Name
sd_pid_get_owner_uid, sd_pid_get_session, sd_pid_get_user_unit, sd_pid_get_unit, sd_pid_get_machine_name, sd_pid_get_slice, sd_pid_get_user_slice, sd_pid_get_cgroup, sd_pidfd_get_owner_uid, sd_pidfd_get_session, sd_pidfd_get_user_unit, sd_pidfd_get_unit, sd_pidfd_get_machine_name, sd_pidfd_get_slice, sd_pidfd_get_user_slice, sd_pidfd_get_cgroup, sd_peer_get_owner_uid, sd_peer_get_session, sd_peer_get_user_unit, sd_peer_get_unit, sd_peer_get_machine_name, sd_peer_get_slice, sd_peer_get_user_slice, sd_peer_get_cgroup — Determine the owner uid of the user unit or session,
or the session, user unit, system unit, container/VM or slice that
a specific PID or socket peer belongs to
Synopsis
#include <systemd/sd-login.h>
int sd_pid_get_owner_uid( | pid_t pid, |
| uid_t *uid) ; |
int sd_pid_get_session( | pid_t pid, |
| char **session) ; |
int sd_pid_get_user_unit( | pid_t pid, |
| char **unit) ; |
int sd_pid_get_unit( | pid_t pid, |
| char **unit) ; |
int sd_pid_get_machine_name( | pid_t pid, |
| char **name) ; |
int sd_pid_get_slice( | pid_t pid, |
| char **slice) ; |
int sd_pid_get_user_slice( | pid_t pid, |
| char **slice) ; |
int sd_pid_get_cgroup( | pid_t pid, |
| char **cgroup) ; |
int sd_pidfd_get_owner_uid( | int pidfd, |
| uid_t *uid) ; |
int sd_pidfd_get_session( | int pidfd, |
| char **session) ; |
int sd_pidfd_get_user_unit( | int pidfd, |
| char **unit) ; |
int sd_pidfd_get_unit( | int pidfd, |
| char **unit) ; |
int sd_pidfd_get_machine_name( | int pidfd, |
| char **name) ; |
int sd_pidfd_get_slice( | int pidfd, |
| char **slice) ; |
int sd_pidfd_get_user_slice( | int pidfd, |
| char **slice) ; |
int sd_pidfd_get_cgroup( | int pidfd, |
| char **cgroup) ; |
int sd_peer_get_owner_uid( | int fd, |
| uid_t *uid) ; |
int sd_peer_get_session( | int fd, |
| char **session) ; |
int sd_peer_get_user_unit( | int fd, |
| char **unit) ; |
int sd_peer_get_unit( | int fd, |
| char **unit) ; |
int sd_peer_get_machine_name( | int fd, |
| char **name) ; |
int sd_peer_get_slice( | int fd, |
| char **slice) ; |
int sd_peer_get_user_slice( | int fd, |
| char **slice) ; |
int sd_peer_get_cgroup( | int fd, |
| char **cgroup) ; |
Description
sd_pid_get_owner_uid()
may be used to
determine the Unix UID (user identifier) which owns the login
session or systemd user unit of a process identified by the
specified PID. For processes which are not part of a login session
and not managed by a user manager, this function will fail with
-ENODATA
.
sd_pid_get_session()
may be used to
determine the login session identifier of a process identified by
the specified process identifier. The session identifier is a
short string, suitable for usage in file system paths. Please
note the login session may be limited to a stub process or two.
User processes may instead be started from their systemd user
manager, e.g. GUI applications started using DBus activation, as
well as service processes which are shared between multiple logins
of the same user. For processes which are not part of a login
session, this function will fail with -ENODATA
.
The returned string needs to be freed with the libc free(3)
call after use.
sd_pid_get_user_unit()
may be used to
determine the systemd user unit (i.e. user service or scope unit)
identifier of a process identified by the specified PID. The
unit name is a short string, suitable for usage in file system
paths. For processes which are not managed by a user manager, this
function will fail with -ENODATA
. The
returned string needs to be freed with the libc free(3)
call after use.
sd_pid_get_unit()
may be used to
determine the systemd system unit (i.e. system service or scope
unit) identifier of a process identified by the specified PID. The
unit name is a short string, suitable for usage in file system
paths. Note that not all processes are part of a system
unit/service. For processes not being part of a systemd system
unit, this function will fail with -ENODATA
.
(More specifically, this call will not work for kernel threads.)
The returned string needs to be freed with the libc free(3)
call after use.
sd_pid_get_machine_name()
may be used
to determine the name of the VM or container is a member of. The
machine name is a short string, suitable for usage in file system
paths. The returned string needs to be freed with the libc
free(3)
call after use. For processes not part of a VM or container, this
function fails with -ENODATA
.
sd_pid_get_slice()
may be used to
determine the slice unit the process is a member of. See
systemd.slice(5)
for details about slices. The returned string needs to be freed
with the libc
free(3)
call after use.
Similarly, sd_pid_get_user_slice()
returns the user slice (as managed by the user's systemd instance)
of a process.
sd_pid_get_cgroup()
returns the control
group path of the specified process, relative to the root of the
hierarchy. Returns the path without trailing slash, except for
processes located in the root control group, where "/" is
returned. To find the actual control group path in the file system,
the returned path needs to be prefixed with
/sys/fs/cgroup/
(if the unified control group
setup is used), or
/sys/fs/cgroup/HIERARCHY
/
(if the legacy multi-hierarchy control group setup is used).
If the pid
parameter of any of these
functions is passed as 0, the operation is executed for the
calling process.
The sd_pidfd_get_owner_uid()
,
sd_pidfd_get_session()
,
sd_pidfd_get_user_unit()
,
sd_pidfd_get_unit()
,
sd_pidfd_get_machine_name()
,
sd_pidfd_get_slice()
,
sd_pidfd_get_user_slice()
and
sd_pidfd_get_cgroup()
calls operate similarly to their PID counterparts, but accept a
PIDFD
instead of a PID
, which means they are not subject to recycle
race conditions as the process is pinned by the file descriptor during the whole duration of the invocation.
Note that these require a kernel that supports PIDFD
. A suitable file descriptor may be
acquired via
pidfd_open(2).
The sd_peer_get_owner_uid()
,
sd_peer_get_session()
,
sd_peer_get_user_unit()
,
sd_peer_get_unit()
,
sd_peer_get_machine_name()
,
sd_peer_get_slice()
,
sd_peer_get_user_slice()
and
sd_peer_get_cgroup()
calls operate similarly to their PID counterparts, but accept a
connected AF_UNIX
socket and retrieve information about the connected peer process.
Note that these fields are retrieved via /proc/
, and hence are not suitable for
authorization purposes, as they are subject to races.
Return Value
On success, these calls return 0 or a positive integer. On failure, these calls return a negative
errno-style error code.
Errors
Returned errors may indicate the following problems:
-ESRCH
The specified PID does not refer to a running process.
-EBADF
The specified socket file descriptor was invalid.
-ENODATA
The given field is not specified for the described process or peer.
-EINVAL
An input parameter was invalid (out of range, or NULL
, where
that is not accepted).
-ENOMEM
Memory allocation failed.
Notes
Functions described here are available as a shared
library, which can be compiled against and linked to with the
libsystemd
pkg-config(1)
file.
Note that the login session identifier as
returned by sd_pid_get_session()
is completely unrelated to the process session
identifier as returned by
getsid(2).
History
sd_peer_get_cgroup()
,
sd_peer_get_machine_name()
,
sd_peer_get_owner_uid()
,
sd_peer_get_session()
,
sd_peer_get_slice()
,
sd_peer_get_unit()
,
sd_peer_get_user_slice()
,
sd_peer_get_user_unit()
,
sd_pid_get_cgroup()
,
sd_pid_get_machine_name()
,
sd_pid_get_owner_uid()
,
sd_pid_get_session()
,
sd_pid_get_slice()
,
sd_pid_get_unit()
,
sd_pid_get_user_slice()
, and
sd_pid_get_user_unit()
were added in version 236.
sd_pidfd_get_owner_uid()
,
sd_pidfd_get_session()
,
sd_pidfd_get_user_unit()
,
sd_pidfd_get_unit()
,
sd_pidfd_get_machine_name()
,
sd_pidfd_get_slice()
,
sd_pidfd_get_user_slice()
, and
sd_pidfd_get_cgroup()
were added in version 253.