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bpf: track references based on is_acquire_func 

So far, the verifier only acquires reference tracking state for
RET_PTR_TO_SOCKET_OR_NULL. Instead of extending this for every
new return type which desires these semantics, acquire reference
tracking state iff the called helper is an acquire function.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Lorenz Bauer 2019-03-22 09:53:59 +08:00 committed by Alexei Starovoitov
parent 48e5d98a0e
commit 0f3adc288d
1 changed files with 12 additions and 14 deletions
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26
kernel/bpf/verifier.c
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@ -3147,19 +3147,7 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
} else if (fn->ret_type == RET_PTR_TO_SOCKET_OR_NULL) {
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_SOCKET_OR_NULL;
if (is_acquire_function(func_id)) {
int id = acquire_reference_state(env, insn_idx);
if (id < 0)
return id;
/* For mark_ptr_or_null_reg() */
regs[BPF_REG_0].id = id;
/* For release_reference() */
regs[BPF_REG_0].ref_obj_id = id;
} else {
/* For mark_ptr_or_null_reg() */
regs[BPF_REG_0].id = ++env->id_gen;
}
regs[BPF_REG_0].id = ++env->id_gen;
} else if (fn->ret_type == RET_PTR_TO_TCP_SOCK_OR_NULL) {
mark_reg_known_zero(env, regs, BPF_REG_0);
regs[BPF_REG_0].type = PTR_TO_TCP_SOCK_OR_NULL;
@ -3170,9 +3158,19 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
return -EINVAL;
}
if (is_ptr_cast_function(func_id))
if (is_ptr_cast_function(func_id)) {
/* For release_reference() */
regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
} else if (is_acquire_function(func_id)) {
int id = acquire_reference_state(env, insn_idx);
if (id < 0)
return id;
/* For mark_ptr_or_null_reg() */
regs[BPF_REG_0].id = id;
/* For release_reference() */
regs[BPF_REG_0].ref_obj_id = id;
}
do_refine_retval_range(regs, fn->ret_type, func_id, &meta);