KFunc bpf_cast_to_kern_ctx
Definition
void *bpf_cast_to_kern_ctx(void *obj)
Usage
The purpose of this kfunc is to cast the UAPI context programs get by default, into a kernel pointer that is allowed to access the kernel type.
So for example an BPF_PROG_TYPE_SCHED_CLS program would get a struct __sk_buff* as the context, passing it to this kfunc would return a struct sk_buff* which is less stable but has more fields. CO-RE should be used to access the fields of the struct sk_buff* to ensure the program is compatible with different kernel versions.
Program types
The following program types can make use of this kfunc:
BPF_PROG_TYPE_CGROUP_SKBBPF_PROG_TYPE_CGROUP_SOCK_ADDRBPF_PROG_TYPE_LSMBPF_PROG_TYPE_LWT_INBPF_PROG_TYPE_LWT_OUTBPF_PROG_TYPE_LWT_SEG6LOCALBPF_PROG_TYPE_LWT_XMITBPF_PROG_TYPE_NETFILTERBPF_PROG_TYPE_SCHED_ACTBPF_PROG_TYPE_SCHED_CLSBPF_PROG_TYPE_SK_SKBBPF_PROG_TYPE_SOCKET_FILTERBPF_PROG_TYPE_STRUCT_OPSBPF_PROG_TYPE_SYSCALLBPF_PROG_TYPE_TRACINGBPF_PROG_TYPE_XDP
Example
Docs could be improved
This part of the docs is incomplete, contributions are very welcome