diff options
| -rw-r--r-- | kernel/bpf/verifier.c | 62 |
1 files changed, 61 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 5c708eb30664..c1169ee1bc7c 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -504,6 +504,15 @@ static bool is_dynptr_ref_function(enum bpf_func_id func_id) return func_id == BPF_FUNC_dynptr_data; } +static bool is_callback_calling_function(enum bpf_func_id func_id) +{ + return func_id == BPF_FUNC_for_each_map_elem || + func_id == BPF_FUNC_timer_set_callback || + func_id == BPF_FUNC_find_vma || + func_id == BPF_FUNC_loop || + func_id == BPF_FUNC_user_ringbuf_drain; +} + static bool helper_multiple_ref_obj_use(enum bpf_func_id func_id, const struct bpf_map *map) { @@ -1677,7 +1686,7 @@ static void __mark_reg_unknown(const struct bpf_verifier_env *env, reg->type = SCALAR_VALUE; reg->var_off = tnum_unknown; reg->frameno = 0; - reg->precise = env->subprog_cnt > 1 || !env->bpf_capable; + reg->precise = !env->bpf_capable; __mark_reg_unbounded(reg); } @@ -2646,6 +2655,11 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, if (opcode == BPF_CALL) { if (insn->src_reg == BPF_PSEUDO_CALL) return -ENOTSUPP; + /* BPF helpers that invoke callback subprogs are + * equivalent to BPF_PSEUDO_CALL above + */ + if (insn->src_reg == 0 && is_callback_calling_function(insn->imm)) + return -ENOTSUPP; /* regular helper call sets R0 */ *reg_mask &= ~1; if (*reg_mask & 0x3f) { @@ -2809,12 +2823,42 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int frame, int r return 0; if (!reg_mask && !stack_mask) return 0; + for (;;) { DECLARE_BITMAP(mask, 64); u32 history = st->jmp_history_cnt; if (env->log.level & BPF_LOG_LEVEL2) verbose(env, "last_idx %d first_idx %d\n", last_idx, first_idx); + + if (last_idx < 0) { + /* we are at the entry into subprog, which + * is expected for global funcs, but only if + * requested precise registers are R1-R5 + * (which are global func's input arguments) + */ + if (st->curframe == 0 && + st->frame[0]->subprogno > 0 && + st->frame[0]->callsite == BPF_MAIN_FUNC && + stack_mask == 0 && (reg_mask & ~0x3e) == 0) { + bitmap_from_u64(mask, reg_mask); + for_each_set_bit(i, mask, 32) { + reg = &st->frame[0]->regs[i]; + if (reg->type != SCALAR_VALUE) { + reg_mask &= ~(1u << i); + continue; + } + reg->precise = true; + } + return 0; + } + + verbose(env, "BUG backtracing func entry subprog %d reg_mask %x stack_mask %llx\n", + st->frame[0]->subprogno, reg_mask, stack_mask); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + for (i = last_idx;;) { if (skip_first) { err = 0; @@ -6602,6 +6646,10 @@ typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env, struct bpf_func_state *callee, int insn_idx); +static int set_callee_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, int insn_idx); + static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx, int subprog, set_callee_state_fn set_callee_state_cb) @@ -6652,6 +6700,16 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn } } + /* set_callee_state is used for direct subprog calls, but we are + * interested in validating only BPF helpers that can call subprogs as + * callbacks + */ + if (set_callee_state_cb != set_callee_state && !is_callback_calling_function(insn->imm)) { + verbose(env, "verifier bug: helper %s#%d is not marked as callback-calling\n", + func_id_name(insn->imm), insn->imm); + return -EFAULT; + } + if (insn->code == (BPF_JMP | BPF_CALL) && insn->src_reg == 0 && insn->imm == BPF_FUNC_timer_set_callback) { @@ -14571,6 +14629,8 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) BPF_MAIN_FUNC /* callsite */, 0 /* frameno */, subprog); + state->first_insn_idx = env->subprog_info[subprog].start; + state->last_insn_idx = -1; regs = state->frame[state->curframe]->regs; if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) { |