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author | Alexei Starovoitov <ast@plumgrid.com> | 2015-03-13 21:57:42 +0300 |
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committer | David S. Miller <davem@davemloft.net> | 2015-03-16 05:02:28 +0300 |
commit | 9bac3d6d548e5cc925570b263f35b70a00a00ffd (patch) | |
tree | 00ae5c37fb877d7c2b4fdf5ee0b8fe4837b1d476 /samples/bpf | |
parent | a498cfe990f569dd3766bfc9bfd2a5ee04468cd2 (diff) | |
download | linux-9bac3d6d548e5cc925570b263f35b70a00a00ffd.tar.xz |
bpf: allow extended BPF programs access skb fields
introduce user accessible mirror of in-kernel 'struct sk_buff':
struct __sk_buff {
__u32 len;
__u32 pkt_type;
__u32 mark;
__u32 queue_mapping;
};
bpf programs can do:
int bpf_prog(struct __sk_buff *skb)
{
__u32 var = skb->pkt_type;
which will be compiled to bpf assembler as:
dst_reg = *(u32 *)(src_reg + 4) // 4 == offsetof(struct __sk_buff, pkt_type)
bpf verifier will check validity of access and will convert it to:
dst_reg = *(u8 *)(src_reg + offsetof(struct sk_buff, __pkt_type_offset))
dst_reg &= 7
since skb->pkt_type is a bitfield.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'samples/bpf')
0 files changed, 0 insertions, 0 deletions