When loading a BPF program via bpf(2), calculate the digest over
the program's instruction stream and store it in struct bpf_prog's
digest member. This is done at a point in time before any instructions
are rewritten by the verifier. Any unstable map file descriptor
number part of the imm field will be zeroed for the hash.
fdinfo example output for progs:
# cat /proc/1590/fdinfo/5
pos: 0
flags: 02000002
mnt_id: 11
prog_type: 1
prog_jited: 1
prog_digest: b27e8b06da22707513aa97363dfb11c7c3675d28
memlock: 4096
When programs are pinned and retrieved by an ELF loader, the loader
can check the program's digest through fdinfo and compare it against
one that was generated over the ELF file's program section to see
if the program needs to be reloaded. Furthermore, this can also be
exposed through other means such as netlink in case of a tc cls/act
dump (or xdp in future), but also through tracepoints or other
facilities to identify the program. Other than that, the digest can
also serve as a base name for the work in progress kallsyms support
of programs. The digest doesn't depend/select the crypto layer, since
we need to keep dependencies to a minimum. iproute2 will get support
for this facility.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This work extends the "classic" BPF programmable tc action by extending
its scope also to native eBPF code!
Together with commit e2e9b6541d ("cls_bpf: add initial eBPF support
for programmable classifiers") this adds the facility to implement fully
flexible classifier and actions for tc that can be implemented in a C
subset in user space, "safely" loaded into the kernel, and being run in
native speed when JITed.
Also, since eBPF maps can be shared between eBPF programs, it offers the
possibility that cls_bpf and act_bpf can share data 1) between themselves
and 2) between user space applications. That means that, f.e. customized
runtime statistics can be collected in user space, but also more importantly
classifier and action behaviour could be altered based on map input from
the user space application.
For the remaining details on the workflow and integration, see the cls_bpf
commit e2e9b6541d. Preliminary iproute2 part can be found under [1].
[1] http://git.breakpoint.cc/cgit/dborkman/iproute2.git/log/?h=ebpf-act
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Acked-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This action provides a possibility to exec custom BPF code.
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
Daniel Borkmann