Sometimes we would like to revert a particular fix. Currently, this
is not easy because we want to keep all other fixes active and we
could revert only the last applied patch.
One solution would be to apply new patch that implemented all
the reverted functions like in the original code. It would work
as expected but there will be unnecessary redirections. In addition,
it would also require knowing which functions need to be reverted at
build time.
Another problem is when there are many patches that touch the same
functions. There might be dependencies between patches that are
not enforced on the kernel side. Also it might be pretty hard to
actually prepare the patch and ensure compatibility with the other
patches.
Atomic replace && cumulative patches:
A better solution would be to create cumulative patch and say that
it replaces all older ones.
This patch adds a new "replace" flag to struct klp_patch. When it is
enabled, a set of 'nop' klp_func will be dynamically created for all
functions that are already being patched but that will no longer be
modified by the new patch. They are used as a new target during
the patch transition.
The idea is to handle Nops' structures like the static ones. When
the dynamic structures are allocated, we initialize all values that
are normally statically defined.
The only exception is "new_func" in struct klp_func. It has to point
to the original function and the address is known only when the object
(module) is loaded. Note that we really need to set it. The address is
used, for example, in klp_check_stack_func().
Nevertheless we still need to distinguish the dynamically allocated
structures in some operations. For this, we add "nop" flag into
struct klp_func and "dynamic" flag into struct klp_object. They
need special handling in the following situations:
+ The structures are added into the lists of objects and functions
immediately. In fact, the lists were created for this purpose.
+ The address of the original function is known only when the patched
object (module) is loaded. Therefore it is copied later in
klp_init_object_loaded().
+ The ftrace handler must not set PC to func->new_func. It would cause
infinite loop because the address points back to the beginning of
the original function.
+ The various free() functions must free the structure itself.
Note that other ways to detect the dynamic structures are not considered
safe. For example, even the statically defined struct klp_object might
include empty funcs array. It might be there just to run some callbacks.
Also note that the safe iterator must be used in the free() functions.
Otherwise already freed structures might get accessed.
Special callbacks handling:
The callbacks from the replaced patches are _not_ called by intention.
It would be pretty hard to define a reasonable semantic and implement it.
It might even be counter-productive. The new patch is cumulative. It is
supposed to include most of the changes from older patches. In most cases,
it will not want to call pre_unpatch() post_unpatch() callbacks from
the replaced patches. It would disable/break things for no good reasons.
Also it should be easier to handle various scenarios in a single script
in the new patch than think about interactions caused by running many
scripts from older patches. Not to say that the old scripts even would
not expect to be called in this situation.
Removing replaced patches:
One nice effect of the cumulative patches is that the code from the
older patches is no longer used. Therefore the replaced patches can
be removed. It has several advantages:
+ Nops' structs will no longer be necessary and might be removed.
This would save memory, restore performance (no ftrace handler),
allow clear view on what is really patched.
+ Disabling the patch will cause using the original code everywhere.
Therefore the livepatch callbacks could handle only one scenario.
Note that the complication is already complex enough when the patch
gets enabled. It is currently solved by calling callbacks only from
the new cumulative patch.
+ The state is clean in both the sysfs interface and lsmod. The modules
with the replaced livepatches might even get removed from the system.
Some people actually expected this behavior from the beginning. After all
a cumulative patch is supposed to "completely" replace an existing one.
It is like when a new version of an application replaces an older one.
This patch does the first step. It removes the replaced patches from
the list of patches. It is safe. The consistency model ensures that
they are no longer used. By other words, each process works only with
the structures from klp_transition_patch.
The removal is done by a special function. It combines actions done by
__disable_patch() and klp_complete_transition(). But it is a fast
track without all the transaction-related stuff.
Signed-off-by: Jason Baron <jbaron@akamai.com>
[pmladek@suse.com: Split, reuse existing code, simplified]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Currently klp_patch contains a pointer to a statically allocated array of
struct klp_object and struct klp_objects contains a pointer to a statically
allocated array of klp_func. In order to allow for the dynamic allocation
of objects and functions, link klp_patch, klp_object, and klp_func together
via linked lists. This allows us to more easily allocate new objects and
functions, while having the iterator be a simple linked list walk.
The static structures are added to the lists early. It allows to add
the dynamically allocated objects before klp_init_object() and
klp_init_func() calls. Therefore it reduces the further changes
to the code.
This patch does not change the existing behavior.
Signed-off-by: Jason Baron <jbaron@akamai.com>
[pmladek@suse.com: Initialize lists before init calls]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
The possibility to re-enable a registered patch was useful for immediate
patches where the livepatch module had to stay until the system reboot.
The improved consistency model allows to achieve the same result by
unloading and loading the livepatch module again.
Also we are going to add a feature called atomic replace. It will allow
to create a patch that would replace all already registered patches.
The aim is to handle dependent patches more securely. It will obsolete
the stack of patches that helped to handle the dependencies so far.
Then it might be unclear when a cumulative patch re-enabling is safe.
It would be complicated to support the many modes. Instead we could
actually make the API and code easier to understand.
Therefore, remove the two step public API. All the checks and init calls
are moved from klp_register_patch() to klp_enabled_patch(). Also the patch
is automatically freed, including the sysfs interface when the transition
to the disabled state is completed.
As a result, there is never a disabled patch on the top of the stack.
Therefore we do not need to check the stack in __klp_enable_patch().
And we could simplify the check in __klp_disable_patch().
Also the API and logic is much easier. It is enough to call
klp_enable_patch() in module_init() call. The patch can be disabled
by writing '0' into /sys/kernel/livepatch/<patch>/enabled. Then the module
can be removed once the transition finishes and sysfs interface is freed.
The only problem is how to free the structures and kobjects safely.
The operation is triggered from the sysfs interface. We could not put
the related kobject from there because it would cause lock inversion
between klp_mutex and kernfs locks, see kn->count lockdep map.
Therefore, offload the free task to a workqueue. It is perfectly fine:
+ The patch can no longer be used in the livepatch operations.
+ The module could not be removed until the free operation finishes
and module_put() is called.
+ The operation is asynchronous already when the first
klp_try_complete_transition() fails and another call
is queued with a delay.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
module_put() is currently never called in klp_complete_transition() when
klp_force is set. As a result, we might keep the reference count even when
klp_enable_patch() fails and klp_cancel_transition() is called.
This might give the impression that a module might get blocked in some
strange init state. Fortunately, it is not the case. The reference count
is ignored when mod->init fails and erroneous modules are always removed.
Anyway, this might be confusing. Instead, this patch moves
the global klp_forced flag into struct klp_patch. As a result,
we block only modules that might still be in use after a forced
transition. Newly loaded livepatches might be eventually completely
removed later.
It is not a big deal. But the code is at least consistent with
the reality.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
The code for freeing livepatch structures is a bit scattered and tricky:
+ direct calls to klp_free_*_limited() and kobject_put() are
used to release partially initialized objects
+ klp_free_patch() removes the patch from the public list
and releases all objects except for patch->kobj
+ object_put(&patch->kobj) and the related wait_for_completion()
are called directly outside klp_mutex; this code is duplicated;
Now, we are going to remove the registration stage to simplify the API
and the code. This would require handling more situations in
klp_enable_patch() error paths.
More importantly, we are going to add a feature called atomic replace.
It will need to dynamically create func and object structures. We will
want to reuse the existing init() and free() functions. This would
create even more error path scenarios.
This patch implements more straightforward free functions:
+ checks kobj_added flag instead of @limit[*]
+ initializes patch->list early so that the check for empty list
always works
+ The action(s) that has to be done outside klp_mutex are done
in separate klp_free_patch_finish() function. It waits only
when patch->kobj was really released via the _start() part.
The patch does not change the existing behavior.
[*] We need our own flag to track that the kobject was successfully
added to the hierarchy. Note that kobj.state_initialized only
indicates that kobject has been initialized, not whether is has
been added (and needs to be removed on cleanup).
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Jason Baron <jbaron@akamai.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
The address of the to be patched function and new function is stored
in struct klp_func as:
void *new_func;
unsigned long old_addr;
The different naming scheme and type are derived from the way
the addresses are set. @old_addr is assigned at runtime using
kallsyms-based search. @new_func is statically initialized,
for example:
static struct klp_func funcs[] = {
{
.old_name = "cmdline_proc_show",
.new_func = livepatch_cmdline_proc_show,
}, { }
};
This patch changes unsigned long old_addr -> void *old_func. It removes
some confusion when these address are later used in the code. It is
motivated by a followup patch that adds special NOP struct klp_func
where we want to assign func->new_func = func->old_addr respectively
func->new_func = func->old_func.
This patch does not modify the existing behavior.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Alice Ferrazzi <alice.ferrazzi@gmail.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Pull vfs mount API prep from Al Viro:
"Mount API prereqs.
Mostly that's LSM mount options cleanups. There are several minor
fixes in there, but nothing earth-shattering (leaks on failure exits,
mostly)"
* 'mount.part1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (27 commits)
mount_fs: suppress MAC on MS_SUBMOUNT as well as MS_KERNMOUNT
smack: rewrite smack_sb_eat_lsm_opts()
smack: get rid of match_token()
smack: take the guts of smack_parse_opts_str() into a new helper
LSM: new method: ->sb_add_mnt_opt()
selinux: rewrite selinux_sb_eat_lsm_opts()
selinux: regularize Opt_... names a bit
selinux: switch away from match_token()
selinux: new helper - selinux_add_opt()
LSM: bury struct security_mnt_opts
smack: switch to private smack_mnt_opts
selinux: switch to private struct selinux_mnt_opts
LSM: hide struct security_mnt_opts from any generic code
selinux: kill selinux_sb_get_mnt_opts()
LSM: turn sb_eat_lsm_opts() into a method
nfs_remount(): don't leak, don't ignore LSM options quietly
btrfs: sanitize security_mnt_opts use
selinux; don't open-code a loop in sb_finish_set_opts()
LSM: split ->sb_set_mnt_opts() out of ->sb_kern_mount()
new helper: security_sb_eat_lsm_opts()
...
Pull trivial vfs updates from Al Viro:
"A few cleanups + Neil's namespace_unlock() optimization"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
exec: make prepare_bprm_creds static
genheaders: %-<width>s had been there since v6; %-*s - since v7
VFS: use synchronize_rcu_expedited() in namespace_unlock()
iov_iter: reduce code duplication
Pull more ARM SoC updates from Olof Johansson:
"A few updates that we merged late but are low risk for regressions for
other platforms (and a few other straggling patches):
- I mis-tagged the 'drivers' branch, and missed 3 patches. Merged in
here. They're for a driver for the PL353 SRAM controller and a
build fix for the qualcomm scm driver.
- A new platform, RDA Micro RDA8810PL (Cortex-A5 w/ integrated
Vivante GPU, 256MB RAM, Wifi). This includes some acked
platform-specific drivers (serial, etc). This also include DTs for
two boards with this SoC, OrangePi 2G and OrangePi i86.
- i.MX8 is another new platform (NXP, 4x Cortex-A53 + Cortex-M4, 4K
video playback offload). This is the first i.MX 64-bit SoC.
- Some minor updates to Samsung boards (adding a few peripherals in
DTs).
- Small rework for SMP bootup on STi platforms.
- A couple of TEE driver fixes.
- A couple of new config options (bcm2835 thermal, Uniphier MDMAC)
enabled in defconfigs"
* tag 'armsoc-late' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (27 commits)
ARM: multi_v7_defconfig: enable CONFIG_UNIPHIER_MDMAC
arm64: defconfig: Re-enable bcm2835-thermal driver
MAINTAINERS: Add entry for RDA Micro SoC architecture
tty: serial: Add RDA8810PL UART driver
ARM: dts: rda8810pl: Add interrupt support for UART
dt-bindings: serial: Document RDA Micro UART
ARM: dts: rda8810pl: Add timer support
ARM: dts: Add devicetree for OrangePi i96 board
ARM: dts: Add devicetree for OrangePi 2G IoT board
ARM: dts: Add devicetree for RDA8810PL SoC
ARM: Prepare RDA8810PL SoC
dt-bindings: arm: Document RDA8810PL and reference boards
dt-bindings: Add RDA Micro vendor prefix
ARM: sti: remove pen_release and boot_lock
arm64: dts: exynos: Add Bluetooth chip to TM2(e) boards
arm64: dts: imx8mq-evk: enable watchdog
arm64: dts: imx8mq: add watchdog devices
MAINTAINERS: add i.MX8 DT path to i.MX architecture
arm64: add support for i.MX8M EVK board
arm64: add basic DTS for i.MX8MQ
...
Merge more updates from Andrew Morton:
- procfs updates
- various misc bits
- lib/ updates
- epoll updates
- autofs
- fatfs
- a few more MM bits
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (58 commits)
mm/page_io.c: fix polled swap page in
checkpatch: add Co-developed-by to signature tags
docs: fix Co-Developed-by docs
drivers/base/platform.c: kmemleak ignore a known leak
fs: don't open code lru_to_page()
fs/: remove caller signal_pending branch predictions
mm/: remove caller signal_pending branch predictions
arch/arc/mm/fault.c: remove caller signal_pending_branch predictions
kernel/sched/: remove caller signal_pending branch predictions
kernel/locking/mutex.c: remove caller signal_pending branch predictions
mm: select HAVE_MOVE_PMD on x86 for faster mremap
mm: speed up mremap by 20x on large regions
mm: treewide: remove unused address argument from pte_alloc functions
initramfs: cleanup incomplete rootfs
scripts/gdb: fix lx-version string output
kernel/kcov.c: mark write_comp_data() as notrace
kernel/sysctl: add panic_print into sysctl
panic: add options to print system info when panic happens
bfs: extra sanity checking and static inode bitmap
exec: separate MM_ANONPAGES and RLIMIT_STACK accounting
...
Merge in a few missing patches from the pull request (my copy of the
branch was behind the staged version in linux-next).
* next/drivers:
memory: pl353: Add driver for arm pl353 static memory controller
dt-bindings: memory: Add pl353 smc controller devicetree binding information
firmware: qcom: scm: fix compilation error when disabled
Signed-off-by: Olof Johansson <olof@lixom.net>
Patch series "Add support for fast mremap".
This series speeds up the mremap(2) syscall by copying page tables at
the PMD level even for non-THP systems. There is concern that the extra
'address' argument that mremap passes to pte_alloc may do something
subtle architecture related in the future that may make the scheme not
work. Also we find that there is no point in passing the 'address' to
pte_alloc since its unused. This patch therefore removes this argument
tree-wide resulting in a nice negative diff as well. Also ensuring
along the way that the enabled architectures do not do anything funky
with the 'address' argument that goes unnoticed by the optimization.
Build and boot tested on x86-64. Build tested on arm64. The config
enablement patch for arm64 will be posted in the future after more
testing.
The changes were obtained by applying the following Coccinelle script.
(thanks Julia for answering all Coccinelle questions!).
Following fix ups were done manually:
* Removal of address argument from pte_fragment_alloc
* Removal of pte_alloc_one_fast definitions from m68k and microblaze.
// Options: --include-headers --no-includes
// Note: I split the 'identifier fn' line, so if you are manually
// running it, please unsplit it so it runs for you.
virtual patch
@pte_alloc_func_def depends on patch exists@
identifier E2;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
type T2;
@@
fn(...
- , T2 E2
)
{ ... }
@pte_alloc_func_proto_noarg depends on patch exists@
type T1, T2, T3, T4;
identifier fn =~ "^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
(
- T3 fn(T1, T2);
+ T3 fn(T1);
|
- T3 fn(T1, T2, T4);
+ T3 fn(T1, T2);
)
@pte_alloc_func_proto depends on patch exists@
identifier E1, E2, E4;
type T1, T2, T3, T4;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
(
- T3 fn(T1 E1, T2 E2);
+ T3 fn(T1 E1);
|
- T3 fn(T1 E1, T2 E2, T4 E4);
+ T3 fn(T1 E1, T2 E2);
)
@pte_alloc_func_call depends on patch exists@
expression E2;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
fn(...
-, E2
)
@pte_alloc_macro depends on patch exists@
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
identifier a, b, c;
expression e;
position p;
@@
(
- #define fn(a, b, c) e
+ #define fn(a, b) e
|
- #define fn(a, b) e
+ #define fn(a) e
)
Link: http://lkml.kernel.org/r/20181108181201.88826-2-joelaf@google.com
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Suggested-by: Kirill A. Shutemov <kirill@shutemov.name>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
get_arg_page() checks bprm->rlim_stack.rlim_cur and re-calculates the
"extra" size for argv/envp pointers every time, this is a bit ugly and
even not strictly correct: acct_arg_size() must not account this size.
Remove all the rlimit code in get_arg_page(). Instead, add bprm->argmin
calculated once at the start of __do_execve_file() and change
copy_strings to check bprm->p >= bprm->argmin.
The patch adds the new helper, prepare_arg_pages() which initializes
bprm->argc/envc and bprm->argmin.
[oleg@redhat.com: fix !CONFIG_MMU version of get_arg_page()]
Link: http://lkml.kernel.org/r/20181126122307.GA1660@redhat.com
[akpm@linux-foundation.org: use max_t]
Link: http://lkml.kernel.org/r/20181112160910.GA28440@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 092a53452b ("autofs: take more care to not update last_used on
path walk") helped to (partially) resolve a problem where automounts
were not expiring due to aggressive accesses from user space.
This patch was later reverted because, for very large environments, it
meant more mount requests from clients and when there are a lot of
clients this caused a fairly significant increase in server load.
But there is a need for both types of expire check, depending on use
case, so add a mount option to allow for strict update of last use of
autofs dentrys (which just means not updating the last use on path walk
access).
Link: http://lkml.kernel.org/r/154296973880.9889.14085372741514507967.stgit@pluto-themaw-net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
gen_pool_alloc_algo() uses different allocation functions implementing
different allocation algorithms. With gen_pool_first_fit_align()
allocation function, the returned address should be aligned on the
requested boundary.
If chunk start address isn't aligned on the requested boundary, the
returned address isn't aligned too. The only way to get properly
aligned address is to initialize the pool with chunks aligned on the
requested boundary. If want to have an ability to allocate buffers
aligned on different boundaries (for example, 4K, 1MB, ...), the chunk
start address should be aligned on the max possible alignment.
This happens because gen_pool_first_fit_align() looks for properly
aligned memory block without taking into account the chunk start address
alignment.
To fix this, we provide chunk start address to
gen_pool_first_fit_align() and change its implementation such that it
starts looking for properly aligned block with appropriate offset
(exactly as is done in CMA).
Link: https://lkml.kernel.org/lkml/a170cf65-6884-3592-1de9-4c235888cc8a@intel.com
Link: http://lkml.kernel.org/r/1541690953-4623-1-git-send-email-alexey.skidanov@intel.com
Signed-off-by: Alexey Skidanov <alexey.skidanov@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Daniel Mentz <danielmentz@google.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Laura Abbott <labbott@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The introduction of these dummy BUILD_BUG_ON stubs dates back to commmit
903c0c7cdc ("sparse: define dummy BUILD_BUG_ON definition for
sparse").
At that time, BUILD_BUG_ON() was implemented with the negative array
trick *and* the link-time trick, like this:
extern int __build_bug_on_failed;
#define BUILD_BUG_ON(condition) \
do { \
((void)sizeof(char[1 - 2*!!(condition)])); \
if (condition) __build_bug_on_failed = 1; \
} while(0)
Sparse is more strict about the negative array trick than GCC because
Sparse requires the array length to be really constant.
Here is the simple test code for the macro above:
static const int x = 0;
BUILD_BUG_ON(x);
GCC is absolutely fine with it (-Wvla was enabled only very recently),
but Sparse warns like this:
error: bad constant expression
error: cannot size expression
(If you are using a newer version of Sparse, you will see a different
warning message, "warning: Variable length array is used".)
Anyway, Sparse was producing many false positives, and noisier than it
should be at that time.
With the previous commit, the leftover negative array trick is gone.
Sparse is fine with the current BUILD_BUG_ON(), which is implemented by
using the 'error' attribute.
I am keeping the stub for BUILD_BUG_ON_ZERO(). Otherwise, Sparse would
complain about the following code, which GCC is fine with:
static const int x = 0;
int y = BUILD_BUG_ON_ZERO(x);
Link: http://lkml.kernel.org/r/1542856462-18836-3-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Originally, the rule used to be that you'd have to do access_ok()
separately, and then user_access_begin() before actually doing the
direct (optimized) user access.
But experience has shown that people then decide not to do access_ok()
at all, and instead rely on it being implied by other operations or
similar. Which makes it very hard to verify that the access has
actually been range-checked.
If you use the unsafe direct user accesses, hardware features (either
SMAP - Supervisor Mode Access Protection - on x86, or PAN - Privileged
Access Never - on ARM) do force you to use user_access_begin(). But
nothing really forces the range check.
By putting the range check into user_access_begin(), we actually force
people to do the right thing (tm), and the range check vill be visible
near the actual accesses. We have way too long a history of people
trying to avoid them.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.
It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access. But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.
A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model. And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.
This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.
There were a couple of notable cases:
- csky still had the old "verify_area()" name as an alias.
- the iter_iov code had magical hardcoded knowledge of the actual
values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
really used it)
- microblaze used the type argument for a debug printout
but other than those oddities this should be a total no-op patch.
I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something. Any missed conversion should be trivially fixable, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull networking fixes from David Miller:
"Several fixes here. Basically split down the line between newly
introduced regressions and long existing problems:
1) Double free in tipc_enable_bearer(), from Cong Wang.
2) Many fixes to nf_conncount, from Florian Westphal.
3) op->get_regs_len() can throw an error, check it, from Yunsheng
Lin.
4) Need to use GFP_ATOMIC in *_add_hash_mac_address() of fsl/fman
driver, from Scott Wood.
5) Inifnite loop in fib_empty_table(), from Yue Haibing.
6) Use after free in ax25_fillin_cb(), from Cong Wang.
7) Fix socket locking in nr_find_socket(), also from Cong Wang.
8) Fix WoL wakeup enable in r8169, from Heiner Kallweit.
9) On 32-bit sock->sk_stamp is not thread-safe, from Deepa Dinamani.
10) Fix ptr_ring wrap during queue swap, from Cong Wang.
11) Missing shutdown callback in hinic driver, from Xue Chaojing.
12) Need to return NULL on error from ip6_neigh_lookup(), from Stefano
Brivio.
13) BPF out of bounds speculation fixes from Daniel Borkmann"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (57 commits)
ipv6: Consider sk_bound_dev_if when binding a socket to an address
ipv6: Fix dump of specific table with strict checking
bpf: add various test cases to selftests
bpf: prevent out of bounds speculation on pointer arithmetic
bpf: fix check_map_access smin_value test when pointer contains offset
bpf: restrict unknown scalars of mixed signed bounds for unprivileged
bpf: restrict stack pointer arithmetic for unprivileged
bpf: restrict map value pointer arithmetic for unprivileged
bpf: enable access to ax register also from verifier rewrite
bpf: move tmp variable into ax register in interpreter
bpf: move {prev_,}insn_idx into verifier env
isdn: fix kernel-infoleak in capi_unlocked_ioctl
ipv6: route: Fix return value of ip6_neigh_lookup() on neigh_create() error
net/hamradio/6pack: use mod_timer() to rearm timers
net-next/hinic:add shutdown callback
net: hns3: call hns3_nic_net_open() while doing HNAE3_UP_CLIENT
ip: validate header length on virtual device xmit
tap: call skb_probe_transport_header after setting skb->dev
ptr_ring: wrap back ->producer in __ptr_ring_swap_queue()
net: rds: remove unnecessary NULL check
...
Pull input updates from Dmitry Torokhov:
"A tiny pull request this merge window unfortunately, should get more
material in for the next release:
- new driver for Raspberry Pi's touchscreen (firmware interface)
- miscellaneous input driver fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: elan_i2c - add ACPI ID for touchpad in ASUS Aspire F5-573G
Input: atmel_mxt_ts - don't try to free unallocated kernel memory
Input: drv2667 - fix indentation issues
Input: touchscreen - fix coding style issue
Input: add official Raspberry Pi's touchscreen driver
Input: nomadik-ske-keypad - fix a loop timeout test
Input: rotary-encoder - don't log EPROBE_DEFER to kernel log
Input: olpc_apsp - remove set but not used variable 'np'
Input: olpc_apsp - enable the SP clock
Input: olpc_apsp - check FIFO status on open(), not probe()
Input: olpc_apsp - drop CONFIG_OLPC dependency
clk: mmp2: add SP clock
dt-bindings: marvell,mmp2: Add clock id for the SP clock
Input: ad7879 - drop platform data support
Pull virtio/vhost updates from Michael Tsirkin:
"Features, fixes, cleanups:
- discard in virtio blk
- misc fixes and cleanups"
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
vhost: correct the related warning message
vhost: split structs into a separate header file
virtio: remove deprecated VIRTIO_PCI_CONFIG()
vhost/vsock: switch to a mutex for vhost_vsock_hash
virtio_blk: add discard and write zeroes support
Pull more block updates from Jens Axboe:
- Dead code removal for loop/sunvdc (Chengguang)
- Mark BIDI support for bsg as deprecated, logging a single dmesg
warning if anyone is actually using it (Christoph)
- blkcg cleanup, killing a dead function and making the tryget_closest
variant easier to read (Dennis)
- Floppy fixes, one fixing a regression in swim3 (Finn)
- lightnvm use-after-free fix (Gustavo)
- gdrom leak fix (Wenwen)
- a set of drbd updates (Lars, Luc, Nathan, Roland)
* tag 'for-4.21/block-20190102' of git://git.kernel.dk/linux-block: (28 commits)
block/swim3: Fix regression on PowerBook G3
block/swim3: Fix -EBUSY error when re-opening device after unmount
block/swim3: Remove dead return statement
block/amiflop: Don't log error message on invalid ioctl
gdrom: fix a memory leak bug
lightnvm: pblk: fix use-after-free bug
block: sunvdc: remove redundant code
block: loop: remove redundant code
bsg: deprecate BIDI support in bsg
blkcg: remove unused __blkg_release_rcu()
blkcg: clean up blkg_tryget_closest()
drbd: Change drbd_request_detach_interruptible's return type to int
drbd: Avoid Clang warning about pointless switch statment
drbd: introduce P_ZEROES (REQ_OP_WRITE_ZEROES on the "wire")
drbd: skip spurious timeout (ping-timeo) when failing promote
drbd: don't retry connection if peers do not agree on "authentication" settings
drbd: fix print_st_err()'s prototype to match the definition
drbd: avoid spurious self-outdating with concurrent disconnect / down
drbd: do not block when adjusting "disk-options" while IO is frozen
drbd: fix comment typos
...
Pull more clk updates from Stephen Boyd:
"One more patch to generalize a set of DT binding defines now before
-rc1 comes out.
This way the SoC DTS files can use the proper defines from a stable
tag"
* tag 'clk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
clk: imx8qxp: make the name of clock ID generic
Pull mailbox updates from Jassi Brar:
- Introduce device-managed registration
devm_mbox_controller_un/register and convert drivers to use it
- Introduce flush api to support clients that must busy-wait in atomic
context
- Support multiple controllers per device
- Hi3660: a bugfix and constify ops structure
- TI-MsgMgr: off by one bugfix.
- BCM: switch to spdx license
- Tegra-HSP: support for shared mailboxes and suspend/resume.
* tag 'mailbox-v4.21' of git://git.linaro.org/landing-teams/working/fujitsu/integration: (30 commits)
mailbox: tegra-hsp: Use device-managed registration API
mailbox: tegra-hsp: use devm_kstrdup_const()
mailbox: tegra-hsp: Add suspend/resume support
mailbox: tegra-hsp: Add support for shared mailboxes
dt-bindings: tegra186-hsp: Add shared mailboxes
mailbox: Allow multiple controllers per device
mailbox: Support blocking transfers in atomic context
mailbox: ti-msgmgr: Use device-managed registration API
mailbox: stm32-ipcc: Use device-managed registration API
mailbox: rockchip: Use device-managed registration API
mailbox: qcom-apcs: Use device-managed registration API
mailbox: platform-mhu: Use device-managed registration API
mailbox: omap: Use device-managed registration API
mailbox: mtk-cmdq: Remove needless devm_kfree() calls
mailbox: mtk-cmdq: Use device-managed registration API
mailbox: xgene-slimpro: Use device-managed registration API
mailbox: sti: Use device-managed registration API
mailbox: altera: Use device-managed registration API
mailbox: imx: Use device-managed registration API
mailbox: hi6220: Use device-managed registration API
...
Alexei Starovoitov says:
====================
pull-request: bpf 2019-01-02
The following pull-request contains BPF updates for your *net* tree.
The main changes are:
1) prevent out of bounds speculation on pointer arithmetic, from Daniel.
2) typo fix, from Xiaozhou.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull NFS client updates from Anna Schumaker:
"Stable bugfixes:
- xprtrdma: Yet another double DMA-unmap # v4.20
Features:
- Allow some /proc/sys/sunrpc entries without CONFIG_SUNRPC_DEBUG
- Per-xprt rdma receive workqueues
- Drop support for FMR memory registration
- Make port= mount option optional for RDMA mounts
Other bugfixes and cleanups:
- Remove unused nfs4_xdev_fs_type declaration
- Fix comments for behavior that has changed
- Remove generic RPC credentials by switching to 'struct cred'
- Fix crossing mountpoints with different auth flavors
- Various xprtrdma fixes from testing and auditing the close code
- Fixes for disconnect issues when using xprtrdma with krb5
- Clean up and improve xprtrdma trace points
- Fix NFS v4.2 async copy reboot recovery"
* tag 'nfs-for-4.21-1' of git://git.linux-nfs.org/projects/anna/linux-nfs: (63 commits)
sunrpc: convert to DEFINE_SHOW_ATTRIBUTE
sunrpc: Add xprt after nfs4_test_session_trunk()
sunrpc: convert unnecessary GFP_ATOMIC to GFP_NOFS
sunrpc: handle ENOMEM in rpcb_getport_async
NFS: remove unnecessary test for IS_ERR(cred)
xprtrdma: Prevent leak of rpcrdma_rep objects
NFSv4.2 fix async copy reboot recovery
xprtrdma: Don't leak freed MRs
xprtrdma: Add documenting comment for rpcrdma_buffer_destroy
xprtrdma: Replace outdated comment for rpcrdma_ep_post
xprtrdma: Update comments in frwr_op_send
SUNRPC: Fix some kernel doc complaints
SUNRPC: Simplify defining common RPC trace events
NFS: Fix NFSv4 symbolic trace point output
xprtrdma: Trace mapping, alloc, and dereg failures
xprtrdma: Add trace points for calls to transport switch methods
xprtrdma: Relocate the xprtrdma_mr_map trace points
xprtrdma: Clean up of xprtrdma chunk trace points
xprtrdma: Remove unused fields from rpcrdma_ia
xprtrdma: Cull dprintk() call sites
...
Pull nfsd updates from Bruce Fields:
"Thanks to Vasily Averin for fixing a use-after-free in the
containerized NFSv4.2 client, and cleaning up some convoluted
backchannel server code in the process.
Otherwise, miscellaneous smaller bugfixes and cleanup"
* tag 'nfsd-4.21' of git://linux-nfs.org/~bfields/linux: (25 commits)
nfs: fixed broken compilation in nfs_callback_up_net()
nfs: minor typo in nfs4_callback_up_net()
sunrpc: fix debug message in svc_create_xprt()
sunrpc: make visible processing error in bc_svc_process()
sunrpc: remove unused xpo_prep_reply_hdr callback
sunrpc: remove svc_rdma_bc_class
sunrpc: remove svc_tcp_bc_class
sunrpc: remove unused bc_up operation from rpc_xprt_ops
sunrpc: replace svc_serv->sv_bc_xprt by boolean flag
sunrpc: use-after-free in svc_process_common()
sunrpc: use SVC_NET() in svcauth_gss_* functions
nfsd: drop useless LIST_HEAD
lockd: Show pid of lockd for remote locks
NFSD remove OP_CACHEME from 4.2 op_flags
nfsd: Return EPERM, not EACCES, in some SETATTR cases
sunrpc: fix cache_head leak due to queued request
nfsd: clean up indentation, increase indentation in switch statement
svcrdma: Optimize the logic that selects the R_key to invalidate
nfsd: fix a warning in __cld_pipe_upcall()
nfsd4: fix crash on writing v4_end_grace before nfsd startup
...
Jann reported that the original commit back in b2157399cc
("bpf: prevent out-of-bounds speculation") was not sufficient
to stop CPU from speculating out of bounds memory access:
While b2157399cc only focussed on masking array map access
for unprivileged users for tail calls and data access such
that the user provided index gets sanitized from BPF program
and syscall side, there is still a more generic form affected
from BPF programs that applies to most maps that hold user
data in relation to dynamic map access when dealing with
unknown scalars or "slow" known scalars as access offset, for
example:
- Load a map value pointer into R6
- Load an index into R7
- Do a slow computation (e.g. with a memory dependency) that
loads a limit into R8 (e.g. load the limit from a map for
high latency, then mask it to make the verifier happy)
- Exit if R7 >= R8 (mispredicted branch)
- Load R0 = R6[R7]
- Load R0 = R6[R0]
For unknown scalars there are two options in the BPF verifier
where we could derive knowledge from in order to guarantee
safe access to the memory: i) While </>/<=/>= variants won't
allow to derive any lower or upper bounds from the unknown
scalar where it would be safe to add it to the map value
pointer, it is possible through ==/!= test however. ii) another
option is to transform the unknown scalar into a known scalar,
for example, through ALU ops combination such as R &= <imm>
followed by R |= <imm> or any similar combination where the
original information from the unknown scalar would be destroyed
entirely leaving R with a constant. The initial slow load still
precedes the latter ALU ops on that register, so the CPU
executes speculatively from that point. Once we have the known
scalar, any compare operation would work then. A third option
only involving registers with known scalars could be crafted
as described in [0] where a CPU port (e.g. Slow Int unit)
would be filled with many dependent computations such that
the subsequent condition depending on its outcome has to wait
for evaluation on its execution port and thereby executing
speculatively if the speculated code can be scheduled on a
different execution port, or any other form of mistraining
as described in [1], for example. Given this is not limited
to only unknown scalars, not only map but also stack access
is affected since both is accessible for unprivileged users
and could potentially be used for out of bounds access under
speculation.
In order to prevent any of these cases, the verifier is now
sanitizing pointer arithmetic on the offset such that any
out of bounds speculation would be masked in a way where the
pointer arithmetic result in the destination register will
stay unchanged, meaning offset masked into zero similar as
in array_index_nospec() case. With regards to implementation,
there are three options that were considered: i) new insn
for sanitation, ii) push/pop insn and sanitation as inlined
BPF, iii) reuse of ax register and sanitation as inlined BPF.
Option i) has the downside that we end up using from reserved
bits in the opcode space, but also that we would require
each JIT to emit masking as native arch opcodes meaning
mitigation would have slow adoption till everyone implements
it eventually which is counter-productive. Option ii) and iii)
have both in common that a temporary register is needed in
order to implement the sanitation as inlined BPF since we
are not allowed to modify the source register. While a push /
pop insn in ii) would be useful to have in any case, it
requires once again that every JIT needs to implement it
first. While possible, amount of changes needed would also
be unsuitable for a -stable patch. Therefore, the path which
has fewer changes, less BPF instructions for the mitigation
and does not require anything to be changed in the JITs is
option iii) which this work is pursuing. The ax register is
already mapped to a register in all JITs (modulo arm32 where
it's mapped to stack as various other BPF registers there)
and used in constant blinding for JITs-only so far. It can
be reused for verifier rewrites under certain constraints.
The interpreter's tmp "register" has therefore been remapped
into extending the register set with hidden ax register and
reusing that for a number of instructions that needed the
prior temporary variable internally (e.g. div, mod). This
allows for zero increase in stack space usage in the interpreter,
and enables (restricted) generic use in rewrites otherwise as
long as such a patchlet does not make use of these instructions.
The sanitation mask is dynamic and relative to the offset the
map value or stack pointer currently holds.
There are various cases that need to be taken under consideration
for the masking, e.g. such operation could look as follows:
ptr += val or val += ptr or ptr -= val. Thus, the value to be
sanitized could reside either in source or in destination
register, and the limit is different depending on whether
the ALU op is addition or subtraction and depending on the
current known and bounded offset. The limit is derived as
follows: limit := max_value_size - (smin_value + off). For
subtraction: limit := umax_value + off. This holds because
we do not allow any pointer arithmetic that would
temporarily go out of bounds or would have an unknown
value with mixed signed bounds where it is unclear at
verification time whether the actual runtime value would
be either negative or positive. For example, we have a
derived map pointer value with constant offset and bounded
one, so limit based on smin_value works because the verifier
requires that statically analyzed arithmetic on the pointer
must be in bounds, and thus it checks if resulting
smin_value + off and umax_value + off is still within map
value bounds at time of arithmetic in addition to time of
access. Similarly, for the case of stack access we derive
the limit as follows: MAX_BPF_STACK + off for subtraction
and -off for the case of addition where off := ptr_reg->off +
ptr_reg->var_off.value. Subtraction is a special case for
the masking which can be in form of ptr += -val, ptr -= -val,
or ptr -= val. In the first two cases where we know that
the value is negative, we need to temporarily negate the
value in order to do the sanitation on a positive value
where we later swap the ALU op, and restore original source
register if the value was in source.
The sanitation of pointer arithmetic alone is still not fully
sufficient as is, since a scenario like the following could
happen ...
PTR += 0x1000 (e.g. K-based imm)
PTR -= BIG_NUMBER_WITH_SLOW_COMPARISON
PTR += 0x1000
PTR -= BIG_NUMBER_WITH_SLOW_COMPARISON
[...]
... which under speculation could end up as ...
PTR += 0x1000
PTR -= 0 [ truncated by mitigation ]
PTR += 0x1000
PTR -= 0 [ truncated by mitigation ]
[...]
... and therefore still access out of bounds. To prevent such
case, the verifier is also analyzing safety for potential out
of bounds access under speculative execution. Meaning, it is
also simulating pointer access under truncation. We therefore
"branch off" and push the current verification state after the
ALU operation with known 0 to the verification stack for later
analysis. Given the current path analysis succeeded it is
likely that the one under speculation can be pruned. In any
case, it is also subject to existing complexity limits and
therefore anything beyond this point will be rejected. In
terms of pruning, it needs to be ensured that the verification
state from speculative execution simulation must never prune
a non-speculative execution path, therefore, we mark verifier
state accordingly at the time of push_stack(). If verifier
detects out of bounds access under speculative execution from
one of the possible paths that includes a truncation, it will
reject such program.
Given we mask every reg-based pointer arithmetic for
unprivileged programs, we've been looking into how it could
affect real-world programs in terms of size increase. As the
majority of programs are targeted for privileged-only use
case, we've unconditionally enabled masking (with its alu
restrictions on top of it) for privileged programs for the
sake of testing in order to check i) whether they get rejected
in its current form, and ii) by how much the number of
instructions and size will increase. We've tested this by
using Katran, Cilium and test_l4lb from the kernel selftests.
For Katran we've evaluated balancer_kern.o, Cilium bpf_lxc.o
and an older test object bpf_lxc_opt_-DUNKNOWN.o and l4lb
we've used test_l4lb.o as well as test_l4lb_noinline.o. We
found that none of the programs got rejected by the verifier
with this change, and that impact is rather minimal to none.
balancer_kern.o had 13,904 bytes (1,738 insns) xlated and
7,797 bytes JITed before and after the change. Most complex
program in bpf_lxc.o had 30,544 bytes (3,817 insns) xlated
and 18,538 bytes JITed before and after and none of the other
tail call programs in bpf_lxc.o had any changes either. For
the older bpf_lxc_opt_-DUNKNOWN.o object we found a small
increase from 20,616 bytes (2,576 insns) and 12,536 bytes JITed
before to 20,664 bytes (2,582 insns) and 12,558 bytes JITed
after the change. Other programs from that object file had
similar small increase. Both test_l4lb.o had no change and
remained at 6,544 bytes (817 insns) xlated and 3,401 bytes
JITed and for test_l4lb_noinline.o constant at 5,080 bytes
(634 insns) xlated and 3,313 bytes JITed. This can be explained
in that LLVM typically optimizes stack based pointer arithmetic
by using K-based operations and that use of dynamic map access
is not overly frequent. However, in future we may decide to
optimize the algorithm further under known guarantees from
branch and value speculation. Latter seems also unclear in
terms of prediction heuristics that today's CPUs apply as well
as whether there could be collisions in e.g. the predictor's
Value History/Pattern Table for triggering out of bounds access,
thus masking is performed unconditionally at this point but could
be subject to relaxation later on. We were generally also
brainstorming various other approaches for mitigation, but the
blocker was always lack of available registers at runtime and/or
overhead for runtime tracking of limits belonging to a specific
pointer. Thus, we found this to be minimally intrusive under
given constraints.
With that in place, a simple example with sanitized access on
unprivileged load at post-verification time looks as follows:
# bpftool prog dump xlated id 282
[...]
28: (79) r1 = *(u64 *)(r7 +0)
29: (79) r2 = *(u64 *)(r7 +8)
30: (57) r1 &= 15
31: (79) r3 = *(u64 *)(r0 +4608)
32: (57) r3 &= 1
33: (47) r3 |= 1
34: (2d) if r2 > r3 goto pc+19
35: (b4) (u32) r11 = (u32) 20479 |
36: (1f) r11 -= r2 | Dynamic sanitation for pointer
37: (4f) r11 |= r2 | arithmetic with registers
38: (87) r11 = -r11 | containing bounded or known
39: (c7) r11 s>>= 63 | scalars in order to prevent
40: (5f) r11 &= r2 | out of bounds speculation.
41: (0f) r4 += r11 |
42: (71) r4 = *(u8 *)(r4 +0)
43: (6f) r4 <<= r1
[...]
For the case where the scalar sits in the destination register
as opposed to the source register, the following code is emitted
for the above example:
[...]
16: (b4) (u32) r11 = (u32) 20479
17: (1f) r11 -= r2
18: (4f) r11 |= r2
19: (87) r11 = -r11
20: (c7) r11 s>>= 63
21: (5f) r2 &= r11
22: (0f) r2 += r0
23: (61) r0 = *(u32 *)(r2 +0)
[...]
JIT blinding example with non-conflicting use of r10:
[...]
d5: je 0x0000000000000106 _
d7: mov 0x0(%rax),%edi |
da: mov $0xf153246,%r10d | Index load from map value and
e0: xor $0xf153259,%r10 | (const blinded) mask with 0x1f.
e7: and %r10,%rdi |_
ea: mov $0x2f,%r10d |
f0: sub %rdi,%r10 | Sanitized addition. Both use r10
f3: or %rdi,%r10 | but do not interfere with each
f6: neg %r10 | other. (Neither do these instructions
f9: sar $0x3f,%r10 | interfere with the use of ax as temp
fd: and %r10,%rdi | in interpreter.)
100: add %rax,%rdi |_
103: mov 0x0(%rdi),%eax
[...]
Tested that it fixes Jann's reproducer, and also checked that test_verifier
and test_progs suite with interpreter, JIT and JIT with hardening enabled
on x86-64 and arm64 runs successfully.
[0] Speculose: Analyzing the Security Implications of Speculative
Execution in CPUs, Giorgi Maisuradze and Christian Rossow,
https://arxiv.org/pdf/1801.04084.pdf
[1] A Systematic Evaluation of Transient Execution Attacks and
Defenses, Claudio Canella, Jo Van Bulck, Michael Schwarz,
Moritz Lipp, Benjamin von Berg, Philipp Ortner, Frank Piessens,
Dmitry Evtyushkin, Daniel Gruss,
https://arxiv.org/pdf/1811.05441.pdf
Fixes: b2157399cc ("bpf: prevent out-of-bounds speculation")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Right now we are using BPF ax register in JIT for constant blinding as
well as in interpreter as temporary variable. Verifier will not be able
to use it simply because its use will get overridden from the former in
bpf_jit_blind_insn(). However, it can be made to work in that blinding
will be skipped if there is prior use in either source or destination
register on the instruction. Taking constraints of ax into account, the
verifier is then open to use it in rewrites under some constraints. Note,
ax register already has mappings in every eBPF JIT.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This change moves the on-stack 64 bit tmp variable in ___bpf_prog_run()
into the hidden ax register. The latter is currently only used in JITs
for constant blinding as a temporary scratch register, meaning the BPF
interpreter will never see the use of ax. Therefore it is safe to use
it for the cases where tmp has been used earlier. This is needed to later
on allow restricted hidden use of ax in both interpreter and JITs.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move prev_insn_idx and insn_idx from the do_check() function into
the verifier environment, so they can be read inside the various
helper functions for handling the instructions. It's easier to put
this into the environment rather than changing all call-sites only
to pass it along. insn_idx is useful in particular since this later
on allows to hold state in env->insn_aux_data[env->insn_idx].
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Pull TPM updates from James Morris:
- Support for partial reads of /dev/tpm0.
- Clean up for TPM 1.x code: move the commands to tpm1-cmd.c and make
everything to use the same data structure for building TPM commands
i.e. struct tpm_buf.
* 'next-tpm' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (25 commits)
tpm: add support for partial reads
tpm: tpm_ibmvtpm: fix kdoc warnings
tpm: fix kdoc for tpm2_flush_context_cmd()
tpm: tpm_try_transmit() refactor error flow.
tpm: use u32 instead of int for PCR index
tpm1: reimplement tpm1_continue_selftest() using tpm_buf
tpm1: reimplement SAVESTATE using tpm_buf
tpm1: rename tpm1_pcr_read_dev to tpm1_pcr_read()
tpm1: implement tpm1_pcr_read_dev() using tpm_buf structure
tpm: tpm1: rewrite tpm1_get_random() using tpm_buf structure
tpm: tpm-space.c remove unneeded semicolon
tpm: tpm-interface.c drop unused macros
tpm: add tpm_auto_startup() into tpm-interface.c
tpm: factor out tpm_startup function
tpm: factor out tpm 1.x pm suspend flow into tpm1-cmd.c
tpm: move tpm 1.x selftest code from tpm-interface.c tpm1-cmd.c
tpm: factor out tpm1_get_random into tpm1-cmd.c
tpm: move tpm_getcap to tpm1-cmd.c
tpm: move tpm1_pcr_extend to tpm1-cmd.c
tpm: factor out tpm_get_timeouts()
...
Pull seccomp updates from James Morris:
- Add SECCOMP_RET_USER_NOTIF
- seccomp fixes for sparse warnings and s390 build (Tycho)
* 'next-seccomp' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
seccomp, s390: fix build for syscall type change
seccomp: fix poor type promotion
samples: add an example of seccomp user trap
seccomp: add a return code to trap to userspace
seccomp: switch system call argument type to void *
seccomp: hoist struct seccomp_data recalculation higher
Pull integrity updates from James Morris:
"In Linux 4.19, a new LSM hook named security_kernel_load_data was
upstreamed, allowing LSMs and IMA to prevent the kexec_load syscall.
Different signature verification methods exist for verifying the
kexec'ed kernel image. This adds additional support in IMA to prevent
loading unsigned kernel images via the kexec_load syscall,
independently of the IMA policy rules, based on the runtime "secure
boot" flag. An initial IMA kselftest is included.
In addition, this pull request defines a new, separate keyring named
".platform" for storing the preboot/firmware keys needed for verifying
the kexec'ed kernel image's signature and includes the associated IMA
kexec usage of the ".platform" keyring.
(David Howell's and Josh Boyer's patches for reading the
preboot/firmware keys, which were previously posted for a different
use case scenario, are included here)"
* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
integrity: Remove references to module keyring
ima: Use inode_is_open_for_write
ima: Support platform keyring for kernel appraisal
efi: Allow the "db" UEFI variable to be suppressed
efi: Import certificates from UEFI Secure Boot
efi: Add an EFI signature blob parser
efi: Add EFI signature data types
integrity: Load certs to the platform keyring
integrity: Define a trusted platform keyring
selftests/ima: kexec_load syscall test
ima: don't measure/appraise files on efivarfs
x86/ima: retry detecting secure boot mode
docs: Extend trusted keys documentation for TPM 2.0
x86/ima: define arch_get_ima_policy() for x86
ima: add support for arch specific policies
ima: refactor ima_init_policy()
ima: prevent kexec_load syscall based on runtime secureboot flag
x86/ima: define arch_ima_get_secureboot
integrity: support new struct public_key_signature encoding field
Multipathing: In case of NFSv3, rpc_clnt_test_and_add_xprt() adds
the xprt to xprt switch (i.e. xps) if rpc_call_null_helper() returns
success. But in case of NFSv4.1, it needs to do EXCHANGEID to verify
the path along with check for session trunking.
Add the xprt in nfs4_test_session_trunk() only when
nfs4_detect_session_trunking() returns success. Also release refcount
hold by rpc_clnt_setup_test_and_add_xprt().
Signed-off-by: Santosh kumar pradhan <santoshkumar.pradhan@wdc.com>
Tested-by: Suresh Jayaraman <suresh.jayaraman@wdc.com>
Reported-by: Aditya Agnihotri <aditya.agnihotri@wdc.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
If a reply has been processed but the RPC is later retransmitted
anyway, the req->rl_reply field still contains the only pointer to
the old rpcrdma rep. When the next reply comes in, the reply handler
will stomp on the rl_reply field, leaking the old rep.
A trace event is added to capture such leaks.
This problem seems to be worsened by the restructuring of the RPC
Call path in v4.20. Fully addressing this issue will require at
least a re-architecture of the disconnect logic, which is not
appropriate during -rc.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Name them "trace_xprtrdma_op_*" so they can be easily enabled as a
group. No trace point is added where the generic layer already has
observability.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
