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utils: Introduce open_fd_of_real_pid()

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As access to /proc/[pid]/fd/[i] of a task from parent's
user_ns is prohibited, introduce a helper, doing that
via usernsd.

Also, remove BUG_ON() in usernsd, as now it may be used
without input fd parameter.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
This commit is contained in:
Kirill Tkhai 2017-02-23 18:16:02 +03:00 committed by Andrei Vagin
parent 13cba0ca69
commit f9582b0bd3
3 changed files with 32 additions and 5 deletions
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2
criu/include/util.h
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@ -331,4 +331,6 @@ extern int epoll_del_rfd(int epfd, struct epoll_rfd *rfd);
extern int epoll_run_rfds(int epfd, struct epoll_event *evs, int nr_fds, int tmo); extern int epoll_run_rfds(int epfd, struct epoll_event *evs, int nr_fds, int tmo);
extern int epoll_prepare(int nr_events, struct epoll_event **evs); extern int epoll_prepare(int nr_events, struct epoll_event **evs);
extern int open_fd_of_real_pid(pid_t pid, int fd, int flags);
#endif /* __CR_UTIL_H__ */ #endif /* __CR_UTIL_H__ */

5
criu/namespaces.c
View File

@ -1455,11 +1455,6 @@ static int usernsd(int sk)
unsc_msg_pid_fd(&um, &pid, &fd); unsc_msg_pid_fd(&um, &pid, &fd);
pr_debug("uns: daemon calls %p (%d, %d, %x)\n", call, pid, fd, flags); pr_debug("uns: daemon calls %p (%d, %d, %x)\n", call, pid, fd, flags);
if (fd < 0 && flags & UNS_FDOUT) {
pr_err("uns: bad flags/fd %p %d %x\n", call, fd, flags);
BUG();
}
/* /*
* Caller has sent us bare address of the routine it * Caller has sent us bare address of the routine it
* wants to call. Since the caller is fork()-ed from the * wants to call. Since the caller is fork()-ed from the

30
criu/util.c
View File

@ -1386,3 +1386,33 @@ free_events:
xfree(*events); xfree(*events);
return -1; return -1;
} }
static int fn_open_proc_r(void *path, int fd, pid_t pid)
{
return openat(get_service_fd(CR_PROC_FD_OFF), path, O_RDONLY);
}
static int fn_open_proc_w(void *path, int fd, pid_t pid)
{
return openat(get_service_fd(CR_PROC_FD_OFF), path, O_WRONLY);
}
static int fn_open_proc_rw(void *path, int fd, pid_t pid)
{
return openat(get_service_fd(CR_PROC_FD_OFF), path, O_RDWR);
}
int open_fd_of_real_pid(pid_t pid, int fd, int flags)
{
char path[64];
int ret;
ret = sprintf(path, "%d/fd/%d", pid, fd);
if (flags == O_RDONLY)
ret = userns_call(fn_open_proc_r, UNS_FDOUT, path, ret + 1, -1);
else if (flags == O_WRONLY)
ret = userns_call(fn_open_proc_w, UNS_FDOUT, path, ret + 1, -1);
else if (flags == O_RDWR)
ret = userns_call(fn_open_proc_rw, UNS_FDOUT, path, ret + 1, -1);
else
BUG();
return ret;
}