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bpf: Refactor check_pseudo_btf_id

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Introduce a helper to add btfs to the env->used_maps array. Use it
to simplify the check_pseudo_btf_id() function. This new helper will
also be re-used in a consequent patch.

Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241213130934.1087929-4-aspsk@isovalent.com
This commit is contained in:
Anton Protopopov 2024-12-13 13:09:30 +00:00 • committed by Andrii Nakryiko
parent 928f3221cb
commit 76145f7255
1 changed files with 82 additions and 62 deletions
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144
kernel/bpf/verifier.c
View file

@ -19218,50 +19218,68 @@ static int find_btf_percpu_datasec(struct btf *btf)
return -ENOENT;
}
/*
* Add btf to the used_btfs array and return the index. (If the btf was
* already added, then just return the index.) Upon successful insertion
* increase btf refcnt, and, if present, also refcount the corresponding
* kernel module.
*/
static int __add_used_btf(struct bpf_verifier_env *env, struct btf *btf)
{
struct btf_mod_pair *btf_mod;
int i;
/* check whether we recorded this BTF (and maybe module) already */
for (i = 0; i < env->used_btf_cnt; i++)
if (env->used_btfs[i].btf == btf)
return i;
if (env->used_btf_cnt >= MAX_USED_BTFS)
return -E2BIG;
btf_get(btf);
btf_mod = &env->used_btfs[env->used_btf_cnt];
btf_mod->btf = btf;
btf_mod->module = NULL;
/* if we reference variables from kernel module, bump its refcount */
if (btf_is_module(btf)) {
btf_mod->module = btf_try_get_module(btf);
if (!btf_mod->module) {
btf_put(btf);
return -ENXIO;
}
}
return env->used_btf_cnt++;
}
/* replace pseudo btf_id with kernel symbol address */
static int check_pseudo_btf_id(struct bpf_verifier_env *env,
struct bpf_insn *insn,
struct bpf_insn_aux_data *aux)
static int __check_pseudo_btf_id(struct bpf_verifier_env *env,
struct bpf_insn *insn,
struct bpf_insn_aux_data *aux,
struct btf *btf)
{
const struct btf_var_secinfo *vsi;
const struct btf_type *datasec;
struct btf_mod_pair *btf_mod;
const struct btf_type *t;
const char *sym_name;
bool percpu = false;
u32 type, id = insn->imm;
struct btf *btf;
s32 datasec_id;
u64 addr;
int i, btf_fd, err;
btf_fd = insn[1].imm;
if (btf_fd) {
btf = btf_get_by_fd(btf_fd);
if (IS_ERR(btf)) {
verbose(env, "invalid module BTF object FD specified.\n");
return -EINVAL;
}
} else {
if (!btf_vmlinux) {
verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n");
return -EINVAL;
}
btf = btf_vmlinux;
btf_get(btf);
}
int i;
t = btf_type_by_id(btf, id);
if (!t) {
verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id);
err = -ENOENT;
goto err_put;
return -ENOENT;
}
if (!btf_type_is_var(t) && !btf_type_is_func(t)) {
verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR or KIND_FUNC\n", id);
err = -EINVAL;
goto err_put;
return -EINVAL;
}
sym_name = btf_name_by_offset(btf, t->name_off);
@ -19269,8 +19287,7 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,
if (!addr) {
verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n",
sym_name);
err = -ENOENT;
goto err_put;
return -ENOENT;
}
insn[0].imm = (u32)addr;
insn[1].imm = addr >> 32;
@ -19278,7 +19295,7 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,
if (btf_type_is_func(t)) {
aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
aux->btf_var.mem_size = 0;
goto check_btf;
return 0;
}
datasec_id = find_btf_percpu_datasec(btf);
@ -19309,8 +19326,7 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,
tname = btf_name_by_offset(btf, t->name_off);
verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n",
tname, PTR_ERR(ret));
err = -EINVAL;
goto err_put;
return -EINVAL;
}
aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
aux->btf_var.mem_size = tsize;
@ -19319,39 +19335,43 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,
aux->btf_var.btf = btf;
aux->btf_var.btf_id = type;
}
check_btf:
/* check whether we recorded this BTF (and maybe module) already */
for (i = 0; i < env->used_btf_cnt; i++) {
if (env->used_btfs[i].btf == btf) {
btf_put(btf);
return 0;
}
}
if (env->used_btf_cnt >= MAX_USED_BTFS) {
err = -E2BIG;
goto err_put;
}
btf_mod = &env->used_btfs[env->used_btf_cnt];
btf_mod->btf = btf;
btf_mod->module = NULL;
/* if we reference variables from kernel module, bump its refcount */
if (btf_is_module(btf)) {
btf_mod->module = btf_try_get_module(btf);
if (!btf_mod->module) {
err = -ENXIO;
goto err_put;
}
}
env->used_btf_cnt++;
return 0;
err_put:
btf_put(btf);
return err;
}
static int check_pseudo_btf_id(struct bpf_verifier_env *env,
struct bpf_insn *insn,
struct bpf_insn_aux_data *aux)
{
struct btf *btf;
int btf_fd;
int err;
btf_fd = insn[1].imm;
if (btf_fd) {
CLASS(fd, f)(btf_fd);
btf = __btf_get_by_fd(f);
if (IS_ERR(btf)) {
verbose(env, "invalid module BTF object FD specified.\n");
return -EINVAL;
}
} else {
if (!btf_vmlinux) {
verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n");
return -EINVAL;
}
btf = btf_vmlinux;
}
err = __check_pseudo_btf_id(env, insn, aux, btf);
if (err)
return err;
err = __add_used_btf(env, btf);
if (err < 0)
return err;
return 0;
}
static bool is_tracing_prog_type(enum bpf_prog_type type)