From 62544ce8e01c1879d420ba309f7f319d24c0f4e6 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 22 Oct 2015 17:10:14 -0700 Subject: [PATCH] bpf: fix bpf_perf_event_read() helper Fix safety checks for bpf_perf_event_read(): - only non-inherited events can be added to perf_event_array map (do this check statically at map insertion time) - dynamically check that event is local and !pmu->count Otherwise buggy bpf program can cause kernel splat. Also fix error path after perf_event_attrs() and remove redundant 'extern'. Fixes: 35578d798400 ("bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter") Signed-off-by: Alexei Starovoitov Tested-by: Wang Nan Signed-off-by: David S. Miller --- include/linux/bpf.h | 1 - kernel/bpf/arraymap.c | 25 ++++++++++++++++--------- kernel/trace/bpf_trace.c | 7 ++++++- 3 files changed, 22 insertions(+), 11 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index e3a51b74e275..75718fa28260 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -194,7 +194,6 @@ extern const struct bpf_func_proto bpf_map_lookup_elem_proto; extern const struct bpf_func_proto bpf_map_update_elem_proto; extern const struct bpf_func_proto bpf_map_delete_elem_proto; -extern const struct bpf_func_proto bpf_perf_event_read_proto; extern const struct bpf_func_proto bpf_get_prandom_u32_proto; extern const struct bpf_func_proto bpf_get_smp_processor_id_proto; extern const struct bpf_func_proto bpf_tail_call_proto; diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index e3cfe46b074f..3f4c99e06c6b 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -292,16 +292,23 @@ static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd) attr = perf_event_attrs(event); if (IS_ERR(attr)) - return (void *)attr; + goto err; - if (attr->type != PERF_TYPE_RAW && - !(attr->type == PERF_TYPE_SOFTWARE && - attr->config == PERF_COUNT_SW_BPF_OUTPUT) && - attr->type != PERF_TYPE_HARDWARE) { - perf_event_release_kernel(event); - return ERR_PTR(-EINVAL); - } - return event; + if (attr->inherit) + goto err; + + if (attr->type == PERF_TYPE_RAW) + return event; + + if (attr->type == PERF_TYPE_HARDWARE) + return event; + + if (attr->type == PERF_TYPE_SOFTWARE && + attr->config == PERF_COUNT_SW_BPF_OUTPUT) + return event; +err: + perf_event_release_kernel(event); + return ERR_PTR(-EINVAL); } static void perf_event_fd_array_put_ptr(void *ptr) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 47febbe7998e..003df3887287 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -199,6 +199,11 @@ static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5) if (!event) return -ENOENT; + /* make sure event is local and doesn't have pmu::count */ + if (event->oncpu != smp_processor_id() || + event->pmu->count) + return -EINVAL; + /* * we don't know if the function is run successfully by the * return value. It can be judged in other places, such as @@ -207,7 +212,7 @@ static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5) return perf_event_read_local(event); } -const struct bpf_func_proto bpf_perf_event_read_proto = { +static const struct bpf_func_proto bpf_perf_event_read_proto = { .func = bpf_perf_event_read, .gpl_only = false, .ret_type = RET_INTEGER, -- 2.39.2