DESCRIPTION

When a file descriptor is created by a function such as accept(2), accept4(2), fhopen(2), kqueue(2), mq_open2, open(2), openat(2), pdfork(2), pipe(2), shm_open2, socket(2) or socketpair(2), it is assigned all capability rights. Those rights can be reduced (but never expanded) by using the cap_rights_limit2, cap_fcntls_limit2and cap_ioctls_limit2 system calls. Once capability rights are reduced, operations on the file descriptor will be limited to those permitted by rights.

The complete list of capability rights is provided below. The Vt cap_rights_t type is used to store list of capability rights. The cap_rights_init3 family of functions should be used to manage the structure.

RIGHTS

The following rights may be specified in a rights mask:

CAP_ACCEPT

Permit accept(2) and accept4(2).

CAP_ACL_CHECK

Permit acl_valid_fd_np3.

CAP_ACL_DELETE

Permit acl_delete_fd_np3.

CAP_ACL_GET

Permit acl_get_fd3 and acl_get_fd_np3.

CAP_ACL_SET

Permit acl_set_fd3 and acl_set_fd_np3.

CAP_BIND

Permit bind(2). Note that sockets can also become bound implicitly as a result of connect(2) or send(2), and that socket options set with setsockopt(2) may also affect binding behavior.

CAP_BINDAT

Permit bindat(2). This right has to be present on the directory descriptor. This right includes the CAP_LOOKUP right.

CAP_CHFLAGSAT

An alias to CAP_FCHFLAGS and CAP_LOOKUP

CAP_CONNECT

Permit connect(2); also required for sendto(2) with a non-NULL destination address.

CAP_CONNECTAT

Permit connectat(2). This right has to be present on the directory descriptor. This right includes the CAP_LOOKUP right.

CAP_CREATE

Permit openat(2) with the O_CREAT flag.

CAP_EVENT

Permit select(2), poll(2), and kevent(2) to be used in monitoring the file descriptor for events.

CAP_EXTATTR_DELETE

Permit extattr_delete_fd2.

CAP_EXTATTR_GET

Permit extattr_get_fd2.

CAP_EXTATTR_LIST

Permit extattr_list_fd2.

CAP_EXTATTR_SET

Permit extattr_set_fd2.

CAP_FCHDIR

Permit fchdir(2).

CAP_FCHFLAGS

Permit fchflags(2) and chflagsat(2) if the CAP_LOOKUP right is also present.

CAP_FCHMOD

Permit fchmod(2) and fchmodat(2) if the CAP_LOOKUP right is also present.

CAP_FCHMODAT

An alias to CAP_FCHMOD and CAP_LOOKUP

CAP_FCHOWN

Permit fchown(2) and fchownat(2) if the CAP_LOOKUP right is also present.

CAP_FCHOWNAT

An alias to CAP_FCHOWN and CAP_LOOKUP

CAP_FCNTL

Permit fcntl(2). Note that only the F_GETFL F_SETFL F_GETOWN and F_SETOWN commands require this capability right. Also note that the list of permitted commands can be further limited with the cap_fcntls_limit2 system call.

CAP_FEXECVE

Permit fexecve(2) and openat(2) with the O_EXEC flag; CAP_READ is also be required.

CAP_FLOCK

Permit flock(2), fcntl(2) (with F_GETLK F_SETLK F_SETLKW or F_SETLK_REMOTE flag) and openat(2) (with O_EXLOCK or O_SHLOCK flag).

CAP_FPATHCONF

Permit fpathconf(2).

CAP_FSCK

Permit UFS background-fsck operations on the descriptor.

CAP_FSTAT

Permit fstat(2) and fstatat(2) if the CAP_LOOKUP right is also present.

CAP_FSTATAT

An alias to CAP_FSTAT and CAP_LOOKUP

CAP_FSTATFS

Permit fstatfs(2).

CAP_FSYNC

Permit aio_fsync2, fsync(2) and openat(2) with O_FSYNC or O_SYNC flag.

CAP_FTRUNCATE

Permit ftruncate(2) and openat(2) with the O_TRUNC flag.

CAP_FUTIMES

Permit futimes(2) and futimesat(2) if the CAP_LOOKUP right is also present.

CAP_FUTIMESAT

An alias to CAP_FUTIMES and CAP_LOOKUP

CAP_GETPEERNAME

Permit getpeername(2).

CAP_GETSOCKNAME

Permit getsockname(2).

CAP_GETSOCKOPT

Permit getsockopt(2).

CAP_IOCTL

Permit ioctl(2). Be aware that this system call has enormous scope, including potentially global scope for some objects. The list of permitted ioctl commands can be further limited with the cap_ioctls_limit2 system call.

CAP_KQUEUE

An alias to CAP_KQUEUE_CHANGE and CAP_KQUEUE_EVENT

CAP_KQUEUE_CHANGE

Permit kevent(2) on a kqueue(2) descriptor that modifies list of monitored events (the Fa changelist argument is non-NULL).

CAP_KQUEUE_EVENT

Permit kevent(2) on a kqueue(2) descriptor that monitors events (the Fa eventlist argument is non-NULL). CAP_EVENT is also required on file descriptors that will be monitored using kevent(2).

CAP_LINKAT

Permit linkat(2) and renameat(2) on the destination directory descriptor. This right includes the CAP_LOOKUP right.

CAP_LISTEN

Permit listen(2); not much use (generally) without CAP_BIND

CAP_LOOKUP

Permit the file descriptor to be used as a starting directory for calls such as linkat(2), openat(2), and unlinkat(2).

CAP_MAC_GET

Permit mac_get_fd3.

CAP_MAC_SET

Permit mac_set_fd3.

CAP_MKDIRAT

Permit mkdirat(2). This right includes the CAP_LOOKUP right.

CAP_MKFIFOAT

Permit mkfifoat(2). This right includes the CAP_LOOKUP right.

CAP_MKNODAT

Permit mknodat(2). This right includes the CAP_LOOKUP right.

CAP_MMAP

Permit mmap(2) with the PROT_NONE protection.

CAP_MMAP_R

Permit mmap(2) with the PROT_READ protection. This right includes the CAP_READ and CAP_SEEK rights.

CAP_MMAP_RW

An alias to CAP_MMAP_R and CAP_MMAP_W

CAP_MMAP_RWX

An alias to CAP_MMAP_R CAP_MMAP_W and CAP_MMAP_X

CAP_MMAP_RX

An alias to CAP_MMAP_R and CAP_MMAP_X

CAP_MMAP_W

Permit mmap(2) with the PROT_WRITE protection. This right includes the CAP_WRITE and CAP_SEEK rights.

CAP_MMAP_WX

An alias to CAP_MMAP_W and CAP_MMAP_X

CAP_MMAP_X

Permit mmap(2) with the PROT_EXEC protection. This right includes the CAP_SEEK right.

CAP_PDGETPID

Permit pdgetpid(2).

CAP_PDKILL

Permit pdkill(2).

CAP_PDWAIT

Permit pdwait4(2).

CAP_PEELOFF

Permit sctp_peeloff2.

CAP_PREAD

An alias to CAP_READ and CAP_SEEK

CAP_PWRITE

An alias to CAP_SEEK and CAP_WRITE

CAP_READ

Permit aio_read2 ( CAP_SEEK is also required), openat(2) with the O_RDONLY flag, read(2), readv(2), recv(2), recvfrom(2), recvmsg(2), pread(2) ( CAP_SEEK is also required), preadv(2) ( CAP_SEEK is also required) and related system calls.

CAP_RECV

An alias to CAP_READ

CAP_RENAMEAT

Permit renameat(2). This right is required on the source directory descriptor. This right includes the CAP_LOOKUP right.

CAP_SEEK

Permit operations that seek on the file descriptor, such as lseek(2), but also required for I/O system calls that can read or write at any position in the file, such as pread(2) and pwrite(2).

CAP_SEM_GETVALUE

Permit sem_getvalue3.

CAP_SEM_POST

Permit sem_post3.

CAP_SEM_WAIT

Permit sem_wait3 and sem_trywait3.

CAP_SEND

An alias to CAP_WRITE

CAP_SETSOCKOPT

Permit setsockopt(2); this controls various aspects of socket behavior and may affect binding, connecting, and other behaviors with global scope.

CAP_SHUTDOWN

Permit explicit shutdown(2); closing the socket will also generally shut down any connections on it.

CAP_SYMLINKAT

Permit symlinkat(2). This right includes the CAP_LOOKUP right.

CAP_TTYHOOK

Allow configuration of TTY hooks, such as snp(4), on the file descriptor.

CAP_UNLINKAT

Permit unlinkat(2) and renameat(2). This right is only required for renameat(2) on the destination directory descriptor if the destination object already exists and will be removed by the rename. This right includes the CAP_LOOKUP right.

CAP_WRITE

Allow aio_write2, openat(2) with O_WRONLY and O_APPEND flags set, send(2), sendmsg(2), sendto(2), write(2), writev(2), pwrite(2), pwritev(2) and related system calls. For sendto(2) with a non-NULL connection address, CAP_CONNECT is also required. For openat(2) with the O_WRONLY flag, but without the O_APPEND flag, CAP_SEEK is also required. For aio_write2, pwrite(2) and pwritev(2) CAP_SEEK is also required.

HISTORY

Support for capabilities and capabilities mode was developed as part of the TrustedBSD Project.

AUTHORS

This manual page was created by An Pawel Jakub Dawidek Aq [email protected] under sponsorship from the FreeBSD Foundation based on cap_new2 manual page by An Robert Watson Aq [email protected] .