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author | 2018-11-23 19:47:41 +0100 | |
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committer | 2018-12-18 14:47:44 +0100 | |
commit | 59f13dd6f801b2df4faea277a5de0115ed598e35 (patch) | |
tree | 8acbe9514d02c8b554c4bc67991e9893d99dd64b | |
parent | remount-fs: split code for tracking PIDs in hashmap (diff) | |
download | systemd-59f13dd6f801b2df4faea277a5de0115ed598e35.tar.gz systemd-59f13dd6f801b2df4faea277a5de0115ed598e35.tar.bz2 systemd-59f13dd6f801b2df4faea277a5de0115ed598e35.zip |
remount-fs: optionally remount / writable, if we are told through an env var
-rw-r--r-- | docs/ENVIRONMENT.md | 8 | ||||
-rw-r--r-- | src/remount-fs/remount-fs.c | 90 |
2 files changed, 68 insertions, 30 deletions
diff --git a/docs/ENVIRONMENT.md b/docs/ENVIRONMENT.md index 038f3d2d1..619a57eb3 100644 --- a/docs/ENVIRONMENT.md +++ b/docs/ENVIRONMENT.md @@ -165,3 +165,11 @@ systemd itself: * `$SYSTEMD_ACTIVATION_SCOPE` — closely related to `$SYSTEMD_ACTIVATION_UNIT`, it is either set to `system` or `user` depending on whether the NSS/PAM module is called by systemd in `--system` or `--user` mode. + +systemd-remount-fs: + +* `$SYSTEMD_REMOUNT_ROOT_RW=1` — if set and and no entry for the root directory + exists in /etc/fstab (this file always takes precedence), then the root + directory is remounted writable. This is primarily used by + systemd-gpt-auto-generator to ensure the root partition is mounted writable + in accordance to the GPT partition flags. diff --git a/src/remount-fs/remount-fs.c b/src/remount-fs/remount-fs.c index 88e2b34ac..0bac355e0 100644 --- a/src/remount-fs/remount-fs.c +++ b/src/remount-fs/remount-fs.c @@ -8,6 +8,7 @@ #include <sys/wait.h> #include <unistd.h> +#include "env-util.h" #include "exit-status.h" #include "log.h" #include "main-func.h" @@ -49,6 +50,7 @@ static int track_pid(Hashmap **h, const char *path, pid_t pid) { static int run(int argc, char *argv[]) { _cleanup_hashmap_free_free_ Hashmap *pids = NULL; _cleanup_endmntent_ FILE *f = NULL; + bool has_root = false; struct mntent* me; int r; @@ -62,44 +64,72 @@ static int run(int argc, char *argv[]) { f = setmntent("/etc/fstab", "re"); if (!f) { - if (errno == ENOENT) - return 0; - - return log_error_errno(errno, "Failed to open /etc/fstab: %m"); - } - - while ((me = getmntent(f))) { - pid_t pid; - - /* Remount the root fs, /usr and all API VFS */ - if (!mount_point_is_api(me->mnt_dir) && - !PATH_IN_SET(me->mnt_dir, "/", "/usr")) - continue; - - log_debug("Remounting %s", me->mnt_dir); - - r = safe_fork("(remount)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid); - if (r < 0) - return r; - if (r == 0) { - /* Child */ - - execv(MOUNT_PATH, STRV_MAKE(MOUNT_PATH, me->mnt_dir, "-o", "remount")); + if (errno != ENOENT) + return log_error_errno(errno, "Failed to open /etc/fstab: %m"); + } else { + while ((me = getmntent(f))) { + pid_t pid; + + /* Remount the root fs, /usr and all API VFS */ + if (!mount_point_is_api(me->mnt_dir) && + !PATH_IN_SET(me->mnt_dir, "/", "/usr")) + continue; - log_error_errno(errno, "Failed to execute " MOUNT_PATH ": %m"); - _exit(EXIT_FAILURE); + log_debug("Remounting %s...", me->mnt_dir); + + if (path_equal(me->mnt_dir, "/")) + has_root = true; + + r = safe_fork("(remount)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid); + if (r < 0) + return r; + if (r == 0) { + /* Child */ + execv(MOUNT_PATH, STRV_MAKE(MOUNT_PATH, me->mnt_dir, "-o", "remount")); + log_error_errno(errno, "Failed to execute " MOUNT_PATH ": %m"); + _exit(EXIT_FAILURE); + } + + /* Parent */ + r = track_pid(&pids, me->mnt_dir, pid); + if (r < 0) + return r; } + } - /* Parent */ - r = track_pid(&pids, me->mnt_dir, pid); - if (r < 0) - return r; + if (!has_root) { + /* The $SYSTEMD_REMOUNT_ROOT_RW environment variable is set by systemd-gpt-auto-generator to tell us + * whether to remount things. We honour it only if there's no explicit line in /etc/fstab configured + * which takes precedence. */ + + r = getenv_bool("SYSTEMD_REMOUNT_ROOT_RW"); + if (r > 0) { + pid_t pid; + + log_debug("Remounting / writable..."); + + r = safe_fork("(remount-rw)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG, &pid); + if (r < 0) + return r; + if (r == 0) { + /* Child */ + execv(MOUNT_PATH, STRV_MAKE(MOUNT_PATH, "/", "-o", "remount,rw")); + log_error_errno(errno, "Failed to execute " MOUNT_PATH ": %m"); + _exit(EXIT_FAILURE); + } + + r = track_pid(&pids, "/", pid); + if (r < 0) + return r; + + } else if (r < 0 && r != -ENXIO) + log_warning_errno(r, "Failed to parse $SYSTEMD_REMOUNT_ROOT_RW, ignoring: %m"); } r = 0; while (!hashmap_isempty(pids)) { - siginfo_t si = {}; _cleanup_free_ char *s = NULL; + siginfo_t si = {}; if (waitid(P_ALL, 0, &si, WEXITED) < 0) { if (errno == EINTR) |