LSM在Linux中的實現方式

LSM(Linux Secure Model)一種輕量級訪問控制機制.

其實現方式有如在系統調用中加入一個後門....

方式如下:

static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
     struct file *f,
     int (*open)(struct inode *, struct file *),
     const struct cred *cred)
{
 struct inode *inode;
 int error;

 ...............................................................

 error = security_dentry_open(f, cred);   //LSM機制實現方式,在此加入了一個LSM函數.

                                                                      //security_dentry_open的實現如下,相當於一個接口,對一個函數指針再

                                                                     //封裝一下.

                                                                     //只返回是與否,這樣的控制信息.
 if (error)
  goto cleanup_all;

 ................................................................

 return f;

cleanup_all:
 .................................................................
 return ERR_PTR(error);
}
//========簡單封裝一個指針結構體===========================

int security_dentry_open(struct file *file, const struct cred *cred)
{
 int ret;

 ret = security_ops->dentry_open(file, cred);
 if (ret)
  return ret;

 return fsnotify_perm(file, MAY_OPEN);
}