Rule Set Based Access Control (RSBAC) - Targets and Requests

| # Rule Set Based Access Control (RSBAC) for Linux - Targets and Requests

## Targets

RSBAC restricts access by subjects to objects. The subjects are always processes, acting on behalf of a user with certain attributes, like system_role etc. Objects in RSBAC are called (Access) Targets. They are grouped in Target Types. The following types are defined:

FILE | Files, including device special files. Identified by device and inode number.
DIR | Directories, identified by device and inode number.
FIFO | (new in v1.1.1) FIFO special files
DEV | Devices, identified by type (char or block), major and minor number
IPC | InterProcess Communication: Semaphores (sem), Messages (msg), Shared Memory (shm), Sockets (sock) and FiFo (fifo, removed in 1.1.1).
SCD | System Control Data: Objects affecting the whole system. This target type is the only one with a fixed number of objects, identified by number (see below).
USER | Users as objects, mostly for access control information (ACI).
PROCESS | Processes as objects.
NETDEV | Network Device, identified by name.
NETTEMP | Network Template, identified by index number. Access control: access to template itself, RC Administration: access to values/settings for both template and NETOBJ, ACL administration: Default ACLs for NETOBJ
NETOBJ | Network Object, identified by internal pointer to struct socket. Attribute values mostly inherited from NETTEMP settings.
NETTEMP_NT | ACL administration only, ACL entries for NETTEMP objects themselves.
NONE | No object associated with this request. In some models (RC, ACL) this is internally changed into SCD target "other".
FD | (Only in user space): Let the command line tool decide between types FILE and DIR

System Control Data (SCD) targets are these:

time_strucs | System timer
clock | System time and date
host_id | Host name
net_id | Domain name
ioports | Access Control for direct hardware access
rlimit | Setting process ressource limits
swap | Control of swapping
syslog | System log
rsbac | RSBAC data in /proc
rsbaclog | RSBAC own log
kmem | Direct access to kernel memory via proc or device
other | MODIFY_SYSTEM_DATA for sysctl, otherwise only internal in RC and ACL: Substitute for target NONE
auth_administration | (only in RC and ACL): AUTH model administration
network | General networking, like routing, arp etc. (Devices are protected as NETDEV targets!)
firewall | Firewall settings, packet filter etc.

## Requests

Before access to a target is granted, a request call to the Access Control Decision facility (ADF) is performed. Based on the request type and the target, access can be granted or denied.

RSBAC requests and the system calls they are issued from are listed in the following table. Please note that some requests are only issued under certain conditions, e.g. EXECUTE from mmap() only, if mapping request is for EXEC mode. Also, some calls depend on the kernel configuration settings, e.g. RSBAC net support.

Some calls are done from common helper functions, e.g. do_fork(). Those functions that also perform the rsbac_adf_set_attr() notification call for the request are marked with an *.

Additionally, some requests provide extra data with kernel internal attribute types. These attributes are: A_group, A_sockaddr_p, A_signal, A_mode, A_nlink, A_switch_target, A_mod_name, A_request, A_ms_segment, A_trace_request, A_auth_add_f_cap, A_auth_remove_f_cap, A_auth_get_caplist, A_prot_bits. Please have a look into include/rsbac/types.h for the respective data types.

Request | Description | Valid Target Types | System calls and functions
--- | --- | --- | ---
ADD_TO_KERNEL | Add a kernel module | NONE | create_module(NONE), init_module(NONE)
ALTER | Change IPC control information | IPC | msgctl(IPC), shmctl(IPC)
APPEND_OPEN | Open to append | FILE, DEV, IPC | open(FILE,DEV)*, msgsnd(IPC)*, sendto(IPC)*, sendmsg(IPC)*
CHANGE_GROUP | Change active group | IPC, PROCESS, NONE | setgid(PROC), setregid(PROC), setresgid(PROC), setgroups(PROC), setfsgid(NONE) (for DAC only), shmctl(IPC), msgctl(IPC)
CHANGE_OWNER | Change owner | FILE, DIR, FIFO, IPC, PROCESS, NONE | chown(FILE, DIR, FIFO), lchown(FILE, DIR, FIFO), fchown(FILE, DIR, FIFO), setuid(PROC)*, setreuid(PROC)*, setresuid(PROC)*, setfsuid(NONE) (for DAC only), shmctl(IPC), msgctl(IPC)
CHDIR | Change working directory | DIR | chdir(DIR), fchdir(DIR), chroot(DIR)
CLONE | Fork/clone a process | PROCESS | fork(PROC)*, vfork(PROC)*, clone(PROC)*
CLOSE | Close opened file etc. Should always be granted. | FILE, DIR, FIFO, DEV, IPC, NETOBJ | close(FILE, DIR, FIFO, DEV, IPC, NETOBJ)*, shmdt(IPC)*, msgrcv(IPC)*, msgsnd(IPC)*, send(IPC)*, sendto(IPC)*, sendmsg(IPC)*, recv(IPC)*, recvfrom(IPC)*, recvmsg(IPC)*
CREATE | Create object | DIR (where), IPC, NETTEMP, NETOBJ | creat(DIR, IPC)*, open(DIR, IPC)*, mknod(DIR)*, mkdir(DIR)*, symlink(DIR)*, shmget(IPC)*, msgget(IPC)*, socket(IPC)*, accept(IPC)*, rsbac_net_temp(NETTEMP), socket(NETOBJ)
DELETE | Delete object | FILE, DIR, FIFO, IPC | unlink(FILE, DIR, FIFO)*, rmdir(DIR)*, msgctl(IPC)*, shmctl(IPC)*, shutdown(IPC)*. close(IPC)*, rsbac_net_temp(NETTEMP)
EXECUTE | Execute a file (until v1.1.2: also map library file/other code executable, see MAP_EXEC) | FILE | exec()*
GET_PERMISSIONS_DATA | Read Unix permissions (mode) | FILE, DIR, FIFO | access(FILE, DIR, FIFO)
GET_STATUS_DATA | Get status (stat() etc.) | FILE, DIR, FIFO, IPC, SCD, NETDEV | open_port(SCD) (/dev/kmem etc.), open_kcore(SCD) (/proc/kcore), stat(FILE, DIR, FIFO, IPC), newstat(FILE, DIR, FIFO, IPC), lstat(FILE, DIR, FIFO, IPC), newlstat(FILE, DIR, FIFO, IPC), fstat(FILE, DIR, FIFO, IPC), newfstat(FILE, DIR, FIFO, IPC), stat64(FILE, DIR, FIFO, IPC), lstat64(FILE, DIR, FIFO, IPC), fstat64(FILE, DIR, FIFO, IPC), statfs(FILE, DIR, FIFO), fstatfs(FILE, DIR, FIFO), rsbac_stats(SCD), rsbac_check(SCD), rsbac_stats_pm(SCD), rsbac_stats_rc(SCD), rsbac_stats_acl(SCD), rsbac_log(SCD), (access to RSBAC proc-files(SCD)), dev_ioctl(NETDEV), arp_ioctl(NETDEV), ip_mroute_setsockopt(SCD network), firewalling code (SCD firewall)
LINK_HARD | Hard link | FILE, DIR, FIFO | link(FILE, DIR, FIFO)
MODIFY_ACCESS_DATA | Change access information, e.g. time, date | FILE, DIR, FIFO | utimes(FILE, DIR, FIFO)
MODIFY_ATTRIBUTE | Change an RSBAC attribute value | All target types | (specific request needed for various security models)
MODIFY_PERMISSIONS_DATA | Change Unix permissions | FILE, DIR, FIFO, SCD | ioperm(SCD), iopl(SCD), chmod(FILE, DIR, FIFO) , fchmod(FILE, DIR, FIFO)
MODIFY_SYSTEM_DATA | Change system settings | SCD, NETDEV | stime(SCD), settimeofday(SCD), adjtimex(SCD), sethostname(SCD), setdomainname(SCD), setrlimit(SCD), syslog(SCD), sysctl(SCD), swapon(SCD), swapoff(SCD), rsbac_log(SCD), dev_ioctl(NETDEV), arp_ioctl(NETDEV), ip_mroute_setsockopt(SCD network), firewalling code (SCD firewall)
MOUNT | Mount a filesystem | DIR, DEV | mount(DIR, DEV) (separate mount notification for data structures)
READ | Read from DIR or NETTEMP. Optional: read from other objects | DIR, NETTEMP (optional: FILE, FIFO, DEV, IPC, NETOBJ) | read(FILE, FIFO, DEV, IPC, NETOBJ)*, readv(FILE, FIFO, DEV, IPC)*, pread(FILE, DEV, IPC)*, readdir(DIR), open(DIR), rsbac_net_temp(NETTEMP)
READ_ATTRIBUTE | Read RSBAC attribute value | All target types | (specific request needed for various security models)
READ_OPEN | Open for read | FILE, FIFO, DEV, IPC | open(FILE, FIFO, DEV, IPC)*, shmat(IPC)*, msgrcv(IPC)*, recv(IPC)*, recvfrom(IPC)*, recvmsg(IPC)*
READ_WRITE_OPEN | Open for read and write | FILE, FIFO, DEV, IPC | open(FILE, FIFO, DEV, IPC)*, shmat(IPC)*, bind(IPC)*, connect(IPC)*, listen(IPC)*
REMOVE_FROM_KERNEL | Remove kernel module | NONE | delete_module(NONE)
RENAME | Rename | FILE, DIR, FIFO | rename(FILE, DIR, FIFO) (RSBAC identification not changed by rename!)
SEARCH | Lookup in dir or symlink from inside kernel for access with full path | DIR, SYMLINK | (internal functions lookup_dentry(DIR) / path_walk(DIR) / lookup_hash(DIR) / follow_symlink(SYMLINK))
SEND_SIGNAL | Send a signal | PROCESS | kill(PROC)
SHUTDOWN | Shutdown/reboot system | NONE | reboot(NONE)
SWITCH_LOG | Change RSBAC log settings | NONE | rsbac_adf_log_switch(NONE)
SWITCH_MODULE | Switch decision module on/off | NONE | rsbac_switch(NONE)
TERMINATE | End of calling process, for attribute cleanup. Should always be granted. | PROCESS | exit(PROC)
TRACE | Trace a process | PROCESS | ptrace(PROC) (architecture dependent)
TRUNCATE | Truncate | FILE | open(FILE)*, truncate(FILE)*, ftruncate(FILE)*, truncate64(FILE)*, ftruncate64(FILE)*
UMOUNT | Umount a filesystem | DIR, DEV | umount(DIR, DEV) (separate umount notification for data structures)
WRITE | Write to a DIR, SCD or NETTEMP. Used for object moving to target dir. Optional: write to file etc. | DIR, SCD (optional: FILE, FIFO, DEV, IPC-sock) | write(FILE, FIFO, IPC, DEV, NETTEMP)*, writev(FILE, FIFO, IPC, DEV)*, pwrite(FILE, IPC, DEV)*, rename(DIR), rsbac_write(SCD), rsbac_net_temp(NETTEMP)
WRITE_OPEN | Open for write | FILE, FIFO, DEV, IPC | open(FILE, FIFO, DEV, IPC)*
MAP_EXEC | Map a library from a file (target FILE) or other code (target NONE) for execution. | FILE, NONE | mmap(FILE) (EXEC mode), mprotect(FILE, NONE) (EXEC mode), uselib(FILE)
BIND | Bind network address and port (if applicable) to local socket, bind to network device | NETDEV, NETOBJ | dev_ioctl(NETDEV), bind()*
LISTEN | Listen on a local socket | NETOBJ | listen()*
ACCEPT | Accept a connection from a remote network endpoint | NETOBJ | accept()*
CONNECT | Connect to remote network endpoint | NETOBJ | connect()*
SEND | Send to remote network endpoint | NETOBJ | send()*, sendmsg()*, sendto()*
RECEIVE | Receive from remote network endpoint | NETOBJ | recv()*, recvmsg()*, recvfrom()*
NET_SHUTDOWN | Shutdown channel of local socket | NETOBJ | shutdown()

Please remember that some models (RC, ACL) internally change NONE targets to SCD target "other" for access control.

Questions, tips, etc.

28-May-02, -ao