session-keyring - Session shared process keyring
The session keyring
is a keyring used to anchor keys on behalf of a
process. It is typically created by the pam_keyinit
module when a user
logs in and a link will be added that refers to the user keyring
A special serial number value, KEY_SPEC_SESSION_KEYRING
, is defined that
can be used in lieu of the calling process's session keyring's actual serial
From the keyctl utility, ' @s
' can be used instead of a numeric key ID in
much the same way.
A process's session keyring is inherited across clone(), fork() and vfork() and
is retained across execve() - even when the target executable is setuid or
setgid. The session keyring will be destroyed when the last process that
refers to it exits.
If a process doesn't have a session keyring when it is accessed, then, under
certain circumstances, the user session keyring
will be attached as the
session keyring and under others a new session keyring will be created.
The keyutils library provides a number of special operations for manipulating
- This operation allows the caller to change their session
keyring. The caller can join an existing keyring by name, create a new
keyring of the name given or ask the kernel to create a new session
keyring with the name "_ses".
- This operation allows the caller to set the parent
process's session keyring to the same as their own. For this to succeed,
the parent process must have identical security attributes and must be
These operations are also exposed through the keyctl utility as:
session - [<prog> <arg1> <arg2> ...]
session <name> [<prog> <arg1> <arg2>