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The threads allocated inside the kernel have only a single page of
stack. Unfortunately, the vfprintf function in standard glibc may use
too much stack-space, overflowing it.
To make os_info safe to be used by helper threads, use the kernel
vscnprintf function into a smallish buffer and write out the information
to stderr.
Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
For the detection code to check whether SYSEMU_SINGLESTEP works
correctly we needed some error cases while stopping to be non-fatal.
However, at this point stop_ptraced_child must always succeed, and we
can therefore simplify it slightly to exit immediately on error.
Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
start_userspace is only called from exactly one location, and the passed
pointer for the userspace process stack cannot be NULL.
Remove the check, without changing the control flow.
Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
These features have existed since Linux 2.6.14 and can be considered
widely available at this point. Also drop the backward compatibility
code for PTRACE_SETOPTIONS.
Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
----
v2:
* Continue to define PTRACE_SYSEMU_SINGLESTEP as glibc only added it in
version 2.27.
Signed-off-by: Richard Weinberger <richard@nod.at>
__cant_sleep was already used and exported by the scheduler.
The name had to be changed to a UML specific one.
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Reviewed-by: Peter Lafreniere <peter@n8pjl.ca>
Signed-off-by: Richard Weinberger <richard@nod.at>
`strncpy` is deprecated for use on NUL-terminated destination strings [1].
`gate_buf` should always be NUL-terminated and does not require
NUL-padding. It is used as a string arg inside an argv array given to
`run_helper()`. Due to this, let's use `strscpy` as it guarantees
NUL-terminated on the destination buffer preventing potential buffer
overreads [2].
This exact invocation was changed from `strcpy` to `strncpy` in commit
7879b1d94b ("um,ethertap: use strncpy") back in 2015. Let's continue
hardening our `str*cpy` apis and use the newer and safer `strscpy`!
Link: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings[1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230911-strncpy-arch-um-os-linux-drivers-ethertap_user-c-v1-1-d9e53f52ab32@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
- Carve out the new CONFIG_LIST_HARDENED as a more focused subset of
CONFIG_DEBUG_LIST (Marco Elver).
- Fix kallsyms lookup failure under Clang LTO (Yonghong Song).
- Clarify documentation for CONFIG_UBSAN_TRAP (Jann Horn).
- Flexible array member conversion not carried in other tree (Gustavo
A. R. Silva).
- Various strlcpy() and strncpy() removals not carried in other trees
(Azeem Shaikh, Justin Stitt).
- Convert nsproxy.count to refcount_t (Elena Reshetova).
- Add handful of __counted_by annotations not carried in other trees,
as well as an LKDTM test.
- Fix build failure with gcc-plugins on GCC 14+.
- Fix selftests to respect SKIP for signal-delivery tests.
- Fix CFI warning for paravirt callback prototype.
- Clarify documentation for seq_show_option_n() usage.
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Merge tag 'hardening-v6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull hardening updates from Kees Cook:
"As has become normal, changes are scattered around the tree (either
explicitly maintainer Acked or for trivial stuff that went ignored):
- Carve out the new CONFIG_LIST_HARDENED as a more focused subset of
CONFIG_DEBUG_LIST (Marco Elver)
- Fix kallsyms lookup failure under Clang LTO (Yonghong Song)
- Clarify documentation for CONFIG_UBSAN_TRAP (Jann Horn)
- Flexible array member conversion not carried in other tree (Gustavo
A. R. Silva)
- Various strlcpy() and strncpy() removals not carried in other trees
(Azeem Shaikh, Justin Stitt)
- Convert nsproxy.count to refcount_t (Elena Reshetova)
- Add handful of __counted_by annotations not carried in other trees,
as well as an LKDTM test
- Fix build failure with gcc-plugins on GCC 14+
- Fix selftests to respect SKIP for signal-delivery tests
- Fix CFI warning for paravirt callback prototype
- Clarify documentation for seq_show_option_n() usage"
* tag 'hardening-v6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (23 commits)
LoadPin: Annotate struct dm_verity_loadpin_trusted_root_digest with __counted_by
kallsyms: Change func signature for cleanup_symbol_name()
kallsyms: Fix kallsyms_selftest failure
nsproxy: Convert nsproxy.count to refcount_t
integrity: Annotate struct ima_rule_opt_list with __counted_by
lkdtm: Add FAM_BOUNDS test for __counted_by
Compiler Attributes: counted_by: Adjust name and identifier expansion
um: refactor deprecated strncpy to memcpy
um: vector: refactor deprecated strncpy
alpha: Replace one-element array with flexible-array member
hardening: Move BUG_ON_DATA_CORRUPTION to hardening options
list: Introduce CONFIG_LIST_HARDENED
list_debug: Introduce inline wrappers for debug checks
compiler_types: Introduce the Clang __preserve_most function attribute
gcc-plugins: Rename last_stmt() for GCC 14+
selftests/harness: Actually report SKIP for signal tests
x86/paravirt: Fix tlb_remove_table function callback prototype warning
EISA: Replace all non-returning strlcpy with strscpy
perf: Replace strlcpy with strscpy
um: Remove strlcpy declaration
...
This reverts commit 9b0da3f223.
The sigio.c is clearly user space code which is handled by
arch/um/scripts/Makefile.rules (see USER_OBJS rule).
The above mentioned commit simply broke this agreement,
we may not use Linux kernel internal headers in them without
thorough thinking.
Hence, revert the wrong commit.
Link: https://lkml.kernel.org/r/20230724143131.30090-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307212304.cH79zJp1-lkp@intel.com/
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Herve Codina <herve.codina@bootlin.com>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Richard Weinberger <richard@nod.at>
Cc: Yang Guang <yang.guang5@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
- Remove the deprecated rule to build *.dtbo from *.dts
- Refactor section mismatch detection in modpost
- Fix bogus ARM section mismatch detections
- Fix error of 'make gtags' with O= option
- Add Clang's target triple to KBUILD_CPPFLAGS to fix a build error with
the latest LLVM version
- Rebuild the built-in initrd when KBUILD_BUILD_TIMESTAMP is changed
- Ignore more compiler-generated symbols for kallsyms
- Fix 'make local*config' to handle the ${CONFIG_FOO} form in Makefiles
- Enable more kernel-doc warnings with W=2
- Refactor <linux/export.h> by generating KSYMTAB data by modpost
- Deprecate <asm/export.h> and <asm-generic/export.h>
- Remove the EXPORT_DATA_SYMBOL macro
- Move the check for static EXPORT_SYMBOL back to modpost, which makes
the build faster
- Re-implement CONFIG_TRIM_UNUSED_KSYMS with one-pass algorithm
- Warn missing MODULE_DESCRIPTION when building modules with W=1
- Make 'make clean' robust against too long argument error
- Exclude more objects from GCOV to fix CFI failures with GCOV
- Allow 'make modules_install' to install modules.builtin and
modules.builtin.modinfo even when CONFIG_MODULES is disabled
- Include modules.builtin and modules.builtin.modinfo in the linux-image
Debian package even when CONFIG_MODULES is disabled
- Revive "Entering directory" logging for the latest Make version
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Merge tag 'kbuild-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Remove the deprecated rule to build *.dtbo from *.dts
- Refactor section mismatch detection in modpost
- Fix bogus ARM section mismatch detections
- Fix error of 'make gtags' with O= option
- Add Clang's target triple to KBUILD_CPPFLAGS to fix a build error
with the latest LLVM version
- Rebuild the built-in initrd when KBUILD_BUILD_TIMESTAMP is changed
- Ignore more compiler-generated symbols for kallsyms
- Fix 'make local*config' to handle the ${CONFIG_FOO} form in Makefiles
- Enable more kernel-doc warnings with W=2
- Refactor <linux/export.h> by generating KSYMTAB data by modpost
- Deprecate <asm/export.h> and <asm-generic/export.h>
- Remove the EXPORT_DATA_SYMBOL macro
- Move the check for static EXPORT_SYMBOL back to modpost, which makes
the build faster
- Re-implement CONFIG_TRIM_UNUSED_KSYMS with one-pass algorithm
- Warn missing MODULE_DESCRIPTION when building modules with W=1
- Make 'make clean' robust against too long argument error
- Exclude more objects from GCOV to fix CFI failures with GCOV
- Allow 'make modules_install' to install modules.builtin and
modules.builtin.modinfo even when CONFIG_MODULES is disabled
- Include modules.builtin and modules.builtin.modinfo in the
linux-image Debian package even when CONFIG_MODULES is disabled
- Revive "Entering directory" logging for the latest Make version
* tag 'kbuild-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (72 commits)
modpost: define more R_ARM_* for old distributions
kbuild: revive "Entering directory" for Make >= 4.4.1
kbuild: set correct abs_srctree and abs_objtree for package builds
scripts/mksysmap: Ignore prefixed KCFI symbols
kbuild: deb-pkg: remove the CONFIG_MODULES check in buildeb
kbuild: builddeb: always make modules_install, to install modules.builtin*
modpost: continue even with unknown relocation type
modpost: factor out Elf_Sym pointer calculation to section_rel()
modpost: factor out inst location calculation to section_rel()
kbuild: Disable GCOV for *.mod.o
kbuild: Fix CFI failures with GCOV
kbuild: make clean rule robust against too long argument error
script: modpost: emit a warning when the description is missing
kbuild: make modules_install copy modules.builtin(.modinfo)
linux/export.h: rename 'sec' argument to 'license'
modpost: show offset from symbol for section mismatch warnings
modpost: merge two similar section mismatch warnings
kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion
modpost: use null string instead of NULL pointer for default namespace
modpost: squash sym_update_namespace() into sym_add_exported()
...
This reverts commit cead61a671.
It exported __stack_smash_handler and __guard, while they may not be
defined by anyone.
The code *declares* __stack_smash_handler and __guard. It does not
create weak symbols. If no external library is linked, they are left
undefined, but yet exported.
If a loadable module tries to access non-existing symbols, bad things
(a page fault, NULL pointer dereference, etc.) will happen. So, the
current code is wrong and dangerous.
If the code were written as follows, it would *define* them as weak
symbols so modules would be able to get access to them.
void (*__stack_smash_handler)(void *) __attribute__((weak));
EXPORT_SYMBOL(__stack_smash_handler);
long __guard __attribute__((weak));
EXPORT_SYMBOL(__guard);
In fact, modpost forbids exporting undefined symbols. It shows an error
message if it detects such a mistake.
ERROR: modpost: "..." [...] was exported without definition
Unfortunately, it is checked only when the code is built as modular.
The problem described above has been unnoticed for a long time because
arch/um/os-Linux/user_syms.c is always built-in.
With a planned change in Kbuild, exporting undefined symbols will always
result in a build error instead of a run-time error. It is a good thing,
but we need to fix the breakage in advance.
One fix is to define weak symbols as shown above. An alternative is to
export them conditionally as follows:
#ifdef CONFIG_STACKPROTECTOR
extern void __stack_smash_handler(void *);
EXPORT_SYMBOL(__stack_smash_handler);
external long __guard;
EXPORT_SYMBOL(__guard);
#endif
This is what other architectures do; EXPORT_SYMBOL(__stack_chk_guard)
is guarded by #ifdef CONFIG_STACKPROTECTOR.
However, adding the #ifdef guard is not sensible because UML cannot
enable the stack-protector in the first place! (Please note UML does
not select HAVE_STACKPROTECTOR in Kconfig.)
So, the code is already broken (and unused) in multiple ways.
Just remove.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
- Make stub data pages configurable
- Make it harder to mix user and kernel code by accident
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Merge tag 'uml-for-linus-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux
Pull uml updates from Richard Weinberger:
- Make stub data pages configurable
- Make it harder to mix user and kernel code by accident
* tag 'uml-for-linus-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux:
um: make stub data pages size tweakable
um: prevent user code in modules
um: further clean up user_syms
um: don't export printf()
um: hostfs: define our own API boundary
um: add __weak for exported functions
There's a lot of code here that hard-codes that the
data is a single page, and right now that seems to
be sufficient, but to make it easier to change this
in the future, add a new STUB_DATA_PAGES constant
and use it throughout the code.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Make some cleanups, add and fix some comments and document
here that we shouldn't export (libc) symbols for "_user.c"
code, rather such should work like hostfs does now.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Since printf() cannot be used in kernel threads (it
uses too much stack space) don't export it for modules
either.
This should leave us exporting only things that are
absolutely critical (such as memset and friends) and
things that are injected by the compiler (stack guard
and similar.)
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Instead of exporting the set of functions provided by
glibc that are needed for hostfs_user.c, just build that
into the kernel image whenever hostfs is built, and then
export _those_ functions cleanly, to be independent of
the libc implementation.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
If the exported glibc functions don't exist, we get link
failures. Avoid that by adding __weak so they're allowed
to not exist.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
ELF is acronym and therefore should be spelled in all caps.
I left one exception at Documentation/arm/nwfpe/nwfpe.rst which looks like
being written in the first person.
Link: https://lkml.kernel.org/r/Y/3wGWQviIOkyLJW@p183
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
- Add support for rust (yay!)
- Add support for LTO
- Add platform bus support to virtio-pci
- Various virtio fixes
- Coding style, spelling cleanups
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Merge tag 'uml-for-linus-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux
Pull UML updates from Richard Weinberger:
- Add support for rust (yay!)
- Add support for LTO
- Add platform bus support to virtio-pci
- Various virtio fixes
- Coding style, spelling cleanups
* tag 'uml-for-linus-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (27 commits)
Documentation: rust: Fix arch support table
uml: vector: Remove unused definitions VECTOR_{WRITE,HEADERS}
um: virt-pci: properly remove PCI device from bus
um: virtio_uml: move device breaking into workqueue
um: virtio_uml: mark device as unregistered when breaking it
um: virtio_uml: free command if adding to virtqueue failed
UML: define RUNTIME_DISCARD_EXIT
virt-pci: add platform bus support
um-virt-pci: Make max delay configurable
um: virt-pci: implement pcibios_get_phb_of_node()
um: Support LTO
um: put power options in a menu
um: Use CFLAGS_vmlinux
um: Prevent building modules incompatible with MODVERSIONS
um: Avoid pcap multiple definition errors
um: Make the definition of cpu_data more compatible
x86: um: vdso: Add '%rcx' and '%r11' to the syscall clobber list
rust: arch/um: Add support for CONFIG_RUST under x86_64 UML
rust: arch/um: Disable FP/SIMD instruction to match x86
rust: arch/um: Use 'pie' relocation mode under UML
...
I added $(srctree)/ to some included Makefiles in the following commits:
- 3204a7fb98 ("kbuild: prefix $(srctree)/ to some included Makefiles")
- d828563955 ("kbuild: do not require sub-make for separate output tree builds")
They were a preparation for removing --include-dir flag.
I have never thought --include-dir useful. Rather, it _is_ harmful.
For example, run the following commands:
$ make -s ARCH=x86 mrproper defconfig
$ make ARCH=arm O=foo dtbs
make[1]: Entering directory '/tmp/linux/foo'
HOSTCC scripts/basic/fixdep
Error: kernelrelease not valid - run 'make prepare' to update it
UPD include/config/kernel.release
make[1]: Leaving directory '/tmp/linux/foo'
The first command configures the source tree for x86. The next command
tries to build ARM device trees in the separate foo/ directory - this
must stop because the directory foo/ has not been configured yet.
However, due to --include-dir=$(abs_srctree), the top Makefile includes
the wrong include/config/auto.conf from the source tree and continues
building. Kbuild traverses the directory tree, but of course it does
not work correctly. The Error message is also pointless - 'make prepare'
does not help at all for fixing the issue.
This commit fixes more arch Makefile, and finally removes --include-dir
from the top Makefile.
There are more breakages under drivers/, but I do not volunteer to fix
them all. I just moved --include-dir to drivers/Makefile.
With this commit, the second command will stop with a sensible message.
$ make -s ARCH=x86 mrproper defconfig
$ make ARCH=arm O=foo dtbs
make[1]: Entering directory '/tmp/linux/foo'
SYNC include/config/auto.conf.cmd
***
*** The source tree is not clean, please run 'make ARCH=arm mrproper'
*** in /tmp/linux
***
make[2]: *** [../Makefile:646: outputmakefile] Error 1
/tmp/linux/Makefile:770: include/config/auto.conf.cmd: No such file or directory
make[1]: *** [/tmp/linux/Makefile:793: include/config/auto.conf.cmd] Error 2
make[1]: Leaving directory '/tmp/linux/foo'
make: *** [Makefile:226: __sub-make] Error 2
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This means having the string literal in one line and using __func__
where appropriate.
Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
Return the value epoll_ctl() directly instead of storing it in another
redundant variable.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Signed-off-by: Richard Weinberger <richard@nod.at>
- KASAN support for x86_64
- noreboot command line option, just like qemu's -no-reboot
- Various fixes and cleanups
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Merge tag 'for-linus-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml
Pull UML updates from Richard Weinberger:
- KASAN support for x86_64
- noreboot command line option, just like qemu's -no-reboot
- Various fixes and cleanups
* tag 'for-linus-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
um: include sys/types.h for size_t
um: Replace to_phys() and to_virt() with less generic function names
um: Add missing apply_returns()
um: add "noreboot" command line option for PANIC_TIMEOUT=-1 setups
um: include linux/stddef.h for __always_inline
UML: add support for KASAN under x86_64
mm: Add PAGE_ALIGN_DOWN macro
um: random: Don't initialise hwrng struct with zero
um: remove unused mm_copy_segments
um: remove unused variable
um: Remove straying parenthesis
um: x86: print RIP with symbol
arch: um: Fix build for statically linked UML w/ constructors
x86/um: Kconfig: Fix indentation
um/drivers: Kconfig: Fix indentation
um: Kconfig: Fix indentation
UML generally does not provide access to special CPU instructions like
RDRAND, and execution tends to be rather deterministic, with no real
hardware interrupts, making good randomness really very hard, if not
all together impossible. Not only is this a security eyebrow raiser, but
it's also quite annoying when trying to do various pieces of UML-based
automation that takes a long time to boot, if ever.
Fix this by trivially calling getrandom() in the host and using that
seed as "bootloader randomness", which initializes the rng immediately
at UML boot.
The old behavior can be restored the same way as on any other arch, by
way of CONFIG_TRUST_BOOTLOADER_RANDOMNESS=n or
random.trust_bootloader=0. So seen from that perspective, this just
makes UML act like other archs, which is positive in its own right.
Additionally, wire up arch_get_random_{int,long}() in the same way, so
that reseeds can also make use of the host RNG, controllable by
CONFIG_TRUST_CPU_RANDOMNESS and random.trust_cpu, per usual.
Cc: stable@vger.kernel.org
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
to_virt() and to_phys() are very generic and may be defined by drivers.
As it turns out, commit 9409c9b670 ("pmem: refactor pmem_clear_poison()")
did exactly that. This results in build errors such as the following
when trying to build um:allmodconfig.
drivers/nvdimm/pmem.c: In function ‘pmem_dax_zero_page_range’:
./arch/um/include/asm/page.h:105:20: error:
too few arguments to function ‘to_phys’
105 | #define __pa(virt) to_phys((void *) (unsigned long) (virt))
| ^~~~~~~
Use less generic function names for the um specific to_phys() and to_virt()
functions to fix the problem and to avoid similar problems in the future.
Fixes: 9409c9b670 ("pmem: refactor pmem_clear_poison()")
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
QEMU has a -no-reboot option, which halts instead of reboots when the
guest asks to reboot. This is invaluable when used with
CONFIG_PANIC_TIMEOUT=-1 (and panic_on_warn), because it allows panics
and warnings to be caught immediately in CI. Implement this in UML too,
by way of a basic setup param.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Make KASAN run on User Mode Linux on x86_64.
The UML-specific KASAN initializer uses mmap to map the ~16TB of shadow
memory to the location defined by KASAN_SHADOW_OFFSET. kasan_init()
utilizes constructors to initialize KASAN before main().
The location of the KASAN shadow memory, starting at
KASAN_SHADOW_OFFSET, can be configured using the KASAN_SHADOW_OFFSET
option. The default location of this offset is 0x100000000000, which
keeps it out-of-the-way even on UML setups with more "physical" memory.
For low-memory setups, 0x7fff8000 can be used instead, which fits in an
immediate and is therefore faster, as suggested by Dmitry Vyukov. There
is usually enough free space at this location; however, it is a config
option so that it can be easily changed if needed.
Note that, unlike KASAN on other architectures, vmalloc allocations
still use the shadow memory allocated upfront, rather than allocating
and free-ing it per-vmalloc allocation.
If another architecture chooses to go down the same path, we should
replace the checks for CONFIG_UML with something more generic, such
as:
- A CONFIG_KASAN_NO_SHADOW_ALLOC option, which architectures could set
- or, a way of having architecture-specific versions of these vmalloc
and module shadow memory allocation options.
Also note that, while UML supports both KASAN in inline mode
(CONFIG_KASAN_INLINE) and static linking (CONFIG_STATIC_LINK), it does
not support both at the same time.
Signed-off-by: Patricia Alfonso <trishalfonso@google.com>
Co-developed-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
The variable dead is initialized but never used otherwise.
Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
The UML function names to_virt() and to_phys() are exposed by UML
headers, and are very generic and may be defined by drivers. As it
turns out, commit 9409c9b670 ("pmem: refactor pmem_clear_poison()")
did exactly that.
This results in build errors such as the following when trying to build
um:allmodconfig:
drivers/nvdimm/pmem.c: In function ‘pmem_dax_zero_page_range’:
./arch/um/include/asm/page.h:105:20: error: too few arguments to function ‘to_phys’
105 | #define __pa(virt) to_phys((void *) (unsigned long) (virt))
| ^~~~~~~
Use less generic function names for the um specific to_phys() and
to_virt() functions to fix the problem and to avoid similar problems in
the future.
Fixes: 9409c9b670 ("pmem: refactor pmem_clear_poison()")
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Devicetree support (for testing)
- Various cleanups and fixes: UBD, port_user, uml_mconsole
- Maintainer update
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Merge tag 'for-linus-5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml
Pull UML updates from Richard Weinberger:
- Devicetree support (for testing)
- Various cleanups and fixes: UBD, port_user, uml_mconsole
- Maintainer update
* tag 'for-linus-5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
um: run_helper: Write error message to kernel log on exec failure on host
um: port_user: Improve error handling when port-helper is not found
um: port_user: Allow setting path to port-helper using UML_PORT_HELPER envvar
um: port_user: Search for in.telnetd in PATH
um: clang: Strip out -mno-global-merge from USER_CFLAGS
docs: UML: Mention telnetd for port channel
um: Remove unused timeval_to_ns() function
um: Fix uml_mconsole stop/go
um: Cleanup syscall_handler_t definition/cast, fix warning
uml: net: vector: fix const issue
um: Fix WRITE_ZEROES in the UBD Driver
um: Migrate vector drivers to NAPI
um: Fix order of dtb unflatten/early init
um: fix and optimize xor select template for CONFIG64 and timetravel mode
um: Document dtb command line option
lib/logic_iomem: correct fallback config references
um: Remove duplicated include in syscalls_64.c
MAINTAINERS: Update UserModeLinux entry
The best place to log errors from the host side is in the kernel log within
the UML guest. Letting the user now that exec() failed and why is very
helpful when the user is trying to determine why some aspect of UML is not
working. For instance, when telneting into the UML instance, if the
connection is established and then immediately dropped, this may be due to
exec() failing because in.telnetd is not found.
Signed-off-by: Glenn Washburn <development@efficientek.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
The timeval_to_ns() function doesn't appear to be used anywhere, as far
as I (or git grep) can tell, and clang throws up a warning about it:
../arch/um/os-Linux/time.c:21:25: warning: unused function 'timeval_to_ns' [-Wunused-function]
static inline long long timeval_to_ns(const struct timeval *tv)
^
1 warning generated.
Signed-off-by: David Gow <davidgow@google.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Call to fallocate with FALLOC_FL_PUNCH_HOLE on a device backed by a sparse
file can end up by missing data, zeroes data range, if the underlying file
is used with a tool like bmaptool which will referenced only used spaces.
Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Use the macro 'swap()' defined in 'include/linux/minmax.h' to avoid
opencoding it.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Yang Guang <yang.guang5@zte.com.cn>
Signed-off-by: Richard Weinberger <richard@nod.at>
The function names init_registers() and restore_registers() are used
in several net/ethernet/ and gpu/drm/ drivers for other purposes (not
calls to UML functions), so rename them.
This fixes multiple build errors.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: linux-um@lists.infradead.org
Signed-off-by: Richard Weinberger <richard@nod.at>
Rename set_signals() as there's at least one driver that
uses the same name and can now be built on UM due to PCI
support, and thus we can get symbol conflicts.
Also rename set_signals_trace() to be consistent.
Reported-by: kernel test robot <lkp@intel.com>
Fixes: 68f5d3f3b6 ("um: add PCI over virtio emulation driver")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Delete/fixup few includes in anticipation of global -isystem compile
option removal.
Note: crypto/aegis128-neon-inner.c keeps <stddef.h> due to redefinition
of uintptr_t error (one definition comes from <stddef.h>, another from
<linux/types.h>).
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
GCC assumes that stack is aligned to 16-byte on call sites [1].
Since GCC 8, GCC began using 16-byte aligned SSE instructions to
implement assignments to structs on stack. When
CC_OPTIMIZE_FOR_PERFORMANCE is enabled, this affects
os-Linux/sigio.c, write_sigio_thread:
struct pollfds *fds, tmp;
tmp = current_poll;
Note that struct pollfds is exactly 16 bytes in size.
GCC 8+ generates assembly similar to:
movdqa (%rdi),%xmm0
movaps %xmm0,-0x50(%rbp)
This is an issue, because movaps will #GP if -0x50(%rbp) is not
aligned to 16 bytes [2], and how rbp gets assigned to is via glibc
clone thread_start, then function prologue, going though execution
trace similar to (showing only relevant instructions):
sub $0x10,%rsi
mov %rcx,0x8(%rsi)
mov %rdi,(%rsi)
syscall
pop %rax
pop %rdi
callq *%rax
push %rbp
mov %rsp,%rbp
The stack pointer always points to the topmost element on stack,
rather then the space right above the topmost. On push, the
pointer decrements first before writing to the memory pointed to
by it. Therefore, there is no need to have the stack pointer
pointer always point to valid memory unless the stack is poped;
so the `- sizeof(void *)` in the code is unnecessary.
On the other hand, glibc reserves the 16 bytes it needs on stack
and pops itself, so by the call instruction the stack pointer
is exactly the caller-supplied sp. It then push the 16 bytes of
the return address and the saved stack pointer, so the base
pointer will be 16-byte aligned if and only if the caller
supplied sp is 16-byte aligned. Therefore, the caller must supply
a 16-byte aligned pointer, which `stack + UM_KERN_PAGE_SIZE`
already satisfies.
On a side note, musl is unaffected by this issue because it forces
16 byte alignment via `and $-16,%rsi` in its clone wrapper.
Similarly, glibc i386 is also unaffected because it has
`andl $0xfffffff0, %ecx`.
To reproduce this bug, enable CONFIG_UML_RTC and
CC_OPTIMIZE_FOR_PERFORMANCE. uml_rtc will call
add_sigio_fd which will then cause write_sigio_thread to either go
into segfault loop or panic with "Segfault with no mm".
Similarly, signal stacks will be aligned by the host kernel upon
signal delivery. `- sizeof(void *)` to sigaltstack is
unconventional and extraneous.
On a related note, initialization of longjmp buffers do require
`- sizeof(void *)`. This is to account for the return address
that would have been pushed to the stack at the call site.
The reason for uml to respect 16-byte alignment, rather than
telling GCC to assume 8-byte alignment like the host kernel since
commit d9b0cde91c ("x86-64, gcc: Use
-mpreferred-stack-boundary=3 if supported"), is because uml links
against libc. There is no reason to assume libc is also compiled
with that flag and assumes 8-byte alignment rather than 16-byte.
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838
[2] https://c9x.me/x86/html/file_module_x86_id_180.html
Signed-off-by: YiFei Zhu <zhuyifei1999@gmail.com>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
1. Reflect host cpu flags into the UML instance so they can
be used to select the correct implementations for xor, crypto, etc.
2. Reflect host cache alignment into UML instance. This is
important when running 32 bit on a 64 bit host as 32 bit by
default aligns to 32 while the actual alignment should be 64.
Ditto for some Xeons which align at 128.
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
We should be able to ndelay() from any context, even from an
interrupt context! However, this is broken (not functionally,
but locking-wise) in time-travel because we'll get into the
time-travel code and enable interrupts to handle messages on
other time-travel aware subsystems (only virtio for now).
Luckily, I've already reworked the time-travel aware signal
(interrupt) delivery for suspend/resume to have a time travel
handler, which runs directly in the context of the signal and
not from the Linux interrupt.
In order to fix this time-travel issue then, we need to do a
few things:
1) rework the signal handling code to call time-travel handlers
(only) if interrupts are disabled but signals aren't blocked,
instead of marking it only pending there. This is needed to
not deadlock other communication.
2) rework time-travel to not enable interrupts while it's
waiting for a message;
3) rework time-travel to not (just) disable interrupts but
rather block signals at a lower level while it needs them
disabled for communicating with the controller.
Finally, since now we can actually spend even virtual time
in interrupts-disabled sections, the delay warning when we
deliver a time-travel delayed interrupt is no longer valid,
things can (and should) now get delayed.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Use signals_enabled instead of always jumping through
a function call to read it, there's not much point in
that.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This mostly reverts the old commit 3963333fe6 ("uml: cover stubs
with a VMA") which had added a VMA to the existing PTEs. However,
there's no real reason to have the PTEs in the first place and the
VMA cannot be 'fixed' in place, which leads to bugs that userspace
could try to unmap them and be forcefully killed, or such. Also,
there's a bit of an ugly hole in userspace's address space.
Simplify all this: just install the stub code/page at the top of
the (inner) address space, i.e. put it just above TASK_SIZE. The
pages are simply hard-coded to be mapped in the userspace process
we use to implement an mm context, and they're out of reach of the
inner mmap/munmap/mprotect etc. since they're above TASK_SIZE.
Getting rid of the VMA also makes vma_merge() no longer hit one of
the VM_WARN_ON()s there because we installed a VMA while the code
assumes the stack VMA is the first one.
It also removes a lockdep warning about mmap_sem usage since we no
longer have uml_setup_stubs() and thus no longer need to do any
manipulation that would require mmap_sem in activate_mm().
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
The userspace stacks mostly have a stack (and in the case of the
syscall stub we can just set their stack pointer) that points to
the location of the stub data page already.
Rework the stubs to use the stack pointer to derive the start of
the data page, rather than requiring it to be hard-coded.
In the clone stub, also integrate the int3 into the stack remap,
since we really must not use the stack while we remap it.
This prepares for putting the stub at a variable location that's
not part of the normal address space of the userspace processes
running inside the UML machine.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
If the two are mixed up, then it looks as though the parent
returned an error if the child failed (before) the mmap(),
and then the resulting process never gets killed. Fix this
by splitting the child and parent errors, reporting and
using them appropriately.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
In some cases we can get to fix_range_common() with mmap_sem held,
and in others we get there without it being held. For example, we
get there with it held from sys_mprotect(), and without it held
from fork_handler().
Avoid any issues in this and simply defer killing the task until
it runs the next time. Do it on the mm so that another task that
shares the same mm can't continue running afterwards.
Cc: stable@vger.kernel.org
Fixes: 468f65976a ("um: Fix hung task in fix_range_common()")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Since we're basically debugging the userspace (it runs in ptrace)
it's useful to dump out the registers - but they're not readable,
so if something goes wrong it's hard to say what. Print the names
of registers in the register dump so it's easier to look at.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Changing os_idle_sleep() to use pause() (I accidentally described
it as an empty select() in the commit log because I had changed it
from that to pause() in a later revision) exposed a race condition
in the idle code. The following can happen:
timer_settime(0, 0, {it_interval={tv_sec=0, tv_nsec=0}, it_value={tv_sec=0, tv_nsec=624017}}, NULL) = 0
...
<SIGALRM is delivered but we're already on the way to idle>
pause()
and we now hang forever. This was previously possible as well, but
it could never cause UML to hang for more than a second since we
could only sleep for that much, so at most you'd notice a "hiccup"
in the UML. Obviously, any sort of external interrupt also "saves"
it and interrupts pause().
Fix this by properly handling the race, rather than papering over
it again:
- first, block SIGALRM, and obtain the old signal set
- check the timer
- suspend, waiting for any signal out of the old set, if, and only
if, the timer will fire in the future
- restore the old signal mask
This ensures race-free operation: as it's blocked, the signal won't
be delivered while we're looking at the timer even if it were to be
triggered right _after_ we've returned from timer_gettime() with a
non-zero value (telling us the timer will trigger). Thus, despite
getting to sigsuspend() because timer_gettime() told us we're still
waiting, we'll not hang because sigsuspend() will return immediately
due to the pending signal.
Fixes: 49da38a3ef ("um: Simplify os_idle_sleep() and sleep longer")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
