[RFC PATCH v5 mm-new 4/5] bpf: mark vma->vm_mm as trusted

[Yafang Shao <laoar.shao@gmail.com>]

Every VMA must have an associated mm_struct, and it is safe to access
outside of RCU. Thus, we can mark it as trusted. With this change, BPF
helpers can safely access vma->vm_mm to retrieve the associated task
from the VMA.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 kernel/bpf/verifier.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index c4f69a9e9af6..984ffbca5cbe 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7154,6 +7154,10 @@ BTF_TYPE_SAFE_TRUSTED(struct file) {
 	struct inode *f_inode;
 };
 
+BTF_TYPE_SAFE_TRUSTED(struct vm_area_struct) {
+	struct mm_struct *vm_mm;
+};
+
 BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry) {
 	struct inode *d_inode;
 };
@@ -7193,6 +7197,7 @@ static bool type_is_trusted(struct bpf_verifier_env *env,
 	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task));
 	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct linux_binprm));
 	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct file));
+	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct vm_area_struct));
 
 	return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted");
 }
-- 
2.47.3