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  1. 09 12月, 2014 36 次提交
  3. 06 12月, 2014 4 次提交
    • D
      Merge branch 'ebpf-next' · 8d0c4697
      由 David S. Miller 提交于 
      Alexei Starovoitov says:

====================
allow eBPF programs to be attached to sockets

V1->V2:

fixed comments in sample code to state clearly that packet data is accessed
with LD_ABS instructions and not internal skb fields.
Also replaced constants in:
BPF_LD_ABS(BPF_B, 14 + 9 /* R0 = ip->proto */),
with:
BPF_LD_ABS(BPF_B, ETH_HLEN + offsetof(struct iphdr, protocol) /* R0 = ip->proto */),

V1 cover:

Introduce BPF_PROG_TYPE_SOCKET_FILTER type of eBPF programs that can be
attached to sockets with setsockopt().
Allow such programs to access maps via lookup/update/delete helpers.

This feature was previewed by bpf manpage in commit b4fc1a46("Merge branch 'bpf-next'")
Now it can actually run.

1st patch adds LD_ABS/LD_IND instruction verification and
2nd patch adds new setsockopt() flag.
Patches 3-6 are examples in assembler and in C.

Though native eBPF programs are way more powerful than classic filters
(attachable through similar setsockopt() call), they don't have skb field
accessors yet. Like skb->pkt_type, skb->dev->ifindex are not accessible.
There are sevaral ways to achieve that. That will be in the next set of patches.
So in this set native eBPF programs can only read data from packet and
access maps.

The most powerful example is sockex2_kern.c from patch 6 where ~200 lines of C
are compiled into ~300 of eBPF instructions.
It shows how quite complex packet parsing can be done.

LLVM used to build examples is at https://github.com/iovisor/llvm
which is fork of llvm trunk that I'm cleaning up for upstreaming.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      8d0c4697
    • A
      samples: bpf: large eBPF program in C · fbe33108
      由 Alexei Starovoitov 提交于 
      sockex2_kern.c is purposefully large eBPF program in C.
llvm compiles ~200 lines of C code into ~300 eBPF instructions.

It's similar to __skb_flow_dissect() to demonstrate that complex packet parsing
can be done by eBPF.
Then it uses (struct flow_keys)->dst IP address (or hash of ipv6 dst) to keep
stats of number of packets per IP.
User space loads eBPF program, attaches it to loopback interface and prints
dest_ip->#packets stats every second.

Usage:
$sudo samples/bpf/sockex2
ip 127.0.0.1 count 19
ip 127.0.0.1 count 178115
ip 127.0.0.1 count 369437
ip 127.0.0.1 count 559841
ip 127.0.0.1 count 750539
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      fbe33108
    • A
      samples: bpf: trivial eBPF program in C · a8085782
      由 Alexei Starovoitov 提交于 
      this example does the same task as previous socket example
in assembler, but this one does it in C.

eBPF program in kernel does:
    /* assume that packet is IPv4, load one byte of IP->proto */
    int index = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol));
    long *value;

    value = bpf_map_lookup_elem(&my_map, &index);
    if (value)
        __sync_fetch_and_add(value, 1);

Corresponding user space reads map[tcp], map[udp], map[icmp]
and prints protocol stats every second
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a8085782
    • A
      samples: bpf: elf_bpf file loader · 249b812d
      由 Alexei Starovoitov 提交于 
      simple .o parser and loader using BPF syscall.
.o is a standard ELF generated by LLVM backend

It parses elf file compiled by llvm .c->.o
- parses 'maps' section and creates maps via BPF syscall
- parses 'license' section and passes it to syscall
- parses elf relocations for BPF maps and adjusts BPF_LD_IMM64 insns
  by storing map_fd into insn->imm and marking such insns as BPF_PSEUDO_MAP_FD
- loads eBPF programs via BPF syscall

One ELF file can contain multiple BPF programs.

int load_bpf_file(char *path);
populates prog_fd[] and map_fd[] with FDs received from bpf syscall

bpf_helpers.h - helper functions available to eBPF programs written in C
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      249b812d