Re: [libvirt] [RFC PATCH 2/6] LXC: introduce virLXCControllerSetupUserns and lxcContainerSetUserns

This patch introduces new helper function virLXCControllerSetupUserns, in this function, we set the files uid_map and gid_map of process libvirt_lxc. lxcContainerSetUserns is used for creating cred for tasks running in container. Since after setuid/setgid, we may be a new user. This patch calls lxcContainerSetUserns at first to make sure the new created files belong to right user. Signed-off-by: Gao feng <gaofeng(a)cn.fujitsu.com&gt; --- src/lxc/lxc_container.c | 55 ++++++++++++++++++++++++++++++---------- src/lxc/lxc_controller.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 107 insertions(+), 14 deletions(-) diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c index 1d7bc1e..5c66ae3 100644 --- a/src/lxc/lxc_container.c +++ b/src/lxc/lxc_container.c @@ -329,6 +329,29 @@ int lxcContainerWaitForContinue(int control) /** + * lxcContainerSetUserns: + * + * This function calls setuid and setgid to create proper + * cred for tasks running in container. + * + * Returns 0 on success or -1 in case of error + */ +static int lxcContainerSetUserns(virDomainDefPtr def) +{ + if (def->os.userns != VIR_DOMAIN_USER_NS_ENABLED) + return 0; + + if (virSetUIDGID(def->os.uidmap.first, + def->os.gidmap.first) < 0) { + virReportSystemError(errno, "%s", + _("setuid or setgid failed")); + return -1; + } + + return 0; +}

@@ -2221,6 +2244,24 @@ static int lxcContainerChild(void *data) } } + if (!virFileExists(vmDef->os.init)) { + virReportSystemError(errno, + _("cannot find init path '%s' relative to container root"), + vmDef->os.init); + goto cleanup; + } + + /* Wait for interface devices to show up */ + if (lxcContainerWaitForContinue(argv->monitor) < 0) { + virReportSystemError(errno, "%s", + _("Failed to read the container continue message")); + goto cleanup; + } + VIR_DEBUG("Received container continue message");

+ + if (lxcContainerSetUserns(vmDef) < 0) + goto cleanup; + VIR_DEBUG("Container TTY path: %s", ttyPath); ttyfd = open(ttyPath, O_RDWR|O_NOCTTY); @@ -2236,20 +2277,6 @@ static int lxcContainerChild(void *data) argv->securityDriver) < 0) goto cleanup; - if (!virFileExists(vmDef->os.init)) { - virReportSystemError(errno, - _("cannot find init path '%s' relative to container root"), - vmDef->os.init); - goto cleanup; - } - - /* Wait for interface devices to show up */ - if (lxcContainerWaitForContinue(argv->monitor) < 0) { - virReportSystemError(errno, "%s", - _("Failed to read the container continue message")); - goto cleanup; - } - VIR_DEBUG("Received container continue message"); /* rename and enable interfaces */ if (lxcContainerRenameAndEnableInterfaces(!!(vmDef->features & diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c index 15aa334..f17142f 100644 --- a/src/lxc/lxc_controller.c +++ b/src/lxc/lxc_controller.c @@ -1028,6 +1028,69 @@ cleanup2: } +/** + * virLXCControllerSetupUserns + * + * Set proc files for user namespace + * + * Returns 0 on success or -1 in case of error + */ +static int virLXCControllerSetupUserns(virLXCControllerPtr ctrl) +{ + char *uid_map = NULL; + char *gid_map = NULL; + char *uidmap_value = NULL; + char *gidmap_value = NULL; + int ret = -1; + + if (ctrl->def->os.userns != VIR_DOMAIN_USER_NS_ENABLED) + return 0; + + if (virAsprintf(&uid_map, "/proc/%d/uid_map", ctrl->initpid) < 0) + goto cleanup; + + if (virAsprintf(&gid_map, "/proc/%d/gid_map", ctrl->initpid) < 0) + goto cleanup; + + if (virAsprintf(&uidmap_value, "%u %u %u", + ctrl->def->os.uidmap.first, + ctrl->def->os.uidmap.low_first, + ctrl->def->os.uidmap.count) < 0) + goto cleanup; + + if (virAsprintf(&gidmap_value, "%u %u %u", + ctrl->def->os.gidmap.first, + ctrl->def->os.gidmap.low_first, + ctrl->def->os.gidmap.count) < 0) + goto cleanup; + + if (virFileWriteStr(uid_map, uidmap_value, 0) < 0) { + if (errno == -ENOENT) + virReportSystemError(errno, + _("%s doesn't exist, please disable userns"), + uid_map); + virReportSystemError(errno, _("unable write to %s"), uid_map); + goto cleanup; + } + + if (virFileWriteStr(gid_map, gidmap_value, 0) < 0) { + if (errno == -ENOENT) + virReportSystemError(errno, + _("%s doesn't exist, please disable userns"), + gid_map); + virReportSystemError(errno, _("unable write to %s"), gid_map); + goto cleanup; + } + + ret = 0; +cleanup: + VIR_FREE(uidmap_value); + VIR_FREE(gidmap_value); + VIR_FREE(uid_map); + VIR_FREE(gid_map); + return ret; +}