diff options
| -rw-r--r-- | include/linux/bpf-cgroup.h | 79 | ||||
| -rw-r--r-- | include/linux/cgroup-defs.h | 4 | ||||
| -rw-r--r-- | init/Kconfig | 12 | ||||
| -rw-r--r-- | kernel/bpf/Makefile | 1 | ||||
| -rw-r--r-- | kernel/bpf/cgroup.c | 167 | ||||
| -rw-r--r-- | kernel/cgroup.c | 18 |
6 files changed, 281 insertions, 0 deletions
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h new file mode 100644 index 0000000..ec80d0c --- /dev/null +++ b/include/linux/bpf-cgroup.h @@ -0,0 +1,79 @@ +#ifndef _BPF_CGROUP_H +#define _BPF_CGROUP_H + +#include <linux/bpf.h> +#include <linux/jump_label.h> +#include <uapi/linux/bpf.h> + +struct sock; +struct cgroup; +struct sk_buff; + +#ifdef CONFIG_CGROUP_BPF + +extern struct static_key_false cgroup_bpf_enabled_key; +#define cgroup_bpf_enabled static_branch_unlikely(&cgroup_bpf_enabled_key) + +struct cgroup_bpf { + /* + * Store two sets of bpf_prog pointers, one for programs that are + * pinned directly to this cgroup, and one for those that are effective + * when this cgroup is accessed. + */ + struct bpf_prog *prog[MAX_BPF_ATTACH_TYPE]; + struct bpf_prog *effective[MAX_BPF_ATTACH_TYPE]; +}; + +void cgroup_bpf_put(struct cgroup *cgrp); +void cgroup_bpf_inherit(struct cgroup *cgrp, struct cgroup *parent); + +void __cgroup_bpf_update(struct cgroup *cgrp, + struct cgroup *parent, + struct bpf_prog *prog, + enum bpf_attach_type type); + +/* Wrapper for __cgroup_bpf_update() protected by cgroup_mutex */ +void cgroup_bpf_update(struct cgroup *cgrp, + struct bpf_prog *prog, + enum bpf_attach_type type); + +int __cgroup_bpf_run_filter(struct sock *sk, + struct sk_buff *skb, + enum bpf_attach_type type); + +/* Wrappers for __cgroup_bpf_run_filter() guarded by cgroup_bpf_enabled. */ +#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) \ +({ \ + int __ret = 0; \ + if (cgroup_bpf_enabled) \ + __ret = __cgroup_bpf_run_filter(sk, skb, \ + BPF_CGROUP_INET_INGRESS); \ + \ + __ret; \ +}) + +#define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) \ +({ \ + int __ret = 0; \ + if (cgroup_bpf_enabled && sk && sk == skb->sk) { \ + typeof(sk) __sk = sk_to_full_sk(sk); \ + if (sk_fullsock(__sk)) \ + __ret = __cgroup_bpf_run_filter(__sk, skb, \ + BPF_CGROUP_INET_EGRESS); \ + } \ + __ret; \ +}) + +#else + +struct cgroup_bpf {}; +static inline void cgroup_bpf_put(struct cgroup *cgrp) {} +static inline void cgroup_bpf_inherit(struct cgroup *cgrp, + struct cgroup *parent) {} + +#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; }) +#define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) ({ 0; }) + +#endif /* CONFIG_CGROUP_BPF */ + +#endif /* _BPF_CGROUP_H */ diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 5b17de6..861b467 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -16,6 +16,7 @@ #include <linux/percpu-refcount.h> #include <linux/percpu-rwsem.h> #include <linux/workqueue.h> +#include <linux/bpf-cgroup.h> #ifdef CONFIG_CGROUPS @@ -300,6 +301,9 @@ struct cgroup { /* used to schedule release agent */ struct work_struct release_agent_work; + /* used to store eBPF programs */ + struct cgroup_bpf bpf; + /* ids of the ancestors at each level including self */ int ancestor_ids[]; }; diff --git a/init/Kconfig b/init/Kconfig index 34407f1..405120b 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1154,6 +1154,18 @@ config CGROUP_PERF Say N if unsure. +config CGROUP_BPF + bool "Support for eBPF programs attached to cgroups" + depends on BPF_SYSCALL && SOCK_CGROUP_DATA + help + Allow attaching eBPF programs to a cgroup using the bpf(2) + syscall command BPF_PROG_ATTACH. + + In which context these programs are accessed depends on the type + of attachment. For instance, programs that are attached using + BPF_CGROUP_INET_INGRESS will be executed on the ingress path of + inet sockets. + config CGROUP_DEBUG bool "Example controller" default n diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile index c4d89d6..1276474 100644 --- a/kernel/bpf/Makefile +++ b/kernel/bpf/Makefile @@ -5,3 +5,4 @@ obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list ifeq ($(CONFIG_PERF_EVENTS),y) obj-$(CONFIG_BPF_SYSCALL) += stackmap.o endif +obj-$(CONFIG_CGROUP_BPF) += cgroup.o diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c new file mode 100644 index 0000000..a0ab43f --- /dev/null +++ b/kernel/bpf/cgroup.c @@ -0,0 +1,167 @@ +/* + * Functions to manage eBPF programs attached to cgroups + * + * Copyright (c) 2016 Daniel Mack + * + * This file is subject to the terms and conditions of version 2 of the GNU + * General Public License. See the file COPYING in the main directory of the + * Linux distribution for more details. + */ + +#include <linux/kernel.h> +#include <linux/atomic.h> +#include <linux/cgroup.h> +#include <linux/slab.h> +#include <linux/bpf.h> +#include <linux/bpf-cgroup.h> +#include <net/sock.h> + +DEFINE_STATIC_KEY_FALSE(cgroup_bpf_enabled_key); +EXPORT_SYMBOL(cgroup_bpf_enabled_key); + +/** + * cgroup_bpf_put() - put references of all bpf programs + * @cgrp: the cgroup to modify + */ +void cgroup_bpf_put(struct cgroup *cgrp) +{ + unsigned int type; + + for (type = 0; type < ARRAY_SIZE(cgrp->bpf.prog); type++) { + struct bpf_prog *prog = cgrp->bpf.prog[type]; + + if (prog) { + bpf_prog_put(prog); + static_branch_dec(&cgroup_bpf_enabled_key); + } + } +} + +/** + * cgroup_bpf_inherit() - inherit effective programs from parent + * @cgrp: the cgroup to modify + * @parent: the parent to inherit from + */ +void cgroup_bpf_inherit(struct cgroup *cgrp, struct cgroup *parent) +{ + unsigned int type; + + for (type = 0; type < ARRAY_SIZE(cgrp->bpf.effective); type++) { + struct bpf_prog *e; + + e = rcu_dereference_protected(parent->bpf.effective[type], + lockdep_is_held(&cgroup_mutex)); + rcu_assign_pointer(cgrp->bpf.effective[type], e); + } +} + +/** + * __cgroup_bpf_update() - Update the pinned program of a cgroup, and + * propagate the change to descendants + * @cgrp: The cgroup which descendants to traverse + * @parent: The parent of @cgrp, or %NULL if @cgrp is the root + * @prog: A new program to pin + * @type: Type of pinning operation (ingress/egress) + * + * Each cgroup has a set of two pointers for bpf programs; one for eBPF + * programs it owns, and which is effective for execution. + * + * If @prog is %NULL, this function attaches a new program to the cgroup and + * releases the one that is currently attached, if any. @prog is then made + * the effective program of type @type in that cgroup. + * + * If @prog is %NULL, the currently attached program of type @type is released, + * and the effective program of the parent cgroup (if any) is inherited to + * @cgrp. + * + * Then, the descendants of @cgrp are walked and the effective program for + * each of them is set to the effective program of @cgrp unless the + * descendant has its own program attached, in which case the subbranch is + * skipped. This ensures that delegated subcgroups with own programs are left + * untouched. + * + * Must be called with cgroup_mutex held. + */ +void __cgroup_bpf_update(struct cgroup *cgrp, + struct cgroup *parent, + struct bpf_prog *prog, + enum bpf_attach_type type) +{ + struct bpf_prog *old_prog, *effective; + struct cgroup_subsys_state *pos; + + old_prog = xchg(cgrp->bpf.prog + type, prog); + + effective = (!prog && parent) ? + rcu_dereference_protected(parent->bpf.effective[type], + lockdep_is_held(&cgroup_mutex)) : + prog; + + css_for_each_descendant_pre(pos, &cgrp->self) { + struct cgroup *desc = container_of(pos, struct cgroup, self); + + /* skip the subtree if the descendant has its own program */ + if (desc->bpf.prog[type] && desc != cgrp) + pos = css_rightmost_descendant(pos); + else + rcu_assign_pointer(desc->bpf.effective[type], + effective); + } + + if (prog) + static_branch_inc(&cgroup_bpf_enabled_key); + + if (old_prog) { + bpf_prog_put(old_prog); + static_branch_dec(&cgroup_bpf_enabled_key); + } +} + +/** + * __cgroup_bpf_run_filter() - Run a program for packet filtering + * @sk: The socken sending or receiving traffic + * @skb: The skb that is being sent or received + * @type: The type of program to be exectuted + * + * If no socket is passed, or the socket is not of type INET or INET6, + * this function does nothing and returns 0. + * + * The program type passed in via @type must be suitable for network + * 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(struct sock *sk, + struct sk_buff *skb, + enum bpf_attach_type type) +{ + struct bpf_prog *prog; + struct cgroup *cgrp; + int ret = 0; + + if (!sk || !sk_fullsock(sk)) + return 0; + + if (sk->sk_family != AF_INET && + sk->sk_family != AF_INET6) + return 0; + + cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data); + + rcu_read_lock(); + + prog = rcu_dereference(cgrp->bpf.effective[type]); + if (prog) { + unsigned int offset = skb->data - skb_network_header(skb); + + __skb_push(skb, offset); + ret = bpf_prog_run_save_cb(prog, skb) == 1 ? 0 : -EPERM; + __skb_pull(skb, offset); + } + + rcu_read_unlock(); + + return ret; +} +EXPORT_SYMBOL(__cgroup_bpf_run_filter); diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 85bc9be..2ee9ec3 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -5074,6 +5074,8 @@ static void css_release_work_fn(struct work_struct *work) if (cgrp->kn) RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL); + + cgroup_bpf_put(cgrp); } mutex_unlock(&cgroup_mutex); @@ -5281,6 +5283,9 @@ static struct cgroup *cgroup_create(struct cgroup *parent) if (!cgroup_on_dfl(cgrp)) cgrp->subtree_control = cgroup_control(cgrp); + if (parent) + cgroup_bpf_inherit(cgrp, parent); + cgroup_propagate_control(cgrp); /* @cgrp doesn't have dir yet so the following will only create csses */ @@ -6495,6 +6500,19 @@ static __init int cgroup_namespaces_init(void) } subsys_initcall(cgroup_namespaces_init); +#ifdef CONFIG_CGROUP_BPF +void cgroup_bpf_update(struct cgroup *cgrp, + struct bpf_prog *prog, + enum bpf_attach_type type) +{ + struct cgroup *parent = cgroup_parent(cgrp); + + mutex_lock(&cgroup_mutex); + __cgroup_bpf_update(cgrp, parent, prog, type); + mutex_unlock(&cgroup_mutex); +} +#endif /* CONFIG_CGROUP_BPF */ + #ifdef CONFIG_CGROUP_DEBUG static struct cgroup_subsys_state * debug_css_alloc(struct cgroup_subsys_state *parent_css) |
