Quoting Christian Brauner (christianvanbrau...@gmail.com): > When using overlay and aufs mounts with lxc.mount.entry users have to specify > absolute paths for upperdir and workdir which will then get created > automatically by mount_entry_create_overlay_dirs() and > mount_entry_create_aufs_dirs() in conf.c. When we clone a container with > overlay or aufs lxc.mount.entry entries we need to update these absolute > paths. > In order to do this we add the function update_ovl_paths() in > lxccontainer.c. The function updates the mounts in two locations: > > 1) lxc_conf->mount_list > > and > > 2) lxc_conf->unexpanded_config (by calling > clone_update_unexp_ovl_dir()) > > If we were to only update 2) we would end up with wrong upperdir and workdir > mounts as the absolute paths would still point to the container that serves as > the base for the clone. If we were to only update 1) we would end up with > wrong > upperdir and workdir lxc.mount.entry entries in the clone's config as the > absolute paths in upperdir and workdir would still point to the container that > serves as the base for the clone. Updating both will get the job done. > > NOTE: This function does not sanitize paths apart from removing trailing > slashes. (So when a user specifies //home//someone/// it will be cleaned to > //home//someone. This is the minimal path cleansing which is also done by > lxc_container_new().) But the mount_entry_create_overlay_dirs() and > mount_entry_create_aufs_dirs() functions both try to be extremely strict about > when to create upperdirs and workdirs. They will only accept sanitized paths, > i.e. they require /home/someone. I think this is a (safety) virtue and we > should consider sanitizing paths in general. In short: update_ovl_paths() does > update all absolute paths to the new container but > mount_entry_create_overlay_dirs() and mount_entry_create_aufs_dirs() will > still > refuse to create upperdir and workdir when the updated path is unclean. This > happens easily when e.g. a user calls lxc-clone -o OLD -n NEW -P > //home//chb///. > > Signed-off-by: Christian Brauner <christianvanbrau...@gmail.com> > --- > src/lxc/lxccontainer.c | 98 > ++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 98 insertions(+) > > diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c > index 42e23e7..7150103 100644 > --- a/src/lxc/lxccontainer.c > +++ b/src/lxc/lxccontainer.c > @@ -2894,6 +2894,100 @@ static int create_file_dirname(char *path, struct > lxc_conf *conf) > return ret; > } > > +/* When we clone a container with overlay lxc.mount.entry entries we need to > +* update absolute paths for upper- and workdir. This update is done in two > +* locations: lxc_conf->unexpanded_config and lxc_conf->mount_list. Both > updates > +* are done independent of each other since lxc_conf->mountlist may container > +* more mount entries (e.g. from other included files) than > +* lxc_conf->unexpanded_config . */ > +static int update_ovl_paths(struct lxc_conf *lxc_conf, const char *lxc_path, > + const char *lxc_name, const char *newpath, > + const char *newname) > +{ > + char new_upper[MAXPATHLEN]; > + char new_work[MAXPATHLEN]; > + char old_upper[MAXPATHLEN]; > + char old_work[MAXPATHLEN]; > + char *cleanpath = NULL; > + int i; > + int fret = -1; > + int ret = 0; > + struct lxc_list *iterator; > + const char *ovl_dirs[] = {"br", "upperdir", "workdir"}; > + > + cleanpath = strdup(newpath); > + if (!cleanpath) > + goto err; > + > + remove_trailing_slashes(cleanpath); > + > + /* We have to update lxc_conf->unexpanded_config separately from > + * lxc_conf->mount_list. */ > + for (i = 0; i < sizeof(ovl_dirs) / sizeof(ovl_dirs[0]); i++) { > + if (!clone_update_unexp_ovl_paths(lxc_conf, lxc_path, newpath, > + lxc_name, newname, > + ovl_dirs[i])) > + goto err; > + } > + > + ret = snprintf(old_work, MAXPATHLEN, "workdir=%s/%s", lxc_path, > lxc_name); > + if (ret < 0 || ret >= MAXPATHLEN) > + goto err; > + > + ret = snprintf(new_work, MAXPATHLEN, "workdir=%s/%s", cleanpath, > newname); > + if (ret < 0 || ret >= MAXPATHLEN) > + goto err; > + > + lxc_list_for_each(iterator, &lxc_conf->mount_list) { > + char *mnt_entry = NULL; > + char *new_mnt_entry = NULL; > + char *tmp = NULL; > + char *tmp_mnt_entry = NULL; > + mnt_entry = iterator->elem; > + > + if (strstr(mnt_entry, "overlay")) > + tmp = "upperdir"; > + else if (strstr(mnt_entry, "aufs")) > + tmp = "br"; > + > + if (!tmp) > + continue; > +
The rest of this block needs to be un-indented by one level. > + ret = snprintf(old_upper, MAXPATHLEN, "%s=%s/%s", tmp, > lxc_path, lxc_name); > + if (ret < 0 || ret >= MAXPATHLEN) > + goto err; > + > + ret = snprintf(new_upper, MAXPATHLEN, "%s=%s/%s", tmp, > cleanpath, newname); > + if (ret < 0 || ret >= MAXPATHLEN) > + goto err; > + > + if (strstr(mnt_entry, old_upper)) { > + tmp_mnt_entry = lxc_string_replace(old_upper, > new_upper, mnt_entry); > + } > + > + if (strstr(mnt_entry, old_work)) { > + if (tmp_mnt_entry) > + new_mnt_entry = > lxc_string_replace(old_work, new_work, tmp_mnt_entry); Don't you want old_work replaced even if old_upper wasn't found? (or are we requiring limitations on the old upper that guarantee that won't happen?) > + > + if (new_mnt_entry) { > + free(iterator->elem); > + iterator->elem = strdup(new_mnt_entry); > + } else if (tmp_mnt_entry) { > + free(iterator->elem); > + iterator->elem = strdup(tmp_mnt_entry); > + } > + > + free(new_mnt_entry); > + free(tmp_mnt_entry); > + } > + > + fret = 0; > +err: > + free(cleanpath); > + return fret; > +} > + > static struct lxc_container *do_lxcapi_clone(struct lxc_container *c, const > char *newname, > const char *lxcpath, int flags, > const char *bdevtype, const char *bdevdata, uint64_t newsize, > @@ -3009,6 +3103,10 @@ static struct lxc_container *do_lxcapi_clone(struct > lxc_container *c, const char > } > } > > + // update absolute paths for overlay mount directories > + if (update_ovl_paths(c2->lxc_conf, c->config_path, c->name, lxcpath, > newname) < 0) > + goto out; > + > // We've now successfully created c2's storage, so clear it out if we > // fail after this > storage_copied = 1; > -- > 2.6.2 > _______________________________________________ lxc-devel mailing list lxc-devel@lists.linuxcontainers.org http://lists.linuxcontainers.org/listinfo/lxc-devel