On Wed, Mar 22, 2017 at 06:08:01PM +0700, Nikolay Marchuk wrote: > Test was rewritten, now it is based on example from > https://lists.gt.net/linux/kernel/2606267.
Please note that if it's code is based on that example, it has to be
reflected in the copyright header.
> New test passed on 4.11-rc2 kernel.
Nice.
[...]
> diff --git a/nsfs.c b/nsfs.c
> new file mode 100644
> index 0000000..bf12248
> --- /dev/null
> +++ b/nsfs.c
> @@ -0,0 +1,94 @@
> +/*
> + * Support for decoding of NS_* ioctl commands.
[...]
> +#include "defs.h"
> +
> +#include <linux/ioctl.h>
> +
> +/* Definitions for commands */
> +#ifdef HAVE_LINUX_NSFS_H
> +# include <linux/nsfs.h>
> +#else
> +# ifndef NSIO
> +# define NSIO 0xb7
> +# endif
> +# ifndef NS_GET_USERNS
> +# define NS_GET_USERNS _IO(NSIO, 0x1)
> +# endif
> +# ifndef NS_GET_PARENT
> +# define NS_GET_PARENT _IO(NSIO, 0x2)
> +# endif
> +#endif
> +
> +#ifndef NS_GET_NSTYPE
> +# define NS_GET_NSTYPE _IO(NSIO, 0x3)
> +#endif
> +#ifndef NS_GET_OWNER_UID
> +# define NS_GET_OWNER_UID _IO(NSIO, 0x4)
> +#endif
The same code is repeated verbatim in the test, which means that
it has to be moved into a separate header file.
> +#include <sys/types.h>
This is already included by "defs.h".
> +#include "xlat/setns_types.h"
> +
> +int
> +nsfs_ioctl(struct tcb *tcp, unsigned int code, kernel_ulong_t arg)
> +{
> + const char *outstr;
> + uid_t uid;
> + if (entering(tcp)) {
> + switch (code) {
> + case NS_GET_USERNS:
> + case NS_GET_PARENT:
> + return RVAL_DECODED | (1 + RVAL_FD);
A simple "return 1 + RVAL_DECODED + RVAL_FD;" would suffice.
> + default:
> + return 0;
> + }
> + } else {
> + switch (code) {
> + case NS_GET_NSTYPE:
> + if (!syserror(tcp)) {
> + outstr = xlookup(setns_types, tcp->u_rval);
> + if (outstr) {
> + tcp->auxstr = outstr;
> + return 1 + RVAL_STR;
> + }
> + }
> + return 1 + RVAL_DECIMAL;
A simple "return 1;" would suffice.
> + case NS_GET_OWNER_UID:
> + tprints(", ");
> + if (!umove_or_printaddr(tcp, arg, &uid)) {
> + printuid("[", uid);
> + tprints("]");
> + }
> + return 1 + RVAL_DECIMAL;
Likewise.
> + default:
> + return 0;
> + }
I think this parser would look simpler if you moved the "entering" check
inside the switch statement, e.g.
switch (code) {
case NS_GET_USERNS:
case NS_GET_PARENT:
return 1 + RVAL_DECODED + RVAL_FD;
case NS_GET_NSTYPE:
if (entering)
return 0;
...
case NS_GET_OWNER_UID:
if (entering)
return 0;
...
default:
return RVAL_DECODED;
}
[...]
> +static void
> +test_clone(pid_t pid)
> +{
> + int ns_fd, userns_fd, parent_ns_fd, nstype, rc;
> + const char *errstr;
> + char path[PATH_MAX];
Why have you chosen PATH_MAX here?
> + uid_t uid;
> +
> + snprintf(path, sizeof(path), "/proc/%d/ns/user", pid);
> + ns_fd = open(path, O_RDONLY);
> + if (ns_fd == -1)
> + perror_msg_and_skip("Open user namespace file error");
We prefer the following format:
perror_msg_and_skip("open: %s", path);
> + userns_fd = ioctl(ns_fd, NS_GET_USERNS);
> + errstr = sprintrc(userns_fd);
> + printf("ioctl(%d, NS_GET_USERNS) = %s\n", ns_fd, errstr);
No need to save sprintrc return code to errstr if it's not necessary.
The same statement could be written as
printf("ioctl(%d, NS_GET_USERNS) = %s\n", ns_fd, sprintrc(userns_fd);
> + parent_ns_fd = ioctl(userns_fd, NS_GET_PARENT);
> + errstr = sprintrc(parent_ns_fd);
> + printf("ioctl(%d, NS_GET_PARENT) = %s\n", userns_fd, errstr);
Likewise.
> + nstype = ioctl(userns_fd, NS_GET_NSTYPE);
> + errstr = sprintrc(nstype);
> + if (nstype == CLONE_NEWUSER) {
> + printf("ioctl(%d, NS_GET_NSTYPE) = %d (CLONE_NEWUSER)\n",
> userns_fd,
> + nstype);
This is not the best choice of wrapping.
> + } else {
> + printf("ioctl(%d, NS_GET_NSTYPE) = %s\n", userns_fd, errstr);
> + }
> +
> + rc = ioctl(userns_fd, NS_GET_OWNER_UID, &uid);
Use uid obtained using TAIL_ALLOC_OBJECT_CONST_PTR instead of an object
placed on the stack.
> + errstr = sprintrc(rc);
> + if (rc == -1) {
> + printf("ioctl(%d, NS_GET_OWNER_UID, %p) = %s\n", userns_fd,
> &uid,
> + errstr);
> + } else {
> + printf("ioctl(%d, NS_GET_OWNER_UID, [", userns_fd);
> + if ((uid_t) -1U == (uid_t) uid)
> + printf("-1]) = %s\n", errstr);
> + else
> + printf("%u]) = %s\n", uid, errstr);
> + }
Do we ever expect an uid == -1?
> +}
> +
> +static int
> +childFunc(void *arg)
Just call it child.
> +{
> + sleep(5);
Why 5? Why sleep? It's not the best way of synchronization.
> + return 0;
> +}
> +
> +#define STACK_SIZE (1024 * 1024)
> +
> +static void
> +test_user_namespace(void)
> +{
> + char *stack;
> + pid_t pid;
> +
> + stack = malloc(STACK_SIZE);
> + if (stack == NULL) {
> + perror_msg_and_skip("Malloc error");
> + }
Why malloc instead of a static chunk of memory?
> + pid = clone(childFunc, stack + STACK_SIZE, CLONE_NEWUSER |
> CLONE_UNTRACED,
> + NULL);
> + if (pid == -1)
> + perror_msg_and_skip("Clone error");
No need to append "error" to every error message.
A simple "clone" would suffice.
> + test_clone(pid);
> + kill(pid, SIGKILL);
sleep+kill is a very rough synchronisation method, could you think
of something more robust, e.g. pipe/read/close/wait?
--
ldv
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