diff options
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 113 |
1 files changed, 103 insertions, 10 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d6a4102312fa..756e179a1efe 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2636,16 +2636,36 @@ static int cmp_subprogs(const void *a, const void *b) ((struct bpf_subprog_info *)b)->start; } +/* Find subprogram that contains instruction at 'off' */ +static struct bpf_subprog_info *find_containing_subprog(struct bpf_verifier_env *env, int off) +{ + struct bpf_subprog_info *vals = env->subprog_info; + int l, r, m; + + if (off >= env->prog->len || off < 0 || env->subprog_cnt == 0) + return NULL; + + l = 0; + r = env->subprog_cnt - 1; + while (l < r) { + m = l + (r - l + 1) / 2; + if (vals[m].start <= off) + l = m; + else + r = m - 1; + } + return &vals[l]; +} + +/* Find subprogram that starts exactly at 'off' */ static int find_subprog(struct bpf_verifier_env *env, int off) { struct bpf_subprog_info *p; - p = bsearch(&off, env->subprog_info, env->subprog_cnt, - sizeof(env->subprog_info[0]), cmp_subprogs); - if (!p) + p = find_containing_subprog(env, off); + if (!p || p->start != off) return -ENOENT; return p - env->subprog_info; - } static int add_subprog(struct bpf_verifier_env *env, int off) @@ -9344,6 +9364,8 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, if (env->log.level & BPF_LOG_LEVEL) verbose(env, "Func#%d is global and valid. Skipping.\n", subprog); + if (env->subprog_info[subprog].changes_pkt_data) + clear_all_pkt_pointers(env); clear_caller_saved_regs(env, caller->regs); /* All global functions return a 64-bit SCALAR_VALUE */ @@ -9987,7 +10009,7 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn } /* With LD_ABS/IND some JITs save/restore skb from r1. */ - changes_data = bpf_helper_changes_pkt_data(fn->func); + changes_data = bpf_helper_changes_pkt_data(func_id); if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) { verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n", func_id_name(func_id), func_id); @@ -15094,6 +15116,29 @@ static int check_return_code(struct bpf_verifier_env *env) return 0; } +static void mark_subprog_changes_pkt_data(struct bpf_verifier_env *env, int off) +{ + struct bpf_subprog_info *subprog; + + subprog = find_containing_subprog(env, off); + subprog->changes_pkt_data = true; +} + +/* 't' is an index of a call-site. + * 'w' is a callee entry point. + * Eventually this function would be called when env->cfg.insn_state[w] == EXPLORED. + * Rely on DFS traversal order and absence of recursive calls to guarantee that + * callee's change_pkt_data marks would be correct at that moment. + */ +static void merge_callee_effects(struct bpf_verifier_env *env, int t, int w) +{ + struct bpf_subprog_info *caller, *callee; + + caller = find_containing_subprog(env, t); + callee = find_containing_subprog(env, w); + caller->changes_pkt_data |= callee->changes_pkt_data; +} + /* non-recursive DFS pseudo code * 1 procedure DFS-iterative(G,v): * 2 label v as discovered @@ -15227,6 +15272,7 @@ static int visit_func_call_insn(int t, struct bpf_insn *insns, bool visit_callee) { int ret, insn_sz; + int w; insn_sz = bpf_is_ldimm64(&insns[t]) ? 2 : 1; ret = push_insn(t, t + insn_sz, FALLTHROUGH, env); @@ -15238,8 +15284,10 @@ static int visit_func_call_insn(int t, struct bpf_insn *insns, mark_jmp_point(env, t + insn_sz); if (visit_callee) { + w = t + insns[t].imm + 1; mark_prune_point(env, t); - ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env); + merge_callee_effects(env, t, w); + ret = push_insn(t, w, BRANCH, env); } return ret; } @@ -15291,6 +15339,8 @@ static int visit_insn(int t, struct bpf_verifier_env *env) mark_prune_point(env, t); mark_jmp_point(env, t); } + if (bpf_helper_call(insn) && bpf_helper_changes_pkt_data(insn->imm)) + mark_subprog_changes_pkt_data(env, t); if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { struct bpf_kfunc_call_arg_meta meta; @@ -15412,6 +15462,7 @@ static int check_cfg(struct bpf_verifier_env *env) } } ret = 0; /* cfg looks good */ + env->prog->aux->changes_pkt_data = env->subprog_info[0].changes_pkt_data; err_free: kvfree(insn_state); @@ -18572,6 +18623,7 @@ static int jit_subprogs(struct bpf_verifier_env *env) } func[i]->aux->num_exentries = num_exentries; func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable; + func[i]->aux->changes_pkt_data = env->subprog_info[i].changes_pkt_data; func[i] = bpf_int_jit_compile(func[i]); if (!func[i]->jited) { err = -ENOTSUPP; @@ -19856,6 +19908,7 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, } if (tgt_prog) { struct bpf_prog_aux *aux = tgt_prog->aux; + bool tgt_changes_pkt_data; if (bpf_prog_is_dev_bound(prog->aux) && !bpf_prog_dev_bound_match(prog, tgt_prog)) { @@ -19884,6 +19937,14 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, "Extension programs should be JITed\n"); return -EINVAL; } + tgt_changes_pkt_data = aux->func + ? aux->func[subprog]->aux->changes_pkt_data + : aux->changes_pkt_data; + if (prog->aux->changes_pkt_data && !tgt_changes_pkt_data) { + bpf_log(log, + "Extension program changes packet data, while original does not\n"); + return -EINVAL; + } } if (!tgt_prog->jited) { bpf_log(log, "Can attach to only JITed progs\n"); @@ -20106,6 +20167,33 @@ BTF_ID(func, __rcu_read_unlock) #endif BTF_SET_END(btf_id_deny) +/* fexit and fmod_ret can't be used to attach to __noreturn functions. + * Currently, we must manually list all __noreturn functions here. Once a more + * robust solution is implemented, this workaround can be removed. + */ +BTF_SET_START(noreturn_deny) +#ifdef CONFIG_IA32_EMULATION +BTF_ID(func, __ia32_sys_exit) +BTF_ID(func, __ia32_sys_exit_group) +#endif +#ifdef CONFIG_KUNIT +BTF_ID(func, __kunit_abort) +BTF_ID(func, kunit_try_catch_throw) +#endif +#ifdef CONFIG_MODULES +BTF_ID(func, __module_put_and_kthread_exit) +#endif +#ifdef CONFIG_X86_64 +BTF_ID(func, __x64_sys_exit) +BTF_ID(func, __x64_sys_exit_group) +#endif +BTF_ID(func, do_exit) +BTF_ID(func, do_group_exit) +BTF_ID(func, kthread_complete_and_exit) +BTF_ID(func, kthread_exit) +BTF_ID(func, make_task_dead) +BTF_SET_END(noreturn_deny) + static bool can_be_sleepable(struct bpf_prog *prog) { if (prog->type == BPF_PROG_TYPE_TRACING) { @@ -20194,6 +20282,11 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) } else if (prog->type == BPF_PROG_TYPE_TRACING && btf_id_set_contains(&btf_id_deny, btf_id)) { return -EINVAL; + } else if ((prog->expected_attach_type == BPF_TRACE_FEXIT || + prog->expected_attach_type == BPF_MODIFY_RETURN) && + btf_id_set_contains(&noreturn_deny, btf_id)) { + verbose(env, "Attaching fexit/fmod_ret to __noreturn functions is rejected.\n"); + return -EINVAL; } key = bpf_trampoline_compute_key(tgt_prog, prog->aux->attach_btf, btf_id); @@ -20311,10 +20404,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 if (ret < 0) goto skip_full_check; - ret = check_attach_btf_id(env); - if (ret) - goto skip_full_check; - ret = resolve_pseudo_ldimm64(env); if (ret < 0) goto skip_full_check; @@ -20329,6 +20418,10 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 if (ret < 0) goto skip_full_check; + ret = check_attach_btf_id(env); + if (ret) + goto skip_full_check; + ret = do_check_subprogs(env); ret = ret ?: do_check_main(env); |