[thirdparty/systemd.git] / src / getty-generator / getty-generator.c

/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <errno.h>
#include <fcntl.h>
#include <unistd.h>

#include "alloc-util.h"
#include "errno-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "generator.h"
#include "log.h"
#include "mkdir-label.h"
#include "parse-util.h"
#include "path-util.h"
#include "process-util.h"
#include "proc-cmdline.h"
#include "strv.h"
#include "terminal-util.h"
#include "unit-name.h"
#include "virt.h"

static const char *arg_dest = NULL;
static bool arg_enabled = true;

static int add_symlink(const char *fservice, const char *tservice) {
        char *from, *to;
        int r;

        assert(fservice);
        assert(tservice);

        from = strjoina(SYSTEM_DATA_UNIT_DIR "/", fservice);
        to = strjoina(arg_dest, "/getty.target.wants/", tservice);

        (void) mkdir_parents_label(to, 0755);

        r = symlink(from, to);
        if (r < 0) {
                /* In case console=hvc0 is passed this will very likely result in EEXIST */
                if (errno == EEXIST)
                        return 0;

                return log_error_errno(errno, "Failed to create symlink %s: %m", to);
        }

        return 0;
}

static int add_serial_getty(const char *tty) {
        _cleanup_free_ char *n = NULL;
        int r;

        assert(tty);

        log_debug("Automatically adding serial getty for /dev/%s.", tty);

        r = unit_name_from_path_instance("serial-getty", tty, ".service", &n);
        if (r < 0)
                return log_error_errno(r, "Failed to generate service name: %m");

        return add_symlink("serial-getty@.service", n);
}

static int add_container_getty(const char *tty) {
        _cleanup_free_ char *n = NULL;
        int r;

        assert(tty);

        log_debug("Automatically adding container getty for /dev/pts/%s.", tty);

        r = unit_name_from_path_instance("container-getty", tty, ".service", &n);
        if (r < 0)
                return log_error_errno(r, "Failed to generate service name: %m");

        return add_symlink("container-getty@.service", n);
}

static int verify_tty(const char *name) {
        _cleanup_close_ int fd = -EBADF;
        const char *p;

        /* Some TTYs are weird and have been enumerated but don't work
         * when you try to use them, such as classic ttyS0 and
         * friends. Let's check that and open the device and run
         * isatty() on it. */

        p = strjoina("/dev/", name);

        /* O_NONBLOCK is essential here, to make sure we don't wait
         * for DCD */
        fd = open(p, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC|O_NOFOLLOW);
        if (fd < 0)
                return -errno;

        errno = 0;
        if (isatty(fd) <= 0)
                return errno_or_else(EIO);

        return 0;
}

static int run_container(void) {
        _cleanup_free_ char *container_ttys = NULL;
        int r;

        log_debug("Automatically adding console shell.");

        r = add_symlink("console-getty.service", "console-getty.service");
        if (r < 0)
                return r;

        /* When $container_ttys is set for PID 1, spawn gettys on all ptys named therein.
         * Note that despite the variable name we only support ptys here. */

        (void) getenv_for_pid(1, "container_ttys", &container_ttys);

        for (const char *p = container_ttys;;) {
               _cleanup_free_ char *word = NULL;

                r = extract_first_word(&p, &word, NULL, 0);
                if (r < 0)
                        return log_error_errno(r, "Failed to parse $container_ttys: %m");
                if (r == 0)
                        return 0;

                const char *tty = word;

                /* First strip off /dev/ if it is specified */
                tty = path_startswith(tty, "/dev/") ?: tty;

                /* Then, make sure it's actually a pty */
                tty = path_startswith(tty, "pts/");
                if (!tty)
                        continue;

                r = add_container_getty(tty);
                if (r < 0)
                        return r;
        }
}

static int parse_proc_cmdline_item(const char *key, const char *value, void *data) {
        int r;

        assert(key);

        if (proc_cmdline_key_streq(key, "systemd.getty_auto")) {
                r = value ? parse_boolean(value) : 1;
                if (r < 0)
                        log_warning_errno(r, "Failed to parse getty_auto switch \"%s\", ignoring: %m", value);
                else
                        arg_enabled = r;
        }

        return 0;
}

static int run(const char *dest, const char *dest_early, const char *dest_late) {
        _cleanup_free_ char *getty_auto = NULL;
        int r;

        assert_se(arg_dest = dest);

        r = proc_cmdline_parse(parse_proc_cmdline_item, NULL, 0);
        if (r < 0)
                log_warning_errno(r, "Failed to parse kernel command line, ignoring: %m");

        r = getenv_for_pid(1, "SYSTEMD_GETTY_AUTO", &getty_auto);
        if (r < 0)
                log_warning_errno(r, "Failed to parse $SYSTEMD_GETTY_AUTO environment variable, ignoring: %m");
        else if (r > 0) {
                r = parse_boolean(getty_auto);
                if (r < 0)
                        log_warning_errno(r, "Failed to parse $SYSTEMD_GETTY_AUTO value \"%s\", ignoring: %m", getty_auto);
                else
                        arg_enabled = r;
        }

        if (!arg_enabled) {
                log_debug("Disabled, exiting.");
                return 0;
        }

        if (detect_container() > 0)
                /* Add console shell and look at $container_ttys, but don't do add any
                 * further magic if we are in a container. */
                return run_container();

        /* Automatically add in a serial getty on all active kernel consoles */
        _cleanup_free_ char *active = NULL;
        (void) read_one_line_file("/sys/class/tty/console/active", &active);
        for (const char *p = active;;) {
               _cleanup_free_ char *tty = NULL;

                r = extract_first_word(&p, &tty, NULL, 0);
                if (r < 0)
                        return log_error_errno(r, "Failed to parse /sys/class/tty/console/active: %m");
                if (r == 0)
                        break;

                /* We assume that gettys on virtual terminals are started via manual configuration and do
                 * this magic only for non-VC terminals. */

                if (isempty(tty) || tty_is_vc(tty))
                        continue;

                if (verify_tty(tty) < 0)
                        continue;

                r = add_serial_getty(tty);
                if (r < 0)
                        return r;
        }

        /* Automatically add in a serial getty on the first virtualizer console */
        FOREACH_STRING(j,
                       "hvc0",
                       "xvc0",
                       "hvsi0",
                       "sclp_line0",
                       "ttysclp0",
                       "3270!tty1") {
                _cleanup_free_ char *p = NULL;

                p = path_join("/sys/class/tty", j);
                if (!p)
                        return -ENOMEM;
                if (access(p, F_OK) < 0)
                        continue;

                r = add_serial_getty(j);
                if (r < 0)
                        return r;
        }

        return 0;
}

DEFINE_MAIN_GENERATOR_FUNCTION(run);
Commit	Line	Data
	1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
	2
	3	#include <errno.h>
	4	#include <fcntl.h>
	5	#include <unistd.h>
	6
	7	#include "alloc-util.h"
	8	#include "errno-util.h"
	9	#include "fd-util.h"
	10	#include "fileio.h"
	11	#include "generator.h"
	12	#include "log.h"
	13	#include "mkdir-label.h"
	14	#include "parse-util.h"
	15	#include "path-util.h"
	16	#include "process-util.h"
	17	#include "proc-cmdline.h"
	18	#include "strv.h"
	19	#include "terminal-util.h"
	20	#include "unit-name.h"
	21	#include "virt.h"
	22
	23	static const char *arg_dest = NULL;
	24	static bool arg_enabled = true;
	25
	26	static int add_symlink(const char fservice, const char tservice) {
	27	char from, to;
	28	int r;
	29
	30	assert(fservice);
	31	assert(tservice);
	32
	33	from = strjoina(SYSTEM_DATA_UNIT_DIR "/", fservice);
	34	to = strjoina(arg_dest, "/getty.target.wants/", tservice);
	35
	36	(void) mkdir_parents_label(to, 0755);
	37
	38	r = symlink(from, to);
	39	if (r < 0) {
	40	/* In case console=hvc0 is passed this will very likely result in EEXIST */
	41	if (errno == EEXIST)
	42	return 0;
	43
	44	return log_error_errno(errno, "Failed to create symlink %s: %m", to);
	45	}
	46
	47	return 0;
	48	}
	49
	50	static int add_serial_getty(const char *tty) {
	51	_cleanup_free_ char *n = NULL;
	52	int r;
	53
	54	assert(tty);
	55
	56	log_debug("Automatically adding serial getty for /dev/%s.", tty);
	57
	58	r = unit_name_from_path_instance("serial-getty", tty, ".service", &n);
	59	if (r < 0)
	60	return log_error_errno(r, "Failed to generate service name: %m");
	61
	62	return add_symlink("serial-getty@.service", n);
	63	}
	64
	65	static int add_container_getty(const char *tty) {
	66	_cleanup_free_ char *n = NULL;
	67	int r;
	68
	69	assert(tty);
	70
	71	log_debug("Automatically adding container getty for /dev/pts/%s.", tty);
	72
	73	r = unit_name_from_path_instance("container-getty", tty, ".service", &n);
	74	if (r < 0)
	75	return log_error_errno(r, "Failed to generate service name: %m");
	76
	77	return add_symlink("container-getty@.service", n);
	78	}
	79
	80	static int verify_tty(const char *name) {
	81	_cleanup_close_ int fd = -EBADF;
	82	const char *p;
	83
	84	/* Some TTYs are weird and have been enumerated but don't work
	85	* when you try to use them, such as classic ttyS0 and
	86	* friends. Let's check that and open the device and run
	87	* isatty() on it. */
	88
	89	p = strjoina("/dev/", name);
	90
	91	/* O_NONBLOCK is essential here, to make sure we don't wait
	92	* for DCD */
	93	fd = open(p, O_RDWR\|O_NONBLOCK\|O_NOCTTY\|O_CLOEXEC\|O_NOFOLLOW);
	94	if (fd < 0)
	95	return -errno;
	96
	97	errno = 0;
	98	if (isatty(fd) <= 0)
	99	return errno_or_else(EIO);
	100
	101	return 0;
	102	}
	103
	104	static int run_container(void) {
	105	_cleanup_free_ char *container_ttys = NULL;
	106	int r;
	107
	108	log_debug("Automatically adding console shell.");
	109
	110	r = add_symlink("console-getty.service", "console-getty.service");
	111	if (r < 0)
	112	return r;
	113
	114	/* When $container_ttys is set for PID 1, spawn gettys on all ptys named therein.
	115	* Note that despite the variable name we only support ptys here. */
	116
	117	(void) getenv_for_pid(1, "container_ttys", &container_ttys);
	118
	119	for (const char *p = container_ttys;;) {
	120	_cleanup_free_ char *word = NULL;
	121
	122	r = extract_first_word(&p, &word, NULL, 0);
	123	if (r < 0)
	124	return log_error_errno(r, "Failed to parse $container_ttys: %m");
	125	if (r == 0)
	126	return 0;
	127
	128	const char *tty = word;
	129
	130	/* First strip off /dev/ if it is specified */
	131	tty = path_startswith(tty, "/dev/") ?: tty;
	132
	133	/* Then, make sure it's actually a pty */
	134	tty = path_startswith(tty, "pts/");
	135	if (!tty)
	136	continue;
	137
	138	r = add_container_getty(tty);
	139	if (r < 0)
	140	return r;
	141	}
	142	}
	143
	144	static int parse_proc_cmdline_item(const char key, const char value, void *data) {
	145	int r;
	146
	147	assert(key);
	148
	149	if (proc_cmdline_key_streq(key, "systemd.getty_auto")) {
	150	r = value ? parse_boolean(value) : 1;
	151	if (r < 0)
	152	log_warning_errno(r, "Failed to parse getty_auto switch \"%s\", ignoring: %m", value);
	153	else
	154	arg_enabled = r;
	155	}
	156
	157	return 0;
	158	}
	159
	160	static int run(const char dest, const char dest_early, const char *dest_late) {
	161	_cleanup_free_ char *getty_auto = NULL;
	162	int r;
	163
	164	assert_se(arg_dest = dest);
	165
	166	r = proc_cmdline_parse(parse_proc_cmdline_item, NULL, 0);
	167	if (r < 0)
	168	log_warning_errno(r, "Failed to parse kernel command line, ignoring: %m");
	169
	170	r = getenv_for_pid(1, "SYSTEMD_GETTY_AUTO", &getty_auto);
	171	if (r < 0)
	172	log_warning_errno(r, "Failed to parse $SYSTEMD_GETTY_AUTO environment variable, ignoring: %m");
	173	else if (r > 0) {
	174	r = parse_boolean(getty_auto);
	175	if (r < 0)
	176	log_warning_errno(r, "Failed to parse $SYSTEMD_GETTY_AUTO value \"%s\", ignoring: %m", getty_auto);
	177	else
	178	arg_enabled = r;
	179	}
	180
	181	if (!arg_enabled) {
	182	log_debug("Disabled, exiting.");
	183	return 0;
	184	}
	185
	186	if (detect_container() > 0)
	187	/* Add console shell and look at $container_ttys, but don't do add any
	188	* further magic if we are in a container. */
	189	return run_container();
	190
	191	/* Automatically add in a serial getty on all active kernel consoles */
	192	_cleanup_free_ char *active = NULL;
	193	(void) read_one_line_file("/sys/class/tty/console/active", &active);
	194	for (const char *p = active;;) {
	195	_cleanup_free_ char *tty = NULL;
	196
	197	r = extract_first_word(&p, &tty, NULL, 0);
	198	if (r < 0)
	199	return log_error_errno(r, "Failed to parse /sys/class/tty/console/active: %m");
	200	if (r == 0)
	201	break;
	202
	203	/* We assume that gettys on virtual terminals are started via manual configuration and do
	204	* this magic only for non-VC terminals. */
	205
	206	if (isempty(tty) \|\| tty_is_vc(tty))
	207	continue;
	208
	209	if (verify_tty(tty) < 0)
	210	continue;
	211
	212	r = add_serial_getty(tty);
	213	if (r < 0)
	214	return r;
	215	}
	216
	217	/* Automatically add in a serial getty on the first virtualizer console */
	218	FOREACH_STRING(j,
	219	"hvc0",
	220	"xvc0",
	221	"hvsi0",
	222	"sclp_line0",
	223	"ttysclp0",
	224	"3270!tty1") {
	225	_cleanup_free_ char *p = NULL;
	226
	227	p = path_join("/sys/class/tty", j);
	228	if (!p)
	229	return -ENOMEM;
	230	if (access(p, F_OK) < 0)
	231	continue;
	232
	233	r = add_serial_getty(j);
	234	if (r < 0)
	235	return r;
	236	}
	237
	238	return 0;
	239	}
	240
	241	DEFINE_MAIN_GENERATOR_FUNCTION(run);