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author | Daniel Borkmann <daniel@iogearbox.net> | 2015-03-14 02:27:16 +0100 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2015-03-15 21:57:25 -0400 |
commit | 03e69b508b6f7c51743055c9f61d1dfeadf4b635 (patch) | |
tree | 4c9199cde0fe876871e20352666d40721d4c1d5f /kernel | |
parent | 12028820423bd7705beb5e09889faab95c545ea1 (diff) | |
download | op-kernel-dev-03e69b508b6f7c51743055c9f61d1dfeadf4b635.zip op-kernel-dev-03e69b508b6f7c51743055c9f61d1dfeadf4b635.tar.gz |
ebpf: add prandom helper for packet sampling
This work is similar to commit 4cd3675ebf74 ("filter: added BPF
random opcode") and adds a possibility for packet sampling in eBPF.
Currently, this is only possible in classic BPF and useful to
combine sampling with f.e. packet sockets, possible also with tc.
Example function proto-type looks like:
u32 (*prandom_u32)(void) = (void *)BPF_FUNC_get_prandom_u32;
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/bpf/core.c | 2 | ||||
-rw-r--r-- | kernel/bpf/helpers.c | 12 |
2 files changed, 14 insertions, 0 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 50603ae..c1dbbb5d 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -661,6 +661,8 @@ const struct bpf_func_proto bpf_map_lookup_elem_proto __weak; const struct bpf_func_proto bpf_map_update_elem_proto __weak; const struct bpf_func_proto bpf_map_delete_elem_proto __weak; +const struct bpf_func_proto bpf_get_prandom_u32_proto __weak; + /* To execute LD_ABS/LD_IND instructions __bpf_prog_run() may call * skb_copy_bits(), so provide a weak definition of it for NET-less config. */ diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index a3c7701..95eb59a 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -11,6 +11,7 @@ */ #include <linux/bpf.h> #include <linux/rcupdate.h> +#include <linux/random.h> /* If kernel subsystem is allowing eBPF programs to call this function, * inside its own verifier_ops->get_func_proto() callback it should return @@ -87,3 +88,14 @@ const struct bpf_func_proto bpf_map_delete_elem_proto = { .arg1_type = ARG_CONST_MAP_PTR, .arg2_type = ARG_PTR_TO_MAP_KEY, }; + +static u64 bpf_get_prandom_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) +{ + return prandom_u32(); +} + +const struct bpf_func_proto bpf_get_prandom_u32_proto = { + .func = bpf_get_prandom_u32, + .gpl_only = false, + .ret_type = RET_INTEGER, +}; |