vmtest: update root fs, whitelist sk_{assign|lookup} test

1. Update mkrootfs.sh building root fs
- Remove /etc/fstab from root fs and mount each fs type separately in
S10-mount script.
- devtmpfs can be already mounted prior to S10-mount execution so make
it opt-out. This addresses [0].
- set -eux for scripts
2. Add iproute2 to root fs and whitelist sk_assign test. Addresses
[1][2]. Update INDEX file with 2020-09-27 version.

[0] https://github.com/libbpf/libbpf/pull/145#issuecomment-609673493
[1] https://github.com/libbpf/libbpf/pull/144
[2] https://github.com/libbpf/libbpf/pull/145

travis-ci/vmtest/configs/INDEX

@@ -1,5 +1,5 @@
 INDEX	https://libbpf-vmtest.s3-us-west-1.amazonaws.com/x86_64/INDEX
-libbpf-vmtest-rootfs-2020.03.11.tar.zst	https://libbpf-vmtest.s3-us-west-1.amazonaws.com/x86_64/libbpf-vmtest-rootfs-2020.03.11.tar.zst
+libbpf-vmtest-rootfs-2020.09.27.tar.zst	https://libbpf-vmtest.s3-us-west-1.amazonaws.com/x86_64/libbpf-vmtest-rootfs-2020.09.27.tar.zst
 vmlinux-4.9.0.zst	https://libbpf-vmtest.s3-us-west-1.amazonaws.com/x86_64/vmlinux-4.9.0.zst
 vmlinux-5.5.0-rc6.zst	https://libbpf-vmtest.s3-us-west-1.amazonaws.com/x86_64/vmlinux-5.5.0-rc6.zst
 vmlinux-5.5.0.zst	https://libbpf-vmtest.s3-us-west-1.amazonaws.com/x86_64/vmlinux-5.5.0.zst

travis-ci/vmtest/configs/blacklist/BLACKLIST-latest

@@ -1,7 +1,5 @@
 # TEMPORARILY DISABLED
 send_signal		# flaky
 test_lsm		# semi-working
-sk_assign		# needs better setup in Travis CI
-sk_lookup
 core_reloc		# temporary test breakage
 bpf_verif_scale		# clang regression

travis-ci/vmtest/mkrootfs.sh

@@ -81,6 +81,7 @@ packages=(
 	binutils
 	elfutils
 	glibc
+	iproute2
 	# selftests test_verifier dependencies.
 	libcap
 )
@@ -101,15 +102,6 @@ rm -rf "$root/usr/share/{doc,help,man,texinfo}"
 
 chroot "${root}" /bin/busybox --install
 
-cat > "$root/etc/fstab" << "EOF"
-dev /dev devtmpfs rw,nosuid 0 0
-proc /proc proc rw,nosuid,nodev,noexec 0 0
-sys /sys sysfs rw,nosuid,nodev,noexec 0 0
-debugfs /sys/kernel/debug debugfs mode=755,realtime 0 0
-bpffs /sys/fs/bpf bpf realtime 0 0
-EOF
-chmod 644 "$root/etc/fstab"
-
 cat > "$root/etc/inittab" << "EOF"
 ::sysinit:/etc/init.d/rcS
 ::ctrlaltdel:/sbin/reboot
@@ -123,13 +115,29 @@ mkdir -m 755 "$root/etc/init.d" "$root/etc/rcS.d"
 cat > "$root/etc/rcS.d/S10-mount" << "EOF"
 #!/bin/sh
 
-/bin/mount -a
+set -eux
+
+/bin/mount proc /proc -t proc
+
+# Mount devtmpfs if not mounted
+if [[ -z $(/bin/mount -l -t devtmpfs) ]]; then
+	/bin/mount devtmpfs /dev -t devtmpfs
+fi
+
+/bin/mount sysfs /sys -t sysfs
+/bin/mount bpffs /sys/fs/bpf -t bpf
+/bin/mount debugfs /sys/kernel/debug -t debugfs
+
+echo 'Listing currently mounted file systems'
+/bin/mount
 EOF
 chmod 755 "$root/etc/rcS.d/S10-mount"
 
 cat > "$root/etc/rcS.d/S40-network" << "EOF"
 #!/bin/sh
 
+set -eux
+
 ip link set lo up
 EOF
 chmod 755 "$root/etc/rcS.d/S40-network"
@@ -137,6 +145,8 @@ chmod 755 "$root/etc/rcS.d/S40-network"
 cat > "$root/etc/init.d/rcS" << "EOF"
 #!/bin/sh
 
+set -eux
+
 for path in /etc/rcS.d/S*; do
 	[ -x "$path" ] && "$path"
 done

travis-ci/vmtest/run.sh

@@ -411,7 +411,7 @@ if [[ ! -z SETUPCMD ]]; then
 	if [[ -v BUILDDIR ]]; then kernel='latest'; fi
 	setup_envvars="export KERNEL=${kernel}"
 	setup_script=$(printf "#!/bin/sh
-set -e
+set -eux
 
 echo 'Running setup commands'
 %s