From: Chenbo Feng <fe...@google.com> Returns the owner uid of the socket inside a sk_buff. This is useful to perform per-UID accounting of network traffic or per-UID packet filtering. The socket need to be a fullsock otherwise 0 is returned.
Change since V2: Add a sk_to_full_sk() check before retrieving the uid. Moved the helper function from bpf_base_func_proto() to both sk_filter_func_proto() and tc_cls_act_func_proto(). Add function name to uapi header file under tools/include Change since V1: Removed the unnecessary declarations and export command, resolved conflict with master branch. Examine if the socket is a full socket before getting the uid. Signed-off-by: Chenbo Feng <chenbofeng.ker...@gmail.com> --- include/uapi/linux/bpf.h | 9 ++++++++- net/core/filter.c | 19 +++++++++++++++++++ tools/include/uapi/linux/bpf.h | 3 ++- 3 files changed, 29 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index dc81a9f..ff42111 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -462,6 +462,12 @@ union bpf_attr { * @skb: pointer to skb * Return: 8 Bytes non-decreasing number on success or 0 if the socket * field is missing inside sk_buff + * + * u32 bpf_get_socket_uid(skb) + * Get the owner uid of the socket stored inside sk_buff. + * @skb: pointer to skb + * Return: uid of the socket owner on success or 0 if the socket pointer + * inside sk_buff is NULL */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -510,7 +516,8 @@ union bpf_attr { FN(skb_change_head), \ FN(xdp_adjust_head), \ FN(probe_read_str), \ - FN(get_socket_cookie), + FN(get_socket_cookie), \ + FN(get_socket_uid), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call diff --git a/net/core/filter.c b/net/core/filter.c index 06263c0..53c4afc 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2612,6 +2612,21 @@ static const struct bpf_func_proto bpf_get_socket_cookie_proto = { .arg1_type = ARG_PTR_TO_CTX, }; +BPF_CALL_1(bpf_get_socket_uid, struct sk_buff *, skb) +{ + struct sock *sk = sk_to_full_sk(skb->sk); + kuid_t kuid = sock_net_uid(dev_net(skb->dev), sk); + + return (u32)kuid.val; +} + +static const struct bpf_func_proto bpf_get_socket_uid_proto = { + .func = bpf_get_socket_uid, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, +}; + static const struct bpf_func_proto * bpf_base_func_proto(enum bpf_func_id func_id) { @@ -2648,6 +2663,8 @@ sk_filter_func_proto(enum bpf_func_id func_id) return &bpf_skb_load_bytes_proto; case BPF_FUNC_get_socket_cookie: return &bpf_get_socket_cookie_proto; + case BPF_FUNC_get_socket_uid: + return &bpf_get_socket_uid_proto; default: return bpf_base_func_proto(func_id); } @@ -2709,6 +2726,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id) return &bpf_skb_under_cgroup_proto; case BPF_FUNC_get_socket_cookie: return &bpf_get_socket_cookie_proto; + case BPF_FUNC_get_socket_uid: + return &bpf_get_socket_uid_proto; default: return bpf_base_func_proto(func_id); } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index a94bdd3..4a2d56d 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -504,7 +504,8 @@ union bpf_attr { FN(skb_change_head), \ FN(xdp_adjust_head), \ FN(probe_read_str), \ - FN(get_socket_cookie), + FN(get_socket_cookie), \ + FN(get_socket_uid), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call -- 2.7.4