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Diffstat (limited to 'include/linux/bpf_verifier.h')
| -rw-r--r-- | include/linux/bpf_verifier.h | 1065 |
1 files changed, 1021 insertions, 44 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 8e5d31f6faef..130bcbd66f60 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -1,113 +1,1090 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ /* 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/btf.h> /* for struct btf and btf_id() */ #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 (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) +/* size of tmp_str_buf in bpf_verifier. + * we need at least 306 bytes to fit full stack mask representation + * (in the "-8,-16,...,-512" form) + */ +#define TMP_STR_BUF_LEN 320 +/* Patch buffer size */ +#define INSN_BUF_SIZE 32 + +#define ITER_PREFIX "bpf_iter_" + +enum bpf_iter_state { + BPF_ITER_STATE_INVALID, /* for non-first slot */ + BPF_ITER_STATE_ACTIVE, + BPF_ITER_STATE_DRAINED, +}; struct bpf_reg_state { + /* Ordering of fields matters. See states_equal() */ enum bpf_reg_type type; + /* + * Fixed part of pointer offset, pointer types only. + * Or constant delta between "linked" scalars with the same ID. + */ + s32 off; 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 */ + int range; /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | * PTR_TO_MAP_VALUE_OR_NULL */ - struct bpf_map *map_ptr; + struct { + struct bpf_map *map_ptr; + /* To distinguish map lookups from outer map + * the map_uid is non-zero for registers + * pointing to inner maps. + */ + u32 map_uid; + }; + + /* for PTR_TO_BTF_ID */ + struct { + struct btf *btf; + u32 btf_id; + }; + + struct { /* for PTR_TO_MEM | PTR_TO_MEM_OR_NULL */ + u32 mem_size; + u32 dynptr_id; /* for dynptr slices */ + }; + + /* For dynptr stack slots */ + struct { + enum bpf_dynptr_type type; + /* A dynptr is 16 bytes so it takes up 2 stack slots. + * We need to track which slot is the first slot + * to protect against cases where the user may try to + * pass in an address starting at the second slot of the + * dynptr. + */ + bool first_slot; + } dynptr; + + /* For bpf_iter stack slots */ + struct { + /* BTF container and BTF type ID describing + * struct bpf_iter_<type> of an iterator state + */ + struct btf *btf; + u32 btf_id; + /* packing following two fields to fit iter state into 16 bytes */ + enum bpf_iter_state state:2; + int depth:30; + } iter; + + /* For irq stack slots */ + struct { + enum { + IRQ_NATIVE_KFUNC, + IRQ_LOCK_KFUNC, + } kfunc_class; + } irq; + + /* Max size from any of the above. */ + struct { + unsigned long raw1; + unsigned long raw2; + } raw; + + u32 subprogno; /* for PTR_TO_FUNC */ }; - u32 id; + /* 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 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 */ + s32 s32_min_value; /* minimum possible (s32)value */ + s32 s32_max_value; /* maximum possible (s32)value */ + u32 u32_min_value; /* minimum possible (u32)value */ + u32 u32_max_value; /* maximum possible (u32)value */ + /* 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. + * For PTR_TO_MEM_OR_NULL this is used to identify memory allocation + * for the purpose of tracking that it's freed. + * For PTR_TO_SOCKET this is used to share which pointers retain the + * same reference to the socket, to determine proper reference freeing. + * For stack slots that are dynptrs, this is used to track references to + * the dynptr to determine proper reference freeing. + * Similarly to dynptrs, we use ID to track "belonging" of a reference + * to a specific instance of bpf_iter. */ - s64 min_value; - u64 max_value; - u32 min_align; - u32 aux_off; - u32 aux_off_align; - bool value_from_signed; + /* + * Upper bit of ID is used to remember relationship between "linked" + * registers. Example: + * r1 = r2; both will have r1->id == r2->id == N + * r1 += 10; r1->id == N | BPF_ADD_CONST and r1->off == 10 + */ +#define BPF_ADD_CONST (1U << 31) + u32 id; + /* PTR_TO_SOCKET and PTR_TO_TCP_SOCK could be a ptr returned + * from a pointer-cast helper, bpf_sk_fullsock() and + * bpf_tcp_sock(). + * + * Consider the following where "sk" is a reference counted + * pointer returned from "sk = bpf_sk_lookup_tcp();": + * + * 1: sk = bpf_sk_lookup_tcp(); + * 2: if (!sk) { return 0; } + * 3: fullsock = bpf_sk_fullsock(sk); + * 4: if (!fullsock) { bpf_sk_release(sk); return 0; } + * 5: tp = bpf_tcp_sock(fullsock); + * 6: if (!tp) { bpf_sk_release(sk); return 0; } + * 7: bpf_sk_release(sk); + * 8: snd_cwnd = tp->snd_cwnd; // verifier will complain + * + * After bpf_sk_release(sk) at line 7, both "fullsock" ptr and + * "tp" ptr should be invalidated also. In order to do that, + * the reg holding "fullsock" and "sk" need to remember + * the original refcounted ptr id (i.e. sk_reg->id) in ref_obj_id + * such that the verifier can reset all regs which have + * ref_obj_id matching the sk_reg->id. + * + * sk_reg->ref_obj_id is set to sk_reg->id at line 1. + * sk_reg->id will stay as NULL-marking purpose only. + * After NULL-marking is done, sk_reg->id can be reset to 0. + * + * After "fullsock = bpf_sk_fullsock(sk);" at line 3, + * fullsock_reg->ref_obj_id is set to sk_reg->ref_obj_id. + * + * After "tp = bpf_tcp_sock(fullsock);" at line 5, + * tp_reg->ref_obj_id is set to fullsock_reg->ref_obj_id + * which is the same as sk_reg->ref_obj_id. + * + * From the verifier perspective, if sk, fullsock and tp + * are not NULL, they are the same ptr with different + * reg->type. In particular, bpf_sk_release(tp) is also + * allowed and has the same effect as bpf_sk_release(sk). + */ + u32 ref_obj_id; + /* 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. + */ + u32 frameno; + /* Tracks subreg definition. The stored value is the insn_idx of the + * writing insn. This is safe because subreg_def is used before any insn + * patching which only happens after main verification finished. + */ + s32 subreg_def; + /* if (!precise && SCALAR_VALUE) min/max/tnum don't affect safety */ + bool precise; }; 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_MISC, /* BPF program wrote some data into this slot */ + STACK_ZERO, /* BPF program wrote constant zero */ + /* A dynptr is stored in this stack slot. The type of dynptr + * is stored in bpf_stack_state->spilled_ptr.dynptr.type + */ + STACK_DYNPTR, + STACK_ITER, + STACK_IRQ_FLAG, }; #define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ +#define BPF_REGMASK_ARGS ((1 << BPF_REG_1) | (1 << BPF_REG_2) | \ + (1 << BPF_REG_3) | (1 << BPF_REG_4) | \ + (1 << BPF_REG_5)) + +#define BPF_DYNPTR_SIZE sizeof(struct bpf_dynptr_kern) +#define BPF_DYNPTR_NR_SLOTS (BPF_DYNPTR_SIZE / BPF_REG_SIZE) + +struct bpf_stack_state { + struct bpf_reg_state spilled_ptr; + u8 slot_type[BPF_REG_SIZE]; +}; + +struct bpf_reference_state { + /* Each reference object has a type. Ensure REF_TYPE_PTR is zero to + * default to pointer reference on zero initialization of a state. + */ + enum ref_state_type { + REF_TYPE_PTR = (1 << 1), + REF_TYPE_IRQ = (1 << 2), + REF_TYPE_LOCK = (1 << 3), + REF_TYPE_RES_LOCK = (1 << 4), + REF_TYPE_RES_LOCK_IRQ = (1 << 5), + REF_TYPE_LOCK_MASK = REF_TYPE_LOCK | REF_TYPE_RES_LOCK | REF_TYPE_RES_LOCK_IRQ, + } type; + /* Track each reference created with a unique id, even if the same + * instruction creates the reference multiple times (eg, via CALL). + */ + int id; + /* Instruction where the allocation of this reference occurred. This + * is used purely to inform the user of a reference leak. + */ + int insn_idx; + /* Use to keep track of the source object of a lock, to ensure + * it matches on unlock. + */ + void *ptr; +}; + +struct bpf_retval_range { + s32 minval; + s32 maxval; +}; + /* state of the program: * type of all registers and stack info */ -struct bpf_verifier_state { +struct bpf_func_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]; + /* 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_info + * zero == main subprog + */ + u32 subprogno; + /* Every bpf_timer_start will increment async_entry_cnt. + * It's used to distinguish: + * void foo(void) { for(;;); } + * void foo(void) { bpf_timer_set_callback(,foo); } + */ + u32 async_entry_cnt; + struct bpf_retval_range callback_ret_range; + bool in_callback_fn; + bool in_async_callback_fn; + bool in_exception_callback_fn; + /* For callback calling functions that limit number of possible + * callback executions (e.g. bpf_loop) keeps track of current + * simulated iteration number. + * Value in frame N refers to number of times callback with frame + * N+1 was simulated, e.g. for the following call: + * + * bpf_loop(..., fn, ...); | suppose current frame is N + * | fn would be simulated in frame N+1 + * | number of simulations is tracked in frame N + */ + u32 callback_depth; + + /* The following fields should be last. See copy_func_state() */ + /* The state of the stack. Each element of the array describes BPF_REG_SIZE + * (i.e. 8) bytes worth of stack memory. + * stack[0] represents bytes [*(r10-8)..*(r10-1)] + * stack[1] represents bytes [*(r10-16)..*(r10-9)] + * ... + * stack[allocated_stack/8 - 1] represents [*(r10-allocated_stack)..*(r10-allocated_stack+7)] + */ + struct bpf_stack_state *stack; + /* Size of the current stack, in bytes. The stack state is tracked below, in + * `stack`. allocated_stack is always a multiple of BPF_REG_SIZE. + */ + int allocated_stack; }; +#define MAX_CALL_FRAMES 8 + +/* instruction history flags, used in bpf_jmp_history_entry.flags field */ +enum { + /* instruction references stack slot through PTR_TO_STACK register; + * we also store stack's frame number in lower 3 bits (MAX_CALL_FRAMES is 8) + * and accessed stack slot's index in next 6 bits (MAX_BPF_STACK is 512, + * 8 bytes per slot, so slot index (spi) is [0, 63]) + */ + INSN_F_FRAMENO_MASK = 0x7, /* 3 bits */ + + INSN_F_SPI_MASK = 0x3f, /* 6 bits */ + INSN_F_SPI_SHIFT = 3, /* shifted 3 bits to the left */ + + INSN_F_STACK_ACCESS = BIT(9), + + INSN_F_DST_REG_STACK = BIT(10), /* dst_reg is PTR_TO_STACK */ + INSN_F_SRC_REG_STACK = BIT(11), /* src_reg is PTR_TO_STACK */ + /* total 12 bits are used now. */ +}; + +static_assert(INSN_F_FRAMENO_MASK + 1 >= MAX_CALL_FRAMES); +static_assert(INSN_F_SPI_MASK + 1 >= MAX_BPF_STACK / 8); + +struct bpf_jmp_history_entry { + u32 idx; + /* insn idx can't be bigger than 1 million */ + u32 prev_idx : 20; + /* special INSN_F_xxx flags */ + u32 flags : 12; + /* additional registers that need precision tracking when this + * jump is backtracked, vector of six 10-bit records + */ + u64 linked_regs; +}; + +/* Maximum number of register states that can exist at once */ +#define BPF_ID_MAP_SIZE ((MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE) * MAX_CALL_FRAMES) +struct bpf_verifier_state { + /* call stack tracking */ + struct bpf_func_state *frame[MAX_CALL_FRAMES]; + struct bpf_verifier_state *parent; + /* Acquired reference states */ + struct bpf_reference_state *refs; + /* + * 'branches' field is the number of branches left to explore: + * 0 - all possible paths from this state reached bpf_exit or + * were safely pruned + * 1 - at least one path is being explored. + * This state hasn't reached bpf_exit + * 2 - at least two paths are being explored. + * This state is an immediate parent of two children. + * One is fallthrough branch with branches==1 and another + * state is pushed into stack (to be explored later) also with + * branches==1. The parent of this state has branches==1. + * The verifier state tree connected via 'parent' pointer looks like: + * 1 + * 1 + * 2 -> 1 (first 'if' pushed into stack) + * 1 + * 2 -> 1 (second 'if' pushed into stack) + * 1 + * 1 + * 1 bpf_exit. + * + * Once do_check() reaches bpf_exit, it calls update_branch_counts() + * and the verifier state tree will look: + * 1 + * 1 + * 2 -> 1 (first 'if' pushed into stack) + * 1 + * 1 -> 1 (second 'if' pushed into stack) + * 0 + * 0 + * 0 bpf_exit. + * After pop_stack() the do_check() will resume at second 'if'. + * + * If is_state_visited() sees a state with branches > 0 it means + * there is a loop. If such state is exactly equal to the current state + * it's an infinite loop. Note states_equal() checks for states + * equivalency, so two states being 'states_equal' does not mean + * infinite loop. The exact comparison is provided by + * states_maybe_looping() function. It's a stronger pre-check and + * much faster than states_equal(). + * + * This algorithm may not find all possible infinite loops or + * loop iteration count may be too high. + * In such cases BPF_COMPLEXITY_LIMIT_INSNS limit kicks in. + */ + u32 branches; + u32 insn_idx; + u32 curframe; + + u32 acquired_refs; + u32 active_locks; + u32 active_preempt_locks; + u32 active_irq_id; + u32 active_lock_id; + void *active_lock_ptr; + u32 active_rcu_locks; + + bool speculative; + bool in_sleepable; + bool cleaned; + + /* first and last insn idx of this verifier state */ + u32 first_insn_idx; + u32 last_insn_idx; + /* if this state is a backedge state then equal_state + * records cached state to which this state is equal. + */ + struct bpf_verifier_state *equal_state; + /* jmp history recorded from first to last. + * backtracking is using it to go from last to first. + * For most states jmp_history_cnt is [0-3]. + * For loops can go up to ~40. + */ + struct bpf_jmp_history_entry *jmp_history; + u32 jmp_history_cnt; + u32 dfs_depth; + u32 callback_unroll_depth; + u32 may_goto_depth; +}; + +#define bpf_get_spilled_reg(slot, frame, mask) \ + (((slot < frame->allocated_stack / BPF_REG_SIZE) && \ + ((1 << frame->stack[slot].slot_type[BPF_REG_SIZE - 1]) & (mask))) \ + ? &frame->stack[slot].spilled_ptr : NULL) + +/* Iterate over 'frame', setting 'reg' to either NULL or a spilled register. */ +#define bpf_for_each_spilled_reg(iter, frame, reg, mask) \ + for (iter = 0, reg = bpf_get_spilled_reg(iter, frame, mask); \ + iter < frame->allocated_stack / BPF_REG_SIZE; \ + iter++, reg = bpf_get_spilled_reg(iter, frame, mask)) + +#define bpf_for_each_reg_in_vstate_mask(__vst, __state, __reg, __mask, __expr) \ + ({ \ + struct bpf_verifier_state *___vstate = __vst; \ + int ___i, ___j; \ + for (___i = 0; ___i <= ___vstate->curframe; ___i++) { \ + struct bpf_reg_state *___regs; \ + __state = ___vstate->frame[___i]; \ + ___regs = __state->regs; \ + for (___j = 0; ___j < MAX_BPF_REG; ___j++) { \ + __reg = &___regs[___j]; \ + (void)(__expr); \ + } \ + bpf_for_each_spilled_reg(___j, __state, __reg, __mask) { \ + if (!__reg) \ + continue; \ + (void)(__expr); \ + } \ + } \ + }) + +/* Invoke __expr over regsiters in __vst, setting __state and __reg */ +#define bpf_for_each_reg_in_vstate(__vst, __state, __reg, __expr) \ + bpf_for_each_reg_in_vstate_mask(__vst, __state, __reg, 1 << STACK_SPILL, __expr) + /* 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; + struct list_head node; + u32 miss_cnt; + u32 hit_cnt:31; + u32 in_free_list:1; +}; + +struct bpf_loop_inline_state { + unsigned int initialized:1; /* set to true upon first entry */ + unsigned int fit_for_inline:1; /* true if callback function is the same + * at each call and flags are always zero + */ + u32 callback_subprogno; /* valid when fit_for_inline is true */ +}; + +/* pointer and state for maps */ +struct bpf_map_ptr_state { + struct bpf_map *map_ptr; + bool poison; + bool unpriv; +}; + +/* Possible states for alu_state member. */ +#define BPF_ALU_SANITIZE_SRC (1U << 0) +#define BPF_ALU_SANITIZE_DST (1U << 1) +#define BPF_ALU_NEG_VALUE (1U << 2) +#define BPF_ALU_NON_POINTER (1U << 3) +#define BPF_ALU_IMMEDIATE (1U << 4) +#define BPF_ALU_SANITIZE (BPF_ALU_SANITIZE_SRC | \ + BPF_ALU_SANITIZE_DST) + +/* + * An array of BPF instructions. + * Primary usage: return value of bpf_insn_successors. + */ +struct bpf_iarray { + int cnt; + u32 items[]; }; struct bpf_insn_aux_data { union { enum bpf_reg_type ptr_type; /* pointer type for load/store insns */ - struct bpf_map *map_ptr; /* pointer for call insn into lookup_elem */ + struct bpf_map_ptr_state map_ptr_state; + s32 call_imm; /* saved imm field of call insn */ + u32 alu_limit; /* limit for add/sub register with pointer */ + struct { + u32 map_index; /* index into used_maps[] */ + u32 map_off; /* offset from value base address */ + }; + struct { + enum bpf_reg_type reg_type; /* type of pseudo_btf_id */ + union { + struct { + struct btf *btf; + u32 btf_id; /* btf_id for struct typed var */ + }; + u32 mem_size; /* mem_size for non-struct typed var */ + }; + } btf_var; + /* if instruction is a call to bpf_loop this field tracks + * the state of the relevant registers to make decision about inlining + */ + struct bpf_loop_inline_state loop_inline_state; }; + union { + /* remember the size of type passed to bpf_obj_new to rewrite R1 */ + u64 obj_new_size; + /* remember the offset of node field within type to rewrite */ + u64 insert_off; + }; + struct bpf_iarray *jt; /* jump table for gotox or bpf_tailcall call instruction */ + struct btf_struct_meta *kptr_struct_meta; + u64 map_key_state; /* constant (32 bit) key tracking for maps */ int ctx_field_size; /* the ctx field size for load insn, maybe 0 */ - int converted_op_size; /* the valid value width after perceived conversion */ + u32 seen; /* this insn was processed by the verifier at env->pass_cnt */ + bool nospec; /* do not execute this instruction speculatively */ + bool nospec_result; /* result is unsafe under speculation, nospec must follow */ + bool zext_dst; /* this insn zero extends dst reg */ + bool needs_zext; /* alu op needs to clear upper bits */ + bool non_sleepable; /* helper/kfunc may be called from non-sleepable context */ + bool is_iter_next; /* bpf_iter_<type>_next() kfunc call */ + bool call_with_percpu_alloc_ptr; /* {this,per}_cpu_ptr() with prog percpu alloc */ + u8 alu_state; /* used in combination with alu_limit */ + /* true if STX or LDX instruction is a part of a spill/fill + * pattern for a bpf_fastcall call. + */ + u8 fastcall_pattern:1; + /* for CALL instructions, a number of spill/fill pairs in the + * bpf_fastcall pattern. + */ + u8 fastcall_spills_num:3; + u8 arg_prog:4; + + /* below fields are initialized once */ + unsigned int orig_idx; /* original instruction index */ + bool jmp_point; + bool prune_point; + /* ensure we check state equivalence and save state checkpoint and + * this instruction, regardless of any heuristics + */ + bool force_checkpoint; + /* true if instruction is a call to a helper function that + * accepts callback function as a parameter. + */ + bool calls_callback; + /* + * CFG strongly connected component this instruction belongs to, + * zero if it is a singleton SCC. + */ + u32 scc; + /* registers alive before this instruction. */ + u16 live_regs_before; }; #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ +#define MAX_USED_BTFS 64 /* max number of BTFs accessed by one BPF program */ + +#define BPF_VERIFIER_TMP_LOG_SIZE 1024 + +struct bpf_verifier_log { + /* Logical start and end positions of a "log window" of the verifier log. + * start_pos == 0 means we haven't truncated anything. + * Once truncation starts to happen, start_pos + len_total == end_pos, + * except during log reset situations, in which (end_pos - start_pos) + * might get smaller than len_total (see bpf_vlog_reset()). + * Generally, (end_pos - start_pos) gives number of useful data in + * user log buffer. + */ + u64 start_pos; + u64 end_pos; + char __user *ubuf; + u32 level; + u32 len_total; + u32 len_max; + char kbuf[BPF_VERIFIER_TMP_LOG_SIZE]; +}; + +#define BPF_LOG_LEVEL1 1 +#define BPF_LOG_LEVEL2 2 +#define BPF_LOG_STATS 4 +#define BPF_LOG_FIXED 8 +#define BPF_LOG_LEVEL (BPF_LOG_LEVEL1 | BPF_LOG_LEVEL2) +#define BPF_LOG_MASK (BPF_LOG_LEVEL | BPF_LOG_STATS | BPF_LOG_FIXED) +#define BPF_LOG_KERNEL (BPF_LOG_MASK + 1) /* kernel internal flag */ +#define BPF_LOG_MIN_ALIGNMENT 8U +#define BPF_LOG_ALIGNMENT 40U + +static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) +{ + return log && log->level; +} + +#define BPF_MAX_SUBPROGS 256 + +struct bpf_subprog_arg_info { + enum bpf_arg_type arg_type; + union { + u32 mem_size; + u32 btf_id; + }; +}; + +enum priv_stack_mode { + PRIV_STACK_UNKNOWN, + NO_PRIV_STACK, + PRIV_STACK_ADAPTIVE, +}; + +struct bpf_subprog_info { + /* 'start' has to be the first field otherwise find_subprog() won't work */ + u32 start; /* insn idx of function entry point */ + u32 linfo_idx; /* The idx to the main_prog->aux->linfo */ + u32 postorder_start; /* The idx to the env->cfg.insn_postorder */ + u32 exit_idx; /* Index of one of the BPF_EXIT instructions in this subprogram */ + u16 stack_depth; /* max. stack depth used by this function */ + u16 stack_extra; + /* offsets in range [stack_depth .. fastcall_stack_off) + * are used for bpf_fastcall spills and fills. + */ + s16 fastcall_stack_off; + bool has_tail_call: 1; + bool tail_call_reachable: 1; + bool has_ld_abs: 1; + bool is_cb: 1; + bool is_async_cb: 1; + bool is_exception_cb: 1; + bool args_cached: 1; + /* true if bpf_fastcall stack region is used by functions that can't be inlined */ + bool keep_fastcall_stack: 1; + bool changes_pkt_data: 1; + bool might_sleep: 1; + u8 arg_cnt:3; + + enum priv_stack_mode priv_stack_mode; + struct bpf_subprog_arg_info args[MAX_BPF_FUNC_REG_ARGS]; +}; struct bpf_verifier_env; -struct bpf_ext_analyzer_ops { - int (*insn_hook)(struct bpf_verifier_env *env, - int insn_idx, int prev_insn_idx); + +struct backtrack_state { + struct bpf_verifier_env *env; + u32 frame; + u32 reg_masks[MAX_CALL_FRAMES]; + u64 stack_masks[MAX_CALL_FRAMES]; +}; + +struct bpf_id_pair { + u32 old; + u32 cur; +}; + +struct bpf_idmap { + u32 tmp_id_gen; + struct bpf_id_pair map[BPF_ID_MAP_SIZE]; +}; + +struct bpf_idset { + u32 count; + u32 ids[BPF_ID_MAP_SIZE]; }; +/* see verifier.c:compute_scc_callchain() */ +struct bpf_scc_callchain { + /* call sites from bpf_verifier_state->frame[*]->callsite leading to this SCC */ + u32 callsites[MAX_CALL_FRAMES - 1]; + /* last frame in a chain is identified by SCC id */ + u32 scc; +}; + +/* verifier state waiting for propagate_backedges() */ +struct bpf_scc_backedge { + struct bpf_scc_backedge *next; + struct bpf_verifier_state state; +}; + +struct bpf_scc_visit { + struct bpf_scc_callchain callchain; + /* first state in current verification path that entered SCC + * identified by the callchain + */ + struct bpf_verifier_state *entry_state; + struct bpf_scc_backedge *backedges; /* list of backedges */ + u32 num_backedges; +}; + +/* An array of bpf_scc_visit structs sharing tht same bpf_scc_callchain->scc + * but having different bpf_scc_callchain->callsites. + */ +struct bpf_scc_info { + u32 num_visits; + struct bpf_scc_visit visits[]; +}; + +struct bpf_liveness; + /* 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 module *attach_btf_mod; /* The owner module of prog->aux->attach_btf */ 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 */ + bool test_state_freq; /* test verifier with different pruning frequency */ + bool test_reg_invariants; /* fail verification on register invariants violations */ + struct bpf_verifier_state *cur_state; /* current verifier state */ + /* Search pruning optimization, array of list_heads for + * lists of struct bpf_verifier_state_list. + */ + struct list_head *explored_states; + struct list_head free_list; /* list of struct bpf_verifier_state_list */ struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ + struct btf_mod_pair used_btfs[MAX_USED_BTFS]; /* array of BTF's used by BPF program */ + struct bpf_map *insn_array_maps[MAX_USED_MAPS]; /* array of INSN_ARRAY map's to be relocated */ u32 used_map_cnt; /* number of used maps */ + u32 used_btf_cnt; /* number of used BTF objects */ + u32 insn_array_map_cnt; /* number of used maps of type BPF_MAP_TYPE_INSN_ARRAY */ u32 id_gen; /* used to generate unique reg IDs */ + u32 hidden_subprog_cnt; /* number of hidden subprogs */ + int exception_callback_subprog; + bool explore_alu_limits; bool allow_ptr_leaks; + /* Allow access to uninitialized stack memory. Writes with fixed offset are + * always allowed, so this refers to reads (with fixed or variable offset), + * to writes with variable offset and to indirect (helper) accesses. + */ + bool allow_uninit_stack; + bool bpf_capable; + bool bypass_spec_v1; + bool bypass_spec_v4; bool seen_direct_write; - bool varlen_map_value_access; + bool seen_exception; struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */ + const struct bpf_line_info *prev_linfo; + struct bpf_verifier_log log; + struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 2]; /* max + 2 for the fake and exception subprogs */ + union { + struct bpf_idmap idmap_scratch; + struct bpf_idset idset_scratch; + }; + struct { + int *insn_state; + int *insn_stack; + /* + * vector of instruction indexes sorted in post-order, grouped by subprogram, + * see bpf_subprog_info->postorder_start. + */ + int *insn_postorder; + int cur_stack; + /* current position in the insn_postorder vector */ + int cur_postorder; + } cfg; + struct backtrack_state bt; + struct bpf_jmp_history_entry *cur_hist_ent; + u32 pass_cnt; /* number of times do_check() was called */ + u32 subprog_cnt; + /* number of instructions analyzed by the verifier */ + u32 prev_insn_processed, insn_processed; + /* number of jmps, calls, exits analyzed so far */ + u32 prev_jmps_processed, jmps_processed; + /* total verification time */ + u64 verification_time; + /* maximum number of verifier states kept in 'branching' instructions */ + u32 max_states_per_insn; + /* total number of allocated verifier states */ + u32 total_states; + /* some states are freed during program analysis. + * this is peak number of states. this number dominates kernel + * memory consumption during verification + */ + u32 peak_states; + /* longest register parentage chain walked for liveness marking */ + u32 longest_mark_read_walk; + u32 free_list_size; + u32 explored_states_size; + u32 num_backedges; + bpfptr_t fd_array; + + /* bit mask to keep track of whether a register has been accessed + * since the last time the function state was printed + */ + u32 scratched_regs; + /* Same as scratched_regs but for stack slots */ + u64 scratched_stack_slots; + u64 prev_log_pos, prev_insn_print_pos; + /* buffer used to temporary hold constants as scalar registers */ + struct bpf_reg_state fake_reg[2]; + /* buffer used to generate temporary string representations, + * e.g., in reg_type_str() to generate reg_type string + */ + char tmp_str_buf[TMP_STR_BUF_LEN]; + struct bpf_insn insn_buf[INSN_BUF_SIZE]; + struct bpf_insn epilogue_buf[INSN_BUF_SIZE]; + struct bpf_scc_callchain callchain_buf; + struct bpf_liveness *liveness; + /* array of pointers to bpf_scc_info indexed by SCC id */ + struct bpf_scc_info **scc_info; + u32 scc_cnt; + struct bpf_iarray *succ; + struct bpf_iarray *gotox_tmp_buf; }; -int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, - void *priv); +static inline struct bpf_func_info_aux *subprog_aux(struct bpf_verifier_env *env, int subprog) +{ + return &env->prog->aux->func_info_aux[subprog]; +} + +static inline struct bpf_subprog_info *subprog_info(struct bpf_verifier_env *env, int subprog) +{ + return &env->subprog_info[subprog]; +} + +__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, ...); +__printf(2, 3) void bpf_log(struct bpf_verifier_log *log, + const char *fmt, ...); +int bpf_vlog_init(struct bpf_verifier_log *log, u32 log_level, + char __user *log_buf, u32 log_size); +void bpf_vlog_reset(struct bpf_verifier_log *log, u64 new_pos); +int bpf_vlog_finalize(struct bpf_verifier_log *log, u32 *log_size_actual); + +__printf(3, 4) void verbose_linfo(struct bpf_verifier_env *env, + u32 insn_off, + const char *prefix_fmt, ...); + +#define verifier_bug_if(cond, env, fmt, args...) \ + ({ \ + bool __cond = (cond); \ + if (unlikely(__cond)) \ + verifier_bug(env, fmt " (" #cond ")", ##args); \ + (__cond); \ + }) +#define verifier_bug(env, fmt, args...) \ + ({ \ + BPF_WARN_ONCE(1, "verifier bug: " fmt "\n", ##args); \ + bpf_log(&env->log, "verifier bug: " fmt "\n", ##args); \ + }) + +static inline struct bpf_func_state *cur_func(struct bpf_verifier_env *env) +{ + struct bpf_verifier_state *cur = env->cur_state; + + return cur->frame[cur->curframe]; +} + +static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env) +{ + return cur_func(env)->regs; +} + +int bpf_prog_offload_verifier_prep(struct bpf_prog *prog); +int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env, + int insn_idx, int prev_insn_idx); +int bpf_prog_offload_finalize(struct bpf_verifier_env *env); +void +bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off, + struct bpf_insn *insn); +void +bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt); + +/* this lives here instead of in bpf.h because it needs to dereference tgt_prog */ +static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog, + struct btf *btf, u32 btf_id) +{ + if (tgt_prog) + return ((u64)tgt_prog->aux->id << 32) | btf_id; + else + return ((u64)btf_obj_id(btf) << 32) | 0x80000000 | btf_id; +} + +/* unpack the IDs from the key as constructed above */ +static inline void bpf_trampoline_unpack_key(u64 key, u32 *obj_id, u32 *btf_id) +{ + if (obj_id) + *obj_id = key >> 32; + if (btf_id) + *btf_id = key & 0x7FFFFFFF; +} + +int bpf_check_attach_target(struct bpf_verifier_log *log, + const struct bpf_prog *prog, + const struct bpf_prog *tgt_prog, + u32 btf_id, + struct bpf_attach_target_info *tgt_info); +void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab); + +int mark_chain_precision(struct bpf_verifier_env *env, int regno); + +#define BPF_BASE_TYPE_MASK GENMASK(BPF_BASE_TYPE_BITS - 1, 0) + +/* extract base type from bpf_{arg, return, reg}_type. */ +static inline u32 base_type(u32 type) +{ + return type & BPF_BASE_TYPE_MASK; +} + +/* extract flags from an extended type. See bpf_type_flag in bpf.h. */ +static inline u32 type_flag(u32 type) +{ + return type & ~BPF_BASE_TYPE_MASK; +} + +/* only use after check_attach_btf_id() */ +static inline enum bpf_prog_type resolve_prog_type(const struct bpf_prog *prog) +{ + return (prog->type == BPF_PROG_TYPE_EXT && prog->aux->saved_dst_prog_type) ? + prog->aux->saved_dst_prog_type : prog->type; +} + +static inline bool bpf_prog_check_recur(const struct bpf_prog *prog) +{ + switch (resolve_prog_type(prog)) { + case BPF_PROG_TYPE_TRACING: + return prog->expected_attach_type != BPF_TRACE_ITER; + case BPF_PROG_TYPE_STRUCT_OPS: + return prog->aux->jits_use_priv_stack; + case BPF_PROG_TYPE_LSM: + case BPF_PROG_TYPE_SYSCALL: + return false; + default: + return true; + } +} + +#define BPF_REG_TRUSTED_MODIFIERS (MEM_ALLOC | PTR_TRUSTED | NON_OWN_REF) + +static inline bool bpf_type_has_unsafe_modifiers(u32 type) +{ + return type_flag(type) & ~BPF_REG_TRUSTED_MODIFIERS; +} + +static inline bool type_is_ptr_alloc_obj(u32 type) +{ + return base_type(type) == PTR_TO_BTF_ID && type_flag(type) & MEM_ALLOC; +} + +static inline bool type_is_non_owning_ref(u32 type) +{ + return type_is_ptr_alloc_obj(type) && type_flag(type) & NON_OWN_REF; +} + +static inline bool type_is_pkt_pointer(enum bpf_reg_type type) +{ + type = base_type(type); + return type == PTR_TO_PACKET || + type == PTR_TO_PACKET_META; +} + +static inline bool type_is_sk_pointer(enum bpf_reg_type type) +{ + return type == PTR_TO_SOCKET || + type == PTR_TO_SOCK_COMMON || + type == PTR_TO_TCP_SOCK || + type == PTR_TO_XDP_SOCK; +} + +static inline bool type_may_be_null(u32 type) +{ + return type & PTR_MAYBE_NULL; +} + +static inline void mark_reg_scratched(struct bpf_verifier_env *env, u32 regno) +{ + env->scratched_regs |= 1U << regno; +} + +static inline void mark_stack_slot_scratched(struct bpf_verifier_env *env, u32 spi) +{ + env->scratched_stack_slots |= 1ULL << spi; +} + +static inline bool reg_scratched(const struct bpf_verifier_env *env, u32 regno) +{ + return (env->scratched_regs >> regno) & 1; +} + +static inline bool stack_slot_scratched(const struct bpf_verifier_env *env, u64 regno) +{ + return (env->scratched_stack_slots >> regno) & 1; +} + +static inline bool verifier_state_scratched(const struct bpf_verifier_env *env) +{ + return env->scratched_regs || env->scratched_stack_slots; +} + +static inline void mark_verifier_state_clean(struct bpf_verifier_env *env) +{ + env->scratched_regs = 0U; + env->scratched_stack_slots = 0ULL; +} + +/* Used for printing the entire verifier state. */ +static inline void mark_verifier_state_scratched(struct bpf_verifier_env *env) +{ + env->scratched_regs = ~0U; + env->scratched_stack_slots = ~0ULL; +} + +static inline bool bpf_stack_narrow_access_ok(int off, int fill_size, int spill_size) +{ +#ifdef __BIG_ENDIAN + off -= spill_size - fill_size; +#endif + + return !(off % BPF_REG_SIZE); +} + +static inline bool insn_is_gotox(struct bpf_insn *insn) +{ + return BPF_CLASS(insn->code) == BPF_JMP && + BPF_OP(insn->code) == BPF_JA && + BPF_SRC(insn->code) == BPF_X; +} + +const char *reg_type_str(struct bpf_verifier_env *env, enum bpf_reg_type type); +const char *dynptr_type_str(enum bpf_dynptr_type type); +const char *iter_type_str(const struct btf *btf, u32 btf_id); +const char *iter_state_str(enum bpf_iter_state state); + +void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_verifier_state *vstate, + u32 frameno, bool print_all); +void print_insn_state(struct bpf_verifier_env *env, const struct bpf_verifier_state *vstate, + u32 frameno); + +struct bpf_subprog_info *bpf_find_containing_subprog(struct bpf_verifier_env *env, int off); +int bpf_jmp_offset(struct bpf_insn *insn); +struct bpf_iarray *bpf_insn_successors(struct bpf_verifier_env *env, u32 idx); +void bpf_fmt_stack_mask(char *buf, ssize_t buf_sz, u64 stack_mask); +bool bpf_calls_callback(struct bpf_verifier_env *env, int insn_idx); + +int bpf_stack_liveness_init(struct bpf_verifier_env *env); +void bpf_stack_liveness_free(struct bpf_verifier_env *env); +int bpf_update_live_stack(struct bpf_verifier_env *env); +int bpf_mark_stack_read(struct bpf_verifier_env *env, u32 frameno, u32 insn_idx, u64 mask); +void bpf_mark_stack_write(struct bpf_verifier_env *env, u32 frameno, u64 mask); +int bpf_reset_stack_write_marks(struct bpf_verifier_env *env, u32 insn_idx); +int bpf_commit_stack_write_marks(struct bpf_verifier_env *env); +int bpf_live_stack_query_init(struct bpf_verifier_env *env, struct bpf_verifier_state *st); +bool bpf_stack_slot_alive(struct bpf_verifier_env *env, u32 frameno, u32 spi); +void bpf_reset_live_stack_callchain(struct bpf_verifier_env *env); #endif /* _LINUX_BPF_VERIFIER_H */ |