OwlCyberSecurity - MANAGER

Edit File: bpf_verifier.h

/* SPDX-License-Identifier: GPL-2.0-only */ /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com */ #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_READ32 = 0x1, /* reg was read, so we're sensitive to initial value */ REG_LIVE_READ64 = 0x2, /* likewise, but full 64-bit content matters */ REG_LIVE_READ = REG_LIVE_READ32 | REG_LIVE_READ64, REG_LIVE_WRITTEN = 0x4, /* reg was written first, screening off later reads */ REG_LIVE_DONE = 0x8, /* liveness won't be updating this register anymore */ }; struct bpf_reg_state { /* Ordering of fields matters. See states_equal() */ 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; /* Max size from any of the above. */ unsigned long raw; }; /* 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. * For PTR_TO_SOCKET this is used to share which pointers retain the * same reference to the socket, to determine proper reference freeing. */ 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; /* 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 */ /* parentage chain for liveness checking */ struct bpf_reg_state *parent; /* 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; enum bpf_reg_liveness live; /* 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_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]; }; struct bpf_reference_state { /* 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; }; /* state of the program: * type of all registers and stack info */ struct bpf_func_state { struct bpf_reg_state regs[MAX_BPF_REG]; /* 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; /* The following fields should be last. See copy_func_state() */ int acquired_refs; struct bpf_reference_state *refs; int allocated_stack; struct bpf_stack_state *stack; }; struct bpf_idx_pair { u32 prev_idx; u32 idx; }; struct bpf_id_pair { u32 old; u32 cur; }; /* Maximum number of register states that can exist at once */ #define BPF_ID_MAP_SIZE (MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE) #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; /* * '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 * equvalency, 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 active_spin_lock; bool speculative; /* first and last insn idx of this verifier state */ u32 first_insn_idx; u32 last_insn_idx; /* 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_idx_pair *jmp_history; u32 jmp_history_cnt; }; #define bpf_get_spilled_reg(slot, frame) \ (((slot < frame->allocated_stack / BPF_REG_SIZE) && \ (frame->stack[slot].slot_type[0] == STACK_SPILL)) \ ? &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) \ for (iter = 0, reg = bpf_get_spilled_reg(iter, frame); \ iter < frame->allocated_stack / BPF_REG_SIZE; \ iter++, reg = bpf_get_spilled_reg(iter, frame)) /* 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; int miss_cnt, hit_cnt; }; /* 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) 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 */ struct { u32 map_index; /* index into used_maps[] */ u32 map_off; /* offset from value base address */ }; }; int ctx_field_size; /* the ctx field size for load insn, maybe 0 */ bool seen; /* this insn was processed by the verifier */ bool sanitize_stack_spill; /* subject to Spectre v4 sanitation */ bool zext_dst; /* this insn zero extends dst reg */ u8 alu_state; /* used in combination with alu_limit */ bool prune_point; unsigned int orig_idx; /* original instruction index */ }; #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; } #define BPF_LOG_LEVEL1 1 #define BPF_LOG_LEVEL2 2 #define BPF_LOG_STATS 4 #define BPF_LOG_LEVEL (BPF_LOG_LEVEL1 | BPF_LOG_LEVEL2) #define BPF_LOG_MASK (BPF_LOG_LEVEL | BPF_LOG_STATS) 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 */ u32 linfo_idx; /* The idx to the main_prog->aux->linfo */ u16 stack_depth; /* max. stack depth used by this function */ bool has_tail_call; }; /* 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 */ bool test_state_freq; /* test verifier with different pruning frequency */ struct bpf_verifier_state *cur_state; /* current verifier state */ struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ struct bpf_verifier_state_list *free_list; 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 explore_alu_limits; bool allow_ptr_leaks; bool seen_direct_write; 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 + 1]; struct bpf_id_pair idmap_scratch[BPF_ID_MAP_SIZE]; struct { int *insn_state; int *insn_stack; int cur_stack; } cfg; 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; }; __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_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); #endif /* _LINUX_BPF_VERIFIER_H */