From c6ac7e4b98828b3b9ea5bd510cf8cc3c25dc2e58 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Tue, 10 Mar 2015 18:58:10 +0100 Subject: machine-id-setup: simplifications --- src/core/machine-id-setup.c | 282 ++++++++++++++++++++++---------------------- 1 file changed, 140 insertions(+), 142 deletions(-) (limited to 'src/core') diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c index 623dffdea..7505dcbca 100644 --- a/src/core/machine-id-setup.c +++ b/src/core/machine-id-setup.c @@ -40,6 +40,12 @@ static int shorten_uuid(char destination[34], const char source[36]) { unsigned i, j; + assert(destination); + assert(source); + + /* Converts a UUID into a machine ID, by lowercasing it and + * removing dashes. Validates everything. */ + for (i = 0, j = 0; i < 36 && j < 32; i++) { int t; @@ -50,16 +56,53 @@ static int shorten_uuid(char destination[34], const char source[36]) { destination[j++] = hexchar(t); } - if (i == 36 && j == 32) { - destination[32] = '\n'; - destination[33] = 0; - return 0; - } + if (i != 36 || j != 32) + return -EINVAL; + + destination[32] = '\n'; + destination[33] = 0; + return 0; +} + +static int read_machine_id(int fd, char id[34]) { + char id_to_validate[34]; + int r; + + assert(fd >= 0); + assert(id); + + /* Reads a machine ID from a file, validates it, and returns + * it. The returned ID ends in a newline. */ + + r = loop_read_exact(fd, id_to_validate, 33, false); + if (r < 0) + return r; + + if (id_to_validate[32] != '\n') + return -EINVAL; + + id_to_validate[32] = 0; + + if (!id128_is_valid(id_to_validate)) + return -EINVAL; + + memcpy(id, id_to_validate, 32); + id[32] = '\n'; + id[33] = 0; + return 0; +} - return -EINVAL; +static int write_machine_id(int fd, char id[34]) { + assert(fd >= 0); + assert(id); + + if (lseek(fd, 0, SEEK_SET) < 0) + return -errno; + + return loop_write(fd, id, 33, false); } -static int generate(char id[34], const char *root) { +static int generate_machine_id(char id[34], const char *root) { int fd, r; unsigned char *p; sd_id128_t buf; @@ -76,18 +119,12 @@ static int generate(char id[34], const char *root) { /* First, try reading the D-Bus machine id, unless it is a symlink */ fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); if (fd >= 0) { - r = loop_read_exact(fd, id, 33, false); + r = read_machine_id(fd, id); safe_close(fd); - if (r >= 0 && id[32] == '\n') { - id[32] = 0; - if (id128_is_valid(id)) { - id[32] = '\n'; - id[33] = 0; - - log_info("Initializing machine ID from D-Bus machine ID."); - return 0; - } + if (r >= 0) { + log_info("Initializing machine ID from D-Bus machine ID."); + return 0; } } @@ -101,12 +138,10 @@ static int generate(char id[34], const char *root) { r = getenv_for_pid(1, "container_uuid", &e); if (r > 0) { - if (strlen(e) >= 36) { - r = shorten_uuid(id, e); - if (r >= 0) { - log_info("Initializing machine ID from container UUID."); - return 0; - } + r = shorten_uuid(id, e); + if (r >= 0) { + log_info("Initializing machine ID from container UUID."); + return 0; } } @@ -154,36 +189,96 @@ static int generate(char id[34], const char *root) { return 0; } -static int get_valid_machine_id(int fd, char id[34]) { - char id_to_validate[34]; +int machine_id_setup(const char *root) { + const char *etc_machine_id, *run_machine_id; + _cleanup_close_ int fd = -1; + bool writable = true; + char id[34]; /* 32 + \n + \0 */ + int r; - assert(fd >= 0); - assert(id); + if (isempty(root)) { + etc_machine_id = "/etc/machine-id"; + run_machine_id = "/run/machine-id"; + } else { + char *x; - if (loop_read_exact(fd, id_to_validate, 33, false) >= 0 && - id_to_validate[32] == '\n') { - id_to_validate[32] = 0; + x = strjoina(root, "/etc/machine-id"); + etc_machine_id = path_kill_slashes(x); - if (id128_is_valid(id_to_validate)) { - memcpy(id, id_to_validate, 32); - id[32] = '\n'; - id[33] = 0; - return 0; - } + x = strjoina(root, "/run/machine-id"); + run_machine_id = path_kill_slashes(x); } - return -EINVAL; -} + RUN_WITH_UMASK(0000) { + /* We create this 0444, to indicate that this isn't really + * something you should ever modify. Of course, since the file + * will be owned by root it doesn't matter much, but maybe + * people look. */ -static int write_machine_id(int fd, char id[34]) { - assert(fd >= 0); - assert(id); - lseek(fd, 0, SEEK_SET); + mkdir_parents(etc_machine_id, 0755); + fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); + if (fd < 0) { + int old_errno = errno; + + fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY); + if (fd < 0) { + if (old_errno == EROFS && errno == ENOENT) + log_error_errno(errno, + "System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n" + "Booting up is supported only when:\n" + "1) /etc/machine-id exists and is populated.\n" + "2) /etc/machine-id exists and is empty.\n" + "3) /etc/machine-id is missing and /etc is writable.\n"); + else + log_error_errno(errno, "Cannot open %s: %m", etc_machine_id); + + return -errno; + } - if (loop_write(fd, id, 33, false) == 0) + writable = false; + } + } + + if (read_machine_id(fd, id) >= 0) return 0; - return -errno; + /* Hmm, so, the id currently stored is not useful, then let's + * generate one */ + + r = generate_machine_id(id, root); + if (r < 0) + return r; + + if (writable) + if (write_machine_id(fd, id) >= 0) + return 0; + + fd = safe_close(fd); + + /* Hmm, we couldn't write it? So let's write it to + * /run/machine-id as a replacement */ + + RUN_WITH_UMASK(0022) { + r = write_string_file(run_machine_id, id); + } + if (r < 0) { + (void) unlink(run_machine_id); + return log_error_errno(r, "Cannot write %s: %m", run_machine_id); + } + + /* And now, let's mount it over */ + if (mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL) < 0) { + (void) unlink_noerrno(run_machine_id); + return log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id); + } + + log_info("Installed transient %s file.", etc_machine_id); + + /* Mark the mount read-only */ + if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0) + log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id); + + return 0; } int machine_id_commit(const char *root) { @@ -214,7 +309,7 @@ int machine_id_commit(const char *root) { if (fd < 0) return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id); - r = get_valid_machine_id(fd, id); + r = read_machine_id(fd, id); if (r < 0) return log_error_errno(r, "We didn't find a valid machine ID in %s.", etc_machine_id); @@ -264,100 +359,3 @@ int machine_id_commit(const char *root) { return 0; } - -int machine_id_setup(const char *root) { - const char *etc_machine_id, *run_machine_id; - _cleanup_close_ int fd = -1; - bool writable = true; - struct stat st; - char id[34]; /* 32 + \n + \0 */ - int r; - - if (isempty(root)) { - etc_machine_id = "/etc/machine-id"; - run_machine_id = "/run/machine-id"; - } else { - char *x; - - x = strjoina(root, "/etc/machine-id"); - etc_machine_id = path_kill_slashes(x); - - x = strjoina(root, "/run/machine-id"); - run_machine_id = path_kill_slashes(x); - } - - RUN_WITH_UMASK(0000) { - /* We create this 0444, to indicate that this isn't really - * something you should ever modify. Of course, since the file - * will be owned by root it doesn't matter much, but maybe - * people look. */ - - mkdir_parents(etc_machine_id, 0755); - fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); - if (fd < 0) { - int old_errno = errno; - - fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY); - if (fd < 0) { - if (old_errno == EROFS && errno == ENOENT) - log_error("System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n" - "Booting up is supported only when:\n" - "1) /etc/machine-id exists and is populated.\n" - "2) /etc/machine-id exists and is empty.\n" - "3) /etc/machine-id is missing and /etc is writable.\n"); - else - log_error_errno(errno, "Cannot open %s: %m", etc_machine_id); - return -errno; - } - - writable = false; - } - } - - if (fstat(fd, &st) < 0) - return log_error_errno(errno, "fstat() failed: %m"); - - if (S_ISREG(st.st_mode) && get_valid_machine_id(fd, id) == 0) - return 0; - - /* Hmm, so, the id currently stored is not useful, then let's - * generate one */ - - r = generate(id, root); - if (r < 0) - return r; - - if (S_ISREG(st.st_mode) && writable) - if (write_machine_id(fd, id) == 0) - return 0; - - fd = safe_close(fd); - - /* Hmm, we couldn't write it? So let's write it to - * /run/machine-id as a replacement */ - - RUN_WITH_UMASK(0022) { - r = write_string_file(run_machine_id, id); - } - if (r < 0) { - log_error_errno(r, "Cannot write %s: %m", run_machine_id); - unlink(run_machine_id); - return r; - } - - /* And now, let's mount it over */ - r = mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL); - if (r < 0) { - log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id); - unlink_noerrno(run_machine_id); - return -errno; - } - - log_info("Installed transient %s file.", etc_machine_id); - - /* Mark the mount read-only */ - if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0) - log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id); - - return 0; -} -- cgit v1.2.3