linux/fs/debugfs/file.c, branch v5.4

Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

2019-09-28T15:14:15Z

Pull kernel lockdown mode from James Morris: "This is the latest iteration of the kernel lockdown patchset, from Matthew Garrett, David Howells and others. From the original description: This patchset introduces an optional kernel lockdown feature, intended to strengthen the boundary between UID 0 and the kernel. When enabled, various pieces of kernel functionality are restricted. Applications that rely on low-level access to either hardware or the kernel may cease working as a result - therefore this should not be enabled without appropriate evaluation beforehand. The majority of mainstream distributions have been carrying variants of this patchset for many years now, so there's value in providing a doesn't meet every distribution requirement, but gets us much closer to not requiring external patches. There are two major changes since this was last proposed for mainline: - Separating lockdown from EFI secure boot. Background discussion is covered here: https://lwn.net/Articles/751061/ - Implementation as an LSM, with a default stackable lockdown LSM module. This allows the lockdown feature to be policy-driven, rather than encoding an implicit policy within the mechanism. The new locked_down LSM hook is provided to allow LSMs to make a policy decision around whether kernel functionality that would allow tampering with or examining the runtime state of the kernel should be permitted. The included lockdown LSM provides an implementation with a simple policy intended for general purpose use. This policy provides a coarse level of granularity, controllable via the kernel command line: lockdown={integrity|confidentiality} Enable the kernel lockdown feature. If set to integrity, kernel features that allow userland to modify the running kernel are disabled. If set to confidentiality, kernel features that allow userland to extract confidential information from the kernel are also disabled. This may also be controlled via /sys/kernel/security/lockdown and overriden by kernel configuration. New or existing LSMs may implement finer-grained controls of the lockdown features. Refer to the lockdown_reason documentation in include/linux/security.h for details. The lockdown feature has had signficant design feedback and review across many subsystems. This code has been in linux-next for some weeks, with a few fixes applied along the way. Stephen Rothwell noted that commit 9d1f8be5cf42 ("bpf: Restrict bpf when kernel lockdown is in confidentiality mode") is missing a Signed-off-by from its author. Matthew responded that he is providing this under category (c) of the DCO" * 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (31 commits) kexec: Fix file verification on S390 security: constify some arrays in lockdown LSM lockdown: Print current->comm in restriction messages efi: Restrict efivar_ssdt_load when the kernel is locked down tracefs: Restrict tracefs when the kernel is locked down debugfs: Restrict debugfs when the kernel is locked down kexec: Allow kexec_file() with appropriate IMA policy when locked down lockdown: Lock down perf when in confidentiality mode bpf: Restrict bpf when kernel lockdown is in confidentiality mode lockdown: Lock down tracing and perf kprobes when in confidentiality mode lockdown: Lock down /proc/kcore x86/mmiotrace: Lock down the testmmiotrace module lockdown: Lock down module params that specify hardware parameters (eg. ioport) lockdown: Lock down TIOCSSERIAL lockdown: Prohibit PCMCIA CIS storage when the kernel is locked down acpi: Disable ACPI table override if the kernel is locked down acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down ACPI: Limit access to custom_method when the kernel is locked down x86/msr: Restrict MSR access when the kernel is locked down x86: Lock down IO port access when the kernel is locked down ...

debugfs: Restrict debugfs when the kernel is locked down

2019-08-20T04:54:17Z

Disallow opening of debugfs files that might be used to muck around when the kernel is locked down as various drivers give raw access to hardware through debugfs. Given the effort of auditing all 2000 or so files and manually fixing each one as necessary, I've chosen to apply a heuristic instead. The following changes are made: (1) chmod and chown are disallowed on debugfs objects (though the root dir can be modified by mount and remount, but I'm not worried about that). (2) When the kernel is locked down, only files with the following criteria are permitted to be opened: - The file must have mode 00444 - The file must not have ioctl methods - The file must not have mmap (3) When the kernel is locked down, files may only be opened for reading. Normal device interaction should be done through configfs, sysfs or a miscdev, not debugfs. Note that this makes it unnecessary to specifically lock down show_dsts(), show_devs() and show_call() in the asus-wmi driver. I would actually prefer to lock down all files by default and have the the files unlocked by the creator. This is tricky to manage correctly, though, as there are 19 creation functions and ~1600 call sites (some of them in loops scanning tables). Signed-off-by: David Howells cc: Andy Shevchenko cc: acpi4asus-user@lists.sourceforge.net cc: platform-driver-x86@vger.kernel.org cc: Matthew Garrett cc: Thomas Gleixner Cc: Greg KH Cc: Rafael J. Wysocki Signed-off-by: Matthew Garrett Signed-off-by: James Morris

debugfs: make debugfs_create_u32_array() return void

2019-06-03T14:34:27Z

The single user of debugfs_create_u32_array() does not care about the return value of it, so make it return void as there is no need to do anything with the return value. Signed-off-by: Greg Kroah-Hartman

debugfs: update documented return values of debugfs helpers

2019-04-25T09:56:50Z

Since commit ff9fb72bc077 ("debugfs: return error values, not NULL") these helper functions do not return NULL anymore (with the exception of debugfs_create_u32_array()). Fixes: ff9fb72bc077 ("debugfs: return error values, not NULL") Signed-off-by: Ronald Tschalär Signed-off-by: Greg Kroah-Hartman

debugfs: Re-use kstrtobool_from_user()

2018-05-14T14:48:18Z

Re-use kstrtobool_from_user() instead of open coded variant. Signed-off-by: Andy Shevchenko Signed-off-by: Greg Kroah-Hartman

vfs: do bulk POLL* -> EPOLL* replacement

2018-02-11T22:34:03Z

This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script: for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^$[^\"]*$$\$/\\1E\\2/" $f; done done with de-mangling cleanups yet to come. NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al. The next patch from Al will sort out the final differences, and we should be all done. Scripted-by: Al Viro Signed-off-by: Linus Torvalds

use linux/poll.h instead of asm/poll.h

2018-02-01T21:23:11Z

The only place that has any business including asm/poll.h is linux/poll.h. Fortunately, asm/poll.h had only been included in 3 places beyond that one, and all of them are trivial to switch to using linux/poll.h. Signed-off-by: Al Viro

fs: annotate ->poll() instances

2017-11-27T21:20:05Z

Signed-off-by: Al Viro

anntotate the places where ->poll() return values go

2017-11-27T21:19:53Z

Signed-off-by: Al Viro

debugfs: Remove redundant license text

2017-11-07T19:25:03Z

Now that the SPDX tag is in all debugfs files, that identifies the license in a specific and legally-defined manner. So the extra GPL text wording can be removed as it is no longer needed at all. This is done on a quest to remove the 700+ different ways that files in the kernel describe the GPL license text. And there's unneeded stuff like the address (sometimes incorrect) for the FSF which is never needed. No copyright headers or other non-license-description text was removed. Cc: Nicolai Stange Signed-off-by: Greg Kroah-Hartman