RIGHTS(4) FreeBSD Kernel Interfaces Manual RIGHTS(4)
NAME
Capability rights - Capsicum capability rights for file descriptors
DESCRIPTION
When a file descriptor is created by a function such as accept(2),
accept4(2), fhopen(2), kqueue(2), mq_open(2), open(2), openat(2),
pdfork(2), pipe(2), shm_open(2), socket(2) or socketpair(2), it is
assigned all capability rights. Those rights can be reduced (but never
expanded) by using the cap_rights_limit(2), cap_fcntls_limit(2) and
cap_ioctls_limit(2) 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
cap_rights_t type is used to store list of capability rights. The
cap_rights_init(3) 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_np(3).
CAP_ACL_DELETE Permit acl_delete_fd_np(3).
CAP_ACL_GET Permit acl_get_fd(3) and acl_get_fd_np(3).
CAP_ACL_SET Permit acl_set_fd(3) and acl_set_fd_np(3).
CAP_BIND When not in capabilities mode, permit bind(2) and
bindat(2) with special value AT_FDCWD in the fd
parameter. 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 When not in capabilities mode, permit connect(2) and
connectat(2) with special value AT_FDCWD in the fd
parameter. This right is 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_fd(2).
CAP_EXTATTR_GET Permit extattr_get_fd(2).
CAP_EXTATTR_LIST Permit extattr_list_fd(2).
CAP_EXTATTR_SET Permit extattr_set_fd(2).
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_limit(2) system call.
CAP_FEXECVE Permit fexecve(2) and openat(2) with the O_EXEC
flag; CAP_READ is also 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_fsync(2), fdatasync(2), 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 futimens(2) and futimes(2), and permit
futimesat(2) and utimensat(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_limit(2) 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 changelist
argument is non-NULL).
CAP_KQUEUE_EVENT Permit kevent(2) on a kqueue(2) descriptor that
monitors events (the eventlist argument is non-
NULL). CAP_EVENT is also required on file
descriptors that will be monitored using kevent(2).
CAP_LINKAT_SOURCE Permit linkat(2) on the source directory descriptor.
This right includes the CAP_LOOKUP right.
Warning: CAP_LINKAT_SOURCE makes it possible to link
files in a directory for which file descriptors
exist that have additional rights. For example, a
file stored in a directory that does not allow
CAP_READ may be linked in another directory that
does allow CAP_READ, thereby granting read access to
a file that is otherwise unreadable.
CAP_LINKAT_TARGET Permit linkat(2) on the target 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_fd(3).
CAP_MAC_SET Permit mac_set_fd(3).
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_PEELOFF Permit sctp_peeloff(2).
CAP_PREAD An alias to CAP_READ and CAP_SEEK.
CAP_PWRITE An alias to CAP_SEEK and CAP_WRITE.
CAP_READ Permit aio_read(2) (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_SOURCE Permit renameat(2) on the source directory
descriptor. This right includes the CAP_LOOKUP
right.
Warning: CAP_RENAMEAT_SOURCE makes it possible to
move files to a directory for which file descriptors
exist that have additional rights. For example, a
file stored in a directory that does not allow
CAP_READ may be moved to another directory that does
allow CAP_READ, thereby granting read access to a
file that is otherwise unreadable.
CAP_RENAMEAT_TARGET Permit renameat(2) on the target 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_getvalue(3).
CAP_SEM_POST Permit sem_post(3).
CAP_SEM_WAIT Permit sem_wait(3) and sem_trywait(3).
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_write(2), 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_write(2), pwrite(2) and pwritev(2) CAP_SEEK is
also required.
SEE ALSO
accept(2), accept4(2), aio_fsync(2), aio_read(2), aio_write(2), bind(2),
bindat(2), cap_enter(2), cap_fcntls_limit(2), cap_ioctls_limit(2),
cap_rights_limit(2), chflagsat(2), connect(2), connectat(2),
extattr_delete_fd(2), extattr_get_fd(2), extattr_list_fd(2),
extattr_set_fd(2), fchflags(2), fchmod(2), fchmodat(2), fchown(2),
fchownat(2), fcntl(2), fexecve(2), fhopen(2), flock(2), fpathconf(2),
fstat(2), fstatat(2), fstatfs(2), fsync(2), ftruncate(2), futimes(2),
getpeername(2), getsockname(2), getsockopt(2), ioctl(2), kevent(2),
kqueue(2), linkat(2), listen(2), mmap(2), mq_open(2), open(2), openat(2),
pdfork(2), pdgetpid(2), pdkill(2), pdwait4(2), pipe(2), poll(2),
pread(2), preadv(2), pwrite(2), pwritev(2), read(2), readv(2), recv(2),
recvfrom(2), recvmsg(2), renameat(2), sctp_peeloff(2), select(2),
send(2), sendmsg(2), sendto(2), setsockopt(2), shm_open(2), shutdown(2),
socket(2), socketpair(2), symlinkat(2), unlinkat(2), write(2), writev(2),
acl_delete_fd_np(3), acl_get_fd(3), acl_get_fd_np(3), acl_set_fd(3),
acl_set_fd_np(3), acl_valid_fd_np(3), mac_get_fd(3), mac_set_fd(3),
sem_getvalue(3), sem_post(3), sem_trywait(3), sem_wait(3), capsicum(4),
snp(4)
HISTORY
Support for capabilities and capabilities mode was developed as part of
the TrustedBSD Project.
AUTHORS
This manual page was created by Pawel Jakub Dawidek <pawel@dawidek.net>
under sponsorship from the FreeBSD Foundation based on the cap_new(2)
manual page by Robert Watson <rwatson@FreeBSD.org>.
FreeBSD 13.1-RELEASE-p6 February 28, 2019 FreeBSD 13.1-RELEASE-p6
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