syzkaller tried to perform a prog query in perf_event_query_prog_array()
where struct perf_event_query_bpf had an ids_len of 1,073,741,353 and
thus causing a warning due to failed kcalloc() allocation out of the
bpf_prog_array_copy_to_user() helper. Given we cannot attach more than
64 programs to a perf event, there's no point in allowing huge ids_len.
Therefore, allow a buffer that would fix the maximum number of ids and
also add a __GFP_NOWARN to the temporary ids buffer.
Fixes: f371b304f1 ("bpf/tracing: allow user space to query prog array on the same tp")
Fixes: 0911287ce3 ("bpf: fix bpf_prog_array_copy_to_user() issues")
Reported-by: syzbot+cab5816b0edbabf598b3@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, for bpf_trace_printk helper, fake ip address 0x1
is used with comments saying that fake ip will not be printed.
This is indeed true for 4.12 and earlier version, but for
4.13 and later version, the ip address will be printed if
it cannot be resolved with kallsym. Running samples/bpf/tracex5
program and you will have the following in the debugfs
trace_pipe output:
...
<...>-1819 [003] .... 443.497877: 0x00000001: mmap
<...>-1819 [003] .... 443.498289: 0x00000001: syscall=102 (one of get/set uid/pid/gid)
...
The kernel commit changed this behavior is:
commit feaf1283d1
Author: Steven Rostedt (VMware) <rostedt@goodmis.org>
Date: Thu Jun 22 17:04:55 2017 -0400
tracing: Show address when function names are not found
...
This patch changed the comment and also altered the fake ip
address to 0x0 as users may think 0x1 has some special meaning
while it doesn't. The new output:
...
<...>-1799 [002] .... 25.953576: 0: mmap
<...>-1799 [002] .... 25.953865: 0: read(fd=0, buf=00000000053936b5, size=512)
...
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Since error-injection framework is not limited to be used
by kprobes, nor bpf. Other kernel subsystems can use it
freely for checking safeness of error-injection, e.g.
livepatch, ftrace etc.
So this separate error-injection framework from kprobes.
Some differences has been made:
- "kprobe" word is removed from any APIs/structures.
- BPF_ALLOW_ERROR_INJECTION() is renamed to
ALLOW_ERROR_INJECTION() since it is not limited for BPF too.
- CONFIG_FUNCTION_ERROR_INJECTION is the config item of this
feature. It is automatically enabled if the arch supports
error injection feature for kprobe or ftrace etc.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Compare instruction pointer with original one on the
stack instead using per-cpu bpf_kprobe_override flag.
This patch also consolidates reset_current_kprobe() and
preempt_enable_no_resched() blocks. Those can be done
in one place.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Check whether error injectable event is on function entry or not.
Currently it checks the event is ftrace-based kprobes or not,
but that is wrong. It should check if the event is on the entry
of target function. Since error injection will override a function
to just return with modified return value, that operation must
be done before the target function starts making stackframe.
As a side effect, bpf error injection is no need to depend on
function-tracer. It can work with sw-breakpoint based kprobe
events too.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Daniel Borkmann says:
====================
pull-request: bpf-next 2017-12-18
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Allow arbitrary function calls from one BPF function to another BPF function.
As of today when writing BPF programs, __always_inline had to be used in
the BPF C programs for all functions, unnecessarily causing LLVM to inflate
code size. Handle this more naturally with support for BPF to BPF calls
such that this __always_inline restriction can be overcome. As a result,
it allows for better optimized code and finally enables to introduce core
BPF libraries in the future that can be reused out of different projects.
x86 and arm64 JIT support was added as well, from Alexei.
2) Add infrastructure for tagging functions as error injectable and allow for
BPF to return arbitrary error values when BPF is attached via kprobes on
those. This way of injecting errors generically eases testing and debugging
without having to recompile or restart the kernel. Tags for opting-in for
this facility are added with BPF_ALLOW_ERROR_INJECTION(), from Josef.
3) For BPF offload via nfp JIT, add support for bpf_xdp_adjust_head() helper
call for XDP programs. First part of this work adds handling of BPF
capabilities included in the firmware, and the later patches add support
to the nfp verifier part and JIT as well as some small optimizations,
from Jakub.
4) The bpftool now also gets support for basic cgroup BPF operations such
as attaching, detaching and listing current BPF programs. As a requirement
for the attach part, bpftool can now also load object files through
'bpftool prog load'. This reuses libbpf which we have in the kernel tree
as well. bpftool-cgroup man page is added along with it, from Roman.
5) Back then commit e87c6bc385 ("bpf: permit multiple bpf attachments for
a single perf event") added support for attaching multiple BPF programs
to a single perf event. Given they are configured through perf's ioctl()
interface, the interface has been extended with a PERF_EVENT_IOC_QUERY_BPF
command in this work in order to return an array of one or multiple BPF
prog ids that are currently attached, from Yonghong.
6) Various minor fixes and cleanups to the bpftool's Makefile as well
as a new 'uninstall' and 'doc-uninstall' target for removing bpftool
itself or prior installed documentation related to it, from Quentin.
7) Add CONFIG_CGROUP_BPF=y to the BPF kernel selftest config file which is
required for the test_dev_cgroup test case to run, from Naresh.
8) Fix reporting of XDP prog_flags for nfp driver, from Jakub.
9) Fix libbpf's exit code from the Makefile when libelf was not found in
the system, also from Jakub.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit f371b304f1 ("bpf/tracing: allow user space to
query prog array on the same tp") introduced a perf
ioctl command to query prog array attached to the
same perf tracepoint. The commit introduced a
compilation error under certain config conditions, e.g.,
(1). CONFIG_BPF_SYSCALL is not defined, or
(2). CONFIG_TRACING is defined but neither CONFIG_UPROBE_EVENTS
nor CONFIG_KPROBE_EVENTS is defined.
Error message:
kernel/events/core.o: In function `perf_ioctl':
core.c:(.text+0x98c4): undefined reference to `bpf_event_query_prog_array'
This patch fixed this error by guarding the real definition under
CONFIG_BPF_EVENTS and provided static inline dummy function
if CONFIG_BPF_EVENTS was not defined.
It renamed the function from bpf_event_query_prog_array to
perf_event_query_prog_array and moved the definition from linux/bpf.h
to linux/trace_events.h so the definition is in proximity to
other prog_array related functions.
Fixes: f371b304f1 ("bpf/tracing: allow user space to query prog array on the same tp")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
When tracing and networking programs are both attached in the
system and both use event-output helpers that eventually call
into perf_event_output(), then we could end up in a situation
where the tracing attached program runs in user context while
a cls_bpf program is triggered on that same CPU out of softirq
context.
Since both rely on the same per-cpu perf_sample_data, we could
potentially corrupt it. This can only ever happen in a combination
of the two types; all tracing programs use a bpf_prog_active
counter to bail out in case a program is already running on
that CPU out of a different context. XDP and cls_bpf programs
by themselves don't have this issue as they run in the same
context only. Therefore, split both perf_sample_data so they
cannot be accessed from each other.
Fixes: 20b9d7ac48 ("bpf: avoid excessive stack usage for perf_sample_data")
Reported-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Song Liu <songliubraving@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Error injection is sloppy and very ad-hoc. BPF could fill this niche
perfectly with it's kprobe functionality. We could make sure errors are
only triggered in specific call chains that we care about with very
specific situations. Accomplish this with the bpf_override_funciton
helper. This will modify the probe'd callers return value to the
specified value and set the PC to an override function that simply
returns, bypassing the originally probed function. This gives us a nice
clean way to implement systematic error injection for all of our code
paths.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Commit e87c6bc385 ("bpf: permit multiple bpf attachments
for a single perf event") added support to attach multiple
bpf programs to a single perf event.
Although this provides flexibility, users may want to know
what other bpf programs attached to the same tp interface.
Besides getting visibility for the underlying bpf system,
such information may also help consolidate multiple bpf programs,
understand potential performance issues due to a large array,
and debug (e.g., one bpf program which overwrites return code
may impact subsequent program results).
Commit 2541517c32 ("tracing, perf: Implement BPF programs
attached to kprobes") utilized the existing perf ioctl
interface and added the command PERF_EVENT_IOC_SET_BPF
to attach a bpf program to a tracepoint. This patch adds a new
ioctl command, given a perf event fd, to query the bpf program
array attached to the same perf tracepoint event.
The new uapi ioctl command:
PERF_EVENT_IOC_QUERY_BPF
The new uapi/linux/perf_event.h structure:
struct perf_event_query_bpf {
__u32 ids_len;
__u32 prog_cnt;
__u32 ids[0];
};
User space provides buffer "ids" for kernel to copy to.
When returning from the kernel, the number of available
programs in the array is set in "prog_cnt".
The usage:
struct perf_event_query_bpf *query =
malloc(sizeof(*query) + sizeof(u32) * ids_len);
query.ids_len = ids_len;
err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, query);
if (err == 0) {
/* query.prog_cnt is the number of available progs,
* number of progs in ids: (ids_len == 0) ? 0 : query.prog_cnt
*/
} else if (errno == ENOSPC) {
/* query.ids_len number of progs copied,
* query.prog_cnt is the number of available progs
*/
} else {
/* other errors */
}
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
cgropu+bpf prog array has a maximum number of 64 programs.
Let us apply the same limit here.
Fixes: e87c6bc385 ("bpf: permit multiple bpf attachments for a single perf event")
Signed-off-by: Yonghong Song <yhs@fb.com>
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>
The helper bpf_probe_read arg2 type is changed
from ARG_CONST_SIZE to ARG_CONST_SIZE_OR_ZERO to permit
size-0 buffer. Together with newer ARG_CONST_SIZE_OR_ZERO
semantics which allows non-NULL buffer with size 0,
this allows simpler bpf programs with verifier acceptance.
The previous commit which changes ARG_CONST_SIZE_OR_ZERO semantics
has details on examples.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Error injection is sloppy and very ad-hoc. BPF could fill this niche
perfectly with it's kprobe functionality. We could make sure errors are
only triggered in specific call chains that we care about with very
specific situations. Accomplish this with the bpf_override_funciton
helper. This will modify the probe'd callers return value to the
specified value and set the PC to an override function that simply
returns, bypassing the originally probed function. This gives us a nice
clean way to implement systematic error injection for all of our code
paths.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
During perf event attaching/detaching bpf programs,
the tp_event->prog_array change is protected by the
bpf_event_mutex lock in both attaching and deteching
functions. Although tp_event->prog_array is a rcu
pointer, rcu_derefrence is not needed to access it
since mutex lock will guarantee ordering.
Verified through "make C=2" that sparse
locking check still happy with the new change.
Also change the label name in perf_event_{attach,detach}_bpf_prog
from "out" to "unlock" to reflect the code action after the label.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
commit afdb09c720 ("security: bpf: Add LSM hooks for bpf object related
syscall") included linux/bpf.h in linux/security.h. As a result, bpf
programs including bpf_helpers.h and some other header that ends up
pulling in also security.h, such as several examples under samples/bpf,
fail to compile because bpf_tail_call and bpf_get_stackid are now
"redefined as different kind of symbol".
>From bpf.h:
u64 bpf_tail_call(u64 ctx, u64 r2, u64 index, u64 r4, u64 r5);
u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
Whereas in bpf_helpers.h they are:
static void (*bpf_tail_call)(void *ctx, void *map, int index);
static int (*bpf_get_stackid)(void *ctx, void *map, int flags);
Fix this by removing the unused declaration of bpf_tail_call and moving
the declaration of bpf_get_stackid in bpf_trace.c, which is the only
place where it's needed.
Signed-off-by: Gianluca Borello <g.borello@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch enables multiple bpf attachments for a
kprobe/uprobe/tracepoint single trace event.
Each trace_event keeps a list of attached perf events.
When an event happens, all attached bpf programs will
be executed based on the order of attachment.
A global bpf_event_mutex lock is introduced to protect
prog_array attaching and detaching. An alternative will
be introduce a mutex lock in every trace_event_call
structure, but it takes a lot of extra memory.
So a global bpf_event_mutex lock is a good compromise.
The bpf prog detachment involves allocation of memory.
If the allocation fails, a dummy do-nothing program
will replace to-be-detached program in-place.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
struct bpf_verifier_ops contains both verifier ops and operations
used later during program's lifetime (test_run). Split the runtime
ops into a different structure.
BPF_PROG_TYPE() will now append ## _prog_ops or ## _verifier_ops
to the names.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds helper bpf_perf_prog_read_cvalue for perf event based bpf
programs, to read event counter and enabled/running time.
The enabled/running time is accumulated since the perf event open.
The typical use case for perf event based bpf program is to attach itself
to a single event. In such cases, if it is desirable to get scaling factor
between two bpf invocations, users can can save the time values in a map,
and use the value from the map and the current value to calculate
the scaling factor.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Hardware pmu counters are limited resources. When there are more
pmu based perf events opened than available counters, kernel will
multiplex these events so each event gets certain percentage
(but not 100%) of the pmu time. In case that multiplexing happens,
the number of samples or counter value will not reflect the
case compared to no multiplexing. This makes comparison between
different runs difficult.
Typically, the number of samples or counter value should be
normalized before comparing to other experiments. The typical
normalization is done like:
normalized_num_samples = num_samples * time_enabled / time_running
normalized_counter_value = counter_value * time_enabled / time_running
where time_enabled is the time enabled for event and time_running is
the time running for event since last normalization.
This patch adds helper bpf_perf_event_read_value for kprobed based perf
event array map, to read perf counter and enabled/running time.
The enabled/running time is accumulated since the perf event open.
To achieve scaling factor between two bpf invocations, users
can can use cpu_id as the key (which is typical for perf array usage model)
to remember the previous value and do the calculation inside the
bpf program.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch does not impact existing functionalities.
It contains the changes in perf event area needed for
subsequent bpf_perf_event_read_value and
bpf_perf_prog_read_value helpers.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
James reported that on MIPS32 bpf_trace_printk() is currently
broken while MIPS64 works fine:
bpf_trace_printk() uses conditional operators to attempt to
pass different types to __trace_printk() depending on the
format operators. This doesn't work as intended on 32-bit
architectures where u32 and long are passed differently to
u64, since the result of C conditional operators follows the
"usual arithmetic conversions" rules, such that the values
passed to __trace_printk() will always be u64 [causing issues
later in the va_list handling for vscnprintf()].
For example the samples/bpf/tracex5 test printed lines like
below on MIPS32, where the fd and buf have come from the u64
fd argument, and the size from the buf argument:
[...] 1180.941542: 0x00000001: write(fd=1, buf= (null), size=6258688)
Instead of this:
[...] 1625.616026: 0x00000001: write(fd=1, buf=009e4000, size=512)
One way to get it working is to expand various combinations
of argument types into 8 different combinations for 32 bit
and 64 bit kernels. Fix tested by James on MIPS32 and MIPS64
as well that it resolves the issue.
Fixes: 9c959c863f ("tracing: Allow BPF programs to call bpf_trace_printk()")
Reported-by: James Hogan <james.hogan@imgtec.com>
Tested-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, bpf_trace_printk does not support common formatting
symbol '%i' however vsprintf does and is what eventually gets
called by bpf helper. If users are used to '%i' and currently
make use of it, then bpf_trace_printk will just return with
error without dumping anything to the trace pipe, so just add
support for '%i' to the helper.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This work tries to make the semantics and code around the
narrower ctx access a bit easier to follow. Right now
everything is done inside the .is_valid_access(). Offset
matching is done differently for read/write types, meaning
writes don't support narrower access and thus matching only
on offsetof(struct foo, bar) is enough whereas for read
case that supports narrower access we must check for
offsetof(struct foo, bar) + offsetof(struct foo, bar) +
sizeof(<bar>) - 1 for each of the cases. For read cases of
individual members that don't support narrower access (like
packet pointers or skb->cb[] case which has its own narrow
access logic), we check as usual only offsetof(struct foo,
bar) like in write case. Then, for the case where narrower
access is allowed, we also need to set the aux info for the
access. Meaning, ctx_field_size and converted_op_size have
to be set. First is the original field size e.g. sizeof(<bar>)
as in above example from the user facing ctx, and latter
one is the target size after actual rewrite happened, thus
for the kernel facing ctx. Also here we need the range match
and we need to keep track changing convert_ctx_access() and
converted_op_size from is_valid_access() as both are not at
the same location.
We can simplify the code a bit: check_ctx_access() becomes
simpler in that we only store ctx_field_size as a meta data
and later in convert_ctx_accesses() we fetch the target_size
right from the location where we do convert. Should the verifier
be misconfigured we do reject for BPF_WRITE cases or target_size
that are not provided. For the subsystems, we always work on
ranges in is_valid_access() and add small helpers for ranges
and narrow access, convert_ctx_accesses() sets target_size
for the relevant instruction.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Cc: Yonghong Song <yhs@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 31fd85816d ("bpf: permits narrower load from bpf program
context fields") permits narrower load for certain ctx fields.
The commit however will already generate a masking even if
the prog-specific ctx conversion produces the result with
narrower size.
For example, for __sk_buff->protocol, the ctx conversion
loads the data into register with 2-byte load.
A narrower 2-byte load should not generate masking.
For __sk_buff->vlan_present, the conversion function
set the result as either 0 or 1, essentially a byte.
The narrower 2-byte or 1-byte load should not generate masking.
To avoid unnecessary masking, prog-specific *_is_valid_access
now passes converted_op_size back to verifier, which indicates
the valid data width after perceived future conversion.
Based on this information, verifier is able to avoid
unnecessary marking.
Since we want more information back from prog-specific
*_is_valid_access checking, all of them are packed into
one data structure for more clarity.
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, verifier will reject a program if it contains an
narrower load from the bpf context structure. For example,
__u8 h = __sk_buff->hash, or
__u16 p = __sk_buff->protocol
__u32 sample_period = bpf_perf_event_data->sample_period
which are narrower loads of 4-byte or 8-byte field.
This patch solves the issue by:
. Introduce a new parameter ctx_field_size to carry the
field size of narrower load from prog type
specific *__is_valid_access validator back to verifier.
. The non-zero ctx_field_size for a memory access indicates
(1). underlying prog type specific convert_ctx_accesses
supporting non-whole-field access
(2). the current insn is a narrower or whole field access.
. In verifier, for such loads where load memory size is
less than ctx_field_size, verifier transforms it
to a full field load followed by proper masking.
. Currently, __sk_buff and bpf_perf_event_data->sample_period
are supporting narrowing loads.
. Narrower stores are still not allowed as typical ctx stores
are just normal stores.
Because of this change, some tests in verifier will fail and
these tests are removed. As a bonus, rename some out of bound
__sk_buff->cb access to proper field name and remove two
redundant "skb cb oob" tests.
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
perf_sample_data consumes 386 bytes on stack, reduce excessive stack
usage and move it to per cpu buffer. It's allowed due to preemption
being disabled for tracing, xdp and tc programs, thus at all times
only one program can run on a specific CPU and programs cannot run
from interrupt. We similarly also handle bpf_pt_regs.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Allow BPF_PROG_TYPE_PERF_EVENT program types to attach to all
perf_event types, including HW_CACHE, RAW, and dynamic pmu events.
Only tracepoint/kprobe events are treated differently which require
BPF_PROG_TYPE_TRACEPOINT/BPF_PROG_TYPE_KPROBE program types accordingly.
Also add support for reading all event counters using
bpf_perf_event_read() helper.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull networking updates from David Millar:
"Here are some highlights from the 2065 networking commits that
happened this development cycle:
1) XDP support for IXGBE (John Fastabend) and thunderx (Sunil Kowuri)
2) Add a generic XDP driver, so that anyone can test XDP even if they
lack a networking device whose driver has explicit XDP support
(me).
3) Sparc64 now has an eBPF JIT too (me)
4) Add a BPF program testing framework via BPF_PROG_TEST_RUN (Alexei
Starovoitov)
5) Make netfitler network namespace teardown less expensive (Florian
Westphal)
6) Add symmetric hashing support to nft_hash (Laura Garcia Liebana)
7) Implement NAPI and GRO in netvsc driver (Stephen Hemminger)
8) Support TC flower offload statistics in mlxsw (Arkadi Sharshevsky)
9) Multiqueue support in stmmac driver (Joao Pinto)
10) Remove TCP timewait recycling, it never really could possibly work
well in the real world and timestamp randomization really zaps any
hint of usability this feature had (Soheil Hassas Yeganeh)
11) Support level3 vs level4 ECMP route hashing in ipv4 (Nikolay
Aleksandrov)
12) Add socket busy poll support to epoll (Sridhar Samudrala)
13) Netlink extended ACK support (Johannes Berg, Pablo Neira Ayuso,
and several others)
14) IPSEC hw offload infrastructure (Steffen Klassert)"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (2065 commits)
tipc: refactor function tipc_sk_recv_stream()
tipc: refactor function tipc_sk_recvmsg()
net: thunderx: Optimize page recycling for XDP
net: thunderx: Support for XDP header adjustment
net: thunderx: Add support for XDP_TX
net: thunderx: Add support for XDP_DROP
net: thunderx: Add basic XDP support
net: thunderx: Cleanup receive buffer allocation
net: thunderx: Optimize CQE_TX handling
net: thunderx: Optimize RBDR descriptor handling
net: thunderx: Support for page recycling
ipx: call ipxitf_put() in ioctl error path
net: sched: add helpers to handle extended actions
qed*: Fix issues in the ptp filter config implementation.
qede: Fix concurrency issue in PTP Tx path processing.
stmmac: Add support for SIMATIC IOT2000 platform
net: hns: fix ethtool_get_strings overflow in hns driver
tcp: fix wraparound issue in tcp_lp
bpf, arm64: fix jit branch offset related to ldimm64
bpf, arm64: implement jiting of BPF_XADD
...
There's no need to have struct bpf_prog_type_list since
it just contains a list_head, the type, and the ops
pointer. Since the types are densely packed and not
actually dynamically registered, it's much easier and
smaller to have an array of type->ops pointer. Also
initialize this array statically to remove code needed
to initialize it.
In order to save duplicating the list, move it to a new
header file and include it in the places needing it.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
All map types and prog types are registered to the BPF core through
bpf_register_map_type() and bpf_register_prog_type() during init and
remain unchanged thereafter. As by design we don't (and never will)
have any pluggable code that can register to that at any later point
in time, lets mark all the existing bpf_{map,prog}_type_list objects
in the tree as __ro_after_init, so they can be moved to read-only
section from then onwards.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Provide a simple helper with the same semantics of strncpy_from_unsafe():
int bpf_probe_read_str(void *dst, int size, const void *unsafe_addr)
This gives more flexibility to a bpf program. A typical use case is
intercepting a file name during sys_open(). The current approach is:
SEC("kprobe/sys_open")
void bpf_sys_open(struct pt_regs *ctx)
{
char buf[PATHLEN]; // PATHLEN is defined to 256
bpf_probe_read(buf, sizeof(buf), ctx->di);
/* consume buf */
}
This is suboptimal because the size of the string needs to be estimated
at compile time, causing more memory to be copied than often necessary,
and can become more problematic if further processing on buf is done,
for example by pushing it to userspace via bpf_perf_event_output(),
since the real length of the string is unknown and the entire buffer
must be copied (and defining an unrolled strnlen() inside the bpf
program is a very inefficient and unfeasible approach).
With the new helper, the code can easily operate on the actual string
length rather than the buffer size:
SEC("kprobe/sys_open")
void bpf_sys_open(struct pt_regs *ctx)
{
char buf[PATHLEN]; // PATHLEN is defined to 256
int res = bpf_probe_read_str(buf, sizeof(buf), ctx->di);
/* consume buf, for example push it to userspace via
* bpf_perf_event_output(), but this time we can use
* res (the string length) as event size, after checking
* its boundaries.
*/
}
Another useful use case is when parsing individual process arguments or
individual environment variables navigating current->mm->arg_start and
current->mm->env_start: using this helper and the return value, one can
quickly iterate at the right offset of the memory area.
The code changes simply leverage the already existent
strncpy_from_unsafe() kernel function, which is safe to be called from a
bpf program as it is used in bpf_trace_printk().
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: David S. Miller <davem@davemloft.net>
Make sure that ctx cannot potentially be accessed oob by asserting
explicitly that ctx access size into pt_regs for BPF_PROG_TYPE_KPROBE
programs must be within limits. In case some 32bit archs have pt_regs
not being a multiple of 8, then BPF_DW access could cause such access.
BPF_PROG_TYPE_KPROBE progs don't have a ctx conversion function since
there's no extra mapping needed. kprobe_prog_is_valid_access() didn't
enforce sizeof(long) as the only allowed access size, since LLVM can
generate non BPF_W/BPF_DW access to regs from time to time.
For BPF_PROG_TYPE_TRACEPOINT we don't have a ctx conversion either, so
add a BUILD_BUG_ON() check to make sure that BPF_DW access will not be
a similar issue in future (ctx works on event buffer as opposed to
pt_regs there).
Fixes: 2541517c32 ("tracing, perf: Implement BPF programs attached to kprobes")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, when calling convert_ctx_access() callback for the various
program types, we pass in insn->dst_reg, insn->src_reg, insn->off from
the original instruction. This information is needed to rewrite the
instruction that is based on the user ctx structure into a kernel
representation for the ctx. As we'd like to allow access size beyond
just BPF_W, we'd need also insn->code for that in order to decode the
original access size. Given that, lets just pass insn directly to the
convert_ctx_access() callback and work on that to not clutter the
callback with even more arguments we need to pass when everything is
already contained in insn. So lets go through that once, no functional
change.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
since ARG_PTR_TO_STACK is no longer just pointer to stack
rename it to ARG_PTR_TO_MEM and adjust comment.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use case is mainly for soreuseport to select sockets for the local
numa node, but since generic, lets also add this for other networking
and tracing program types.
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions
to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros
that are used today. Motivation for this is to hide all the register handling
and all necessary casts from the user, so that it is done automatically in the
background when adding a BPF_CALL_<n>() call.
This makes current helpers easier to review, eases to write future helpers,
avoids getting the casting mess wrong, and allows for extending all helpers at
once (f.e. build time checks, etc). It also helps detecting more easily in
code reviews that unused registers are not instrumented in the code by accident,
breaking compatibility with existing programs.
BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some
fundamental differences, for example, for generating the actual helper function
that carries all u64 regs, we need to fill unused regs, so that we always end up
with 5 u64 regs as an argument.
I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and
they look all as expected. No sparse issue spotted. We let this also sit for a
few days with Fengguang's kbuild test robot, and there were no issues seen. On
s390, it barked on the "uses dynamic stack allocation" notice, which is an old
one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion
to the call wrapper, just telling that the perf raw record/frag sits on stack
(gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests
and they were fine as well. All eBPF helpers are now converted to use these
macros, getting rid of a good chunk of all the raw castings.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add BPF_SIZEOF() and BPF_FIELD_SIZEOF() macros to improve the code a bit
which otherwise often result in overly long bytes_to_bpf_size(sizeof())
and bytes_to_bpf_size(FIELD_SIZEOF()) lines. So place them into a macro
helper instead. Moreover, we currently have a BUILD_BUG_ON(BPF_FIELD_SIZEOF())
check in convert_bpf_extensions(), but we should rather make that generic
as well and add a BUILD_BUG_ON() test in all BPF_SIZEOF()/BPF_FIELD_SIZEOF()
users to detect any rewriter size issues at compile time. Note, there are
currently none, but we want to assert that it stays this way.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Introduce BPF_PROG_TYPE_PERF_EVENT programs that can be attached to
HW and SW perf events (PERF_TYPE_HARDWARE and PERF_TYPE_SOFTWARE
correspondingly in uapi/linux/perf_event.h)
The program visible context meta structure is
struct bpf_perf_event_data {
struct pt_regs regs;
__u64 sample_period;
};
which is accessible directly from the program:
int bpf_prog(struct bpf_perf_event_data *ctx)
{
... ctx->sample_period ...
... ctx->regs.ip ...
}
The bpf verifier rewrites the accesses into kernel internal
struct bpf_perf_event_data_kern which allows changing
struct perf_sample_data without affecting bpf programs.
New fields can be added to the end of struct bpf_perf_event_data
in the future.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
bpf_get_prandom_u32() was initially introduced for socket filters
and later requested numberous times to be added to tracing bpf programs
for the same reason as in socket filters: to be able to randomly
select incoming events.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This adds a bpf helper that's similar to the skb_in_cgroup helper to check
whether the probe is currently executing in the context of a specific
subset of the cgroupsv2 hierarchy. It does this based on membership test
for a cgroup arraymap. It is invalid to call this in an interrupt, and
it'll return an error. The helper is primarily to be used in debugging
activities for containers, where you may have multiple programs running in
a given top-level "container".
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This allows user memory to be written to during the course of a kprobe.
It shouldn't be used to implement any kind of security mechanism
because of TOC-TOU attacks, but rather to debug, divert, and
manipulate execution of semi-cooperative processes.
Although it uses probe_kernel_write, we limit the address space
the probe can write into by checking the space with access_ok.
We do this as opposed to calling copy_to_user directly, in order
to avoid sleeping. In addition we ensure the threads's current fs
/ segment is USER_DS and the thread isn't exiting nor a kernel thread.
Given this feature is meant for experiments, and it has a risk of
crashing the system, and running programs, we print a warning on
when a proglet that attempts to use this helper is installed,
along with the pid and process name.
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
kernel/trace/bpf_trace.c: In function 'bpf_event_output':
kernel/trace/bpf_trace.c:312: error: unknown field 'next' specified in initializer
kernel/trace/bpf_trace.c:312: warning: missing braces around initializer
kernel/trace/bpf_trace.c:312: warning: (near initialization for 'raw.frag.<anonymous>')
Fixes: 555c8a8623 ("bpf: avoid stack copy and use skb ctx for event output")
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This work addresses a couple of issues bpf_skb_event_output()
helper currently has: i) We need two copies instead of just a
single one for the skb data when it should be part of a sample.
The data can be non-linear and thus needs to be extracted via
bpf_skb_load_bytes() helper first, and then copied once again
into the ring buffer slot. ii) Since bpf_skb_load_bytes()
currently needs to be used first, the helper needs to see a
constant size on the passed stack buffer to make sure BPF
verifier can do sanity checks on it during verification time.
Thus, just passing skb->len (or any other non-constant value)
wouldn't work, but changing bpf_skb_load_bytes() is also not
the proper solution, since the two copies are generally still
needed. iii) bpf_skb_load_bytes() is just for rather small
buffers like headers, since they need to sit on the limited
BPF stack anyway. Instead of working around in bpf_skb_load_bytes(),
this work improves the bpf_skb_event_output() helper to address
all 3 at once.
We can make use of the passed in skb context that we have in
the helper anyway, and use some of the reserved flag bits as
a length argument. The helper will use the new __output_custom()
facility from perf side with bpf_skb_copy() as callback helper
to walk and extract the data. It will pass the data for setup
to bpf_event_output(), which generates and pushes the raw record
with an additional frag part. The linear data used in the first
frag of the record serves as programmatically defined meta data
passed along with the appended sample.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Split the bpf_perf_event_output() helper as a preparation into
two parts. The new bpf_perf_event_output() will prepare the raw
record itself and test for unknown flags from BPF trace context,
where the __bpf_perf_event_output() does the core work. The
latter will be reused later on from bpf_event_output() directly.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds support for non-linear data on raw records. It
extends raw records to have one or multiple fragments that will
be written linearly into the ring slot, where each fragment can
optionally have a custom callback handler to walk and extract
complex, possibly non-linear data.
If a callback handler is provided for a fragment, then the new
__output_custom() will be used instead of __output_copy() for
the perf_output_sample() part. perf_prepare_sample() does all
the size calculation only once, so perf_output_sample() doesn't
need to redo the same work anymore, meaning real_size and padding
will be cached in the raw record. The raw record becomes 32 bytes
in size without holes; to not increase it further and to avoid
doing unnecessary recalculations in fast-path, we can reuse
next pointer of the last fragment, idea here is borrowed from
ZERO_OR_NULL_PTR(), which should keep the perf_output_sample()
path for PERF_SAMPLE_RAW minimal.
This facility is needed for BPF's event output helper as a first
user that will, in a follow-up, add an additional perf_raw_frag
to its perf_raw_record in order to be able to more efficiently
dump skb context after a linear head meta data related to it.
skbs can be non-linear and thus need a custom output function to
dump buffers. Currently, the skb data needs to be copied twice;
with the help of __output_custom() this work only needs to be
done once. Future users could be things like XDP/BPF programs
that work on different context though and would thus also have
a different callback function.
The few users of raw records are adapted to initialize their frag
data from the raw record itself, no change in behavior for them.
The code is based upon a PoC diff provided by Peter Zijlstra [1].
[1] http://thread.gmane.org/gmane.linux.network/421294
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Daniel Borkmann