sd_pid_get_owner_uid

elogind
sd_pid_get_owner_uid 3
sd_pid_get_owner_uid sd_pid_get_session 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_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

    #include <elogind/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_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_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 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. 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_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_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

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.

## See Also

elogind 8, sd-login 3, sd_session_is_active 3, getsid 2