[lxc-devel] [PATCH] handle unprivileged user calls more gracefully (v2)
Stéphane Graber
stgraber at ubuntu.com
Sat Jan 18 05:00:37 UTC 2014
On Fri, Jan 17, 2014 at 11:58:17PM -0500, S.Çağlar Onur wrote:
> On Fri, Jan 17, 2014 at 11:49 PM, Stéphane Graber <stgraber at ubuntu.com> wrote:
> > 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:/#
>
> Hmm then I must be having some kind of trouble here with it. I can
> start/stop containers just fine
>
> [caglar at oOo:~/go/src/github.com/caglar10ur/lxc/examples] lxc-start -d -n rubik
> [caglar at oOo:~/go/src/github.com/caglar10ur/lxc/examples] lxc-ls --fancy
> NAME STATE IPV4 IPV6 AUTOSTART
> -------------------------------------------
> rubik RUNNING UNKNOWN UNKNOWN NO
> [caglar at oOo:~/go/src/github.com/caglar10ur/lxc/examples] lxc-stop -n rubik
>
> sudo variant works just fine
>
> [caglar at oOo:~/go/src/github.com/caglar10ur/lxc/examples] sudo
> lxc-execute -n p1 -- /bin/bash
> root at oOo:/home/caglar/go/src/github.com/caglar10ur/lxc/examples# exit
> [caglar at oOo:~/go/src/github.com/caglar10ur/lxc/examples]
>
> but plain one gives this
>
> [caglar at oOo:~/go/src/github.com/caglar10ur/lxc/examples] lxc-execute
> -n p1 -- /bin/bash
> lxc-execute: Operation not permitted - failed to clone
>
> lxc-execute: failed to clone(0x6c020000): Operation not permitted
> lxc-execute: Operation not permitted - failed to fork into a new namespace
> lxc-execute: failed to spawn 'p1'
Try rubik instead of 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
> >
> > _______________________________________________
> > lxc-devel mailing list
> > lxc-devel at lists.linuxcontainers.org
> > http://lists.linuxcontainers.org/listinfo/lxc-devel
> >
>
>
>
> --
> S.Çağlar Onur <caglar at 10ur.org>
> _______________________________________________
> 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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