getpeereid (3) - Linux Manuals

getpeereid: get the effective credentials of a UNIX-domain peer

NAME

getpeereid - get the effective credentials of a UNIX-domain peer

LIBRARY

Lb libbsd

SYNOPSIS

In sys/types.h In bsd/unistd.h Ft int Fn getpeereid int s uid_t *euid gid_t *egid

DESCRIPTION

The Fn getpeereid function returns the effective user and group IDs of the peer connected to a UNIX socket. The argument Fa s must be a UNIX socket (unix(4) ) of type SOCK_STREAM on which either connect(2) or listen(2) have been called. The effective used ID is placed in Fa euid , and the effective group ID in Fa egid .

The credentials returned to the listen(2) caller are those of its peer at the time it called connect(2); the credentials returned to the connect(2) caller are those of its peer at the time it called listen(2). This mechanism is reliable; there is no way for either side to influence the credentials returned to its peer except by calling the appropriate system call (i.e., either connect(2) or listen(2)) under different effective credentials.

One common use of this routine is for a UNIX server to verify the credentials of its client. Likewise, the client can verify the credentials of the server.

IMPLEMENTATION NOTES

On Fx , Fn getpeereid is implemented in terms of the LOCAL_PEERCRED unix(4) socket option.

RETURN VALUES

Rv -std getpeereid

ERRORS

The Fn getpeereid function fails if:

Bq Er EBADF

The argument Fa s is not a valid descriptor.

Bq Er ENOTSOCK

The argument Fa s is a file, not a socket.

Bq Er ENOTCONN

The argument Fa s does not refer to a socket on which connect(2) or listen(2) have been called.

Bq Er EINVAL

The argument Fa s does not refer to a socket of type SOCK_STREAM or the kernel returned invalid data.

HISTORY

The Fn getpeereid function appeared in Fx 4.6 .