keyctl_capabilities(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | LINKING | SEE ALSO | COLOPHON

KEYCTL_CAPABILITIES(3) Linux Key Management Calls KEYCTL_CAPABILITIES(3)

NAME         top

       keyctl_capabilities - Query subsystem capabilities

SYNOPSIS         top

       #include <keyutils.h>

       long keyctl_capabilities(unsigned char *buffer, size_t buflen);

DESCRIPTION         top

       keyctl_capabilities() queries the keyrings subsystem in the
       kernel to ask about its capabilities and fills in the array in
       the buffer with bits that indicate the presence or absence of
       specific features in the keyrings subsystem.

       The function returns the amount of data the kernel has available,
       irrespective of the amount of buffer space available.  If the
       buffer is shorter than the data, a short copy will be made; if
       the buffer is larger than the data, the excess space will be
       cleared.

       If this operation is not available in the kernel, the keyutils
       library will emulate it as best it can and the capability bit
       that indicates if the kernel operation is available will be
       cleared.

       In buffer[0], the following capabilities exist:

       KEYCTL_CAPS0_CAPABILITIES
              This is set if the kernel supports this operation and
              cleared otherwise.  If it is cleared, the rest of the
              flags are emulated.

       KEYCTL_CAPS0_PERSISTENT_KEYRINGS
              This is set if the kernel supports persistent keyrings and
              cleared otherwise.  See keyctl_get_persistent(3).

       KEYCTL_CAPS0_DIFFIE_HELLMAN
              This is set if the kernel supports Diffie-Hellman
              calculation and cleared otherwise.  See
              keyctl_dh_compute(3).

       KEYCTL_CAPS0_PUBLIC_KEY
              This is set if the kernel supports public-key operations
              and cleared otherwise.  See keyctl_pkey_query(3).

       KEYCTL_CAPS0_BIG_KEY
              This is set if the kernel supports the big_key key type
              and cleared otherwise.

       KEYCTL_CAPS0_INVALIDATE
              This is set if the kernel supports key invalidation and
              cleared otherwise.  See keyctl_invalidate(3).

       KEYCTL_CAPS0_RESTRICT_KEYRING
              This is set if the kernel supports restrictions on
              keyrings and cleared otherwise.  See
              keyctl_restrict_keyring(3).

       KEYCTL_CAPS0_MOVE
              This is set if the kernel supports the move key operation
              and cleared otherwise.  See keyctl_move(3).

       In buffer[1], the following capabilities exist:

       KEYCTL_CAPS1_NS_KEYRING_NAME
              This is set if the keyring names are segregated according
              to the user-namespace in which a keyring is created.

       KEYCTL_CAPS1_NS_KEY_TAG
              This is set if a key or keyring may get tagged with a
              namespace, thereby allowing multiple keys with the same
              type and description, but different namespace tags, to
              coexist within the same keyring.  Tagging may be automatic
              depending on the key type.  Only network-namespace tagging
              is currently used.

RETURN VALUE         top

       On success keyctl_capabilities() returns the size of the data it
       has available, irrespective of the size of the buffer.  On error,
       the value -1 will be returned and errno will have been set to an
       appropriate error.

ERRORS         top

       EFAULT The buffer cannot be written to.

LINKING         top

       This is a library function that can be found in libkeyutils.
       When linking, -lkeyutils should be specified to the linker.

SEE ALSO         top

       keyctl(1), add_key(2), keyctl(2), request_key(2), keyctl(3),
       keyrings(7), keyutils(7)

COLOPHON         top

       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 2021-04-01.  (At that time, the date of the most recent commit
       that was found in the repository was 2020-07-07.)  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                          30 May 2019        KEYCTL_CAPABILITIES(3)

Pages that refer to this page: keyctl(3)