kernel/linux.git/init/Kconfig, branch v4.9.131

bpf: introduce BPF_JIT_ALWAYS_ON config

2018-01-31T11:55:56+00:00

[ upstream commit 290af86629b25ffd1ed6232c4e9107da031705cb ] The BPF interpreter has been used as part of the spectre 2 attack CVE-2017-5715. A quote from goolge project zero blog: "At this point, it would normally be necessary to locate gadgets in the host kernel code that can be used to actually leak data by reading from an attacker-controlled location, shifting and masking the result appropriately and then using the result of that as offset to an attacker-controlled address for a load. But piecing gadgets together and figuring out which ones work in a speculation context seems annoying. So instead, we decided to use the eBPF interpreter, which is built into the host kernel - while there is no legitimate way to invoke it from inside a VM, the presence of the code in the host kernel's text section is sufficient to make it usable for the attack, just like with ordinary ROP gadgets." To make attacker job harder introduce BPF_JIT_ALWAYS_ON config option that removes interpreter from the kernel in favor of JIT-only mode. So far eBPF JIT is supported by: x64, arm64, arm32, sparc64, s390, powerpc64, mips64 The start of JITed program is randomized and code page is marked as read-only. In addition "constant blinding" can be turned on with net.core.bpf_jit_harden v2->v3: - move __bpf_prog_ret0 under ifdef (Daniel) v1->v2: - fix init order, test_bpf and cBPF (Daniel's feedback) - fix offloaded bpf (Jakub's feedback) - add 'return 0' dummy in case something can invoke prog->bpf_func - retarget bpf tree. For bpf-next the patch would need one extra hunk. It will be sent when the trees are merged back to net-next Considered doing: int bpf_jit_enable __read_mostly = BPF_EBPF_JIT_DEFAULT; but it seems better to land the patch as-is and in bpf-next remove bpf_jit_enable global variable from all JITs, consolidate in one place and remove this jit_init() function. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Signed-off-by: Greg Kroah-Hartman

Re-enable CONFIG_MODVERSIONS in a slightly weaker form

2016-11-30T00:01:30+00:00

This enables CONFIG_MODVERSIONS again, but allows for missing symbol CRC information in order to work around the issue that newer binutils versions seem to occasionally drop the CRC on the floor. binutils 2.26 seems to work fine, while binutils 2.27 seems to break MODVERSIONS of symbols that have been defined in assembler files. [ We've had random missing CRC's before - it may be an old problem that just is now reliably triggered with the weak asm symbols and a new version of binutils ] Some day I really do want to remove MODVERSIONS entirely. Sadly, today does not appear to be that day: Debian people apparently do want the option to enable MODVERSIONS to make it easier to have external modules across kernel versions, and this seems to be a fairly minimal fix for the annoying problem. Cc: Ben Hutchings Acked-by: Michal Marek Signed-off-by: Linus Torvalds

Fix subtle CONFIG_MODVERSIONS problems

2016-11-25T23:44:47+00:00

CONFIG_MODVERSIONS has been broken for pretty much the whole 4.9 series, and quite frankly, nobody has cared very deeply. We absolutely know how to fix it, and it's not _complicated_, but it's not exactly pretty either. This oneliner fixes it without the ugliness, and allows for further future cleanups. "We've secretly replaced their regular MODVERSIONS with nothing at all, let's see if they notice" Signed-off-by: Linus Torvalds

relay: Use irq_work instead of plain timer for deferred wakeup

2016-10-11T22:06:32+00:00

Relay avoids calling wake_up_interruptible() for doing the wakeup of readers/consumers, waiting for the generation of new data, from the context of a process which produced the data. This is apparently done to prevent the possibility of a deadlock in case Scheduler itself is is generating data for the relay, after acquiring rq->lock. The following patch used a timer (to be scheduled at next jiffy), for delegating the wakeup to another context. commit 7c9cb38302e78d24e37f7d8a2ea7eed4ae5f2fa7 Author: Tom Zanussi Date: Wed May 9 02:34:01 2007 -0700 relay: use plain timer instead of delayed work relay doesn't need to use schedule_delayed_work() for waking readers when a simple timer will do. Scheduling a plain timer, at next jiffies boundary, to do the wakeup causes a significant wakeup latency for the Userspace client, which makes relay less suitable for the high-frequency low-payload use cases where the data gets generated at a very high rate, like multiple sub buffers getting filled within a milli second. Moreover the timer is re-scheduled on every newly produced sub buffer so the timer keeps getting pushed out if sub buffers are filled in a very quick succession (less than a jiffy gap between filling of 2 sub buffers). As a result relay runs out of sub buffers to store the new data. By using irq_work it is ensured that wakeup of userspace client, blocked in the poll call, is done at earliest (through self IPI or next timer tick) enabling it to always consume the data in time. Also this makes relay consistent with printk & ring buffers (trace), as they too use irq_work for deferred wake up of readers. [arnd@arndb.de: select CONFIG_IRQ_WORK] Link: http://lkml.kernel.org/r/20160912154035.3222156-1-arnd@arndb.de [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1472906487-1559-1-git-send-email-akash.goel@intel.com Signed-off-by: Peter Zijlstra Signed-off-by: Akash Goel Cc: Tom Zanussi Cc: Chris Wilson Cc: Tvrtko Ursulin Signed-off-by: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'parisc-4.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux

2016-10-08T03:50:37+00:00

Pull parisc updates from Helge Deller: "Changes include: - Fix boot of 32bit SMP kernel (initial kernel mapping was too small) - Added hardened usercopy checks - Drop bootmem and switch to memblock and NO_BOOTMEM implementation - Drop the BROKEN_RODATA config option (and thus remove the relevant code from the generic headers and files because parisc was the last architecture which used this config option) - Improve segfault reporting by printing human readable error strings - Various smaller changes, e.g. dwarf debug support for assembly code, update comments regarding copy_user_page_asm, switch to kmalloc_array()" * 'parisc-4.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: parisc: Increase KERNEL_INITIAL_SIZE for 32-bit SMP kernels parisc: Drop bootmem and switch to memblock parisc: Add hardened usercopy feature parisc: Add cfi_startproc and cfi_endproc to assembly code parisc: Move hpmc stack into page aligned bss section parisc: Fix self-detected CPU stall warnings on Mako machines parisc: Report trap type as human readable string parisc: Update comment regarding implementation of copy_user_page_asm parisc: Use kmalloc_array() in add_system_map_addresses() parisc: Check return value of smp_boot_one_cpu() parisc: Drop BROKEN_RODATA config option

parisc: Drop BROKEN_RODATA config option

2016-09-20T16:02:35+00:00

PARISC was the only architecture which selected the BROKEN_RODATA config option. Drop it and remove the special handling from init.h as well. Signed-off-by: Helge Deller

sched/core: Add try_get_task_stack() and put_task_stack()

2016-09-16T07:18:53+00:00

There are a few places in the kernel that access stack memory belonging to a different task. Before we can start freeing task stacks before the task_struct is freed, we need a way for those code paths to pin the stack. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/17a434f50ad3d77000104f21666575e10a9c1fbd.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar

sched/core: Allow putting thread_info into task_struct

2016-09-15T06:25:13+00:00

If an arch opts in by setting CONFIG_THREAD_INFO_IN_TASK_STRUCT, then thread_info is defined as a single 'u32 flags' and is the first entry of task_struct. thread_info::task is removed (it serves no purpose if thread_info is embedded in task_struct), and thread_info::cpu gets its own slot in task_struct. This is heavily based on a patch written by Linus. Originally-from: Linus Torvalds Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/a0898196f0476195ca02713691a5037a14f2aac5.1473801993.git.luto@kernel.org Signed-off-by: Ingo Molnar

Merge tag 'usercopy-v4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2016-08-08T21:48:14+00:00

Pull usercopy protection from Kees Cook: "Tbhis implements HARDENED_USERCOPY verification of copy_to_user and copy_from_user bounds checking for most architectures on SLAB and SLUB" * tag 'usercopy-v4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: mm: SLUB hardened usercopy support mm: SLAB hardened usercopy support s390/uaccess: Enable hardened usercopy sparc/uaccess: Enable hardened usercopy powerpc/uaccess: Enable hardened usercopy ia64/uaccess: Enable hardened usercopy arm64/uaccess: Enable hardened usercopy ARM: uaccess: Enable hardened usercopy x86/uaccess: Enable hardened usercopy mm: Hardened usercopy mm: Implement stack frame object validation mm: Add is_migrate_cma_page

init/Kconfig: add clarification for out-of-tree modules

2016-08-02T23:35:43+00:00

It doesn't trim just symbols that are totally unused in-tree - it trims the symbols unused by any in-tree modules actually built. If you've done a 'make localmodconfig' and only build a hundred or so modules, it's pretty likely that your out-of-tree module will come up lacking something... Hopefully this will save the next guy from a Homer Simpson "D'oh!" moment. Link: http://lkml.kernel.org/r/10177.1469787292@turing-police.cc.vt.edu Signed-off-by: Valdis Kletnieks Cc: Michal Marek Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds