On 09/11/2015 02:21 AM, Tycho Andersen wrote:
This commit adds a way to dump eBPF programs. The initial implementation
doesn't support maps, and therefore only allows dumping seccomp ebpf
programs which themselves don't currently support maps.
v2: don't export a prog_id for the filter
Signed-off-by: Tycho Andersen <tycho.andersen@xxxxxxxxxxxxx>
CC: Kees Cook <keescook@xxxxxxxxxxxx>
CC: Will Drewry <wad@xxxxxxxxxxxx>
CC: Oleg Nesterov <oleg@xxxxxxxxxx>
CC: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
CC: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
CC: Serge E. Hallyn <serge.hallyn@xxxxxxxxxx>
CC: Alexei Starovoitov <ast@xxxxxxxxxx>
CC: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
[...]
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index dc9b464..58ae9f4 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -586,6 +586,44 @@ free_prog:
return err;
}
+static int bpf_prog_dump(union bpf_attr *attr, union bpf_attr __user *uattr)
+{
+ int ufd = attr->prog_fd;
+ struct fd f = fdget(ufd);
+ struct bpf_prog *prog;
+ int ret = -EINVAL;
+
+ prog = get_prog(f);
+ if (IS_ERR(prog))
+ return PTR_ERR(prog);
+
+ /* For now, let's refuse to dump anything that isn't a seccomp program.
+ * Other program types have support for maps, which our current dump
+ * code doesn't support.
+ */
+ if (prog->type != BPF_PROG_TYPE_SECCOMP)
+ goto out;
Yep, also when you start adding helper calls (next to map objects) you'd
need to undo kernel pointers that the verifier sets here.
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