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2884ccd2e7
Having the "subcommand" first is more conventional and will make it more natural for future extensions I have planned. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
140 lines
3.0 KiB
C
140 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* nstool - maintain a namespace to be entered by other processes
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*
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* Copyright Red Hat
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* Author: David Gibson <david@gibson.dropbear.id.au>
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*
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* Can run in 3 modes:
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*
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* nstool hold <path>
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* Designed to be run inside a namespace, opens a Unix domain
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* control socket at <path> and waits until instructed to stop
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* with "nstool stop <path>"
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* nstool pid <path>
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* Prints the PID of the nstool hold process with control socket
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* <path>. This is given in the PID namespace where nstool pid
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* is executed, not the one where nstool hold is running
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* nstool stop <path>
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* Instruct the nstool hold with control socket at <path> to
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* exit.
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*/
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#define _GNU_SOURCE
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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 <errno.h>
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#include <unistd.h>
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#include <sys/socket.h>
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#include <linux/un.h>
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#define die(...) \
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do { \
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fprintf(stderr, __VA_ARGS__); \
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exit(1); \
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} while (0)
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static void usage(void)
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{
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die("Usage: nstool hold|pid|stop <socket path>\n");
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}
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static void hold(int fd, const struct sockaddr_un *addr)
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{
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int rc;
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rc = bind(fd, (struct sockaddr *)addr, sizeof(*addr));
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if (rc < 0)
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die("bind(): %s\n", strerror(errno));
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rc = listen(fd, 0);
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if (rc < 0)
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die("listen(): %s\n", strerror(errno));
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printf("nstool: local PID=%d local UID=%u local GID=%u\n",
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getpid(), getuid(), getgid());
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do {
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int afd = accept(fd, NULL, NULL);
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char buf;
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if (afd < 0)
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die("accept(): %s\n", strerror(errno));
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rc = read(afd, &buf, sizeof(buf));
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if (rc < 0)
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die("read(): %s\n", strerror(errno));
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} while (rc == 0);
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unlink(addr->sun_path);
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}
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static void pid(int fd, const struct sockaddr_un *addr)
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{
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int rc;
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struct ucred peercred;
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socklen_t optlen = sizeof(peercred);
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do {
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rc = connect(fd, (struct sockaddr *)addr, sizeof(*addr));
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if (rc < 0 && errno != ENOENT && errno != ECONNREFUSED)
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die("connect(): %s\n", strerror(errno));
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} while (rc < 0);
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rc = getsockopt(fd, SOL_SOCKET, SO_PEERCRED,
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&peercred, &optlen);
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if (rc < 0)
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die("getsockopet(SO_PEERCRED): %s\n", strerror(errno));
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close(fd);
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printf("%d\n", peercred.pid);
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}
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static void stop(int fd, const struct sockaddr_un *addr)
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{
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int rc;
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char buf = 'Q';
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rc = connect(fd, (struct sockaddr *)addr, sizeof(*addr));
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if (rc < 0)
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die("connect(): %s\n", strerror(errno));
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rc = write(fd, &buf, sizeof(buf));
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if (rc < 0)
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die("write(): %s\n", strerror(errno));
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close(fd);
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}
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int main(int argc, char *argv[])
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{
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int fd;
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const char *sockname;
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struct sockaddr_un sockaddr = {
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.sun_family = AF_UNIX,
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};
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if (argc != 3)
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usage();
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sockname = argv[2];
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strncpy(sockaddr.sun_path, sockname, UNIX_PATH_MAX);
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fd = socket(AF_UNIX, SOCK_STREAM, PF_UNIX);
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if (fd < 0)
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die("socket(): %s\n", strerror(errno));
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if (strcmp(argv[1], "hold") == 0)
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hold(fd, &sockaddr);
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else if (strcmp(argv[1], "pid") == 0)
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pid(fd, &sockaddr);
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else if (strcmp(argv[1], "stop") == 0)
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stop(fd, &sockaddr);
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else
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usage();
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exit(0);
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}
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