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bpf: Refactor verifier dynptr into get_dynptr_arg_reg 

This commit refactors the logic for determining which register in a
function is the dynptr into "get_dynptr_arg_reg". This will be used
in the future when the dynptr reg for BPF_FUNC_dynptr_write will need
to be obtained in order to support writes for skb dynptrs.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://lore.kernel.org/r/20230301154953.641654-6-joannelkoong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Joanne Koong 2023-03-01 07:49:48 -08:00 committed by Alexei Starovoitov
parent 8357b366cb
commit 485ec51ef9
1 changed files with 51 additions and 31 deletions
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82
kernel/bpf/verifier.c
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@ -6689,6 +6689,28 @@ int check_func_arg_reg_off(struct bpf_verifier_env *env,
}
}
static struct bpf_reg_state *get_dynptr_arg_reg(struct bpf_verifier_env *env,
const struct bpf_func_proto *fn,
struct bpf_reg_state *regs)
{
struct bpf_reg_state *state = NULL;
int i;
for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)
if (arg_type_is_dynptr(fn->arg_type[i])) {
if (state) {
verbose(env, "verifier internal error: multiple dynptr args\n");
return NULL;
}
state = &regs[BPF_REG_1 + i];
}
if (!state)
verbose(env, "verifier internal error: no dynptr arg found\n");
return state;
}
static int dynptr_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
struct bpf_func_state *state = func(env, reg);
@ -8326,43 +8348,41 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
}
break;
case BPF_FUNC_dynptr_data:
for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
if (arg_type_is_dynptr(fn->arg_type[i])) {
struct bpf_reg_state *reg = &regs[BPF_REG_1 + i];
int id, ref_obj_id;
{
struct bpf_reg_state *reg;
int id, ref_obj_id;
if (meta.dynptr_id) {
verbose(env, "verifier internal error: meta.dynptr_id already set\n");
return -EFAULT;
}
reg = get_dynptr_arg_reg(env, fn, regs);
if (!reg)
return -EFAULT;
if (meta.ref_obj_id) {
verbose(env, "verifier internal error: meta.ref_obj_id already set\n");
return -EFAULT;
}
id = dynptr_id(env, reg);
if (id < 0) {
verbose(env, "verifier internal error: failed to obtain dynptr id\n");
return id;
}
ref_obj_id = dynptr_ref_obj_id(env, reg);
if (ref_obj_id < 0) {
verbose(env, "verifier internal error: failed to obtain dynptr ref_obj_id\n");
return ref_obj_id;
}
meta.dynptr_id = id;
meta.ref_obj_id = ref_obj_id;
break;
}
}
if (i == MAX_BPF_FUNC_REG_ARGS) {
verbose(env, "verifier internal error: no dynptr in bpf_dynptr_data()\n");
if (meta.dynptr_id) {
verbose(env, "verifier internal error: meta.dynptr_id already set\n");
return -EFAULT;
}
if (meta.ref_obj_id) {
verbose(env, "verifier internal error: meta.ref_obj_id already set\n");
return -EFAULT;
}
id = dynptr_id(env, reg);
if (id < 0) {
verbose(env, "verifier internal error: failed to obtain dynptr id\n");
return id;
}
ref_obj_id = dynptr_ref_obj_id(env, reg);
if (ref_obj_id < 0) {
verbose(env, "verifier internal error: failed to obtain dynptr ref_obj_id\n");
return ref_obj_id;
}
meta.dynptr_id = id;
meta.ref_obj_id = ref_obj_id;
break;
}
case BPF_FUNC_user_ringbuf_drain:
err = __check_func_call(env, insn, insn_idx_p, meta.subprogno,
set_user_ringbuf_callback_state);