возможность манипулирования файлами (capability manipulation on files)
Имя (Name)
cap_get_file, cap_set_file, cap_get_fd, cap_set_fd - capability
manipulation on files
Синопсис (Synopsis)
#include <sys/capability.h>
cap_t cap_get_file(const char *path_p);
int cap_set_file(const char *path_p, cap_t cap_p);
cap_t cap_get_fd(int fd);
int cap_set_fd(int fd, cap_t caps);
uid_t cap_get_nsowner(cap_t caps);
int cap_set_nsowner(cap_t caps, uid_t rootuid);
Link with -lcap.
Описание (Description)
cap_get_file() and cap_get_fd() allocate a capability state in
working storage and set it to represent the capability state of
the pathname pointed to by path_p or the file open on descriptor
fd. These functions return a pointer to the newly created
capability state. The effects of reading the capability state
from any file other than a regular file is undefined. The caller
should free any releasable memory, when the capability state in
working storage is no longer required, by calling cap_free() with
the used cap_t as an argument.
cap_set_file() and cap_set_fd() set the values for all capability
flags for all capabilities for the pathname pointed to by path_p
or the file open on descriptor fd, with the capability state
identified by cap_p. The new capability state of the file is
completely determined by the contents of cap_p. A NULL value for
cap_p is used to indicate that capabilities for the file should
be deleted. For these functions to succeed, the calling process
must have the CAP_SETFCAP capability in its effective set and
either the effective user ID of the process must match the file
owner or the calling process must have the CAP_FOWNER capability
in its effective capability set. The effects of writing the
capability state to any file type other than a regular file are
undefined.
A capability set held in memory can be associated with the root
user ID in use in a specific user namespace. It is possible to
get and set this value (in the memory copy) with
cap_get_nsowner() and cap_set_nsowner() respectively. The root
user ID is ignored by the libcap library in all cases other than
when the capability is written to a file. Only if the value is
non-zero will the library attempt to include it in the written
file capability set.
Возвращаемое значение (Return value)
cap_get_file() and cap_get_fd() return a non-NULL value on
success, and NULL on failure.
cap_set_file() and cap_set_fd() return zero on success, and -1 on
failure.
On failure, errno is set to EACCES, EBADFD, ENAMETOOLONG, ENOENT,
ENOMEM, ENOTDIR, EPERM, or EROFS.
Стандарты (Conforming to)
These functions are specified by withdrawn POSIX.1e draft
specification.
Примечание (Note)
Support for file capabilities is provided on Linux since version
2.6.24.
On Linux, the file Effective set is a single bit. If it is
enabled, then all Permitted capabilities are enabled in the
Effective set of the calling process when the file is executed;
otherwise, no capabilities are enabled in the process's Effective
set following an execve(2). Because the file Effective set is a
single bit, if any capability is enabled in the Effective set of
the cap_t given to cap_set_file() or cap_set_fd(), then all
capabilities whose Permitted or Inheritable flag is enabled must
also have the Effective flag enabled. Conversely, if the
Effective bit is enabled on a file, then the cap_t returned by
cap_get_file() and cap_get_fd() will have the Effective flag
enabled for each capability that has the Permitted or Inheritable
flag enabled.
Смотри также (See also)
libcap(3), cap_clear(3), cap_copy_ext(3), cap_from_text(3),
cap_get_proc(3), cap_init(3), capabilities(7), user_namespaces(7)
