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根創建網絡命名空間testns，並使用CLONE_NEWUSER克隆標誌以獲取用戶命名空間內的子項。然後，小孩試圖通過呼叫setns加入testns，這表明拒絕了權限。 是否有任何其他方法讓用戶名空間內的子節點加入網絡名稱空間？從用戶命名空間內加入網絡命名空間
就寫了這以下測試：（運行之前，我通過調用sudo ip netns add testns創建testns）
#define _GNU_SOURCE
#include <sched.h>
#include <stdlib.h>
#include <signal.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#define STACK_SIZE (1024 * 1024)
static char child_stack[STACK_SIZE];
static void update_map(char *mapping, char *map_file) {
int fd, j;
size_t map_len;
map_len = strlen(mapping);
for (j = 0; j < map_len; j++)
if (mapping[j] == ',')
mapping[j] = '\n';
fd = open(map_file, O_RDWR);
if (fd == -1) {
fprintf(stderr, "open %s: %s\n", map_file, strerror(errno));
exit(EXIT_FAILURE);
}
if (write(fd, mapping, map_len) != map_len) {
fprintf(stderr, "write %s: %s\n", map_file, strerror(errno));
exit(EXIT_FAILURE);
}
close(fd);
}
static void proc_setgroups_write(pid_t child_pid, char *str) {
char setgroups_path[PATH_MAX];
int fd;
snprintf(setgroups_path, PATH_MAX, "/proc/%ld/setgroups",
(long) child_pid);
fd = open(setgroups_path, O_RDWR);
if (fd == -1) {
if (errno != ENOENT)
fprintf(stderr, "ERROR: open %s: %s\n", setgroups_path,
strerror(errno));
return;
}
if (write(fd, str, strlen(str)) == -1)
fprintf(stderr, "ERROR: write %s: %s\n", setgroups_path,
strerror(errno));
close(fd);
}
static void update_userns(pid_t pid, char *uidMap, char *gidMap) {
char map_path[PATH_MAX];
snprintf(map_path, PATH_MAX, "/proc/%ld/uid_map", (long) pid);
update_map(uidMap, map_path);
proc_setgroups_write(pid, "deny");
snprintf(map_path, PATH_MAX, "/proc/%ld/gid_map", (long) pid);
update_map(gidMap, map_path);
}
static int join_netns(char *netns_name) {
char netns_path[256];
snprintf(netns_path, sizeof(netns_path), "/var/run/netns/%s", netns_name);
int fd = open(netns_path, O_RDONLY);
if (fd == -1) {
fprintf(stderr, "open netns path failed: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
if (setns(fd, CLONE_NEWNET) == -1) {
fprintf(stderr, "set netns failed: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
return 0;
}
static int child(void* arg) {
// Sleep so that userns has the correct mapping.
sleep(1);
return join_netns("testns");
}
int main(int argc, char *argv[]) {
uid_t uid = getuid();
char mapping[10];
snprintf(mapping, 10, "0 %d 1", uid);
int pid1 = clone(child, child_stack + STACK_SIZE, CLONE_NEWUSER | SIGCHLD, NULL);
if (pid1 == -1) {
perror("Clone");
exit(EXIT_FAILURE);
}
update_userns(pid1, mapping, mapping);
if (waitpid(pid1, NULL, 0) == -1) {
perror("waitpid");
exit(EXIT_FAILURE);
}
}