Attaching uprobes with special characters in function names fails

[stevenjohnstone]

What reproduces the bug?

Using version bpftrace v0.16.0-20-g720b try to attach to a uprobe to a golang function e.g.

uprobe:"/home/stevie/code/go-bpf-gen/tests/tests":"crypto/rand.(*devReader).Read" {

}

This fails with

ERROR: Error loading program: uprobe:/home/stevie/code/go-bpf-gen/tests/tests:crypto/rand.(*devReader).Read (try -v)

With strace I see

bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_KPROBE, insn_cnt=29, insns=0x55c0cf700040, license="GPL", log_level=1, log_size=1000000, log_buf="", kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0, prog_name="crypto/rand.(*d", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=0, func_info_rec_size=0, func_info=NULL, func_info_cnt=0, line_info_rec_size=0, line_info=NULL, line_info_cnt=0, attach_btf_id=0, attach_prog_fd=0, fd_array=NULL}, 128) = -1 EINVAL (Invalid argument)

It looks like there are symbols in prog_name="crypto/rand.(*d which will be rejected.

The last working revision seems to be 5ab53fa, just before changes to replace bcc loading with libbpf.

This patch fixes the issue for me:

diff --git a/src/attached_probe.cpp b/src/attached_probe.cpp
index 1e079039..2ef23ba3 100644
--- a/src/attached_probe.cpp
+++ b/src/attached_probe.cpp
@@ -690,11 +690,7 @@ void AttachedProbe::load_prog(BPFfeature &feature)
     // start the name after the probe type, after ':'
     if (auto last_colon = name.rfind(':'); last_colon != std::string::npos)
       name = name.substr(last_colon + 1);
-    // replace '+' and ',' by '.'
-    std::replace(name.begin(), name.end(), '+', '.');
-    std::replace(name.begin(), name.end(), ',', '.');
-    // remove quotes
-    name.erase(std::remove(name.begin(), name.end(), '"'), name.end());
+    name = sanitise(name);
 
     auto prog_type = progtype(probe_.type);
     if (probe_.type == ProbeType::special && !feature.has_raw_tp_special())

bpftrace --info

[viktormalik]

Your patch looks good, could you submit it as a PR? Thanks!