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Rework /dev, /sys, /proc mounting

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- assume all entries in @devfiles to be in /dev
 - allow for /dev, /sys and /proc not to exist in the target and print warning
 - allow for /dev entries as well as /sys and /proc not to exist on the outside
 - simplify umount by storing special options in @umountopts
 - remove superfluous checks for root and unshare mode
 - make sure /dev entries are less than 100 chars in size for tar
This commit is contained in:
Johannes Schauer Marin Rodrigues 2021-03-08 08:04:35 +01:00
parent d52eaa4814
commit 5a3d1ab5c4
Signed by untrusted user: josch
GPG key ID: F2CBA5C78FBD83E1
2 changed files with 201 additions and 102 deletions
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47
coverage.sh
View file

@ -120,7 +120,7 @@ if [ ! -e shared/hooks/eatmydata/customize.sh ] || [ hooks/eatmydata/customize.s
fi
fi
starttime=
total=191
total=193
skipped=0
runtests=0
i=1
@ -937,6 +937,51 @@ else
runtests=$((runtests+1))
fi
print_header "mode=unshare,variant=apt: missing device nodes outside the chroot"
cat << END > shared/test.sh
#!/bin/sh
set -eu
export LC_ALL=C.UTF-8
if [ ! -e /mmdebstrap-testenv ]; then
echo "this test modifies the system and should only be run inside a container" >&2
exit 1
fi
rm /dev/console
adduser --gecos user --disabled-password user
sysctl -w kernel.unprivileged_userns_clone=1
runuser -u user -- $CMD --mode=unshare --variant=apt $DEFAULT_DIST /tmp/debian-chroot.tar $mirror
tar -tf /tmp/debian-chroot.tar | sort | diff -u tar1.txt -
rm /tmp/debian-chroot.tar
END
if [ "$HAVE_QEMU" = "yes" ]; then
./run_qemu.sh
runtests=$((runtests+1))
else
echo "HAVE_QEMU != yes -- Skipping test..." >&2
skipped=$((skipped+1))
fi
print_header "mode=unshare,variant=custom: missing /dev, /sys, /proc inside the chroot"
cat << END > shared/test.sh
#!/bin/sh
set -eu
export LC_ALL=C.UTF-8
if [ ! -e /mmdebstrap-testenv ]; then
echo "this test modifies the system and should only be run inside a container" >&2
exit 1
fi
adduser --gecos user --disabled-password user
sysctl -w kernel.unprivileged_userns_clone=1
runuser -u user -- $CMD --mode=unshare --variant=custom --include=dpkg,dash,diffutils,coreutils,libc-bin,sed $DEFAULT_DIST /dev/null $mirror
END
if [ "$HAVE_QEMU" = "yes" ]; then
./run_qemu.sh
runtests=$((runtests+1))
else
echo "HAVE_QEMU != yes -- Skipping test..." >&2
skipped=$((skipped+1))
fi
print_header "mode=root,variant=apt: chroot directory not accessible by _apt user"
cat << END > shared/test.sh
#!/bin/sh

256
mmdebstrap
View file

@ -61,6 +61,7 @@ our ($CLONE_NEWNS, $CLONE_NEWUTS, $CLONE_NEWIPC,
$CLONE_NEWUSER, $CLONE_NEWPID, $CLONE_NEWNET,
$_LINUX_CAPABILITY_VERSION_3, $CAP_SYS_ADMIN);
#<<<
# type codes:
# 0 -> normal file
# 1 -> hardlink
@ -69,23 +70,24 @@ our ($CLONE_NEWNS, $CLONE_NEWUTS, $CLONE_NEWIPC,
# 4 -> block special
# 5 -> directory
my @devfiles = (
# filename mode type link target major minor
["./dev/", oct(755), 5, '', undef, undef],
["./dev/console", oct(666), 3, '', 5, 1],
["./dev/fd", oct(777), 2, '/proc/self/fd', undef, undef],
["./dev/full", oct(666), 3, '', 1, 7],
["./dev/null", oct(666), 3, '', 1, 3],
["./dev/ptmx", oct(666), 3, '', 5, 2],
["./dev/pts/", oct(755), 5, '', undef, undef],
["./dev/random", oct(666), 3, '', 1, 8],
["./dev/shm/", oct(755), 5, '', undef, undef],
["./dev/stderr", oct(777), 2, '/proc/self/fd/2', undef, undef],
["./dev/stdin", oct(777), 2, '/proc/self/fd/0', undef, undef],
["./dev/stdout", oct(777), 2, '/proc/self/fd/1', undef, undef],
["./dev/tty", oct(666), 3, '', 5, 0],
["./dev/urandom", oct(666), 3, '', 1, 9],
["./dev/zero", oct(666), 3, '', 1, 5],
# filename mode type link target major minor
["", oct(755), 5, '', undef, undef],
["console", oct(666), 3, '', 5, 1],
["fd", oct(777), 2, '/proc/self/fd', undef, undef],
["full", oct(666), 3, '', 1, 7],
["null", oct(666), 3, '', 1, 3],
["ptmx", oct(666), 3, '', 5, 2],
["pts/", oct(755), 5, '', undef, undef],
["random", oct(666), 3, '', 1, 8],
["shm/", oct(755), 5, '', undef, undef],
["stderr", oct(777), 2, '/proc/self/fd/2', undef, undef],
["stdin", oct(777), 2, '/proc/self/fd/0', undef, undef],
["stdout", oct(777), 2, '/proc/self/fd/1', undef, undef],
["tty", oct(666), 3, '', 5, 0],
["urandom", oct(666), 3, '', 1, 9],
["zero", oct(666), 3, '', 1, 5],
);
#>>>
# verbosity levels:
# 0 -> print nothing
@ -918,84 +920,111 @@ sub run_chroot {
foreach my $file (@devfiles) {
my ($fname, $mode, $type, $linkname, $devmajor, $devminor)
= @{$file};
next if $fname eq './dev/';
next if $fname eq '';
if ($type == 0) { # normal file
error "type 0 not implemented";
} elsif ($type == 1) { # hardlink
error "type 1 not implemented";
} elsif ($type == 2) { # symlink
if (!$options->{havemknod}) {
if ( $options->{mode} eq 'fakechroot'
and $linkname =~ /^\/proc/) {
# there is no /proc in fakechroot mode
# If we had mknod, then the symlink was already created
# in the run_setup function.
if (!-d "$options->{root}/dev") {
warning(
"skipping creation of ./dev/$fname because the"
. " /dev directory is missing in the target"
);
next;
}
if (
any { $_ eq $options->{mode} }
('root', 'unshare')
) {
push @cleanup_tasks, sub {
unlink "$options->{root}/$fname"
or warn "cannot unlink $fname: $!";
}
}
symlink $linkname, "$options->{root}/$fname"
or error "cannot create symlink $fname";
push @cleanup_tasks, sub {
unlink "$options->{root}/dev/$fname"
or warn "cannot unlink ./dev/$fname: $!";
};
symlink $linkname, "$options->{root}/dev/$fname"
or error
"cannot create symlink ./dev/$fname -> $linkname";
}
} elsif ($type == 3 or $type == 4) {
# character/block special
if ($options->{mode} eq 'root' && !$options->{canmount}) {
warning "skipping bind-mounting $fname";
warning "skipping bind-mounting ./dev/$fname";
} elsif (!$options->{havemknod}) {
open my $fh, '>', "$options->{root}/$fname"
or error "cannot open $options->{root}/$fname: $!";
close $fh;
if ($options->{mode} eq 'unshare') {
push @cleanup_tasks, sub {
0 == system('umount', '--no-mtab',
"$options->{root}/$fname")
or warn "umount $fname failed: $?";
unlink "$options->{root}/$fname"
or warn "cannot unlink $fname: $!";
};
} elsif ($options->{mode} eq 'root') {
push @cleanup_tasks, sub {
0 == system('umount',
"$options->{root}/$fname")
or warn "umount failed: $?";
unlink "$options->{root}/$fname"
or warn "cannot unlink $fname: $!";
};
} else {
error "unknown mode: $options->{mode}";
if (!-d "$options->{root}/dev") {
warning(
"skipping creation of ./dev/$fname because the"
. " /dev directory is missing in the target"
);
next;
}
0 == system('mount', '-o', 'bind', "/$fname",
"$options->{root}/$fname")
or error "mount $fname failed: $?";
if (!-e "/dev/$fname") {
warning("skipping creation of ./dev/$fname because"
. " /dev/$fname does not exist"
. " on the outside");
next;
}
if (!-c "/dev/$fname") {
warning("skipping creation of ./dev/$fname because"
. " /dev/$fname on the outside is not a"
. " character special file");
next;
}
open my $fh, '>', "$options->{root}/dev/$fname"
or error
"cannot open $options->{root}/dev/$fname: $!";
close $fh;
my @umountopts = ();
if ($options->{mode} eq 'unshare') {
push @umountopts, '--no-mtab';
}
push @cleanup_tasks, sub {
0 == system('umount', @umountopts,
"$options->{root}/dev/$fname")
or warn "umount ./dev/$fname failed: $?";
unlink "$options->{root}/dev/$fname"
or warn "cannot unlink ./dev/$fname: $!";
};
0 == system('mount', '-o', 'bind', "/dev/$fname",
"$options->{root}/dev/$fname")
or error "mount ./dev/$fname failed: $?";
}
} elsif ($type == 5
&& $options->{mode} eq 'root'
&& !$options->{canmount}) {
warning "skipping bind-mounting $fname";
warning "skipping bind-mounting ./dev/$fname";
} elsif ($type == 5) { # directory
if (!-d "$options->{root}/dev") {
warning(
"skipping creation of ./dev/$fname because the"
. " /dev directory is missing in the target");
next;
}
if (!-e "/dev/$fname") {
warning("skipping creation of ./dev/$fname because"
. " /dev/$fname does not exist"
. " on the outside");
next;
}
if (!-d "/dev/$fname") {
warning("skipping creation of ./dev/$fname because"
. " /dev/$fname on the outside is not a"
. " directory");
next;
}
if (!$options->{havemknod}) {
if (
any { $_ eq $options->{mode} }
('root', 'unshare')
) {
push @cleanup_tasks, sub {
rmdir "$options->{root}/$fname"
or warn "cannot rmdir $fname: $!";
}
}
if (-e "$options->{root}/$fname") {
if (!-d "$options->{root}/$fname") {
error "$fname already exists but is not a"
. " directory";
# If had mknod, then the directory to bind-mount into
# was already created in the run_setup function.
push @cleanup_tasks, sub {
rmdir "$options->{root}/dev/$fname"
or warn "cannot rmdir ./dev/$fname: $!";
};
if (-e "$options->{root}/dev/$fname") {
if (!-d "$options->{root}/dev/$fname") {
error "./dev/$fname already exists but is not"
. " a directory";
}
} else {
my $num_created
= make_path "$options->{root}/$fname",
= make_path "$options->{root}/dev/$fname",
{ error => \my $err };
if ($err && @$err) {
error(
@ -1007,29 +1036,25 @@ sub run_chroot {
} @$err
));
} elsif ($num_created == 0) {
error "cannot create $options->{root}/$fname";
error
"cannot create $options->{root}/dev/$fname";
}
}
chmod $mode, "$options->{root}/$fname"
or error "cannot chmod $fname: $!";
chmod $mode, "$options->{root}/dev/$fname"
or error "cannot chmod ./dev/$fname: $!";
}
my @umountopts = ();
if ($options->{mode} eq 'unshare') {
push @cleanup_tasks, sub {
0 == system('umount', '--no-mtab',
"$options->{root}/$fname")
or warn "umount $fname failed: $?";
};
} elsif ($options->{mode} eq 'root') {
push @cleanup_tasks, sub {
0 == system('umount', "$options->{root}/$fname")
or warn "umount $fname failed: $?";
};
} else {
error "unknown mode: $options->{mode}";
push @umountopts, '--no-mtab';
}
0 == system('mount', '-o', 'bind', "/$fname",
"$options->{root}/$fname")
or error "mount $fname failed: $?";
push @cleanup_tasks, sub {
0 == system('umount', @umountopts,
"$options->{root}/dev/$fname")
or warn "umount ./dev/$fname failed: $?";
};
0 == system('mount', '-o', 'bind', "/dev/$fname",
"$options->{root}/dev/$fname")
or error "mount ./dev/$fname failed: $?";
} else {
error "unsupported type: $type";
}
@ -1049,6 +1074,9 @@ sub run_chroot {
# to extract those
if ($options->{mode} eq 'root' && !$options->{canmount}) {
warning "skipping mount sysfs";
} elsif ($options->{mode} eq 'root' && !-d "$options->{root}/sys") {
warning("skipping mounting of sysfs because the"
. " /sys directory is missing in the target");
} elsif ($options->{mode} eq 'root') {
push @cleanup_tasks, sub {
0 == system('umount', "$options->{root}/sys")
@ -1059,6 +1087,15 @@ sub run_chroot {
'-o', 'ro,nosuid,nodev,noexec', 'sys',
"$options->{root}/sys"
) or error "mount /sys failed: $?";
} elsif ($options->{mode} eq 'unshare' && !-d "$options->{root}/sys") {
warning("skipping bind-mounting /sys because the"
. " /sys directory is missing in the target");
} elsif ($options->{mode} eq 'unshare' && !-e "/sys") {
warning("skipping bind-mounting /sys because"
. " /sys does not exist on the outside");
} elsif ($options->{mode} eq 'unshare' && !-d "/sys") {
warning("skipping bind-mounting /sys because"
. " /sys on the outside is not a directory");
} elsif ($options->{mode} eq 'unshare') {
# naturally we have to clean up after ourselves in sudo mode where
# we do a real mount. But we also need to unmount in unshare mode
@ -1091,6 +1128,9 @@ sub run_chroot {
}
if ($options->{mode} eq 'root' && !$options->{canmount}) {
warning "skipping mount proc";
} elsif ($options->{mode} eq 'root' && !-d "$options->{root}/proc") {
warning("skipping mounting of proc because the"
. " /proc directory is missing in the target");
} elsif ($options->{mode} eq 'root') {
push @cleanup_tasks, sub {
# some maintainer scripts mount additional stuff into /proc
@ -1110,6 +1150,16 @@ sub run_chroot {
0 == system('mount', '-t', 'proc', '-o', 'ro', 'proc',
"$options->{root}/proc")
or error "mount /proc failed: $?";
} elsif ($options->{mode} eq 'unshare' && !-d "$options->{root}/proc")
{
warning("skipping bind-mounting /proc because the"
. " /proc directory is missing in the target");
} elsif ($options->{mode} eq 'unshare' && !-e "/proc") {
warning("skipping bind-mounting /proc because"
. " /proc does not exist on the outside");
} elsif ($options->{mode} eq 'unshare' && !-d "/proc") {
warning("skipping bind-mounting /proc because"
. " /proc on the outside is not a directory");
} elsif ($options->{mode} eq 'unshare') {
# naturally we have to clean up after ourselves in sudo mode where
# we do a real mount. But we also need to unmount in unshare mode
@ -1781,24 +1831,25 @@ sub run_setup() {
# there is no /proc in fakechroot mode
next;
}
symlink $linkname, "$options->{root}/$fname"
or error "cannot create symlink $fname";
symlink $linkname, "$options->{root}/dev/$fname"
or error "cannot create symlink ./dev/$fname";
next; # chmod cannot work on symlinks
} elsif ($type == 3) { # character special
0 == system('mknod', "$options->{root}/$fname", 'c',
0 == system('mknod', "$options->{root}/dev/$fname", 'c',
$devmajor, $devminor)
or error "mknod failed: $?";
} elsif ($type == 4) { # block special
0 == system('mknod', "$options->{root}/$fname", 'b',
0 == system('mknod', "$options->{root}/dev/$fname", 'b',
$devmajor, $devminor)
or error "mknod failed: $?";
} elsif ($type == 5) { # directory
if (-e "$options->{root}/$fname") {
if (!-d "$options->{root}/$fname") {
error "$fname already exists but is not a directory";
if (-e "$options->{root}/dev/$fname") {
if (!-d "$options->{root}/dev/$fname") {
error
"./dev/$fname already exists but is not a directory";
}
} else {
my $num_created = make_path "$options->{root}/$fname",
my $num_created = make_path "$options->{root}/dev/$fname",
{ error => \my $err };
if ($err && @$err) {
error(
@ -1808,14 +1859,14 @@ sub run_setup() {
@$err
));
} elsif ($num_created == 0) {
error "cannot create $options->{root}/$fname";
error "cannot create $options->{root}/dev/$fname";
}
}
} else {
error "unsupported type: $type";
}
chmod $mode, "$options->{root}/$fname"
or error "cannot chmod $fname: $!";
chmod $mode, "$options->{root}/dev/$fname"
or error "cannot chmod ./dev/$fname: $!";
}
}
@ -5314,9 +5365,12 @@ sub main() {
foreach my $file (@devfiles) {
my ($fname, $mode, $type, $linkname, $devmajor, $devminor)
= @{$file};
if (length "./dev/$fname" > 100) {
error "tar entry cannot exceed 100 characters";
}
my $entry = pack(
'a100 a8 a8 a8 a12 a12 A8 a1 a100 a8 a32 a32 a8 a8 a155 x12',
$fname,
"./dev/$fname",
sprintf('%07o', $mode),
sprintf('%07o', 0), # uid
sprintf('%07o', 0), # gid