From cae1927c0b4a93ae15de824faca1f6f611a44fcd Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Wed, 27 Dec 2017 18:39:05 -0800 Subject: [PATCH] bpf: offload: allow netdev to disappear while verifier is running To allow verifier instruction callbacks without any extra locking NETDEV_UNREGISTER notification would wait on a waitqueue for verifier to finish. This design decision was made when rtnl lock was providing all the locking. Use the read/write lock instead and remove the workqueue. Verifier will now call into the offload code, so dev_ops are moved to offload structure. Since verifier calls are all under bpf_prog_is_dev_bound() we no longer need static inline implementations to please builds with CONFIG_NET=n. Signed-off-by: Jakub Kicinski Reviewed-by: Quentin Monnet Acked-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- drivers/net/ethernet/netronome/nfp/bpf/main.h | 2 +- .../net/ethernet/netronome/nfp/bpf/verifier.c | 2 +- drivers/net/netdevsim/bpf.c | 2 +- include/linux/bpf.h | 9 ++++-- include/linux/bpf_verifier.h | 16 ++-------- include/linux/netdevice.h | 4 +-- kernel/bpf/offload.c | 30 ++++++++++--------- kernel/bpf/verifier.c | 20 +++++-------- 8 files changed, 37 insertions(+), 48 deletions(-) diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h index aae1be9ed056..89a9b6393882 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/main.h +++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h @@ -238,7 +238,7 @@ struct nfp_bpf_vnic { int nfp_bpf_jit(struct nfp_prog *prog); -extern const struct bpf_ext_analyzer_ops nfp_bpf_analyzer_ops; +extern const struct bpf_prog_offload_ops nfp_bpf_analyzer_ops; struct netdev_bpf; struct nfp_app; diff --git a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c index 9c2608445bd8..d8870c2f11f3 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c +++ b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c @@ -260,6 +260,6 @@ nfp_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx) return 0; } -const struct bpf_ext_analyzer_ops nfp_bpf_analyzer_ops = { +const struct bpf_prog_offload_ops nfp_bpf_analyzer_ops = { .insn_hook = nfp_verify_insn, }; diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c index a243fa7ae02f..5134d5c1306c 100644 --- a/drivers/net/netdevsim/bpf.c +++ b/drivers/net/netdevsim/bpf.c @@ -66,7 +66,7 @@ nsim_bpf_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn) return 0; } -static const struct bpf_ext_analyzer_ops nsim_bpf_analyzer_ops = { +static const struct bpf_prog_offload_ops nsim_bpf_analyzer_ops = { .insn_hook = nsim_bpf_verify_insn, }; diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 838eee10e979..669549f7e3e8 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -17,6 +17,7 @@ #include #include +struct bpf_verifier_env; struct perf_event; struct bpf_prog; struct bpf_map; @@ -184,14 +185,18 @@ struct bpf_verifier_ops { struct bpf_prog *prog, u32 *target_size); }; +struct bpf_prog_offload_ops { + int (*insn_hook)(struct bpf_verifier_env *env, + int insn_idx, int prev_insn_idx); +}; + struct bpf_dev_offload { struct bpf_prog *prog; struct net_device *netdev; void *dev_priv; struct list_head offloads; bool dev_state; - bool verifier_running; - wait_queue_head_t verifier_done; + const struct bpf_prog_offload_ops *dev_ops; }; struct bpf_prog_aux { diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 883a35d50cd5..2feb218c001d 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -166,12 +166,6 @@ static inline bool bpf_verifier_log_full(const struct bpf_verifer_log *log) return log->len_used >= log->len_total - 1; } -struct bpf_verifier_env; -struct bpf_ext_analyzer_ops { - int (*insn_hook)(struct bpf_verifier_env *env, - int insn_idx, int prev_insn_idx); -}; - #define BPF_MAX_SUBPROGS 256 /* single container for all structs @@ -185,7 +179,6 @@ struct bpf_verifier_env { bool strict_alignment; /* perform strict pointer alignment checks */ struct bpf_verifier_state *cur_state; /* current verifier state */ struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ - const struct bpf_ext_analyzer_ops *dev_ops; /* device analyzer ops */ struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ u32 used_map_cnt; /* number of used maps */ u32 id_gen; /* used to generate unique reg IDs */ @@ -206,13 +199,8 @@ static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env) return cur->frame[cur->curframe]->regs; } -#if defined(CONFIG_NET) && defined(CONFIG_BPF_SYSCALL) int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env); -#else -static inline int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env) -{ - return -EOPNOTSUPP; -} -#endif +int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env, + int insn_idx, int prev_insn_idx); #endif /* _LINUX_BPF_VERIFIER_H */ diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 352066e4eeef..49bfc6eec74c 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -804,7 +804,7 @@ enum bpf_netdev_command { BPF_OFFLOAD_DESTROY, }; -struct bpf_ext_analyzer_ops; +struct bpf_prog_offload_ops; struct netlink_ext_ack; struct netdev_bpf { @@ -826,7 +826,7 @@ struct netdev_bpf { /* BPF_OFFLOAD_VERIFIER_PREP */ struct { struct bpf_prog *prog; - const struct bpf_ext_analyzer_ops *ops; /* callee set */ + const struct bpf_prog_offload_ops *ops; /* callee set */ } verifier; /* BPF_OFFLOAD_TRANSLATE, BPF_OFFLOAD_DESTROY */ struct { diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c index 032079754d88..69ddc3899bab 100644 --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -44,7 +44,6 @@ int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr) return -ENOMEM; offload->prog = prog; - init_waitqueue_head(&offload->verifier_done); offload->netdev = dev_get_by_index(current->nsproxy->net_ns, attr->prog_ifindex); @@ -97,15 +96,28 @@ int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env) if (err) goto exit_unlock; - env->dev_ops = data.verifier.ops; - + env->prog->aux->offload->dev_ops = data.verifier.ops; env->prog->aux->offload->dev_state = true; - env->prog->aux->offload->verifier_running = true; exit_unlock: rtnl_unlock(); return err; } +int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env, + int insn_idx, int prev_insn_idx) +{ + struct bpf_dev_offload *offload; + int ret = -ENODEV; + + down_read(&bpf_devs_lock); + offload = env->prog->aux->offload; + if (offload->netdev) + ret = offload->dev_ops->insn_hook(env, insn_idx, prev_insn_idx); + up_read(&bpf_devs_lock); + + return ret; +} + static void __bpf_prog_offload_destroy(struct bpf_prog *prog) { struct bpf_dev_offload *offload = prog->aux->offload; @@ -117,9 +129,6 @@ static void __bpf_prog_offload_destroy(struct bpf_prog *prog) data.offload.prog = prog; - if (offload->verifier_running) - wait_event(offload->verifier_done, !offload->verifier_running); - if (offload->dev_state) WARN_ON(__bpf_offload_ndo(prog, BPF_OFFLOAD_DESTROY, &data)); @@ -132,9 +141,6 @@ void bpf_prog_offload_destroy(struct bpf_prog *prog) { struct bpf_dev_offload *offload = prog->aux->offload; - offload->verifier_running = false; - wake_up(&offload->verifier_done); - rtnl_lock(); down_write(&bpf_devs_lock); __bpf_prog_offload_destroy(prog); @@ -146,15 +152,11 @@ void bpf_prog_offload_destroy(struct bpf_prog *prog) static int bpf_prog_offload_translate(struct bpf_prog *prog) { - struct bpf_dev_offload *offload = prog->aux->offload; struct netdev_bpf data = {}; int ret; data.offload.prog = prog; - offload->verifier_running = false; - wake_up(&offload->verifier_done); - rtnl_lock(); ret = __bpf_offload_ndo(prog, BPF_OFFLOAD_TRANSLATE, &data); rtnl_unlock(); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 98d8637cf70d..a2b211262c25 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4438,15 +4438,6 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) return 0; } -static int ext_analyzer_insn_hook(struct bpf_verifier_env *env, - int insn_idx, int prev_insn_idx) -{ - if (env->dev_ops && env->dev_ops->insn_hook) - return env->dev_ops->insn_hook(env, insn_idx, prev_insn_idx); - - return 0; -} - static int do_check(struct bpf_verifier_env *env) { struct bpf_verifier_state *state; @@ -4531,9 +4522,12 @@ static int do_check(struct bpf_verifier_env *env) print_bpf_insn(&cbs, env, insn, env->allow_ptr_leaks); } - err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx); - if (err) - return err; + if (bpf_prog_is_dev_bound(env->prog->aux)) { + err = bpf_prog_offload_verify_insn(env, insn_idx, + prev_insn_idx); + if (err) + return err; + } regs = cur_regs(env); env->insn_aux_data[insn_idx].seen = true; @@ -5463,7 +5457,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) env->strict_alignment = true; - if (env->prog->aux->offload) { + if (bpf_prog_is_dev_bound(env->prog->aux)) { ret = bpf_prog_offload_verifier_prep(env); if (ret) goto err_unlock; -- 2.34.1