Re: [PATCH bpf-next 2/8] bpf: Add user memory kfuncs

[Jiri Olsa <olsajiri@gmail.com>]

On Thu, Oct 29, 2026 at 03:00:50PM -0700, Andrii Nakryiko wrote:
> On Thu, Oct 29, 2026 at 2:26 PM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > Add sleepable kfuncs to copy data into a task's address space and to map
> > or unmap private anonymous memory in the current process.
> >
> > Require a usable user mm for mmap and munmap. Register the kfuncs for
> > KPROBE programs and gate them on CAP_SYS_ADMIN BPF token capability and
> > the BPF_WRITE_USER lockdown check.
> >
> > Use FOLL_FORCE | FOLL_WRITE for task memory copies and return -EFAULT
> > when a copy is incomplete.
> >
> > Rename the syscall info-copy helper to bpf_copy_to_user_buf to avoid
> > the name collision.
> >
> > Assisted-by: Codex:GPT-6
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> >  kernel/bpf/helpers.c | 102 +++++++++++++++++++++++++++++++++++++++++++
> >  kernel/bpf/syscall.c |  10 ++---
> >  2 files changed, 107 insertions(+), 5 deletions(-)
> >
> 
> [...]
> 
> > +/**
> > + * bpf_user_mmap() - Map private anonymous memory into the current process
> > + * @len:  Length of the mapping
> > + * @prot: PROT_* flags of mmap(2), including PROT_EXEC
> > + *
> > + * This maps memory by calling vm_mmap() directly. It does not invoke the
> > + * mmap(2) syscall, so seccomp filters do not mediate this mapping.
> > + *
> > + * Return: The address of the mapping on success, -EPERM if the caller has no
> > + * user mm, or an unsigned-long encoded negative error code, as returned by
> > + * vm_mmap().
> > + */
> > +__bpf_kfunc unsigned long bpf_user_mmap(unsigned long len, unsigned long prot)
> 
> bpf_user_anon_mmap(), so we can conceivably have a more generic
> bpf_user_mmap(struct file*, ...) in the future?

yes, will change

thanks,
jirka