diff --git a/lib/libc/sys/fcntl.2 b/lib/libc/sys/fcntl.2
--- a/lib/libc/sys/fcntl.2
+++ b/lib/libc/sys/fcntl.2
@@ -28,7 +28,7 @@
 .\"     @(#)fcntl.2	8.2 (Berkeley) 1/12/94
 .\" $FreeBSD$
 .\"
-.Dd January 6, 2021
+.Dd December 7, 2021
 .Dt FCNTL 2
 .Os
 .Sh NAME
@@ -53,7 +53,7 @@
 .Fa cmd ,
 .Fn fcntl
 can take an additional third argument
-.Fa "int arg" .
+.Fa "long arg" .
 .Bl -tag -width F_DUP2FD_CLOEXEC
 .It Dv F_DUPFD
 Return a new descriptor as follows:
@@ -190,6 +190,19 @@
 .Xr mount 2
 or unionfs).
 This is a hack not intended to be used outside of libc.
+.It Dv F_KINFO
+Fills a
+.Vt struct kinfo_file
+for the file referenced by the specified file descriptor.
+The
+.Fa arg
+argument should point to the storage for
+.Vt struct kinfo_file .
+The
+.Va kf_structsize
+member of the passed structure must be initialized with the sizeof of
+.Vt struct kinfo_file ,
+to allow for the interface versioning and evolution.
 .El
 .Pp
 The flags for the
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
@@ -107,6 +107,9 @@
 
 static int	closefp(struct filedesc *fdp, int fd, struct file *fp,
 		    struct thread *td, bool holdleaders, bool audit);
+static void	export_file_to_kinfo(struct file *fp, int fd,
+		    cap_rights_t *rightsp, struct kinfo_file *kif,
+		    struct filedesc *fdp, int flags);
 static int	fd_first_free(struct filedesc *fdp, int low, int size);
 static void	fdgrowtable(struct filedesc *fdp, int nfd);
 static void	fdgrowtable_exp(struct filedesc *fdp, int nfd);
@@ -477,7 +480,8 @@
 	struct proc *p;
 	struct vnode *vp;
 	struct mount *mp;
-	int error, flg, seals, tmp;
+	struct kinfo_file *kif;
+	int error, flg, kif_sz, seals, tmp;
 	uint64_t bsize;
 	off_t foffset;
 
@@ -852,6 +856,41 @@
 		fdrop(fp, td);
 		break;
 
+	case F_KINFO:
+#ifdef CAPABILITY_MODE
+		if (IN_CAPABILITY_MODE(td)) {
+			error = ECAPMODE;
+			break;
+		}
+#endif
+		error = copyin((void *)arg, &kif_sz, sizeof(kif_sz));
+		if (error != 0)
+			break;
+		if (kif_sz != sizeof(*kif)) {
+			error = EINVAL;
+			break;
+		}
+		kif = malloc(sizeof(*kif), M_TEMP, M_WAITOK | M_ZERO);
+		FILEDESC_SLOCK(fdp);
+		error = fget_cap_locked(fdp, fd, &cap_fcntl_rights, &fp, NULL);
+		if (error == 0 && fhold(fp)) {
+			export_file_to_kinfo(fp, fd, NULL, kif, fdp, 0);
+			FILEDESC_SUNLOCK(fdp);
+			fdrop(fp, td);
+			if ((kif->kf_status & KF_ATTR_VALID) != 0) {
+				kif->kf_structsize = sizeof(*kif);
+				error = copyout(kif, (void *)arg, sizeof(*kif));
+			} else {
+				error = EBADF;
+			}
+		} else {
+			FILEDESC_SUNLOCK(fdp);
+			if (error == 0)
+				error = EBADF;
+		}
+		free(kif, M_TEMP);
+		break;
+
 	default:
 		error = EINVAL;
 		break;
diff --git a/sys/sys/fcntl.h b/sys/sys/fcntl.h
--- a/sys/sys/fcntl.h
+++ b/sys/sys/fcntl.h
@@ -270,6 +270,7 @@
 #define	F_ADD_SEALS	19
 #define	F_GET_SEALS	20
 #define	F_ISUNIONSTACK	21		/* Kludge for libc, don't use it. */
+#define	F_KINFO		22		/* Return kinfo_file for this fd */
 
 /* Seals (F_ADD_SEALS, F_GET_SEALS). */
 #define	F_SEAL_SEAL	0x0001		/* Prevent adding sealings */