[lxc-devel] [PATCH] handle unprivileged user calls more gracefully (v2)
Stéphane Graber
stgraber at ubuntu.com
Sat Jan 18 04:49:03 UTC 2014
On Fri, Jan 17, 2014 at 11:34:50PM -0500, S.Çağlar Onur wrote:
> Return an error if the function is not supposed to be called by an unprivileged user.
> Otherwise those calls fail in the middle of their execution with different reasons.
>
> changes since v1:
> - am_unpriv is now a simple geteuid check,
> - API functions are now providing error messages,
> - lxc-info, lxc-attach and lxc-execute are now checking geteuid
>
That looks much better to me, though I disagree that lxc-execute doesn't
work. It certainly is a bit restricted compared ot its system
equivalent, but all of those limitations will be the same as with
lxc-start.
stgraber at castiana:~$ lxc-execute -n p1 -- /bin/bash
lxc-init: failed to mount /proc : Device or resource busy
lxc-init: failed to mount /dev/shm : No such file or directory
root at p1:/#
It may be worth teaching lxc_init a bit about unprivileged containers
but besides that, if all I wanted to do was run a command using that
container rootfs, it'd work.
The rest I think looks good and hopefully we can drop quite a few of
those before the 1.0 release. It shouldn't be too hard to get basic dir
cloning working and a good chunk of the rest would get resolved if we
had attach working.
Ideally, we'd release with only the snapshot functions and the
add/remove device function disabled as those simply aren't doable at
this point.
> Signed-off-by: S.Çağlar Onur <caglar at 10ur.org>
> ---
> src/lxc/lxc_attach.c | 5 ++++
> src/lxc/lxc_execute.c | 5 ++++
> src/lxc/lxc_info.c | 20 +++++++------
> src/lxc/lxccontainer.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++----
> 4 files changed, 95 insertions(+), 13 deletions(-)
>
> diff --git a/src/lxc/lxc_attach.c b/src/lxc/lxc_attach.c
> index 6744c05..1159d09 100644
> --- a/src/lxc/lxc_attach.c
> +++ b/src/lxc/lxc_attach.c
> @@ -188,6 +188,11 @@ int main(int argc, char *argv[])
> lxc_attach_options_t attach_options = LXC_ATTACH_OPTIONS_DEFAULT;
> lxc_attach_command_t command;
>
> + if (geteuid() != 0) {
> + ERROR("lxc-attach is not currently supported with unprivileged containers");
> + return -1;
> + }
> +
> ret = lxc_caps_init();
> if (ret)
> return ret;
> diff --git a/src/lxc/lxc_execute.c b/src/lxc/lxc_execute.c
> index 6a54bf6..8177ed3 100644
> --- a/src/lxc/lxc_execute.c
> +++ b/src/lxc/lxc_execute.c
> @@ -92,6 +92,11 @@ int main(int argc, char *argv[])
> char *rcfile;
> struct lxc_conf *conf;
>
> + if (geteuid() != 0) {
> + ERROR("lxc-execute is not currently supported with unprivileged containers");
> + return -1;
> + }
> +
> lxc_list_init(&defines);
>
> if (lxc_caps_init())
> diff --git a/src/lxc/lxc_info.c b/src/lxc/lxc_info.c
> index b515087..0990036 100644
> --- a/src/lxc/lxc_info.c
> +++ b/src/lxc/lxc_info.c
> @@ -310,15 +310,19 @@ static int print_info(const char *name, const char *lxcpath)
> }
>
> if (ips) {
> - char **addresses = c->get_ips(c, NULL, NULL, 0);
> - if (addresses) {
> - char *address;
> - i = 0;
> - while (addresses[i]) {
> - address = addresses[i];
> - print_info_msg_str("IP:", address);
> - i++;
> + if (geteuid() == 0) {
> + char **addresses = c->get_ips(c, NULL, NULL, 0);
> + if (addresses) {
> + char *address;
> + i = 0;
> + while (addresses[i]) {
> + address = addresses[i];
> + print_info_msg_str("IP:", address);
> + i++;
> + }
> }
> + } else {
> + print_info_msg_str("IP:", "UNKNOWN");
> }
> }
>
> diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> index 0bebdff..368cb46 100644
> --- a/src/lxc/lxccontainer.c
> +++ b/src/lxc/lxccontainer.c
> @@ -62,8 +62,14 @@
>
> #define MAX_BUFFER 4096
>
> +#define NOT_SUPPORTED_ERROR "the requested function %s is not currently supported with unprivileged containers"
> +
> lxc_log_define(lxc_container, lxc);
>
> +inline static bool am_unpriv() {
> + return geteuid() != 0;
> +}
> +
> static bool file_exists(const char *f)
> {
> struct stat statbuf;
> @@ -1489,6 +1495,11 @@ static char** lxcapi_get_interfaces(struct lxc_container *c)
> char **interfaces = NULL;
> int old_netns = -1, new_netns = -1;
>
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + goto out;
> + }
> +
> if (!enter_to_ns(c, &old_netns, &new_netns))
> goto out;
>
> @@ -1538,6 +1549,11 @@ static char** lxcapi_get_ips(struct lxc_container *c, const char* interface, con
> char *address = NULL;
> int old_netns = -1, new_netns = -1;
>
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + goto out;
> + }
> +
> if (!enter_to_ns(c, &old_netns, &new_netns))
> goto out;
>
> @@ -1818,7 +1834,7 @@ static int lxc_rmdir_onedev_wrapper(void *data)
> static bool lxcapi_destroy(struct lxc_container *c)
> {
> struct bdev *r = NULL;
> - bool bret = false, am_unpriv;
> + bool bret = false;
> int ret;
>
> if (!c || !lxcapi_is_defined(c))
> @@ -1833,14 +1849,12 @@ static bool lxcapi_destroy(struct lxc_container *c)
> goto out;
> }
>
> - am_unpriv = c->lxc_conf && geteuid() != 0 && !lxc_list_empty(&c->lxc_conf->id_map);
> -
> if (c->lxc_conf && has_snapshots(c)) {
> ERROR("container %s has dependent snapshots", c->name);
> goto out;
> }
>
> - if (!am_unpriv && c->lxc_conf->rootfs.path && c->lxc_conf->rootfs.mount) {
> + if (!am_unpriv() && c->lxc_conf->rootfs.path && c->lxc_conf->rootfs.mount) {
> r = bdev_init(c->lxc_conf->rootfs.path, c->lxc_conf->rootfs.mount, NULL);
> if (r) {
> if (r->ops->destroy(r) < 0) {
> @@ -1857,7 +1871,7 @@ static bool lxcapi_destroy(struct lxc_container *c)
> const char *p1 = lxcapi_get_config_path(c);
> char *path = alloca(strlen(p1) + strlen(c->name) + 2);
> sprintf(path, "%s/%s", p1, c->name);
> - if (am_unpriv)
> + if (am_unpriv())
> ret = userns_exec_1(c->lxc_conf, lxc_rmdir_onedev_wrapper, path);
> else
> ret = lxc_rmdir_onedev(path);
> @@ -2406,6 +2420,11 @@ static struct lxc_container *lxcapi_clone(struct lxc_container *c, const char *n
> if (!c || !c->is_defined(c))
> return NULL;
>
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return NULL;
> + }
> +
> if (container_mem_lock(c))
> return NULL;
>
> @@ -2515,6 +2534,11 @@ static bool lxcapi_rename(struct lxc_container *c, const char *newname)
> if (!c || !c->name || !c->config_path)
> return false;
>
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return false;
> + }
> +
> bdev = bdev_init(c->lxc_conf->rootfs.path, c->lxc_conf->rootfs.mount, NULL);
> if (!bdev) {
> ERROR("Failed to find original backing store type");
> @@ -2543,6 +2567,11 @@ static int lxcapi_attach(struct lxc_container *c, lxc_attach_exec_t exec_functio
> if (!c)
> return -1;
>
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return -1;
> + }
> +
> return lxc_attach(c->name, c->config_path, exec_function, exec_payload, options, attached_process);
> }
>
> @@ -2555,6 +2584,11 @@ static int lxcapi_attach_run_wait(struct lxc_container *c, lxc_attach_options_t
> if (!c)
> return -1;
>
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return -1;
> + }
> +
> command.program = (char*)program;
> command.argv = (char**)argv;
> r = lxc_attach(c->name, c->config_path, lxc_attach_run_command, &command, options, &pid);
> @@ -2587,6 +2621,11 @@ static int lxcapi_snapshot(struct lxc_container *c, const char *commentfile)
> struct lxc_container *c2;
> char snappath[MAXPATHLEN], newname[20];
>
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return -1;
> + }
> +
> // /var/lib/lxc -> /var/lib/lxcsnaps \0
> ret = snprintf(snappath, MAXPATHLEN, "%ssnaps/%s", c->config_path, c->name);
> if (ret < 0 || ret >= MAXPATHLEN)
> @@ -2724,6 +2763,12 @@ static int lxcapi_snapshot_list(struct lxc_container *c, struct lxc_snapshot **r
>
> if (!c || !lxcapi_is_defined(c))
> return -1;
> +
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return -1;
> + }
> +
> // snappath is ${lxcpath}snaps/${lxcname}/
> dirlen = snprintf(snappath, MAXPATHLEN, "%ssnaps/%s", c->config_path, c->name);
> if (dirlen < 0 || dirlen >= MAXPATHLEN) {
> @@ -2802,6 +2847,11 @@ static bool lxcapi_snapshot_restore(struct lxc_container *c, const char *snapnam
> if (!c || !c->name || !c->config_path)
> return false;
>
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return false;
> + }
> +
> bdev = bdev_init(c->lxc_conf->rootfs.path, c->lxc_conf->rootfs.mount, NULL);
> if (!bdev) {
> ERROR("Failed to find original backing store type");
> @@ -2851,6 +2901,11 @@ static bool lxcapi_snapshot_destroy(struct lxc_container *c, const char *snapnam
> if (!c || !c->name || !c->config_path)
> return false;
>
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return false;
> + }
> +
> ret = snprintf(clonelxcpath, MAXPATHLEN, "%ssnaps/%s", c->config_path, c->name);
> if (ret < 0 || ret >= MAXPATHLEN)
> goto err;
> @@ -2967,11 +3022,19 @@ out:
>
> static bool lxcapi_add_device_node(struct lxc_container *c, const char *src_path, const char *dest_path)
> {
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return false;
> + }
> return add_remove_device_node(c, src_path, dest_path, true);
> }
>
> static bool lxcapi_remove_device_node(struct lxc_container *c, const char *src_path, const char *dest_path)
> {
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return false;
> + }
> return add_remove_device_node(c, src_path, dest_path, false);
> }
>
> @@ -2984,6 +3047,11 @@ static int lxcapi_attach_run_waitl(struct lxc_container *c, lxc_attach_options_t
> if (!c)
> return -1;
>
> + if (am_unpriv()) {
> + ERROR(NOT_SUPPORTED_ERROR, __FUNCTION__);
> + return -1;
> + }
> +
> va_start(ap, arg);
> argv = lxc_va_arg_list_to_argv_const(ap, 1);
> va_end(ap);
> --
> 1.8.3.2
>
> _______________________________________________
> lxc-devel mailing list
> lxc-devel at lists.linuxcontainers.org
> http://lists.linuxcontainers.org/listinfo/lxc-devel
--
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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