getpeereid (3) - Linux Manuals
getpeereid: get the effective credentials of a UNIX-domain peer
getpeereid - get the effective credentials of a UNIX-domain peer
SYNOPSISIn sys/types.h In bsd/unistd.h Ft int Fn getpeereid int s uid_t *euid gid_t *egid
DESCRIPTIONThe 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 NOTESOn Fx , Fn getpeereid is implemented in terms of the LOCAL_PEERCRED unix(4) socket option.
RETURN VALUESRv -std getpeereid
ERRORSThe 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.
HISTORYThe Fn getpeereid function appeared in Fx 4.6 .