Quoting Christian Brauner ([email protected]): > On Tue, Oct 20, 2015 at 04:17:18PM +0000, Serge Hallyn wrote: > > Quoting Christian Brauner ([email protected]): > > > 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_union_mount_entry_paths() > > > in > > > lxccontainer.c. The function updates the mounts in two locations: > > > > > > 1) lxc_conf->mount_list > > > > > > and > > > > > > 2) lxc_conf->unexpanded_config > > > > > > 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, > > > that an entry in lxc_conf->mount_list will only be updated if it is also > > > found > > > in the clones config. Mounts from other files are hence not updated. In > > > short, > > > automatic overlay and aufs mounts with lxc.mount.entry should only be > > > specified > > > in the containers own config. > > > > > > 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_union_mount_entry_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 <[email protected]> > > > --- > > > src/lxc/lxccontainer.c | 133 > > > ++++++++++++++++++++++++++++++++++++++++++++++++- > > > 1 file changed, 132 insertions(+), 1 deletion(-) > > > > > > diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c > > > index 42e23e7..5ed7697 100644 > > > --- a/src/lxc/lxccontainer.c > > > +++ b/src/lxc/lxccontainer.c > > > @@ -2894,6 +2894,130 @@ static int create_file_dirname(char *path, struct > > > lxc_conf *conf) > > > return ret; > > > } > > > > > > +/* 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_union_mount_entry_paths() in lxccontainer.c. The function > > > operates on > > > +* c->lxc_conf->unexpanded_config instead of the intuitively plausible > > > +* c->lxc_conf->mount_list because the latter also contains mounts from > > > other > > > +* files as well as generic mounts. */ > > > +static int update_union_mount_entry_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; > > > + char *mnt_entry = NULL; > > > + char *new_mnt_entry = NULL; > > > + char *new_unexpanded_config = NULL; > > > + char *tmp_mnt_entry = NULL; > > > + char *tmp_unexpanded_config = NULL; > > > + char *tmp = NULL; > > > + int ret = 0; > > > + size_t len = 0; > > > + struct lxc_list *iterator; > > > + > > > + cleanpath = strdup(newpath); > > > + if (!cleanpath) > > > + goto err; > > > + > > > + remove_trailing_slashes(cleanpath); > > > + > > > + 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) { > > > > put > > > > char *tmp = NULL, new_mnt_entry = NULL; > > char *mnt_entry; > > > > here (and remove from above etc). > > > > > + mnt_entry = iterator->elem; > > > + > > > + if (strstr(mnt_entry, "overlay")) > > > + tmp = "upperdir"; > > > + else if (strstr(mnt_entry, "aufs")) > > > + tmp = "br"; > > > + > > > + if (!tmp) > > > + continue; > > > + > > > + if (strstr(lxc_conf->unexpanded_config, mnt_entry)) { > > > + ret = snprintf(old_upper, MAXPATHLEN, "%s=%s/%s", tmp, > > > lxc_path, lxc_name); > > > + if (ret < 0 || ret >= MAXPATHLEN) > > > + goto err; > > > > Alternate suggestion. How about using clear_unexp_config_line() to remove > > all > > lxc.mount.entry lines from unexpanded config first, then run through this > > loop > > and simply add the new ones? > > > > The lxc_string_replace approach feels problematic. > > I thought so too, but clear_unexp_config_line() will not just clear mount > entries from the containers config but also entries from files like > common.conf > which are also present in lxc_conf->mount_list e.g.:
Hm, might be the other way around, but yeah we can't do that. But if the config file has say a commented version of the line before the real line, you'll update only the comment right? So can you do lik eclear_unexp_config_line() does and make sure you are looking for only lines beginning with "lxc.mount.entry += +" and then have the mnt_entry? I guess that should do. The need for unexpanded config is very unfortunate. _______________________________________________ lxc-devel mailing list [email protected] http://lists.linuxcontainers.org/listinfo/lxc-devel
