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Diffstat (limited to 'src/mount-setup.c')
| -rw-r--r-- | src/mount-setup.c | 422 |
1 files changed, 422 insertions, 0 deletions
diff --git a/src/mount-setup.c b/src/mount-setup.c new file mode 100644 index 000000000..aaffb655e --- /dev/null +++ b/src/mount-setup.c @@ -0,0 +1,422 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2010 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <sys/mount.h> +#include <errno.h> +#include <sys/stat.h> +#include <stdlib.h> +#include <string.h> +#include <libgen.h> +#include <assert.h> +#include <unistd.h> +#include <ftw.h> + +#include "mount-setup.h" +#include "log.h" +#include "macro.h" +#include "util.h" +#include "label.h" +#include "set.h" +#include "strv.h" + +#ifndef TTY_GID +#define TTY_GID 5 +#endif + +typedef struct MountPoint { + const char *what; + const char *where; + const char *type; + const char *options; + unsigned long flags; + bool fatal; +} MountPoint; + +/* The first three entries we might need before SELinux is up. The + * fourth (securityfs) is needed by IMA to load a custom policy. The + * other ones we can delay until SELinux and IMA are loaded. */ +#define N_EARLY_MOUNT 4 + +static const MountPoint mount_table[] = { + { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true }, + { "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true }, + { "devtmpfs", "/dev", "devtmpfs", "mode=755", MS_NOSUID, true }, + { "securityfs", "/sys/kernel/security", "securityfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, false }, + { "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV, true }, + { "devpts", "/dev/pts", "devpts", "mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC, false }, + { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV, true }, + { "tmpfs", "/sys/fs/cgroup", "tmpfs", "mode=755", MS_NOSUID|MS_NOEXEC|MS_NODEV, false }, + { "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd", MS_NOSUID|MS_NOEXEC|MS_NODEV, false }, +}; + +/* These are API file systems that might be mounted by other software, + * we just list them here so that we know that we should ignore them */ + +static const char * const ignore_paths[] = { + "/sys/fs/selinux", + "/selinux", + "/proc/bus/usb" +}; + +bool mount_point_is_api(const char *path) { + unsigned i; + + /* Checks if this mount point is considered "API", and hence + * should be ignored */ + + for (i = 0; i < ELEMENTSOF(mount_table); i ++) + if (path_equal(path, mount_table[i].where)) + return true; + + return path_startswith(path, "/sys/fs/cgroup/"); +} + +bool mount_point_ignore(const char *path) { + unsigned i; + + for (i = 0; i < ELEMENTSOF(ignore_paths); i++) + if (path_equal(path, ignore_paths[i])) + return true; + + return false; +} + +static int mount_one(const MountPoint *p, bool relabel) { + int r; + + assert(p); + + /* Relabel first, just in case */ + if (relabel) + label_fix(p->where, true); + + if ((r = path_is_mount_point(p->where, true)) < 0) + return r; + + if (r > 0) + return 0; + + /* The access mode here doesn't really matter too much, since + * the mounted file system will take precedence anyway. */ + mkdir_p(p->where, 0755); + + log_debug("Mounting %s to %s of type %s with options %s.", + p->what, + p->where, + p->type, + strna(p->options)); + + if (mount(p->what, + p->where, + p->type, + p->flags, + p->options) < 0) { + log_error("Failed to mount %s: %s", p->where, strerror(errno)); + return p->fatal ? -errno : 0; + } + + /* Relabel again, since we now mounted something fresh here */ + if (relabel) + label_fix(p->where, false); + + return 1; +} + +int mount_setup_early(void) { + unsigned i; + int r = 0; + + assert_cc(N_EARLY_MOUNT <= ELEMENTSOF(mount_table)); + + /* Do a minimal mount of /proc and friends to enable the most + * basic stuff, such as SELinux */ + for (i = 0; i < N_EARLY_MOUNT; i ++) { + int j; + + j = mount_one(mount_table + i, false); + if (r == 0) + r = j; + } + + return r; +} + +int mount_cgroup_controllers(char ***join_controllers) { + int r; + FILE *f; + char buf[LINE_MAX]; + Set *controllers; + + /* Mount all available cgroup controllers that are built into the kernel. */ + + f = fopen("/proc/cgroups", "re"); + if (!f) { + log_error("Failed to enumerate cgroup controllers: %m"); + return 0; + } + + controllers = set_new(string_hash_func, string_compare_func); + if (!controllers) { + r = -ENOMEM; + log_error("Failed to allocate controller set."); + goto finish; + } + + /* Ignore the header line */ + (void) fgets(buf, sizeof(buf), f); + + for (;;) { + char *controller; + int enabled = 0; + + if (fscanf(f, "%ms %*i %*i %i", &controller, &enabled) != 2) { + + if (feof(f)) + break; + + log_error("Failed to parse /proc/cgroups."); + r = -EIO; + goto finish; + } + + if (!enabled) { + free(controller); + continue; + } + + r = set_put(controllers, controller); + if (r < 0) { + log_error("Failed to add controller to set."); + free(controller); + goto finish; + } + } + + for (;;) { + MountPoint p; + char *controller, *where, *options; + char ***k = NULL; + + controller = set_steal_first(controllers); + if (!controller) + break; + + if (join_controllers) + for (k = join_controllers; *k; k++) + if (strv_find(*k, controller)) + break; + + if (k && *k) { + char **i, **j; + + for (i = *k, j = *k; *i; i++) { + + if (!streq(*i, controller)) { + char *t; + + t = set_remove(controllers, *i); + if (!t) { + free(*i); + continue; + } + free(t); + } + + *(j++) = *i; + } + + *j = NULL; + + options = strv_join(*k, ","); + if (!options) { + log_error("Failed to join options"); + free(controller); + r = -ENOMEM; + goto finish; + } + + } else { + options = controller; + controller = NULL; + } + + where = strappend("/sys/fs/cgroup/", options); + if (!where) { + log_error("Failed to build path"); + free(options); + r = -ENOMEM; + goto finish; + } + + zero(p); + p.what = "cgroup"; + p.where = where; + p.type = "cgroup"; + p.options = options; + p.flags = MS_NOSUID|MS_NOEXEC|MS_NODEV; + p.fatal = false; + + r = mount_one(&p, true); + free(controller); + free(where); + + if (r < 0) { + free(options); + goto finish; + } + + if (r > 0 && k && *k) { + char **i; + + for (i = *k; *i; i++) { + char *t; + + t = strappend("/sys/fs/cgroup/", *i); + if (!t) { + log_error("Failed to build path"); + r = -ENOMEM; + free(options); + goto finish; + } + + r = symlink(options, t); + free(t); + + if (r < 0 && errno != EEXIST) { + log_error("Failed to create symlink: %m"); + r = -errno; + free(options); + goto finish; + } + } + } + + free(options); + } + + r = 0; + +finish: + set_free_free(controllers); + + fclose(f); + + return r; +} + +static int symlink_and_label(const char *old_path, const char *new_path) { + int r; + + assert(old_path); + assert(new_path); + + if ((r = label_symlinkfile_set(new_path)) < 0) + return r; + + if (symlink(old_path, new_path) < 0) + r = -errno; + + label_file_clear(); + + return r; +} + +static int nftw_cb( + const char *fpath, + const struct stat *sb, + int tflag, + struct FTW *ftwbuf) { + + /* No need to label /dev twice in a row... */ + if (_unlikely_(ftwbuf->level == 0)) + return FTW_CONTINUE; + + label_fix(fpath, true); + + /* /run/initramfs is static data and big, no need to + * dynamically relabel its contents at boot... */ + if (_unlikely_(ftwbuf->level == 1 && + tflag == FTW_D && + streq(fpath, "/run/initramfs"))) + return FTW_SKIP_SUBTREE; + + return FTW_CONTINUE; +}; + +int mount_setup(bool loaded_policy) { + + static const char symlinks[] = + "/proc/kcore\0" "/dev/core\0" + "/proc/self/fd\0" "/dev/fd\0" + "/proc/self/fd/0\0" "/dev/stdin\0" + "/proc/self/fd/1\0" "/dev/stdout\0" + "/proc/self/fd/2\0" "/dev/stderr\0"; + + static const char relabel[] = + "/run/initramfs/root-fsck\0" + "/run/initramfs/shutdown\0"; + + int r; + unsigned i; + const char *j, *k; + + for (i = 0; i < ELEMENTSOF(mount_table); i ++) { + r = mount_one(mount_table + i, true); + + if (r < 0) + return r; + } + + /* Nodes in devtmpfs and /run need to be manually updated for + * the appropriate labels, after mounting. The other virtual + * API file systems like /sys and /proc do not need that, they + * use the same label for all their files. */ + if (loaded_policy) { + usec_t before_relabel, after_relabel; + char timespan[FORMAT_TIMESPAN_MAX]; + + before_relabel = now(CLOCK_MONOTONIC); + + nftw("/dev", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); + nftw("/run", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); + + /* Explicitly relabel these */ + NULSTR_FOREACH(j, relabel) + label_fix(j, true); + + after_relabel = now(CLOCK_MONOTONIC); + + log_info("Relabelled /dev and /run in %s.", + format_timespan(timespan, sizeof(timespan), after_relabel - before_relabel)); + } + + /* Create a few default symlinks, which are normally created + * by udevd, but some scripts might need them before we start + * udevd. */ + NULSTR_FOREACH_PAIR(j, k, symlinks) + symlink_and_label(j, k); + + /* Create a few directories we always want around */ + label_mkdir("/run/systemd", 0755); + label_mkdir("/run/systemd/system", 0755); + + return 0; +} |