96 lines
2.3 KiB
C
96 lines
2.3 KiB
C
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#include "prototype.h"
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#define __USE_GNU
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#define _GNU_SOURCE
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#include <sched.h>
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#include <stdarg.h>
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#include <signal.h>
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#include <errno.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <string.h>
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#include <sys/mount.h>
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#include <sys/syscall.h>
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#include <sys/stat.h>
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#define STACKSIZE (1024 * 1024)
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static char child_stack[STACKSIZE];
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/**
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* child_exec is the func that will be executed as the result of clone
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*/
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int child_exec(void *stuff)
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{
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container_t *c = (container_t *)stuff;
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struct clone_args *cloneArgs = &c->cloneArgs;
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if (sethostname(cloneArgs->hostname, strlen(cloneArgs->hostname)) != 0)
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{
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container_error_handler(c, "fail to set new hostname");
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}
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if (execvp(cloneArgs->argv[0], cloneArgs->argv) != 0)
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{
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container_error_handler(c, "failed to execvp arguments\n");
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}
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// we should never reach here!
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exit(EXIT_FAILURE);
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}
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/**
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* container constructor initialize container_t object
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*/
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container_t *initialize_container(struct clone_args cloneArgs)
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{
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container_t *c = (container_t *)malloc(sizeof(container_t));
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// in order new net ns, new mount ns, new hostname ns, new pid ns, child ns
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c->_cloneFlags = CLONE_NEWNET | CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | CLONE_NEWPID | SIGCHLD;
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c->cloneArgs = cloneArgs;
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return c;
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}
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/**
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* launch command into container
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*/
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pid_t run(container_t *c)
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{
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// the result of this call is that our child_exec will be run in another
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// process returning it's pid
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pid_t pid = clone(child_exec, child_stack + STACKSIZE, c->_cloneFlags, c);
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if (pid < 0)
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{
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container_error_handler(c, "failed to run clone");
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}
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// lets wait on our child process here before we, the parent, exits
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if (waitpid(pid, NULL, 0) == -1)
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{
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container_error_handler(c, "failed to wait pid %d", pid);
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exit(EXIT_FAILURE);
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}
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return pid;
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}
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/**
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* handle error occured during container creation
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* this methode permit to call container_destroy
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* before printing error
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* take at last parameter variadic argument
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*/
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void container_error_handler(container_t *c, const char *error_msg, ...)
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{
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va_list arg;
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va_start(arg, error_msg);
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destroy_container(c);
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error(error_msg, arg);
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va_end(arg);
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}
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/**
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* container destructor
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*/
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void destroy_container(container_t *c)
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{
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free(c);
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}
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