Patch series "kexec, panic: Making crash_kexec() NMI safe", v4.
This patch (of 2):
Most acquistions of kexec_mutex are done via mutex_trylock() - those were
a direct "translation" from:
8c5a1cf0ad ("kexec: use a mutex for locking rather than xchg()")
there have however been two additions since then that use mutex_lock():
crash_get_memory_size() and crash_shrink_memory().
A later commit will replace said mutex with an atomic variable, and
locking operations will become atomic_cmpxchg(). Rather than having those
mutex_lock() become while (atomic_cmpxchg(&lock, 0, 1)), turn them into
trylocks that can return -EBUSY on acquisition failure.
This does halve the printable size of the crash kernel, but that's still
neighbouring 2G for 32bit kernels which should be ample enough.
Link: https://lkml.kernel.org/r/20220630223258.4144112-1-vschneid@redhat.com
Link: https://lkml.kernel.org/r/20220630223258.4144112-2-vschneid@redhat.com
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Juri Lelli <jlelli@redhat.com>
Cc: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
commit 278311e417 ("kexec, KEYS: Make use of platform keyring for
signature verify") adds platform keyring support on x86 kexec but not
arm64.
The code in bzImage64_verify_sig uses the keys on the
.builtin_trusted_keys, .machine, if configured and enabled,
.secondary_trusted_keys, also if configured, and .platform keyrings
to verify the signed kernel image as PE file.
Cc: kexec@lists.infradead.org
Cc: keyrings@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Reviewed-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Coiby Xu <coxu@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Before commit 105e10e2cf1c ("kexec_file: drop weak attribute from
functions"), there was already no arch-specific implementation
of arch_kexec_kernel_verify_sig. With weak attribute dropped by that
commit, arch_kexec_kernel_verify_sig is completely useless. So clean it
up.
Note later patches are dependent on this patch so it should be backported
to the stable tree as well.
Cc: stable@vger.kernel.org
Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Reviewed-by: Michal Suchanek <msuchanek@suse.de>
Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
[zohar@linux.ibm.com: reworded patch description "Note"]
Link: https://lore.kernel.org/linux-integrity/20220714134027.394370-1-coxu@redhat.com/
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
As requested
(http://lkml.kernel.org/r/87ee0q7b92.fsf@email.froward.int.ebiederm.org),
this series converts weak functions in kexec to use the #ifdef approach.
Quoting the 3e35142ef9 ("kexec_file: drop weak attribute from
arch_kexec_apply_relocations[_add]") changelog:
: Since commit d1bcae833b32f1 ("ELF: Don't generate unused section symbols")
: [1], binutils (v2.36+) started dropping section symbols that it thought
: were unused. This isn't an issue in general, but with kexec_file.c, gcc
: is placing kexec_arch_apply_relocations[_add] into a separate
: .text.unlikely section and the section symbol ".text.unlikely" is being
: dropped. Due to this, recordmcount is unable to find a non-weak symbol in
: .text.unlikely to generate a relocation record against.
This patch (of 2);
Drop __weak attribute from functions in kexec_file.c:
- arch_kexec_kernel_image_probe()
- arch_kimage_file_post_load_cleanup()
- arch_kexec_kernel_image_load()
- arch_kexec_locate_mem_hole()
- arch_kexec_kernel_verify_sig()
arch_kexec_kernel_image_load() calls into kexec_image_load_default(), so
drop the static attribute for the latter.
arch_kexec_kernel_verify_sig() is not overridden by any architecture, so
drop the __weak attribute.
Link: https://lkml.kernel.org/r/cover.1656659357.git.naveen.n.rao@linux.vnet.ibm.com
Link: https://lkml.kernel.org/r/2cd7ca1fe4d6bb6ca38e3283c717878388ed6788.1656659357.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Suggested-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Currently, an unsigned kernel could be kexec'ed when IMA arch specific
policy is configured unless lockdown is enabled. Enforce kernel
signature verification check in the kexec_file_load syscall when IMA
arch specific policy is configured.
Fixes: 99d5cadfde ("kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE")
Reported-and-suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Pull RISC-V updates from Palmer Dabbelt:
- Support for the Svpbmt extension, which allows memory attributes to
be encoded in pages
- Support for the Allwinner D1's implementation of page-based memory
attributes
- Support for running rv32 binaries on rv64 systems, via the compat
subsystem
- Support for kexec_file()
- Support for the new generic ticket-based spinlocks, which allows us
to also move to qrwlock. These should have already gone in through
the asm-geneic tree as well
- A handful of cleanups and fixes, include some larger ones around
atomics and XIP
* tag 'riscv-for-linus-5.19-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (51 commits)
RISC-V: Prepare dropping week attribute from arch_kexec_apply_relocations[_add]
riscv: compat: Using seperated vdso_maps for compat_vdso_info
RISC-V: Fix the XIP build
RISC-V: Split out the XIP fixups into their own file
RISC-V: ignore xipImage
RISC-V: Avoid empty create_*_mapping definitions
riscv: Don't output a bogus mmu-type on a no MMU kernel
riscv: atomic: Add custom conditional atomic operation implementation
riscv: atomic: Optimize dec_if_positive functions
riscv: atomic: Cleanup unnecessary definition
RISC-V: Load purgatory in kexec_file
RISC-V: Add purgatory
RISC-V: Support for kexec_file on panic
RISC-V: Add kexec_file support
RISC-V: use memcpy for kexec_file mode
kexec_file: Fix kexec_file.c build error for riscv platform
riscv: compat: Add COMPAT Kbuild skeletal support
riscv: compat: ptrace: Add compat_arch_ptrace implement
riscv: compat: signal: Add rt_frame implementation
riscv: add memory-type errata for T-Head
...
Since commit d1bcae833b32f1 ("ELF: Don't generate unused section
symbols") [1], binutils (v2.36+) started dropping section symbols that
it thought were unused. This isn't an issue in general, but with
kexec_file.c, gcc is placing kexec_arch_apply_relocations[_add] into a
separate .text.unlikely section and the section symbol ".text.unlikely"
is being dropped. Due to this, recordmcount is unable to find a non-weak
symbol in .text.unlikely to generate a relocation record against.
Address this by dropping the weak attribute from these functions.
Instead, follow the existing pattern of having architectures #define the
name of the function they want to override in their headers.
[1] https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d1bcae833b32f1
[akpm@linux-foundation.org: arch/s390/include/asm/kexec.h needs linux/module.h]
Link: https://lkml.kernel.org/r/20220519091237.676736-1-naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When CONFIG_KEXEC_FILE is set for riscv platform, the compilation of
kernel/kexec_file.c generate build error:
kernel/kexec_file.c: In function 'crash_prepare_elf64_headers':
./arch/riscv/include/asm/page.h:110:71: error: request for member 'virt_addr' in something not a structure or union
110 | ((x) >= PAGE_OFFSET && (!IS_ENABLED(CONFIG_64BIT) || (x) < kernel_map.virt_addr))
| ^
./arch/riscv/include/asm/page.h:131:2: note: in expansion of macro 'is_linear_mapping'
131 | is_linear_mapping(_x) ? \
| ^~~~~~~~~~~~~~~~~
./arch/riscv/include/asm/page.h:140:31: note: in expansion of macro '__va_to_pa_nodebug'
140 | #define __phys_addr_symbol(x) __va_to_pa_nodebug(x)
| ^~~~~~~~~~~~~~~~~~
./arch/riscv/include/asm/page.h:143:24: note: in expansion of macro '__phys_addr_symbol'
143 | #define __pa_symbol(x) __phys_addr_symbol(RELOC_HIDE((unsigned long)(x), 0))
| ^~~~~~~~~~~~~~~~~~
kernel/kexec_file.c:1327:36: note: in expansion of macro '__pa_symbol'
1327 | phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
This occurs is because the "kernel_map" referenced in macro
is_linear_mapping() is suppose to be the one of struct kernel_mapping
defined in arch/riscv/mm/init.c, but the 2nd argument of
crash_prepare_elf64_header() has same symbol name, in expansion of macro
is_linear_mapping in function crash_prepare_elf64_header(), "kernel_map"
actually is the local variable.
Signed-off-by: Liao Chang <liaochang1@huawei.com>
Link: https://lore.kernel.org/r/20220408100914.150110-2-lizhengyu3@huawei.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The fields ima_buffer_addr and ima_buffer_size in "struct kimage_arch"
for powerpc are used to carry forward the IMA measurement list across
kexec system call. These fields are not architecture specific, but are
currently limited to powerpc.
arch_ima_add_kexec_buffer() defined in "arch/powerpc/kexec/ima.c"
sets ima_buffer_addr and ima_buffer_size for the kexec system call.
This function does not have architecture specific code, but is
currently limited to powerpc.
Move ima_buffer_addr and ima_buffer_size to "struct kimage".
Set ima_buffer_addr and ima_buffer_size in ima_add_kexec_buffer()
in security/integrity/ima/ima_kexec.c.
Co-developed-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
Signed-off-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Suggested-by: Will Deacon <will@kernel.org>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210221174930.27324-9-nramas@linux.microsoft.com
ELF related fields elf_headers, elf_headers_sz, and elf_load_addr are
defined in architecture specific 'struct kimage_arch' for x86, powerpc,
and arm64. The name of these fields are different in these
architectures that makes it hard to have a common code for setting up
the device tree for kexec system call.
Move the ELF fields to 'struct kimage' defined in include/linux/kexec.h
so common code can use it.
Suggested-by: Rob Herring <robh@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210221174930.27324-2-nramas@linux.microsoft.com
Pull arm64 fixes from Will Deacon:
"The big one is a fix for the VHE enabling path during early boot,
where the code enabling the MMU wasn't necessarily in the identity map
of the new page-tables, resulting in a consistent crash with 64k
pages. In fixing that, we noticed some missing barriers too, so we
added those for the sake of architectural compliance.
Other than that, just the usual merge window trickle. There'll be more
to come, too.
Summary:
- Fix lockdep false alarm on resume-from-cpuidle path
- Fix memory leak in kexec_file
- Fix module linker script to work with GDB
- Fix error code when trying to use uprobes with AArch32 instructions
- Fix late VHE enabling with 64k pages
- Add missing ISBs after TLB invalidation
- Fix seccomp when tracing syscall -1
- Fix stacktrace return code at end of stack
- Fix inconsistent whitespace for pointer return values
- Fix compiler warnings when building with W=1"
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: stacktrace: Report when we reach the end of the stack
arm64: ptrace: Fix seccomp of traced syscall -1 (NO_SYSCALL)
arm64: Add missing ISB after invalidating TLB in enter_vhe
arm64: Add missing ISB after invalidating TLB in __primary_switch
arm64: VHE: Enable EL2 MMU from the idmap
KVM: arm64: make the hyp vector table entries local
arm64/mm: Fixed some coding style issues
arm64: uprobe: Return EOPNOTSUPP for AARCH32 instruction probing
kexec: move machine_kexec_post_load() to public interface
arm64 module: set plt* section addresses to 0x0
arm64: kexec_file: fix memory leakage in create_dtb() when fdt_open_into() fails
arm64: spectre: Prevent lockdep splat on v4 mitigation enable path
IMA allocates kernel virtual memory to carry forward the measurement
list, from the current kernel to the next kernel on kexec system call,
in ima_add_kexec_buffer() function. This buffer is not freed before
completing the kexec system call resulting in memory leak.
Add ima_buffer field in "struct kimage" to store the virtual address
of the buffer allocated for the IMA measurement list.
Free the memory allocated for the IMA measurement list in
kimage_file_post_load_cleanup() function.
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Suggested-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Fixes: 7b8589cc29 ("ima: on soft reboot, save the measurement list")
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Some architectures may have special memory regions, within the given
memory range, which can't be used for the buffer in a kexec segment.
Implement weak arch_kexec_locate_mem_hole() definition which arch code
may override, to take care of special regions, while trying to locate
a memory hole.
Also, add the missing declarations for arch overridable functions and
and drop the __weak descriptors in the declarations to avoid non-weak
definitions from becoming weak.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Pingfan Liu <piliu@redhat.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Acked-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/159602273603.575379.17665852963340380839.stgit@hbathini
There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
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 9d1f8be5cf ("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
...
Right now powerpc provides an implementation to read elf files
with the kexec_file_load() syscall. Make that available as a public
kexec interface so it can be re-used on other architectures.
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Helge Deller <deller@gmx.de>
This is a preparatory patch for kexec_file_load() lockdown. A locked down
kernel needs to prevent unsigned kernel images from being loaded with
kexec_file_load(). Currently, the only way to force the signature
verification is compiling with KEXEC_VERIFY_SIG. This prevents loading
usigned images even when the kernel is not locked down at runtime.
This patch splits KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE.
Analogous to the MODULE_SIG and MODULE_SIG_FORCE for modules, KEXEC_SIG
turns on the signature verification but allows unsigned images to be
loaded. KEXEC_SIG_FORCE disallows images without a valid signature.
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
cc: kexec@lists.infradead.org
Signed-off-by: James Morris <jmorris@namei.org>
Memblock list is another source for usable system memory layout.
So move powerpc's arch_kexec_walk_mem() to common code so that other
memblock-based architectures, particularly arm64, can also utilise it.
A moved function is now renamed to kexec_walk_memblock() and integrated
into kexec_locate_mem_hole(), which will now be usable for all
architectures with no need for overriding arch_kexec_walk_mem().
With this change, arch_kexec_walk_mem() need no longer be a weak function,
and was now renamed to kexec_walk_resources().
Since powerpc doesn't support kdump in its kexec_file_load(), the current
kexec_walk_memblock() won't work for kdump either in this form, this will
be fixed in the next patch.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Acked-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Since s390 already knows where to locate buffers, calling
arch_kexec_mem_walk() has no sense. So we can just drop it as kbuf->mem
indicates this while all other architectures sets it to 0 initially.
This change is a preparatory work for the next patch, where all the
variant memory walks, either on system resource or memblock, will be
put in one common place so that it will satisfy all the architectures'
need.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
