问题描述
正如LDD3第6页p175所示，我们可以通过current->uid和current->euid获得当前进程的UID和EUID.但是Linux Kernel 4.2的struct task_struct定义不再包含uid或euid命名的字段.因此，我想知道是否还有其他获取UID和EUID的方法?谢谢！
As LDD3 chapter 6 p175 show, we can get current process UID and EUID by current->uid and current->euid.But the definition of struct task_struct of Linux Kernel 4.2 don't contain fields named by uid or euid any more.So, I wonder if there are any other methods to get UID and EUID ?Thanks!
推荐答案
.uid和.euid字段已移至struct cred，现在在struct task_struct中显示为.cred字段.它是在以下提交中完成的: CRED :将任务安全性上下文与task_struct 分开.如果查看include/linux/sched.h文件的差异，您会注意到这一变化:
.uid and .euid fields were moved to struct cred, which is now exposed as .cred field in struct task_struct. It was done in this commit: CRED: Separate task security context from task_struct. If you look at diff for include/linux/sched.h file, you can notice this change:
- uid_t uid,euid,suid,fsuid;
- gid_t gid,egid,sgid,fsgid;
+ struct cred *cred; /* actual/objective task credentials */
所以现在代替:
current->uid;
current->euid;
您应该使用:
const struct cred *cred = current_cred();
cred->uid;
cred->euid;
请注意，应该使用current_cred()函数来访问.cred字段，因为它是 RCU 指针.
Notice that current_cred() function should be used to access .cred field, as it's RCU pointer.
还要 check_same_owner()实现例子.
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