KEYCTL_READ
Section: Linux Key Management Calls (3)
Updated: 21 Feb 2014
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NAME
keyctl_read - read a key
SYNOPSIS
#include <keyutils.h>
long keyctl_read(key_serial_t key, char *buffer, size_t buflen);
long keyctl_read_alloc(key_serial_t key, void **_buffer);
DESCRIPTION
keyctl_read()
reads the payload of a key if the key type supports it.
The caller must have
read
permission on a key to be able to read it.
buffer
and
buflen
specify the buffer into which the payload data will be placed. If the buffer
is too small, then the full size of the payload will be returned, and the
contents of the buffer may be overwritten in some undefined way.
keyctl_read_alloc()
is similar to
keyctl_read()
except that it allocates a buffer big enough to hold the payload data and
places the data in it. If successful, a pointer to the buffer is placed in
*_buffer.
The caller must free the buffer.
keyctl_read_alloc()
adds a NUL character after the data it retrieves, though this is not counted
in the size value it returns.
READING KEYRINGS
This call can be used to list the contents of a keyring. The data is
presented to the user as an array of
key_serial_t
values, each of which corresponds to a key to which the keyring holds a link.
The size of the keyring will be sizeof(key_serial_t) multiplied by the number
of keys. The size of key_serial_t is invariant across different word sizes,
though the byte-ordering is as appropriate for the kernel.
RETURN VALUE
On success
keyctl_read()
returns the amount of data placed into the buffer. If the buffer was too
small, then the size of buffer required will be returned, and the contents of
the buffer may have been overwritten in some undefined way.
On success
keyctl_read_alloc()
returns the amount of data in the buffer.
On error, both functions set
errno
to an appropriate code and return the value
-1.
ERRORS
- ENOKEY
-
The key specified is invalid.
- EKEYEXPIRED
-
The key specified has expired.
- EKEYREVOKED
-
The key specified had been revoked.
- EACCES
-
The key exists, but is not
readable
by the calling process.
- EOPNOTSUPP
-
The key type does not support reading of the payload data.
LINKING
This is a library function that can be found in
libkeyutils.
When linking,
-lkeyutils
should be specified to the linker.
SEE ALSO
keyctl(1),
add_key(2),
keyctl(2),
request_key(2),
keyctl(3),
keyrings(7),
keyutils(7)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- READING KEYRINGS
-
- RETURN VALUE
-
- ERRORS
-
- LINKING
-
- SEE ALSO
-
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Time: 10:42:19 GMT, March 29, 2024