Adapt lxc_setup_console() to bind mount 'console'

Signed-off-by: LiFeng <lifeng68@huawei.com>

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index f5bcb9d2411900388f1f693a1eb9fd275ff0ae52..8397a981b4d3f89d42eca262aebc789d44934d9e 100644 (file)
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -1569,7 +1569,7 @@ static int lxc_setup_dev_console(const struct lxc_rootfs *rootfs,
        if (console->path && !strcmp(console->path, "none"))
                return 0;
 
-       ret = snprintf(path, sizeof(path), "%s/dev/console", rootfs->mount);
+       ret = snprintf(path, sizeof(path), "%s/dev/console", rootfs->path ? rootfs->mount : "");
        if (ret < 0 || (size_t)ret >= sizeof(path))
                return -1;
 
@@ -1584,12 +1584,6 @@ static int lxc_setup_dev_console(const struct lxc_rootfs *rootfs,
                } else {
                        DEBUG("cleared all (%d) mounts from \"%s\"", ret, path);
                }
-
-               ret = unlink(path);
-               if (ret < 0) {
-                       SYSERROR("error unlinking %s", path);
-                       return -errno;
-               }
        }
 
        /* For unprivileged containers autodev or automounts will already have
@@ -1610,7 +1604,7 @@ static int lxc_setup_dev_console(const struct lxc_rootfs *rootfs,
                return -errno;
        }
 
-       if (safe_mount(console->name, path, "none", MS_BIND, 0, rootfs->mount) < 0) {
+       if (safe_mount(console->name, path, "none", MS_BIND, 0, rootfs->path ? rootfs->mount : "") < 0) {
                ERROR("failed to mount '%s' on '%s'", console->name, path);
                return -1;
        }
@@ -1623,11 +1617,14 @@ static int lxc_setup_ttydir_console(const struct lxc_rootfs *rootfs,
                                    const struct lxc_console *console,
                                    char *ttydir)
 {
-       int ret;
+       int ret, fd;
        char path[MAXPATHLEN], lxcpath[MAXPATHLEN];
 
+       if (console->path && !strcmp(console->path, "none"))
+               return 0;
+
        /* create rootfs/dev/<ttydir> directory */
-       ret = snprintf(path, sizeof(path), "%s/dev/%s", rootfs->mount, ttydir);
+       ret = snprintf(path, sizeof(path), "%s/dev/%s", rootfs->path ? rootfs->mount : "", ttydir);
        if (ret < 0 || (size_t)ret >= sizeof(path))
                return -1;
 
@@ -1638,7 +1635,7 @@ static int lxc_setup_ttydir_console(const struct lxc_rootfs *rootfs,
        }
        DEBUG("Created directory for console and tty devices at \"%s\"", path);
 
-       ret = snprintf(lxcpath, sizeof(lxcpath), "%s/dev/%s/console", rootfs->mount, ttydir);
+       ret = snprintf(lxcpath, sizeof(lxcpath), "%s/dev/%s/console", rootfs->path ? rootfs->mount : "", ttydir);
        if (ret < 0 || (size_t)ret >= sizeof(lxcpath))
                return -1;
 
@@ -1650,56 +1647,11 @@ static int lxc_setup_ttydir_console(const struct lxc_rootfs *rootfs,
        if (ret >= 0)
                close(ret);
 
-       ret = snprintf(path, sizeof(path), "%s/dev/console", rootfs->mount);
-       if (ret < 0 || (size_t)ret >= sizeof(lxcpath))
+       ret = snprintf(path, sizeof(path), "%s/dev/console", rootfs->path ? rootfs->mount : "");
+       if (ret < 0 || (size_t)ret >= sizeof(path))
                return -1;
 
-       /* When we are asked to setup a console we remove any previous
-        * /dev/console bind-mounts.
-        */
-       if (console->path && !strcmp(console->path, "none")) {
-               struct stat st;
-               ret = stat(path, &st);
-               if (ret < 0) {
-                       if (errno == ENOENT)
-                               return 0;
-                       SYSERROR("failed stat() \"%s\"", path);
-                       return -errno;
-               }
-
-               /* /dev/console must be character device with major number 5 and
-                * minor number 1. If not, give benefit of the doubt and assume
-                * the user has mounted something else right there on purpose.
-                */
-               if (((st.st_mode & S_IFMT) != S_IFCHR) || major(st.st_rdev) != 5 || minor(st.st_rdev) != 1)
-                       return 0;
-
-               /* In case the user requested a bind-mount for /dev/console and
-                * requests a ttydir we move the mount to the
-                * /dev/<ttydir/console.
-                * Note, we only move the uppermost mount and clear all other
-                * mounts underneath for safety.
-                * If it is a character device created via mknod() we simply
-                * rename it.
-                */
-               ret = safe_mount(path, lxcpath, "none", MS_MOVE, NULL, rootfs->mount);
-               if (ret < 0) {
-                       if (errno != EINVAL) {
-                               ERROR("failed to MS_MOVE \"%s\" to \"%s\": %s", path, lxcpath, strerror(errno));
-                               return -errno;
-                       }
-                       /* path was not a mountpoint */
-                       ret = rename(path, lxcpath);
-                       if (ret < 0) {
-                               ERROR("failed to rename \"%s\" to \"%s\": %s", path, lxcpath, strerror(errno));
-                               return -errno;
-                       }
-                       DEBUG("renamed \"%s\" to \"%s\"", path, lxcpath);
-               } else {
-                       DEBUG("moved mount \"%s\" to \"%s\"", path, lxcpath);
-               }
-
-               /* Clear all remaining bind-mounts. */
+       if (file_exists(path)) {
                ret = lxc_unstack_mountpoint(path, false);
                if (ret < 0) {
                        ERROR("failed to unmount \"%s\": %s", path, strerror(errno));
@@ -1707,53 +1659,45 @@ static int lxc_setup_ttydir_console(const struct lxc_rootfs *rootfs,
                } else {
                        DEBUG("cleared all (%d) mounts from \"%s\"", ret, path);
                }
-       } else {
-               if (file_exists(path)) {
-                       ret = lxc_unstack_mountpoint(path, false);
-                       if (ret < 0) {
-                               ERROR("failed to unmount \"%s\": %s", path, strerror(errno));
-                               return -ret;
-                       } else {
-                               DEBUG("cleared all (%d) mounts from \"%s\"", ret, path);
-                       }
-               }
+       }
 
-               if (safe_mount(console->name, lxcpath, "none", MS_BIND, 0, rootfs->mount) < 0) {
-                       ERROR("failed to mount '%s' on '%s'", console->name, lxcpath);
-                       return -1;
+       fd = open(path, O_CREAT | O_EXCL, S_IXUSR | S_IXGRP | S_IXOTH);
+       if (fd < 0) {
+               if (errno != EEXIST) {
+                       SYSERROR("failed to create console");
+                       return -errno;
                }
-               DEBUG("mounted \"%s\" onto \"%s\"", console->name, lxcpath);
+       } else {
+               close(fd);
        }
 
-       /* create symlink from rootfs /dev/console to '<ttydir>/console' */
-       ret = snprintf(lxcpath, sizeof(lxcpath), "%s/console", ttydir);
-       if (ret < 0 || (size_t)ret >= sizeof(lxcpath))
-               return -1;
-
-       ret = unlink(path);
-       if (ret && errno != ENOENT) {
-               SYSERROR("error unlinking %s", path);
+       if (chmod(console->name, S_IXUSR | S_IXGRP | S_IXOTH)) {
+               SYSERROR("failed to set mode '0%o' to '%s'", S_IXUSR | S_IXGRP | S_IXOTH, console->name);
                return -errno;
        }
 
-       ret = symlink(lxcpath, path);
-       if (ret < 0) {
-               SYSERROR("failed to create symlink for console from \"%s\" to \"%s\"", lxcpath, path);
+       /* bind mount console->name to '/dev/<ttydir>/console' */
+       if (safe_mount(console->name, lxcpath, "none", MS_BIND, 0, rootfs->path ? rootfs->mount : "") < 0) {
+               ERROR("failed to mount '%s' on '%s'", console->name, lxcpath);
                return -1;
        }
+       DEBUG("mounted \"%s\" onto \"%s\"", console->name, lxcpath);
+
+       /* bind mount '/dev/<ttydir>/console'  to '/dev/console'  */
+       if (safe_mount(lxcpath, path, "none", MS_BIND, 0, rootfs->path ? rootfs->mount : "") < 0) {
+               ERROR("failed to mount '%s' on '%s'", console->name, lxcpath);
+               return -1;
+       }
+       DEBUG("mounted \"%s\" onto \"%s\"", console->name, lxcpath);
+
+       DEBUG("console has been setup under \"%s\" and mounted to \"%s\"", lxcpath, path);
 
-       DEBUG("console has been setup under \"%s\" and symlinked to \"%s\"", lxcpath, path);
        return 0;
 }
 
 static int lxc_setup_console(const struct lxc_rootfs *rootfs,
                             const struct lxc_console *console, char *ttydir)
 {
-       /* We don't have a rootfs, /dev/console will be shared. */
-       if (!rootfs->path) {
-               DEBUG("/dev/console will be shared with the host");
-               return 0;
-       }
 
        if (!ttydir)
                return lxc_setup_dev_console(rootfs, console);