diff --git a/src/header/sys_socket/mod.rs b/src/header/sys_socket/mod.rs
--- a/src/header/sys_socket/mod.rs
+++ b/src/header/sys_socket/mod.rs
@@ -5,7 +5,7 @@
 use core::{mem, ptr};
 
 use crate::{
-    error::ResultExt,
+    error::{Errno, ResultExt},
     header::{bits_iovec::iovec, bits_safamily_t::sa_family_t, bits_socklen_t::socklen_t},
     platform::{
         PalSocket, Sys,
@@ -236,6 +236,48 @@
         socket,
         address,
         address_len
+    )
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn getpeereid(socket: c_int, euid: *mut uid_t, egid: *mut gid_t) -> c_int {
+    trace_expr!(
+        (|| {
+            if euid.is_null() || egid.is_null() {
+                return Err(Errno(crate::header::errno::EFAULT));
+            }
+
+            let mut cred = ucred {
+                pid: 0,
+                uid: 0,
+                gid: 0,
+            };
+            let mut len = mem::size_of::<ucred>() as socklen_t;
+            unsafe {
+                Sys::getsockopt(
+                    socket,
+                    constants::SOL_SOCKET,
+                    constants::SO_PEERCRED,
+                    &mut cred as *mut ucred as *mut c_void,
+                    &mut len,
+                )?;
+            }
+
+            if (len as usize) < mem::size_of::<ucred>() {
+                return Err(Errno(crate::header::errno::EINVAL));
+            }
+
+            unsafe {
+                *euid = cred.uid;
+                *egid = cred.gid;
+            }
+            Ok(0)
+        })()
+        .or_minus_one_errno(),
+        "getpeereid({}, {:p}, {:p})",
+        socket,
+        euid,
+        egid
     )
 }
 
diff --git a/tests/Makefile.tests.mk b/tests/Makefile.tests.mk
--- a/tests/Makefile.tests.mk
+++ b/tests/Makefile.tests.mk
@@ -137,6 +137,8 @@
 	string/stpcpy \
 	string/stpncpy \
 	strings \
+	sys_socket/passcred \
+	sys_socket/peercred \
 	sys_socket/recv \
 	sys_socket/recvfrom \
 	sys_socket/unixrecv \
diff --git a/tests/sys_socket/peercred.c b/tests/sys_socket/peercred.c
new file mode 100644
--- /dev/null
+++ b/tests/sys_socket/peercred.c
@@ -0,0 +1,33 @@
+#include <assert.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "test_helpers.h"
+
+int main(void)
+{
+    int sv[2];
+    int status = socketpair(AF_UNIX, SOCK_STREAM, 0, sv);
+    ERROR_IF(socketpair, status, == -1);
+
+    struct ucred cred;
+    socklen_t len = sizeof(cred);
+    status = getsockopt(sv[0], SOL_SOCKET, SO_PEERCRED, &cred, &len);
+    ERROR_IF(getsockopt, status, == -1);
+    assert(len == sizeof(cred));
+    assert(cred.uid == getuid());
+    assert(cred.gid == getgid());
+    assert(cred.pid > 0);
+
+    uid_t euid;
+    gid_t egid;
+    status = getpeereid(sv[0], &euid, &egid);
+    ERROR_IF(getpeereid, status, == -1);
+    assert(euid == getuid());
+    assert(egid == getgid());
+
+    close(sv[0]);
+    close(sv[1]);
+    return 0;
+}
diff --git a/tests/sys_socket/passcred.c b/tests/sys_socket/passcred.c
new file mode 100644
--- /dev/null
+++ b/tests/sys_socket/passcred.c
@@ -0,0 +1,62 @@
+#include <assert.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "test_helpers.h"
+
+int main(void)
+{
+    int sv[2];
+    int status = socketpair(AF_UNIX, SOCK_STREAM, 0, sv);
+    ERROR_IF(socketpair, status, == -1);
+
+    int one = 1;
+    status = setsockopt(sv[1], SOL_SOCKET, SO_PASSCRED, &one, sizeof(one));
+    ERROR_IF(setsockopt, status, == -1);
+
+    const char payload[] = "x";
+    ssize_t sent = send(sv[0], payload, sizeof(payload), 0);
+    ERROR_IF(send, sent, == -1);
+    assert(sent == (ssize_t)sizeof(payload));
+
+    char byte = '\0';
+    struct iovec iov = {
+        .iov_base = &byte,
+        .iov_len = sizeof(byte),
+    };
+    union {
+        char buf[CMSG_SPACE(sizeof(struct ucred))];
+        struct cmsghdr align;
+    } control;
+    memset(&control, 0, sizeof(control));
+
+    struct msghdr msg = {
+        .msg_name = NULL,
+        .msg_namelen = 0,
+        .msg_iov = &iov,
+        .msg_iovlen = 1,
+        .msg_control = control.buf,
+        .msg_controllen = sizeof(control.buf),
+        .msg_flags = 0,
+    };
+
+    ssize_t recvd = recvmsg(sv[1], &msg, 0);
+    ERROR_IF(recvmsg, recvd, == -1);
+    assert(recvd == (ssize_t)sizeof(payload));
+    assert(byte == 'x');
+
+    struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+    assert(cmsg != NULL);
+    assert(cmsg->cmsg_level == SOL_SOCKET);
+    assert(cmsg->cmsg_type == SCM_CREDENTIALS);
+    struct ucred *cred = (struct ucred *)CMSG_DATA(cmsg);
+    assert(cred->uid == getuid());
+    assert(cred->gid == getgid());
+    assert(cred->pid > 0);
+
+    close(sv[0]);
+    close(sv[1]);
+    return 0;
+}