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Merge pull request #700 from hallyn/2015-11-17/preserve_ns.2

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Better handle preserve_ns behavior
This commit is contained in:
Stéphane Graber 2015-11-18 00:18:24 -05:00
commit e8f6a15cfa
1 changed files with 34 additions and 13 deletions
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47
src/lxc/start.c
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@ -124,8 +124,15 @@ static void close_ns(int ns_fd[LXC_NS_MAX]) {
} }
} }
static int preserve_ns(int ns_fd[LXC_NS_MAX], int clone_flags, pid_t pid) { /*
int i, saved_errno; * preserve_ns: open /proc/@pid/ns/@ns for each namespace specified
* in clone_flags.
* Return true on success, false on failure. On failure, leave an error
* message in *errmsg, which caller must free.
*/
static
bool preserve_ns(int ns_fd[LXC_NS_MAX], int clone_flags, pid_t pid, char **errmsg) {
int i, ret;
char path[MAXPATHLEN]; char path[MAXPATHLEN];
for (i = 0; i < LXC_NS_MAX; i++) for (i = 0; i < LXC_NS_MAX; i++)
@ -133,8 +140,9 @@ static int preserve_ns(int ns_fd[LXC_NS_MAX], int clone_flags, pid_t pid) {
snprintf(path, MAXPATHLEN, "/proc/%d/ns", pid); snprintf(path, MAXPATHLEN, "/proc/%d/ns", pid);
if (access(path, X_OK)) { if (access(path, X_OK)) {
WARN("Kernel does not support attach; preserve_ns ignored"); if (asprintf(errmsg, "Kernel does not support setns.") == -1)
return 0; *errmsg = NULL;
return false;
} }
for (i = 0; i < LXC_NS_MAX; i++) { for (i = 0; i < LXC_NS_MAX; i++) {
@ -147,14 +155,20 @@ static int preserve_ns(int ns_fd[LXC_NS_MAX], int clone_flags, pid_t pid) {
goto error; goto error;
} }
return 0; return true;
error: error:
saved_errno = errno; if (errno == ENOENT) {
ret = asprintf(errmsg, "Kernel does not support setns for %s",
ns_info[i].proc_name);
} else {
ret = asprintf(errmsg, "Failed to open %s: %s",
path, strerror(errno));
}
if (ret == -1)
*errmsg = NULL;
close_ns(ns_fd); close_ns(ns_fd);
errno = saved_errno; return false;
SYSERROR("failed to open '%s'", path);
return -1;
} }
static int attach_ns(const int ns_fd[LXC_NS_MAX]) { static int attach_ns(const int ns_fd[LXC_NS_MAX]) {
@ -933,6 +947,7 @@ static int lxc_spawn(struct lxc_handler *handler)
{ {
int failed_before_rename = 0; int failed_before_rename = 0;
const char *name = handler->name; const char *name = handler->name;
char *errmsg = NULL;
bool cgroups_connected = false; bool cgroups_connected = false;
int saved_ns_fd[LXC_NS_MAX]; int saved_ns_fd[LXC_NS_MAX];
int preserve_mask = 0, i; int preserve_mask = 0, i;
@ -1007,8 +1022,12 @@ static int lxc_spawn(struct lxc_handler *handler)
INFO("failed to pin the container's rootfs"); INFO("failed to pin the container's rootfs");
} }
if (preserve_ns(saved_ns_fd, preserve_mask, getpid()) < 0) if (!preserve_ns(saved_ns_fd, preserve_mask, getpid(), &errmsg)) {
SYSERROR("Failed to preserve requested namespaces: %s",
errmsg ? errmsg : "(Out of memory)");
free(errmsg);
goto out_delete_net; goto out_delete_net;
}
if (attach_ns(handler->conf->inherit_ns_fd) < 0) if (attach_ns(handler->conf->inherit_ns_fd) < 0)
goto out_delete_net; goto out_delete_net;
@ -1028,9 +1047,11 @@ static int lxc_spawn(struct lxc_handler *handler)
goto out_delete_net; goto out_delete_net;
} }
if (preserve_ns(handler->nsfd, handler->clone_flags, handler->pid) < 0) { if (preserve_ns(handler->nsfd, handler->clone_flags, handler->pid,
ERROR("failed to store namespace references"); &errmsg) < 0) {
goto out_delete_net; INFO("Failed to store namespace references for stop hook: %s",
errmsg ? errmsg : "(Out of memory)");
free(errmsg);
} }
if (attach_ns(saved_ns_fd)) if (attach_ns(saved_ns_fd))