diff options
Diffstat (limited to 'include/linux/bpf_verifier.h')
| -rw-r--r-- | include/linux/bpf_verifier.h | 127 |
1 files changed, 97 insertions, 30 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 8e5d31f6faef..c561b986bab0 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -9,41 +9,75 @@ #include <linux/bpf.h> /* for enum bpf_reg_type */ #include <linux/filter.h> /* for MAX_BPF_STACK */ +#include <linux/tnum.h> - /* Just some arbitrary values so we can safely do math without overflowing and - * are obviously wrong for any sort of memory access. - */ -#define BPF_REGISTER_MAX_RANGE (1024 * 1024 * 1024) -#define BPF_REGISTER_MIN_RANGE -1 +/* 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 (1ULL << 31) +/* 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 INT_MAX + +/* 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 == CONST_IMM | PTR_TO_STACK | UNKNOWN_VALUE */ - s64 imm; - - /* valid when type == PTR_TO_PACKET* */ - struct { - u16 off; - u16 range; - }; + /* 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 two fields must be last. - * See states_equal() + * result in a bad access. + * These refer to the same value as var_off, not necessarily the actual + * contents of the register. */ - s64 min_value; - u64 max_value; - u32 min_align; - u32 aux_off; - u32 aux_off_align; - bool value_from_signed; + 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 */ + /* This field must be last, for states_equal() reasons. */ + enum bpf_reg_liveness live; }; enum bpf_stack_slot_type { @@ -54,13 +88,19 @@ enum bpf_stack_slot_type { #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_verifier_state { struct bpf_reg_state regs[MAX_BPF_REG]; - u8 stack_slot_type[MAX_BPF_STACK]; - struct bpf_reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE]; + struct bpf_verifier_state *parent; + int allocated_stack; + struct bpf_stack_state *stack; }; /* linked list of verifier states used to prune search */ @@ -75,11 +115,26 @@ struct bpf_insn_aux_data { struct bpf_map *map_ptr; /* pointer for call insn into lookup_elem */ }; int ctx_field_size; /* the ctx field size for load insn, maybe 0 */ - int converted_op_size; /* the valid value width after perceived conversion */ + bool seen; /* this insn was processed by the verifier */ }; #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ +#define BPF_VERIFIER_TMP_LOG_SIZE 1024 + +struct bpf_verifer_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_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, @@ -91,23 +146,35 @@ struct bpf_ext_analyzer_ops { */ struct bpf_verifier_env { 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 *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 */ + 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 */ bool allow_ptr_leaks; bool seen_direct_write; - bool varlen_map_value_access; struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */ + + struct bpf_verifer_log log; }; -int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, - void *priv); +static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env) +{ + return env->cur_state->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 #endif /* _LINUX_BPF_VERIFIER_H */ |