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2021-03-03random: fix the RNDRESEEDCRNG ioctlEric Biggers1-1/+1
commit 11a0b5e0ec8c13bef06f7414f9e914506140d5cb upstream. The RNDRESEEDCRNG ioctl reseeds the primary_crng from itself, which doesn't make sense. Reseed it from the input_pool instead. Fixes: d848e5f8e1eb ("random: add new ioctl RNDRESEEDCRNG") Cc: stable@vger.kernel.org Cc: linux-crypto@vger.kernel.org Cc: Andy Lutomirski <luto@kernel.org> Cc: Jann Horn <jannh@google.com> Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jann Horn <jannh@google.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20210112192818.69921-1-ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-18random32: make prandom_u32() output unpredictableGeorge Spelvin1-1/+0
commit c51f8f88d705e06bd696d7510aff22b33eb8e638 upstream. 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 <aksecurity@gmail.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Eric Dumazet <edumazet@google.com> Cc: "Jason A. Donenfeld" <Jason@zx2c4.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: tytso@mit.edu Cc: Florian Westphal <fw@strlen.de> Cc: Marc Plumb <lkml.mplumb@gmail.com> Fixes: f227e3ec3b5c ("random32: update the net random state on interrupt and activity") Signed-off-by: George Spelvin <lkml@sdf.org> 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 ] [wt: backported to 4.14 -- various context adjustments; timer API change] Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-07random32: update the net random state on interrupt and activityWilly Tarreau1-0/+1
commit f227e3ec3b5cad859ad15666874405e8c1bbc1d4 upstream. This modifies the first 32 bits out of the 128 bits of a random CPU's net_rand_state on interrupt or CPU activity to complicate remote observations that could lead to guessing the network RNG's internal state. Note that depending on some network devices' interrupt rate moderation or binding, this re-seeding might happen on every packet or even almost never. In addition, with NOHZ some CPUs might not even get timer interrupts, leaving their local state rarely updated, while they are running networked processes making use of the random state. For this reason, we also perform this update in update_process_times() in order to at least update the state when there is user or system activity, since it's the only case we care about. Reported-by: Amit Klein <aksecurity@gmail.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric Dumazet <edumazet@google.com> Cc: "Jason A. Donenfeld" <Jason@zx2c4.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: <stable@vger.kernel.org> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-13random: always use batched entropy for get_random_u{32,64}Jason A. Donenfeld1-16/+4
commit 69efea712f5b0489e67d07565aad5c94e09a3e52 upstream. It turns out that RDRAND is pretty slow. Comparing these two constructions: for (i = 0; i < CHACHA_BLOCK_SIZE; i += sizeof(ret)) arch_get_random_long(&ret); and long buf[CHACHA_BLOCK_SIZE / sizeof(long)]; extract_crng((u8 *)buf); it amortizes out to 352 cycles per long for the top one and 107 cycles per long for the bottom one, on Coffee Lake Refresh, Intel Core i9-9880H. And importantly, the top one has the drawback of not benefiting from the real rng, whereas the bottom one has all the nice benefits of using our own chacha rng. As get_random_u{32,64} gets used in more places (perhaps beyond what it was originally intended for when it was introduced as get_random_{int,long} back in the md5 monstrosity era), it seems like it might be a good thing to strengthen its posture a tiny bit. Doing this should only be stronger and not any weaker because that pool is already initialized with a bunch of rdrand data (when available). This way, we get the benefits of the hardware rng as well as our own rng. Another benefit of this is that we no longer hit pitfalls of the recent stream of AMD bugs in RDRAND. One often used code pattern for various things is: do { val = get_random_u32(); } while (hash_table_contains_key(val)); That recent AMD bug rendered that pattern useless, whereas we're really very certain that chacha20 output will give pretty distributed numbers, no matter what. So, this simplification seems better both from a security perspective and from a performance perspective. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/20200221201037.30231-1-Jason@zx2c4.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-11Revert "char/random: silence a lockdep splat with printk()"Greg Kroah-Hartman1-3/+2
This reverts commit 28820c5802f9f83c655ab09ccae8289103ce1490 which is commit 1b710b1b10eff9d46666064ea25f079f70bc67a8 upstream. It causes problems here just like it did in 4.19.y and odds are it will be reverted upstream as well. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Qian Cai <cai@lca.pw> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-28char/random: silence a lockdep splat with printk()Sergey Senozhatsky1-2/+3
[ Upstream commit 1b710b1b10eff9d46666064ea25f079f70bc67a8 ] Sergey didn't like the locking order, uart_port->lock -> tty_port->lock uart_write (uart_port->lock) __uart_start pl011_start_tx pl011_tx_chars uart_write_wakeup tty_port_tty_wakeup tty_port_default tty_port_tty_get (tty_port->lock) but those code is so old, and I have no clue how to de-couple it after checking other locks in the splat. There is an onging effort to make all printk() as deferred, so until that happens, workaround it for now as a short-term fix. LTP: starting iogen01 (export LTPROOT; rwtest -N iogen01 -i 120s -s read,write -Da -Dv -n 2 500b:$TMPDIR/doio.f1.$$ 1000b:$TMPDIR/doio.f2.$$) WARNING: possible circular locking dependency detected ------------------------------------------------------ doio/49441 is trying to acquire lock: ffff008b7cff7290 (&(&zone->lock)->rlock){..-.}, at: rmqueue+0x138/0x2050 but task is already holding lock: 60ff000822352818 (&pool->lock/1){-.-.}, at: start_flush_work+0xd8/0x3f0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&pool->lock/1){-.-.}: lock_acquire+0x320/0x360 _raw_spin_lock+0x64/0x80 __queue_work+0x4b4/0xa10 queue_work_on+0xac/0x11c tty_schedule_flip+0x84/0xbc tty_flip_buffer_push+0x1c/0x28 pty_write+0x98/0xd0 n_tty_write+0x450/0x60c tty_write+0x338/0x474 __vfs_write+0x88/0x214 vfs_write+0x12c/0x1a4 redirected_tty_write+0x90/0xdc do_loop_readv_writev+0x140/0x180 do_iter_write+0xe0/0x10c vfs_writev+0x134/0x1cc do_writev+0xbc/0x130 __arm64_sys_writev+0x58/0x8c el0_svc_handler+0x170/0x240 el0_sync_handler+0x150/0x250 el0_sync+0x164/0x180 -> #3 (&(&port->lock)->rlock){-.-.}: lock_acquire+0x320/0x360 _raw_spin_lock_irqsave+0x7c/0x9c tty_port_tty_get+0x24/0x60 tty_port_default_wakeup+0x1c/0x3c tty_port_tty_wakeup+0x34/0x40 uart_write_wakeup+0x28/0x44 pl011_tx_chars+0x1b8/0x270 pl011_start_tx+0x24/0x70 __uart_start+0x5c/0x68 uart_write+0x164/0x1c8 do_output_char+0x33c/0x348 n_tty_write+0x4bc/0x60c tty_write+0x338/0x474 redirected_tty_write+0xc0/0xdc do_loop_readv_writev+0x140/0x180 do_iter_write+0xe0/0x10c vfs_writev+0x134/0x1cc do_writev+0xbc/0x130 __arm64_sys_writev+0x58/0x8c el0_svc_handler+0x170/0x240 el0_sync_handler+0x150/0x250 el0_sync+0x164/0x180 -> #2 (&port_lock_key){-.-.}: lock_acquire+0x320/0x360 _raw_spin_lock+0x64/0x80 pl011_console_write+0xec/0x2cc console_unlock+0x794/0x96c vprintk_emit+0x260/0x31c vprintk_default+0x54/0x7c vprintk_func+0x218/0x254 printk+0x7c/0xa4 register_console+0x734/0x7b0 uart_add_one_port+0x734/0x834 pl011_register_port+0x6c/0xac sbsa_uart_probe+0x234/0x2ec platform_drv_probe+0xd4/0x124 really_probe+0x250/0x71c driver_probe_device+0xb4/0x200 __device_attach_driver+0xd8/0x188 bus_for_each_drv+0xbc/0x110 __device_attach+0x120/0x220 device_initial_probe+0x20/0x2c bus_probe_device+0x54/0x100 device_add+0xae8/0xc2c platform_device_add+0x278/0x3b8 platform_device_register_full+0x238/0x2ac acpi_create_platform_device+0x2dc/0x3a8 acpi_bus_attach+0x390/0x3cc acpi_bus_attach+0x108/0x3cc acpi_bus_attach+0x108/0x3cc acpi_bus_attach+0x108/0x3cc acpi_bus_scan+0x7c/0xb0 acpi_scan_init+0xe4/0x304 acpi_init+0x100/0x114 do_one_initcall+0x348/0x6a0 do_initcall_level+0x190/0x1fc do_basic_setup+0x34/0x4c kernel_init_freeable+0x19c/0x260 kernel_init+0x18/0x338 ret_from_fork+0x10/0x18 -> #1 (console_owner){-...}: lock_acquire+0x320/0x360 console_lock_spinning_enable+0x6c/0x7c console_unlock+0x4f8/0x96c vprintk_emit+0x260/0x31c vprintk_default+0x54/0x7c vprintk_func+0x218/0x254 printk+0x7c/0xa4 get_random_u64+0x1c4/0x1dc shuffle_pick_tail+0x40/0xac __free_one_page+0x424/0x710 free_one_page+0x70/0x120 __free_pages_ok+0x61c/0xa94 __free_pages_core+0x1bc/0x294 memblock_free_pages+0x38/0x48 __free_pages_memory+0xcc/0xfc __free_memory_core+0x70/0x78 free_low_memory_core_early+0x148/0x18c memblock_free_all+0x18/0x54 mem_init+0xb4/0x17c mm_init+0x14/0x38 start_kernel+0x19c/0x530 -> #0 (&(&zone->lock)->rlock){..-.}: validate_chain+0xf6c/0x2e2c __lock_acquire+0x868/0xc2c lock_acquire+0x320/0x360 _raw_spin_lock+0x64/0x80 rmqueue+0x138/0x2050 get_page_from_freelist+0x474/0x688 __alloc_pages_nodemask+0x3b4/0x18dc alloc_pages_current+0xd0/0xe0 alloc_slab_page+0x2b4/0x5e0 new_slab+0xc8/0x6bc ___slab_alloc+0x3b8/0x640 kmem_cache_alloc+0x4b4/0x588 __debug_object_init+0x778/0x8b4 debug_object_init_on_stack+0x40/0x50 start_flush_work+0x16c/0x3f0 __flush_work+0xb8/0x124 flush_work+0x20/0x30 xlog_cil_force_lsn+0x88/0x204 [xfs] xfs_log_force_lsn+0x128/0x1b8 [xfs] xfs_file_fsync+0x3c4/0x488 [xfs] vfs_fsync_range+0xb0/0xd0 generic_write_sync+0x80/0xa0 [xfs] xfs_file_buffered_aio_write+0x66c/0x6e4 [xfs] xfs_file_write_iter+0x1a0/0x218 [xfs] __vfs_write+0x1cc/0x214 vfs_write+0x12c/0x1a4 ksys_write+0xb0/0x120 __arm64_sys_write+0x54/0x88 el0_svc_handler+0x170/0x240 el0_sync_handler+0x150/0x250 el0_sync+0x164/0x180 other info that might help us debug this: Chain exists of: &(&zone->lock)->rlock --> &(&port->lock)->rlock --> &pool->lock/1 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pool->lock/1); lock(&(&port->lock)->rlock); lock(&pool->lock/1); lock(&(&zone->lock)->rlock); *** DEADLOCK *** 4 locks held by doio/49441: #0: a0ff00886fc27408 (sb_writers#8){.+.+}, at: vfs_write+0x118/0x1a4 #1: 8fff00080810dfe0 (&xfs_nondir_ilock_class){++++}, at: xfs_ilock+0x2a8/0x300 [xfs] #2: ffff9000129f2390 (rcu_read_lock){....}, at: rcu_lock_acquire+0x8/0x38 #3: 60ff000822352818 (&pool->lock/1){-.-.}, at: start_flush_work+0xd8/0x3f0 stack backtrace: CPU: 48 PID: 49441 Comm: doio Tainted: G W Hardware name: HPE Apollo 70 /C01_APACHE_MB , BIOS L50_5.13_1.11 06/18/2019 Call trace: dump_backtrace+0x0/0x248 show_stack+0x20/0x2c dump_stack+0xe8/0x150 print_circular_bug+0x368/0x380 check_noncircular+0x28c/0x294 validate_chain+0xf6c/0x2e2c __lock_acquire+0x868/0xc2c lock_acquire+0x320/0x360 _raw_spin_lock+0x64/0x80 rmqueue+0x138/0x2050 get_page_from_freelist+0x474/0x688 __alloc_pages_nodemask+0x3b4/0x18dc alloc_pages_current+0xd0/0xe0 alloc_slab_page+0x2b4/0x5e0 new_slab+0xc8/0x6bc ___slab_alloc+0x3b8/0x640 kmem_cache_alloc+0x4b4/0x588 __debug_object_init+0x778/0x8b4 debug_object_init_on_stack+0x40/0x50 start_flush_work+0x16c/0x3f0 __flush_work+0xb8/0x124 flush_work+0x20/0x30 xlog_cil_force_lsn+0x88/0x204 [xfs] xfs_log_force_lsn+0x128/0x1b8 [xfs] xfs_file_fsync+0x3c4/0x488 [xfs] vfs_fsync_range+0xb0/0xd0 generic_write_sync+0x80/0xa0 [xfs] xfs_file_buffered_aio_write+0x66c/0x6e4 [xfs] xfs_file_write_iter+0x1a0/0x218 [xfs] __vfs_write+0x1cc/0x214 vfs_write+0x12c/0x1a4 ksys_write+0xb0/0x120 __arm64_sys_write+0x54/0x88 el0_svc_handler+0x170/0x240 el0_sync_handler+0x150/0x250 el0_sync+0x164/0x180 Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Signed-off-by: Qian Cai <cai@lca.pw> Link: https://lore.kernel.org/r/1573679785-21068-1-git-send-email-cai@lca.pw Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-05-31random: add a spinlock_t to struct batched_entropySebastian Andrzej Siewior1-25/+27
[ Upstream commit b7d5dc21072cda7124d13eae2aefb7343ef94197 ] The per-CPU variable batched_entropy_uXX is protected by get_cpu_var(). This is just a preempt_disable() which ensures that the variable is only from the local CPU. It does not protect against users on the same CPU from another context. It is possible that a preemptible context reads slot 0 and then an interrupt occurs and the same value is read again. The above scenario is confirmed by lockdep if we add a spinlock: | ================================ | WARNING: inconsistent lock state | 5.1.0-rc3+ #42 Not tainted | -------------------------------- | inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. | ksoftirqd/9/56 [HC0[0]:SC1[1]:HE0:SE0] takes: | (____ptrval____) (batched_entropy_u32.lock){+.?.}, at: get_random_u32+0x3e/0xe0 | {SOFTIRQ-ON-W} state was registered at: | _raw_spin_lock+0x2a/0x40 | get_random_u32+0x3e/0xe0 | new_slab+0x15c/0x7b0 | ___slab_alloc+0x492/0x620 | __slab_alloc.isra.73+0x53/0xa0 | kmem_cache_alloc_node+0xaf/0x2a0 | copy_process.part.41+0x1e1/0x2370 | _do_fork+0xdb/0x6d0 | kernel_thread+0x20/0x30 | kthreadd+0x1ba/0x220 | ret_from_fork+0x3a/0x50 … | other info that might help us debug this: | Possible unsafe locking scenario: | | CPU0 | ---- | lock(batched_entropy_u32.lock); | <Interrupt> | lock(batched_entropy_u32.lock); | | *** DEADLOCK *** | | stack backtrace: | Call Trace: … | kmem_cache_alloc_trace+0x20e/0x270 | ipmi_alloc_recv_msg+0x16/0x40 … | __do_softirq+0xec/0x48d | run_ksoftirqd+0x37/0x60 | smpboot_thread_fn+0x191/0x290 | kthread+0xfe/0x130 | ret_from_fork+0x3a/0x50 Add a spinlock_t to the batched_entropy data structure and acquire the lock while accessing it. Acquire the lock with disabled interrupts because this function may be used from interrupt context. Remove the batched_entropy_reset_lock lock. Now that we have a lock for the data scructure, we can access it from a remote CPU. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Sasha Levin <sashal@kernel.org>
2018-08-03random: mix rdrand with entropy sent in from userspaceTheodore Ts'o1-1/+9
commit 81e69df38e2911b642ec121dec319fad2a4782f3 upstream. Fedora has integrated the jitter entropy daemon to work around slow boot problems, especially on VM's that don't support virtio-rng: https://bugzilla.redhat.com/show_bug.cgi?id=1572944 It's understandable why they did this, but the Jitter entropy daemon works fundamentally on the principle: "the CPU microarchitecture is **so** complicated and we can't figure it out, so it *must* be random". Yes, it uses statistical tests to "prove" it is secure, but AES_ENCRYPT(NSA_KEY, COUNTER++) will also pass statistical tests with flying colors. So if RDRAND is available, mix it into entropy submitted from userspace. It can't hurt, and if you believe the NSA has backdoored RDRAND, then they probably have enough details about the Intel microarchitecture that they can reverse engineer how the Jitter entropy daemon affects the microarchitecture, and attack its output stream. And if RDRAND is in fact an honest DRNG, it will immeasurably improve on what the Jitter entropy daemon might produce. This also provides some protection against someone who is able to read or set the entropy seed file. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-01random: rate limit unseeded randomness warningsTheodore Ts'o1-5/+34
commit 4e00b339e264802851aff8e73cde7d24b57b18ce upstream. On systems without sufficient boot randomness, no point spamming dmesg. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-01random: fix possible sleeping allocation from irq contextTheodore Ts'o1-1/+8
commit 6c1e851c4edc13a43adb3ea4044e3fc8f43ccf7d upstream. We can do a sleeping allocation from an irq context when CONFIG_NUMA is enabled. Fix this by initializing the NUMA crng instances in a workqueue. Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot+9de458f6a5e713ee8c1a@syzkaller.appspotmail.com Fixes: 8ef35c866f8862df ("random: set up the NUMA crng instances...") Cc: stable@vger.kernel.org Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-01random: set up the NUMA crng instances after the CRNG is fully initializedTheodore Ts'o1-19/+27
commit 8ef35c866f8862df074a49a93b0309725812dea8 upstream. Until the primary_crng is fully initialized, don't initialize the NUMA crng nodes. Otherwise users of /dev/urandom on NUMA systems before the CRNG is fully initialized can get very bad quality randomness. Of course everyone should move to getrandom(2) where this won't be an issue, but there's a lot of legacy code out there. This related to CVE-2018-1108. Reported-by: Jann Horn <jannh@google.com> Fixes: 1e7f583af67b ("random: make /dev/urandom scalable for silly...") Cc: stable@kernel.org # 4.8+ Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-24random: add new ioctl RNDRESEEDCRNGTheodore Ts'o1-1/+12
commit d848e5f8e1ebdb227d045db55fe4f825e82965fa upstream. Add a new ioctl which forces the the crng to be reseeded. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-24random: crng_reseed() should lock the crng instance that it is modifyingTheodore Ts'o1-2/+2
commit 0bb29a849a6433b72e249eea7695477b02056e94 upstream. Reported-by: Jann Horn <jannh@google.com> Fixes: 1e7f583af67b ("random: make /dev/urandom scalable for silly...") Cc: stable@kernel.org # 4.8+ Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jann Horn <jannh@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-24random: use a different mixing algorithm for add_device_randomness()Theodore Ts'o1-4/+51
commit dc12baacb95f205948f64dc936a47d89ee110117 upstream. add_device_randomness() use of crng_fast_load() was highly problematic. Some callers of add_device_randomness() can pass in a large amount of static information. This would immediately promote the crng_init state from 0 to 1, without really doing much to initialize the primary_crng's internal state with something even vaguely unpredictable. Since we don't have the speed constraints of add_interrupt_randomness(), we can do a better job mixing in the what unpredictability a device driver or architecture maintainer might see fit to give us, and do it in a way which does not bump the crng_init_cnt variable. Also, since add_device_randomness() doesn't bump any entropy accounting in crng_init state 0, mix the device randomness into the input_pool entropy pool as well. This is related to CVE-2018-1108. Reported-by: Jann Horn <jannh@google.com> Fixes: ee7998c50c26 ("random: do not ignore early device randomness") Cc: stable@kernel.org # 4.13+ Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-24random: fix crng_ready() testTheodore Ts'o1-5/+5
commit 43838a23a05fbd13e47d750d3dfd77001536dd33 upstream. The crng_init variable has three states: 0: The CRNG is not initialized at all 1: The CRNG has a small amount of entropy, hopefully good enough for early-boot, non-cryptographical use cases 2: The CRNG is fully initialized and we are sure it is safe for cryptographic use cases. The crng_ready() function should only return true once we are in the last state. This addresses CVE-2018-1108. Reported-by: Jann Horn <jannh@google.com> Fixes: e192be9d9a30 ("random: replace non-blocking pool...") Cc: stable@kernel.org # 4.8+ Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jann Horn <jannh@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-24random: use a tighter cap in credit_entropy_bits_safe()Theodore Ts'o1-1/+1
commit 9f886f4d1d292442b2f22a0a33321eae821bde40 upstream. This fixes a harmless UBSAN where root could potentially end up causing an overflow while bumping the entropy_total field (which is ignored once the entropy pool has been initialized, and this generally is completed during the boot sequence). This is marginal for the stable kernel series, but it's a really trivial patch, and it fixes UBSAN warning that might cause security folks to get overly excited for no reason. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reported-by: Chen Feng <puck.chen@hisilicon.com> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-02-22kmemcheck: remove annotationsLevin, Alexander (Sasha Levin)1-1/+0
commit 4950276672fce5c241857540f8561c440663673d upstream. Patch series "kmemcheck: kill kmemcheck", v2. As discussed at LSF/MM, kill kmemcheck. KASan is a replacement that is able to work without the limitation of kmemcheck (single CPU, slow). KASan is already upstream. We are also not aware of any users of kmemcheck (or users who don't consider KASan as a suitable replacement). The only objection was that since KASAN wasn't supported by all GCC versions provided by distros at that time we should hold off for 2 years, and try again. Now that 2 years have passed, and all distros provide gcc that supports KASAN, kill kmemcheck again for the very same reasons. This patch (of 4): Remove kmemcheck annotations, and calls to kmemcheck from the kernel. [alexander.levin@verizon.com: correctly remove kmemcheck call from dma_map_sg_attrs] Link: http://lkml.kernel.org/r/20171012192151.26531-1-alexander.levin@verizon.com Link: http://lkml.kernel.org/r/20171007030159.22241-2-alexander.levin@verizon.com Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Cc: Alexander Potapenko <glider@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tim Hansen <devtimhansen@gmail.com> Cc: Vegard Nossum <vegardno@ifi.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-08-08random: fix warning message on ia64 and pariscHelge Deller1-1/+1
Fix the warning message on the parisc and IA64 architectures to show the correct function name of the caller by using %pS instead of %pF. The message is printed with the value of _RET_IP_ which calls __builtin_return_address(0) and as such returns the IP address caller instead of pointer to a function descriptor of the caller. The effect of this patch is visible on the parisc and ia64 architectures only since those are the ones which use function descriptors while on all others %pS and %pF will behave the same. Cc: Theodore Ts'o <tytso@mit.edu> Cc: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Helge Deller <deller@gmx.de> Fixes: eecabf567422 ("random: suppress spammy warnings about unseeded randomness") Fixes: d06bfd1989fe ("random: warn when kernel uses unseeded randomness") Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-15Merge tag 'random_for_linus' of ↵Linus Torvalds1-20/+76
git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random Pull random updates from Ted Ts'o: "Add wait_for_random_bytes() and get_random_*_wait() functions so that callers can more safely get random bytes if they can block until the CRNG is initialized. Also print a warning if get_random_*() is called before the CRNG is initialized. By default, only one single-line warning will be printed per boot. If CONFIG_WARN_ALL_UNSEEDED_RANDOM is defined, then a warning will be printed for each function which tries to get random bytes before the CRNG is initialized. This can get spammy for certain architecture types, so it is not enabled by default" * tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random: random: reorder READ_ONCE() in get_random_uXX random: suppress spammy warnings about unseeded randomness random: warn when kernel uses unseeded randomness net/route: use get_random_int for random counter net/neighbor: use get_random_u32 for 32-bit hash random rhashtable: use get_random_u32 for hash_rnd ceph: ensure RNG is seeded before using iscsi: ensure RNG is seeded before use cifs: use get_random_u32 for 32-bit lock random random: add get_random_{bytes,u32,u64,int,long,once}_wait family random: add wait_for_random_bytes() API
2017-07-15random: reorder READ_ONCE() in get_random_uXXSebastian Andrzej Siewior1-2/+4
Avoid the READ_ONCE in commit 4a072c71f49b ("random: silence compiler warnings and fix race") if we can leave the function after arch_get_random_XXX(). Cc: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-07-15random: suppress spammy warnings about unseeded randomnessTheodore Ts'o1-17/+39
Unfortunately, on some models of some architectures getting a fully seeded CRNG is extremely difficult, and so this can result in dmesg getting spammed for a surprisingly long time. This is really bad from a security perspective, and so architecture maintainers really need to do what they can to get the CRNG seeded sooner after the system is booted. However, users can't do anything actionble to address this, and spamming the kernel messages log will only just annoy people. For developers who want to work on improving this situation, CONFIG_WARN_UNSEEDED_RANDOM has been renamed to CONFIG_WARN_ALL_UNSEEDED_RANDOM. By default the kernel will always print the first use of unseeded randomness. This way, hopefully the security obsessed will be happy that there is _some_ indication when the kernel boots there may be a potential issue with that architecture or subarchitecture. To see all uses of unseeded randomness, developers can enable CONFIG_WARN_ALL_UNSEEDED_RANDOM. Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-07-13random: do not ignore early device randomnessKees Cook1-0/+5
The add_device_randomness() function would ignore incoming bytes if the crng wasn't ready. This additionally makes sure to make an early enough call to add_latent_entropy() to influence the initial stack canary, which is especially important on non-x86 systems where it stays the same through the life of the boot. Link: http://lkml.kernel.org/r/20170626233038.GA48751@beast Signed-off-by: Kees Cook <keescook@chromium.org> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jessica Yu <jeyu@redhat.com> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Tejun Heo <tj@kernel.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Lokesh Vutla <lokeshvutla@ti.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: AKASHI Takahiro <takahiro.akashi@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-20random: warn when kernel uses unseeded randomnessJason A. Donenfeld1-2/+13
This enables an important dmesg notification about when drivers have used the crng without it being seeded first. Prior, these errors would occur silently, and so there hasn't been a great way of diagnosing these types of bugs for obscure setups. By adding this as a config option, we can leave it on by default, so that we learn where these issues happen, in the field, will still allowing some people to turn it off, if they really know what they're doing and do not want the log entries. However, we don't leave it _completely_ by default. An earlier version of this patch simply had `default y`. I'd really love that, but it turns out, this problem with unseeded randomness being used is really quite present and is going to take a long time to fix. Thus, as a compromise between log-messages-for-all and nobody-knows, this is `default y`, except it is also `depends on DEBUG_KERNEL`. This will ensure that the curious see the messages while others don't have to. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-06-20random: add wait_for_random_bytes() APIJason A. Donenfeld1-10/+31
This enables users of get_random_{bytes,u32,u64,int,long} to wait until the pool is ready before using this function, in case they actually want to have reliable randomness. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-06-20random: silence compiler warnings and fix raceJason A. Donenfeld1-6/+6
Odd versions of gcc for the sh4 architecture will actually warn about flags being used while uninitialized, so we set them to zero. Non crazy gccs will optimize that out again, so it doesn't make a difference. Next, over aggressive gccs could inline the expression that defines use_lock, which could then introduce a race resulting in a lock imbalance. By using READ_ONCE, we prevent that fate. Finally, we make that assignment const, so that gcc can still optimize a nice amount. Finally, we fix a potential deadlock between primary_crng.lock and batched_entropy_reset_lock, where they could be called in opposite order. Moving the call to invalidate_batched_entropy to outside the lock rectifies this issue. Fixes: b169c13de473a85b3c859bb36216a4cb5f00a54a Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org
2017-06-08random: invalidate batched entropy after crng initJason A. Donenfeld1-0/+37
It's possible that get_random_{u32,u64} is used before the crng has initialized, in which case, its output might not be cryptographically secure. For this problem, directly, this patch set is introducing the *_wait variety of functions, but even with that, there's a subtle issue: what happens to our batched entropy that was generated before initialization. Prior to this commit, it'd stick around, supplying bad numbers. After this commit, we force the entropy to be re-extracted after each phase of the crng has initialized. In order to avoid a race condition with the position counter, we introduce a simple rwlock for this invalidation. Since it's only during this awkward transition period, after things are all set up, we stop using it, so that it doesn't have an impact on performance. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org # v4.11+
2017-06-08random: use lockless method of accessing and updating f->reg_idxTheodore Ts'o1-6/+6
Linus pointed out that there is a much more efficient way of avoiding the problem that we were trying to address in commit 9dfa7bba35ac0: "fix race in drivers/char/random.c:get_reg()". Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-05-25fix race in drivers/char/random.c:get_reg()Michael Schmitz1-1/+5
get_reg() can be reentered on architectures with prioritized interrupts (m68k in this case), causing f->reg_index to be incremented after the range check. Out of bounds memory access past the pt_regs struct results. This will go mostly undetected unless access is beyond end of memory. Prevent the race by disabling interrupts in get_reg(). Tested on m68k (Atari Falcon, and ARAnyM emulator). Kudos to Geert Uytterhoeven for helping to trace this race. Signed-off-by: Michael Schmitz <schmitzmic@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-02-07random: move random_min_urandom_seed into CONFIG_SYSCTL ifdef blockFabio Estevam1-5/+1
Building arm allnodefconfig causes the following build warning: drivers/char/random.c:318:12: warning: 'random_min_urandom_seed' defined but not used [-Wunused-variable] Fix the warning by moving 'random_min_urandom_seed' declaration inside the CONFIG_SYSCTL ifdef block, where it is actually used. While at it, remove the comment prior to the variable declaration. Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-01-27random: convert get_random_int/long into get_random_u32/u64Jason A. Donenfeld1-28/+27
Many times, when a user wants a random number, he wants a random number of a guaranteed size. So, thinking of get_random_int and get_random_long in terms of get_random_u32 and get_random_u64 makes it much easier to achieve this. It also makes the code simpler. On 32-bit platforms, get_random_int and get_random_long are both aliased to get_random_u32. On 64-bit platforms, int->u32 and long->u64. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-01-27random: use chacha20 for get_random_int/longJason A. Donenfeld1-41/+43
Now that our crng uses chacha20, we can rely on its speedy characteristics for replacing MD5, while simultaneously achieving a higher security guarantee. Before the idea was to use these functions if you wanted random integers that aren't stupidly insecure but aren't necessarily secure either, a vague gray zone, that hopefully was "good enough" for its users. With chacha20, we can strengthen this claim, since either we're using an rdrand-like instruction, or we're using the same crng as /dev/urandom. And it's faster than what was before. We could have chosen to replace this with a SipHash-derived function, which might be slightly faster, but at the cost of having yet another RNG construction in the kernel. By moving to chacha20, we have a single RNG to analyze and verify, and we also already get good performance improvements on all platforms. Implementation-wise, rather than use a generic buffer for both get_random_int/long and memcpy based on the size needs, we use a specific buffer for 32-bit reads and for 64-bit reads. This way, we're guaranteed to always have aligned accesses on all platforms. While slightly more verbose in C, the assembly this generates is a lot simpler than otherwise. Finally, on 32-bit platforms where longs and ints are the same size, we simply alias get_random_int to get_random_long. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Suggested-by: Theodore Ts'o <tytso@mit.edu> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> Cc: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-01-19random: fix comment for unused random_min_urandom_seedStephan Müller1-3/+1
The variable random_min_urandom_seed is not needed any more as it defined the reseeding behavior of the nonblocking pool. Though it is not needed any more, it is left in the code for user space interface compatibility. Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-01-19random: remove variable limitStephan Müller1-23/+7
The variable limit was used to identify the nonblocking pool's unlimited random number generation. As the nonblocking pool is a thing of the past, remove the limit variable and any conditions around it (i.e. preserve the branches for limit == 1). Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-01-19random: remove stale urandom_init_waitStephan Müller1-1/+0
The urandom_init_wait wait queue is a left over from the pre-ChaCha20 times and can therefore be savely removed. Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-01-19random: remove stale maybe_reseed_primary_crngStephan Mueller1-7/+0
The function maybe_reseed_primary_crng is not used anywhere and thus can be removed. Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-12-24Replace <asm/uaccess.h> with <linux/uaccess.h> globallyLinus Torvalds1-1/+1
This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>' sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-15Merge tag 'gcc-plugins-v4.9-rc1' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull gcc plugins update from Kees Cook: "This adds a new gcc plugin named "latent_entropy". It is designed to extract as much possible uncertainty from a running system at boot time as possible, hoping to capitalize on any possible variation in CPU operation (due to runtime data differences, hardware differences, SMP ordering, thermal timing variation, cache behavior, etc). At the very least, this plugin is a much more comprehensive example for how to manipulate kernel code using the gcc plugin internals" * tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: latent_entropy: Mark functions with __latent_entropy gcc-plugins: Add latent_entropy plugin
2016-10-12random: remove unused randomize_range()Jason Cooper1-19/+0
All call sites for randomize_range have been updated to use the much simpler and more robust randomize_addr(). Remove the now unnecessary code. Link: http://lkml.kernel.org/r/20160803233913.32511-8-jason@lakedaemon.net Signed-off-by: Jason Cooper <jason@lakedaemon.net> Acked-by: Kees Cook <keescook@chromium.org> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-12random: simplify API for random address requestsJason Cooper1-0/+33
To date, all callers of randomize_range() have set the length to 0, and check for a zero return value. For the current callers, the only way to get zero returned is if end <= start. Since they are all adding a constant to the start address, this is unnecessary. We can remove a bunch of needless checks by simplifying the API to do just what everyone wants, return an address between [start, start + range). While we're here, s/get_random_int/get_random_long/. No current call site is adversely affected by get_random_int(), since all current range requests are < UINT_MAX. However, we should match caller expectations to avoid coming up short (ha!) in the future. All current callers to randomize_range() chose to use the start address if randomize_range() failed. Therefore, we simplify things by just returning the start address on error. randomize_range() will be removed once all callers have been converted over to randomize_addr(). Link: http://lkml.kernel.org/r/20160803233913.32511-2-jason@lakedaemon.net Signed-off-by: Jason Cooper <jason@lakedaemon.net> Acked-by: Kees Cook <keescook@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Roberts, William C" <william.c.roberts@intel.com> Cc: Yann Droneaud <ydroneaud@opteya.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: Nick Kralevich <nnk@google.com> Cc: Jeffrey Vander Stoep <jeffv@google.com> Cc: Daniel Cashman <dcashman@android.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11latent_entropy: Mark functions with __latent_entropyEmese Revfy1-2/+2
The __latent_entropy gcc attribute can be used only on functions and variables. If it is on a function then the plugin will instrument it for gathering control-flow entropy. If the attribute is on a variable then the plugin will initialize it with random contents. The variable must be an integer, an integer array type or a structure with integer fields. These specific functions have been selected because they are init functions (to help gather boot-time entropy), are called at unpredictable times, or they have variable loops, each of which provide some level of latent entropy. Signed-off-by: Emese Revfy <re.emese@gmail.com> [kees: expanded commit message] Signed-off-by: Kees Cook <keescook@chromium.org>
2016-07-31random: Fix crashes with sparse node idsMichael Ellerman1-3/+2
On a system with sparse node ids, eg. a powerpc system with 4 nodes numbered like so: node 0: [mem 0x0000000000000000-0x00000007ffffffff] node 1: [mem 0x0000000800000000-0x0000000fffffffff] node 16: [mem 0x0000001000000000-0x00000017ffffffff] node 17: [mem 0x0000001800000000-0x0000001fffffffff] The code in rand_initialize() will allocate 4 pointers for the pool array, and initialise them correctly. However when go to use the pool, in eg. extract_crng(), we use the numa_node_id() to index into the array. For the higher numbered node ids this leads to random memory corruption, depending on what was kmalloc'ed adjacent to the pool array. Fix it by using nr_node_ids to size the pool array. Fixes: 1e7f583af67b ("random: make /dev/urandom scalable for silly userspace programs") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-28random: use for_each_online_node() to iterate over NUMA nodesTheodore Ts'o1-2/+1
This fixes a crash on s390 with fake NUMA enabled. Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com> Fixes: 1e7f583af67b ("random: make /dev/urandom scalable for silly userspace programs") Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-07-04random: strengthen input validation for RNDADDTOENTCNTTheodore Ts'o1-6/+7
Don't allow RNDADDTOENTCNT or RNDADDENTROPY to accept a negative entropy value. It doesn't make any sense to subtract from the entropy counter, and it can trigger a warning: random: negative entropy/overflow: pool input count -40000 ------------[ cut here ]------------ WARNING: CPU: 3 PID: 6828 at drivers/char/random.c:670[< none >] credit_entropy_bits+0x21e/0xad0 drivers/char/random.c:670 Modules linked in: CPU: 3 PID: 6828 Comm: a.out Not tainted 4.7.0-rc4+ #4 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffffffff880b58e0 ffff88005dd9fcb0 ffffffff82cc838f ffffffff87158b40 fffffbfff1016b1c 0000000000000000 0000000000000000 ffffffff87158b40 ffffffff83283dae 0000000000000009 ffff88005dd9fcf8 ffffffff8136d27f Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [<ffffffff82cc838f>] dump_stack+0x12e/0x18f lib/dump_stack.c:51 [<ffffffff8136d27f>] __warn+0x19f/0x1e0 kernel/panic.c:516 [<ffffffff8136d48c>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:551 [<ffffffff83283dae>] credit_entropy_bits+0x21e/0xad0 drivers/char/random.c:670 [< inline >] credit_entropy_bits_safe drivers/char/random.c:734 [<ffffffff8328785d>] random_ioctl+0x21d/0x250 drivers/char/random.c:1546 [< inline >] vfs_ioctl fs/ioctl.c:43 [<ffffffff8185316c>] do_vfs_ioctl+0x18c/0xff0 fs/ioctl.c:674 [< inline >] SYSC_ioctl fs/ioctl.c:689 [<ffffffff8185405f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:680 [<ffffffff86a995c0>] entry_SYSCALL_64_fastpath+0x23/0xc1 arch/x86/entry/entry_64.S:207 ---[ end trace 5d4902b2ba842f1f ]--- This was triggered using the test program: // autogenerated by syzkaller (http://github.com/google/syzkaller) int main() { int fd = open("/dev/random", O_RDWR); int val = -5000; ioctl(fd, RNDADDTOENTCNT, &val); return 0; } It's harmless in that (a) only root can trigger it, and (b) after complaining the code never does let the entropy count go negative, but it's better to simply not allow this userspace from passing in a negative entropy value altogether. Google-Bug-Id: #29575089 Reported-By: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-07-03random: add backtracking protection to the CRNGTheodore Ts'o1-5/+49
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-07-03random: make /dev/urandom scalable for silly userspace programsTheodore Ts'o1-4/+58
On a system with a 4 socket (NUMA) system where a large number of application threads were all trying to read from /dev/urandom, this can result in the system spending 80% of its time contending on the global urandom spinlock. The application should have used its own PRNG, but let's try to help it from running, lemming-like, straight over the locking cliff. Reported-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-07-03random: replace non-blocking pool with a Chacha20-based CRNGTheodore Ts'o1-102/+276
The CRNG is faster, and we don't pretend to track entropy usage in the CRNG any more. Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-06-13random: properly align get_random_int_hashEric Biggers1-1/+3
get_random_long() reads from the get_random_int_hash array using an unsigned long pointer. For this code to be guaranteed correct on all architectures, the array must be aligned to an unsigned long boundary. Cc: stable@kernel.org Signed-off-by: Eric Biggers <ebiggers3@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-06-13random: add interrupt callback to VMBus IRQ handlerStephan Mueller1-0/+1
The Hyper-V Linux Integration Services use the VMBus implementation for communication with the Hypervisor. VMBus registers its own interrupt handler that completely bypasses the common Linux interrupt handling. This implies that the interrupt entropy collector is not triggered. This patch adds the interrupt entropy collection callback into the VMBus interrupt handler function. Cc: stable@kernel.org Signed-off-by: Stephan Mueller <stephan.mueller@atsec.com> Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-06-13random: print a warning for the first ten uninitialized random usersTheodore Ts'o1-4/+8
Since systemd is consistently using /dev/urandom before it is initialized, we can't see the other potentially dangerous users of /dev/urandom immediately after boot. So print the first ten such complaints instead. Cc: stable@kernel.org Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-06-13random: initialize the non-blocking pool via add_hwgenerator_randomness()Theodore Ts'o1-5/+11
If we have a hardware RNG and are using the in-kernel rngd, we should use this to initialize the non-blocking pool so that getrandom(2) doesn't block unnecessarily. Cc: stable@kernel.org Signed-off-by: Theodore Ts'o <tytso@mit.edu>
generated by cgit v1.2.3 (git 2.39.0) at 2025-08-31 20:26:57 +0300