This change adds support for Clang’s forward-edge Control Flow
Integrity (CFI) checking. With CONFIG_CFI_CLANG, the compiler
injects a runtime check before each indirect function call to ensure
the target is a valid function with the correct static type. This
restricts possible call targets and makes it more difficult for
an attacker to exploit bugs that allow the modification of stored
function pointers. For more details, see:
https://clang.llvm.org/docs/ControlFlowIntegrity.html
Clang requires CONFIG_LTO_CLANG to be enabled with CFI to gain
visibility to possible call targets. Kernel modules are supported
with Clang’s cross-DSO CFI mode, which allows checking between
independently compiled components.
With CFI enabled, the compiler injects a __cfi_check() function into
the kernel and each module for validating local call targets. For
cross-module calls that cannot be validated locally, the compiler
calls the global __cfi_slowpath_diag() function, which determines
the target module and calls the correct __cfi_check() function. This
patch includes a slowpath implementation that uses __module_address()
to resolve call targets, and with CONFIG_CFI_CLANG_SHADOW enabled, a
shadow map that speeds up module look-ups by ~3x.
Clang implements indirect call checking using jump tables and
offers two methods of generating them. With canonical jump tables,
the compiler renames each address-taken function to <function>.cfi
and points the original symbol to a jump table entry, which passes
__cfi_check() validation. This isn’t compatible with stand-alone
assembly code, which the compiler doesn’t instrument, and would
result in indirect calls to assembly code to fail. Therefore, we
default to using non-canonical jump tables instead, where the compiler
generates a local jump table entry <function>.cfi_jt for each
address-taken function, and replaces all references to the function
with the address of the jump table entry.
Note that because non-canonical jump table addresses are local
to each component, they break cross-module function address
equality. Specifically, the address of a global function will be
different in each module, as it's replaced with the address of a local
jump table entry. If this address is passed to a different module,
it won’t match the address of the same function taken there. This
may break code that relies on comparing addresses passed from other
components.
CFI checking can be disabled in a function with the __nocfi attribute.
Additionally, CFI can be disabled for an entire compilation unit by
filtering out CC_FLAGS_CFI.
By default, CFI failures result in a kernel panic to stop a potential
exploit. CONFIG_CFI_PERMISSIVE enables a permissive mode, where the
kernel prints out a rate-limited warning instead, and allows execution
to continue. This option is helpful for locating type mismatches, but
should only be enabled during development.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210408182843.1754385-2-samitolvanen@google.com
Smatch complains that:
kernel/module.c:4472 module_kallsyms_on_each_symbol()
error: uninitialized symbol 'ret'.
This warning looks like it could be correct if the &modules list is
empty.
Fixes: 013c1667cf ("kallsyms: refactor {,module_}kallsyms_on_each_symbol")
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
EXPORT_UNUSED_SYMBOL* is not actually used anywhere. Remove the
unused functionality as we generally just remove unused code anyway.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
As far as I can tell this has never been used at all, and certainly
not any time recently.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
struct symsearch is only used inside of module.h, so move the definition
out of module.h.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Simplify the calling convention by passing the find_symbol_args structure
to find_symbol instead of initializing it inside the function.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
each_symbol_section is only called by find_symbol, so merge the two
functions.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
each_symbol_in_section just contains a trivial loop over its arguments.
Just open code the loop in the two callers.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Except for two lockdep asserts module_mutex is only used in module.c.
Remove the two asserts given that the functions they are in are not
exported and just called from the module code, and mark module_mutex
static.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
kallsyms_on_each_symbol and module_kallsyms_on_each_symbol are only used
by the livepatching code, so don't build them if livepatching is not
enabled.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Require an explicit call to module_kallsyms_on_each_symbol to look
for symbols in modules instead of the call from kallsyms_on_each_symbol,
and acquire module_mutex inside of module_kallsyms_on_each_symbol instead
of leaving that up to the caller. Note that this slightly changes the
behavior for the livepatch code in that the symbols from vmlinux are not
iterated anymore if objname is set, but that actually is the desired
behavior in this case.
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Allow for a RCU-sched critical section around find_module, following
the lower level find_module_all helper, and switch the two callers
outside of module.c to use such a RCU-sched critical section instead
of module_mutex.
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
find_module is not used by modular code any more, and random driver code
has no business calling it to start with.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
5fdc7db644 ("module: setup load info before module_sig_check()")
moved the ELF setup, so that it was done before the signature
check. This made the module name available to signature error
messages.
However, the checks for ELF correctness in setup_load_info
are not sufficient to prevent bad memory references due to
corrupted offset fields, indices, etc.
So, there's a regression in behavior here: a corrupt and unsigned
(or badly signed) module, which might previously have been rejected
immediately, can now cause an oops/crash.
Harden ELF handling for module loading by doing the following:
- Move the signature check back up so that it comes before ELF
initialization. It's best to do the signature check to see
if we can trust the module, before using the ELF structures
inside it. This also makes checks against info->len
more accurate again, as this field will be reduced by the
length of the signature in mod_check_sig().
The module name is now once again not available for error
messages during the signature check, but that seems like
a fair tradeoff.
- Check if sections have offset / size fields that at least don't
exceed the length of the module.
- Check if sections have section name offsets that don't fall
outside the section name table.
- Add a few other sanity checks against invalid section indices,
etc.
This is not an exhaustive consistency check, but the idea is to
at least get through the signature and blacklist checks without
crashing because of corrupted ELF info, and to error out gracefully
for most issues that would have caused problems later on.
Fixes: 5fdc7db644 ("module: setup load info before module_sig_check()")
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
clang-12 -fno-pic (since
a084c0388e)
can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail`
on x86. The two forms should have identical behaviors on x86-64 but the
former causes GNU as<2.37 to produce an unreferenced undefined symbol
_GLOBAL_OFFSET_TABLE_.
(On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the
linker behavior is identical as far as Linux kernel is concerned.)
Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what
scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the
problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for
external function calls on x86.
Note: ld -z defs and dynamic loaders do not error for unreferenced
undefined symbols so the module loader is reading too much. If we ever
need to ignore more symbols, the code should be refactored to ignore
unreferenced symbols.
Cc: <stable@vger.kernel.org>
Link: https://github.com/ClangBuiltLinux/linux/issues/1250
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=27178
Reported-by: Marco Elver <elver@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Marco Elver <elver@google.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Summary of modules changes for the 5.11 merge window:
- Fix a race condition between systemd/udev and the module loader.
The module loader was sending a uevent before the module was fully
initialized (i.e., before its init function has been called). This means
udev can start processing the module uevent before the module has
finished initializing, and some udev rules expect that the module has
initialized already upon receiving the uevent. This resulted in some
systemd mount units failing if udev processes the event faster than the
module can finish init. This is fixed by delaying the uevent until after
the module has called its init routine.
- Make the linker array sections for kernel params and module version
attributes more robust by switching to use the alignment of the type in
question. Namely, linker section arrays will be constructed using the
alignment required by the struct (using __alignof__()) as opposed to a
specific value such as sizeof(void *) or sizeof(long). This is less
likely to cause breakages should the size of the type ever change (from
Johan Hovold)
- Fix module state inconsistency by setting it back to GOING when a module
fails to load and is on its way out (from Miroslav Benes)
- Some comment and code cleanups (from Sergey Shtylyov)
Signed-off-by: Jessica Yu <jeyu@kernel.org>
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Merge tag 'modules-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux
Pull modules updates from Jessica Yu:
"Summary of modules changes for the 5.11 merge window:
- Fix a race condition between systemd/udev and the module loader.
The module loader was sending a uevent before the module was fully
initialized (i.e., before its init function has been called). This
means udev can start processing the module uevent before the module
has finished initializing, and some udev rules expect that the
module has initialized already upon receiving the uevent.
This resulted in some systemd mount units failing if udev processes
the event faster than the module can finish init. This is fixed by
delaying the uevent until after the module has called its init
routine.
- Make the linker array sections for kernel params and module version
attributes more robust by switching to use the alignment of the
type in question.
Namely, linker section arrays will be constructed using the
alignment required by the struct (using __alignof__()) as opposed
to a specific value such as sizeof(void *) or sizeof(long). This is
less likely to cause breakages should the size of the type ever
change (Johan Hovold)
- Fix module state inconsistency by setting it back to GOING when a
module fails to load and is on its way out (Miroslav Benes)
- Some comment and code cleanups (Sergey Shtylyov)"
* tag 'modules-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
module: delay kobject uevent until after module init call
module: drop semicolon from version macro
init: use type alignment for kernel parameters
params: clean up module-param macros
params: use type alignment for kernel parameters
params: drop redundant "unused" attributes
module: simplify version-attribute handling
module: drop version-attribute alignment
module: fix comment style
module: add more 'kernel-doc' comments
module: fix up 'kernel-doc' comments
module: only handle errors with the *switch* statement in module_sig_check()
module: avoid *goto*s in module_sig_check()
module: merge repetitive strings in module_sig_check()
module: set MODULE_STATE_GOING state when a module fails to load
Apparently there has been a longstanding race between udev/systemd and
the module loader. Currently, the module loader sends a uevent right
after sysfs initialization, but before the module calls its init
function. However, some udev rules expect that the module has
initialized already upon receiving the uevent.
This race has been triggered recently (see link in references) in some
systemd mount unit files. For instance, the configfs module creates the
/sys/kernel/config mount point in its init function, however the module
loader issues the uevent before this happens. sys-kernel-config.mount
expects to be able to mount /sys/kernel/config upon receipt of the
module loading uevent, but if the configfs module has not called its
init function yet, then this directory will not exist and the mount unit
fails. A similar situation exists for sys-fs-fuse-connections.mount, as
the fuse sysfs mount point is created during the fuse module's init
function. If udev is faster than module initialization then the mount
unit would fail in a similar fashion.
To fix this race, delay the module KOBJ_ADD uevent until after the
module has finished calling its init routine.
References: https://github.com/systemd/systemd/issues/17586
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-By: Nicolas Morey-Chaisemartin <nmoreychaisemartin@suse.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Having real btf_data_size stored in struct module is benefitial to quickly
determine which kernel modules have associated BTF object and which don't.
There is no harm in keeping this info, as opposed to keeping invalid pointer.
Fixes: 607c543f93 ("bpf: Sanitize BTF data pointer after module is loaded")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201203204634.1325171-3-andrii@kernel.org
Given .BTF section is not allocatable, it will get trimmed after module is
loaded. BPF system handles that properly by creating an independent copy of
data. But prevent any accidental misused by resetting the pointer to BTF data.
Fixes: 36e68442d1 ("bpf: Load and verify kernel module BTFs")
Suggested-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jessica Yu <jeyu@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/bpf/20201121070829.2612884-2-andrii@kernel.org
Add kernel module listener that will load/validate and unload module BTF.
Module BTFs gets ID generated for them, which makes it possible to iterate
them with existing BTF iteration API. They are given their respective module's
names, which will get reported through GET_OBJ_INFO API. They are also marked
as in-kernel BTFs for tooling to distinguish them from user-provided BTFs.
Also, similarly to vmlinux BTF, kernel module BTFs are exposed through
sysfs as /sys/kernel/btf/<module-name>. This is convenient for user-space
tools to inspect module BTF contents and dump their types with existing tools:
[vmuser@archvm bpf]$ ls -la /sys/kernel/btf
total 0
drwxr-xr-x 2 root root 0 Nov 4 19:46 .
drwxr-xr-x 13 root root 0 Nov 4 19:46 ..
...
-r--r--r-- 1 root root 888 Nov 4 19:46 irqbypass
-r--r--r-- 1 root root 100225 Nov 4 19:46 kvm
-r--r--r-- 1 root root 35401 Nov 4 19:46 kvm_intel
-r--r--r-- 1 root root 120 Nov 4 19:46 pcspkr
-r--r--r-- 1 root root 399 Nov 4 19:46 serio_raw
-r--r--r-- 1 root root 4094095 Nov 4 19:46 vmlinux
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/bpf/20201110011932.3201430-5-andrii@kernel.org
Many comments in this module do not comply with the preferred multi-line
comment style as reported by 'scripts/checkpatch.pl':
WARNING: Block comments use * on subsequent lines
WARNING: Block comments use a trailing */ on a separate line
Fix those comments, along with (unreported for some reason?) the starts
of the multi-line comments not being /* on their own line...
Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Some functions have the proper 'kernel-doc' comments but these don't start
with proper /** -- fix that, along with adding () to the function name on
the following lines to fully comply with the 'kernel-doc' format.
Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Some 'kernel-doc' function comments do not fully comply with the specified
format due to:
- missing () after the function name;
- "RETURNS:"/"Returns:" instead of "Return:" when documenting the function's
result.
- empty line before describing the function's arguments.
Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Let's handle the successful call of mod_verify_sig() right after that call,
making the *switch* statement only handle the real errors, and then move
the comment from the first *case* before *switch* itself and the comment
before *default* after it. Fix the comment style, add article/comma/dash,
spell out "nomem" as "lack of memory" in these comments, while at it...
Suggested-by: Joe Perches <joe@perches.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Let's move the common handling of the non-fatal errors after the *switch*
statement -- this avoids *goto*s inside that *switch*...
Suggested-by: Joe Perches <joe@perches.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
The 'reason' variable in module_sig_check() points to 3 strings across
the *switch* statement, all needlessly starting with the same text.
Let's put the starting text into the pr_notice() call -- it saves 21
bytes of the object code (x86 gcc 10.2.1).
Suggested-by: Joe Perches <joe@perches.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
If a module fails to load due to an error in prepare_coming_module(),
the following error handling in load_module() runs with
MODULE_STATE_COMING in module's state. Fix it by correctly setting
MODULE_STATE_GOING under "bug_cleanup" label.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Here is the big set of char, misc, and other assorted driver subsystem
patches for 5.10-rc1.
There's a lot of different things in here, all over the drivers/
directory. Some summaries:
- soundwire driver updates
- habanalabs driver updates
- extcon driver updates
- nitro_enclaves new driver
- fsl-mc driver and core updates
- mhi core and bus updates
- nvmem driver updates
- eeprom driver updates
- binder driver updates and fixes
- vbox minor bugfixes
- fsi driver updates
- w1 driver updates
- coresight driver updates
- interconnect driver updates
- misc driver updates
- other minor driver updates
All of these have been in linux-next for a while with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH:
"Here is the big set of char, misc, and other assorted driver subsystem
patches for 5.10-rc1.
There's a lot of different things in here, all over the drivers/
directory. Some summaries:
- soundwire driver updates
- habanalabs driver updates
- extcon driver updates
- nitro_enclaves new driver
- fsl-mc driver and core updates
- mhi core and bus updates
- nvmem driver updates
- eeprom driver updates
- binder driver updates and fixes
- vbox minor bugfixes
- fsi driver updates
- w1 driver updates
- coresight driver updates
- interconnect driver updates
- misc driver updates
- other minor driver updates
All of these have been in linux-next for a while with no reported
issues"
* tag 'char-misc-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (396 commits)
binder: fix UAF when releasing todo list
docs: w1: w1_therm: Fix broken xref, mistakes, clarify text
misc: Kconfig: fix a HISI_HIKEY_USB dependency
LSM: Fix type of id parameter in kernel_post_load_data prototype
misc: Kconfig: add a new dependency for HISI_HIKEY_USB
firmware_loader: fix a kernel-doc markup
w1: w1_therm: make w1_poll_completion static
binder: simplify the return expression of binder_mmap
test_firmware: Test partial read support
firmware: Add request_partial_firmware_into_buf()
firmware: Store opt_flags in fw_priv
fs/kernel_file_read: Add "offset" arg for partial reads
IMA: Add support for file reads without contents
LSM: Add "contents" flag to kernel_read_file hook
module: Call security_kernel_post_load_data()
firmware_loader: Use security_post_load_data()
LSM: Introduce kernel_post_load_data() hook
fs/kernel_read_file: Add file_size output argument
fs/kernel_read_file: Switch buffer size arg to size_t
fs/kernel_read_file: Remove redundant size argument
...
Corentin hit the following workqueue warning when running with
CRYPTO_MANAGER_EXTRA_TESTS:
WARNING: CPU: 2 PID: 147 at kernel/workqueue.c:1473 __queue_work+0x3b8/0x3d0
Modules linked in: ghash_generic
CPU: 2 PID: 147 Comm: modprobe Not tainted
5.6.0-rc1-next-20200214-00068-g166c9264f0b1-dirty #545
Hardware name: Pine H64 model A (DT)
pc : __queue_work+0x3b8/0x3d0
Call trace:
__queue_work+0x3b8/0x3d0
queue_work_on+0x6c/0x90
do_init_module+0x188/0x1f0
load_module+0x1d00/0x22b0
I wasn't able to reproduce on x86 or rpi 3b+.
This is
WARN_ON(!list_empty(&work->entry))
from __queue_work(), and it happens because the init_free_wq work item
isn't initialized in time for a crypto test that requests the gcm
module. Some crypto tests were recently moved earlier in boot as
explained in commit c4741b2305 ("crypto: run initcalls for generic
implementations earlier"), which went into mainline less than two weeks
before the Fixes commit.
Avoid the warning by statically initializing init_free_wq and the
corresponding llist.
Link: https://lore.kernel.org/lkml/20200217204803.GA13479@Red/
Fixes: 1a7b7d9220 ("modules: Use vmalloc special flag")
Reported-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Tested-on: sun50i-h6-pine-h64
Tested-on: imx8mn-ddr4-evk
Tested-on: sun50i-a64-bananapi-m64
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
To perform partial reads, callers of kernel_read_file*() must have a
non-NULL file_size argument and a preallocated buffer. The new "offset"
argument can then be used to seek to specific locations in the file to
fill the buffer to, at most, "buf_size" per call.
Where possible, the LSM hooks can report whether a full file has been
read or not so that the contents can be reasoned about.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201002173828.2099543-14-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that there is an API for checking loaded contents for modules
loaded without a file, call into the LSM hooks.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: KP Singh <kpsingh@google.com>
Acked-by: Jessica Yu <jeyu@kernel.org>
Link: https://lore.kernel.org/r/20201002173828.2099543-11-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are a few places in the kernel where LSMs would like to have
visibility into the contents of a kernel buffer that has been loaded or
read. While security_kernel_post_read_file() (which includes the
buffer) exists as a pairing for security_kernel_read_file(), no such
hook exists to pair with security_kernel_load_data().
Earlier proposals for just using security_kernel_post_read_file() with a
NULL file argument were rejected (i.e. "file" should always be valid for
the security_..._file hooks, but it appears at least one case was
left in the kernel during earlier refactoring. (This will be fixed in
a subsequent patch.)
Since not all cases of security_kernel_load_data() can have a single
contiguous buffer made available to the LSM hook (e.g. kexec image
segments are separately loaded), there needs to be a way for the LSM to
reason about its expectations of the hook coverage. In order to handle
this, add a "contents" argument to the "kernel_load_data" hook that
indicates if the newly added "kernel_post_load_data" hook will be called
with the full contents once loaded. That way, LSMs requiring full contents
can choose to unilaterally reject "kernel_load_data" with contents=false
(which is effectively the existing hook coverage), but when contents=true
they can allow it and later evaluate the "kernel_post_load_data" hook
once the buffer is loaded.
With this change, LSMs can gain coverage over non-file-backed data loads
(e.g. init_module(2) and firmware userspace helper), which will happen
in subsequent patches.
Additionally prepare IMA to start processing these cases.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: KP Singh <kpsingh@google.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In preparation for adding partial read support, add an optional output
argument to kernel_read_file*() that reports the file size so callers
can reason more easily about their reading progress.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-8-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In preparation for refactoring kernel_read_file*(), remove the redundant
"size" argument which is not needed: it can be included in the return
code, with callers adjusted. (VFS reads already cannot be larger than
INT_MAX.)
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-6-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move kernel_read_file* out of linux/fs.h to its own linux/kernel_read_file.h
include file. That header gets pulled in just about everywhere
and doesn't really need functions not related to the general fs interface.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Link: https://lore.kernel.org/r/20200706232309.12010-2-scott.branden@broadcom.com
Link: https://lore.kernel.org/r/20201002173828.2099543-4-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
FIRMWARE_PREALLOC_BUFFER is a "how", not a "what", and confuses the LSMs
that are interested in filtering between types of things. The "how"
should be an internal detail made uninteresting to the LSMs.
Fixes: a098ecd2fa ("firmware: support loading into a pre-allocated buffer")
Fixes: fd90bc559b ("ima: based on policy verify firmware signatures (pre-allocated buffer)")
Fixes: 4f0496d8ff ("ima: based on policy warn about loading firmware (pre-allocated buffer)")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201002173828.2099543-2-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When kernel module loading failed, user space only get one of the
following error messages:
- ENOEXEC
This is the most confusing one. From corrupted ELF header to bad
WRITE|EXEC flags check introduced by in module_enforce_rwx_sections()
all returns this error number.
- EPERM
This is for blacklisted modules. But mod doesn't do extra explain
on this error either.
- ENOMEM
The only error which needs no explain.
This means, if a user got "Exec format error" from modprobe, it provides
no meaningful way for the user to debug, and will take extra time
communicating to get extra info.
So this patch will add extra error messages for -ENOEXEC and -EPERM
errors, allowing user to do better debugging and reporting.
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Add infrastructure for an arch-specific CONFIG_HAVE_STATIC_CALL_INLINE
option, which is a faster version of CONFIG_HAVE_STATIC_CALL. At
runtime, the static call sites are patched directly, rather than using
the out-of-line trampolines.
Compared to out-of-line static calls, the performance benefits are more
modest, but still measurable. Steven Rostedt did some tracepoint
measurements:
https://lkml.kernel.org/r/20181126155405.72b4f718@gandalf.local.home
This code is heavily inspired by the jump label code (aka "static
jumps"), as some of the concepts are very similar.
For more details, see the comments in include/linux/static_call.h.
[peterz: simplified interface; merged trampolines]
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135804.684334440@infradead.org
Now that notifiers got unbroken; use the proper interface to handle
notifier errors and propagate them.
There were already MODULE_STATE_COMING notifiers that failed; notably:
- jump_label_module_notifier()
- tracepoint_module_notify()
- bpf_event_notify()
By propagating this error, we fix those users.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Jessica Yu <jeyu@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20200818135804.444372853@infradead.org
Summary of modules changes for the 5.9 merge window:
- Have modules that use symbols from proprietary modules inherit the
TAINT_PROPRIETARY_MODULE taint, in an effort to prevent GPL shim modules that
are used to circumvent _GPL exports. These are modules that claim to be GPL
licensed while also using symbols from proprietary modules. Such modules will
be rejected while non-GPL modules will inherit the proprietary taint.
- Module export space cleanup. Unexport symbols that are unused outside of
module.c or otherwise used in only built-in code.
Signed-off-by: Jessica Yu <jeyu@kernel.org>
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Merge tag 'modules-for-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux
Pull module updates from Jessica Yu:
"The most important change would be Christoph Hellwig's patch
implementing proprietary taint inheritance, in an effort to discourage
the creation of GPL "shim" modules that interface between GPL symbols
and proprietary symbols.
Summary:
- Have modules that use symbols from proprietary modules inherit the
TAINT_PROPRIETARY_MODULE taint, in an effort to prevent GPL shim
modules that are used to circumvent _GPL exports. These are modules
that claim to be GPL licensed while also using symbols from
proprietary modules. Such modules will be rejected while non-GPL
modules will inherit the proprietary taint.
- Module export space cleanup. Unexport symbols that are unused
outside of module.c or otherwise used in only built-in code"
* tag 'modules-for-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
modules: inherit TAINT_PROPRIETARY_MODULE
modules: return licensing information from find_symbol
modules: rename the licence field in struct symsearch to license
modules: unexport __module_address
modules: unexport __module_text_address
modules: mark each_symbol_section static
modules: mark find_symbol static
modules: mark ref_module static
modules: linux/moduleparam.h: drop duplicated word in a comment
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Merge tag 'kallsyms_show_value-fix-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull sysfs module section fix from Kees Cook:
"Fix sysfs module section output overflow.
About a month after my kallsyms_show_value() refactoring landed, 0day
noticed that there was a path through the kernfs binattr read handlers
that did not have PAGE_SIZEd buffers, and the module "sections" read
handler made a bad assumption about this, resulting in it stomping on
memory when reached through small-sized splice() calls.
I've added a set of tests to find these kinds of regressions more
quickly in the future as well"
Sefltests-acked-by: Shuah Khan <skhan@linuxfoundation.org>
* tag 'kallsyms_show_value-fix-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
selftests: splice: Check behavior of full and short splices
module: Correctly truncate sysfs sections output
The only-root-readable /sys/module/$module/sections/$section files
did not truncate their output to the available buffer size. While most
paths into the kernfs read handlers end up using PAGE_SIZE buffers,
it's possible to get there through other paths (e.g. splice, sendfile).
Actually limit the output to the "count" passed into the read function,
and report it back correctly. *sigh*
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/20200805002015.GE23458@shao2-debian
Fixes: ed66f991bb ("module: Refactor section attr into bin attribute")
Cc: stable@vger.kernel.org
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
If a TAINT_PROPRIETARY_MODULE exports symbol, inherit the taint flag
for all modules importing these symbols, and don't allow loading
symbols from TAINT_PROPRIETARY_MODULE modules if the module previously
imported gplonly symbols. Add a anti-circumvention devices so people
don't accidentally get themselves into trouble this way.
Comment from Greg:
"Ah, the proven-to-be-illegal "GPL Condom" defense :)"
[jeyu: pr_info -> pr_err and pr_warn as per discussion]
Link: http://lore.kernel.org/r/20200730162957.GA22469@lst.de
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
