Attention: Uses for to appraise point inode. This meaning is you may use one pair to obtain in a system unique inode.
In /ur/src/Linux/cinclude/Linux/dcache.h
struct dentry {
int d_count;
unsigned int d_flags;
struct inode * d_inode; /* Where the name belongs to - NULL is negative */
struct dentry * d_parent; /* parent directory */
struct dentry * d_mounts; /* mount information */
struct dentry * d_covers;
struct list_head d_hash; /* lookup hash list */
struct list_head d_lru; /* d_count = 0 LRU list */
struct list_head d_child; /* child of parent list */
struct list_head d_subdirs; /* our
......
}
dentry is a directory file entrance. Through this entrance, we may very easy move under the document father table of contents.
For example, if your document's inode is (struct inode*) file_inode, if you may use file_inode->d_entry to obtain its table of contents entrance, and obtains the father table of contents table of contents entrance with file_inode->d_entry->d_parent.
LIDS protection construction of data
After analyzing the Linux filing system, how lets us have a look at LIDS is to accommodate the VFS guard file and the table of contents.
In /usr/src/Linux/fs/lids.c
struct secure_ino {
unsigned long int ino; /* the inode number */
kdev_t dev; /* the dev number */
int type; /* the file type */
};
The above structure uses a pair of storage protection document or the table of contents point. “type” uses for to mark the protection point document type.
LIDS has 4 types
In /usr/src/Linux/include/Linux/fs.h
#define LIDS_APPEND 1/* APPEND ONLY FILE */
#define LIDS_READONLY 2/* Read Only File */
#define LIDS_DEVICE 3/* Protect MBR Writing to device */
#define LIDS_IGNORE 4/* Ignore the protection */
Through the secure_ino structure, we can very easy initially cause the protection document perhaps carry out the following function in the essence.
In /usr/src/Linux/fs/lids.c
int lids_add_inode (unsigned long int inode, kdev_t dev, int type)
{
Looks like you to be possible to see in the above code, adds to a point to secure_ino is very easy. The point which protects in system initiation time at the beginning of causes. Initially causes the procedure in /usr/src/Linux/fs/lids.c init_vfs_security().
Now, how lets us have a look at LIDS is to inspect whether a point already did receive the protection.
In /usr/src/Linux/fs/open.c
int do_truncate (struct dentry *dentry, unsigned long length)
{
struct inode *inode = dentry->d_inode;
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