181 lines
6.2 KiB
C
181 lines
6.2 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#ifndef _LINUX_BPF_VERIFIER_H
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#define _LINUX_BPF_VERIFIER_H 1
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#include <linux/bpf.h> /* for enum bpf_reg_type */
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#include <linux/filter.h> /* for MAX_BPF_STACK */
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#include <linux/tnum.h>
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/* Maximum variable offset umax_value permitted when resolving memory accesses.
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* In practice this is far bigger than any realistic pointer offset; this limit
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* ensures that umax_value + (int)off + (int)size cannot overflow a u64.
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*/
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#define BPF_MAX_VAR_OFF (1ULL << 31)
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/* Maximum variable size permitted for ARG_CONST_SIZE[_OR_ZERO]. This ensures
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* that converting umax_value to int cannot overflow.
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*/
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#define BPF_MAX_VAR_SIZ INT_MAX
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/* Liveness marks, used for registers and spilled-regs (in stack slots).
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* Read marks propagate upwards until they find a write mark; they record that
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* "one of this state's descendants read this reg" (and therefore the reg is
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* relevant for states_equal() checks).
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* Write marks collect downwards and do not propagate; they record that "the
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* straight-line code that reached this state (from its parent) wrote this reg"
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* (and therefore that reads propagated from this state or its descendants
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* should not propagate to its parent).
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* A state with a write mark can receive read marks; it just won't propagate
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* them to its parent, since the write mark is a property, not of the state,
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* but of the link between it and its parent. See mark_reg_read() and
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* mark_stack_slot_read() in kernel/bpf/verifier.c.
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*/
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enum bpf_reg_liveness {
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REG_LIVE_NONE = 0, /* reg hasn't been read or written this branch */
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REG_LIVE_READ, /* reg was read, so we're sensitive to initial value */
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REG_LIVE_WRITTEN, /* reg was written first, screening off later reads */
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};
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struct bpf_reg_state {
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enum bpf_reg_type type;
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union {
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/* valid when type == PTR_TO_PACKET */
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u16 range;
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/* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |
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* PTR_TO_MAP_VALUE_OR_NULL
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*/
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struct bpf_map *map_ptr;
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};
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/* Fixed part of pointer offset, pointer types only */
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s32 off;
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/* For PTR_TO_PACKET, used to find other pointers with the same variable
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* offset, so they can share range knowledge.
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* For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we
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* came from, when one is tested for != NULL.
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*/
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u32 id;
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/* Ordering of fields matters. See states_equal() */
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/* For scalar types (SCALAR_VALUE), this represents our knowledge of
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* the actual value.
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* For pointer types, this represents the variable part of the offset
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* from the pointed-to object, and is shared with all bpf_reg_states
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* with the same id as us.
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*/
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struct tnum var_off;
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/* Used to determine if any memory access using this register will
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* result in a bad access.
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* These refer to the same value as var_off, not necessarily the actual
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* contents of the register.
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*/
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s64 smin_value; /* minimum possible (s64)value */
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s64 smax_value; /* maximum possible (s64)value */
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u64 umin_value; /* minimum possible (u64)value */
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u64 umax_value; /* maximum possible (u64)value */
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/* This field must be last, for states_equal() reasons. */
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enum bpf_reg_liveness live;
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};
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enum bpf_stack_slot_type {
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STACK_INVALID, /* nothing was stored in this stack slot */
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STACK_SPILL, /* register spilled into stack */
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STACK_MISC /* BPF program wrote some data into this slot */
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};
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#define BPF_REG_SIZE 8 /* size of eBPF register in bytes */
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struct bpf_stack_state {
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struct bpf_reg_state spilled_ptr;
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u8 slot_type[BPF_REG_SIZE];
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};
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/* state of the program:
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* type of all registers and stack info
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*/
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struct bpf_verifier_state {
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struct bpf_reg_state regs[MAX_BPF_REG];
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struct bpf_verifier_state *parent;
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int allocated_stack;
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struct bpf_stack_state *stack;
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};
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/* linked list of verifier states used to prune search */
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struct bpf_verifier_state_list {
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struct bpf_verifier_state state;
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struct bpf_verifier_state_list *next;
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};
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struct bpf_insn_aux_data {
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union {
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enum bpf_reg_type ptr_type; /* pointer type for load/store insns */
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struct bpf_map *map_ptr; /* pointer for call insn into lookup_elem */
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};
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int ctx_field_size; /* the ctx field size for load insn, maybe 0 */
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bool seen; /* this insn was processed by the verifier */
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};
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#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
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#define BPF_VERIFIER_TMP_LOG_SIZE 1024
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struct bpf_verifer_log {
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u32 level;
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char kbuf[BPF_VERIFIER_TMP_LOG_SIZE];
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char __user *ubuf;
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u32 len_used;
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u32 len_total;
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};
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static inline bool bpf_verifier_log_full(const struct bpf_verifer_log *log)
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{
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return log->len_used >= log->len_total - 1;
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}
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struct bpf_verifier_env;
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struct bpf_ext_analyzer_ops {
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int (*insn_hook)(struct bpf_verifier_env *env,
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int insn_idx, int prev_insn_idx);
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};
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/* single container for all structs
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* one verifier_env per bpf_check() call
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*/
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struct bpf_verifier_env {
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struct bpf_prog *prog; /* eBPF program being verified */
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const struct bpf_verifier_ops *ops;
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struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */
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int stack_size; /* number of states to be processed */
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bool strict_alignment; /* perform strict pointer alignment checks */
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struct bpf_verifier_state *cur_state; /* current verifier state */
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struct bpf_verifier_state_list **explored_states; /* search pruning optimization */
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const struct bpf_ext_analyzer_ops *dev_ops; /* device analyzer ops */
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struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
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u32 used_map_cnt; /* number of used maps */
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u32 id_gen; /* used to generate unique reg IDs */
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bool allow_ptr_leaks;
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bool seen_direct_write;
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struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
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struct bpf_verifer_log log;
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};
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static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env)
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{
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return env->cur_state->regs;
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}
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#if defined(CONFIG_NET) && defined(CONFIG_BPF_SYSCALL)
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int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env);
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#else
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static inline int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env)
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{
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return -EOPNOTSUPP;
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}
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#endif
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#endif /* _LINUX_BPF_VERIFIER_H */
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