diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -109,7 +109,8 @@
 static void	fdunused(struct filedesc *fdp, int fd);
 static void	fdused(struct filedesc *fdp, int fd);
 static int	fget_unlocked_seq(struct thread *td, int fd,
-		    cap_rights_t *needrightsp, struct file **fpp, seqc_t *seqp);
+		    const cap_rights_t *needrightsp, struct file **fpp,
+		    seqc_t *seqp);
 static int	getmaxfd(struct thread *td);
 static u_long	*filecaps_copy_prep(const struct filecaps *src);
 static void	filecaps_copy_finish(const struct filecaps *src,
@@ -2877,7 +2878,7 @@
 }
 
 int
-fget_cap_noref(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
+fget_cap_noref(struct filedesc *fdp, int fd, const cap_rights_t *needrightsp,
     struct file **fpp, struct filecaps *havecapsp)
 {
 	struct filedescent *fde;
@@ -2910,7 +2911,7 @@
 
 #ifdef CAPABILITIES
 int
-fget_cap(struct thread *td, int fd, cap_rights_t *needrightsp,
+fget_cap(struct thread *td, int fd, const cap_rights_t *needrightsp,
     struct file **fpp, struct filecaps *havecapsp)
 {
 	struct filedesc *fdp = td->td_proc->p_fd;
@@ -2950,7 +2951,7 @@
 }
 #else
 int
-fget_cap(struct thread *td, int fd, cap_rights_t *needrightsp,
+fget_cap(struct thread *td, int fd, const cap_rights_t *needrightsp,
     struct file **fpp, struct filecaps *havecapsp)
 {
 	int error;
@@ -3221,7 +3222,7 @@
  */
 #ifdef CAPABILITIES
 static int
-fget_unlocked_seq(struct thread *td, int fd, cap_rights_t *needrightsp,
+fget_unlocked_seq(struct thread *td, int fd, const cap_rights_t *needrightsp,
     struct file **fpp, seqc_t *seqp)
 {
 	struct filedesc *fdp;
@@ -3277,7 +3278,7 @@
 }
 #else
 static int
-fget_unlocked_seq(struct thread *td, int fd, cap_rights_t *needrightsp,
+fget_unlocked_seq(struct thread *td, int fd, const cap_rights_t *needrightsp,
     struct file **fpp, seqc_t *seqp __unused)
 {
 	struct filedesc *fdp;
@@ -3320,7 +3321,7 @@
  * racing with itself.
  */
 int
-fget_unlocked(struct thread *td, int fd, cap_rights_t *needrightsp,
+fget_unlocked(struct thread *td, int fd, const cap_rights_t *needrightsp,
     struct file **fpp)
 {
 	struct filedesc *fdp;
@@ -3389,7 +3390,7 @@
  */
 #ifdef	CAPABILITIES
 int
-fget_only_user(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
+fget_only_user(struct filedesc *fdp, int fd, const cap_rights_t *needrightsp,
     struct file **fpp)
 {
 	const struct filedescent *fde;
@@ -3419,7 +3420,7 @@
 }
 #else
 int
-fget_only_user(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
+fget_only_user(struct filedesc *fdp, int fd, const cap_rights_t *needrightsp,
     struct file **fpp)
 {
 	struct file *fp;
@@ -3455,7 +3456,7 @@
  */
 static __inline int
 _fget(struct thread *td, int fd, struct file **fpp, int flags,
-    cap_rights_t *needrightsp)
+    const cap_rights_t *needrightsp)
 {
 	struct file *fp;
 	int error;
@@ -3501,15 +3502,15 @@
 }
 
 int
-fget(struct thread *td, int fd, cap_rights_t *rightsp, struct file **fpp)
+fget(struct thread *td, int fd, const cap_rights_t *rightsp, struct file **fpp)
 {
 
 	return (_fget(td, fd, fpp, 0, rightsp));
 }
 
 int
-fget_mmap(struct thread *td, int fd, cap_rights_t *rightsp, vm_prot_t *maxprotp,
-    struct file **fpp)
+fget_mmap(struct thread *td, int fd, const cap_rights_t *rightsp,
+    vm_prot_t *maxprotp, struct file **fpp)
 {
 	int error;
 #ifndef CAPABILITIES
@@ -3552,22 +3553,24 @@
 }
 
 int
-fget_read(struct thread *td, int fd, cap_rights_t *rightsp, struct file **fpp)
+fget_read(struct thread *td, int fd, const cap_rights_t *rightsp,
+    struct file **fpp)
 {
 
 	return (_fget(td, fd, fpp, FREAD, rightsp));
 }
 
 int
-fget_write(struct thread *td, int fd, cap_rights_t *rightsp, struct file **fpp)
+fget_write(struct thread *td, int fd, const cap_rights_t *rightsp,
+    struct file **fpp)
 {
 
 	return (_fget(td, fd, fpp, FWRITE, rightsp));
 }
 
 int
-fget_fcntl(struct thread *td, int fd, cap_rights_t *rightsp, int needfcntl,
-    struct file **fpp)
+fget_fcntl(struct thread *td, int fd, const cap_rights_t *rightsp,
+    int needfcntl, struct file **fpp)
 {
 #ifndef CAPABILITIES
 	return (fget_unlocked(td, fd, rightsp, fpp));
@@ -3605,7 +3608,7 @@
  * XXX: what about the unused flags ?
  */
 static __inline int
-_fgetvp(struct thread *td, int fd, int flags, cap_rights_t *needrightsp,
+_fgetvp(struct thread *td, int fd, int flags, const cap_rights_t *needrightsp,
     struct vnode **vpp)
 {
 	struct file *fp;
@@ -3627,14 +3630,15 @@
 }
 
 int
-fgetvp(struct thread *td, int fd, cap_rights_t *rightsp, struct vnode **vpp)
+fgetvp(struct thread *td, int fd, const cap_rights_t *rightsp,
+    struct vnode **vpp)
 {
 
 	return (_fgetvp(td, fd, 0, rightsp, vpp));
 }
 
 int
-fgetvp_rights(struct thread *td, int fd, cap_rights_t *needrightsp,
+fgetvp_rights(struct thread *td, int fd, const cap_rights_t *needrightsp,
     struct filecaps *havecaps, struct vnode **vpp)
 {
 	struct filecaps caps;
@@ -3666,14 +3670,16 @@
 }
 
 int
-fgetvp_read(struct thread *td, int fd, cap_rights_t *rightsp, struct vnode **vpp)
+fgetvp_read(struct thread *td, int fd, const cap_rights_t *rightsp,
+    struct vnode **vpp)
 {
 
 	return (_fgetvp(td, fd, FREAD, rightsp, vpp));
 }
 
 int
-fgetvp_exec(struct thread *td, int fd, cap_rights_t *rightsp, struct vnode **vpp)
+fgetvp_exec(struct thread *td, int fd, const cap_rights_t *rightsp,
+    struct vnode **vpp)
 {
 
 	return (_fgetvp(td, fd, FEXEC, rightsp, vpp));
@@ -3681,7 +3687,7 @@
 
 #ifdef notyet
 int
-fgetvp_write(struct thread *td, int fd, cap_rights_t *rightsp,
+fgetvp_write(struct thread *td, int fd, const cap_rights_t *rightsp,
     struct vnode **vpp)
 {
 
diff --git a/sys/kern/sys_procdesc.c b/sys/kern/sys_procdesc.c
--- a/sys/kern/sys_procdesc.c
+++ b/sys/kern/sys_procdesc.c
@@ -118,7 +118,7 @@
  * died.
  */
 int
-procdesc_find(struct thread *td, int fd, cap_rights_t *rightsp,
+procdesc_find(struct thread *td, int fd, const cap_rights_t *rightsp,
     struct proc **p)
 {
 	struct procdesc *pd;
@@ -165,7 +165,8 @@
  * Retrieve the PID associated with a process descriptor.
  */
 int
-kern_pdgetpid(struct thread *td, int fd, cap_rights_t *rightsp, pid_t *pidp)
+kern_pdgetpid(struct thread *td, int fd, const cap_rights_t *rightsp,
+    pid_t *pidp)
 {
 	struct file *fp;
 	int error;
diff --git a/sys/kern/uipc_mqueue.c b/sys/kern/uipc_mqueue.c
--- a/sys/kern/uipc_mqueue.c
+++ b/sys/kern/uipc_mqueue.c
@@ -2169,13 +2169,14 @@
 	return (error);
 }
 
-typedef int (*_fgetf)(struct thread *, int, cap_rights_t *, struct file **);
+typedef int (*_fgetf)(struct thread *, int, const cap_rights_t *,
+    struct file **);
 
 /*
  * Get message queue by giving file slot
  */
 static int
-_getmq(struct thread *td, int fd, cap_rights_t *rightsp, _fgetf func,
+_getmq(struct thread *td, int fd, const cap_rights_t *rightsp, _fgetf func,
        struct file **fpp, struct mqfs_node **ppn, struct mqueue **pmq)
 {
 	struct mqfs_node *pn;
diff --git a/sys/kern/uipc_sem.c b/sys/kern/uipc_sem.c
--- a/sys/kern/uipc_sem.c
+++ b/sys/kern/uipc_sem.c
@@ -123,8 +123,8 @@
 		    semid_t *semidp, mode_t mode, unsigned int value,
 		    int flags, int compat32);
 static void	ksem_drop(struct ksem *ks);
-static int	ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp,
-    struct file **fpp);
+static int	ksem_get(struct thread *td, semid_t id,
+		    const cap_rights_t *rightsp, struct file **fpp);
 static struct ksem *ksem_hold(struct ksem *ks);
 static void	ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks);
 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv);
@@ -587,7 +587,7 @@
 }
 
 static int
-ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp,
+ksem_get(struct thread *td, semid_t id, const cap_rights_t *rightsp,
     struct file **fpp)
 {
 	struct ksem *ks;
diff --git a/sys/kern/uipc_syscalls.c b/sys/kern/uipc_syscalls.c
--- a/sys/kern/uipc_syscalls.c
+++ b/sys/kern/uipc_syscalls.c
@@ -85,7 +85,7 @@
  * A reference on the file entry is held upon returning.
  */
 int
-getsock_cap(struct thread *td, int fd, cap_rights_t *rightsp,
+getsock_cap(struct thread *td, int fd, const cap_rights_t *rightsp,
     struct file **fpp, struct filecaps *havecapsp)
 {
 	struct file *fp;
@@ -105,7 +105,8 @@
 }
 
 int
-getsock(struct thread *td, int fd, cap_rights_t *rightsp, struct file **fpp)
+getsock(struct thread *td, int fd, const cap_rights_t *rightsp,
+    struct file **fpp)
 {
 	struct file *fp;
 	int error;
@@ -718,7 +719,7 @@
 	struct uio auio;
 	struct iovec *iov;
 	struct socket *so;
-	cap_rights_t *rights;
+	const cap_rights_t *rights;
 #ifdef KTRACE
 	struct uio *ktruio = NULL;
 #endif
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -4409,7 +4409,7 @@
  * semantics.
  */
 int
-getvnode_path(struct thread *td, int fd, cap_rights_t *rightsp,
+getvnode_path(struct thread *td, int fd, const cap_rights_t *rightsp,
     struct file **fpp)
 {
 	struct file *fp;
@@ -4447,7 +4447,8 @@
  * A reference on the file entry is held upon returning.
  */
 int
-getvnode(struct thread *td, int fd, cap_rights_t *rightsp, struct file **fpp)
+getvnode(struct thread *td, int fd, const cap_rights_t *rightsp,
+    struct file **fpp)
 {
 	int error;
 
diff --git a/sys/sys/file.h b/sys/sys/file.h
--- a/sys/sys/file.h
+++ b/sys/sys/file.h
@@ -258,14 +258,15 @@
 extern int maxfiles;		/* kernel limit on number of open files */
 extern int maxfilesperproc;	/* per process limit on number of open files */
 
-int fget(struct thread *td, int fd, cap_rights_t *rightsp, struct file **fpp);
-int fget_mmap(struct thread *td, int fd, cap_rights_t *rightsp,
+int fget(struct thread *td, int fd, const cap_rights_t *rightsp,
+    struct file **fpp);
+int fget_mmap(struct thread *td, int fd, const cap_rights_t *rightsp,
     vm_prot_t *maxprotp, struct file **fpp);
-int fget_read(struct thread *td, int fd, cap_rights_t *rightsp,
+int fget_read(struct thread *td, int fd, const cap_rights_t *rightsp,
     struct file **fpp);
-int fget_write(struct thread *td, int fd, cap_rights_t *rightsp,
+int fget_write(struct thread *td, int fd, const cap_rights_t *rightsp,
     struct file **fpp);
-int fget_fcntl(struct thread *td, int fd, cap_rights_t *rightsp,
+int fget_fcntl(struct thread *td, int fd, const cap_rights_t *rightsp,
     int needfcntl, struct file **fpp);
 int _fdrop(struct file *fp, struct thread *td);
 int fget_remote(struct thread *td, struct proc *p, int fd, struct file **fpp);
@@ -290,15 +291,15 @@
 
 void finit(struct file *, u_int, short, void *, const struct fileops *);
 void finit_vnode(struct file *, u_int, void *, const struct fileops *);
-int fgetvp(struct thread *td, int fd, cap_rights_t *rightsp,
+int fgetvp(struct thread *td, int fd, const cap_rights_t *rightsp,
     struct vnode **vpp);
-int fgetvp_exec(struct thread *td, int fd, cap_rights_t *rightsp,
+int fgetvp_exec(struct thread *td, int fd, const cap_rights_t *rightsp,
     struct vnode **vpp);
-int fgetvp_rights(struct thread *td, int fd, cap_rights_t *needrightsp,
+int fgetvp_rights(struct thread *td, int fd, const cap_rights_t *needrightsp,
     struct filecaps *havecaps, struct vnode **vpp);
-int fgetvp_read(struct thread *td, int fd, cap_rights_t *rightsp,
+int fgetvp_read(struct thread *td, int fd, const cap_rights_t *rightsp,
     struct vnode **vpp);
-int fgetvp_write(struct thread *td, int fd, cap_rights_t *rightsp,
+int fgetvp_write(struct thread *td, int fd, const cap_rights_t *rightsp,
     struct vnode **vpp);
 int fgetvp_lookup_smr(struct nameidata *ndp, struct vnode **vpp, bool *fsearch);
 int fgetvp_lookup(struct nameidata *ndp, struct vnode **vpp);
diff --git a/sys/sys/filedesc.h b/sys/sys/filedesc.h
--- a/sys/sys/filedesc.h
+++ b/sys/sys/filedesc.h
@@ -275,22 +275,23 @@
 struct filedesc_to_leader *
 	filedesc_to_leader_share(struct filedesc_to_leader *fdtol,
 	    struct filedesc *fdp);
-int	getvnode(struct thread *td, int fd, cap_rights_t *rightsp,
+int	getvnode(struct thread *td, int fd, const cap_rights_t *rightsp,
 	    struct file **fpp);
-int	getvnode_path(struct thread *td, int fd, cap_rights_t *rightsp,
+int	getvnode_path(struct thread *td, int fd, const cap_rights_t *rightsp,
 	    struct file **fpp);
 void	mountcheckdirs(struct vnode *olddp, struct vnode *newdp);
 
-int	fget_cap_noref(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
-	    struct file **fpp, struct filecaps *havecapsp);
-int	fget_cap(struct thread *td, int fd, cap_rights_t *needrightsp,
+int	fget_cap_noref(struct filedesc *fdp, int fd,
+	    const cap_rights_t *needrightsp, struct file **fpp,
+	    struct filecaps *havecapsp);
+int	fget_cap(struct thread *td, int fd, const cap_rights_t *needrightsp,
 	    struct file **fpp, struct filecaps *havecapsp);
 /* Return a referenced file from an unlocked descriptor. */
-int	fget_unlocked(struct thread *td, int fd, cap_rights_t *needrightsp,
-	    struct file **fpp);
+int	fget_unlocked(struct thread *td, int fd,
+	    const cap_rights_t *needrightsp, struct file **fpp);
 /* Return a file pointer without a ref. FILEDESC_IS_ONLY_USER must be true.  */
-int	fget_only_user(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
-	    struct file **fpp);
+int	fget_only_user(struct filedesc *fdp, int fd,
+	    const cap_rights_t *needrightsp, struct file **fpp);
 #define	fput_only_user(fdp, fp)	({					\
 	MPASS(FILEDESC_IS_ONLY_USER(fdp));				\
 	MPASS(refcount_load(&fp->f_count) > 0);				\
diff --git a/sys/sys/namei.h b/sys/sys/namei.h
--- a/sys/sys/namei.h
+++ b/sys/sys/namei.h
@@ -70,7 +70,7 @@
 	 */
 	const	char *ni_dirp;		/* pathname pointer */
 	enum	uio_seg ni_segflg;	/* location of pathname */
-	cap_rights_t *ni_rightsneeded;	/* rights required to look up vnode */
+	const cap_rights_t *ni_rightsneeded; /* rights needed to look up vnode */
 	/*
 	 * Arguments to lookup.
 	 */
@@ -244,7 +244,7 @@
 #define NDINIT_ALL(ndp, op, flags, segflg, namep, dirfd, startdir, rightsp)	\
 do {										\
 	struct nameidata *_ndp = (ndp);						\
-	cap_rights_t *_rightsp = (rightsp);					\
+	const cap_rights_t *_rightsp = (rightsp);					\
 	MPASS(_rightsp != NULL);						\
 	NDINIT_PREFILL(_ndp);							\
 	NDINIT_DBG(_ndp);							\
diff --git a/sys/sys/procdesc.h b/sys/sys/procdesc.h
--- a/sys/sys/procdesc.h
+++ b/sys/sys/procdesc.h
@@ -94,8 +94,10 @@
  * In-kernel interfaces to process descriptors.
  */
 int	 procdesc_exit(struct proc *);
-int	 procdesc_find(struct thread *, int fd, cap_rights_t *, struct proc **);
-int	 kern_pdgetpid(struct thread *, int fd, cap_rights_t *, pid_t *pidp);
+int	 procdesc_find(struct thread *, int fd, const cap_rights_t *,
+	    struct proc **);
+int	 kern_pdgetpid(struct thread *, int fd, const cap_rights_t *,
+	    pid_t *pidp);
 void	 procdesc_new(struct proc *, int);
 void	 procdesc_finit(struct procdesc *, struct file *);
 pid_t	 procdesc_pid(struct file *);
diff --git a/sys/sys/socketvar.h b/sys/sys/socketvar.h
--- a/sys/sys/socketvar.h
+++ b/sys/sys/socketvar.h
@@ -488,9 +488,9 @@
  */
 int	getsockaddr(struct sockaddr **namp, const struct sockaddr *uaddr,
 	    size_t len);
-int	getsock_cap(struct thread *td, int fd, cap_rights_t *rightsp,
+int	getsock_cap(struct thread *td, int fd, const cap_rights_t *rightsp,
 	    struct file **fpp, struct filecaps *havecaps);
-int	getsock(struct thread *td, int fd, cap_rights_t *rightsp,
+int	getsock(struct thread *td, int fd, const cap_rights_t *rightsp,
 	    struct file **fpp);
 void	soabort(struct socket *so);
 int	soaccept(struct socket *so, struct sockaddr *sa);