mirror of
https://github.com/torvalds/linux
synced 2024-10-15 15:59:15 +00:00
bpf: move subprog call logic back to verifier.c
Subprog call logic in btf_check_subprog_call() currently has both a lot of BTF parsing logic (which is, presumably, what justified putting it into btf.c), but also a bunch of register state checks, some of each utilize deep verifier logic helpers, necessarily exported from verifier.c: check_ptr_off_reg(), check_func_arg_reg_off(), and check_mem_reg(). Going forward, btf_check_subprog_call() will have a minimum of BTF-related logic, but will get more internal verifier logic related to register state manipulation. So move it into verifier.c to minimize amount of verifier-specific logic exposed to btf.c. We do this move before refactoring btf_check_func_arg_match() to preserve as much history post-refactoring as possible. No functional changes. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko
Alexei Starovoitov
parent
e26080d0da
commit
c5a7244759
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@ -2466,8 +2466,6 @@ int btf_distill_func_proto(struct bpf_verifier_log *log,
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struct btf_func_model *m);
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struct bpf_reg_state;
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int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
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struct bpf_reg_state *regs);
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int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog);
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int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog,
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struct btf *btf, const struct btf_type *t);
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@ -785,14 +785,6 @@ bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off,
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void
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bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt);
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int check_ptr_off_reg(struct bpf_verifier_env *env,
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const struct bpf_reg_state *reg, int regno);
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int check_func_arg_reg_off(struct bpf_verifier_env *env,
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const struct bpf_reg_state *reg, int regno,
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enum bpf_arg_type arg_type);
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int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
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u32 regno, u32 mem_size);
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/* this lives here instead of in bpf.h because it needs to dereference tgt_prog */
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static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog,
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struct btf *btf, u32 btf_id)
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139
kernel/bpf/btf.c
139
kernel/bpf/btf.c
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@ -6765,145 +6765,6 @@ int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *pr
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return btf_check_func_type_match(log, btf1, t1, btf2, t2);
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}
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static int btf_check_func_arg_match(struct bpf_verifier_env *env,
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const struct btf *btf, u32 func_id,
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struct bpf_reg_state *regs,
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bool ptr_to_mem_ok)
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{
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enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
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struct bpf_verifier_log *log = &env->log;
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const char *func_name, *ref_tname;
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const struct btf_type *t, *ref_t;
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const struct btf_param *args;
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u32 i, nargs, ref_id;
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int ret;
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t = btf_type_by_id(btf, func_id);
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if (!t || !btf_type_is_func(t)) {
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/* These checks were already done by the verifier while loading
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* struct bpf_func_info or in add_kfunc_call().
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*/
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bpf_log(log, "BTF of func_id %u doesn't point to KIND_FUNC\n",
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func_id);
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return -EFAULT;
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}
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func_name = btf_name_by_offset(btf, t->name_off);
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t = btf_type_by_id(btf, t->type);
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if (!t || !btf_type_is_func_proto(t)) {
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bpf_log(log, "Invalid BTF of func %s\n", func_name);
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return -EFAULT;
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}
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args = (const struct btf_param *)(t + 1);
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nargs = btf_type_vlen(t);
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if (nargs > MAX_BPF_FUNC_REG_ARGS) {
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bpf_log(log, "Function %s has %d > %d args\n", func_name, nargs,
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MAX_BPF_FUNC_REG_ARGS);
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return -EINVAL;
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}
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/* check that BTF function arguments match actual types that the
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* verifier sees.
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*/
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for (i = 0; i < nargs; i++) {
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enum bpf_arg_type arg_type = ARG_DONTCARE;
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u32 regno = i + 1;
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struct bpf_reg_state *reg = ®s[regno];
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t = btf_type_skip_modifiers(btf, args[i].type, NULL);
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if (btf_type_is_scalar(t)) {
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if (reg->type == SCALAR_VALUE)
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continue;
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bpf_log(log, "R%d is not a scalar\n", regno);
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return -EINVAL;
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}
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if (!btf_type_is_ptr(t)) {
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bpf_log(log, "Unrecognized arg#%d type %s\n",
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i, btf_type_str(t));
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return -EINVAL;
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}
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ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
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ref_tname = btf_name_by_offset(btf, ref_t->name_off);
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ret = check_func_arg_reg_off(env, reg, regno, arg_type);
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if (ret < 0)
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return ret;
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if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
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/* If function expects ctx type in BTF check that caller
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* is passing PTR_TO_CTX.
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*/
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if (reg->type != PTR_TO_CTX) {
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bpf_log(log,
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"arg#%d expected pointer to ctx, but got %s\n",
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i, btf_type_str(t));
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return -EINVAL;
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}
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} else if (ptr_to_mem_ok) {
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const struct btf_type *resolve_ret;
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u32 type_size;
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resolve_ret = btf_resolve_size(btf, ref_t, &type_size);
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if (IS_ERR(resolve_ret)) {
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bpf_log(log,
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"arg#%d reference type('%s %s') size cannot be determined: %ld\n",
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i, btf_type_str(ref_t), ref_tname,
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PTR_ERR(resolve_ret));
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return -EINVAL;
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}
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if (check_mem_reg(env, reg, regno, type_size))
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return -EINVAL;
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} else {
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bpf_log(log, "reg type unsupported for arg#%d function %s#%d\n", i,
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func_name, func_id);
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return -EINVAL;
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}
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}
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return 0;
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}
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/* Compare BTF of a function call with given bpf_reg_state.
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* Returns:
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* EFAULT - there is a verifier bug. Abort verification.
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* EINVAL - there is a type mismatch or BTF is not available.
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* 0 - BTF matches with what bpf_reg_state expects.
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* Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
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*/
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int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
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struct bpf_reg_state *regs)
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{
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struct bpf_prog *prog = env->prog;
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struct btf *btf = prog->aux->btf;
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bool is_global;
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u32 btf_id;
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int err;
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if (!prog->aux->func_info)
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return -EINVAL;
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btf_id = prog->aux->func_info[subprog].type_id;
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if (!btf_id)
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return -EFAULT;
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if (prog->aux->func_info_aux[subprog].unreliable)
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return -EINVAL;
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is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL;
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err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global);
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/* Compiler optimizations can remove arguments from static functions
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* or mismatched type can be passed into a global function.
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* In such cases mark the function as unreliable from BTF point of view.
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*/
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if (err)
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prog->aux->func_info_aux[subprog].unreliable = true;
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return err;
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}
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/* Process BTF of a function to produce high-level expectation of function
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* arguments (like ARG_PTR_TO_CTX, or ARG_PTR_TO_MEM, etc). This information
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* is cached in subprog info for reuse.
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@ -5127,8 +5127,8 @@ static int __check_ptr_off_reg(struct bpf_verifier_env *env,
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return 0;
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}
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int check_ptr_off_reg(struct bpf_verifier_env *env,
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const struct bpf_reg_state *reg, int regno)
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static int check_ptr_off_reg(struct bpf_verifier_env *env,
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const struct bpf_reg_state *reg, int regno)
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{
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return __check_ptr_off_reg(env, reg, regno, false);
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}
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@ -7300,8 +7300,8 @@ static int check_mem_size_reg(struct bpf_verifier_env *env,
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return err;
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}
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int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
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u32 regno, u32 mem_size)
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static int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
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u32 regno, u32 mem_size)
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{
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bool may_be_null = type_may_be_null(reg->type);
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struct bpf_reg_state saved_reg;
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@ -8286,9 +8286,9 @@ reg_find_field_offset(const struct bpf_reg_state *reg, s32 off, u32 fields)
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return field;
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}
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int check_func_arg_reg_off(struct bpf_verifier_env *env,
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const struct bpf_reg_state *reg, int regno,
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enum bpf_arg_type arg_type)
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static int check_func_arg_reg_off(struct bpf_verifier_env *env,
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const struct bpf_reg_state *reg, int regno,
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enum bpf_arg_type arg_type)
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{
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u32 type = reg->type;
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@ -9249,6 +9249,145 @@ static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int calls
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return err;
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}
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static int btf_check_func_arg_match(struct bpf_verifier_env *env,
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const struct btf *btf, u32 func_id,
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struct bpf_reg_state *regs,
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bool ptr_to_mem_ok)
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{
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enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
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struct bpf_verifier_log *log = &env->log;
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const char *func_name, *ref_tname;
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const struct btf_type *t, *ref_t;
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const struct btf_param *args;
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u32 i, nargs, ref_id;
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int ret;
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t = btf_type_by_id(btf, func_id);
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if (!t || !btf_type_is_func(t)) {
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/* These checks were already done by the verifier while loading
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* struct bpf_func_info or in add_kfunc_call().
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*/
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bpf_log(log, "BTF of func_id %u doesn't point to KIND_FUNC\n",
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func_id);
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return -EFAULT;
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}
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func_name = btf_name_by_offset(btf, t->name_off);
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t = btf_type_by_id(btf, t->type);
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if (!t || !btf_type_is_func_proto(t)) {
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bpf_log(log, "Invalid BTF of func %s\n", func_name);
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return -EFAULT;
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}
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args = (const struct btf_param *)(t + 1);
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nargs = btf_type_vlen(t);
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if (nargs > MAX_BPF_FUNC_REG_ARGS) {
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bpf_log(log, "Function %s has %d > %d args\n", func_name, nargs,
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MAX_BPF_FUNC_REG_ARGS);
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return -EINVAL;
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}
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/* check that BTF function arguments match actual types that the
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* verifier sees.
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*/
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for (i = 0; i < nargs; i++) {
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enum bpf_arg_type arg_type = ARG_DONTCARE;
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u32 regno = i + 1;
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struct bpf_reg_state *reg = ®s[regno];
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t = btf_type_skip_modifiers(btf, args[i].type, NULL);
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if (btf_type_is_scalar(t)) {
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if (reg->type == SCALAR_VALUE)
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continue;
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bpf_log(log, "R%d is not a scalar\n", regno);
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return -EINVAL;
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}
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if (!btf_type_is_ptr(t)) {
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bpf_log(log, "Unrecognized arg#%d type %s\n",
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i, btf_type_str(t));
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return -EINVAL;
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}
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ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
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ref_tname = btf_name_by_offset(btf, ref_t->name_off);
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ret = check_func_arg_reg_off(env, reg, regno, arg_type);
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if (ret < 0)
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return ret;
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if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
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/* If function expects ctx type in BTF check that caller
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* is passing PTR_TO_CTX.
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*/
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if (reg->type != PTR_TO_CTX) {
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bpf_log(log,
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"arg#%d expected pointer to ctx, but got %s\n",
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i, btf_type_str(t));
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return -EINVAL;
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}
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} else if (ptr_to_mem_ok) {
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const struct btf_type *resolve_ret;
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u32 type_size;
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resolve_ret = btf_resolve_size(btf, ref_t, &type_size);
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if (IS_ERR(resolve_ret)) {
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bpf_log(log,
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"arg#%d reference type('%s %s') size cannot be determined: %ld\n",
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i, btf_type_str(ref_t), ref_tname,
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PTR_ERR(resolve_ret));
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return -EINVAL;
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}
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if (check_mem_reg(env, reg, regno, type_size))
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return -EINVAL;
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} else {
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bpf_log(log, "reg type unsupported for arg#%d function %s#%d\n", i,
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func_name, func_id);
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return -EINVAL;
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}
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}
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return 0;
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}
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/* Compare BTF of a function call with given bpf_reg_state.
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* Returns:
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* EFAULT - there is a verifier bug. Abort verification.
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* EINVAL - there is a type mismatch or BTF is not available.
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* 0 - BTF matches with what bpf_reg_state expects.
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* Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
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*/
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static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
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struct bpf_reg_state *regs)
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{
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struct bpf_prog *prog = env->prog;
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struct btf *btf = prog->aux->btf;
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bool is_global;
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u32 btf_id;
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int err;
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if (!prog->aux->func_info)
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return -EINVAL;
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btf_id = prog->aux->func_info[subprog].type_id;
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if (!btf_id)
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return -EFAULT;
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if (prog->aux->func_info_aux[subprog].unreliable)
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return -EINVAL;
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is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL;
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err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global);
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/* Compiler optimizations can remove arguments from static functions
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* or mismatched type can be passed into a global function.
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* In such cases mark the function as unreliable from BTF point of view.
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*/
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if (err)
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prog->aux->func_info_aux[subprog].unreliable = true;
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return err;
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}
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static int push_callback_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
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int insn_idx, int subprog,
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set_callee_state_fn set_callee_state_cb)
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