From: Alexei Starovoitov <ast@plumgrid.com>
To: "David S. Miller" <davem@davemloft.net>
Cc: Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andy Lutomirski <luto@amacapital.net>,
Steven Rostedt <rostedt@goodmis.org>,
Daniel Borkmann <dborkman@redhat.com>,
Chema Gonzalez <chema@google.com>,
Eric Dumazet <edumazet@google.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Brendan Gregg <brendan.d.gregg@gmail.com>,
Namhyung Kim <namhyung@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>,
Kees Cook <keescook@chromium.org>,
linux-api@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v5 net-next 09/29] bpf: handle pseudo BPF_CALL insn
Date: Sun, 24 Aug 2014 13:21:10 -0700 [thread overview]
Message-ID: <1408911690-7598-10-git-send-email-ast@plumgrid.com> (raw)
In-Reply-To: <1408911690-7598-1-git-send-email-ast@plumgrid.com>
in native eBPF programs userspace is using pseudo BPF_CALL instructions
which encode one of 'enum bpf_func_id' inside insn->imm field.
Verifier checks that program using correct function arguments to given func_id.
If all checks passed, kernel needs to fixup BPF_CALL->imm fields by
replacing func_id with in-kernel function pointer.
eBPF interpreter just calls the function.
In-kernel eBPF users continue to use generic BPF_CALL.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
---
kernel/bpf/syscall.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 4c5f5169f6fc..5a336af61858 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -338,6 +338,40 @@ void bpf_register_prog_type(struct bpf_prog_type_list *tl)
list_add(&tl->list_node, &bpf_prog_types);
}
+/* fixup insn->imm field of bpf_call instructions:
+ * if (insn->imm == BPF_FUNC_map_lookup_elem)
+ * insn->imm = bpf_map_lookup_elem - __bpf_call_base;
+ * else if (insn->imm == BPF_FUNC_map_update_elem)
+ * insn->imm = bpf_map_update_elem - __bpf_call_base;
+ * else ...
+ *
+ * this function is called after eBPF program passed verification
+ */
+static void fixup_bpf_calls(struct bpf_prog *prog)
+{
+ const struct bpf_func_proto *fn;
+ int i;
+
+ for (i = 0; i < prog->len; i++) {
+ struct bpf_insn *insn = &prog->insnsi[i];
+
+ if (insn->code == (BPF_JMP | BPF_CALL)) {
+ /* we reach here when program has bpf_call instructions
+ * and it passed bpf_check(), means that
+ * ops->get_func_proto must have been supplied, check it
+ */
+ BUG_ON(!prog->info->ops->get_func_proto);
+
+ fn = prog->info->ops->get_func_proto(insn->imm);
+ /* all functions that have prototype and verifier allowed
+ * programs to call them, must be real in-kernel functions
+ */
+ BUG_ON(!fn->func);
+ insn->imm = fn->func - __bpf_call_base;
+ }
+ }
+}
+
/* drop refcnt on maps used by eBPF program and free auxilary data */
static void free_bpf_prog_info(struct bpf_prog_info *info)
{
@@ -485,6 +519,9 @@ static int bpf_prog_load(enum bpf_prog_type type, struct nlattr __user *uattr,
if (err < 0)
goto free_prog_info;
+ /* fixup BPF_CALL->imm field */
+ fixup_bpf_calls(prog);
+
/* eBPF program is ready to be JITed */
bpf_prog_select_runtime(prog);
--
1.7.9.5
next prev parent reply other threads:[~2014-08-24 20:22 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-24 20:21 [PATCH v5 net-next 00/29] BPF syscall, maps, verifier, samples, llvm Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 01/29] bpf: x86: add missing 'shift by register' instructions to x64 eBPF JIT Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 02/29] net: filter: add "load 64-bit immediate" eBPF instruction Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 03/29] net: filter: split filter.h and expose eBPF to user space Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 04/29] bpf: introduce syscall(BPF, ...) and BPF maps Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 05/29] bpf: enable bpf syscall on x64 and i386 Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 06/29] bpf: add lookup/update/delete/iterate methods to BPF maps Alexei Starovoitov
2014-08-25 21:33 ` Cong Wang
2014-08-25 22:07 ` Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 07/29] bpf: add hashtable type of " Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 08/29] bpf: expand BPF syscall with program load/unload Alexei Starovoitov
2014-08-24 20:21 ` Alexei Starovoitov [this message]
2014-08-24 20:21 ` [PATCH v5 net-next 10/29] bpf: verifier (add docs) Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 11/29] bpf: verifier (add ability to receive verification log) Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 12/29] bpf: handle pseudo BPF_LD_IMM64 insn Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 13/29] bpf: verifier (add branch/goto checks) Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 14/29] bpf: verifier (add verifier core) Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 15/29] bpf: verifier (add state prunning optimization) Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 16/29] bpf: allow eBPF programs to use maps Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 17/29] bpf: split eBPF out of NET Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 18/29] tracing: allow eBPF programs to be attached to events Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 19/29] tracing: allow eBPF programs call printk() Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 20/29] tracing: allow eBPF programs to be attached to kprobe/kretprobe Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 21/29] tracing: allow eBPF programs to call ktime_get_ns() and get_current() Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 22/29] samples: bpf: add mini eBPF library to manipulate maps and programs Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 23/29] samples: bpf: example of tracing filters with eBPF Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 24/29] bpf: verifier test Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 25/29] bpf: llvm backend Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 26/29] samples: bpf: elf file loader Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 27/29] samples: bpf: eBPF example in C Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 28/29] samples: bpf: counting " Alexei Starovoitov
2014-08-24 20:21 ` [PATCH v5 net-next 29/29] samples: bpf: IO latency analysis (iosnoop/heatmap) Alexei Starovoitov
2014-08-25 0:39 ` [PATCH v5 net-next 00/29] BPF syscall, maps, verifier, samples, llvm David Miller
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