Re: [PATCH] Support for nlattr and nested_nlattr attribute search in EBPF filter
From: Daniel Borkmann <daniel@iogearbox.net>
Date: 2020-01-23 15:57:54
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bpf, lkml
On 1/23/20 2:08 PM, Kalimuthu Velappan wrote:
Added attribute search and nested attribute support in EBPF filter functionality.
Your commit describes what the code does, but not the rationale why it's needed resp. the use-case you're trying to solve with this. Also, why it cannot be resolved in native BPF?
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Signed-off-by: Kalimuthu Velappan <redacted> --- include/uapi/linux/bpf.h | 5 ++++- net/core/filter.c | 22 ++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 4 +++- 3 files changed, 29 insertions(+), 2 deletions(-)diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index dbbcf0b..ac9794c 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h@@ -2938,7 +2938,10 @@ union bpf_attr { FN(probe_read_user), \ FN(probe_read_kernel), \ FN(probe_read_user_str), \ - FN(probe_read_kernel_str), + FN(probe_read_kernel_str), \ + FN(skb_get_nlattr), \ + FN(skb_get_nlattr_nest), +
This is not on latest bpf-next tree.
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/* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to calldiff --git a/net/core/filter.c b/net/core/filter.c index 538f6a7..56a87e1 100644 --- a/net/core/filter.c +++ b/net/core/filter.c@@ -2699,6 +2699,24 @@ static const struct bpf_func_proto bpf_set_hash_invalid_proto = { .arg1_type = ARG_PTR_TO_CTX, }; +static const struct bpf_func_proto bpf_skb_get_nlattr_proto = { + .func = bpf_skb_get_nlattr, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, + .arg3_type = ARG_ANYTHING, +}; + +static const struct bpf_func_proto skb_get_nlattr_nest_proto = { + .func = bpf_skb_get_nlattr_nest, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, + .arg3_type = ARG_ANYTHING, +}; + BPF_CALL_2(bpf_set_hash, struct sk_buff *, skb, u32, hash)