Keys have an owner user ID, a group access ID, and a permissions mask. The mask
has up to eight bits each for possessor, user, group and other access. Only
-five of each set of eight bits are defined. These permissions granted are:
+six of each set of eight bits are defined. These permissions granted are:
(*) View
keyring to a key, a process must have Write permission on the keyring and
Link permission on the key.
+ (*) Set Attribute
+
+ This permits a key's UID, GID and permissions mask to be changed.
+
For changing the ownership, group ID or permissions mask, being the owner of
the key or having the sysadmin capability is sufficient.
this way:
SERIAL FLAGS USAGE EXPY PERM UID GID TYPE DESCRIPTION: SUMMARY
- 00000001 I----- 39 perm 1f1f0000 0 0 keyring _uid_ses.0: 1/4
- 00000002 I----- 2 perm 1f1f0000 0 0 keyring _uid.0: empty
- 00000007 I----- 1 perm 1f1f0000 0 0 keyring _pid.1: empty
- 0000018d I----- 1 perm 1f1f0000 0 0 keyring _pid.412: empty
- 000004d2 I--Q-- 1 perm 1f1f0000 32 -1 keyring _uid.32: 1/4
- 000004d3 I--Q-- 3 perm 1f1f0000 32 -1 keyring _uid_ses.32: empty
+ 00000001 I----- 39 perm 1f3f0000 0 0 keyring _uid_ses.0: 1/4
+ 00000002 I----- 2 perm 1f3f0000 0 0 keyring _uid.0: empty
+ 00000007 I----- 1 perm 1f3f0000 0 0 keyring _pid.1: empty
+ 0000018d I----- 1 perm 1f3f0000 0 0 keyring _pid.412: empty
+ 000004d2 I--Q-- 1 perm 1f3f0000 32 -1 keyring _uid.32: 1/4
+ 000004d3 I--Q-- 3 perm 1f3f0000 32 -1 keyring _uid_ses.32: empty
00000892 I--QU- 1 perm 1f000000 0 0 user metal:copper: 0
- 00000893 I--Q-N 1 35s 1f1f0000 0 0 user metal:silver: 0
- 00000894 I--Q-- 1 10h 001f0000 0 0 user metal:gold: 0
+ 00000893 I--Q-N 1 35s 1f3f0000 0 0 user metal:silver: 0
+ 00000894 I--Q-- 1 10h 003f0000 0 0 user metal:gold: 0
The flags are:
/sbin/request-key will be invoked in an attempt to obtain a key. The
callout_info string will be passed as an argument to the program.
+ See also Documentation/keys-request-key.txt.
+
The keyctl syscall functions are:
(*) Read the payload data from a key:
- key_serial_t keyctl(KEYCTL_READ, key_serial_t keyring, char *buffer,
- size_t buflen);
+ long keyctl(KEYCTL_READ, key_serial_t keyring, char *buffer,
+ size_t buflen);
This function attempts to read the payload data from the specified key
into the buffer. The process must have read permission on the key to
(*) Instantiate a partially constructed key.
- key_serial_t keyctl(KEYCTL_INSTANTIATE, key_serial_t key,
- const void *payload, size_t plen,
- key_serial_t keyring);
+ long keyctl(KEYCTL_INSTANTIATE, key_serial_t key,
+ const void *payload, size_t plen,
+ key_serial_t keyring);
If the kernel calls back to userspace to complete the instantiation of a
key, userspace should use this call to supply data for the key before the
(*) Negatively instantiate a partially constructed key.
- key_serial_t keyctl(KEYCTL_NEGATE, key_serial_t key,
- unsigned timeout, key_serial_t keyring);
+ long keyctl(KEYCTL_NEGATE, key_serial_t key,
+ unsigned timeout, key_serial_t keyring);
If the kernel calls back to userspace to complete the instantiation of a
key, userspace should use this call mark the key as negative before the
If successful, the key will have been attached to the default keyring for
implicitly obtained request-key keys, as set by KEYCTL_SET_REQKEY_KEYRING.
+ See also Documentation/keys-request-key.txt.
+
(*) When it is no longer required, the key should be released using:
It is safe to sleep in this method.
- (*) int (*duplicate)(struct key *key, const struct key *source);
-
- If this type of key can be duplicated, then this method should be
- provided. It is called to copy the payload attached to the source into the
- new key. The data length on the new key will have been updated and the
- quota adjusted already.
-
- This method will be called with the source key's semaphore read-locked to
- prevent its payload from being changed, thus RCU constraints need not be
- applied to the source key.
-
- This method does not have to lock the destination key in order to attach a
- payload. The fact that KEY_FLAG_INSTANTIATED is not set in key->flags
- prevents anything else from gaining access to the key.
-
- It is safe to sleep in this method.
-
-
(*) int (*update)(struct key *key, const void *data, size_t datalen);
If this type of key can be updated, then this method should be provided.