: Colin Cross 
Cc: Alistair Popple 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86/speculation: Update link to AMD speculation whitepaper

2022-02-28T17:37:12+00:00

Update the link to the "Software Techniques for Managing Speculation
on AMD Processors" whitepaper.

Signed-off-by: Kim Phillips 
Signed-off-by: Borislav Petkov

Documentation/hw-vuln: Update spectre doc

2022-02-21T09:21:41+00:00

Update the doc with the new fun.

  [ bp: Massage commit message. ]

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov 
Reviewed-by: Thomas Gleixner