SysV IPC: provide in-kernel helpers to obtain ipcs(8)-like information

PR:	278949
Reviewed by:	markj
Tested by:	Ricardo Branco <[email protected]>
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D45175

Author: kostikbel

sys/kern/sysv_msg.c

@@ -1477,6 +1477,40 @@ sysctl_msqids(SYSCTL_HANDLER_ARGS)
 	return (error);
 }
 
+int
+kern_get_msqids(struct thread *td, struct msqid_kernel **res, size_t *sz)
+{
+	struct msqid_kernel *pmsqk;
+	struct prison *pr, *rpr;
+	int i, mi;
+
+	*sz = mi = msginfo.msgmni;
+	if (res == NULL)
+		return (0);
+
+	pr = td->td_ucred->cr_prison;
+	rpr = msg_find_prison(td->td_ucred);
+	*res = malloc(sizeof(struct msqid_kernel) * mi, M_TEMP, M_WAITOK);
+	for (i = 0; i < mi; i++) {
+		pmsqk = &(*res)[i];
+		mtx_lock(&msq_mtx);
+		if (msqids[i].u.msg_qbytes == 0 || rpr == NULL ||
+		    msq_prison_cansee(rpr, &msqids[i]) != 0)
+			bzero(pmsqk, sizeof(*pmsqk));
+		else {
+			*pmsqk = msqids[i];
+			if (pmsqk->cred->cr_prison != pr)
+				pmsqk->u.msg_perm.key = IPC_PRIVATE;
+		}
+		mtx_unlock(&msq_mtx);
+		pmsqk->u.__msg_first = NULL;
+		pmsqk->u.__msg_last = NULL;
+		pmsqk->label = NULL;
+		pmsqk->cred = NULL;
+	}
+	return (0);
+}
+
 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmax, CTLFLAG_RD, &msginfo.msgmax, 0,
     "Maximum message size");
 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmni, CTLFLAG_RDTUN, &msginfo.msgmni, 0,

sys/kern/sysv_sem.c

@@ -1574,6 +1574,39 @@ sysctl_sema(SYSCTL_HANDLER_ARGS)
 	return (error);
 }
 
+int
+kern_get_sema(struct thread *td, struct semid_kernel **res, size_t *sz)
+{
+	struct prison *pr, *rpr;
+	struct semid_kernel *psemak;
+	int i, mi;
+
+	*sz = mi = seminfo.semmni;
+	if (res == NULL)
+		return (0);
+
+	pr = td->td_ucred->cr_prison;
+	rpr = sem_find_prison(td->td_ucred);
+	*res = malloc(sizeof(struct semid_kernel) * mi, M_TEMP, M_WAITOK);
+	for (i = 0; i < mi; i++) {
+		psemak = &(*res)[i];
+		mtx_lock(&sema_mtx[i]);
+		if ((sema[i].u.sem_perm.mode & SEM_ALLOC) == 0 ||
+		    rpr == NULL || sem_prison_cansee(rpr, &sema[i]) != 0)
+			bzero(psemak, sizeof(*psemak));
+		else {
+			*psemak = sema[i];
+			if (psemak->cred->cr_prison != pr)
+				psemak->u.sem_perm.key = IPC_PRIVATE;
+		}
+		mtx_unlock(&sema_mtx[i]);
+		psemak->u.__sem_base = NULL;
+		psemak->label = NULL;
+		psemak->cred = NULL;
+	}
+	return (0);
+}
+
 static int
 sem_prison_check(void *obj, void *data)
 {

sys/kern/sysv_shm.c

@@ -1089,6 +1089,42 @@ sysctl_shmsegs(SYSCTL_HANDLER_ARGS)
 	return (error);
 }
 
+int
+kern_get_shmsegs(struct thread *td, struct shmid_kernel **res, size_t *sz)
+{
+	struct shmid_kernel *pshmseg;
+	struct prison *pr, *rpr;
+	int i;
+
+	SYSVSHM_LOCK();
+	*sz = shmalloced;
+	if (res == NULL)
+		goto out;
+
+	pr = td->td_ucred->cr_prison;
+	rpr = shm_find_prison(td->td_ucred);
+	*res = malloc(sizeof(struct shmid_kernel) * shmalloced, M_TEMP,
+	    M_WAITOK);
+	for (i = 0; i < shmalloced; i++) {
+		pshmseg = &(*res)[i];
+		if ((shmsegs[i].u.shm_perm.mode & SHMSEG_ALLOCATED) == 0 ||
+		    rpr == NULL || shm_prison_cansee(rpr, &shmsegs[i]) != 0) {
+			bzero(pshmseg, sizeof(*pshmseg));
+			pshmseg->u.shm_perm.mode = SHMSEG_FREE;
+		} else {
+			*pshmseg = shmsegs[i];
+			if (pshmseg->cred->cr_prison != pr)
+				pshmseg->u.shm_perm.key = IPC_PRIVATE;
+		}
+		pshmseg->object = NULL;
+		pshmseg->label = NULL;
+		pshmseg->cred = NULL;
+	}
+out:
+	SYSVSHM_UNLOCK();
+	return (0);
+}
+
 static int
 shm_prison_check(void *obj, void *data)
 {

sys/sys/msg.h

@@ -152,6 +152,9 @@ struct msqid_kernel {
 #ifdef _KERNEL
 extern struct msginfo	msginfo;
 
+int	kern_get_msqids(struct thread *td, struct msqid_kernel **res,
+	    size_t *sz);
+
 #else /* _KERNEL */
 
 __BEGIN_DECLS

sys/sys/sem.h

@@ -142,6 +142,9 @@ extern struct seminfo	seminfo;
  */
 void	semexit(struct proc *p);
 
+int	kern_get_sema(struct thread *td, struct semid_kernel **res,
+	    size_t *sz);
+
 #else /* !_KERNEL */
 
 __BEGIN_DECLS

sys/sys/shm.h

@@ -158,6 +158,8 @@ extern struct shminfo	shminfo;
 
 void	shmexit(struct vmspace *);
 void	shmfork(struct proc *, struct proc *);
+int	kern_get_shmsegs(struct thread *td, struct shmid_kernel **res,
+	    size_t *sz);
 
 #else /* !_KERNEL */