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linux-stable/include/linux/bpf-cgroup.h
Andrii Nakryiko af6eea5743 bpf: Implement bpf_link-based cgroup BPF program attachment 
Implement new sub-command to attach cgroup BPF programs and return FD-based
bpf_link back on success. bpf_link, once attached to cgroup, cannot be
replaced, except by owner having its FD. Cgroup bpf_link supports only
BPF_F_ALLOW_MULTI semantics. Both link-based and prog-based BPF_F_ALLOW_MULTI
attachments can be freely intermixed.

To prevent bpf_cgroup_link from keeping cgroup alive past the point when no
BPF program can be executed, implement auto-detachment of link. When
cgroup_bpf_release() is called, all attached bpf_links are forced to release
cgroup refcounts, but they leave bpf_link otherwise active and allocated, as
well as still owning underlying bpf_prog. This is because user-space might
still have FDs open and active, so bpf_link as a user-referenced object can't
be freed yet. Once last active FD is closed, bpf_link will be freed and
underlying bpf_prog refcount will be dropped. But cgroup refcount won't be
touched, because cgroup is released already.

The inherent race between bpf_cgroup_link release (from closing last FD) and
cgroup_bpf_release() is resolved by both operations taking cgroup_mutex. So
the only additional check required is when bpf_cgroup_link attempts to detach
itself from cgroup. At that time we need to check whether there is still
cgroup associated with that link. And if not, exit with success, because
bpf_cgroup_link was already successfully detached.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Roman Gushchin <guro@fb.com>
Link: https://lore.kernel.org/bpf/20200330030001.2312810-2-andriin@fb.com
2020-03-30 17:35:59 -07:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BPF_CGROUP_H
#define _BPF_CGROUP_H
#include <linux/bpf.h>
#include <linux/errno.h>
#include <linux/jump_label.h>
#include <linux/percpu.h>
#include <linux/percpu-refcount.h>
#include <linux/rbtree.h>
#include <uapi/linux/bpf.h>
struct sock;
struct sockaddr;
struct cgroup;
struct sk_buff;
struct bpf_map;
struct bpf_prog;
struct bpf_sock_ops_kern;
struct bpf_cgroup_storage;
struct ctl_table;
struct ctl_table_header;
#ifdef CONFIG_CGROUP_BPF
extern struct static_key_false cgroup_bpf_enabled_key;
#define cgroup_bpf_enabled static_branch_unlikely(&cgroup_bpf_enabled_key)
DECLARE_PER_CPU(struct bpf_cgroup_storage*,
bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
#define for_each_cgroup_storage_type(stype) \
for (stype = 0; stype < MAX_BPF_CGROUP_STORAGE_TYPE; stype++)
struct bpf_cgroup_storage_map;
struct bpf_storage_buffer {
struct rcu_head rcu;
char data[];
};
struct bpf_cgroup_storage {
union {
struct bpf_storage_buffer *buf;
void __percpu *percpu_buf;
};
struct bpf_cgroup_storage_map *map;
struct bpf_cgroup_storage_key key;
struct list_head list;
struct rb_node node;
struct rcu_head rcu;
};
struct bpf_cgroup_link {
struct bpf_link link;
struct cgroup *cgroup;
enum bpf_attach_type type;
};
extern const struct bpf_link_ops bpf_cgroup_link_lops;
struct bpf_prog_list {
struct list_head node;
struct bpf_prog *prog;
struct bpf_cgroup_link *link;
struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE];
};
struct bpf_prog_array;
struct cgroup_bpf {
/* array of effective progs in this cgroup */
struct bpf_prog_array __rcu *effective[MAX_BPF_ATTACH_TYPE];
/* attached progs to this cgroup and attach flags
* when flags == 0 or BPF_F_ALLOW_OVERRIDE the progs list will
* have either zero or one element
* when BPF_F_ALLOW_MULTI the list can have up to BPF_CGROUP_MAX_PROGS
*/
struct list_head progs[MAX_BPF_ATTACH_TYPE];
u32 flags[MAX_BPF_ATTACH_TYPE];
/* temp storage for effective prog array used by prog_attach/detach */
struct bpf_prog_array *inactive;
/* reference counter used to detach bpf programs after cgroup removal */
struct percpu_ref refcnt;
/* cgroup_bpf is released using a work queue */
struct work_struct release_work;
};
int cgroup_bpf_inherit(struct cgroup *cgrp);
void cgroup_bpf_offline(struct cgroup *cgrp);
int __cgroup_bpf_attach(struct cgroup *cgrp,
struct bpf_prog *prog, struct bpf_prog *replace_prog,
struct bpf_cgroup_link *link,
enum bpf_attach_type type, u32 flags);
int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
struct bpf_cgroup_link *link,
enum bpf_attach_type type);
int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
union bpf_attr __user *uattr);
/* Wrapper for __cgroup_bpf_*() protected by cgroup_mutex */
int cgroup_bpf_attach(struct cgroup *cgrp,
struct bpf_prog *prog, struct bpf_prog *replace_prog,
struct bpf_cgroup_link *link, enum bpf_attach_type type,
u32 flags);
int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
enum bpf_attach_type type);
int cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
union bpf_attr __user *uattr);
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);
int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
struct sockaddr *uaddr,
enum bpf_attach_type type,
void *t_ctx);
int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
struct bpf_sock_ops_kern *sock_ops,
enum bpf_attach_type type);
int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
short access, enum bpf_attach_type type);
int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
struct ctl_table *table, int write,
void __user *buf, size_t *pcount,
loff_t *ppos, void **new_buf,
enum bpf_attach_type type);
int __cgroup_bpf_run_filter_setsockopt(struct sock *sock, int *level,
int *optname, char __user *optval,
int *optlen, char **kernel_optval);
int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
int optname, char __user *optval,
int __user *optlen, int max_optlen,
int retval);
static inline enum bpf_cgroup_storage_type cgroup_storage_type(
struct bpf_map *map)
{
if (map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
return BPF_CGROUP_STORAGE_PERCPU;
return BPF_CGROUP_STORAGE_SHARED;
}
static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage
*storage[MAX_BPF_CGROUP_STORAGE_TYPE])
{
enum bpf_cgroup_storage_type stype;
for_each_cgroup_storage_type(stype)
this_cpu_write(bpf_cgroup_storage[stype], storage[stype]);
}
struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
enum bpf_cgroup_storage_type stype);
void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage);
void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
struct cgroup *cgroup,
enum bpf_attach_type type);
void bpf_cgroup_storage_unlink(struct bpf_cgroup_storage *storage);
int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux, struct bpf_map *map);
void bpf_cgroup_storage_release(struct bpf_prog_aux *aux, struct bpf_map *map);
int bpf_percpu_cgroup_storage_copy(struct bpf_map *map, void *key, void *value);
int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key,
void *value, u64 flags);
/* Wrappers for __cgroup_bpf_run_filter_skb() 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_skb(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_skb(__sk, skb, \
BPF_CGROUP_INET_EGRESS); \
} \
__ret; \
})
#define BPF_CGROUP_RUN_SK_PROG(sk, type) \
({ \
int __ret = 0; \
if (cgroup_bpf_enabled) { \
__ret = __cgroup_bpf_run_filter_sk(sk, type); \
} \
__ret; \
})
#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) \
BPF_CGROUP_RUN_SK_PROG(sk, BPF_CGROUP_INET_SOCK_CREATE)
#define BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk) \
BPF_CGROUP_RUN_SK_PROG(sk, BPF_CGROUP_INET4_POST_BIND)
#define BPF_CGROUP_RUN_PROG_INET6_POST_BIND(sk) \
BPF_CGROUP_RUN_SK_PROG(sk, BPF_CGROUP_INET6_POST_BIND)
#define BPF_CGROUP_RUN_SA_PROG(sk, uaddr, type) \
({ \
int __ret = 0; \
if (cgroup_bpf_enabled) \
__ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type, \
NULL); \
__ret; \
})
#define BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, type, t_ctx) \
({ \
int __ret = 0; \
if (cgroup_bpf_enabled) { \
lock_sock(sk); \
__ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type, \
t_ctx); \
release_sock(sk); \
} \
__ret; \
})
#define BPF_CGROUP_RUN_PROG_INET4_BIND(sk, uaddr) \
BPF_CGROUP_RUN_SA_PROG(sk, uaddr, BPF_CGROUP_INET4_BIND)
#define BPF_CGROUP_RUN_PROG_INET6_BIND(sk, uaddr) \
BPF_CGROUP_RUN_SA_PROG(sk, uaddr, BPF_CGROUP_INET6_BIND)
#define BPF_CGROUP_PRE_CONNECT_ENABLED(sk) (cgroup_bpf_enabled && \
sk->sk_prot->pre_connect)
#define BPF_CGROUP_RUN_PROG_INET4_CONNECT(sk, uaddr) \
BPF_CGROUP_RUN_SA_PROG(sk, uaddr, BPF_CGROUP_INET4_CONNECT)
#define BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr) \
BPF_CGROUP_RUN_SA_PROG(sk, uaddr, BPF_CGROUP_INET6_CONNECT)
#define BPF_CGROUP_RUN_PROG_INET4_CONNECT_LOCK(sk, uaddr) \
BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_INET4_CONNECT, NULL)
#define BPF_CGROUP_RUN_PROG_INET6_CONNECT_LOCK(sk, uaddr) \
BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_INET6_CONNECT, NULL)
#define BPF_CGROUP_RUN_PROG_UDP4_SENDMSG_LOCK(sk, uaddr, t_ctx) \
BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_UDP4_SENDMSG, t_ctx)
#define BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk, uaddr, t_ctx) \
BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_UDP6_SENDMSG, t_ctx)
#define BPF_CGROUP_RUN_PROG_UDP4_RECVMSG_LOCK(sk, uaddr) \
BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_UDP4_RECVMSG, NULL)
#define BPF_CGROUP_RUN_PROG_UDP6_RECVMSG_LOCK(sk, uaddr) \
BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_UDP6_RECVMSG, NULL)
#define BPF_CGROUP_RUN_PROG_SOCK_OPS(sock_ops) \
({ \
int __ret = 0; \
if (cgroup_bpf_enabled && (sock_ops)->sk) { \
typeof(sk) __sk = sk_to_full_sk((sock_ops)->sk); \
if (__sk && sk_fullsock(__sk)) \
__ret = __cgroup_bpf_run_filter_sock_ops(__sk, \
sock_ops, \
BPF_CGROUP_SOCK_OPS); \
} \
__ret; \
})
#define BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type, major, minor, access) \
({ \
int __ret = 0; \
if (cgroup_bpf_enabled) \
__ret = __cgroup_bpf_check_dev_permission(type, major, minor, \
access, \
BPF_CGROUP_DEVICE); \
\
__ret; \
})
#define BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, buf, count, pos, nbuf) \
({ \
int __ret = 0; \
if (cgroup_bpf_enabled) \
__ret = __cgroup_bpf_run_filter_sysctl(head, table, write, \
buf, count, pos, nbuf, \
BPF_CGROUP_SYSCTL); \
__ret; \
})
#define BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock, level, optname, optval, optlen, \
kernel_optval) \
({ \
int __ret = 0; \
if (cgroup_bpf_enabled) \
__ret = __cgroup_bpf_run_filter_setsockopt(sock, level, \
optname, optval, \
optlen, \
kernel_optval); \
__ret; \
})
#define BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen) \
({ \
int __ret = 0; \
if (cgroup_bpf_enabled) \
get_user(__ret, optlen); \
__ret; \
})
#define BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock, level, optname, optval, optlen, \
max_optlen, retval) \
({ \
int __ret = retval; \
if (cgroup_bpf_enabled) \
__ret = __cgroup_bpf_run_filter_getsockopt(sock, level, \
optname, optval, \
optlen, max_optlen, \
retval); \
__ret; \
})
int cgroup_bpf_prog_attach(const union bpf_attr *attr,
enum bpf_prog_type ptype, struct bpf_prog *prog);
int cgroup_bpf_prog_detach(const union bpf_attr *attr,
enum bpf_prog_type ptype);
int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
int cgroup_bpf_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr);
#else
struct bpf_prog;
struct cgroup_bpf {};
static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; }
static inline void cgroup_bpf_offline(struct cgroup *cgrp) {}
static inline int cgroup_bpf_prog_attach(const union bpf_attr *attr,
enum bpf_prog_type ptype,
struct bpf_prog *prog)
{
return -EINVAL;
}
static inline int cgroup_bpf_prog_detach(const union bpf_attr *attr,
enum bpf_prog_type ptype)
{
return -EINVAL;
}
static inline int cgroup_bpf_link_attach(const union bpf_attr *attr,
struct bpf_prog *prog)
{
return -EINVAL;
}
static inline int cgroup_bpf_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
return -EINVAL;
}
static inline void bpf_cgroup_storage_set(
struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE]) {}
static inline int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux,
struct bpf_map *map) { return 0; }
static inline void bpf_cgroup_storage_release(struct bpf_prog_aux *aux,
struct bpf_map *map) {}
static inline struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(
struct bpf_prog *prog, enum bpf_cgroup_storage_type stype) { return NULL; }
static inline void bpf_cgroup_storage_free(
struct bpf_cgroup_storage *storage) {}
static inline int bpf_percpu_cgroup_storage_copy(struct bpf_map *map, void *key,
void *value) {
return 0;
}
static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map,
void *key, void *value, u64 flags) {
return 0;
}
#define cgroup_bpf_enabled (0)
#define BPF_CGROUP_PRE_CONNECT_ENABLED(sk) (0)
#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; })
#define BPF_CGROUP_RUN_PROG_INET4_BIND(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET6_BIND(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET6_POST_BIND(sk) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET4_CONNECT(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET4_CONNECT_LOCK(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET6_CONNECT_LOCK(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_UDP4_SENDMSG_LOCK(sk, uaddr, t_ctx) ({ 0; })
#define BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk, uaddr, t_ctx) ({ 0; })
#define BPF_CGROUP_RUN_PROG_UDP4_RECVMSG_LOCK(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_UDP6_RECVMSG_LOCK(sk, uaddr) ({ 0; })
#define BPF_CGROUP_RUN_PROG_SOCK_OPS(sock_ops) ({ 0; })
#define BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type,major,minor,access) ({ 0; })
#define BPF_CGROUP_RUN_PROG_SYSCTL(head,table,write,buf,count,pos,nbuf) ({ 0; })
#define BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen) ({ 0; })
#define BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock, level, optname, optval, \
optlen, max_optlen, retval) ({ retval; })
#define BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock, level, optname, optval, optlen, \
kernel_optval) ({ 0; })
#define for_each_cgroup_storage_type(stype) for (; false; )
#endif /* CONFIG_CGROUP_BPF */
#endif /* _BPF_CGROUP_H */
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