CAPGET
Section: Linux Programmer's Manual (2)
Updated: 2004-06-21
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NAME
capget, capset - set/get process capabilities
SYNOPSIS
#undef _POSIX_SOURCE
#include <sys/capability.h>
int capget(cap_user_header_t hdrp, cap_user_data_t datap);
int capset(cap_user_header_t hdrp, const cap_user_data_t datap);
DESCRIPTION
As of Linux 2.2, the power of the superuser (root) has been partitioned into
a set of discrete capabilities.
Every process has a set of effective capabilities identifying
which capabilities (if any) it may currently exercise.
Every process also has a set of inheritable capabilities that may be
passed through an
execve(2)
call, and a set of permitted capabilities
that it can make effective or inheritable.
These two functions are the raw kernel interface for getting and
setting capabilities. Not only are these system calls specific to Linux,
but the kernel API is likely to change and use of
these functions (in particular the format of the
cap_user_*_t
types) is subject to change with each kernel revision.
The portable interfaces are
cap_set_proc(3)
and
cap_get_proc(3);
if possible you should use those interfaces in applications.
If you wish to use the Linux extensions in applications, you should
use the easier-to-use interfaces
capsetp(3)
and
capgetp(3).
Current details
Now that you have been warned, some current kernel details.
The structs are defined as follows.
#define _LINUX_CAPABILITY_VERSION 0x19980330
typedef struct __user_cap_header_struct {
int version;
int pid;
} *cap_user_header_t;
typedef struct __user_cap_data_struct {
int effective;
int permitted;
int inheritable;
} *cap_user_data_t;
The calls will return EINVAL, and set the version field of
hdr
to _LINUX_CAPABILITY_VERSION when another version was specified.
The calls refer to the capabilities of the process indicated by
the pid field of
hdr
when that is nonzero, or to the current process otherwise.
For details on the data, see
capabilities(7).
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and
errno
is set appropriately.
ERRORS
- EFAULT
-
Bad memory address. Neither of
hdrp
and
datap
may be NULL.
- EINVAL
-
One of the arguments was invalid.
- EPERM
-
An attempt was made to add a capability to the Permitted set, or to set
a capability in the Effective or Inheritable sets that is not in the
Permitted set.
- EPERM
-
The calling process attempted to use
capset()
to modify the capabilities of a process other than itself,
but lacked sufficient privilege; the
CAP_SETPCAP
capability is required.
- ESRCH
-
No such process.
FURTHER INFORMATION
The portable interface to the capability querying and setting
functions is provided by the
libcap
library and is available from here:
ftp://ftp.kernel.org/pub/linux/libs/security/linux-privs
SEE ALSO
capabilities(7)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- Current details
-
- RETURN VALUE
-
- ERRORS
-
- FURTHER INFORMATION
-
- SEE ALSO
-
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