[lxc-devel] [PATCH] Parse rootfs->path
Christian Brauner
christianvanbrauner at gmail.com
Mon Oct 19 15:31:17 UTC 2015
On Mon, Oct 19, 2015 at 02:50:11PM +0000, Serge Hallyn wrote:
> Quoting Christian Brauner (christianvanbrauner at gmail.com):
> > The mount_entry_overlay_dirs() and mount_entry_aufs_dirs() functions create
> > workdirs and upperdirs for overlay and aufs lxc.mount.entry entries. They try
> > to make sure that the workdirs and upperdirs can only be created under the
> > containerdir (e.g. /path/to/the/container/CONTAINERNAME). In order to do this
> > the right hand side of
> >
> > if ((strncmp(upperdir, lxcpath, dirlen) == 0) && (strncmp(upperdir, rootfs->path, rootfslen) != 0))
> >
> > was thought to check if the rootfs->path is not present in the workdir and
> > upperdir mount options. But the current check is bogus since it will be
> > trivially true whenever the container is a block-dev or overlay or aufs backed
> > since the rootfs->path will then have a form like e.g.
> >
> > overlayfs:/some/path:/some/other/path
> >
> > This patch parses rootfs->path by searching backwards for the first occurrence
> > of the delimiter pair ":/". We do not simply search for ":" since it might be
> > used in path names.
> >
> > Signed-off-by: Christian Brauner <christianvanbrauner at gmail.com>
> > ---
> > src/lxc/conf.c | 126 ++++++++++++++++++++++++++++++++++++++++++++++-----------
> > 1 file changed, 103 insertions(+), 23 deletions(-)
> >
> > diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> > index 16a62f8..a730a67 100644
> > --- a/src/lxc/conf.c
> > +++ b/src/lxc/conf.c
> > @@ -1821,6 +1821,11 @@ static int mount_entry_create_overlay_dirs(const struct mntent *mntent,
> > const char *lxc_path)
> > {
> > char lxcpath[MAXPATHLEN];
> > + char *end = NULL;
> > + char *rootfsdir = NULL;
> > + char *s = NULL;
> > + char *s1 = NULL;
> > + char *tmp = NULL;
> > char *upperdir = NULL;
> > char *workdir = NULL;
> > char **opts = NULL;
> > @@ -1830,15 +1835,16 @@ static int mount_entry_create_overlay_dirs(const struct mntent *mntent,
> > size_t i;
> > size_t len = 0;
> > size_t rootfslen = 0;
> > + size_t slen = 0;
> >
> > if (!rootfs->path || !lxc_name || !lxc_path)
> > - return -1;
> > + goto err;
> >
> > opts = lxc_string_split(mntent->mnt_opts, ',');
> > if (opts)
> > arrlen = lxc_array_len((void **)opts);
> > else
> > - return -1;
> > + goto err;
> >
> > for (i = 0; i < arrlen; i++) {
> > if (strstr(opts[i], "upperdir=") && (strlen(opts[i]) > (len = strlen("upperdir="))))
> > @@ -1848,31 +1854,66 @@ static int mount_entry_create_overlay_dirs(const struct mntent *mntent,
> > }
> >
> > ret = snprintf(lxcpath, MAXPATHLEN, "%s/%s", lxc_path, lxc_name);
> > - if (ret < 0 || ret >= MAXPATHLEN) {
> > - lxc_free_array((void **)opts, free);
> > - return -1;
> > - }
> > + if (ret < 0 || ret >= MAXPATHLEN)
> > + goto err;
> >
> > dirlen = strlen(lxcpath);
> > - rootfslen = strlen(rootfs->path);
> > +
>
> Could you put this stuff into a helper, i.e.
Can do. Do you mean putting it as a static helper function in conf.c, or in
utils.c?
>
> rootfsdir = ovl_get_rootfs_dir(rootfs->path, &rootfslen);
> > + s = strdup(rootfs->path);
> > + if (!s)
> > + goto err;
> > +
> > + s1 = malloc(strlen(rootfs->path) + 1);
> > + if (!s1)
> > + goto err;
> > + end = stpcpy(s1, rootfs->path);
> > +
> > + /* If we find :/ in rootfs->path it means we either have a block-dev or
> > + * overlay or aufs container. */
> > + while ((tmp = strrchr(s, ':'))) {
> > + len = strlen(tmp);
> > + rootfslen += len;
> > + if (strncmp(tmp, ":/", 2) == 0) {
> > + rootfsdir = end - rootfslen + 1;
> > + rootfslen = strlen(rootfsdir);
> > + break;
> > + } else {
> > + slen = strlen(s);
> > + s[slen - len] = '\0';
> > + }
> > + }
> > +
> > + /* If rootfsdir is empty at this point we have a simple directory
> > + * container. */
> > + if (!rootfsdir) {
> > + rootfsdir = rootfs->path;
> > + rootfslen = strlen(rootfs->path);
> > + }
> >
> > /* We neither allow users to create upperdirs and workdirs outside the
> > * containerdir nor inside the rootfs. The latter might be debatable. */
> > if (upperdir)
> > - if ((strncmp(upperdir, lxcpath, dirlen) == 0) && (strncmp(upperdir, rootfs->path, rootfslen) != 0))
> > + if ((strncmp(upperdir, lxcpath, dirlen) == 0) && (strncmp(upperdir, rootfsdir, rootfslen) != 0))
> > if (mkdir_p(upperdir, 0755) < 0) {
> > WARN("Failed to create upperdir");
> > }
> >
> >
> > if (workdir)
> > - if ((strncmp(workdir, lxcpath, dirlen) == 0) && (strncmp(workdir, rootfs->path, rootfslen) != 0))
> > + if ((strncmp(workdir, lxcpath, dirlen) == 0) && (strncmp(workdir, rootfsdir, rootfslen) != 0))
> > if (mkdir_p(workdir, 0755) < 0) {
> > WARN("Failed to create workdir");
> > }
> >
> > + free(s);
> > + free(s1);
> > lxc_free_array((void **)opts, free);
> > return 0;
> > +err:
> > + free(s);
> > + free(s1);
> > + lxc_free_array((void **)opts, free);
> > + return -1;
> > }
> >
> > static int mount_entry_create_aufs_dirs(const struct mntent *mntent,
> > @@ -1881,6 +1922,10 @@ static int mount_entry_create_aufs_dirs(const struct mntent *mntent,
> > const char *lxc_path)
> > {
> > char lxcpath[MAXPATHLEN];
> > + char *end = NULL;
> > + char *rootfsdir = NULL;
> > + char *s = NULL;
> > + char *s1 = NULL;
> > char *scratch = NULL;
> > char *tmp = NULL;
> > char *upperdir = NULL;
> > @@ -1889,44 +1934,79 @@ static int mount_entry_create_aufs_dirs(const struct mntent *mntent,
> > size_t arrlen = 0;
> > size_t i;
> > size_t len = 0;
> > + size_t rootfslen = 0;
> > + size_t slen = 0;
> >
> > if (!rootfs->path || !lxc_name || !lxc_path)
> > - return -1;
> > + goto err;
> >
> > opts = lxc_string_split(mntent->mnt_opts, ',');
> > if (opts)
> > arrlen = lxc_array_len((void **)opts);
> > else
> > - return -1;
> > + goto err;
> >
> > for (i = 0; i < arrlen; i++) {
> > if (strstr(opts[i], "br=") && (strlen(opts[i]) > (len = strlen("br="))))
> > tmp = opts[i] + len;
> > }
> > - if (!tmp) {
> > - lxc_free_array((void **)opts, free);
> > - return -1;
> > - }
> > + if (!tmp)
> > + goto err;
> >
> > upperdir = strtok_r(tmp, ":=", &scratch);
> > - if (!upperdir) {
> > - lxc_free_array((void **)opts, free);
> > - return -1;
> > - }
> > + if (!upperdir)
> > + goto err;
> >
> > ret = snprintf(lxcpath, MAXPATHLEN, "%s/%s", lxc_path, lxc_name);
> > - if (ret < 0 || ret >= MAXPATHLEN) {
> > - lxc_free_array((void **)opts, free);
> > - return -1;
> > + if (ret < 0 || ret >= MAXPATHLEN)
> > + goto err;
> > +
> > + s = strdup(rootfs->path);
> > + if (!s)
> > + goto err;
> > +
> > + s1 = malloc(strlen(rootfs->path) + 1);
> > + if (!s1)
> > + goto err;
> > + end = stpcpy(s1, rootfs->path);
> > +
> > + /* If we find :/ in rootfs->path it means we either have a block-dev or
> > + * overlay or aufs container. */
> > + while ((tmp = strrchr(s, ':'))) {
> > + len = strlen(tmp);
> > + rootfslen += len;
> > + if (strncmp(tmp, ":/", 2) == 0) {
> > + rootfsdir = end - rootfslen + 1;
> > + rootfslen = strlen(rootfsdir);
> > + break;
> > + } else {
> > + slen = strlen(s);
> > + s[slen - len] = '\0';
> > + }
> > + }
> > +
> > + /* If rootfsdir is empty at this point we have a simple directory
> > + * container. */
> > + if (!rootfsdir) {
> > + rootfsdir = rootfs->path;
> > + rootfslen = strlen(rootfs->path);
> > }
> >
> > /* We neither allow users to create upperdirs outside the containerdir
> > * nor inside the rootfs. The latter might be debatable. */
> > - if ((strncmp(upperdir, lxcpath, strlen(lxcpath)) == 0) && (strncmp(upperdir, rootfs->path, strlen(rootfs->path)) != 0))
> > + if ((strncmp(upperdir, lxcpath, strlen(lxcpath)) == 0) && (strncmp(upperdir, rootfsdir, rootfslen) != 0))
> > if (mkdir_p(upperdir, 0755) < 0) {
> > WARN("Failed to create upperdir");
> > }
> >
> > + free(s);
> > + free(s1);
> > + lxc_free_array((void **)opts, free);
> > + return 0;
> > +
> > +err:
> > + free(s);
> > + free(s1);
> > lxc_free_array((void **)opts, free);
> > return 0;
> > }
> > --
> > 2.6.1
> >
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