(cherry picked from commit caf7501a1b4ec964190f31f9c3f163de252273b8)
There's a risk that a kernel which has full retpoline mitigations becomes
vulnerable when a module gets loaded that hasn't been compiled with the
right compiler or the right option.
To enable detection of that mismatch at module load time, add a module info
string "retpoline" at build time when the module was compiled with
retpoline support. This only covers compiled C source, but assembler source
or prebuilt object files are not checked.
If a retpoline enabled kernel detects a non retpoline protected module at
load time, print a warning and report it in the sysfs vulnerability file.
[ tglx: Massaged changelog ]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: gregkh@linuxfoundation.org
Cc: torvalds@linux-foundation.org
Cc: jeyu@kernel.org
Cc: arjan@linux.intel.com
Link: https://lkml.kernel.org/r/20180125235028.31211-1-andi@firstfloor.org
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
[jwang: port to 4.4]
Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c153693d7eb9eeb28478aa2deaaf0b4e7b5ff5e9 upstream.
PowerPC64 uses the symbol .TOC. much as other targets use
_GLOBAL_OFFSET_TABLE_. It identifies the value of the GOT pointer (or in
powerpc parlance, the TOC pointer). Global offset tables are generally
local to an executable or shared library, or in the kernel, module. Thus
it does not make sense for a module to resolve a relocation against
.TOC. to the kernel's .TOC. value. A module has its own .TOC., and
indeed the powerpc64 module relocation processing ignores the kernel
value of .TOC. and instead calculates a module-local value.
This patch removes code involved in exporting the kernel .TOC., tweaks
modpost to ignore an undefined .TOC., and the module loader to twiddle
the section symbol so that .TOC. isn't seen as undefined.
Note that if the kernel was compiled with -msingle-pic-base then ELFv2
would not have function global entry code setting up r2. In that case
the module call stubs would need to be modified to set up r2 using the
kernel .TOC. value, requiring some of this code to be reinstated.
mpe: Furthermore a change in binutils master (not yet released) causes
the current way we handle the TOC to no longer work when building with
MODVERSIONS=y and RELOCATABLE=n. The symptom is that modules can not be
loaded due to there being no version found for TOC.
Signed-off-by: Alan Modra <amodra@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In our ARC toolchain the default linker script includes special
sections used for code and data located in special fast memory.
To avoid warnings we add these sections i.e. .cmem* and .fmt_slot*
to white list.
Signed-off-by: Noam Camus <noamc@ezchip.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The section mismatch warning can be easy to miss during the kernel build
process. Allow it to be marked as fatal to be easily caught and prevent
bugs from slipping in.
Setting CONFIG_SECTION_MISMATCH_WARN_ONLY=y causes these warnings to be
non-fatal, since there are a number of section mismatches when using
allmodconfig on some architectures, and we do not want to break these
builds by default.
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Change-Id: Ic346706e3297c9f0d790e3552aa94e5cff9897a6
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Module symbols have a limited length, but currently the build system
allows the build finishing even if the driver code contains a too long
symbol name, which eventually overflows the modversion_info[] item.
The compiler may catch at compiling *.mod.c like
CC xxx.mod.o
xxx.mod.c:18:16: warning: initializer-string for array of chars is too long
but it's merely a warning.
This patch adds the check of the symbol length in modpost and stops
the build properly.
Currently MODULE_NAME_LEN is defined in modpost.c instead of referring
to the definition in kernel header because including linux/module.h is
messy and we must cover cross-compilation.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The tilegx and tilepro compilers use .coldtext for their unlikely
executed text section name, so an __attribute__((cold)) function
will (when compiled with higher optimization levels) land in
the .coldtext section.
Modify modpost to add .coldtext to the set of OTHER_TEXT_SECTIONS
so we don't get warnings about referencing such a section in an
__ex_table block, and then also modify arch/tile/lib/memcpy_user_64.c
so that it uses plain ".coldtext" instead of ".coldtext.memcpy".
The latter naming is a relic of an earlier use of -ffunction-sections,
which we no longer use by default.
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Currently an allyesconfig build [gcc-4.9.1] can generate the following:
WARNING: vmlinux.o(.text.unlikely+0x3864): Section mismatch in
reference from the function cpumask_empty.constprop.3() to the
variable .init.data:nmi_ipi_mask
which comes from the cpumask_empty usage in arch/x86/kernel/nmi_selftest.c.
Normally we would not see a symbol entry for cpumask_empty since it is:
static inline bool cpumask_empty(const struct cpumask *srcp)
however in this case, the variant of the symbol gets emitted when GCC does
constant propagation optimization.
Fix things up so that any locally optimized constprop variants don't warn
when accessing variables that live in the __init sections.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Currently the match() function supports a leading * to match any
prefix and a trailing * to match any suffix. However there currently
is not a combination of both that can be used to target matches of
whole families of functions that share a common substring.
Here we expand the *foo and foo* match to also support *foo* with
the goal of targeting compiler generated symbol names that contain
strings like ".constprop." and ".isra."
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Trying to match the SHT_NUL section isn't useful and causes build failures
on parisc and mn10300 since the addition of section strict white-listing
and __ex_table sanitizing.
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: 050e57fd59 ("modpost: add strict white-listing when referencing....")
Fixes: 52dc0595d5 ("modpost: handle relocations mismatch in __ex_table.")
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
As Guenter pointed out, we were never really calculating the extable entry
size because the pointer arithmetic was simply wrong. We want to check
we're handling the second relocation in __ex_table to infer an entry size,
but we were using (void*) pointers instead of Elf_Rel[a]* ones.
This fixes the problem by moving that check in the caller (since we can
deal with different types of relocations) and add is_second_extable_reloc()
to make the whole thing more readable.
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
CC: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
As Guenter pointed out, we want to assert that extable_entry_size has been
discovered and not the other way around. Moreover, this sanity check is
only valid when we're not dealing with the first relocation in __ex_table,
since we have not discovered the extable entry size at that point.
This was leading to a divide-by-zero on some architectures and make the
build fail.
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
CC: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
52dc0595d5 introduced OTHER_TEXT_SECTIONS for identifying what
sections could validly have __ex_table entries. Unfortunately, it
wasn't tested with -ffunction-sections, which some architectures
use.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
32-bit and 64-bit ARM use these sections to store executable code, so
they must be whitelisted in modpost's table of valid text sections.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
struct section_check is used as a generic way of describing what
relocations are authorized/forbidden when running modpost. This commit
tries to describe how each field is used.
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (Fixed "mist"ake)
__ex_table is a simple table section where each entry is a pair of
addresses - the first address is an address which can fault in kernel
space, and the second address points to where the kernel should jump to
when handling that fault. This is how copy_from_user() does not crash the
kernel if userspace gives a borked pointer for example.
If one of these addresses point to a non-executable section, something is
seriously wrong since it either means the kernel will never fault from
there or it will not be able to jump to there. As both cases are serious
enough, we simply error out in these cases so the build fails and the
developper has to fix the issue.
In case the section is executable, but it isn't referenced in our list of
authorized sections to point to from __ex_table, we just dump a warning
giving more information about it. We do this in case the new section is
executable but isn't supposed to be executed by the kernel. This happened
with .altinstr_replacement, which is executable but is only used to copy
instructions from - we should never have our instruction pointer pointing
in .altinstr_replacement. Admitedly, a proper fix in that case would be to
just set .altinstr_replacement NX, but we need to warn about future cases
like this.
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (added long casts)
This will be useful when we want to have special handlers which need to go
through more hops to print useful information to the user.
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
sched.text and .kprobes.text should behave exactly like .text with regards
to how we should warn about referencing sections which might get discarded
at runtime.
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Prints a warning when a section references a section outside a strict
white-list. This will be useful to print a warning if __ex_table
references a non-executable section.
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Pull arm64 updates from Catalin Marinas:
- eBPF JIT compiler for arm64
- CPU suspend backend for PSCI (firmware interface) with standard idle
states defined in DT (generic idle driver to be merged via a
different tree)
- Support for CONFIG_DEBUG_SET_MODULE_RONX
- Support for unmapped cpu-release-addr (outside kernel linear mapping)
- set_arch_dma_coherent_ops() implemented and bus notifiers removed
- EFI_STUB improvements when base of DRAM is occupied
- Typos in KGDB macros
- Clean-up to (partially) allow kernel building with LLVM
- Other clean-ups (extern keyword, phys_addr_t usage)
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (51 commits)
arm64: Remove unneeded extern keyword
ARM64: make of_device_ids const
arm64: Use phys_addr_t type for physical address
aarch64: filter $x from kallsyms
arm64: Use DMA_ERROR_CODE to denote failed allocation
arm64: Fix typos in KGDB macros
arm64: insn: Add return statements after BUG_ON()
arm64: debug: don't re-enable debug exceptions on return from el1_dbg
Revert "arm64: dmi: Add SMBIOS/DMI support"
arm64: Implement set_arch_dma_coherent_ops() to replace bus notifiers
of: amba: use of_dma_configure for AMBA devices
arm64: dmi: Add SMBIOS/DMI support
arm64: Correct ftrace calls to aarch64_insn_gen_branch_imm()
arm64:mm: initialize max_mapnr using function set_max_mapnr
setup: Move unmask of async interrupts after possible earlycon setup
arm64: LLVMLinux: Fix inline arm64 assembly for use with clang
arm64: pageattr: Correctly adjust unaligned start addresses
net: bpf: arm64: fix module memory leak when JIT image build fails
arm64: add PSCI CPU_SUSPEND based cpu_suspend support
arm64: kernel: introduce cpu_init_idle CPU operation
...
Similar to ARM, AArch64 is generating $x and $d syms... which isn't
terribly helpful when looking at %pF output and the like. Filter those
out in kallsyms, modpost and when looking at module symbols.
Seems simplest since none of these check EM_ARM anyway, to just add it
to the strchr used, rather than trying to make things overly
complicated.
initcall_debug improves:
dmesg_before.txt: initcall $x+0x0/0x154 [sg] returned 0 after 26331 usecs
dmesg_after.txt: initcall init_sg+0x0/0x154 [sg] returned 0 after 15461 usecs
Signed-off-by: Kyle McMartin <kyle@redhat.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Avoid the variable length array (vla), just use PATH_MAX instead.
This not only makes this code clang friedly, it also leads to a
code size reduction:
text data bss dec hex filename
51765 2224 12416 66405 10365 scripts/mod/modpost.old
51677 2224 12416 66317 1030d scripts/mod/modpost.new
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Internally used symbols of modpost don't need to be externally visible;
make them static. Also constify the string arrays so they resist in the
r/o section instead of being runtime writable.
Those changes lead to a small size reduction as can be seen below:
text data bss dec hex filename
51381 2640 12416 66437 10385 scripts/mod/modpost.old
51765 2224 12416 66405 10365 scripts/mod/modpost.new
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
For several years, the pattern "foo$" has effectively been treated as
equivalent to "foo" due to a bug in the (misnamed) helper
number_prefix(). This hasn't been observed to cause any problems, so
remove the broken $ functionality and change all foo$ patterns to foo.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
