Edit File: bpf_verifier.h
/* 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_VERIFIER_H #define _LINUX_BPF_VERIFIER_H 1 #include <linux/bpf.h> /* for enum bpf_reg_type */ #include <linux/filter.h> /* for MAX_BPF_STACK */ #include <linux/tnum.h> /* Maximum variable offset umax_value permitted when resolving memory accesses. * In practice this is far bigger than any realistic pointer offset; this limit * ensures that umax_value + (int)off + (int)size cannot overflow a u64. */ #define BPF_MAX_VAR_OFF (1 << 29) /* Maximum variable size permitted for ARG_CONST_SIZE[_OR_ZERO]. This ensures * that converting umax_value to int cannot overflow. */ #define BPF_MAX_VAR_SIZ (1 << 29) /* Liveness marks, used for registers and spilled-regs (in stack slots). * Read marks propagate upwards until they find a write mark; they record that * "one of this state's descendants read this reg" (and therefore the reg is * relevant for states_equal() checks). * Write marks collect downwards and do not propagate; they record that "the * straight-line code that reached this state (from its parent) wrote this reg" * (and therefore that reads propagated from this state or its descendants * should not propagate to its parent). * A state with a write mark can receive read marks; it just won't propagate * them to its parent, since the write mark is a property, not of the state, * but of the link between it and its parent. See mark_reg_read() and * mark_stack_slot_read() in kernel/bpf/verifier.c. */ enum bpf_reg_liveness { REG_LIVE_NONE = 0, /* reg hasn't been read or written this branch */ REG_LIVE_READ, /* reg was read, so we're sensitive to initial value */ REG_LIVE_WRITTEN, /* reg was written first, screening off later reads */ }; struct bpf_reg_state { enum bpf_reg_type type; union { /* valid when type == PTR_TO_PACKET */ u16 range; /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | * PTR_TO_MAP_VALUE_OR_NULL */ struct bpf_map *map_ptr; }; /* Fixed part of pointer offset, pointer types only */ s32 off; /* For PTR_TO_PACKET, used to find other pointers with the same variable * offset, so they can share range knowledge. * For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we * came from, when one is tested for != NULL. */ u32 id; /* Ordering of fields matters. See states_equal() */ /* For scalar types (SCALAR_VALUE), this represents our knowledge of * the actual value. * For pointer types, this represents the variable part of the offset * from the pointed-to object, and is shared with all bpf_reg_states * with the same id as us. */ struct tnum var_off; /* Used to determine if any memory access using this register will * result in a bad access. * These refer to the same value as var_off, not necessarily the actual * contents of the register. */ s64 smin_value; /* minimum possible (s64)value */ s64 smax_value; /* maximum possible (s64)value */ u64 umin_value; /* minimum possible (u64)value */ u64 umax_value; /* maximum possible (u64)value */ /* Inside the callee two registers can be both PTR_TO_STACK like * R1=fp-8 and R2=fp-8, but one of them points to this function stack * while another to the caller's stack. To differentiate them 'frameno' * is used which is an index in bpf_verifier_state->frame[] array * pointing to bpf_func_state. * This field must be second to last, for states_equal() reasons. */ u32 frameno; /* This field must be last, for states_equal() reasons. */ enum bpf_reg_liveness live; }; 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 */ STACK_ZERO, /* BPF program wrote constant zero */ }; #define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ struct bpf_stack_state { struct bpf_reg_state spilled_ptr; u8 slot_type[BPF_REG_SIZE]; }; /* state of the program: * type of all registers and stack info */ struct bpf_func_state { struct bpf_reg_state regs[MAX_BPF_REG]; struct bpf_verifier_state *parent; /* index of call instruction that called into this func */ int callsite; /* stack frame number of this function state from pov of * enclosing bpf_verifier_state. * 0 = main function, 1 = first callee. */ u32 frameno; /* subprog number == index within subprog_stack_depth * zero == main subprog */ u32 subprogno; /* should be second to last. See copy_func_state() */ int allocated_stack; struct bpf_stack_state *stack; }; #define MAX_CALL_FRAMES 8 struct bpf_verifier_state { /* call stack tracking */ struct bpf_func_state *frame[MAX_CALL_FRAMES]; struct bpf_verifier_state *parent; u32 curframe; bool speculative; }; /* linked list of verifier states used to prune search */ struct bpf_verifier_state_list { struct bpf_verifier_state state; struct bpf_verifier_state_list *next; }; /* Possible states for alu_state member. */ #define BPF_ALU_SANITIZE_SRC 1U #define BPF_ALU_SANITIZE_DST 2U #define BPF_ALU_NEG_VALUE (1U << 2) #define BPF_ALU_SANITIZE (BPF_ALU_SANITIZE_SRC | \ BPF_ALU_SANITIZE_DST) struct bpf_insn_aux_data { union { enum bpf_reg_type ptr_type; /* pointer type for load/store insns */ unsigned long map_state; /* pointer/poison value for maps */ s32 call_imm; /* saved imm field of call insn */ u32 alu_limit; /* limit for add/sub register with pointer */ }; int ctx_field_size; /* the ctx field size for load insn, maybe 0 */ int sanitize_stack_off; /* stack slot to be cleared */ bool seen; /* this insn was processed by the verifier */ u8 alu_state; /* used in combination with alu_limit */ }; #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ #define BPF_VERIFIER_TMP_LOG_SIZE 1024 struct bpf_verifier_log { u32 level; char kbuf[BPF_VERIFIER_TMP_LOG_SIZE]; char __user *ubuf; u32 len_used; u32 len_total; }; static inline bool bpf_verifier_log_full(const struct bpf_verifier_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); }; static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) { return log->level && log->ubuf && !bpf_verifier_log_full(log); } #define BPF_MAX_SUBPROGS 256 struct bpf_subprog_info { u32 start; /* insn idx of function entry point */ u16 stack_depth; /* max. stack depth used by this function */ }; /* single container for all structs * one verifier_env per bpf_check() call */ struct bpf_verifier_env { u32 insn_idx; u32 prev_insn_idx; struct bpf_prog *prog; /* eBPF program being verified */ const struct bpf_verifier_ops *ops; struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */ int stack_size; /* number of states to be processed */ 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 *analyzer_ops; /* external analyzer ops */ void *analyzer_priv; /* pointer to external analyzer'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; bool seen_direct_write; struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */ struct bpf_verifier_log log; struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1]; u32 subprog_cnt; }; __printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt, va_list args); __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env, const char *fmt, ...); static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env) { struct bpf_verifier_state *cur = env->cur_state; return cur->frame[cur->curframe]->regs; } int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, void *priv); #endif /* _LINUX_BPF_VERIFIER_H */