Re: [libvirt] [PATCH 2/2] Ensure root filesystem is recursively mounted readonly

From: "Daniel P. Berrange" <berrange(a)redhat.com&gt; If the guest is configured with <filesystem type='mount'> <source dir='/'/> <target dir='/'/> <readonly/> </filesystem> Then any submounts under / should also end up readonly, except for those setup as basic mounts. eg if the user has /home on a separate volume, they'd expect /home to be readonly, but we should not touch the /sys, /proc, etc dirs we setup ourselves. Users can selectively make sub-mounts read-write again by simply listing them as new mounts without the <readonly> flag set <filesystem type='mount'> <source dir='/home'/> <target dir='/home'/> </filesystem> Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com&gt; --- src/lxc/lxc_container.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 88 insertions(+), 2 deletions(-) diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c index d51cdc4..38d95b0 100644 --- a/src/lxc/lxc_container.c +++ b/src/lxc/lxc_container.c @@ -532,7 +532,6 @@ static int lxcContainerGetSubtree(const char *prefix, } while (getmntent_r(procmnt, &mntent, mntbuf, sizeof(mntbuf)) != NULL) { - VIR_DEBUG("Got %s", mntent.mnt_dir); if (!STRPREFIX(mntent.mnt_dir, prefix)) continue; @@ -541,7 +540,6 @@ static int lxcContainerGetSubtree(const char *prefix, if (VIR_STRDUP(mounts[nmounts], mntent.mnt_dir) < 0) goto cleanup; nmounts++; - VIR_DEBUG("Grabbed %s", mntent.mnt_dir); } if (mounts) @@ -779,6 +777,76 @@ static const virLXCBasicMountInfo lxcBasicMounts[] = { }; +static bool lxcIsBasicMountLocation(const char *path) +{ + size_t i; + + for (i = 0; i < ARRAY_CARDINALITY(lxcBasicMounts); i++) { + if (STRPREFIX(path, lxcBasicMounts[i].dst)) + return true;

+ + while (getmntent_r(procmnt, &mntent, mntbuf, sizeof(mntbuf)) != NULL) { + if (STREQ(mntent.mnt_dir, "/") || + STREQ(mntent.mnt_dir, "/.oldroot") || + STRPREFIX(mntent.mnt_dir, "/.oldroot/") || + lxcIsBasicMountLocation(mntent.mnt_dir)) + continue;