diff options
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 32 |
1 files changed, 29 insertions, 3 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 800488289297..bc24bdadc193 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4943,6 +4943,25 @@ static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val) return 0; } +#define BTF_TYPE_SAFE_NESTED(__type) __PASTE(__type, __safe_fields) + +BTF_TYPE_SAFE_NESTED(struct task_struct) { + const cpumask_t *cpus_ptr; +}; + +static bool nested_ptr_is_trusted(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + int off) +{ + /* If its parent is not trusted, it can't regain its trusted status. */ + if (!is_trusted_reg(reg)) + return false; + + BTF_TYPE_EMIT(BTF_TYPE_SAFE_NESTED(struct task_struct)); + + return btf_nested_type_is_trusted(&env->log, reg, off); +} + static int check_ptr_to_btf_access(struct bpf_verifier_env *env, struct bpf_reg_state *regs, int regno, int off, int size, @@ -5031,10 +5050,17 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env, if (type_flag(reg->type) & PTR_UNTRUSTED) flag |= PTR_UNTRUSTED; - /* By default any pointer obtained from walking a trusted pointer is - * no longer trusted except the rcu case below. + /* By default any pointer obtained from walking a trusted pointer is no + * longer trusted, unless the field being accessed has explicitly been + * marked as inheriting its parent's state of trust. + * + * An RCU-protected pointer can also be deemed trusted if we are in an + * RCU read region. This case is handled below. */ - flag &= ~PTR_TRUSTED; + if (nested_ptr_is_trusted(env, reg, off)) + flag |= PTR_TRUSTED; + else + flag &= ~PTR_TRUSTED; if (flag & MEM_RCU) { /* Mark value register as MEM_RCU only if it is protected by |