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author | Joanne Koong <joannelkoong@gmail.com> | 2023-03-01 07:49:50 -0800 |
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committer | Alexei Starovoitov <ast@kernel.org> | 2023-03-01 09:55:24 -0800 |
commit | b5964b968ac64c2ec2debee7518499113b27c34e (patch) | |
tree | a0865b41439109704eade0e03ff33097100d52ee /net/core/filter.c | |
parent | d96d937d7c5c12237dce1f14bf0fc9900cabba09 (diff) | |
download | linux-b5964b968ac64c2ec2debee7518499113b27c34e.tar.gz linux-b5964b968ac64c2ec2debee7518499113b27c34e.tar.xz |
bpf: Add skb dynptrs
Add skb dynptrs, which are dynptrs whose underlying pointer points
to a skb. The dynptr acts on skb data. skb dynptrs have two main
benefits. One is that they allow operations on sizes that are not
statically known at compile-time (eg variable-sized accesses).
Another is that parsing the packet data through dynptrs (instead of
through direct access of skb->data and skb->data_end) can be more
ergonomic and less brittle (eg does not need manual if checking for
being within bounds of data_end).
For bpf prog types that don't support writes on skb data, the dynptr is
read-only (bpf_dynptr_write() will return an error)
For reads and writes through the bpf_dynptr_read() and bpf_dynptr_write()
interfaces, reading and writing from/to data in the head as well as from/to
non-linear paged buffers is supported. Data slices through the
bpf_dynptr_data API are not supported; instead bpf_dynptr_slice() and
bpf_dynptr_slice_rdwr() (added in subsequent commit) should be used.
For examples of how skb dynptrs can be used, please see the attached
selftests.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://lore.kernel.org/r/20230301154953.641654-8-joannelkoong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net/core/filter.c')
-rw-r--r-- | net/core/filter.c | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 1d6f165923bf..f3afa31a9b10 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1721,6 +1721,12 @@ static const struct bpf_func_proto bpf_skb_store_bytes_proto = { .arg5_type = ARG_ANYTHING, }; +int __bpf_skb_store_bytes(struct sk_buff *skb, u32 offset, const void *from, + u32 len, u64 flags) +{ + return ____bpf_skb_store_bytes(skb, offset, from, len, flags); +} + BPF_CALL_4(bpf_skb_load_bytes, const struct sk_buff *, skb, u32, offset, void *, to, u32, len) { @@ -1751,6 +1757,11 @@ static const struct bpf_func_proto bpf_skb_load_bytes_proto = { .arg4_type = ARG_CONST_SIZE, }; +int __bpf_skb_load_bytes(const struct sk_buff *skb, u32 offset, void *to, u32 len) +{ + return ____bpf_skb_load_bytes(skb, offset, to, len); +} + BPF_CALL_4(bpf_flow_dissector_load_bytes, const struct bpf_flow_dissector *, ctx, u32, offset, void *, to, u32, len) @@ -11621,3 +11632,59 @@ bpf_sk_base_func_proto(enum bpf_func_id func_id) return func; } + +__diag_push(); +__diag_ignore_all("-Wmissing-prototypes", + "Global functions as their definitions will be in vmlinux BTF"); +__bpf_kfunc int bpf_dynptr_from_skb(struct sk_buff *skb, u64 flags, + struct bpf_dynptr_kern *ptr__uninit) +{ + if (flags) { + bpf_dynptr_set_null(ptr__uninit); + return -EINVAL; + } + + bpf_dynptr_init(ptr__uninit, skb, BPF_DYNPTR_TYPE_SKB, 0, skb->len); + + return 0; +} +__diag_pop(); + +int bpf_dynptr_from_skb_rdonly(struct sk_buff *skb, u64 flags, + struct bpf_dynptr_kern *ptr__uninit) +{ + int err; + + err = bpf_dynptr_from_skb(skb, flags, ptr__uninit); + if (err) + return err; + + bpf_dynptr_set_rdonly(ptr__uninit); + + return 0; +} + +BTF_SET8_START(bpf_kfunc_check_set_skb) +BTF_ID_FLAGS(func, bpf_dynptr_from_skb) +BTF_SET8_END(bpf_kfunc_check_set_skb) + +static const struct btf_kfunc_id_set bpf_kfunc_set_skb = { + .owner = THIS_MODULE, + .set = &bpf_kfunc_check_set_skb, +}; + +static int __init bpf_kfunc_init(void) +{ + int ret; + + ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_kfunc_set_skb); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_ACT, &bpf_kfunc_set_skb); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SK_SKB, &bpf_kfunc_set_skb); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SOCKET_FILTER, &bpf_kfunc_set_skb); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SKB, &bpf_kfunc_set_skb); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_OUT, &bpf_kfunc_set_skb); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_IN, &bpf_kfunc_set_skb); + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_XMIT, &bpf_kfunc_set_skb); + return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_SEG6LOCAL, &bpf_kfunc_set_skb); +} +late_initcall(bpf_kfunc_init); |