net: filter: cleanup invocation of internal BPF

Kernel API for classic BPF socket filters is:

sk_unattached_filter_create() - validate classic BPF, convert, JIT
SK_RUN_FILTER() - run it
sk_unattached_filter_destroy() - destroy socket filter

Cleanup internal BPF kernel API as following:

sk_filter_select_runtime() - final step of internal BPF creation.
  Try to JIT internal BPF program, if JIT is not available select interpreter
SK_RUN_FILTER() - run it
sk_filter_free() - free internal BPF program

Disallow direct calls to BPF interpreter. Execution of the BPF program should
be done with SK_RUN_FILTER() macro.

Example of internal BPF create, run, destroy:

  struct sk_filter *fp;

  fp = kzalloc(sk_filter_size(prog_len), GFP_KERNEL);
  memcpy(fp->insni, prog, prog_len * sizeof(fp->insni[0]));
  fp->len = prog_len;

  sk_filter_select_runtime(fp);

  SK_RUN_FILTER(fp, ctx);

  sk_filter_free(fp);

Sockets, seccomp, testsuite, tracing are using different ways to populate
sk_filter, so first steps of program creation are not common.

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 4 deletions

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 7e02d624cc50..1036b6f2fded 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -273,10 +273,8 @@ static long seccomp_attach_filter(struct sock_fprog *fprog)
 
 	atomic_set(&filter->usage, 1);
 	filter->prog->len = new_len;
-	filter->prog->bpf_func = (void *)sk_run_filter_int_seccomp;
 
-	/* JIT internal BPF into native HW instructions */
-	bpf_int_jit_compile(filter->prog);
+	sk_filter_select_runtime(filter->prog);
 
 	/*
 	 * If there is an existing filter, make it the prev and don't drop its
@@ -340,7 +338,7 @@ void put_seccomp_filter(struct task_struct *tsk)
 	while (orig && atomic_dec_and_test(&orig->usage)) {
 		struct seccomp_filter *freeme = orig;
 		orig = orig->prev;
-		bpf_jit_free(freeme->prog);
+		sk_filter_free(freeme->prog);
 		kfree(freeme);
 	}
 }