Division by zero triggers an arithmetic exception and should not be very
common. Predict this.
No functional change intended.
MFC after: 1 week
Sponsored by: NVIDIA Networking
glibc-based interface.
Unfortunately, the glibc maintainers, despite knowing the existence
of the FreeBSD qsort_r(3) interface in 2004 and refused to add the
same interface to glibc based on grounds of the lack of standardization
and portability concerns, has decided it was a good idea to introduce
their own qsort_r(3) interface in 2007 as a GNU extension with a
slightly different and incompatible interface.
With the adoption of their interface as POSIX standard, let's switch
to the same prototype, there is no need to remain incompatible.
C++ and C applications written for the historical FreeBSD interface
get source level compatibility when building in C++ mode, or when
building with a C compiler with C11 generics support, provided that
the caller passes a fifth parameter of qsort_r() that exactly matches
the historical FreeBSD comparator function pointer type and does not
redefine the historical qsort_r(3) prototype in their source code.
Symbol versioning is used to keep old binaries working.
MFC: never
Relnotes: yes
Reviewed by: cem, imp, hps, pauamma
Differential revision: https://reviews.freebsd.org/D17083
Unused since ba96f37758 ("Use __builtin for various mem* and b* (e.g. bzero)
routines.")
File name remains to reduce churn.
Sponsored by: Rubicon Communications, LLC ("Netgate")
The kernel was migrated to memcmp in ba96f37758 ("Use __builtin
for various mem* and b* (e.g. bzero) routines.") and there are no
remaining architectures using the file.
Sponsored by: Rubicon Communications, LLC ("Netgate")
If code calls arc4random(), and our RNG is not yet seeded and
random_bypass_before_seeding is true, we'll compute a key using the
SHA256 hash of some hopefully hard-to-predict data, including the
contents of an uninitialized stack buffer (which is also the output
buffer).
When KMSAN is enabled, this use of uninitialized state propagtes through
to the arc4random() output, resulting in false positives. To address
this, lie to KMSAN and explicitly mark the buffer as initialized.
Reviewed by: cem (previous version)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D31510
These ones were unambiguous cases where the Foundation was the only
listed copyright holder (in the associated license block).
Sponsored by: The FreeBSD Foundation
There is no need to read the same variable to check if the CPU supports
crc32c instructions.
Reviewed by: arichardson, kib, markj
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D31274
strcspn should never have had the __restrict keywords. While both of
these strings are const, it may have unindended side effects. While this
is the kernel, the POSIX definition also omits restrict.
Reviewed by: imp@
Pull Request: https://github.com/freebsd/freebsd-src/pull/497
documention.
Commit SVN r364219 / Git 8a0edc914f changed random(9) to be a shim around
prng32(9) and inadvertently caused random(9) to begin returning numbers in the
range [0,2^32-1] instead of [0,2^31-1], where the latter has been the documented
range for decades.
The increased output range has been identified as the source of numerous bugs in
code written against the historical output range e.g. ipfw "prob" rules and
stats(3) are known to be affected, and a non-exhaustive audit of the tree
identified other random(9) consumers which are also likely affected.
As random(9) is deprecated and slated for eventual removal in 14.0, consumers
should gradually be audited and migrated to prng(9).
Submitted by: Loic Prylli <lprylli@netflix.com>
Obtained from: Netflix
Reviewed by: cem, delphij, imp
MFC after: 1 day
MFC to: stable/13, releng/13.0
Differential Revision: https://reviews.freebsd.org/D29385
This reverts commit 710e45c4b8.
It breaks for some corner cases on big endian ppc64.
Given the stage of the release process it is best to revert for now.
Reported by: jhibbits
This avoids a SIGILL when running these tests on QEMU (which
defaults to a basic amd64 CPU without SSE4.2).
This commit also tests the table-based implementations in addition to
testing the hw-accelerated crc32 versions.
Reviewed By: cem, kib, markj
Differential Revision: https://reviews.freebsd.org/D28395
The previous code neglected to use primitives which can find the end
of the string without having to branch on every character.
While here augment the somewhat misleading commentary -- strlen as
implemented here leaves performance on the table, especially so for
userspace. Every arch should get a dedicated variant instead.
In the meantime this commit lessens the problem.
Tested with glibc test suite.
Naive test just calling strlen in a loop on Haswell (ops/s):
$(perl -e "print 'A' x 3"):
before: 211198039
after: 338626619
$(perl -e "print 'A' x 100"):
before: 83151997
after: 98285919
This is all code only run on ARMv4 and ARMv5. Support for these have
been dropped from FreeBSD.
Differential Revision: https://reviews.freebsd.org/D28314
There is no functional change for the existing Fortuna random(4)
implementation, which remains the default in GENERIC.
In the FenestrasX model, when the root CSPRNG is reseeded from pools due to
an (infrequent) timer, child CSPRNGs can cheaply detect this condition and
reseed. To do so, they just need to track an additional 64-bit value in the
associated state, and compare it against the root seed version (generation)
on random reads.
This revision integrates arc4random(9) into that model without substantially
changing the design or implementation of arc4random(9). The motivation is
that arc4random(9) is immediately reseeded when the backing random(4)
implementation has additional entropy. This is arguably most important
during boot, when fenestrasX is reseeding at 1, 3, 9, 27, etc., second
intervals. Today, arc4random(9) has a hardcoded 300 second reseed window.
Without this mechanism, if arc4random(9) gets weak entropy during initial
seed (and arc4random(9) is used early in boot, so this is quite possible),
it may continue to emit poorly seeded output for 5 minutes. The FenestrasX
push-reseed scheme corrects consumers, like arc4random(9), as soon as
possible.
Reviewed by: markm
Approved by: csprng (markm)
Differential Revision: https://reviews.freebsd.org/D22838
Doing it this way eliminates the assumption about homogeneous support
for the feature, since HWCAP values are only set if support is present
on all CPUs.
Reviewed by: tuexen, markj
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D26032
Save 7k of text space by using simpler crc32 for standalone case. we
don't need all that fancy optimization in the boot loader, so use a
simplified version of the CRC function. We could save more by doing it
one bit at a time rather than 32, but this is the biggest savings at
the smallest performance hit.
With LUA and verfied exec, gptboot, gptzfsboot and friends are pushing
the ~530k limit and every little bit helps.
Reviewed By: allanjude
Differential Revision: https://reviews.freebsd.org/D24225
Add prng(9) as a replacement for random(9) in the kernel.
There are two major differences from random(9) and random(3):
- General prng(9) APIs (prng32(9), etc) do not guarantee an
implementation or particular sequence; they should not be used for
repeatable simulations.
- However, specific named API families are also exposed (for now: PCG),
and those are expected to be repeatable (when so-guaranteed by the named
algorithm).
Some minor differences from random(3) and earlier random(9):
- PRNG state for the general prng(9) APIs is per-CPU; this eliminates
contention on PRNG state in SMP workloads. Each PCPU generator in an
SMP system produces a unique sequence.
- Better statistical properties than the Park-Miller ("minstd") PRNG
(longer period, uniform distribution in all bits, passes
BigCrush/PractRand analysis).
- Faster than Park-Miller ("minstd") PRNG -- no division is required to
step PCG-family PRNGs.
For now, random(9) becomes a thin shim around prng32(). Eventually I
would like to mechanically switch consumers over to the explicit API.
Reviewed by: kib, markj (previous version both)
Discussed with: markm
Differential Revision: https://reviews.freebsd.org/D25916
This variant get a random number up to the limit passed as the argument.
This is simply a copy of the libc version.
Sponsored-by: The FreeBSD Foundation
Reviewed by: cem, hselasky (previous version)
Differential Revision: https://reviews.freebsd.org/D24962
r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked).
Use it in preparation for a general review of all nodes.
This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.
Mark all obvious cases as MPSAFE. All entries that haven't been marked
as MPSAFE before are by default marked as NEEDGIANT
Approved by: kib (mentor, blanket)
Commented by: kib, gallatin, melifaro
Differential Revision: https://reviews.freebsd.org/D23718
srandom(9) is meaningless on SMP systems or any system with, say,
interrupts. One could never rely on random(9) to produce a reproducible
sequence of outputs on the basis of a specific srandom() seed because the
global state was shared by all kernel contexts. As such, removing it is
literally indistinguishable to random(9) consumers (as compared with
retaining it).
Mark random(9) as deprecated and slated for quick removal. This is not to
say we intend to remove all fast, non-cryptographic PRNG(s) in the kernel.
It/they just won't be random(9), as it exists today, in either name or
implementation.
Before random(9) is removed, a replacement will be provided and in-tree
consumers will be converted.
Note that despite the name, the random(9) interface does not bear any
resemblance to random(3). Instead, it is the same crummy 1988 Park-Miller
LCG used in libc rand(3).
Update the NetBSD Kernel Concurrency Sanitizer (KCSAN) runtime to work in
the FreeBSD kernel. It is a useful tool for finding data races between
threads executing on different CPUs.
This can be enabled by enabling KCSAN in the kernel config, or by using the
GENERIC-KCSAN amd64 kernel. It works on amd64 and arm64, however the later
needs a compiler change to allow -fsanitize=thread that KCSAN uses.
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D22315
Because of the previous naming scheme the old ID_AA64PFR0_EL1 macro
collided with a potential macro for the register of the same name. To fix
this collision rename these macros.
Sponsored by: DARPA, AFRL
with an eventual goal to convert all legacl zlib callers to the new zlib
version:
* Move generic zlib shims that are not specific to zlib 1.0.4 to
sys/dev/zlib.
* Connect new zlib (1.2.11) to the zlib kernel module, currently built
with Z_SOLO.
* Prefix the legacy zlib (1.0.4) with 'zlib104_' namespace.
* Convert sys/opencrypto/cryptodeflate.c to use new zlib.
* Remove bundled zlib 1.2.3 from ZFS and adapt it to new zlib and make
it depend on the zlib module.
* Fix Z_SOLO build of new zlib.
PR: 229763
Submitted by: Yoshihiro Ota <ota j email ne jp>
Reviewed by: markm (sys/dev/zlib/zlib_kmod.c)
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D19706
rename the source to gsb_crc32.c.
This is a prerequisite of unifying kernel zlib instances.
PR: 229763
Submitted by: Yoshihiro Ota <ota at j.email.ne.jp>
Differential Revision: https://reviews.freebsd.org/D20193
- __predict_false reseeding on entry as it is almost never true.
- don't blindly atomic_cmpset as on x86 it ends up dirtying the cacheline.
it almost ever succeeds per above
- fetch the timestamp prior to getting the cpu number
Reviewed by: cem
Approved by: secteam (delphij)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D20242
It is a useful arc4random wrapper in the kernel for much the same reasons as
in userspace. Move the source to libkern (because kernel build is
restricted to sys/, but userspace can include any file it likes) and build
kernel and libc versions from the same source file.
Copy the documentation from arc4random_uniform(3) to the section 9 page.
While here, add missing arc4random_buf(9) symlink.
Sponsored by: Dell EMC Isilon
As discussed in that commit message, it is a dangerous default. But the
safe default causes enough pain on a variety of platforms that for now,
restore the prior default.
Some of this is self-induced pain we should/could do better about; for
example, programmatic CI systems and VM managers should introduce entropy
from the host for individual VM instances. This is considered a future work
item.
On modern x86 and Power9 systems, this may be wholly unnecessary after
D19928 lands (even in the non-ideal case where early /boot/entropy is
unavailable), because they have fast hardware random sources available early
in boot. But D19928 is not yet landed and we have a host of architectures
which do not provide fast random sources.
This change adds several tunables and diagnostic sysctls, documented
thoroughly in UPDATING and sys/dev/random/random_infra.c.
PR: 230875 (reopens)
Reported by: adrian, jhb, imp, and probably others
Reviewed by: delphij, imp (earlier version), markm (earlier version)
Discussed with: adrian
Approved by: secteam(delphij)
Relnotes: yeah
Security: related
Differential Revision: https://reviews.freebsd.org/D19944
read_random() is/was used, mostly without error checking, in a lot of
very sensitive places in the kernel -- including seeding the widely used
arc4random(9).
Most uses, especially arc4random(9), should block until the device is seeded
rather than proceeding with a bogus or empty seed. I did not spy any
obvious kernel consumers where blocking would be inappropriate (in the
sense that lack of entropy would be ok -- I did not investigate locking
angle thoroughly). In many instances, arc4random_buf(9) or that family
of APIs would be more appropriate anyway; that work was done in r345865.
A minor cleanup was made to the implementation of the READ_RANDOM function:
instead of using a variable-length array on the stack to temporarily store
all full random blocks sufficient to satisfy the requested 'len', only store
a single block on the stack. This has some benefit in terms of reducing
stack usage, reducing memcpy overhead and reducing devrandom output leakage
via the stack. Additionally, the stack block is now safely zeroed if it was
used.
One caveat of this change is that the kern.arandom sysctl no longer returns
zero bytes immediately if the random device is not seeded. This means that
FreeBSD-specific userspace applications which attempted to handle an
unseeded random device may be broken by this change. If such behavior is
needed, it can be replaced by the more portable getrandom(2) GRND_NONBLOCK
option.
On any typical FreeBSD system, entropy is persisted on read/write media and
used to seed the random device very early in boot, and blocking is never a
problem.
This change primarily impacts the behavior of /dev/random on embedded
systems with read-only media that do not configure "nodevice random". We
toggle the default from 'charge on blindly with no entropy' to 'block
indefinitely.' This default is safer, but may cause frustration. Embedded
system designers using FreeBSD have several options. The most obvious is to
plan to have a small writable NVRAM or NAND to persist entropy, like larger
systems. Early entropy can be fed from any loader, or by writing directly
to /dev/random during boot. Some embedded SoCs now provide a fast hardware
entropy source; this would also work for quickly seeding Fortuna. A 3rd
option would be creating an embedded-specific, more simplistic random
module, like that designed by DJB in [1] (this design still requires a small
rewritable media for forward secrecy). Finally, the least preferred option
might be "nodevice random", although I plan to remove this in a subsequent
revision.
To help developers emulate the behavior of these embedded systems on
ordinary workstations, the tunable kern.random.block_seeded_status was
added. When set to 1, it blocks the random device.
I attempted to document this change in random.4 and random.9 and ran into a
bunch of out-of-date or irrelevant or inaccurate content and ended up
rototilling those documents more than I intended to. Sorry. I think
they're in a better state now.
PR: 230875
Reviewed by: delphij, markm (earlier version)
Approved by: secteam(delphij), devrandom(markm)
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D19744
debugfs expects to do non-sleepable allocations
Reviewed by: hps@
MFC after: 1 week
Sponsored by: iX Systems
Differential Revision: https://reviews.freebsd.org/D19259
libc/gmon's mcount was ANSIfied in r124180, with libkern following over
a decade later, in r325988, but some minor discrepancies remained.
Update libc/gmon's mexitcount to an ANSI C function definition, and use
(void) for libkern-only functions that take no arguments.
Reported by: bde
Writing one union member and reading another is technically illegal C,
although we do it in many places in the tree. Use the __DECONST macro
instead, which is (technically) a valid C construct.
Trivial style(9) cleanups to touched lines while here.
Sponsored by: Dell EMC Isilon
