[RFCv2,07/16] bpf: enable non-core use of the verfier

Message ID	1472234775-29453-8-git-send-email-jakub.kicinski@netronome.com
State	RFC, archived
Delegated to:	David Miller
Headers	show Return-Path: <netdev-owner@vger.kernel.org> From: Jakub Kicinski <jakub.kicinski@netronome.com> To: netdev@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, dinan.gunawardena@netronome.com, jiri@resnulli.us, john.fastabend@gmail.com, kubakici@wp.pl, Jakub Kicinski <jakub.kicinski@netronome.com> Subject: [RFCv2 07/16] bpf: enable non-core use of the verfier Date: Fri, 26 Aug 2016 19:06:06 +0100 Message-Id: <1472234775-29453-8-git-send-email-jakub.kicinski@netronome.com> In-Reply-To: <1472234775-29453-1-git-send-email-jakub.kicinski@netronome.com> References: <1472234775-29453-1-git-send-email-jakub.kicinski@netronome.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk

diff --git a/include/linux/bpf_parser.h b/include/linux/bpf_parser.h new file mode 100644 index 000000000000..1b73cc464914 --- /dev/null +++ b/include/linux/bpf_parser.h @@ -0,0 +1,84 @@ +/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ +#ifndef _LINUX_BPF_PARSER_H +#define _LINUX_BPF_PARSER_H 1 + +#include <linux/bpf.h> /* for enum bpf_reg_type */ +#include <linux/filter.h> /* for MAX_BPF_STACK */ + +struct reg_state { + enum bpf_reg_type type; + union { + /* valid when type == CONST_IMM | PTR_TO_STACK | UNKNOWN_VALUE */ + s64 imm; + + /* valid when type == PTR_TO_PACKET* */ + struct { + u32 id; + u16 off; + u16 range; + }; + + /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | + * PTR_TO_MAP_VALUE_OR_NULL + */ + struct bpf_map *map_ptr; + }; +}; + +enum bpf_stack_slot_type { + STACK_INVALID, /* nothing was stored in this stack slot */ + STACK_SPILL, /* register spilled into stack */ + STACK_MISC /* BPF program wrote some data into this slot */ +}; + +#define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ + +/* state of the program: + * type of all registers and stack info + */ +struct verifier_state { + struct reg_state regs[MAX_BPF_REG]; + u8 stack_slot_type[MAX_BPF_STACK]; + struct reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE]; +}; + +/* linked list of verifier states used to prune search */ +struct verifier_state_list { + struct verifier_state state; + struct verifier_state_list *next; +}; + +#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ + +struct verifier_env; +struct bpf_ext_parser_ops { + int (*insn_hook)(struct verifier_env *env, + int insn_idx, int prev_insn_idx); +}; + +/* single container for all structs + * one verifier_env per bpf_check() call + */ +struct verifier_env { + struct bpf_prog *prog; /* eBPF program being verified */ + struct verifier_stack_elem *head; /* stack of verifier states to be processed */ + int stack_size; /* number of states to be processed */ + struct verifier_state cur_state; /* current verifier state */ + struct verifier_state_list **explored_states; /* search pruning optimization */ + const struct bpf_ext_parser_ops *pops; /* external parser ops */ + void *ppriv; /* pointer to external parser's private data */ + 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 */ + bool allow_ptr_leaks; +}; + +int bpf_parse(struct bpf_prog *prog, const struct bpf_ext_parser_ops *pops, + void *ppriv); + +#endif /* _LINUX_BPF_PARSER_H */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 0f4494c194f9..e91faad7d2b2 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14,6 +14,7 @@ #include <linux/types.h> #include <linux/slab.h> #include <linux/bpf.h> +#include <linux/bpf_parser.h> #include <linux/filter.h> #include <net/netlink.h> #include <linux/file.h> @@ -126,49 +127,6 @@ * are set to NOT_INIT to indicate that they are no longer readable. */ -struct reg_state { - enum bpf_reg_type type; - union { - /* valid when type == CONST_IMM | PTR_TO_STACK | UNKNOWN_VALUE */ - s64 imm; - - /* valid when type == PTR_TO_PACKET* */ - struct { - u32 id; - u16 off; - u16 range; - }; - - /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | - * PTR_TO_MAP_VALUE_OR_NULL - */ - struct bpf_map *map_ptr; - }; -}; - -enum bpf_stack_slot_type { - STACK_INVALID, /* nothing was stored in this stack slot */ - STACK_SPILL, /* register spilled into stack */ - STACK_MISC /* BPF program wrote some data into this slot */ -}; - -#define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ - -/* state of the program: - * type of all registers and stack info - */ -struct verifier_state { - struct reg_state regs[MAX_BPF_REG]; - u8 stack_slot_type[MAX_BPF_STACK]; - struct reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE]; -}; - -/* linked list of verifier states used to prune search */ -struct verifier_state_list { - struct verifier_state state; - struct verifier_state_list *next; -}; - /* verifier_state + insn_idx are pushed to stack when branch is encountered */ struct verifier_stack_elem { /* verifer state is 'st' @@ -181,23 +139,6 @@ struct verifier_stack_elem { struct verifier_stack_elem *next; }; -#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ - -/* single container for all structs - * one verifier_env per bpf_check() call - */ -struct verifier_env { - struct bpf_prog *prog; /* eBPF program being verified */ - struct verifier_stack_elem *head; /* stack of verifier states to be processed */ - int stack_size; /* number of states to be processed */ - struct verifier_state cur_state; /* current verifier state */ - struct verifier_state_list **explored_states; /* search pruning optimization */ - 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 */ - bool allow_ptr_leaks; -}; - #define BPF_COMPLEXITY_LIMIT_INSNS 65536 #define BPF_COMPLEXITY_LIMIT_STACK 1024 @@ -683,6 +624,10 @@ static int check_packet_access(struct verifier_env *env, u32 regno, int off, static int check_ctx_access(struct verifier_env *env, int off, int size, enum bpf_access_type t, enum bpf_reg_type *reg_type) { + /* for parser ctx accesses are already validated and converted */ + if (env->pops) + return 0; + if (env->prog->aux->ops->is_valid_access && env->prog->aux->ops->is_valid_access(off, size, t, reg_type)) { /* remember the offset of last byte accessed in ctx */ @@ -2256,6 +2201,15 @@ static int is_state_visited(struct verifier_env *env, int insn_idx) return 0; } +static int ext_parser_hook(struct verifier_env *env, + int insn_idx, int prev_insn_idx) +{ + if (!env->pops || !env->pops->insn_hook) + return 0; + + return env->pops->insn_hook(env, insn_idx, prev_insn_idx); +} + static int do_check(struct verifier_env *env) { struct verifier_state *state = &env->cur_state; @@ -2314,6 +2268,10 @@ static int do_check(struct verifier_env *env) print_bpf_insn(insn); } + err = ext_parser_hook(env, insn_idx, prev_insn_idx); + if (err) + return err; + if (class == BPF_ALU || class == BPF_ALU64) { err = check_alu_op(env, insn); if (err) @@ -2832,3 +2790,47 @@ free_env: mutex_unlock(&bpf_verifier_lock); return ret; } + +int bpf_parse(struct bpf_prog *prog, const struct bpf_ext_parser_ops *pops, + void *ppriv) +{ + struct verifier_env *env; + int ret; + + env = kzalloc(sizeof(struct verifier_env), GFP_KERNEL); + if (!env) + return -ENOMEM; + + env->prog = prog; + env->pops = pops; + env->ppriv = ppriv; + + /* grab the mutex to protect few globals used by verifier */ + mutex_lock(&bpf_verifier_lock); + + log_level = 0; + + env->explored_states = kcalloc(env->prog->len, + sizeof(struct verifier_state_list *), + GFP_KERNEL); + ret = -ENOMEM; + if (!env->explored_states) + goto skip_full_check; + + ret = check_cfg(env); + if (ret < 0) + goto skip_full_check; + + env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); + + ret = do_check(env); + +skip_full_check: + while (pop_stack(env, NULL) >= 0); + free_states(env); + + kfree(env); + mutex_unlock(&bpf_verifier_lock); + return ret; +} +EXPORT_SYMBOL_GPL(bpf_parse);

[RFCv2,07/16] bpf: enable non-core use of the verfier

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