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NAME | SYNOPSIS | DESCRIPTION | READING KEYRINGS | RETURN VALUE | ERRORS | LINKING | SEE ALSO | COLOPHON |
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KEYCTL_READ(3) Linux Key Management Calls KEYCTL_READ(3)
keyctl_read - read a key
#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);
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.
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.
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.
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The key specified had been revoked.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.
This is a library function that can be found in libkeyutils.
When linking, -lkeyutils should be specified to the linker.
keyctl(1), add_key(2), keyctl(2), request_key(2), keyctl(3),
keyrings(7), keyutils(7)
This page is part of the keyutils (key management utilities)
project. Information about the project can be found at [unknown
-- if you know, please contact man-pages@man7.org] If you have a
bug report for this manual page, send it to
keyrings@linux-nfs.org. This page was obtained from the
project's upstream Git repository
⟨http://git.kernel.org/pub/scm/linux/kernel/git/dhowells/keyutils.git⟩
on 2024-06-14. (At that time, the date of the most recent commit
that was found in the repository was 2023-03-20.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
Linux 21 Feb 2014 KEYCTL_READ(3)
Pages that refer to this page: keyctl(2), request_key(2), keyctl(3)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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