unix(4): Enhance LOCAL_CREDS_PERSISTENT ABI
As this ABI is still fresh (r367287), let's correct some mistakes now: - Version the structure to allow for future changes - Include sender's pid in control message structure - Use a distinct control message type from the cmsgcred / sockcred mess Discussed with: kib, markj, trasz Differential Revision: https://reviews.freebsd.org/D27084
This commit is contained in:
Conrad Meyer
parent
b1976ea14c
commit
ede4af47ae
@ -28,7 +28,7 @@
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.\" @(#)unix.4 8.1 (Berkeley) 6/9/93
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.\" $FreeBSD$
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.\"
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.Dd November 2, 2020
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.Dd November 9, 2020
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.Dt UNIX 4
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.Os
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.Sh NAME
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@ -295,6 +295,41 @@ except that socket credentials are passed on every read from a
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or
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.Dv SOCK_SEQPACKET
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socket, instead of just the first read.
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Additionally, the
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.Va msg_control
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field in the
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.Vt msghdr
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structure points to a buffer that contains a
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.Vt cmsghdr
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structure followed by a variable length
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.Vt sockcred2
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structure, defined in
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.In sys/socket.h
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as follows:
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.Bd -literal
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struct sockcred2 {
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int sc_version; /* version of this structure */
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pid_t sc_pid; /* PID of sending process */
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uid_t sc_uid; /* real user id */
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uid_t sc_euid; /* effective user id */
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gid_t sc_gid; /* real group id */
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gid_t sc_egid; /* effective group id */
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int sc_ngroups; /* number of supplemental groups */
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gid_t sc_groups[1]; /* variable length */
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};
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.Ed
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.Pp
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The current version is zero.
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.Pp
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The
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.Vt cmsghdr
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fields have the following values:
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.Bd -literal
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cmsg_len = CMSG_LEN(SOCKCRED2SIZE(ngroups))
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cmsg_level = SOL_SOCKET
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cmsg_type = SCM_CREDS2
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.Ed
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.Pp
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The
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.Dv LOCAL_CREDS
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and
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@ -644,6 +644,8 @@ bsd_to_linux_cmsg_type(int cmsg_type)
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return (LINUX_SCM_RIGHTS);
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case SCM_CREDS:
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return (LINUX_SCM_CREDENTIALS);
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case SCM_CREDS2:
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return (LINUX_SCM_CREDENTIALS);
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case SCM_TIMESTAMP:
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return (LINUX_SCM_TIMESTAMP);
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}
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@ -1508,6 +1510,7 @@ linux_recvmsg_common(struct thread *td, l_int s, struct l_msghdr *msghdr,
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{
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struct cmsghdr *cm;
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struct cmsgcred *cmcred;
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struct sockcred2 *scred;
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struct l_cmsghdr *linux_cmsg = NULL;
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struct l_ucred linux_ucred;
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socklen_t datalen, maxlen, outlen;
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@ -1631,6 +1634,16 @@ linux_recvmsg_common(struct thread *td, l_int s, struct l_msghdr *msghdr,
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datalen = sizeof(linux_ucred);
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break;
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case SCM_CREDS2:
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scred = data;
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bzero(&linux_ucred, sizeof(linux_ucred));
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linux_ucred.pid = scred->sc_pid;
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linux_ucred.uid = scred->sc_uid;
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linux_ucred.gid = scred->sc_gid;
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data = &linux_ucred;
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datalen = sizeof(linux_ucred);
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break;
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case SCM_TIMESTAMP:
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if (datalen != sizeof(struct timeval)) {
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error = EMSGSIZE;
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@ -308,7 +308,7 @@ static int unp_internalize(struct mbuf **, struct thread *);
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static void unp_internalize_fp(struct file *);
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static int unp_externalize(struct mbuf *, struct mbuf **, int);
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static int unp_externalize_fp(struct file *);
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static struct mbuf *unp_addsockcred(struct thread *, struct mbuf *);
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static struct mbuf *unp_addsockcred(struct thread *, struct mbuf *, int);
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static void unp_process_defers(void * __unused, int);
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static void
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@ -1043,7 +1043,8 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
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}
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if (unp2->unp_flags & UNP_WANTCRED_MASK)
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control = unp_addsockcred(td, control);
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control = unp_addsockcred(td, control,
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unp2->unp_flags);
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if (unp->unp_addr != NULL)
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from = (struct sockaddr *)unp->unp_addr;
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else
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@ -1102,8 +1103,8 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
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* SOCK_SEQPACKET (LOCAL_CREDS => WANTCRED_ONESHOT), or
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* forever (LOCAL_CREDS_PERSISTENT => WANTCRED_ALWAYS).
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*/
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control = unp_addsockcred(td, control, unp2->unp_flags);
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unp2->unp_flags &= ~UNP_WANTCRED_ONESHOT;
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control = unp_addsockcred(td, control);
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}
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/*
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@ -2383,34 +2384,58 @@ unp_internalize(struct mbuf **controlp, struct thread *td)
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}
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static struct mbuf *
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unp_addsockcred(struct thread *td, struct mbuf *control)
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unp_addsockcred(struct thread *td, struct mbuf *control, int mode)
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{
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struct mbuf *m, *n, *n_prev;
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struct sockcred *sc;
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const struct cmsghdr *cm;
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int ngroups;
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int i;
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int ngroups, i, cmsgtype;
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size_t ctrlsz;
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ngroups = MIN(td->td_ucred->cr_ngroups, CMGROUP_MAX);
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m = sbcreatecontrol(NULL, SOCKCREDSIZE(ngroups), SCM_CREDS, SOL_SOCKET);
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if (mode & UNP_WANTCRED_ALWAYS) {
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ctrlsz = SOCKCRED2SIZE(ngroups);
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cmsgtype = SCM_CREDS2;
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} else {
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ctrlsz = SOCKCREDSIZE(ngroups);
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cmsgtype = SCM_CREDS;
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}
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m = sbcreatecontrol(NULL, ctrlsz, cmsgtype, SOL_SOCKET);
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if (m == NULL)
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return (control);
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sc = (struct sockcred *) CMSG_DATA(mtod(m, struct cmsghdr *));
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sc->sc_uid = td->td_ucred->cr_ruid;
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sc->sc_euid = td->td_ucred->cr_uid;
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sc->sc_gid = td->td_ucred->cr_rgid;
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sc->sc_egid = td->td_ucred->cr_gid;
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sc->sc_ngroups = ngroups;
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for (i = 0; i < sc->sc_ngroups; i++)
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sc->sc_groups[i] = td->td_ucred->cr_groups[i];
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if (mode & UNP_WANTCRED_ALWAYS) {
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struct sockcred2 *sc;
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sc = (void *)CMSG_DATA(mtod(m, struct cmsghdr *));
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sc->sc_version = 0;
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sc->sc_pid = td->td_proc->p_pid;
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sc->sc_uid = td->td_ucred->cr_ruid;
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sc->sc_euid = td->td_ucred->cr_uid;
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sc->sc_gid = td->td_ucred->cr_rgid;
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sc->sc_egid = td->td_ucred->cr_gid;
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sc->sc_ngroups = ngroups;
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for (i = 0; i < sc->sc_ngroups; i++)
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sc->sc_groups[i] = td->td_ucred->cr_groups[i];
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} else {
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struct sockcred *sc;
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sc = (void *)CMSG_DATA(mtod(m, struct cmsghdr *));
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sc->sc_uid = td->td_ucred->cr_ruid;
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sc->sc_euid = td->td_ucred->cr_uid;
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sc->sc_gid = td->td_ucred->cr_rgid;
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sc->sc_egid = td->td_ucred->cr_gid;
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sc->sc_ngroups = ngroups;
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for (i = 0; i < sc->sc_ngroups; i++)
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sc->sc_groups[i] = td->td_ucred->cr_groups[i];
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}
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/*
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* Unlink SCM_CREDS control messages (struct cmsgcred), since just
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* created SCM_CREDS control message (struct sockcred) has another
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* format.
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*/
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if (control != NULL)
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if (control != NULL && cmsgtype == SCM_CREDS)
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for (n = control, n_prev = NULL; n != NULL;) {
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cm = mtod(n, struct cmsghdr *);
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if (cm->cmsg_level == SOL_SOCKET &&
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@ -510,7 +510,7 @@ struct cmsgcred {
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};
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/*
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* Socket credentials.
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* Socket credentials (LOCAL_CREDS).
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*/
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struct sockcred {
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uid_t sc_uid; /* real user id */
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@ -527,6 +527,22 @@ struct sockcred {
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#define SOCKCREDSIZE(ngrps) \
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(sizeof(struct sockcred) + (sizeof(gid_t) * ((ngrps) - 1)))
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/*
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* Socket credentials (LOCAL_CREDS_PERSISTENT).
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*/
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struct sockcred2 {
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int sc_version; /* version of this structure */
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pid_t sc_pid; /* PID of sending process */
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uid_t sc_uid; /* real user id */
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uid_t sc_euid; /* effective user id */
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gid_t sc_gid; /* real group id */
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gid_t sc_egid; /* effective group id */
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int sc_ngroups; /* number of supplemental groups */
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gid_t sc_groups[1]; /* variable length */
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};
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#define SOCKCRED2SIZE(ngrps) \
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(sizeof(struct sockcred2) + (sizeof(gid_t) * ((ngrps) - 1)))
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#endif /* __BSD_VISIBLE */
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/* given pointer to struct cmsghdr, return pointer to data */
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@ -571,6 +587,7 @@ struct sockcred {
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#define SCM_REALTIME 0x05 /* timestamp (struct timespec) */
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#define SCM_MONOTONIC 0x06 /* timestamp (struct timespec) */
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#define SCM_TIME_INFO 0x07 /* timestamp info */
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#define SCM_CREDS2 0x08 /* process creds (struct sockcred2) */
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struct sock_timestamp_info {
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__uint32_t st_info_flags;
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