diff options
Diffstat (limited to 'kernel/trace/bpf_trace.c')
| -rw-r--r-- | kernel/trace/bpf_trace.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 52f53a142892..3f49c99bc0e0 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -94,6 +94,35 @@ static const struct bpf_func_proto bpf_probe_read_proto = { .arg3_type = ARG_ANYTHING, }; +BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size, const void *, unsafe_ptr) +{ + int ret; + + /* + * The strncpy_from_unsafe() call will likely not fill the entire + * buffer, but that's okay in this circumstance as we're probing + * arbitrary memory anyway similar to bpf_probe_read() and might + * as well probe the stack. Thus, memory is explicitly cleared + * only in error case, so that improper users ignoring return + * code altogether don't copy garbage; otherwise length of string + * is returned that can be used for bpf_perf_event_output() et al. + */ + ret = strncpy_from_unsafe(dst, unsafe_ptr, size); + if (unlikely(ret < 0)) + memset(dst, 0, size); + + return ret; +} + +static const struct bpf_func_proto bpf_probe_read_str_proto = { + .func = bpf_probe_read_str, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_RAW_STACK, + .arg2_type = ARG_CONST_STACK_SIZE, + .arg3_type = ARG_ANYTHING, +}; + BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src, u32, size) { @@ -451,6 +480,8 @@ static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id) return &bpf_map_delete_elem_proto; case BPF_FUNC_probe_read: return &bpf_probe_read_proto; + case BPF_FUNC_probe_read_str: + return &bpf_probe_read_str_proto; case BPF_FUNC_ktime_get_ns: return &bpf_ktime_get_ns_proto; case BPF_FUNC_tail_call: |