On 9/27/24 03:37, Eduard Zingerman wrote: > On Thu, 2024-09-26 at 09:29 +0200, Viktor Malik wrote: >> Kernel contains highly optimised implementation of traditional string >> operations. Expose them as kfuncs to allow BPF programs leverage the >> kernel implementation instead of needing to reimplement the operations. >> >> These will be very helpful to bpftrace as it now needs to implement all >> the string operations in LLVM IR. > > Note that existing string related helpers take a pointer to a string > and it's maximal length, namely: > - bpf_strtol > - bpf_strtoul > - bpf_snprintf_btf > - bpf_strncmp > > The unbounded variants that are being exposed in this patch-set > (like strcmp) are only safe to use if string is guaranteed to be null terminated. > Verifier does not check this property at the moment (idk how easy/hard > such analysis might be). > > I'd suggest not to expose unbounded variants of string functions. That's a great point, thanks. Let me remove the unbounded variants for now, until we add the null-byte check to the verifier. The bounded variants will still be useful to bpftrace so I'd love to have them added. Viktor > > [...] >
