create_run_template: tell the template what caller's uid was mapped to

src/lxc/conf.c

@@ -2912,7 +2912,7 @@ uid_t get_mapped_rootid(struct lxc_conf *conf)
 	return (uid_t)-1;
 }
 
-bool hostid_is_mapped(int id, struct lxc_conf *conf)
+int mapped_hostid(int id, struct lxc_conf *conf)
 {
 	struct lxc_list *it;
 	struct id_map *map;
@@ -2921,9 +2921,9 @@ bool hostid_is_mapped(int id, struct lxc_conf *conf)
 		if (map->idtype != ID_TYPE_UID)
 			continue;
 		if (id >= map->hostid && id < map->hostid + map->range)
-			return true;
+			return (id - map->hostid) + map->nsid;
 	}
-	return false;
+	return -1;
 }
 
 int find_unmapped_nsuid(struct lxc_conf *conf)

src/lxc/conf.h

@@ -362,7 +362,7 @@ extern void lxc_rename_phys_nics_on_shutdown(struct lxc_conf *conf);
 
 extern uid_t get_mapped_rootid(struct lxc_conf *conf);
 extern int find_unmapped_nsuid(struct lxc_conf *conf);
-extern bool hostid_is_mapped(int id, struct lxc_conf *conf);
+extern int mapped_hostid(int id, struct lxc_conf *conf);
 extern int chown_mapped_root(char *path, struct lxc_conf *conf);
 extern int ttys_shift_ids(struct lxc_conf *c);
 #endif

src/lxc/lxccontainer.c

@@ -917,20 +917,27 @@ static bool create_run_template(struct lxc_container *c, char *tpath, bool quiet
 		 * If we're running the template in a mapped userns, then
 		 * we prepend the template command with:
 		 * lxc-usernsexec <-m map1> ... <-m mapn> --
+		 * and we append "--mapped-uid x", where x is the mapped uid
+		 * for our geteuid()
 		 */
 		if (geteuid() != 0 && !lxc_list_empty(&conf->id_map)) {
 			int n2args = 1;
+			char txtuid[20];
 			char **n2 = malloc(n2args * sizeof(*n2));
 			struct lxc_list *it;
 			struct id_map *map;
 
+			if (!n2) {
+				SYSERROR("out of memory");
+				exit(1);
+			}
 			newargv[0] = tpath;
 			tpath = "lxc-usernsexec";
 			n2[0] = "lxc-usernsexec";
 			lxc_list_for_each(it, &conf->id_map) {
 				map = it->elem;
 				n2args += 2;
-				n2 = realloc(n2, n2args * sizeof(*n2));
+				n2 = realloc(n2, n2args * sizeof(char *));
 				if (!n2)
 					exit(1);
 				n2[n2args-2] = "-m";
@@ -943,15 +950,15 @@ static bool create_run_template(struct lxc_container *c, char *tpath, bool quiet
 				if (ret < 0 || ret >= 200)
 					exit(1);
 			}
-			bool hostid_mapped = hostid_is_mapped(geteuid(), conf);
-			int extraargs = hostid_mapped ?  1 : 3;
-			n2 = realloc(n2, (nargs + n2args + extraargs) * sizeof(*n2));
+			int hostid_mapped = mapped_hostid(geteuid(), conf);
+			int extraargs = hostid_mapped >= 0 ?  1 : 3;
+			n2 = realloc(n2, (nargs + n2args + extraargs) * sizeof(char *));
 			if (!n2)
 				exit(1);
-			if (!hostid_mapped) {
-				int free_id = find_unmapped_nsuid(conf);
+			if (hostid_mapped < 0) {
+				hostid_mapped = find_unmapped_nsuid(conf);
 				n2[n2args++] = "-m";
-				if (free_id < 0) {
+				if (hostid_mapped < 0) {
 					ERROR("Could not find free uid to map");
 					exit(1);
 				}
@@ -961,7 +968,7 @@ static bool create_run_template(struct lxc_container *c, char *tpath, bool quiet
 					exit(1);
 				}
 				ret = snprintf(n2[n2args-1], 200, "u:%d:%d:1",
-					free_id, geteuid());
+					hostid_mapped, geteuid());
 				if (ret < 0 || ret >= 200) {
 					ERROR("string too long");
 					exit(1);
@@ -970,6 +977,20 @@ static bool create_run_template(struct lxc_container *c, char *tpath, bool quiet
 			n2[n2args++] = "--";
 			for (i = 0; i < nargs; i++)
 				n2[i + n2args] = newargv[i];
+			n2args += nargs;
+			// Finally add "--mapped-uid $uid" to tell template what to chown
+			// cached images to
+			n2args += 2;
+			n2 = realloc(n2, n2args * sizeof(char *));
+			if (!n2) {
+				SYSERROR("out of memory");
+				exit(1);
+			}
+			// note n2[n2args-1] is NULL
+			n2[n2args-3] = "--mapped-uid";
+			snprintf(txtuid, 20, "%d", hostid_mapped);
+			n2[n2args-2] = txtuid;
+			n2[n2args-1] = NULL;
 			free(newargv);
 			newargv = n2;
 		}

templates/lxc-ubuntu-cloud.in

@@ -80,7 +80,11 @@ lxc.cap.drop = sys_module mac_admin mac_override sys_time
 #lxc.hook.mount = /usr/share/lxc/hooks/mountcgroups
 
 lxc.hook.clone = ${CLONE_HOOK_FN}
+EOF
 
+    # can't write to devices.deny without CAP_SYS_ADMIN in init-user-ns
+    if [ $in_userns -ne 1 ]; then
+	    cat <<EOF >> $path/config
 lxc.cgroup.devices.deny = a
 # Allow any mknod (but not using the node)
 lxc.cgroup.devices.allow = c *:* m
@@ -109,6 +113,7 @@ lxc.cgroup.devices.allow = c 10:228 rwm
 # kvm
 lxc.cgroup.devices.allow = c 10:232 rwm
 EOF
+    fi
 
     cat <<EOF > $path/fstab
 proc            proc         proc    nodev,noexec,nosuid 0 0
@@ -123,6 +128,7 @@ EOF
     # that in the kernel, but not right now.  So let's just bind
     # mount the files from the host.
     if [ $in_userns -eq 1 ]; then
+        mkdir -p $rootfs/dev/pts
         for dev in null tty urandom console; do
             touch $rootfs/dev/$dev
             echo "/dev/$dev dev/$dev    none bind 0 0" >> $path/fstab
@@ -161,13 +167,14 @@ EOF
     return 0
 }
 
-options=$(getopt -o a:hp:r:n:Fi:CLS:T:ds:u: -l arch:,help,rootfs:,path:,release:,name:,flush-cache,hostid:,auth-key:,cloud,no_locales,tarball:,debug,stream:,userdata: -- "$@")
+options=$(getopt -o a:hp:r:n:Fi:CLS:T:ds:u: -l arch:,help,rootfs:,path:,release:,name:,flush-cache,hostid:,auth-key:,cloud,no_locales,tarball:,debug,stream:,userdata:,mapped-uid: -- "$@")
 if [ $? -ne 0 ]; then
     usage $(basename $0)
     exit 1
 fi
 eval set -- "$options"
 
+mapped_uid=-1
 # default release is precise, or the systems release if recognized
 release=precise
 if [ -f /etc/lsb-release ]; then
@@ -224,11 +231,13 @@ do
     -u|--userdata)     cloneargs[${#cloneargs[@]}]="--userdata=$2"; shift 2;;
     -C|--cloud)        cloneargs[${#cloneargs[@]}]="--cloud"; shift 1;;
     -S|--auth-key)     cloneargs[${#cloneargs[@]}]="--auth-key=$2"; shift 2;;
+    --mapped-uid)      mapped_uid=$2; shift 2;;
     --)                shift 1; break ;;
         *)              break ;;
     esac
 done
 
+echo "mapped_uid is .$mapped_uid."
 cloneargs=( "--name=$name" "${cloneargs[@]}" )
 
 if [ $debug -eq 1 ]; then
@@ -296,6 +305,8 @@ type wget
 # determine the url, tarball, and directory names
 # download if needed
 cache="$STATE_DIR/cache/lxc/cloud-$release"
+STATE_DIR="$HOME/.cache/lxc/"
+cache="$HOME/.cache/lxc/cloud-$release"
 
 mkdir -p $cache
 
@@ -371,7 +382,11 @@ do_extract_rootfs() {
     echo "Extracting container rootfs"
     mkdir -p $rootfs
     cd $rootfs
-    tar --numeric-owner -xpzf "$cache/$filename"
+    if [ $in_userns -eq 1 ]; then
+        tar --anchored --exclude="dev/*" --numeric-owner -xpzf "$cache/$filename"
+    else
+        tar --numeric-owner -xpzf "$cache/$filename"
+    fi
 }
 
 if [ -n "$tarball" ]; then
@@ -388,6 +403,12 @@ copy_configuration $path $rootfs $name $arch $release
 
 "$CLONE_HOOK_FN" "${cloneargs[@]}" "$rootfs"
 
+if [ $mapped_uid -ne -1 ]; then
+	chown $mapped_uid $path/config
+	chown -R $mapped_uid $STATE_DIR
+	chown -R $mapped_uid $cache
+fi
+
 echo "Container $name created."
 exit 0