From 61023658760032e97869b07d54be9681d2529e77 Mon Sep 17 00:00:00 2001 From: David Ahern Date: Thu, 1 Dec 2016 08:48:04 -0800 Subject: [PATCH] bpf: Add new cgroup attach type to enable sock modifications Add new cgroup based program type, BPF_PROG_TYPE_CGROUP_SOCK. Similar to BPF_PROG_TYPE_CGROUP_SKB programs can be attached to a cgroup and run any time a process in the cgroup opens an AF_INET or AF_INET6 socket. Currently only sk_bound_dev_if is exported to userspace for modification by a bpf program. This allows a cgroup to be configured such that AF_INET{6} sockets opened by processes are automatically bound to a specific device. In turn, this enables the running of programs that do not support SO_BINDTODEVICE in a specific VRF context / L3 domain. Signed-off-by: David Ahern Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/linux/bpf-cgroup.h | 14 +++++++++ include/uapi/linux/bpf.h | 6 ++++ kernel/bpf/cgroup.c | 33 ++++++++++++++++++++ kernel/bpf/syscall.c | 5 ++- net/core/filter.c | 62 ++++++++++++++++++++++++++++++++++++++ net/ipv4/af_inet.c | 12 +++++++- net/ipv6/af_inet6.c | 8 +++++ 7 files changed, 138 insertions(+), 2 deletions(-) diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h index af2ca8b432c0..7b6e5d168c95 100644 --- a/include/linux/bpf-cgroup.h +++ b/include/linux/bpf-cgroup.h @@ -40,6 +40,9 @@ int __cgroup_bpf_run_filter_skb(struct sock *sk, struct sk_buff *skb, enum bpf_attach_type type); +int __cgroup_bpf_run_filter_sk(struct sock *sk, + enum bpf_attach_type type); + /* Wrappers for __cgroup_bpf_run_filter_skb() guarded by cgroup_bpf_enabled. */ #define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk, skb) \ ({ \ @@ -63,6 +66,16 @@ int __cgroup_bpf_run_filter_skb(struct sock *sk, __ret; \ }) +#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) \ +({ \ + int __ret = 0; \ + if (cgroup_bpf_enabled && sk) { \ + __ret = __cgroup_bpf_run_filter_sk(sk, \ + BPF_CGROUP_INET_SOCK_CREATE); \ + } \ + __ret; \ +}) + #else struct cgroup_bpf {}; @@ -72,6 +85,7 @@ static inline void cgroup_bpf_inherit(struct cgroup *cgrp, #define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; }) #define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) ({ 0; }) +#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) ({ 0; }) #endif /* CONFIG_CGROUP_BPF */ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 22ac82792687..bfe5e31a1288 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -101,6 +101,7 @@ enum bpf_prog_type { BPF_PROG_TYPE_XDP, BPF_PROG_TYPE_PERF_EVENT, BPF_PROG_TYPE_CGROUP_SKB, + BPF_PROG_TYPE_CGROUP_SOCK, BPF_PROG_TYPE_LWT_IN, BPF_PROG_TYPE_LWT_OUT, BPF_PROG_TYPE_LWT_XMIT, @@ -109,6 +110,7 @@ enum bpf_prog_type { enum bpf_attach_type { BPF_CGROUP_INET_INGRESS, BPF_CGROUP_INET_EGRESS, + BPF_CGROUP_INET_SOCK_CREATE, __MAX_BPF_ATTACH_TYPE }; @@ -567,6 +569,10 @@ enum bpf_ret_code { /* >127 are reserved for prog type specific return codes */ }; +struct bpf_sock { + __u32 bound_dev_if; +}; + /* User return codes for XDP prog type. * A valid XDP program must return one of these defined values. All other * return codes are reserved for future use. Unknown return codes will result diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index 8fe55ffd109d..a515f7b007c6 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -165,3 +165,36 @@ int __cgroup_bpf_run_filter_skb(struct sock *sk, return ret; } EXPORT_SYMBOL(__cgroup_bpf_run_filter_skb); + +/** + * __cgroup_bpf_run_filter_sk() - Run a program on a sock + * @sk: sock structure to manipulate + * @type: The type of program to be exectuted + * + * socket is passed is expected to be of type INET or INET6. + * + * The program type passed in via @type must be suitable for sock + * filtering. No further check is performed to assert that. + * + * This function will return %-EPERM if any if an attached program was found + * and if it returned != 1 during execution. In all other cases, 0 is returned. + */ +int __cgroup_bpf_run_filter_sk(struct sock *sk, + enum bpf_attach_type type) +{ + struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data); + struct bpf_prog *prog; + int ret = 0; + + + rcu_read_lock(); + + prog = rcu_dereference(cgrp->bpf.effective[type]); + if (prog) + ret = BPF_PROG_RUN(prog, sk) == 1 ? 0 : -EPERM; + + rcu_read_unlock(); + + return ret; +} +EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 5518a6839ab1..85af86c496cd 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -869,7 +869,9 @@ static int bpf_prog_attach(const union bpf_attr *attr) case BPF_CGROUP_INET_EGRESS: ptype = BPF_PROG_TYPE_CGROUP_SKB; break; - + case BPF_CGROUP_INET_SOCK_CREATE: + ptype = BPF_PROG_TYPE_CGROUP_SOCK; + break; default: return -EINVAL; } @@ -905,6 +907,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) switch (attr->attach_type) { case BPF_CGROUP_INET_INGRESS: case BPF_CGROUP_INET_EGRESS: + case BPF_CGROUP_INET_SOCK_CREATE: cgrp = cgroup_get_from_fd(attr->target_fd); if (IS_ERR(cgrp)) return PTR_ERR(cgrp); diff --git a/net/core/filter.c b/net/core/filter.c index 1c4d0faf22c8..0ab252e462aa 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2818,6 +2818,32 @@ static bool lwt_is_valid_access(int off, int size, return __is_valid_access(off, size, type); } +static bool sock_filter_is_valid_access(int off, int size, + enum bpf_access_type type, + enum bpf_reg_type *reg_type) +{ + if (type == BPF_WRITE) { + switch (off) { + case offsetof(struct bpf_sock, bound_dev_if): + break; + default: + return false; + } + } + + if (off < 0 || off + size > sizeof(struct bpf_sock)) + return false; + + /* The verifier guarantees that size > 0. */ + if (off % size != 0) + return false; + + if (size != sizeof(__u32)) + return false; + + return true; +} + static int tc_cls_act_prologue(struct bpf_insn *insn_buf, bool direct_write, const struct bpf_prog *prog) { @@ -3076,6 +3102,30 @@ static u32 sk_filter_convert_ctx_access(enum bpf_access_type type, int dst_reg, return insn - insn_buf; } +static u32 sock_filter_convert_ctx_access(enum bpf_access_type type, + int dst_reg, int src_reg, + int ctx_off, + struct bpf_insn *insn_buf, + struct bpf_prog *prog) +{ + struct bpf_insn *insn = insn_buf; + + switch (ctx_off) { + case offsetof(struct bpf_sock, bound_dev_if): + BUILD_BUG_ON(FIELD_SIZEOF(struct sock, sk_bound_dev_if) != 4); + + if (type == BPF_WRITE) + *insn++ = BPF_STX_MEM(BPF_W, dst_reg, src_reg, + offsetof(struct sock, sk_bound_dev_if)); + else + *insn++ = BPF_LDX_MEM(BPF_W, dst_reg, src_reg, + offsetof(struct sock, sk_bound_dev_if)); + break; + } + + return insn - insn_buf; +} + static u32 tc_cls_act_convert_ctx_access(enum bpf_access_type type, int dst_reg, int src_reg, int ctx_off, struct bpf_insn *insn_buf, @@ -3162,6 +3212,12 @@ static const struct bpf_verifier_ops lwt_xmit_ops = { .gen_prologue = tc_cls_act_prologue, }; +static const struct bpf_verifier_ops cg_sock_ops = { + .get_func_proto = sk_filter_func_proto, + .is_valid_access = sock_filter_is_valid_access, + .convert_ctx_access = sock_filter_convert_ctx_access, +}; + static struct bpf_prog_type_list sk_filter_type __read_mostly = { .ops = &sk_filter_ops, .type = BPF_PROG_TYPE_SOCKET_FILTER, @@ -3202,6 +3258,11 @@ static struct bpf_prog_type_list lwt_xmit_type __read_mostly = { .type = BPF_PROG_TYPE_LWT_XMIT, }; +static struct bpf_prog_type_list cg_sock_type __read_mostly = { + .ops = &cg_sock_ops, + .type = BPF_PROG_TYPE_CGROUP_SOCK +}; + static int __init register_sk_filter_ops(void) { bpf_register_prog_type(&sk_filter_type); @@ -3209,6 +3270,7 @@ static int __init register_sk_filter_ops(void) bpf_register_prog_type(&sched_act_type); bpf_register_prog_type(&xdp_type); bpf_register_prog_type(&cg_skb_type); + bpf_register_prog_type(&cg_sock_type); bpf_register_prog_type(&lwt_in_type); bpf_register_prog_type(&lwt_out_type); bpf_register_prog_type(&lwt_xmit_type); diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 5ddf5cda07f4..24d2550492ee 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -374,8 +374,18 @@ static int inet_create(struct net *net, struct socket *sock, int protocol, if (sk->sk_prot->init) { err = sk->sk_prot->init(sk); - if (err) + if (err) { sk_common_release(sk); + goto out; + } + } + + if (!kern) { + err = BPF_CGROUP_RUN_PROG_INET_SOCK(sk); + if (err) { + sk_common_release(sk); + goto out; + } } out: return err; diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index d424f3a3737a..237e654ba717 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -258,6 +258,14 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol, goto out; } } + + if (!kern) { + err = BPF_CGROUP_RUN_PROG_INET_SOCK(sk); + if (err) { + sk_common_release(sk); + goto out; + } + } out: return err; out_rcu_unlock: