diff options
author | Daniel Borkmann <daniel@iogearbox.net> | 2017-12-12 02:25:30 +0100 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2017-12-12 18:51:12 +0100 |
commit | 283ca526a9bd75aed7350220d7b1f8027d99c3fd (patch) | |
tree | e702c33467d5fc7b2c3b807addc3269774b9f40c /kernel | |
parent | tcp md5sig: Use skb's saddr when replying to an incoming segment (diff) | |
download | linux-283ca526a9bd75aed7350220d7b1f8027d99c3fd.tar.xz linux-283ca526a9bd75aed7350220d7b1f8027d99c3fd.zip |
bpf: fix corruption on concurrent perf_event_output calls
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: 20b9d7ac4852 ("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>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/trace/bpf_trace.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 0ce99c379c30..40207c2a4113 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -343,14 +343,13 @@ static const struct bpf_func_proto bpf_perf_event_read_value_proto = { .arg4_type = ARG_CONST_SIZE, }; -static DEFINE_PER_CPU(struct perf_sample_data, bpf_sd); +static DEFINE_PER_CPU(struct perf_sample_data, bpf_trace_sd); static __always_inline u64 __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map, - u64 flags, struct perf_raw_record *raw) + u64 flags, struct perf_sample_data *sd) { struct bpf_array *array = container_of(map, struct bpf_array, map); - struct perf_sample_data *sd = this_cpu_ptr(&bpf_sd); unsigned int cpu = smp_processor_id(); u64 index = flags & BPF_F_INDEX_MASK; struct bpf_event_entry *ee; @@ -373,8 +372,6 @@ __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map, if (unlikely(event->oncpu != cpu)) return -EOPNOTSUPP; - perf_sample_data_init(sd, 0, 0); - sd->raw = raw; perf_event_output(event, sd, regs); return 0; } @@ -382,6 +379,7 @@ __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map, BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map, u64, flags, void *, data, u64, size) { + struct perf_sample_data *sd = this_cpu_ptr(&bpf_trace_sd); struct perf_raw_record raw = { .frag = { .size = size, @@ -392,7 +390,10 @@ BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map, if (unlikely(flags & ~(BPF_F_INDEX_MASK))) return -EINVAL; - return __bpf_perf_event_output(regs, map, flags, &raw); + perf_sample_data_init(sd, 0, 0); + sd->raw = &raw; + + return __bpf_perf_event_output(regs, map, flags, sd); } static const struct bpf_func_proto bpf_perf_event_output_proto = { @@ -407,10 +408,12 @@ static const struct bpf_func_proto bpf_perf_event_output_proto = { }; static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs); +static DEFINE_PER_CPU(struct perf_sample_data, bpf_misc_sd); u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size, void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy) { + struct perf_sample_data *sd = this_cpu_ptr(&bpf_misc_sd); struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs); struct perf_raw_frag frag = { .copy = ctx_copy, @@ -428,8 +431,10 @@ u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size, }; perf_fetch_caller_regs(regs); + perf_sample_data_init(sd, 0, 0); + sd->raw = &raw; - return __bpf_perf_event_output(regs, map, flags, &raw); + return __bpf_perf_event_output(regs, map, flags, sd); } BPF_CALL_0(bpf_get_current_task) |