permissions_bsfs.c File Reference

Implementation of POSIX-like permission checks for BSFS. More...

Functions
uint16_t	bsfs_effective_mode (const inode_t *ino, uint16_t uid, uint16_t gid)
	Compute the effective rwx mode (3 bits) for a caller on an inode.
int	bsfs_can_read_file (const inode_t *file, uint16_t uid, uint16_t gid)
	Check if caller can read a regular file.
int	bsfs_can_write_file (const inode_t *file, uint16_t uid, uint16_t gid)
	Check if caller can write to a regular file.
int	bsfs_can_exec_file (const inode_t *file, uint16_t uid, uint16_t gid)
	Check if caller can execute a regular file.
int	bsfs_can_traverse_dir (const inode_t *dir, uint16_t uid, uint16_t gid)
	Check if caller can traverse (search) a directory.
int	bsfs_can_list_dir (const inode_t *dir, uint16_t uid, uint16_t gid)
	Check if caller can list entries in a directory.
int	bsfs_can_modify_dir (const inode_t *dir, uint16_t uid, uint16_t gid)
	Check if caller can modify entries within a directory (w+x).
int	bsfs_can_unlink_in_sticky (const inode_t *dir, const inode_t *entry, uint16_t uid, uint16_t gid)
	Check unlink/rename permission in a sticky directory.

Detailed Description

Implementation of POSIX-like permission checks for BSFS.

Function Documentation

bsfs_can_exec_file()

int bsfs_can_exec_file	(	const inode_t *	file,
		uint16_t	uid,
		uint16_t	gid )

Check if caller can execute a regular file.

Parameters

file	Target inode.
uid	Caller user id.
gid	Caller group id.

Returns

1 if allowed; 0 otherwise.

bsfs_can_list_dir()

int bsfs_can_list_dir	(	const inode_t *	dir,
		uint16_t	uid,
		uint16_t	gid )

Check if caller can list entries in a directory.

Parameters

dir	Directory inode.
uid	Caller user id.
gid	Caller group id.

Returns

1 if allowed; 0 otherwise.

bsfs_can_modify_dir()

int bsfs_can_modify_dir	(	const inode_t *	dir,
		uint16_t	uid,
		uint16_t	gid )

Check if caller can modify entries within a directory (w+x).

Parameters

dir	Directory inode.
uid	Caller user id.
gid	Caller group id.

Returns

1 if allowed; 0 otherwise.

bsfs_can_read_file()

int bsfs_can_read_file	(	const inode_t *	file,
		uint16_t	uid,
		uint16_t	gid )

Check if caller can read a regular file.

Parameters

file	Target inode.
uid	Caller user id.
gid	Caller group id.

Returns

1 if allowed; 0 otherwise.

bsfs_can_traverse_dir()

int bsfs_can_traverse_dir	(	const inode_t *	dir,
		uint16_t	uid,
		uint16_t	gid )

Check if caller can traverse (search) a directory.

Parameters

dir	Directory inode.
uid	Caller user id.
gid	Caller group id.

Returns

1 if allowed; 0 otherwise.

bsfs_can_unlink_in_sticky()

int bsfs_can_unlink_in_sticky	(	const inode_t *	dir,
		const inode_t *	entry,
		uint16_t	uid,
		uint16_t	gid )

Check unlink/rename permission in a sticky directory.

If the directory has sticky bit set (S_ISVTX), only root, the directory owner, or the entry owner may remove/rename entries inside it.

Parameters

dir	Parent directory inode.
entry	Entry inode (file or subdirectory) to remove/rename.
uid	Caller user id.
gid	Caller group id (unused here).

Returns

1 if allowed, 0 otherwise.

bsfs_can_write_file()

int bsfs_can_write_file	(	const inode_t *	file,
		uint16_t	uid,
		uint16_t	gid )

Check if caller can write to a regular file.

Parameters

file	Target inode.
uid	Caller user id.
gid	Caller group id.

Returns

1 if allowed; 0 otherwise.

bsfs_effective_mode()

uint16_t bsfs_effective_mode	(	const inode_t *	ino,
		uint16_t	uid,
		uint16_t	gid )

Compute the effective rwx mode (3 bits) for a caller on an inode.

Parameters

ino	Target inode.
uid	Caller user id.
gid	Caller group id.

Returns

3-bit mask (r=4, w=2, x=1) for the caller class; root returns 7.