lwn.git/kernel, branch docs-5.10-3

treewide: Convert macro and uses of section(foo) to section("foo")

2020-10-25T21:51:49+00:00

Use a more generic form for __section that requires quotes to avoid complications with clang and gcc differences. Remove the quote operator # from compiler_attributes.h __section macro. Convert all unquoted __section(foo) uses to quoted __section("foo"). Also convert __attribute__((section("foo"))) uses to __section("foo") even if the __attribute__ has multiple list entry forms. Conversion done using the script at: https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl Signed-off-by: Joe Perches Reviewed-by: Nick Desaulniers Reviewed-by: Miguel Ojeda Signed-off-by: Linus Torvalds

kernel/sys.c: fix prototype of prctl_get_tid_address()

2020-10-25T18:44:16+00:00

tid_addr is not a "pointer to (pointer to int in userspace)"; it is in fact a "pointer to (pointer to int in userspace) in userspace". So sparse rightfully complains about passing a kernel pointer to put_user(). Reported-by: kernel test robot Signed-off-by: Rasmus Villemoes Signed-off-by: Linus Torvalds

Merge tag 'timers-urgent-2020-10-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-10-25T18:28:49+00:00

Pull timer fixes from Thomas Gleixner: "A time namespace fix and a matching selftest. The futex absolute timeouts which are based on CLOCK_MONOTONIC require time namespace corrected. This was missed in the original time namesapce support" * tag 'timers-urgent-2020-10-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: selftests/timens: Add a test for futex() futex: Adjust absolute futex timeouts with per time namespace offset

Merge tag 'sched-urgent-2020-10-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-10-25T18:25:16+00:00

Pull scheduler fixes from Thomas Gleixner: "Two scheduler fixes: - A trivial build fix for sched_feat() to compile correctly with CONFIG_JUMP_LABEL=n - Replace a zero lenght array with a flexible array" * tag 'sched-urgent-2020-10-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/features: Fix !CONFIG_JUMP_LABEL case sched: Replace zero-length array with flexible-array

Merge tag 'safesetid-5.10' of git://github.com/micah-morton/linux

2020-10-25T17:45:26+00:00

Pull SafeSetID updates from Micah Morton: "The changes are mostly contained to within the SafeSetID LSM, with the exception of a few 1-line changes to change some ns_capable() calls to ns_capable_setid() -- causing a flag (CAP_OPT_INSETID) to be set that is examined by SafeSetID code and nothing else in the kernel. The changes to SafeSetID internally allow for setting up GID transition security policies, as already existed for UIDs" * tag 'safesetid-5.10' of git://github.com/micah-morton/linux: LSM: SafeSetID: Fix warnings reported by test bot LSM: SafeSetID: Add GID security policy handling LSM: Signal to SafeSetID when setting group IDs

Merge tag '20201024-v4-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/prandom

2020-10-25T17:40:08+00:00

Pull random32 updates from Willy Tarreau: "Make prandom_u32() less predictable. This is the cleanup of the latest series of prandom_u32 experimentations consisting in using SipHash instead of Tausworthe to produce the randoms used by the network stack. The changes to the files were kept minimal, and the controversial commit that used to take noise from the fast_pool (f227e3ec3b5c) was reverted. Instead, a dedicated "net_rand_noise" per_cpu variable is fed from various sources of activities (networking, scheduling) to perturb the SipHash state using fast, non-trivially predictable data, instead of keeping it fully deterministic. The goal is essentially to make any occasional memory leakage or brute-force attempt useless. The resulting code was verified to be very slightly faster on x86_64 than what is was with the controversial commit above, though this remains barely above measurement noise. It was also tested on i386 and arm, and build- tested only on arm64" Link: https://lore.kernel.org/netdev/20200808152628.GA27941@SDF.ORG/ * tag '20201024-v4-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/prandom: random32: add a selftest for the prandom32 code random32: add noise from network and scheduling activity random32: make prandom_u32() output unpredictable

Merge tag 'dma-mapping-5.10-1' of git://git.infradead.org/users/hch/dma-mapping

2020-10-24T19:17:05+00:00

Pull dma-mapping fixes from Christoph Hellwig: - document the new dma_{alloc,free}_pages() API - two fixups for the dma-mapping.h split * tag 'dma-mapping-5.10-1' of git://git.infradead.org/users/hch/dma-mapping: dma-mapping: document dma_{alloc,free}_pages dma-mapping: move more functions to dma-map-ops.h ARM/sa1111: add a missing include of dma-map-ops.h

random32: add noise from network and scheduling activity

2020-10-24T18:21:57+00:00

With the removal of the interrupt perturbations in previous random32 change (random32: make prandom_u32() output unpredictable), the PRNG has become 100% deterministic again. While SipHash is expected to be way more robust against brute force than the previous Tausworthe LFSR, there's still the risk that whoever has even one temporary access to the PRNG's internal state is able to predict all subsequent draws till the next reseed (roughly every minute). This may happen through a side channel attack or any data leak. This patch restores the spirit of commit f227e3ec3b5c ("random32: update the net random state on interrupt and activity") in that it will perturb the internal PRNG's statee using externally collected noise, except that it will not pick that noise from the random pool's bits nor upon interrupt, but will rather combine a few elements along the Tx path that are collectively hard to predict, such as dev, skb and txq pointers, packet length and jiffies values. These ones are combined using a single round of SipHash into a single long variable that is mixed with the net_rand_state upon each invocation. The operation was inlined because it produces very small and efficient code, typically 3 xor, 2 add and 2 rol. The performance was measured to be the same (even very slightly better) than before the switch to SipHash; on a 6-core 12-thread Core i7-8700k equipped with a 40G NIC (i40e), the connection rate dropped from 556k/s to 555k/s while the SYN cookie rate grew from 5.38 Mpps to 5.45 Mpps. Link: https://lore.kernel.org/netdev/20200808152628.GA27941@SDF.ORG/ Cc: George Spelvin Cc: Amit Klein Cc: Eric Dumazet Cc: "Jason A. Donenfeld" Cc: Andy Lutomirski Cc: Kees Cook Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Linus Torvalds Cc: tytso@mit.edu Cc: Florian Westphal Cc: Marc Plumb Tested-by: Sedat Dilek Signed-off-by: Willy Tarreau

random32: make prandom_u32() output unpredictable

2020-10-24T18:21:57+00:00

Non-cryptographic PRNGs may have great statistical properties, but are usually trivially predictable to someone who knows the algorithm, given a small sample of their output. An LFSR like prandom_u32() is particularly simple, even if the sample is widely scattered bits. It turns out the network stack uses prandom_u32() for some things like random port numbers which it would prefer are *not* trivially predictable. Predictability led to a practical DNS spoofing attack. Oops. This patch replaces the LFSR with a homebrew cryptographic PRNG based on the SipHash round function, which is in turn seeded with 128 bits of strong random key. (The authors of SipHash have *not* been consulted about this abuse of their algorithm.) Speed is prioritized over security; attacks are rare, while performance is always wanted. Replacing all callers of prandom_u32() is the quick fix. Whether to reinstate a weaker PRNG for uses which can tolerate it is an open question. Commit f227e3ec3b5c ("random32: update the net random state on interrupt and activity") was an earlier attempt at a solution. This patch replaces it. Reported-by: Amit Klein Cc: Willy Tarreau Cc: Eric Dumazet Cc: "Jason A. Donenfeld" Cc: Andy Lutomirski Cc: Kees Cook Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Linus Torvalds Cc: tytso@mit.edu Cc: Florian Westphal Cc: Marc Plumb Fixes: f227e3ec3b5c ("random32: update the net random state on interrupt and activity") Signed-off-by: George Spelvin Link: https://lore.kernel.org/netdev/20200808152628.GA27941@SDF.ORG/ [ willy: partial reversal of f227e3ec3b5c; moved SIPROUND definitions to prandom.h for later use; merged George's prandom_seed() proposal; inlined siprand_u32(); replaced the net_rand_state[] array with 4 members to fix a build issue; cosmetic cleanups to make checkpatch happy; fixed RANDOM32_SELFTEST build ] Signed-off-by: Willy Tarreau

Merge tag 'trace-v5.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2020-10-24T00:09:38+00:00

Pull tracing ring-buffer fix from Steven Rostedt: "The success return value of ring_buffer_resize() is stated to be zero and checked that way. But it was incorrectly returning the size allocated. Also, a fix to a comment" * tag 'trace-v5.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ring-buffer: Update the description for ring_buffer_wait ring-buffer: Return 0 on success from ring_buffer_resize()

lwn.git/kernel, branch docs-5.10-3

treewide: Convert macro and uses of __section(foo) to __section("foo")

kernel/sys.c: fix prototype of prctl_get_tid_address()

Merge tag 'timers-urgent-2020-10-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Merge tag 'sched-urgent-2020-10-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Merge tag 'safesetid-5.10' of git://github.com/micah-morton/linux

Merge tag '20201024-v4-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/prandom

Merge tag 'dma-mapping-5.10-1' of git://git.infradead.org/users/hch/dma-mapping

random32: add noise from network and scheduling activity

random32: make prandom_u32() output unpredictable

Merge tag 'trace-v5.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

treewide: Convert macro and uses of section(foo) to section("foo")