user/sven/linux.git/kernel/sysctl.c, branch v4.14.231

kernel: sysctl: make drop_caches write-only

2020-01-04T12:59:57Z

[ Upstream commit 204cb79ad42f015312a5bbd7012d09c93d9b46fb ] Currently, the drop_caches proc file and sysctl read back the last value written, suggesting this is somehow a stateful setting instead of a one-time command. Make it write-only, like e.g. compact_memory. While mitigating a VM problem at scale in our fleet, there was confusion about whether writing to this file will permanently switch the kernel into a non-caching mode. This influences the decision making in a tense situation, where tens of people are trying to fix tens of thousands of affected machines: Do we need a rollback strategy? What are the performance implications of operating in a non-caching state for several days? It also caused confusion when the kernel team said we may need to write the file several times to make sure it's effective ("But it already reads back 3?"). Link: http://lkml.kernel.org/r/20191031221602.9375-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Acked-by: Chris Down Acked-by: Vlastimil Babka Acked-by: David Hildenbrand Acked-by: Michal Hocko Acked-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

sysctl: return -EINVAL if val violates minmax

2019-06-15T09:54:51Z

[ Upstream commit e260ad01f0aa9e96b5386d5cd7184afd949dc457 ] Currently when userspace gives us a values that overflow e.g. file-max and other callers of __do_proc_doulongvec_minmax() we simply ignore the new value and leave the current value untouched. This can be problematic as it gives the illusion that the limit has indeed be bumped when in fact it failed. This commit makes sure to return EINVAL when an overflow is detected. Please note that this is a userspace facing change. Link: http://lkml.kernel.org/r/20190210203943.8227-4-christian@brauner.io Signed-off-by: Christian Brauner Acked-by: Luis Chamberlain Cc: Kees Cook Cc: Alexey Dobriyan Cc: Al Viro Cc: Dominik Brodowski Cc: "Eric W. Biederman" Cc: Joe Lawrence Cc: Waiman Long Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

kernel/sysctl.c: fix out-of-bounds access when setting file-max

2019-04-27T07:35:42Z

commit 9002b21465fa4d829edfc94a5a441005cffaa972 upstream. Commit 32a5ad9c2285 ("sysctl: handle overflow for file-max") hooked up min/max values for the file-max sysctl parameter via the .extra1 and .extra2 fields in the corresponding struct ctl_table entry. Unfortunately, the minimum value points at the global 'zero' variable, which is an int. This results in a KASAN splat when accessed as a long by proc_doulongvec_minmax on 64-bit architectures: | BUG: KASAN: global-out-of-bounds in __do_proc_doulongvec_minmax+0x5d8/0x6a0 | Read of size 8 at addr ffff2000133d1c20 by task systemd/1 | | CPU: 0 PID: 1 Comm: systemd Not tainted 5.1.0-rc3-00012-g40b114779944 #2 | Hardware name: linux,dummy-virt (DT) | Call trace: | dump_backtrace+0x0/0x228 | show_stack+0x14/0x20 | dump_stack+0xe8/0x124 | print_address_description+0x60/0x258 | kasan_report+0x140/0x1a0 | __asan_report_load8_noabort+0x18/0x20 | __do_proc_doulongvec_minmax+0x5d8/0x6a0 | proc_doulongvec_minmax+0x4c/0x78 | proc_sys_call_handler.isra.19+0x144/0x1d8 | proc_sys_write+0x34/0x58 | __vfs_write+0x54/0xe8 | vfs_write+0x124/0x3c0 | ksys_write+0xbc/0x168 | __arm64_sys_write+0x68/0x98 | el0_svc_common+0x100/0x258 | el0_svc_handler+0x48/0xc0 | el0_svc+0x8/0xc | | The buggy address belongs to the variable: | zero+0x0/0x40 | | Memory state around the buggy address: | ffff2000133d1b00: 00 00 00 00 00 00 00 00 fa fa fa fa 04 fa fa fa | ffff2000133d1b80: fa fa fa fa 04 fa fa fa fa fa fa fa 04 fa fa fa | >ffff2000133d1c00: fa fa fa fa 04 fa fa fa fa fa fa fa 00 00 00 00 | ^ | ffff2000133d1c80: fa fa fa fa 00 fa fa fa fa fa fa fa 00 00 00 00 | ffff2000133d1d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Fix the splat by introducing a unsigned long 'zero_ul' and using that instead. Link: http://lkml.kernel.org/r/20190403153409.17307-1-will.deacon@arm.com Fixes: 32a5ad9c2285 ("sysctl: handle overflow for file-max") Signed-off-by: Will Deacon Acked-by: Christian Brauner Cc: Kees Cook Cc: Alexey Dobriyan Cc: Matteo Croce Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

sysctl: handle overflow for file-max

2019-04-05T20:31:26Z

[ Upstream commit 32a5ad9c22852e6bd9e74bdec5934ef9d1480bc5 ] Currently, when writing echo 18446744073709551616 > /proc/sys/fs/file-max /proc/sys/fs/file-max will overflow and be set to 0. That quickly crashes the system. This commit sets the max and min value for file-max. The max value is set to long int. Any higher value cannot currently be used as the percpu counters are long ints and not unsigned integers. Note that the file-max value is ultimately parsed via __do_proc_doulongvec_minmax(). This function does not report error when min or max are exceeded. Which means if a value largen that long int is written userspace will not receive an error instead the old value will be kept. There is an argument to be made that this should be changed and __do_proc_doulongvec_minmax() should return an error when a dedicated min or max value are exceeded. However this has the potential to break userspace so let's defer this to an RFC patch. Link: http://lkml.kernel.org/r/20190107222700.15954-3-christian@brauner.io Signed-off-by: Christian Brauner Acked-by: Kees Cook Cc: Alexey Dobriyan Cc: Al Viro Cc: Dominik Brodowski Cc: "Eric W. Biederman" Cc: Joe Lawrence Cc: Luis Chamberlain Cc: Waiman Long [christian@brauner.io: v4] Link: http://lkml.kernel.org/r/20190210203943.8227-3-christian@brauner.io Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

kernel/sysctl.c: add missing range check in do_proc_dointvec_minmax_conv

2019-03-23T13:35:24Z

commit 8cf7630b29701d364f8df4a50e4f1f5e752b2778 upstream. This bug has apparently existed since the introduction of this function in the pre-git era (4500e91754d3 in Thomas Gleixner's history.git, "[NET]: Add proc_dointvec_userhz_jiffies, use it for proper handling of neighbour sysctls."). As a minimal fix we can simply duplicate the corresponding check in do_proc_dointvec_conv(). Link: http://lkml.kernel.org/r/20190207123426.9202-3-zev@bewilderbeest.net Signed-off-by: Zev Weiss Cc: Brendan Higgins Cc: Iurii Zaikin Cc: Kees Cook Cc: Luis Chamberlain Cc: [2.6.2+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

proc/sysctl: fix return error for proc_doulongvec_minmax()

2019-02-12T18:46:09Z

[ Upstream commit 09be178400829dddc1189b50a7888495dd26aa84 ] If the number of input parameters is less than the total parameters, an EINVAL error will be returned. For example, we use proc_doulongvec_minmax to pass up to two parameters with kern_table: { .procname = "monitor_signals", .data = &monitor_sigs, .maxlen = 2*sizeof(unsigned long), .mode = 0644, .proc_handler = proc_doulongvec_minmax, }, Reproduce: When passing two parameters, it's work normal. But passing only one parameter, an error "Invalid argument"(EINVAL) is returned. [root@cl150 ~]# echo 1 2 > /proc/sys/kernel/monitor_signals [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals 1 2 [root@cl150 ~]# echo 3 > /proc/sys/kernel/monitor_signals -bash: echo: write error: Invalid argument [root@cl150 ~]# echo $? 1 [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals 3 2 [root@cl150 ~]# The following is the result after apply this patch. No error is returned when the number of input parameters is less than the total parameters. [root@cl150 ~]# echo 1 2 > /proc/sys/kernel/monitor_signals [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals 1 2 [root@cl150 ~]# echo 3 > /proc/sys/kernel/monitor_signals [root@cl150 ~]# echo $? 0 [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals 3 2 [root@cl150 ~]# There are three processing functions dealing with digital parameters, __do_proc_dointvec/__do_proc_douintvec/__do_proc_doulongvec_minmax. This patch deals with __do_proc_doulongvec_minmax, just as __do_proc_dointvec does, adding a check for parameters 'left'. In __do_proc_douintvec, its code implementation explicitly does not support multiple inputs. static int __do_proc_douintvec(...){ ... /* * Arrays are not supported, keep this simple. *Do not* add * support for them. */ if (vleft != 1) { *lenp = 0; return -EINVAL; } ... } So, just __do_proc_doulongvec_minmax has the problem. And most use of proc_doulongvec_minmax/proc_doulongvec_ms_jiffies_minmax just have one parameter. Link: http://lkml.kernel.org/r/1544081775-15720-1-git-send-email-cheng.lin130@zte.com.cn Signed-off-by: Cheng Lin Acked-by: Luis Chamberlain Reviewed-by: Kees Cook Cc: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

namei: allow restricted O_CREAT of FIFOs and regular files

2018-12-01T08:42:59Z

commit 30aba6656f61ed44cba445a3c0d38b296fa9e8f5 upstream. Disallows open of FIFOs or regular files not owned by the user in world writable sticky directories, unless the owner is the same as that of the directory or the file is opened without the O_CREAT flag. The purpose is to make data spoofing attacks harder. This protection can be turned on and off separately for FIFOs and regular files via sysctl, just like the symlinks/hardlinks protection. This patch is based on Openwall's "HARDEN_FIFO" feature by Solar Designer. This is a brief list of old vulnerabilities that could have been prevented by this feature, some of them even allow for privilege escalation: CVE-2000-1134 CVE-2007-3852 CVE-2008-0525 CVE-2009-0416 CVE-2011-4834 CVE-2015-1838 CVE-2015-7442 CVE-2016-7489 This list is not meant to be complete. It's difficult to track down all vulnerabilities of this kind because they were often reported without any mention of this particular attack vector. In fact, before hardlinks/symlinks restrictions, fifos/regular files weren't the favorite vehicle to exploit them. [s.mesoraca16@gmail.com: fix bug reported by Dan Carpenter] Link: https://lkml.kernel.org/r/20180426081456.GA7060@mwanda Link: http://lkml.kernel.org/r/1524829819-11275-1-git-send-email-s.mesoraca16@gmail.com [keescook@chromium.org: drop pr_warn_ratelimited() in favor of audit changes in the future] [keescook@chromium.org: adjust commit subjet] Link: http://lkml.kernel.org/r/20180416175918.GA13494@beast Signed-off-by: Salvatore Mesoraca Signed-off-by: Kees Cook Suggested-by: Solar Designer Suggested-by: Kees Cook Cc: Al Viro Cc: Dan Carpenter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Loic Signed-off-by: Greg Kroah-Hartman

kmemcheck: rip it out

2018-02-22T14:42:24Z

commit 4675ff05de2d76d167336b368bd07f3fef6ed5a6 upstream. Fix up makefiles, remove references, and git rm kmemcheck. Link: http://lkml.kernel.org/r/20171007030159.22241-4-alexander.levin@verizon.com Signed-off-by: Sasha Levin Cc: Steven Rostedt Cc: Vegard Nossum Cc: Pekka Enberg Cc: Michal Hocko Cc: Eric W. Biederman Cc: Alexander Potapenko Cc: Tim Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

pipe: match pipe_max_size data type with procfs

2017-12-14T08:53:08Z

[ Upstream commit 98159d977f71c3b3dee898d1c34e56f520b094e7 ] Patch series "A few round_pipe_size() and pipe-max-size fixups", v3. While backporting Michael's "pipe: fix limit handling" patchset to a distro-kernel, Mikulas noticed that current upstream pipe limit handling contains a few problems: 1 - procfs signed wrap: echo'ing a large number into /proc/sys/fs/pipe-max-size and then cat'ing it back out shows a negative value. 2 - round_pipe_size() nr_pages overflow on 32bit: this would subsequently try roundup_pow_of_two(0), which is undefined. 3 - visible non-rounded pipe-max-size value: there is no mutual exclusion or protection between the time pipe_max_size is assigned a raw value from proc_dointvec_minmax() and when it is rounded. 4 - unsigned long -> unsigned int conversion makes for potential odd return errors from do_proc_douintvec_minmax_conv() and do_proc_dopipe_max_size_conv(). This version underwent the same testing as v1: https://marc.info/?l=linux-kernel&m=150643571406022&w=2 This patch (of 4): pipe_max_size is defined as an unsigned int: unsigned int pipe_max_size = 1048576; but its procfs/sysctl representation is an integer: static struct ctl_table fs_table[] = { ... { .procname = "pipe-max-size", .data = &pipe_max_size, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &pipe_proc_fn, .extra1 = &pipe_min_size, }, ... that is signed: int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf, size_t *lenp, loff_t *ppos) { ... ret = proc_dointvec_minmax(table, write, buf, lenp, ppos) This leads to signed results via procfs for large values of pipe_max_size: % echo 2147483647 >/proc/sys/fs/pipe-max-size % cat /proc/sys/fs/pipe-max-size -2147483648 Use unsigned operations on this variable to avoid such negative values. Link: http://lkml.kernel.org/r/1507658689-11669-2-git-send-email-joe.lawrence@redhat.com Signed-off-by: Joe Lawrence Reported-by: Mikulas Patocka Reviewed-by: Mikulas Patocka Cc: Michael Kerrisk Cc: Randy Dunlap Cc: Al Viro Cc: Jens Axboe Cc: Josh Poimboeuf Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

Merge branch 'core-watchdog-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2017-10-06T15:36:41Z

Pull watchddog clean-up and fixes from Thomas Gleixner: "The watchdog (hard/softlockup detector) code is pretty much broken in its current state. The patch series addresses this by removing all duct tape and refactoring it into a workable state. The reasons why I ask for inclusion that late in the cycle are: 1) The code causes lockdep splats vs. hotplug locking which get reported over and over. Unfortunately there is no easy fix. 2) The risk of breakage is minimal because it's already broken 3) As 4.14 is a long term stable kernel, I prefer to have working watchdog code in that and the lockdep issues resolved. I wouldn't ask you to pull if 4.14 wouldn't be a LTS kernel or if the solution would be easy to backport. 4) The series was around before the merge window opened, but then got delayed due to the UP failure caused by the for_each_cpu() surprise which we discussed recently. Changes vs. V1: - Addressed your review points - Addressed the warning in the powerpc code which was discovered late - Changed two function names which made sense up to a certain point in the series. Now they match what they do in the end. - Fixed a 'unused variable' warning, which got not detected by the intel robot. I triggered it when trying all possible related config combinations manually. Randconfig testing seems not random enough. The changes have been tested by and reviewed by Don Zickus and tested and acked by Micheal Ellerman for powerpc" * 'core-watchdog-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits) watchdog/core: Put softlockup_threads_initialized under ifdef guard watchdog/core: Rename some softlockup_* functions powerpc/watchdog: Make use of watchdog_nmi_probe() watchdog/core, powerpc: Lock cpus across reconfiguration watchdog/core, powerpc: Replace watchdog_nmi_reconfigure() watchdog/hardlockup/perf: Fix spelling mistake: "permanetely" -> "permanently" watchdog/hardlockup/perf: Cure UP damage watchdog/hardlockup: Clean up hotplug locking mess watchdog/hardlockup/perf: Simplify deferred event destroy watchdog/hardlockup/perf: Use new perf CPU enable mechanism watchdog/hardlockup/perf: Implement CPU enable replacement watchdog/hardlockup/perf: Implement init time detection of perf watchdog/hardlockup/perf: Implement init time perf validation watchdog/core: Get rid of the racy update loop watchdog/core, powerpc: Make watchdog_nmi_reconfigure() two stage watchdog/sysctl: Clean up sysctl variable name space watchdog/sysctl: Get rid of the #ifdeffery watchdog/core: Clean up header mess watchdog/core: Further simplify sysctl handling watchdog/core: Get rid of the thread teardown/setup dance ...