diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 4e7d671497f4..fd90ba498ccc 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5378,6 +5378,7 @@ static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val) } #define BTF_TYPE_SAFE_RCU(__type) __PASTE(__type, __safe_rcu) +#define BTF_TYPE_SAFE_RCU_OR_NULL(__type) __PASTE(__type, __safe_rcu_or_null) #define BTF_TYPE_SAFE_TRUSTED(__type) __PASTE(__type, __safe_trusted) /* @@ -5394,10 +5395,31 @@ BTF_TYPE_SAFE_RCU(struct task_struct) { struct task_struct *group_leader; }; +BTF_TYPE_SAFE_RCU(struct cgroup) { + /* cgrp->kn is always accessible as documented in kernel/cgroup/cgroup.c */ + struct kernfs_node *kn; +}; + BTF_TYPE_SAFE_RCU(struct css_set) { struct cgroup *dfl_cgrp; }; +/* RCU trusted: these fields are trusted in RCU CS and can be NULL */ +BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct) { + struct file __rcu *exe_file; +}; + +/* skb->sk, req->sk are not RCU protected, but we mark them as such + * because bpf prog accessible sockets are SOCK_RCU_FREE. + */ +BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff) { + struct sock *sk; +}; + +BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock) { + struct sock *sk; +}; + /* full trusted: these fields are trusted even outside of RCU CS and never NULL */ BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta) { struct seq_file *seq; @@ -5430,11 +5452,23 @@ static bool type_is_rcu(struct bpf_verifier_env *env, const char *field_name, u32 btf_id) { BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct task_struct)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct cgroup)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct css_set)); return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu"); } +static bool type_is_rcu_or_null(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + const char *field_name, u32 btf_id) +{ + BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock)); + + return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu_or_null"); +} + static bool type_is_trusted(struct bpf_verifier_env *env, struct bpf_reg_state *reg, const char *field_name, u32 btf_id) @@ -5561,9 +5595,10 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env, if (type_is_rcu(env, reg, field_name, btf_id)) { /* ignore __rcu tag and mark it MEM_RCU */ flag |= MEM_RCU; - } else if (flag & MEM_RCU) { + } else if (flag & MEM_RCU || + type_is_rcu_or_null(env, reg, field_name, btf_id)) { /* __rcu tagged pointers can be NULL */ - flag |= PTR_MAYBE_NULL; + flag |= MEM_RCU | PTR_MAYBE_NULL; } else if (flag & (MEM_PERCPU | MEM_USER)) { /* keep as-is */ } else {