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ns: Support UTS namespace

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Only two fields are modifiable -- hostname and domainname. So
read them on dump and write on restore.

File format is simple --

u32 magic
u32 length of nodename
u8[] nodename string
u32 length of domainname
u8[] domainname string

For OpenVZ we can write the release at the end, but this is later.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
This commit is contained in:
Pavel Emelyanov
2012-01-26 15:28:00 +04:00
committed by Cyrill Gorcunov
parent 3391416a1b
commit 98f4c2e4de
8 changed files with 173 additions and 2 deletions
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154
namespaces.c
View File

@@ -2,6 +2,7 @@
#include <fcntl.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/utsname.h>
#include "util.h"
#include "crtools.h"
#include "syscall.h"
@@ -27,9 +28,57 @@ out:
return ret;
}
static int dump_uts_string(int fd, char *str)
{
int ret;
u32 len;
len = strlen(str);
ret = write_img(fd, &len);
if (ret == 0)
ret = write_img_buf(fd, str, len);
return ret;
}
static int dump_uts_ns(int ns_pid, struct cr_fdset *fdset)
{
int fd, ret;
struct utsname ubuf;
ret = switch_ns(ns_pid, CLONE_NEWUTS, "uts");
if (ret < 0)
return ret;
ret = uname(&ubuf);
if (ret < 0) {
pr_perror("Error calling uname\n");
return ret;
}
fd = fdset->fds[CR_FD_UTSNS];
ret = dump_uts_string(fd, ubuf.nodename);
if (!ret)
ret = dump_uts_string(fd, ubuf.domainname);
return ret;
}
static int do_dump_namespaces(int ns_pid)
{
return 0;
struct cr_fdset *fdset;
int ret;
fdset = cr_fdset_open(ns_pid, CR_FD_DESC_NS, NULL);
if (fdset == NULL)
return -1;
ret = dump_uts_ns(ns_pid, fdset);
close_cr_fdset(&fdset);
return ret;
}
int dump_namespaces(int ns_pid)
@@ -75,6 +124,67 @@ int dump_namespaces(int ns_pid)
return 0;
}
static int prepare_uts_str(int fd, char *n)
{
int ret;
u32 len;
char str[65], path[128];
ret = read_img(fd, &len);
if (ret > 0) {
if (len >= 65) {
pr_err("Corrupted %s\n", n);
return -1;
}
ret = read_img_buf(fd, str, len);
if (ret < 0)
return -1;
str[len] = '\0';
snprintf(path, sizeof(path),
"/proc/sys/kernel/%s", n);
fd = open(path, O_WRONLY);
if (fd < 0) {
pr_perror("Can't open %s\n", path);
return -1;
}
pr_info("Restoging %s to [%s]\n", n, str);
ret = write(fd, str, len);
close(fd);
if (ret != len) {
pr_perror("Can't write %s to %s\n",
str, path);
return -1;
}
ret = 0;
}
return ret;
}
static int prepare_utsns(int pid)
{
int fd, ret;
u32 len;
char str[65];
fd = open_image_ro(CR_FD_UTSNS, pid);
if (fd < 0)
return -1;
ret = prepare_uts_str(fd, "hostname");
if (!ret)
ret = prepare_uts_str(fd, "domainname");
close(fd);
return ret;
}
int prepare_namespace(int pid, unsigned long clone_flags)
{
int ret = 0;
@@ -82,10 +192,52 @@ int prepare_namespace(int pid, unsigned long clone_flags)
pr_info("Restoring namespaces %d flags %lx\n",
pid, clone_flags);
if (clone_flags & CLONE_NEWUTS)
ret = prepare_utsns(pid);
return ret;
}
static void show_uts_string(int fd, char *n)
{
int ret;
u32 len;
char str[65];
ret = read_img(fd, &len);
if (ret > 0) {
if (len >= 65) {
pr_err("Corrupted hostname\n");
return;
}
ret = read_img_buf(fd, str, len);
if (ret < 0)
return;
str[len] = '\0';
pr_info("%s: [%s]\n", n, str);
}
}
void show_utsns(int fd)
{
pr_img_head(CR_FD_UTSNS);
show_uts_string(fd, "hostname");
show_uts_string(fd, "domainname");
pr_img_tail(CR_FD_UTSNS);
}
int try_show_namespaces(int ns_pid)
{
struct cr_fdset *fdset;
fdset = prep_cr_fdset_for_restore(ns_pid, CR_FD_DESC_NS);
if (!fdset)
return -1;
show_utsns(fdset->fds[CR_FD_UTSNS]);
close_cr_fdset(&fdset);
return 0;
}