Daniel Borkmann says:
====================
pull-request: bpf 2017-11-23
The following pull-request contains BPF updates for your *net* tree.
The main changes are:
1) Several BPF offloading fixes, from Jakub. Among others:
- Limit offload to cls_bpf and XDP program types only.
- Move device validation into the driver and don't make
any assumptions about the device in the classifier due
to shared blocks semantics.
- Don't pass offloaded XDP program into the driver when
it should be run in native XDP instead. Offloaded ones
are not JITed for the host in such cases.
- Don't destroy device offload state when moved to
another namespace.
- Revert dumping offload info into user space for now,
since ifindex alone is not sufficient. This will be
redone properly for bpf-next tree.
2) Fix test_verifier to avoid using bpf_probe_write_user()
helper in test cases, since it's dumping a warning into
kernel log which may confuse users when only running tests.
Switch to use bpf_trace_printk() instead, from Yonghong.
3) Several fixes for correcting ARG_CONST_SIZE_OR_ZERO semantics
before it becomes uabi, from Gianluca. More specifically:
- Add a type ARG_PTR_TO_MEM_OR_NULL that is used only
by bpf_csum_diff(), where the argument is either a
valid pointer or NULL. The subsequent ARG_CONST_SIZE_OR_ZERO
then enforces a valid pointer in case of non-0 size
or a valid pointer or NULL in case of size 0. Given
that, the semantics for ARG_PTR_TO_MEM in combination
with ARG_CONST_SIZE_OR_ZERO are now such that in case
of size 0, the pointer must always be valid and cannot
be NULL. This fix in semantics allows for bpf_probe_read()
to drop the recently added size == 0 check in the helper
that would become part of uabi otherwise once released.
At the same time we can then fix bpf_probe_read_str() and
bpf_perf_event_output() to use ARG_CONST_SIZE_OR_ZERO
instead of ARG_CONST_SIZE in order to fix recently
reported issues by Arnaldo et al, where LLVM optimizes
two boundary checks into a single one for unknown
variables where the verifier looses track of the variable
bounds and thus rejects valid programs otherwise.
4) A fix for the verifier for the case when it detects
comparison of two constants where the branch is guaranteed
to not be taken at runtime. Verifier will rightfully prune
the exploration of such paths, but we still pass the program
to JITs, where they would complain about using reserved
fields, etc. Track such dead instructions and sanitize
them with mov r0,r0. Rejection is not possible since LLVM
may generate them for valid C code and doesn't do as much
data flow analysis as verifier. For bpf-next we might
implement removal of such dead code and adjust branches
instead. Fix from Alexei.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
when the verifier detects that register contains a runtime constant
and it's compared with another constant it will prune exploration
of the branch that is guaranteed not to be taken at runtime.
This is all correct, but malicious program may be constructed
in such a way that it always has a constant comparison and
the other branch is never taken under any conditions.
In this case such path through the program will not be explored
by the verifier. It won't be taken at run-time either, but since
all instructions are JITed the malicious program may cause JITs
to complain about using reserved fields, etc.
To fix the issue we have to track the instructions explored by
the verifier and sanitize instructions that are dead at run time
with NOPs. We cannot reject such dead code, since llvm generates
it for valid C code, since it doesn't do as much data flow
analysis as the verifier does.
Fixes: 17a5267067 ("bpf: verifier (add verifier core)")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Commit 9fd29c08e5 ("bpf: improve verifier ARG_CONST_SIZE_OR_ZERO
semantics") relaxed the treatment of ARG_CONST_SIZE_OR_ZERO due to the way
the compiler generates optimized BPF code when checking boundaries of an
argument from C code. A typical example of this optimized code can be
generated using the bpf_perf_event_output helper when operating on variable
memory:
/* len is a generic scalar */
if (len > 0 && len <= 0x7fff)
bpf_perf_event_output(ctx, &perf_map, 0, buf, len);
110: (79) r5 = *(u64 *)(r10 -40)
111: (bf) r1 = r5
112: (07) r1 += -1
113: (25) if r1 > 0x7ffe goto pc+6
114: (bf) r1 = r6
115: (18) r2 = 0xffff94e5f166c200
117: (b7) r3 = 0
118: (bf) r4 = r7
119: (85) call bpf_perf_event_output#25
R5 min value is negative, either use unsigned or 'var &= const'
With this code, the verifier loses track of the variable.
Replacing arg5 with ARG_CONST_SIZE_OR_ZERO is thus desirable since it
avoids this quite common case which leads to usability issues, and the
compiler generates code that the verifier can more easily test:
if (len <= 0x7fff)
bpf_perf_event_output(ctx, &perf_map, 0, buf, len);
or
bpf_perf_event_output(ctx, &perf_map, 0, buf, len & 0x7fff);
No changes to the bpf_perf_event_output helper are necessary since it can
handle a case where size is 0, and an empty frame is pushed.
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Gianluca Borello <g.borello@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Commit 9fd29c08e5 ("bpf: improve verifier ARG_CONST_SIZE_OR_ZERO
semantics") relaxed the treatment of ARG_CONST_SIZE_OR_ZERO due to the way
the compiler generates optimized BPF code when checking boundaries of an
argument from C code. A typical example of this optimized code can be
generated using the bpf_probe_read_str helper when operating on variable
memory:
/* len is a generic scalar */
if (len > 0 && len <= 0x7fff)
bpf_probe_read_str(p, len, s);
251: (79) r1 = *(u64 *)(r10 -88)
252: (07) r1 += -1
253: (25) if r1 > 0x7ffe goto pc-42
254: (bf) r1 = r7
255: (79) r2 = *(u64 *)(r10 -88)
256: (bf) r8 = r4
257: (85) call bpf_probe_read_str#45
R2 min value is negative, either use unsigned or 'var &= const'
With this code, the verifier loses track of the variable.
Replacing arg2 with ARG_CONST_SIZE_OR_ZERO is thus desirable since it
avoids this quite common case which leads to usability issues, and the
compiler generates code that the verifier can more easily test:
if (len <= 0x7fff)
bpf_probe_read_str(p, len, s);
or
bpf_probe_read_str(p, len & 0x7fff, s);
No changes to the bpf_probe_read_str helper are necessary since
strncpy_from_unsafe itself immediately returns if the size passed is 0.
Signed-off-by: Gianluca Borello <g.borello@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Commit 9c019e2bc4 ("bpf: change helper bpf_probe_read arg2 type to
ARG_CONST_SIZE_OR_ZERO") changed arg2 type to ARG_CONST_SIZE_OR_ZERO to
simplify writing bpf programs by taking advantage of the new semantics
introduced for ARG_CONST_SIZE_OR_ZERO which allows <!NULL, 0> arguments.
In order to prevent the helper from actually passing a NULL pointer to
probe_kernel_read, which can happen when <NULL, 0> is passed to the helper,
the commit also introduced an explicit check against size == 0.
After the recent introduction of the ARG_PTR_TO_MEM_OR_NULL type,
bpf_probe_read can not receive a pair of <NULL, 0> arguments anymore, thus
the check is not needed anymore and can be removed, since probe_kernel_read
can correctly handle a <!NULL, 0> call. This also fixes the semantics of
the helper before it gets officially released and bpf programs start
relying on this check.
Fixes: 9c019e2bc4 ("bpf: change helper bpf_probe_read arg2 type to ARG_CONST_SIZE_OR_ZERO")
Signed-off-by: Gianluca Borello <g.borello@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
With the current ARG_PTR_TO_MEM/ARG_PTR_TO_UNINIT_MEM semantics, an helper
argument can be NULL when the next argument type is ARG_CONST_SIZE_OR_ZERO
and the verifier can prove the value of this next argument is 0. However,
most helpers are just interested in handling <!NULL, 0>, so forcing them to
deal with <NULL, 0> makes the implementation of those helpers more
complicated for no apparent benefits, requiring them to explicitly handle
those corner cases with checks that bpf programs could start relying upon,
preventing the possibility of removing them later.
Solve this by making ARG_PTR_TO_MEM/ARG_PTR_TO_UNINIT_MEM never accept NULL
even when ARG_CONST_SIZE_OR_ZERO is set, and introduce a new argument type
ARG_PTR_TO_MEM_OR_NULL to explicitly deal with the NULL case.
Currently, the only helper that needs this is bpf_csum_diff_proto(), so
change arg1 and arg3 to this new type as well.
Also add a new battery of tests that explicitly test the
!ARG_PTR_TO_MEM_OR_NULL combination: all the current ones testing the
various <NULL, 0> variations are focused on bpf_csum_diff, so cover also
other helpers.
Signed-off-by: Gianluca Borello <g.borello@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Pull printk updates from Petr Mladek:
- print the warning about dropped messages on consoles on a separate
line. It makes it more legible.
- one typo fix and small code clean up.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
added new line symbol after warning about dropped messages
printk: fix typo in printk_safe.c
printk: simplify no_printk()
This reverts commit bd601b6ada ("bpf: report offload info to user
space"). The ifindex by itself is not sufficient, we should provide
information on which network namespace this ifindex belongs to.
After considering some options we concluded that it's best to just
remove this API for now, and rework it in -next.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
We are currently destroying the device offload state when device
moves to another net namespace. This doesn't break with current
NFP code, because offload state is not used on program removal,
but it's not correct behaviour.
Ignore the device unregister notifications on namespace move.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
bpf_prog_get_type() is identical to bpf_prog_get_type_dev(),
with false passed as attach_drv. Instead of keeping it as
an exported symbol turn it into static inline wrapper.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
With TC shared block changes we can't depend on correct netdev
pointer being available in cls_bpf. Move the device validation
to the driver. Core will only make sure that offloaded programs
are always attached in the driver (or in HW by the driver). We
trust that drivers which implement offload callbacks will perform
necessary checks.
Moving the checks to the driver is generally a useful thing,
in practice the check should be against a switchdev instance,
not a netdev, given that most ASICs will probably allow using
the same program on many ports.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
bpf_target_prog seems long and clunky, rename it to prog_ifindex.
We don't want to call this field just ifindex, because maps
may need a similar field in the future and bpf_attr members for
programs and maps are unnamed.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
We are currently only allowing attachment of device-bound
cls_bpf and XDP programs. Make this restriction explicit in
the BPF offload code. This way we can potentially reuse the
ifindex field in the future.
Since XDP and cls_bpf programs can only be loaded by admin,
we can drop the explicit capability check from offload code.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Offload state may get destroyed either because the device for which
it was constructed is going away, or because the refcount of bpf
program itself has reached 0. In both of those cases we will call
__bpf_prog_offload_destroy() to unlink the offload from the device.
We may in fact call it twice, which works just fine, but we should
make clear this is intended and caution others trying to extend the
function.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This is the gist of a patch which we've been forward-porting in our
kernels for a long time now and it probably would make a good sense to
have such TAINT_AUX flag upstream which can be used by each distro etc,
how they see fit. This way, we won't need to forward-port a distro-only
version indefinitely.
Add an auxiliary taint flag to be used by distros and others. This
obviates the need to forward-port whatever internal solutions people
have in favor of a single flag which they can map arbitrarily to a
definition of their pleasing.
The "X" mnemonic could also mean eXternal, which would be taint from a
distro or something else but not the upstream kernel. We will use it to
mark modules for which we don't provide support. I.e., a really
eXternal module.
Link: http://lkml.kernel.org/r/20170911134533.dp5mtyku5bongx4c@pd.tnic
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Replacing PID bitmap implementation with IDR API", v4.
This series replaces kernel bitmap implementation of PID allocation with
IDR API. These patches are written to simplify the kernel by replacing
custom code with calls to generic code.
The following are the stats for pid and pid_namespace object files
before and after the replacement. There is a noteworthy change between
the IDR and bitmap implementation.
Before
text data bss dec hex filename
8447 3894 64 12405 3075 kernel/pid.o
After
text data bss dec hex filename
3397 304 0 3701 e75 kernel/pid.o
Before
text data bss dec hex filename
5692 1842 192 7726 1e2e kernel/pid_namespace.o
After
text data bss dec hex filename
2854 216 16 3086 c0e kernel/pid_namespace.o
The following are the stats for ps, pstree and calling readdir on /proc
for 10,000 processes.
ps:
With IDR API With bitmap
real 0m1.479s 0m2.319s
user 0m0.070s 0m0.060s
sys 0m0.289s 0m0.516s
pstree:
With IDR API With bitmap
real 0m1.024s 0m1.794s
user 0m0.348s 0m0.612s
sys 0m0.184s 0m0.264s
proc:
With IDR API With bitmap
real 0m0.059s 0m0.074s
user 0m0.000s 0m0.004s
sys 0m0.016s 0m0.016s
This patch (of 2):
Replace the current bitmap implementation for Process ID allocation.
Functions that are no longer required, for example, free_pidmap(),
alloc_pidmap(), etc. are removed. The rest of the functions are
modified to use the IDR API. The change was made to make the PID
allocation less complex by replacing custom code with calls to generic
API.
[gs051095@gmail.com: v6]
Link: http://lkml.kernel.org/r/1507760379-21662-2-git-send-email-gs051095@gmail.com
[avagin@openvz.org: restore the old behaviour of the ns_last_pid sysctl]
Link: http://lkml.kernel.org/r/20171106183144.16368-1-avagin@openvz.org
Link: http://lkml.kernel.org/r/1507583624-22146-2-git-send-email-gs051095@gmail.com
Signed-off-by: Gargi Sharma <gs051095@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
complete_signal() checks SIGNAL_UNKILLABLE before it starts to destroy
the thread group, today this is wrong in many ways.
If nothing else, fatal_signal_pending() should always imply that the
whole thread group (except ->group_exit_task if it is not NULL) is
killed, this check breaks the rule.
After the previous changes we can rely on sig_task_ignored();
sig_fatal(sig) && SIGNAL_UNKILLABLE can only be true if we actually want
to kill this task and sig == SIGKILL OR it is traced and debugger can
intercept the signal.
This should hopefully fix the problem reported by Dmitry. This
test-case
static int init(void *arg)
{
for (;;)
pause();
}
int main(void)
{
char stack[16 * 1024];
for (;;) {
int pid = clone(init, stack + sizeof(stack)/2,
CLONE_NEWPID | SIGCHLD, NULL);
assert(pid > 0);
assert(ptrace(PTRACE_ATTACH, pid, 0, 0) == 0);
assert(waitpid(-1, NULL, WSTOPPED) == pid);
assert(ptrace(PTRACE_DETACH, pid, 0, SIGSTOP) == 0);
assert(syscall(__NR_tkill, pid, SIGKILL) == 0);
assert(pid == wait(NULL));
}
}
triggers the WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING)) in
task_participate_group_stop(). do_signal_stop()->signal_group_exit()
checks SIGNAL_GROUP_EXIT and return false, but task_set_jobctl_pending()
checks fatal_signal_pending() and does not set JOBCTL_STOP_PENDING.
And his should fix the minor security problem reported by Kyle,
SECCOMP_RET_TRACE can miss fatal_signal_pending() the same way if the
task is the root of a pid namespace.
Link: http://lkml.kernel.org/r/20171103184246.GD21036@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reported-by: Kyle Huey <me@kylehuey.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kyle Huey <me@kylehuey.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
