posixshm: Add a -j option to posixshmcontrol ls, to specify a jail

PR:		257556
Reported by:	grembo@

usr.bin/posixshmcontrol/Makefile

@@ -1,6 +1,6 @@
 # $FreeBSD$
 
 PROG=   posixshmcontrol
-LIBADD=	util
+LIBADD=	jail util
 
 .include <bsd.prog.mk>

usr.bin/posixshmcontrol/posixshmcontrol.1

@@ -27,7 +27,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd March 18, 2020
+.Dd February 26, 2022
 .Dt POSIXSHMCONTROL 1
 .Os
 .Sh NAME
@@ -45,6 +45,7 @@
 .Ar ls
 .Op Fl h
 .Op Fl n
+.Op Fl j Ar jail
 .Nm
 .Ar dump
 .Op Pa path \&...
@@ -87,6 +88,11 @@ Unlink the paths specified.
 .It Ic ls
 List all linked named shared memory segments visible to the caller.
 For each segment, the user and group owner, size, and path are displayed.
+The
+.Fl j
+option limits the output to segments within the specified
+.Ar jail
+name or id.
 .It Ic dump
 Output raw bytes values from the segment to standard output.
 .It Ic stat

usr.bin/posixshmcontrol/posixshmcontrol.c

@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
 #include <err.h>
 #include <fcntl.h>
 #include <grp.h>
+#include <jail.h>
 #include <libutil.h>
 #include <pwd.h>
 #include <stdbool.h>
@@ -54,7 +55,7 @@ usage(void)
 	fprintf(stderr, "Usage:\n"
 	    "posixshmcontrol create [-m <mode>] [-l <largepage>] <path> ...\n"
 	    "posixshmcontrol rm <path> ...\n"
-	    "posixshmcontrol ls [-h] [-n]\n"
+	    "posixshmcontrol ls [-h] [-n] [-j jail]\n"
 	    "posixshmcontrol dump <path> ...\n"
 	    "posixshmcontrol stat [-h] [-n] <path> ...\n"
 	    "posixshmcontrol truncate [-s <newlen>] <path> ...\n");
@@ -221,17 +222,19 @@ shm_decode_mode(mode_t m, char *str)
 static int
 list_shm(int argc, char **argv)
 {
-	char *buf, *bp, sizebuf[8], str[10];
+	char *buf, *bp, *ep, jailpath[MAXPATHLEN], sizebuf[8], str[10];
+	const char *jailparam;
 	const struct kinfo_file *kif;
 	struct stat st;
-	int c, error, fd, mib[3], ret;
-	size_t len, miblen;
-	bool hsize, uname;
+	int c, error, fd, jid, mib[3], ret;
+	size_t len, jailpathlen, miblen;
+	bool hsize, jailed, uname;
 
 	hsize = false;
+	jailed = false;
 	uname = true;
 
-	while ((c = getopt(argc, argv, "hn")) != -1) {
+	while ((c = getopt(argc, argv, "hj:n")) != -1) {
 		switch (c) {
 		case 'h':
 			hsize = true;
@@ -239,6 +242,28 @@ list_shm(int argc, char **argv)
 		case 'n':
 			uname = false;
 			break;
+		case 'j':
+			jid = strtoul(optarg, &ep, 10);
+			if (ep > optarg && !*ep) {
+				jailparam = "jid";
+				jailed = jid > 0;
+			} else {
+				jailparam = "name";
+				jailed = true;
+			}
+			if (jailed) {
+				if (jail_getv(0, jailparam, optarg, "path",
+				    jailpath, NULL) < 0) {
+					if (errno == ENOENT)
+						warnx("no such jail: %s", optarg);
+					else
+						warnx("%s", jail_errmsg);
+					return (1);
+				}
+				jailpathlen = strlen(jailpath);
+				jailpath[jailpathlen] = '/';
+			}
+			break;
 		default:
 			usage();
 			return (2);
@@ -279,6 +304,8 @@ list_shm(int argc, char **argv)
 		kif = (const struct kinfo_file *)(void *)bp;
 		if (kif->kf_structsize == 0)
 			break;
+		if (jailed && strncmp(kif->kf_path, jailpath, jailpathlen + 1))
+			continue;
 		fd = shm_open(kif->kf_path, O_RDONLY, 0);
 		if (fd == -1) {
 			warn("open %s", kif->kf_path);