[RFC][PATCH] ns: Syscalls for better namespace sharing control.

[Daniel Lezcano]

Eric W. Biederman wrote:
> Daniel Lezcano <daniel.lezcano at free.fr> writes:
>
>   
>> Eric W. Biederman wrote:
>>
>> [ ... ]
>>     
>>> I guess my meaning is I was expecting.
>>> child = fork();
>>> if (child == 0) {
>>> 	execve(...);
>>> }
>>> waitpid(child);
>>>
>>> This puts /bin/sh in the container as well.
>>>   
>>>       
>> #include <unistd.h>
>> #include <stdlib.h>
>> #include <stdio.h>
>> #include <syscall.h>
>> #include <sys/types.h>
>> #include <sys/stat.h>
>> #include <fcntl.h>
>> #include <sys/param.h>
>>
>> #define __NR_setns 300
>>
>> int setns(int nstype, int fd)
>> {
>>    return syscall (__NR_setns, nstype, fd);
>> }
>>
>> int main(int argc, char *argv[])
>> {
>>    char path[MAXPATHLEN];
>>    char *ns[] = { "pid", "mnt", "net", "pid", "uts" };
>>    const int size = sizeof(ns) / sizeof(char *);
>>    int fd[size];
>>    int i;
>>    pid_t pid;
>>    if (argc != 3) {
>>        fprintf(stderr, "mynsenter <pid> <command>\n");
>>        exit(1);
>>    }
>>
>>    for (i = 0; i < size; i++) {
>>            sprintf(path, "/proc/%s/ns/%s", argv[1], ns[i]);
>>
>>        fd[i] = open(path, O_RDONLY| FD_CLOEXEC);
>>        if (fd[i] < 0) {
>>            perror("open");
>>            return -1;
>>        }
>>
>>    }
>>    for (i = 0; i < size; i++)
>>        if (setns(0, fd[i])) {
>>            perror("setns");
>>            return -1;
>>        }
>>
>>    pid = fork();
>>    if (!pid) {
>>
>>        fprintf(stderr, "mypid is %d\n", syscall(__NR_getpid));
>>
>>        execve(argv[2], &argv[2], NULL);
>>        perror("execve");
>>
>>    }
>>
>>    if (pid < 0) {
>>        perror("fork");
>>        return -1;
>>    }
>>
>>    if (waitpid(&pid, NULL, 0) < 0) {
>>        perror("waitpid");
>>    }
>>
>>    return 0;
>> }
>>     
>
> &pid ???  Isn't that a type error?
>   
argh ! right :)

Sorry for the noise. Works well now.