ADD_KEY

NAME

SYNOPSIS

#include <sys/types.h>
#include <keyutils.h>

key_serial_t add_key(const char *type, const char *description,
                     const void *payload, size_t plen,
                     key_serial_t keyring);

Note: There is no glibc wrapper for this system call; see NOTES.  

DESCRIPTION

The key may be rejected if the provided data is in the wrong format or it is invalid in some other way.

If the destination keyring already contains a key that matches the specified type and description, then, if the key type supports it, that key will be updated rather than a new key being created; if not, a new key (with a different ID) will be created and it will displace the link to the extant key from the keyring.

The destination keyring serial number may be that of a valid keyring for which the caller has write permission. Alternatively, it may be one of the following special keyring IDs:

KEY_SPEC_THREAD_KEYRING

This specifies the caller's thread-specific keyring (thread-keyring(7)).

KEY_SPEC_PROCESS_KEYRING

This specifies the caller's process-specific keyring (process-keyring(7)).

KEY_SPEC_SESSION_KEYRING

This specifies the caller's session-specific keyring (session-keyring(7)).

KEY_SPEC_USER_KEYRING

This specifies the caller's UID-specific keyring (user-keyring(7)).

KEY_SPEC_USER_SESSION_KEYRING

This specifies the caller's UID-session keyring (user-session-keyring(7)).

Key types

keyring

Keyrings are special key types that may contain links to sequences of other keys of any type. If this interface is used to create a keyring, then payload should be NULL and plen should be zero.

"user"

This is a general purpose key type whose payload may be read and updated by user-space applications. The key is kept entirely within kernel memory. The payload for keys of this type is a blob of arbitrary data of up to 32,767 bytes.

"logon" (since Linux 3.3)

This key type is essentially the same as "user", but it does not permit the key to read. This is suitable for storing payloads that you do not want to be readable from user space.

This key type vets the description to ensure that it is qualified by a "service" prefix, by checking to ensure that the description contains a ':' that is preceded by other characters.

"big_key" (since Linux 3.13)

This key type is similar to "user", but may hold a payload of up to 1 MiB. If the key payload is large enough, then it may be stored encrypted in tmpfs (which can be swapped out) rather than kernel memory.

For further details on these key types, see keyrings(7).  

RETURN VALUE

ERRORS

EACCES

The keyring wasn't available for modification by the user.

EDQUOT

The key quota for this user would be exceeded by creating this key or linking it to the keyring.

EFAULT

One or more of type, description, and payload points outside process's accessible address space.

EINVAL

The size of the string (including the terminating null byte) specified in type or description exceeded the limit (32 bytes and 4096 bytes respectively).

EINVAL

The payload data was invalid.

EINVAL

type was "logon" and the description was not qualified with a prefix string of the form "service:".

EKEYEXPIRED

The keyring has expired.

EKEYREVOKED

The keyring has been revoked.

ENOKEY

The keyring doesn't exist.

ENOMEM

Insufficient memory to create a key.

EPERM

The type started with a period ('.'). Key types that begin with a period are reserved to the implementation.

EPERM

type was keyring and the description started with a period ('.'). Keyrings with descriptions (names) that begin with a period are reserved to the implementation.

VERSIONS

CONFORMING TO

NOTES

EXAMPLES

$ ./a.out user mykey "Some payload" Key ID is 64a4dca $ grep '64a4dca' /proc/keys 064a4dca I--Q--- 1 perm 3f010000 1000 1000 user mykey: 12  

Program source

int main(int argc, char *argv[]) {
    key_serial_t key;

    if (argc != 4) {
        fprintf(stderr, "Usage: %s type description payload\n",
                argv[0]);
        exit(EXIT_FAILURE);
    }

    key = add_key(argv[1], argv[2], argv[3], strlen(argv[3]),
                KEY_SPEC_SESSION_KEYRING);
    if (key == -1) {
        perror("add_key");
        exit(EXIT_FAILURE);
    }

    printf("Key ID is %jx\n", (uintmax_t) key);

    exit(EXIT_SUCCESS); }  

SEE ALSO

The kernel source files Documentation/security/keys/core.rst and Documentation/keys/request-key.rst (or, before Linux 4.13, in the files Documentation/security/keys.txt and Documentation/security/keys-request-key.txt).  

COLOPHON

Index

NAME

SYNOPSIS

DESCRIPTION

Key types

RETURN VALUE

ERRORS

VERSIONS

CONFORMING TO

NOTES

EXAMPLES

Program source

SEE ALSO

COLOPHON