From 06c17c39a8345deef1ecff4dd5ef262f968c9be2 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Wed, 11 Jun 2014 00:44:30 +0200 Subject: [PATCH] nspawn: add new --tmpfs= option to mount a tmpfs on specific directories, such as /var --- man/systemd-nspawn.xml | 24 +++++++++++ src/nspawn/nspawn.c | 94 ++++++++++++++++++++++++++++++++++++------ 2 files changed, 105 insertions(+), 13 deletions(-) diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml index ccd3436d424..d6687038af6 100644 --- a/man/systemd-nspawn.xml +++ b/man/systemd-nspawn.xml @@ -503,6 +503,30 @@ mounts. + + + + Mount a tmpfs file + system into the container. Takes a + single absolute path argument that + specifies where to mount the tmpfs + instance to (in which case the + directory access mode will be chosen + as 0755, owned by root/root), or + optionally a colon-separated pair of + path and mount option string, that is + used for mounting (in which case the + kernel default for access mode and + owner will be chosen, unless otherwise + specified). This option is + particularly useful for mounting + directories such as + /var as tmpfs, to + allow state-less systems, in + particular when combined with + . + + diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c index 867cf192678..29ddfbb1ffc 100644 --- a/src/nspawn/nspawn.c +++ b/src/nspawn/nspawn.c @@ -146,6 +146,7 @@ static uint64_t arg_retain = (1ULL << CAP_MKNOD); static char **arg_bind = NULL; static char **arg_bind_ro = NULL; +static char **arg_tmpfs = NULL; static char **arg_setenv = NULL; static bool arg_quiet = false; static bool arg_share_system = false; @@ -200,6 +201,7 @@ static int help(void) { " --bind=PATH[:PATH] Bind mount a file or directory from the host into\n" " the container\n" " --bind-ro=PATH[:PATH] Similar, but creates a read-only bind mount\n" + " --tmpfs=PATH:[OPTIONS] Mount an empty tmpfs to the specified directory\n" " --setenv=NAME=VALUE Pass an environment variable to PID 1\n" " --share-system Share system namespaces with host\n" " --register=BOOLEAN Register container as machine\n" @@ -222,6 +224,7 @@ static int parse_argv(int argc, char *argv[]) { ARG_LINK_JOURNAL, ARG_BIND, ARG_BIND_RO, + ARG_TMPFS, ARG_SETENV, ARG_SHARE_SYSTEM, ARG_REGISTER, @@ -247,6 +250,7 @@ static int parse_argv(int argc, char *argv[]) { { "link-journal", required_argument, NULL, ARG_LINK_JOURNAL }, { "bind", required_argument, NULL, ARG_BIND }, { "bind-ro", required_argument, NULL, ARG_BIND_RO }, + { "tmpfs", required_argument, NULL, ARG_TMPFS }, { "machine", required_argument, NULL, 'M' }, { "slice", required_argument, NULL, 'S' }, { "setenv", required_argument, NULL, ARG_SETENV }, @@ -469,6 +473,42 @@ static int parse_argv(int argc, char *argv[]) { break; } + case ARG_TMPFS: { + _cleanup_free_ char *a = NULL, *b = NULL; + char *e; + + e = strchr(optarg, ':'); + if (e) { + a = strndup(optarg, e - optarg); + b = strdup(e + 1); + } else { + a = strdup(optarg); + b = strdup("mode=0755"); + } + + if (!a || !b) + return log_oom(); + + if (!path_is_absolute(a)) { + log_error("Invalid tmpfs specification: %s", optarg); + return -EINVAL; + } + + r = strv_push(&arg_tmpfs, a); + if (r < 0) + return log_oom(); + + a = NULL; + + r = strv_push(&arg_tmpfs, b); + if (r < 0) + return log_oom(); + + b = NULL; + + break; + } + case ARG_SETENV: { char **n; @@ -561,17 +601,17 @@ static int mount_all(const char *dest) { } MountPoint; static const MountPoint mount_table[] = { - { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true }, - { "/proc/sys", "/proc/sys", NULL, NULL, MS_BIND, true }, /* Bind mount first */ - { NULL, "/proc/sys", NULL, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */ - { "sysfs", "/sys", "sysfs", NULL, MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV, true }, - { "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID|MS_STRICTATIME, true }, + { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true }, + { "/proc/sys", "/proc/sys", NULL, NULL, MS_BIND, true }, /* Bind mount first */ + { NULL, "/proc/sys", NULL, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */ + { "sysfs", "/sys", "sysfs", NULL, MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV, true }, + { "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID|MS_STRICTATIME, true }, { "devpts", "/dev/pts", "devpts","newinstance,ptmxmode=0666,mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC, true }, - { "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true }, - { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true }, + { "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true }, + { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true }, #ifdef HAVE_SELINUX - { "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL, MS_BIND, false }, /* Bind mount first */ - { NULL, "/sys/fs/selinux", NULL, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, false }, /* Then, make it r/o */ + { "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL, MS_BIND, false }, /* Bind mount first */ + { NULL, "/sys/fs/selinux", NULL, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, false }, /* Then, make it r/o */ #endif }; @@ -640,7 +680,7 @@ static int mount_binds(const char *dest, char **l, bool ro) { char **x, **y; STRV_FOREACH_PAIR(x, y, l) { - char *where; + _cleanup_free_ char *where = NULL; struct stat source_st, dest_st; int r; @@ -649,12 +689,14 @@ static int mount_binds(const char *dest, char **l, bool ro) { return -errno; } - where = strappenda(dest, *y); + where = strappend(dest, *y); + if (!where) + return log_oom(); + r = stat(where, &dest_st); if (r == 0) { if ((source_st.st_mode & S_IFMT) != (dest_st.st_mode & S_IFMT)) { - log_error("The file types of %s and %s do not match. Refusing bind mount", - *x, where); + log_error("The file types of %s and %s do not match. Refusing bind mount", *x, where); return -EINVAL; } } else if (errno == ENOENT) { @@ -667,6 +709,7 @@ static int mount_binds(const char *dest, char **l, bool ro) { log_error("Failed to bind mount %s: %m", *x); return -errno; } + /* Create the mount point, but be conservative -- refuse to create block * and char devices. */ if (S_ISDIR(source_st.st_mode)) @@ -699,6 +742,27 @@ static int mount_binds(const char *dest, char **l, bool ro) { return 0; } +static int mount_tmpfs(const char *dest) { + char **i, **o; + + STRV_FOREACH_PAIR(i, o, arg_tmpfs) { + _cleanup_free_ char *where = NULL; + + where = strappend(dest, *i); + if (!where) + return log_oom(); + + mkdir_label(where, 0755); + + if (mount("tmpfs", where, "tmpfs", MS_NODEV|MS_STRICTATIME, *o) < 0) { + log_error("tmpfs mount to %s failed: %m", where); + return -errno; + } + } + + return 0; +} + static int setup_timezone(const char *dest) { _cleanup_free_ char *where = NULL, *p = NULL, *q = NULL, *check = NULL, *what = NULL; char *z, *y; @@ -2998,6 +3062,9 @@ int main(int argc, char *argv[]) { if (mount_binds(arg_directory, arg_bind_ro, true) < 0) goto child_fail; + if (mount_tmpfs(arg_directory) < 0) + goto child_fail; + if (setup_kdbus(arg_directory, kdbus_domain) < 0) goto child_fail; @@ -3248,6 +3315,7 @@ finish: strv_free(arg_network_macvlan); strv_free(arg_bind); strv_free(arg_bind_ro); + strv_free(arg_tmpfs); return r; }