| Message ID | 20191017133155.5327-2-mreitz@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iotests: Add and use $SOCK_DIR | expand |
On 10/17/19 8:31 AM, Max Reitz wrote: > Unix sockets generally have a maximum path length. Depending on your > $TEST_DIR, it may be exceeded and then all tests that create and use > Unix sockets there may fail. > > Circumvent this by adding a new scratch directory specifically for > Unix socket files. It defaults to a temporary directory (mktemp -d) > that is completely removed after the iotests are done. > > (By default, mktemp -d creates a /tmp/tmp.XXXXXXXXXX directory, which > should be short enough for our use cases.) > > Use mkdir -p to create the directory (because it seems right), and do > the same for $TEST_DIR (because there is no reason for that to be > created in any different way). > > Signed-off-by: Max Reitz <mreitz@redhat.com> > --- > tests/qemu-iotests/check | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > @@ -116,10 +117,14 @@ set_prog_path() > if [ -z "$TEST_DIR" ]; then > TEST_DIR=$PWD/scratch > fi > +mkdir -p "$TEST_DIR" || _init_error 'Failed to create TEST_DIR' This one seems fine. We are either using the user's name (and if it is pre-existing, not fail) or using a well-known name (if someone else slams in files into that directory in parallel with our test run, oh well). But at least the well-known name is a directory that is probably already accessible only to the current user, not world-writable. > > -if [ ! -e "$TEST_DIR" ]; then > - mkdir "$TEST_DIR" > +tmp_sock_dir=false > +if [ -z "$SOCK_DIR" ]; then > + SOCK_DIR=$(mktemp -d) > + tmp_sock_dir=true > fi > +mkdir -p "$SOCK_DIR" || _init_error 'Failed to create SOCK_DIR' Thinking about this again: if the user passed in a name, we probably want to use it no matter whether the directory already exists (mkdir -p makes sense: either the directory did not exist, or the user is in charge of passing us a directory that they already secured). But if we generate our own name in a world-writable location in /tmp, using mkdir -p means someone else can race us to the creation of the directory, and potentially populate it in a way to cause us a security hole while we execute our tests. I would be a bit more comfortable with: tmp_sock_dir=false tmp_sock_opt=-p if [ -z "$SOCK_DIR" ]; then SOCK_DIR=$(mktemp -d) tmp_sock_dir=true tmp_sock_opt= # disable -p for our generated name fi mkdir $tmp_sock_opt "$SOCK_DIR" || _init_error 'Failed to create SOCK_DIR'
On 17.10.19 16:52, Eric Blake wrote: > On 10/17/19 8:31 AM, Max Reitz wrote: >> Unix sockets generally have a maximum path length. Depending on your >> $TEST_DIR, it may be exceeded and then all tests that create and use >> Unix sockets there may fail. >> >> Circumvent this by adding a new scratch directory specifically for >> Unix socket files. It defaults to a temporary directory (mktemp -d) >> that is completely removed after the iotests are done. >> >> (By default, mktemp -d creates a /tmp/tmp.XXXXXXXXXX directory, which >> should be short enough for our use cases.) >> >> Use mkdir -p to create the directory (because it seems right), and do >> the same for $TEST_DIR (because there is no reason for that to be >> created in any different way). >> >> Signed-off-by: Max Reitz <mreitz@redhat.com> >> --- >> tests/qemu-iotests/check | 15 +++++++++++++-- >> 1 file changed, 13 insertions(+), 2 deletions(-) > >> @@ -116,10 +117,14 @@ set_prog_path() >> if [ -z "$TEST_DIR" ]; then >> TEST_DIR=$PWD/scratch >> fi >> +mkdir -p "$TEST_DIR" || _init_error 'Failed to create TEST_DIR' > > This one seems fine. We are either using the user's name (and if it is > pre-existing, not fail) or using a well-known name (if someone else > slams in files into that directory in parallel with our test run, oh > well). But at least the well-known name is a directory that is probably > already accessible only to the current user, not world-writable. > >> -if [ ! -e "$TEST_DIR" ]; then >> - mkdir "$TEST_DIR" >> +tmp_sock_dir=false >> +if [ -z "$SOCK_DIR" ]; then >> + SOCK_DIR=$(mktemp -d) >> + tmp_sock_dir=true >> fi >> +mkdir -p "$SOCK_DIR" || _init_error 'Failed to create SOCK_DIR' > > Thinking about this again: if the user passed in a name, we probably > want to use it no matter whether the directory already exists (mkdir -p > makes sense: either the directory did not exist, or the user is in > charge of passing us a directory that they already secured). But if we > generate our own name in a world-writable location in /tmp, using mkdir > -p means someone else can race us to the creation of the directory, and > potentially populate it in a way to cause us a security hole while we > execute our tests. I don’t quite see how this is a security hole. mktemp -d creates the directory, so noone can race us. Max > I would be a bit more comfortable with: > > tmp_sock_dir=false > tmp_sock_opt=-p > if [ -z "$SOCK_DIR" ]; then > SOCK_DIR=$(mktemp -d) > tmp_sock_dir=true > tmp_sock_opt= # disable -p for our generated name > fi > mkdir $tmp_sock_opt "$SOCK_DIR" || _init_error 'Failed to create SOCK_DIR' >
On 10/18/19 4:03 AM, Max Reitz wrote: >>> -if [ ! -e "$TEST_DIR" ]; then >>> - mkdir "$TEST_DIR" >>> +tmp_sock_dir=false >>> +if [ -z "$SOCK_DIR" ]; then >>> + SOCK_DIR=$(mktemp -d) >>> + tmp_sock_dir=true >>> fi >>> +mkdir -p "$SOCK_DIR" || _init_error 'Failed to create SOCK_DIR' >> >> Thinking about this again: if the user passed in a name, we probably >> want to use it no matter whether the directory already exists (mkdir -p >> makes sense: either the directory did not exist, or the user is in >> charge of passing us a directory that they already secured). But if we >> generate our own name in a world-writable location in /tmp, using mkdir >> -p means someone else can race us to the creation of the directory, and >> potentially populate it in a way to cause us a security hole while we >> execute our tests. > > I don’t quite see how this is a security hole. mktemp -d creates the > directory, so noone can race us. Aha - I confused 'mktemp -u' (necessary for creating a socket name) and 'mktemp -d' (for directories). With that confusion cleared up, yes, the directory is safely created (or else the burden is on the caller), so: Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/tests/qemu-iotests/check b/tests/qemu-iotests/check index 588c453a94..71fe38834e 100755 --- a/tests/qemu-iotests/check +++ b/tests/qemu-iotests/check @@ -97,6 +97,7 @@ IMGFMT -- $FULL_IMGFMT_DETAILS IMGPROTO -- $IMGPROTO PLATFORM -- $FULL_HOST_DETAILS TEST_DIR -- $TEST_DIR +SOCK_DIR -- $SOCK_DIR SOCKET_SCM_HELPER -- $SOCKET_SCM_HELPER EOF @@ -116,10 +117,14 @@ set_prog_path() if [ -z "$TEST_DIR" ]; then TEST_DIR=$PWD/scratch fi +mkdir -p "$TEST_DIR" || _init_error 'Failed to create TEST_DIR' -if [ ! -e "$TEST_DIR" ]; then - mkdir "$TEST_DIR" +tmp_sock_dir=false +if [ -z "$SOCK_DIR" ]; then + SOCK_DIR=$(mktemp -d) + tmp_sock_dir=true fi +mkdir -p "$SOCK_DIR" || _init_error 'Failed to create SOCK_DIR' diff="diff -u" verbose=false @@ -534,6 +539,7 @@ if [ -z "$SAMPLE_IMG_DIR" ]; then fi export TEST_DIR +export SOCK_DIR export SAMPLE_IMG_DIR if [ -s $tmp.list ] @@ -716,6 +722,11 @@ END { if (NR > 0) { rm -f "${TEST_DIR}"/*.out "${TEST_DIR}"/*.err "${TEST_DIR}"/*.time rm -f "${TEST_DIR}"/check.pid "${TEST_DIR}"/check.sts rm -f $tmp.* + + if $tmp_sock_dir + then + rm -rf "$SOCK_DIR" + fi } trap "_wrapup; exit \$status" 0 1 2 3 15
Unix sockets generally have a maximum path length. Depending on your $TEST_DIR, it may be exceeded and then all tests that create and use Unix sockets there may fail. Circumvent this by adding a new scratch directory specifically for Unix socket files. It defaults to a temporary directory (mktemp -d) that is completely removed after the iotests are done. (By default, mktemp -d creates a /tmp/tmp.XXXXXXXXXX directory, which should be short enough for our use cases.) Use mkdir -p to create the directory (because it seems right), and do the same for $TEST_DIR (because there is no reason for that to be created in any different way). Signed-off-by: Max Reitz <mreitz@redhat.com> --- tests/qemu-iotests/check | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)