The code, #undef CONFIG_OPTIMIZE_INLINING, is not working as expected
because <linux/compiler_types.h> is parsed before vclock_gettime.c since
28128c61e0 ("kconfig.h: Include compiler types to avoid missed struct
attributes").
Since then, <linux/compiler_types.h> is included really early by using the
'-include' option. So, you cannot negate the decision of
<linux/compiler_types.h> in this way.
You can confirm it by checking the pre-processed code, like this:
$ make arch/x86/entry/vdso/vdso32/vclock_gettime.i
There is no difference with/without CONFIG_CC_OPTIMIZE_FOR_SIZE.
It is about two years since 28128c61e0. Nobody has reported a problem
(or, nobody has even noticed the fact that this code is not working).
It is ugly and unreliable to attempt to undefine a CONFIG option from C
files, and anyway the inlining heuristic is up to the compiler.
Just remove the broken code.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: David Miller <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20200220110807.32534-1-masahiroy@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Here are 3 SPDX patches for 5.7-rc1.
One fixes up the SPDX tag for a single driver, while the other two go
through the tree and add SPDX tags for all of the .gitignore files as
needed.
Nothing too complex, but you will get a merge conflict with your current
tree, that should be trivial to handle (one file modified by two things,
one file deleted.)
All 3 of these have been in linux-next for a while, with no reported
issues other than the merge conflict.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx
Pull SPDX updates from Greg KH:
"Here are three SPDX patches for 5.7-rc1.
One fixes up the SPDX tag for a single driver, while the other two go
through the tree and add SPDX tags for all of the .gitignore files as
needed.
Nothing too complex, but you will get a merge conflict with your
current tree, that should be trivial to handle (one file modified by
two things, one file deleted.)
All three of these have been in linux-next for a while, with no
reported issues other than the merge conflict"
* tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx:
ASoC: MT6660: make spdxcheck.py happy
.gitignore: add SPDX License Identifier
.gitignore: remove too obvious comments
Pull x86 cleanups from Ingo Molnar:
"This topic tree contains more commits than usual:
- most of it are uaccess cleanups/reorganization by Al
- there's a bunch of prototype declaration (--Wmissing-prototypes)
cleanups
- misc other cleanups all around the map"
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
x86/mm/set_memory: Fix -Wmissing-prototypes warnings
x86/efi: Add a prototype for efi_arch_mem_reserve()
x86/mm: Mark setup_emu2phys_nid() static
x86/jump_label: Move 'inline' keyword placement
x86/platform/uv: Add a missing prototype for uv_bau_message_interrupt()
kill uaccess_try()
x86: unsafe_put-style macro for sigmask
x86: x32_setup_rt_frame(): consolidate uaccess areas
x86: __setup_rt_frame(): consolidate uaccess areas
x86: __setup_frame(): consolidate uaccess areas
x86: setup_sigcontext(): list user_access_{begin,end}() into callers
x86: get rid of put_user_try in __setup_rt_frame() (both 32bit and 64bit)
x86: ia32_setup_rt_frame(): consolidate uaccess areas
x86: ia32_setup_frame(): consolidate uaccess areas
x86: ia32_setup_sigcontext(): lift user_access_{begin,end}() into the callers
x86/alternatives: Mark text_poke_loc_init() static
x86/cpu: Fix a -Wmissing-prototypes warning for init_ia32_feat_ctl()
x86/mm: Drop pud_mknotpresent()
x86: Replace setup_irq() by request_irq()
x86/configs: Slightly reduce defconfigs
...
Pull x86 build updates from Ingo Molnar:
"A handful of updates: two linker script cleanups and a stock
defconfig+allmodconfig bootability fix"
* 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/vdso: Discard .note.gnu.property sections in vDSO
x86, vmlinux.lds: Add RUNTIME_DISCARD_EXIT to generic DISCARDS
x86/Kconfig: Make CMDLINE_OVERRIDE depend on non-empty CMDLINE
- Convert the 32bit syscalls to be pt_regs based which removes the
requirement to push all 6 potential arguments onto the stack and
consolidates the interface with the 64bit variant
- The first small portion of the exception and syscall related entry
code consolidation which aims to address the recently discovered
issues vs. RCU, int3, NMI and some other exceptions which can
interrupt any context. The bulk of the changes is still work in
progress and aimed for 5.8.
- A few lockdep namespace cleanups which have been applied into this
branch to keep the prerequisites for the ongoing work confined.
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Merge tag 'x86-entry-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 entry code updates from Thomas Gleixner:
- Convert the 32bit syscalls to be pt_regs based which removes the
requirement to push all 6 potential arguments onto the stack and
consolidates the interface with the 64bit variant
- The first small portion of the exception and syscall related entry
code consolidation which aims to address the recently discovered
issues vs. RCU, int3, NMI and some other exceptions which can
interrupt any context. The bulk of the changes is still work in
progress and aimed for 5.8.
- A few lockdep namespace cleanups which have been applied into this
branch to keep the prerequisites for the ongoing work confined.
* tag 'x86-entry-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (35 commits)
x86/entry: Fix build error x86 with !CONFIG_POSIX_TIMERS
lockdep: Rename trace_{hard,soft}{irq_context,irqs_enabled}()
lockdep: Rename trace_softirqs_{on,off}()
lockdep: Rename trace_hardirq_{enter,exit}()
x86/entry: Rename ___preempt_schedule
x86: Remove unneeded includes
x86/entry: Drop asmlinkage from syscalls
x86/entry/32: Enable pt_regs based syscalls
x86/entry/32: Use IA32-specific wrappers for syscalls taking 64-bit arguments
x86/entry/32: Rename 32-bit specific syscalls
x86/entry/32: Clean up syscall_32.tbl
x86/entry: Remove ABI prefixes from functions in syscall tables
x86/entry/64: Add __SYSCALL_COMMON()
x86/entry: Remove syscall qualifier support
x86/entry/64: Remove ptregs qualifier from syscall table
x86/entry: Move max syscall number calculation to syscallhdr.sh
x86/entry/64: Split X32 syscall table into its own file
x86/entry/64: Move sys_ni_syscall stub to common.c
x86/entry/64: Use syscall wrappers for x32_rt_sigreturn
x86/entry: Refactor SYS_NI macros
...
With the command-line option -mx86-used-note=yes which can also be
enabled at binutils build time with:
--enable-x86-used-note generate GNU x86 used ISA and feature properties
the x86 assembler in binutils 2.32 and above generates a program property
note in a note section, .note.gnu.property, to encode used x86 ISAs and
features. But kernel linker script only contains a single NOTE segment:
PHDRS
{
text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
note PT_NOTE FLAGS(4); /* PF_R */
eh_frame_hdr 0x6474e550;
}
The NOTE segment generated by the vDSO linker script is aligned to 4 bytes.
But the .note.gnu.property section must be aligned to 8 bytes on x86-64:
[hjl@gnu-skx-1 vdso]$ readelf -n vdso64.so
Displaying notes found in: .note
Owner Data size Description
Linux 0x00000004 Unknown note type: (0x00000000)
description data: 06 00 00 00
readelf: Warning: note with invalid namesz and/or descsz found at offset 0x20
readelf: Warning: type: 0x78, namesize: 0x00000100, descsize: 0x756e694c, alignment: 8
Since the note.gnu.property section in the vDSO is not checked by the
dynamic linker, discard the .note.gnu.property sections in the vDSO.
[ bp: Massage. ]
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200326174314.254662-1-hjl.tools@gmail.com
Because moar '_' isn't always moar readable.
git grep -l "___preempt_schedule\(_notrace\)*" | while read file;
do
sed -ie 's/___preempt_schedule\(_notrace\)*/preempt_schedule\1_thunk/g' $file;
done
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/20200320115858.995685950@infradead.org
asmlinkage is no longer required since the syscall ABI is now fully under
x86 architecture control. This makes the 32-bit native syscalls a bit more
effecient by passing in regs via EAX instead of on the stack.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200313195144.164260-18-brgerst@gmail.com
Enable pt_regs based syscalls for 32-bit. This makes the 32-bit native
kernel consistent with the 64-bit kernel, and improves the syscall
interface by not needing to push all 6 potential arguments onto the stack.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-17-brgerst@gmail.com
For the 32-bit syscall interface, 64-bit arguments (loff_t) are passed via
a pair of 32-bit registers. These register pairs end up in consecutive stack
slots, which matches the C ABI for 64-bit arguments. But when accessing the
registers directly from pt_regs, the wrapper needs to manually reassemble the
64-bit value. These wrappers already exist for 32-bit compat, so make them
available to 32-bit native in preparation for enabling pt_regs-based syscalls.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-16-brgerst@gmail.com
Rename the syscalls that only exist for 32-bit from x86_* to ia32_* to make it
clear they are for 32-bit only. Also rename the functions to match the syscall
name.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-15-brgerst@gmail.com
After removal of the __ia32_ prefix, remove compat entries that are now
identical to the native entry.
Converted with this script and fixing up whitespace:
while read nr abi name entry compat; do
if [ "${nr:0:1}" = "#" ]; then
echo $nr $abi $name $entry $compat
continue
fi
if [ "$entry" = "$compat" ]; then
compat=""
fi
echo "$nr $abi $name $entry $compat"
done
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-14-brgerst@gmail.com
Move the ABI prefixes to the __SYSCALL_[abi]() macros. This allows removal
of the need to strip the prefix for UML.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-13-brgerst@gmail.com
Syscall qualifier support is no longer needed.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-11-brgerst@gmail.com
Now that the fast syscall path is removed, the ptregs qualifier is unused.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-10-brgerst@gmail.com
Instead of using an array in asm-offsets to calculate the max syscall
number, calculate it when writing out the syscall headers.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-9-brgerst@gmail.com
Since X32 has its own syscall table now, move it to a separate file.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-8-brgerst@gmail.com
so it can be available to multiple syscall tables. Also directly return
-ENOSYS instead of bouncing to the generic sys_ni_syscall().
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-7-brgerst@gmail.com
User space cannot disable interrupts any longer so trace return to user space
unconditionally as IRQS_ON.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200308222609.314596327@linutronix.de
Nothing cares about the -1 "mark as interrupt" in the errorcode of
exception entries. It's only used to fill the error code when a signal is
delivered, but this is already inconsistent vs. 64 bit as there all
exceptions which do not have an error code set it to 0. So if 32 bit
applications would care about this, then they would have noticed more than
a decade ago.
Just use 0 for all excpetions which do not have an errorcode consistently.
This does neither break /proc/$PID/syscall because this interface examines
the error code / syscall number which is on the stack and that is set to -1
(no syscall) in common_exception unconditionally for all exceptions. The
push in the entry stub is just there to fill the hardware error code slot
on the stack for consistency of the stack layout.
A transient observation of 0 is possible, but that's true for the other
exceptions which use 0 already as well and that interface is an unreliable
snapshot of dubious correctness anyway.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/87mu94m7ky.fsf@nanos.tec.linutronix.de
int3 is not using the common_exception path for purely historical reasons,
but there is no reason to keep it the only exception which is different.
Make it use common_exception so the upcoming changes to autogenerate the
entry stubs do not have to special case int3.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200225220217.042369808@linutronix.de
Remove the pointless difference between 32 and 64 bit to make further
unifications simpler.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200225220216.428188397@linutronix.de
All exception entry points must have ASM_CLAC right at the
beginning. The general_protection entry is missing one.
Fixes: e59d1b0a24 ("x86-32, smap: Add STAC/CLAC instructions to 32-bit kernel entry")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200225220216.219537887@linutronix.de
.. in order to fix a couple of -Wmissing-prototypes warnings.
No functional change.
[ bp: Massage commit message and drop newlines. ]
Signed-off-by: Benjamin Thiel <b.thiel@posteo.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200123152754.20149-1-b.thiel@posteo.de
All architectures which use the generic VDSO code have their own storage
for the VDSO clock mode. That's pointless and just requires duplicate code.
X86 abuses the function which retrieves the architecture specific clock
mode storage to mark the clocksource as used in the VDSO. That's silly
because this is invoked on every tick when the VDSO data is updated.
Move this functionality to the clocksource::enable() callback so it gets
invoked once when the clocksource is installed. This allows to make the
clock mode storage generic.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com> (Hyper-V parts)
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> (VDSO parts)
Acked-by: Juergen Gross <jgross@suse.com> (Xen parts)
Link: https://lkml.kernel.org/r/20200207124402.934519777@linutronix.de
In old days, the "host-progs" syntax was used for specifying host
programs. It was renamed to the current "hostprogs-y" in 2004.
It is typically useful in scripts/Makefile because it allows Kbuild to
selectively compile host programs based on the kernel configuration.
This commit renames like follows:
always -> always-y
hostprogs-y -> hostprogs
So, scripts/Makefile will look like this:
always-$(CONFIG_BUILD_BIN2C) += ...
always-$(CONFIG_KALLSYMS) += ...
...
hostprogs := $(always-y) $(always-m)
I think this makes more sense because a host program is always a host
program, irrespective of the kernel configuration. We want to specify
which ones to compile by CONFIG options, so always-y will be handier.
The "always", "hostprogs-y", "hostprogs-m" will be kept for backward
compatibility for a while.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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Merge tag 'threads-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull thread management updates from Christian Brauner:
"Sargun Dhillon over the last cycle has worked on the pidfd_getfd()
syscall.
This syscall allows for the retrieval of file descriptors of a process
based on its pidfd. A task needs to have ptrace_may_access()
permissions with PTRACE_MODE_ATTACH_REALCREDS (suggested by Oleg and
Andy) on the target.
One of the main use-cases is in combination with seccomp's user
notification feature. As a reminder, seccomp's user notification
feature was made available in v5.0. It allows a task to retrieve a
file descriptor for its seccomp filter. The file descriptor is usually
handed of to a more privileged supervising process. The supervisor can
then listen for syscall events caught by the seccomp filter of the
supervisee and perform actions in lieu of the supervisee, usually
emulating syscalls. pidfd_getfd() is needed to expand its uses.
There are currently two major users that wait on pidfd_getfd() and one
future user:
- Netflix, Sargun said, is working on a service mesh where users
should be able to connect to a dns-based VIP. When a user connects
to e.g. 1.2.3.4:80 that runs e.g. service "foo" they will be
redirected to an envoy process. This service mesh uses seccomp user
notifications and pidfd to intercept all connect calls and instead
of connecting them to 1.2.3.4:80 connects them to e.g.
127.0.0.1:8080.
- LXD uses the seccomp notifier heavily to intercept and emulate
mknod() and mount() syscalls for unprivileged containers/processes.
With pidfd_getfd() more uses-cases e.g. bridging socket connections
will be possible.
- The patchset has also seen some interest from the browser corner.
Right now, Firefox is using a SECCOMP_RET_TRAP sandbox managed by a
broker process. In the future glibc will start blocking all signals
during dlopen() rendering this type of sandbox impossible. Hence,
in the future Firefox will switch to a seccomp-user-nofication
based sandbox which also makes use of file descriptor retrieval.
The thread for this can be found at
https://sourceware.org/ml/libc-alpha/2019-12/msg00079.html
With pidfd_getfd() it is e.g. possible to bridge socket connections
for the supervisee (binding to a privileged port) and taking actions
on file descriptors on behalf of the supervisee in general.
Sargun's first version was using an ioctl on pidfds but various people
pushed for it to be a proper syscall which he duely implemented as
well over various review cycles. Selftests are of course included.
I've also added instructions how to deal with merge conflicts below.
There's also a small fix coming from the kernel mentee project to
correctly annotate struct sighand_struct with __rcu to fix various
sparse warnings. We've received a few more such fixes and even though
they are mostly trivial I've decided to postpone them until after -rc1
since they came in rather late and I don't want to risk introducing
build warnings.
Finally, there's a new prctl() command PR_{G,S}ET_IO_FLUSHER which is
needed to avoid allocation recursions triggerable by storage drivers
that have userspace parts that run in the IO path (e.g. dm-multipath,
iscsi, etc). These allocation recursions deadlock the device.
The new prctl() allows such privileged userspace components to avoid
allocation recursions by setting the PF_MEMALLOC_NOIO and
PF_LESS_THROTTLE flags. The patch carries the necessary acks from the
relevant maintainers and is routed here as part of prctl()
thread-management."
* tag 'threads-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
prctl: PR_{G,S}ET_IO_FLUSHER to support controlling memory reclaim
sched.h: Annotate sighand_struct with __rcu
test: Add test for pidfd getfd
arch: wire up pidfd_getfd syscall
pid: Implement pidfd_getfd syscall
vfs, fdtable: Add fget_task helper
Pull openat2 support from Al Viro:
"This is the openat2() series from Aleksa Sarai.
I'm afraid that the rest of namei stuff will have to wait - it got
zero review the last time I'd posted #work.namei, and there had been a
leak in the posted series I'd caught only last weekend. I was going to
repost it on Monday, but the window opened and the odds of getting any
review during that... Oh, well.
Anyway, openat2 part should be ready; that _did_ get sane amount of
review and public testing, so here it comes"
From Aleksa's description of the series:
"For a very long time, extending openat(2) with new features has been
incredibly frustrating. This stems from the fact that openat(2) is
possibly the most famous counter-example to the mantra "don't silently
accept garbage from userspace" -- it doesn't check whether unknown
flags are present[1].
This means that (generally) the addition of new flags to openat(2) has
been fraught with backwards-compatibility issues (O_TMPFILE has to be
defined as __O_TMPFILE|O_DIRECTORY|[O_RDWR or O_WRONLY] to ensure old
kernels gave errors, since it's insecure to silently ignore the
flag[2]). All new security-related flags therefore have a tough road
to being added to openat(2).
Furthermore, the need for some sort of control over VFS's path
resolution (to avoid malicious paths resulting in inadvertent
breakouts) has been a very long-standing desire of many userspace
applications.
This patchset is a revival of Al Viro's old AT_NO_JUMPS[3] patchset
(which was a variant of David Drysdale's O_BENEATH patchset[4] which
was a spin-off of the Capsicum project[5]) with a few additions and
changes made based on the previous discussion within [6] as well as
others I felt were useful.
In line with the conclusions of the original discussion of
AT_NO_JUMPS, the flag has been split up into separate flags. However,
instead of being an openat(2) flag it is provided through a new
syscall openat2(2) which provides several other improvements to the
openat(2) interface (see the patch description for more details). The
following new LOOKUP_* flags are added:
LOOKUP_NO_XDEV:
Blocks all mountpoint crossings (upwards, downwards, or through
absolute links). Absolute pathnames alone in openat(2) do not
trigger this. Magic-link traversal which implies a vfsmount jump is
also blocked (though magic-link jumps on the same vfsmount are
permitted).
LOOKUP_NO_MAGICLINKS:
Blocks resolution through /proc/$pid/fd-style links. This is done
by blocking the usage of nd_jump_link() during resolution in a
filesystem. The term "magic-links" is used to match with the only
reference to these links in Documentation/, but I'm happy to change
the name.
It should be noted that this is different to the scope of
~LOOKUP_FOLLOW in that it applies to all path components. However,
you can do openat2(NO_FOLLOW|NO_MAGICLINKS) on a magic-link and it
will *not* fail (assuming that no parent component was a
magic-link), and you will have an fd for the magic-link.
In order to correctly detect magic-links, the introduction of a new
LOOKUP_MAGICLINK_JUMPED state flag was required.
LOOKUP_BENEATH:
Disallows escapes to outside the starting dirfd's
tree, using techniques such as ".." or absolute links. Absolute
paths in openat(2) are also disallowed.
Conceptually this flag is to ensure you "stay below" a certain
point in the filesystem tree -- but this requires some additional
to protect against various races that would allow escape using
"..".
Currently LOOKUP_BENEATH implies LOOKUP_NO_MAGICLINKS, because it
can trivially beam you around the filesystem (breaking the
protection). In future, there might be similar safety checks done
as in LOOKUP_IN_ROOT, but that requires more discussion.
In addition, two new flags are added that expand on the above ideas:
LOOKUP_NO_SYMLINKS:
Does what it says on the tin. No symlink resolution is allowed at
all, including magic-links. Just as with LOOKUP_NO_MAGICLINKS this
can still be used with NOFOLLOW to open an fd for the symlink as
long as no parent path had a symlink component.
LOOKUP_IN_ROOT:
This is an extension of LOOKUP_BENEATH that, rather than blocking
attempts to move past the root, forces all such movements to be
scoped to the starting point. This provides chroot(2)-like
protection but without the cost of a chroot(2) for each filesystem
operation, as well as being safe against race attacks that
chroot(2) is not.
If a race is detected (as with LOOKUP_BENEATH) then an error is
generated, and similar to LOOKUP_BENEATH it is not permitted to
cross magic-links with LOOKUP_IN_ROOT.
The primary need for this is from container runtimes, which
currently need to do symlink scoping in userspace[7] when opening
paths in a potentially malicious container.
There is a long list of CVEs that could have bene mitigated by
having RESOLVE_THIS_ROOT (such as CVE-2017-1002101,
CVE-2017-1002102, CVE-2018-15664, and CVE-2019-5736, just to name a
few).
In order to make all of the above more usable, I'm working on
libpathrs[8] which is a C-friendly library for safe path resolution.
It features a userspace-emulated backend if the kernel doesn't support
openat2(2). Hopefully we can get userspace to switch to using it, and
thus get openat2(2) support for free once it's ready.
Future work would include implementing things like
RESOLVE_NO_AUTOMOUNT and possibly a RESOLVE_NO_REMOTE (to allow
programs to be sure they don't hit DoSes though stale NFS handles)"
* 'work.openat2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
Documentation: path-lookup: include new LOOKUP flags
selftests: add openat2(2) selftests
open: introduce openat2(2) syscall
namei: LOOKUP_{IN_ROOT,BENEATH}: permit limited ".." resolution
namei: LOOKUP_IN_ROOT: chroot-like scoped resolution
namei: LOOKUP_BENEATH: O_BENEATH-like scoped resolution
namei: LOOKUP_NO_XDEV: block mountpoint crossing
namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution
namei: LOOKUP_NO_SYMLINKS: block symlink resolution
namei: allow set_root() to produce errors
namei: allow nd_jump_link() to produce errors
nsfs: clean-up ns_get_path() signature to return int
namei: only return -ECHILD from follow_dotdot_rcu()
Pull x86 cleanups from Ingo Molnar:
"Misc cleanups all around the map"
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/CPU/AMD: Remove amd_get_topology_early()
x86/tsc: Remove redundant assignment
x86/crash: Use resource_size()
x86/cpu: Add a missing prototype for arch_smt_update()
x86/nospec: Remove unused RSB_FILL_LOOPS
x86/vdso: Provide missing include file
x86/Kconfig: Correct spelling and punctuation
Documentation/x86/boot: Fix typo
x86/boot: Fix a comment's incorrect file reference
x86/process: Remove set but not used variables prev and next
x86/Kconfig: Fix Kconfig indentation
Pull x86 asm updates from Ingo Molnar:
"Misc updates:
- Remove last remaining calls to exception_enter/exception_exit() and
simplify the entry code some more.
- Remove force_iret()
- Add support for "Fast Short Rep Mov", which is available starting
with Ice Lake Intel CPUs - and make the x86 assembly version of
memmove() use REP MOV for all sizes when FSRM is available.
- Micro-optimize/simplify the 32-bit boot code a bit.
- Use a more future-proof SYSRET instruction mnemonic"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot: Simplify calculation of output address
x86/entry/64: Add instruction suffix to SYSRET
x86: Remove force_iret()
x86/cpufeatures: Add support for fast short REP; MOVSB
x86/context-tracking: Remove exception_enter/exit() from KVM_PV_REASON_PAGE_NOT_PRESENT async page fault
x86/context-tracking: Remove exception_enter/exit() from do_page_fault()
/* Background. */
For a very long time, extending openat(2) with new features has been
incredibly frustrating. This stems from the fact that openat(2) is
possibly the most famous counter-example to the mantra "don't silently
accept garbage from userspace" -- it doesn't check whether unknown flags
are present[1].
This means that (generally) the addition of new flags to openat(2) has
been fraught with backwards-compatibility issues (O_TMPFILE has to be
defined as __O_TMPFILE|O_DIRECTORY|[O_RDWR or O_WRONLY] to ensure old
kernels gave errors, since it's insecure to silently ignore the
flag[2]). All new security-related flags therefore have a tough road to
being added to openat(2).
Userspace also has a hard time figuring out whether a particular flag is
supported on a particular kernel. While it is now possible with
contemporary kernels (thanks to [3]), older kernels will expose unknown
flag bits through fcntl(F_GETFL). Giving a clear -EINVAL during
openat(2) time matches modern syscall designs and is far more
fool-proof.
In addition, the newly-added path resolution restriction LOOKUP flags
(which we would like to expose to user-space) don't feel related to the
pre-existing O_* flag set -- they affect all components of path lookup.
We'd therefore like to add a new flag argument.
Adding a new syscall allows us to finally fix the flag-ignoring problem,
and we can make it extensible enough so that we will hopefully never
need an openat3(2).
/* Syscall Prototype. */
/*
* open_how is an extensible structure (similar in interface to
* clone3(2) or sched_setattr(2)). The size parameter must be set to
* sizeof(struct open_how), to allow for future extensions. All future
* extensions will be appended to open_how, with their zero value
* acting as a no-op default.
*/
struct open_how { /* ... */ };
int openat2(int dfd, const char *pathname,
struct open_how *how, size_t size);
/* Description. */
The initial version of 'struct open_how' contains the following fields:
flags
Used to specify openat(2)-style flags. However, any unknown flag
bits or otherwise incorrect flag combinations (like O_PATH|O_RDWR)
will result in -EINVAL. In addition, this field is 64-bits wide to
allow for more O_ flags than currently permitted with openat(2).
mode
The file mode for O_CREAT or O_TMPFILE.
Must be set to zero if flags does not contain O_CREAT or O_TMPFILE.
resolve
Restrict path resolution (in contrast to O_* flags they affect all
path components). The current set of flags are as follows (at the
moment, all of the RESOLVE_ flags are implemented as just passing
the corresponding LOOKUP_ flag).
RESOLVE_NO_XDEV => LOOKUP_NO_XDEV
RESOLVE_NO_SYMLINKS => LOOKUP_NO_SYMLINKS
RESOLVE_NO_MAGICLINKS => LOOKUP_NO_MAGICLINKS
RESOLVE_BENEATH => LOOKUP_BENEATH
RESOLVE_IN_ROOT => LOOKUP_IN_ROOT
open_how does not contain an embedded size field, because it is of
little benefit (userspace can figure out the kernel open_how size at
runtime fairly easily without it). It also only contains u64s (even
though ->mode arguably should be a u16) to avoid having padding fields
which are never used in the future.
Note that as a result of the new how->flags handling, O_PATH|O_TMPFILE
is no longer permitted for openat(2). As far as I can tell, this has
always been a bug and appears to not be used by userspace (and I've not
seen any problems on my machines by disallowing it). If it turns out
this breaks something, we can special-case it and only permit it for
openat(2) but not openat2(2).
After input from Florian Weimer, the new open_how and flag definitions
are inside a separate header from uapi/linux/fcntl.h, to avoid problems
that glibc has with importing that header.
/* Testing. */
In a follow-up patch there are over 200 selftests which ensure that this
syscall has the correct semantics and will correctly handle several
attack scenarios.
In addition, I've written a userspace library[4] which provides
convenient wrappers around openat2(RESOLVE_IN_ROOT) (this is necessary
because no other syscalls support RESOLVE_IN_ROOT, and thus lots of care
must be taken when using RESOLVE_IN_ROOT'd file descriptors with other
syscalls). During the development of this patch, I've run numerous
verification tests using libpathrs (showing that the API is reasonably
usable by userspace).
/* Future Work. */
Additional RESOLVE_ flags have been suggested during the review period.
These can be easily implemented separately (such as blocking auto-mount
during resolution).
Furthermore, there are some other proposed changes to the openat(2)
interface (the most obvious example is magic-link hardening[5]) which
would be a good opportunity to add a way for userspace to restrict how
O_PATH file descriptors can be re-opened.
Another possible avenue of future work would be some kind of
CHECK_FIELDS[6] flag which causes the kernel to indicate to userspace
which openat2(2) flags and fields are supported by the current kernel
(to avoid userspace having to go through several guesses to figure it
out).
[1]: https://lwn.net/Articles/588444/
[2]: https://lore.kernel.org/lkml/CA+55aFyyxJL1LyXZeBsf2ypriraj5ut1XkNDsunRBqgVjZU_6Q@mail.gmail.com
[3]: commit 629e014bb8 ("fs: completely ignore unknown open flags")
[4]: https://sourceware.org/bugzilla/show_bug.cgi?id=17523
[5]: https://lore.kernel.org/lkml/20190930183316.10190-2-cyphar@cyphar.com/
[6]: https://youtu.be/ggD-eb3yPVs
Suggested-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The VVAR page layout depends on whether a task belongs to the root or
non-root time namespace. Whenever a task changes its namespace, the VVAR
page tables are cleared and then they will be re-faulted with a
corresponding layout.
Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-27-dima@arista.com
As timens page has offsets to data on VVAR page VVAR is going
to be accessed shortly. Set it up with timens in one page fault
as optimization.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-26-dima@arista.com
If a task belongs to a time namespace then the VVAR page which contains
the system wide VDSO data is replaced with a namespace specific page
which has the same layout as the VVAR page.
Co-developed-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-25-dima@arista.com
To support time namespaces in the VDSO with a minimal impact on regular non
time namespace affected tasks, the namespace handling needs to be hidden in
a slow path.
The most obvious place is vdso_seq_begin(). If a task belongs to a time
namespace then the VVAR page which contains the system wide VDSO data is
replaced with a namespace specific page which has the same layout as the
VVAR page. That page has vdso_data->seq set to 1 to enforce the slow path
and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce the time
namespace handling path.
The extra check in the case that vdso_data->seq is odd, e.g. a concurrent
update of the VDSO data is in progress, is not really affecting regular
tasks which are not part of a time namespace as the task is spin waiting
for the update to finish and vdso_data->seq to become even again.
If a time namespace task hits that code path, it invokes the corresponding
time getter function which retrieves the real VVAR page, reads host time
and then adds the offset for the requested clock which is stored in the
special VVAR page.
Allocate the time namespace page among VVAR pages and place vdso_data on
it. Provide __arch_get_timens_vdso_data() helper for VDSO code to get the
code-relative position of VVARs on that special page.
Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-23-dima@arista.com
VDSO support for time namespaces needs to set up a page with the same
layout as VVAR. That timens page will be placed on position of VVAR page
inside namespace. That page has vdso_data->seq set to 1 to enforce
the slow path and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce
the time namespace handling path.
To prepare the time namespace page the kernel needs to know the vdso_data
offset. Provide arch_get_vdso_data() helper for locating vdso_data on VVAR
page.
Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-22-dima@arista.com
Forbid splitting VVAR VMA resulting in a stricter ABI and reducing the
amount of corner-cases to consider while working further on VDSO time
namespace support.
As the offset from timens to VVAR page is computed compile-time, the pages
in VVAR should stay together and not being partically mremap()'ed.
Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-20-dima@arista.com
This wires up the pidfd_getfd syscall for all architectures.
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20200107175927.4558-4-sargun@sargun.me
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
ignore_sysret() contains an unsuffixed SYSRET instruction. gas correctly
interprets this as SYSRETL, but leaving it up to gas to guess when there
is no register operand that implies a size is bad practice, and upstream
gas is likely to warn about this in the future. Use SYSRETL explicitly.
This does not change the assembled output.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/038a7c35-062b-a285-c6d2-653b56585844@suse.com
When building with C=1, sparse issues a warning:
CHECK arch/x86/entry/vdso/vdso32-setup.c
arch/x86/entry/vdso/vdso32-setup.c:28:28: warning: symbol 'vdso32_enabled' was not declared. Should it be static?
Provide the missing header file.
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/36224.1575599767@turing-police
Pull x86 fixes from Ingo Molnar:
"Various fixes:
- Fix the PAT performance regression that downgraded write-combining
device memory regions to uncached.
- There's been a number of bugs in 32-bit double fault handling -
hopefully all fixed now.
- Fix an LDT crash
- Fix an FPU over-optimization that broke with GCC9 code
optimizations.
- Misc cleanups"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mm/pat: Fix off-by-one bugs in interval tree search
x86/ioperm: Save an indentation level in tss_update_io_bitmap()
x86/fpu: Don't cache access to fpu_fpregs_owner_ctx
x86/entry/32: Remove unused 'restore_all_notrace' local label
x86/ptrace: Document FSBASE and GSBASE ABI oddities
x86/ptrace: Remove set_segment_reg() implementations for current
x86/traps: die() instead of panicking on a double fault
x86/doublefault/32: Rewrite the x86_32 #DF handler and unify with 64-bit
x86/doublefault/32: Move #DF stack and TSS to cpu_entry_area
x86/doublefault/32: Rename doublefault.c to doublefault_32.c
x86/traps: Disentangle the 32-bit and 64-bit doublefault code
lkdtm: Add a DOUBLE_FAULT crash type on x86
selftests/x86/single_step_syscall: Check SYSENTER directly
x86/mm/32: Sync only to VMALLOC_END in vmalloc_sync_all()
This is a series of cleanups for the y2038 work, mostly intended
for namespace cleaning: the kernel defines the traditional
time_t, timeval and timespec types that often lead to y2038-unsafe
code. Even though the unsafe usage is mostly gone from the kernel,
having the types and associated functions around means that we
can still grow new users, and that we may be missing conversions
to safe types that actually matter.
There are still a number of driver specific patches needed to
get the last users of these types removed, those have been
submitted to the respective maintainers.
Link: https://lore.kernel.org/lkml/20191108210236.1296047-1-arnd@arndb.de/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Merge tag 'y2038-cleanups-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground
Pull y2038 cleanups from Arnd Bergmann:
"y2038 syscall implementation cleanups
This is a series of cleanups for the y2038 work, mostly intended for
namespace cleaning: the kernel defines the traditional time_t, timeval
and timespec types that often lead to y2038-unsafe code. Even though
the unsafe usage is mostly gone from the kernel, having the types and
associated functions around means that we can still grow new users,
and that we may be missing conversions to safe types that actually
matter.
There are still a number of driver specific patches needed to get the
last users of these types removed, those have been submitted to the
respective maintainers"
Link: https://lore.kernel.org/lkml/20191108210236.1296047-1-arnd@arndb.de/
* tag 'y2038-cleanups-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: (26 commits)
y2038: alarm: fix half-second cut-off
y2038: ipc: fix x32 ABI breakage
y2038: fix typo in powerpc vdso "LOPART"
y2038: allow disabling time32 system calls
y2038: itimer: change implementation to timespec64
y2038: move itimer reset into itimer.c
y2038: use compat_{get,set}_itimer on alpha
y2038: itimer: compat handling to itimer.c
y2038: time: avoid timespec usage in settimeofday()
y2038: timerfd: Use timespec64 internally
y2038: elfcore: Use __kernel_old_timeval for process times
y2038: make ns_to_compat_timeval use __kernel_old_timeval
y2038: socket: use __kernel_old_timespec instead of timespec
y2038: socket: remove timespec reference in timestamping
y2038: syscalls: change remaining timeval to __kernel_old_timeval
y2038: rusage: use __kernel_old_timeval
y2038: uapi: change __kernel_time_t to __kernel_old_time_t
y2038: stat: avoid 'time_t' in 'struct stat'
y2038: ipc: remove __kernel_time_t reference from headers
y2038: vdso: powerpc: avoid timespec references
...
Pull scheduler updates from Ingo Molnar:
"The biggest changes in this cycle were:
- Make kcpustat vtime aware (Frederic Weisbecker)
- Rework the CFS load_balance() logic (Vincent Guittot)
- Misc cleanups, smaller enhancements, fixes.
The load-balancing rework is the most intrusive change: it replaces
the old heuristics that have become less meaningful after the
introduction of the PELT metrics, with a grounds-up load-balancing
algorithm.
As such it's not really an iterative series, but replaces the old
load-balancing logic with the new one. We hope there are no
performance regressions left - but statistically it's highly probable
that there *is* going to be some workload that is hurting from these
chnages. If so then we'd prefer to have a look at that workload and
fix its scheduling, instead of reverting the changes"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits)
rackmeter: Use vtime aware kcpustat accessor
leds: Use all-in-one vtime aware kcpustat accessor
cpufreq: Use vtime aware kcpustat accessors for user time
procfs: Use all-in-one vtime aware kcpustat accessor
sched/vtime: Bring up complete kcpustat accessor
sched/cputime: Support other fields on kcpustat_field()
sched/cpufreq: Move the cfs_rq_util_change() call to cpufreq_update_util()
sched/fair: Add comments for group_type and balancing at SD_NUMA level
sched/fair: Fix rework of find_idlest_group()
sched/uclamp: Fix overzealous type replacement
sched/Kconfig: Fix spelling mistake in user-visible help text
sched/core: Further clarify sched_class::set_next_task()
sched/fair: Use mul_u32_u32()
sched/core: Simplify sched_class::pick_next_task()
sched/core: Optimize pick_next_task()
sched/core: Make pick_next_task_idle() more consistent
sched/fair: Better document newidle_balance()
leds: Use vtime aware kcpustat accessor to fetch CPUTIME_SYSTEM
cpufreq: Use vtime aware kcpustat accessor to fetch CPUTIME_SYSTEM
procfs: Use vtime aware kcpustat accessor to fetch CPUTIME_SYSTEM
...
