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1fde6f21d9
/proc entries under /proc/net/* can't be cached into dcache because
setns(2) can change current net namespace.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: avoid vim miscolorization]
[adobriyan@gmail.com: write test, add dummy ->d_revalidate hook: necessary if /proc/net/* is pinned at setns time]
Link: http://lkml.kernel.org/r/20190108192350.GA12034@avx2
Link: http://lkml.kernel.org/r/20190107162336.GA9239@avx2
Fixes: 1da4d377f9 ("proc: revalidate misc dentries")
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reported-by: Mateusz Stępień <mateusz.stepien@netrounds.com>
Reported-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
130 lines
2.6 KiB
C
130 lines
2.6 KiB
C
/*
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* Copyright © 2019 Alexey Dobriyan <adobriyan@gmail.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* Test that setns(CLONE_NEWNET) points to new /proc/net content even
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* if old one is in dcache.
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*
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* FIXME /proc/net/unix is under CONFIG_UNIX which can be disabled.
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*/
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#undef NDEBUG
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#include <assert.h>
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#include <errno.h>
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#include <sched.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <sys/socket.h>
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static pid_t pid = -1;
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static void f(void)
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{
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if (pid > 0) {
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kill(pid, SIGTERM);
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}
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}
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int main(void)
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{
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int fd[2];
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char _ = 0;
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int nsfd;
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atexit(f);
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/* Check for priviledges and syscall availability straight away. */
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if (unshare(CLONE_NEWNET) == -1) {
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if (errno == ENOSYS || errno == EPERM) {
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return 4;
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}
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return 1;
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}
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/* Distinguisher between two otherwise empty net namespaces. */
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if (socket(AF_UNIX, SOCK_STREAM, 0) == -1) {
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return 1;
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}
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if (pipe(fd) == -1) {
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return 1;
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}
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pid = fork();
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if (pid == -1) {
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return 1;
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}
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if (pid == 0) {
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if (unshare(CLONE_NEWNET) == -1) {
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return 1;
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}
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if (write(fd[1], &_, 1) != 1) {
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return 1;
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}
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pause();
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return 0;
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}
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if (read(fd[0], &_, 1) != 1) {
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return 1;
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}
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{
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char buf[64];
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snprintf(buf, sizeof(buf), "/proc/%u/ns/net", pid);
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nsfd = open(buf, O_RDONLY);
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if (nsfd == -1) {
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return 1;
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}
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}
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/* Reliably pin dentry into dcache. */
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(void)open("/proc/net/unix", O_RDONLY);
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if (setns(nsfd, CLONE_NEWNET) == -1) {
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return 1;
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}
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kill(pid, SIGTERM);
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pid = 0;
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{
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char buf[4096];
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ssize_t rv;
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int fd;
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fd = open("/proc/net/unix", O_RDONLY);
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if (fd == -1) {
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return 1;
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}
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#define S "Num RefCount Protocol Flags Type St Inode Path\n"
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rv = read(fd, buf, sizeof(buf));
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assert(rv == strlen(S));
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assert(memcmp(buf, S, strlen(S)) == 0);
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}
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return 0;
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}
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