[thirdparty/systemd.git] / src / journal / journald-audit.c

/* SPDX-License-Identifier: LGPL-2.1+ */

#include "alloc-util.h"
#include "audit-type.h"
#include "fd-util.h"
#include "hexdecoct.h"
#include "io-util.h"
#include "journald-audit.h"
#include "missing.h"
#include "string-util.h"

typedef struct MapField {
        const char *audit_field;
        const char *journal_field;
        int (*map)(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, size_t *n_iov);
} MapField;

static int map_simple_field(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, size_t *n_iov) {
        _cleanup_free_ char *c = NULL;
        size_t l = 0, allocated = 0;
        const char *e;

        assert(field);
        assert(p);
        assert(iov);
        assert(n_iov);

        l = strlen(field);
        allocated = l + 1;
        c = malloc(allocated);
        if (!c)
                return -ENOMEM;

        memcpy(c, field, l);
        for (e = *p; !IN_SET(*e, 0, ' '); e++) {
                if (!GREEDY_REALLOC(c, allocated, l+2))
                        return -ENOMEM;

                c[l++] = *e;
        }

        c[l] = 0;

        if (!GREEDY_REALLOC(*iov, *n_iov_allocated, *n_iov + 1))
                return -ENOMEM;

        (*iov)[(*n_iov)++] = IOVEC_MAKE(c, l);

        *p = e;
        c = NULL;

        return 1;
}

static int map_string_field_internal(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, size_t *n_iov, bool filter_printable) {
        _cleanup_free_ char *c = NULL;
        const char *s, *e;
        size_t l;

        assert(field);
        assert(p);
        assert(iov);
        assert(n_iov);

        /* The kernel formats string fields in one of two formats. */

        if (**p == '"') {
                /* Normal quoted syntax */
                s = *p + 1;
                e = strchr(s, '"');
                if (!e)
                        return 0;

                l = strlen(field) + (e - s);
                c = malloc(l+1);
                if (!c)
                        return -ENOMEM;

                *((char*) mempcpy(stpcpy(c, field), s, e - s)) = 0;

                e += 1;

        } else if (unhexchar(**p) >= 0) {
                /* Hexadecimal escaping */
                size_t allocated = 0;

                l = strlen(field);
                allocated = l + 2;
                c = malloc(allocated);
                if (!c)
                        return -ENOMEM;

                memcpy(c, field, l);
                for (e = *p; !IN_SET(*e, 0, ' '); e += 2) {
                        int a, b;
                        uint8_t x;

                        a = unhexchar(e[0]);
                        if (a < 0)
                                return 0;

                        b = unhexchar(e[1]);
                        if (b < 0)
                                return 0;

                        x = ((uint8_t) a << 4 | (uint8_t) b);

                        if (filter_printable && x < (uint8_t) ' ')
                                x = (uint8_t) ' ';

                        if (!GREEDY_REALLOC(c, allocated, l+2))
                                return -ENOMEM;

                        c[l++] = (char) x;
                }

                c[l] = 0;
        } else
                return 0;

        if (!GREEDY_REALLOC(*iov, *n_iov_allocated, *n_iov + 1))
                return -ENOMEM;

        (*iov)[(*n_iov)++] = IOVEC_MAKE(c, l);

        *p = e;
        c = NULL;

        return 1;
}

static int map_string_field(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, size_t *n_iov) {
        return map_string_field_internal(field, p, iov, n_iov_allocated, n_iov, false);
}

static int map_string_field_printable(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, size_t *n_iov) {
        return map_string_field_internal(field, p, iov, n_iov_allocated, n_iov, true);
}

static int map_generic_field(const char *prefix, const char **p, struct iovec **iov, size_t *n_iov_allocated, size_t *n_iov) {
        const char *e, *f;
        char *c, *t;
        int r;

        /* Implements fallback mappings for all fields we don't know */

        for (e = *p; e < *p + 16; e++) {

                if (IN_SET(*e, 0, ' '))
                        return 0;

                if (*e == '=')
                        break;

                if (!((*e >= 'a' && *e <= 'z') ||
                      (*e >= 'A' && *e <= 'Z') ||
                      (*e >= '0' && *e <= '9') ||
                      IN_SET(*e, '_', '-')))
                        return 0;
        }

        if (e <= *p || e >= *p + 16)
                return 0;

        c = alloca(strlen(prefix) + (e - *p) + 2);

        t = stpcpy(c, prefix);
        for (f = *p; f < e; f++) {
                char x;

                if (*f >= 'a' && *f <= 'z')
                        x = (*f - 'a') + 'A'; /* uppercase */
                else if (*f == '-')
                        x = '_'; /* dashes → underscores */
                else
                        x = *f;

                *(t++) = x;
        }
        strcpy(t, "=");

        e++;

        r = map_simple_field(c, &e, iov, n_iov_allocated, n_iov);
        if (r < 0)
                return r;

        *p = e;
        return r;
}

/* Kernel fields are those occurring in the audit string before
 * msg='. All of these fields are trusted, hence carry the "_" prefix.
 * We try to translate the fields we know into our native names. The
 * other's are generically mapped to _AUDIT_FIELD_XYZ= */
static const MapField map_fields_kernel[] = {

        /* First, we map certain well-known audit fields into native
         * well-known fields */
        { "pid=",       "_PID=",              map_simple_field },
        { "ppid=",      "_PPID=",             map_simple_field },
        { "uid=",       "_UID=",              map_simple_field },
        { "euid=",      "_EUID=",             map_simple_field },
        { "fsuid=",     "_FSUID=",            map_simple_field },
        { "gid=",       "_GID=",              map_simple_field },
        { "egid=",      "_EGID=",             map_simple_field },
        { "fsgid=",     "_FSGID=",            map_simple_field },
        { "tty=",       "_TTY=",              map_simple_field },
        { "ses=",       "_AUDIT_SESSION=",    map_simple_field },
        { "auid=",      "_AUDIT_LOGINUID=",   map_simple_field },
        { "subj=",      "_SELINUX_CONTEXT=",  map_simple_field },
        { "comm=",      "_COMM=",             map_string_field },
        { "exe=",       "_EXE=",              map_string_field },
        { "proctitle=", "_CMDLINE=",          map_string_field_printable },

        /* Some fields don't map to native well-known fields. However,
         * we know that they are string fields, hence let's undo
         * string field escaping for them, though we stick to the
         * generic field names. */
        { "path=",      "_AUDIT_FIELD_PATH=", map_string_field },
        { "dev=",       "_AUDIT_FIELD_DEV=",  map_string_field },
        { "name=",      "_AUDIT_FIELD_NAME=", map_string_field },
        {}
};

/* Userspace fields are those occurring in the audit string after
 * msg='. All of these fields are untrusted, hence carry no "_"
 * prefix. We map the fields we don't know to AUDIT_FIELD_XYZ= */
static const MapField map_fields_userspace[] = {
        { "cwd=",       "AUDIT_FIELD_CWD=",   map_string_field },
        { "cmd=",       "AUDIT_FIELD_CMD=",   map_string_field },
        { "acct=",      "AUDIT_FIELD_ACCT=",  map_string_field },
        { "exe=",       "AUDIT_FIELD_EXE=",   map_string_field },
        { "comm=",      "AUDIT_FIELD_COMM=",  map_string_field },
        {}
};

static int map_all_fields(
                const char *p,
                const MapField map_fields[],
                const char *prefix,
                bool handle_msg,
                struct iovec **iov,
                size_t *n_iov_allocated,
                size_t *n_iov) {

        int r;

        assert(p);
        assert(iov);
        assert(n_iov_allocated);
        assert(n_iov);

        for (;;) {
                bool mapped = false;
                const MapField *m;
                const char *v;

                p += strspn(p, WHITESPACE);

                if (*p == 0)
                        return 0;

                if (handle_msg) {
                        v = startswith(p, "msg='");
                        if (v) {
                                const char *e;
                                char *c;

                                /* Userspace message. It's enclosed in
                                   simple quotation marks, is not
                                   escaped, but the last field in the
                                   line, hence let's remove the
                                   quotation mark, and apply the
                                   userspace mapping instead of the
                                   kernel mapping. */

                                e = endswith(v, "'");
                                if (!e)
                                        return 0; /* don't continue splitting up if the final quotation mark is missing */

                                c = strndupa(v, e - v);
                                return map_all_fields(c, map_fields_userspace, "AUDIT_FIELD_", false, iov, n_iov_allocated, n_iov);
                        }
                }

                /* Try to map the kernel fields to our own names */
                for (m = map_fields; m->audit_field; m++) {
                        v = startswith(p, m->audit_field);
                        if (!v)
                                continue;

                        r = m->map(m->journal_field, &v, iov, n_iov_allocated, n_iov);
                        if (r < 0)
                                return log_debug_errno(r, "Failed to parse audit array: %m");

                        if (r > 0) {
                                mapped = true;
                                p = v;
                                break;
                        }
                }

                if (!mapped) {
                        r = map_generic_field(prefix, &p, iov, n_iov_allocated, n_iov);
                        if (r < 0)
                                return log_debug_errno(r, "Failed to parse audit array: %m");

                        if (r == 0)
                                /* Couldn't process as generic field, let's just skip over it */
                                p += strcspn(p, WHITESPACE);
                }
        }
}

static void process_audit_string(Server *s, int type, const char *data, size_t size) {
        size_t n_iov_allocated = 0, n_iov = 0, z;
        _cleanup_free_ struct iovec *iov = NULL;
        uint64_t seconds, msec, id;
        const char *p, *type_name;
        char id_field[sizeof("_AUDIT_ID=") + DECIMAL_STR_MAX(uint64_t)],
             type_field[sizeof("_AUDIT_TYPE=") + DECIMAL_STR_MAX(int)],
             source_time_field[sizeof("_SOURCE_REALTIME_TIMESTAMP=") + DECIMAL_STR_MAX(usec_t)];
        char *m, *type_field_name;
        int k;

        assert(s);

        if (size <= 0)
                return;

        if (!data)
                return;

        /* Note that the input buffer is NUL terminated, but let's
         * check whether there is a spurious NUL byte */
        if (memchr(data, 0, size))
                return;

        p = startswith(data, "audit");
        if (!p)
                return;

        if (sscanf(p, "(%" PRIu64 ".%" PRIu64 ":%" PRIu64 "):%n",
                   &seconds,
                   &msec,
                   &id,
                   &k) != 3)
                return;

        p += k;
        p += strspn(p, WHITESPACE);

        if (isempty(p))
                return;

        n_iov_allocated = N_IOVEC_META_FIELDS + 8;
        iov = new(struct iovec, n_iov_allocated);
        if (!iov) {
                log_oom();
                return;
        }

        iov[n_iov++] = IOVEC_MAKE_STRING("_TRANSPORT=audit");

        sprintf(source_time_field, "_SOURCE_REALTIME_TIMESTAMP=%" PRIu64,
                (usec_t) seconds * USEC_PER_SEC + (usec_t) msec * USEC_PER_MSEC);
        iov[n_iov++] = IOVEC_MAKE_STRING(source_time_field);

        sprintf(type_field, "_AUDIT_TYPE=%i", type);
        iov[n_iov++] = IOVEC_MAKE_STRING(type_field);

        sprintf(id_field, "_AUDIT_ID=%" PRIu64, id);
        iov[n_iov++] = IOVEC_MAKE_STRING(id_field);

        assert_cc(4 == LOG_FAC(LOG_AUTH));
        iov[n_iov++] = IOVEC_MAKE_STRING("SYSLOG_FACILITY=4");
        iov[n_iov++] = IOVEC_MAKE_STRING("SYSLOG_IDENTIFIER=audit");

        type_name = audit_type_name_alloca(type);

        type_field_name = strjoina("_AUDIT_TYPE_NAME=", type_name);
        iov[n_iov++] = IOVEC_MAKE_STRING(type_field_name);

        m = strjoina("MESSAGE=", type_name, " ", p);
        iov[n_iov++] = IOVEC_MAKE_STRING(m);

        z = n_iov;

        map_all_fields(p, map_fields_kernel, "_AUDIT_FIELD_", true, &iov, &n_iov_allocated, &n_iov);

        if (!GREEDY_REALLOC(iov, n_iov_allocated, n_iov + N_IOVEC_META_FIELDS)) {
                log_oom();
                goto finish;
        }

        server_dispatch_message(s, iov, n_iov, n_iov_allocated, NULL, NULL, LOG_NOTICE, 0);

finish:
        /* free() all entries that map_all_fields() added. All others
         * are allocated on the stack or are constant. */

        for (; z < n_iov; z++)
                free(iov[z].iov_base);
}

void server_process_audit_message(
                Server *s,
                const void *buffer,
                size_t buffer_size,
                const struct ucred *ucred,
                const union sockaddr_union *sa,
                socklen_t salen) {

        const struct nlmsghdr *nl = buffer;

        assert(s);

        if (buffer_size < ALIGN(sizeof(struct nlmsghdr)))
                return;

        assert(buffer);

        /* Filter out fake data */
        if (!sa ||
            salen != sizeof(struct sockaddr_nl) ||
            sa->nl.nl_family != AF_NETLINK ||
            sa->nl.nl_pid != 0) {
                log_debug("Audit netlink message from invalid sender.");
                return;
        }

        if (!ucred || ucred->pid != 0) {
                log_debug("Audit netlink message with invalid credentials.");
                return;
        }

        if (!NLMSG_OK(nl, buffer_size)) {
                log_error("Audit netlink message truncated.");
                return;
        }

        /* Ignore special Netlink messages */
        if (IN_SET(nl->nlmsg_type, NLMSG_NOOP, NLMSG_ERROR))
                return;

        /* Except AUDIT_USER, all messsages below AUDIT_FIRST_USER_MSG are control messages, let's ignore those */
        if (nl->nlmsg_type < AUDIT_FIRST_USER_MSG && nl->nlmsg_type != AUDIT_USER)
                return;

        process_audit_string(s, nl->nlmsg_type, NLMSG_DATA(nl), nl->nlmsg_len - ALIGN(sizeof(struct nlmsghdr)));
}

static int enable_audit(int fd, bool b) {
        struct {
                union {
                        struct nlmsghdr header;
                        uint8_t header_space[NLMSG_HDRLEN];
                };
                struct audit_status body;
        } _packed_ request = {
                .header.nlmsg_len = NLMSG_LENGTH(sizeof(struct audit_status)),
                .header.nlmsg_type = AUDIT_SET,
                .header.nlmsg_flags = NLM_F_REQUEST,
                .header.nlmsg_seq = 1,
                .header.nlmsg_pid = 0,
                .body.mask = AUDIT_STATUS_ENABLED,
                .body.enabled = b,
        };
        union sockaddr_union sa = {
                .nl.nl_family = AF_NETLINK,
                .nl.nl_pid = 0,
        };
        struct iovec iovec = {
                .iov_base = &request,
                .iov_len = NLMSG_LENGTH(sizeof(struct audit_status)),
        };
        struct msghdr mh = {
                .msg_iov = &iovec,
                .msg_iovlen = 1,
                .msg_name = &sa.sa,
                .msg_namelen = sizeof(sa.nl),
        };

        ssize_t n;

        n = sendmsg(fd, &mh, MSG_NOSIGNAL);
        if (n < 0)
                return -errno;
        if (n != NLMSG_LENGTH(sizeof(struct audit_status)))
                return -EIO;

        /* We don't wait for the result here, we can't do anything
         * about it anyway */

        return 0;
}

int server_open_audit(Server *s) {
        int r;

        if (s->audit_fd < 0) {
                static const union sockaddr_union sa = {
                        .nl.nl_family = AF_NETLINK,
                        .nl.nl_pid    = 0,
                        .nl.nl_groups = AUDIT_NLGRP_READLOG,
                };

                s->audit_fd = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_AUDIT);
                if (s->audit_fd < 0) {
                        if (IN_SET(errno, EAFNOSUPPORT, EPROTONOSUPPORT))
                                log_debug("Audit not supported in the kernel.");
                        else
                                log_warning_errno(errno, "Failed to create audit socket, ignoring: %m");

                        return 0;
                }

                if (bind(s->audit_fd, &sa.sa, sizeof(sa.nl)) < 0) {
                        log_warning_errno(errno,
                                          "Failed to join audit multicast group. "
                                          "The kernel is probably too old or multicast reading is not supported. "
                                          "Ignoring: %m");
                        s->audit_fd = safe_close(s->audit_fd);
                        return 0;
                }
        } else
                (void) fd_nonblock(s->audit_fd, true);

        r = setsockopt_int(s->audit_fd, SOL_SOCKET, SO_PASSCRED, true);
        if (r < 0)
                return log_error_errno(r, "Failed to set SO_PASSCRED on audit socket: %m");

        r = sd_event_add_io(s->event, &s->audit_event_source, s->audit_fd, EPOLLIN, server_process_datagram, s);
        if (r < 0)
                return log_error_errno(r, "Failed to add audit fd to event loop: %m");

        /* We are listening now, try to enable audit */
        r = enable_audit(s->audit_fd, true);
        if (r < 0)
                log_warning_errno(r, "Failed to issue audit enable call: %m");

        return 0;
}
Commit	Line	Data
53e1b683	1	/* SPDX-License-Identifier: LGPL-2.1+ */
875c2e22	2
b5efdb8a	3	#include "alloc-util.h"
07630cea	4	#include "audit-type.h"
3ffd4af2	5	#include "fd-util.h"
afc5dbf3 LP	6	#include "hexdecoct.h"
afc5dbf3 LP	7	#include "io-util.h"
3ffd4af2	8	#include "journald-audit.h"
875c2e22	9	#include "missing.h"
07630cea	10	#include "string-util.h"
875c2e22 LP	11
	12	typedef struct MapField {
	13	const char *audit_field;
	14	const char *journal_field;
d3070fbd	15	int (map)(const char field, const char p, struct iovec iov, size_t n_iov_allocated, size_t n_iov);
875c2e22 LP	16	} MapField;
875c2e22 LP	17
d3070fbd	18	static int map_simple_field(const char field, const char p, struct iovec iov, size_t n_iov_allocated, size_t *n_iov) {
875c2e22 LP	19	_cleanup_free_ char *c = NULL;
	20	size_t l = 0, allocated = 0;
	21	const char *e;
	22
	23	assert(field);
	24	assert(p);
	25	assert(iov);
	26	assert(n_iov);
	27
	28	l = strlen(field);
	29	allocated = l + 1;
	30	c = malloc(allocated);
	31	if (!c)
	32	return -ENOMEM;
	33
	34	memcpy(c, field, l);
4c701096	35	for (e = p; !IN_SET(e, 0, ' '); e++) {
875c2e22 LP	36	if (!GREEDY_REALLOC(c, allocated, l+2))
	37	return -ENOMEM;
	38
	39	c[l++] = *e;
	40	}
	41
	42	c[l] = 0;
	43
	44	if (!GREEDY_REALLOC(iov, n_iov_allocated, *n_iov + 1))
	45	return -ENOMEM;
	46
dde26374	47	(iov)[(n_iov)++] = IOVEC_MAKE(c, l);
875c2e22 LP	48
	49	*p = e;
	50	c = NULL;
	51
	52	return 1;
	53	}
	54
d3070fbd	55	static int map_string_field_internal(const char field, const char p, struct iovec iov, size_t n_iov_allocated, size_t *n_iov, bool filter_printable) {
875c2e22 LP	56	_cleanup_free_ char *c = NULL;
	57	const char s, e;
	58	size_t l;
	59
	60	assert(field);
	61	assert(p);
	62	assert(iov);
	63	assert(n_iov);
	64
	65	/* The kernel formats string fields in one of two formats. */
	66
	67	if (**p == '"') {
	68	/* Normal quoted syntax */
	69	s = *p + 1;
	70	e = strchr(s, '"');
	71	if (!e)
	72	return 0;
	73
	74	l = strlen(field) + (e - s);
	75	c = malloc(l+1);
	76	if (!c)
	77	return -ENOMEM;
	78
	79	((char) mempcpy(stpcpy(c, field), s, e - s)) = 0;
	80
	81	e += 1;
	82
	83	} else if (unhexchar(**p) >= 0) {
	84	/* Hexadecimal escaping */
	85	size_t allocated = 0;
	86
	87	l = strlen(field);
	88	allocated = l + 2;
	89	c = malloc(allocated);
	90	if (!c)
	91	return -ENOMEM;
	92
	93	memcpy(c, field, l);
4c701096	94	for (e = p; !IN_SET(e, 0, ' '); e += 2) {
875c2e22	95	int a, b;
78fe420f	96	uint8_t x;
875c2e22 LP	97
	98	a = unhexchar(e[0]);
	99	if (a < 0)
	100	return 0;
	101
	102	b = unhexchar(e[1]);
	103	if (b < 0)
	104	return 0;
	105
78fe420f LP	106	x = ((uint8_t) a << 4 \| (uint8_t) b);
	107
	108	if (filter_printable && x < (uint8_t) ' ')
	109	x = (uint8_t) ' ';
	110
875c2e22 LP	111	if (!GREEDY_REALLOC(c, allocated, l+2))
	112	return -ENOMEM;
	113
78fe420f	114	c[l++] = (char) x;
875c2e22 LP	115	}
	116
	117	c[l] = 0;
	118	} else
	119	return 0;
	120
	121	if (!GREEDY_REALLOC(iov, n_iov_allocated, *n_iov + 1))
	122	return -ENOMEM;
	123
dde26374	124	(iov)[(n_iov)++] = IOVEC_MAKE(c, l);
875c2e22 LP	125
	126	*p = e;
	127	c = NULL;
	128
	129	return 1;
	130	}
	131
d3070fbd	132	static int map_string_field(const char field, const char p, struct iovec iov, size_t n_iov_allocated, size_t *n_iov) {
78fe420f LP	133	return map_string_field_internal(field, p, iov, n_iov_allocated, n_iov, false);
	134	}
	135
d3070fbd	136	static int map_string_field_printable(const char field, const char p, struct iovec iov, size_t n_iov_allocated, size_t *n_iov) {
78fe420f LP	137	return map_string_field_internal(field, p, iov, n_iov_allocated, n_iov, true);
	138	}
	139
d3070fbd	140	static int map_generic_field(const char prefix, const char p, struct iovec iov, size_t n_iov_allocated, size_t *n_iov) {
875c2e22 LP	141	const char e, f;
	142	char c, t;
	143	int r;
	144
	145	/* Implements fallback mappings for all fields we don't know */
	146
	147	for (e = p; e < p + 16; e++) {
	148
4c701096	149	if (IN_SET(*e, 0, ' '))
875c2e22 LP	150	return 0;
	151
	152	if (*e == '=')
	153	break;
	154
	155	if (!((e >= 'a' && e <= 'z') \|\|
	156	(e >= 'A' && e <= 'Z') \|\|
	157	(e >= '0' && e <= '9') \|\|
4c701096	158	IN_SET(*e, '_', '-')))
875c2e22 LP	159	return 0;
	160	}
	161
	162	if (e <= p \|\| e >= p + 16)
	163	return 0;
	164
	165	c = alloca(strlen(prefix) + (e - *p) + 2);
	166
	167	t = stpcpy(c, prefix);
9833a66c LP	168	for (f = *p; f < e; f++) {
	169	char x;
	170
	171	if (f >= 'a' && f <= 'z')
	172	x = (f - 'a') + 'A'; / uppercase */
	173	else if (*f == '-')
	174	x = '_'; /* dashes → underscores */
	175	else
	176	x = *f;
	177
	178	*(t++) = x;
	179	}
875c2e22 LP	180	strcpy(t, "=");
875c2e22 LP	181
313cefa1	182	e++;
875c2e22 LP	183
	184	r = map_simple_field(c, &e, iov, n_iov_allocated, n_iov);
	185	if (r < 0)
	186	return r;
	187
	188	*p = e;
	189	return r;
	190	}
	191
f131770b	192	/* Kernel fields are those occurring in the audit string before
875c2e22 LP	193	* msg='. All of these fields are trusted, hence carry the "_" prefix.
	194	* We try to translate the fields we know into our native names. The
	195	* other's are generically mapped to _AUDIT_FIELD_XYZ= */
	196	static const MapField map_fields_kernel[] = {
	197
	198	/* First, we map certain well-known audit fields into native
	199	* well-known fields */
500cbc4e LP	200	{ "pid=", "_PID=", map_simple_field },
	201	{ "ppid=", "_PPID=", map_simple_field },
	202	{ "uid=", "_UID=", map_simple_field },
	203	{ "euid=", "_EUID=", map_simple_field },
	204	{ "fsuid=", "_FSUID=", map_simple_field },
	205	{ "gid=", "_GID=", map_simple_field },
	206	{ "egid=", "_EGID=", map_simple_field },
	207	{ "fsgid=", "_FSGID=", map_simple_field },
	208	{ "tty=", "_TTY=", map_simple_field },
	209	{ "ses=", "_AUDIT_SESSION=", map_simple_field },
	210	{ "auid=", "_AUDIT_LOGINUID=", map_simple_field },
	211	{ "subj=", "_SELINUX_CONTEXT=", map_simple_field },
	212	{ "comm=", "_COMM=", map_string_field },
	213	{ "exe=", "_EXE=", map_string_field },
	214	{ "proctitle=", "_CMDLINE=", map_string_field_printable },
875c2e22 LP	215
	216	/* Some fields don't map to native well-known fields. However,
	217	* we know that they are string fields, hence let's undo
	218	* string field escaping for them, though we stick to the
	219	* generic field names. */
500cbc4e LP	220	{ "path=", "_AUDIT_FIELD_PATH=", map_string_field },
	221	{ "dev=", "_AUDIT_FIELD_DEV=", map_string_field },
	222	{ "name=", "_AUDIT_FIELD_NAME=", map_string_field },
875c2e22 LP	223	{}
	224	};
	225
f131770b	226	/* Userspace fields are those occurring in the audit string after
875c2e22 LP	227	* msg='. All of these fields are untrusted, hence carry no "_"
	228	* prefix. We map the fields we don't know to AUDIT_FIELD_XYZ= */
	229	static const MapField map_fields_userspace[] = {
500cbc4e LP	230	{ "cwd=", "AUDIT_FIELD_CWD=", map_string_field },
	231	{ "cmd=", "AUDIT_FIELD_CMD=", map_string_field },
	232	{ "acct=", "AUDIT_FIELD_ACCT=", map_string_field },
	233	{ "exe=", "AUDIT_FIELD_EXE=", map_string_field },
	234	{ "comm=", "AUDIT_FIELD_COMM=", map_string_field },
875c2e22 LP	235	{}
	236	};
	237
	238	static int map_all_fields(
	239	const char *p,
	240	const MapField map_fields[],
	241	const char *prefix,
	242	bool handle_msg,
	243	struct iovec **iov,
	244	size_t *n_iov_allocated,
d3070fbd	245	size_t *n_iov) {
875c2e22 LP	246
	247	int r;
	248
	249	assert(p);
	250	assert(iov);
	251	assert(n_iov_allocated);
	252	assert(n_iov);
	253
	254	for (;;) {
	255	bool mapped = false;
	256	const MapField *m;
	257	const char *v;
	258
	259	p += strspn(p, WHITESPACE);
	260
	261	if (*p == 0)
	262	return 0;
	263
	264	if (handle_msg) {
	265	v = startswith(p, "msg='");
	266	if (v) {
	267	const char *e;
	268	char *c;
	269
	270	/* Userspace message. It's enclosed in
	271	simple quotation marks, is not
	272	escaped, but the last field in the
	273	line, hence let's remove the
	274	quotation mark, and apply the
	275	userspace mapping instead of the
	276	kernel mapping. */
	277
	278	e = endswith(v, "'");
	279	if (!e)
	280	return 0; /* don't continue splitting up if the final quotation mark is missing */
	281
	282	c = strndupa(v, e - v);
	283	return map_all_fields(c, map_fields_userspace, "AUDIT_FIELD_", false, iov, n_iov_allocated, n_iov);
	284	}
	285	}
	286
	287	/* Try to map the kernel fields to our own names */
	288	for (m = map_fields; m->audit_field; m++) {
	289	v = startswith(p, m->audit_field);
	290	if (!v)
	291	continue;
	292
	293	r = m->map(m->journal_field, &v, iov, n_iov_allocated, n_iov);
23bbb0de MS	294	if (r < 0)
23bbb0de MS	295	return log_debug_errno(r, "Failed to parse audit array: %m");
875c2e22 LP	296
	297	if (r > 0) {
	298	mapped = true;
	299	p = v;
	300	break;
	301	}
	302	}
	303
	304	if (!mapped) {
	305	r = map_generic_field(prefix, &p, iov, n_iov_allocated, n_iov);
23bbb0de MS	306	if (r < 0)
23bbb0de MS	307	return log_debug_errno(r, "Failed to parse audit array: %m");
875c2e22	308
ece174c5	309	if (r == 0)
875c2e22 LP	310	/* Couldn't process as generic field, let's just skip over it */
875c2e22 LP	311	p += strcspn(p, WHITESPACE);
875c2e22 LP	312	}
	313	}
	314	}
	315
0b97208d	316	static void process_audit_string(Server s, int type, const char data, size_t size) {
d3070fbd	317	size_t n_iov_allocated = 0, n_iov = 0, z;
875c2e22	318	_cleanup_free_ struct iovec *iov = NULL;
875c2e22	319	uint64_t seconds, msec, id;
8bb3626d	320	const char p, type_name;
875c2e22 LP	321	char id_field[sizeof("_AUDIT_ID=") + DECIMAL_STR_MAX(uint64_t)],
	322	type_field[sizeof("_AUDIT_TYPE=") + DECIMAL_STR_MAX(int)],
	323	source_time_field[sizeof("_SOURCE_REALTIME_TIMESTAMP=") + DECIMAL_STR_MAX(usec_t)];
14c1abcc	324	char m, type_field_name;
d3070fbd	325	int k;
875c2e22 LP	326
	327	assert(s);
	328
	329	if (size <= 0)
	330	return;
	331
	332	if (!data)
	333	return;
	334
	335	/* Note that the input buffer is NUL terminated, but let's
	336	* check whether there is a spurious NUL byte */
	337	if (memchr(data, 0, size))
	338	return;
	339
	340	p = startswith(data, "audit");
	341	if (!p)
	342	return;
	343
1fa2f38f	344	if (sscanf(p, "(%" PRIu64 ".%" PRIu64 ":%" PRIu64 "):%n",
875c2e22 LP	345	&seconds,
	346	&msec,
	347	&id,
	348	&k) != 3)
	349	return;
	350
	351	p += k;
5034c7bc LP	352	p += strspn(p, WHITESPACE);
	353
	354	if (isempty(p))
	355	return;
875c2e22	356
14c1abcc	357	n_iov_allocated = N_IOVEC_META_FIELDS + 8;
875c2e22 LP	358	iov = new(struct iovec, n_iov_allocated);
	359	if (!iov) {
	360	log_oom();
	361	return;
	362	}
	363
e6a7ec4b	364	iov[n_iov++] = IOVEC_MAKE_STRING("_TRANSPORT=audit");
875c2e22 LP	365
	366	sprintf(source_time_field, "_SOURCE_REALTIME_TIMESTAMP=%" PRIu64,
	367	(usec_t) seconds * USEC_PER_SEC + (usec_t) msec * USEC_PER_MSEC);
e6a7ec4b	368	iov[n_iov++] = IOVEC_MAKE_STRING(source_time_field);
875c2e22 LP	369
875c2e22 LP	370	sprintf(type_field, "_AUDIT_TYPE=%i", type);
e6a7ec4b	371	iov[n_iov++] = IOVEC_MAKE_STRING(type_field);
875c2e22 LP	372
875c2e22 LP	373	sprintf(id_field, "_AUDIT_ID=%" PRIu64, id);
e6a7ec4b	374	iov[n_iov++] = IOVEC_MAKE_STRING(id_field);
875c2e22	375
d6f4302b	376	assert_cc(4 == LOG_FAC(LOG_AUTH));
e6a7ec4b LP	377	iov[n_iov++] = IOVEC_MAKE_STRING("SYSLOG_FACILITY=4");
e6a7ec4b LP	378	iov[n_iov++] = IOVEC_MAKE_STRING("SYSLOG_IDENTIFIER=audit");
cd556b6c	379
8bb3626d ZJS	380	type_name = audit_type_name_alloca(type);
8bb3626d ZJS	381
14c1abcc JR	382	type_field_name = strjoina("_AUDIT_TYPE_NAME=", type_name);
	383	iov[n_iov++] = IOVEC_MAKE_STRING(type_field_name);
	384
8bb3626d	385	m = strjoina("MESSAGE=", type_name, " ", p);
e6a7ec4b	386	iov[n_iov++] = IOVEC_MAKE_STRING(m);
875c2e22 LP	387
	388	z = n_iov;
	389
	390	map_all_fields(p, map_fields_kernel, "_AUDIT_FIELD_", true, &iov, &n_iov_allocated, &n_iov);
	391
	392	if (!GREEDY_REALLOC(iov, n_iov_allocated, n_iov + N_IOVEC_META_FIELDS)) {
	393	log_oom();
	394	goto finish;
	395	}
	396
22e3a02b	397	server_dispatch_message(s, iov, n_iov, n_iov_allocated, NULL, NULL, LOG_NOTICE, 0);
875c2e22 LP	398
	399	finish:
	400	/* free() all entries that map_all_fields() added. All others
	401	* are allocated on the stack or are constant. */
	402
	403	for (; z < n_iov; z++)
	404	free(iov[z].iov_base);
	405	}
	406
	407	void server_process_audit_message(
	408	Server *s,
	409	const void *buffer,
	410	size_t buffer_size,
	411	const struct ucred *ucred,
875c2e22 LP	412	const union sockaddr_union *sa,
	413	socklen_t salen) {
	414
	415	const struct nlmsghdr *nl = buffer;
	416
	417	assert(s);
	418
	419	if (buffer_size < ALIGN(sizeof(struct nlmsghdr)))
	420	return;
	421
	422	assert(buffer);
	423
	424	/* Filter out fake data */
	425	if (!sa \|\|
	426	salen != sizeof(struct sockaddr_nl) \|\|
	427	sa->nl.nl_family != AF_NETLINK \|\|
	428	sa->nl.nl_pid != 0) {
	429	log_debug("Audit netlink message from invalid sender.");
	430	return;
	431	}
	432
	433	if (!ucred \|\| ucred->pid != 0) {
	434	log_debug("Audit netlink message with invalid credentials.");
	435	return;
	436	}
	437
	438	if (!NLMSG_OK(nl, buffer_size)) {
	439	log_error("Audit netlink message truncated.");
	440	return;
	441	}
	442
	443	/* Ignore special Netlink messages */
	444	if (IN_SET(nl->nlmsg_type, NLMSG_NOOP, NLMSG_ERROR))
	445	return;
	446
ed563b60 JR	447	/* Except AUDIT_USER, all messsages below AUDIT_FIRST_USER_MSG are control messages, let's ignore those */
ed563b60 JR	448	if (nl->nlmsg_type < AUDIT_FIRST_USER_MSG && nl->nlmsg_type != AUDIT_USER)
875c2e22 LP	449	return;
875c2e22 LP	450
0b97208d	451	process_audit_string(s, nl->nlmsg_type, NLMSG_DATA(nl), nl->nlmsg_len - ALIGN(sizeof(struct nlmsghdr)));
875c2e22 LP	452	}
875c2e22 LP	453
4d9ced99 LP	454	static int enable_audit(int fd, bool b) {
	455	struct {
	456	union {
	457	struct nlmsghdr header;
	458	uint8_t header_space[NLMSG_HDRLEN];
	459	};
	460	struct audit_status body;
	461	} _packed_ request = {
	462	.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct audit_status)),
	463	.header.nlmsg_type = AUDIT_SET,
	464	.header.nlmsg_flags = NLM_F_REQUEST,
	465	.header.nlmsg_seq = 1,
	466	.header.nlmsg_pid = 0,
	467	.body.mask = AUDIT_STATUS_ENABLED,
	468	.body.enabled = b,
	469	};
	470	union sockaddr_union sa = {
	471	.nl.nl_family = AF_NETLINK,
	472	.nl.nl_pid = 0,
	473	};
	474	struct iovec iovec = {
	475	.iov_base = &request,
	476	.iov_len = NLMSG_LENGTH(sizeof(struct audit_status)),
	477	};
	478	struct msghdr mh = {
	479	.msg_iov = &iovec,
	480	.msg_iovlen = 1,
	481	.msg_name = &sa.sa,
	482	.msg_namelen = sizeof(sa.nl),
	483	};
	484
	485	ssize_t n;
	486
	487	n = sendmsg(fd, &mh, MSG_NOSIGNAL);
	488	if (n < 0)
	489	return -errno;
	490	if (n != NLMSG_LENGTH(sizeof(struct audit_status)))
	491	return -EIO;
	492
	493	/* We don't wait for the result here, we can't do anything
	494	* about it anyway */
	495
	496	return 0;
	497	}
	498
875c2e22	499	int server_open_audit(Server *s) {
875c2e22 LP	500	int r;
	501
	502	if (s->audit_fd < 0) {
	503	static const union sockaddr_union sa = {
	504	.nl.nl_family = AF_NETLINK,
	505	.nl.nl_pid = 0,
	506	.nl.nl_groups = AUDIT_NLGRP_READLOG,
	507	};
	508
	509	s->audit_fd = socket(AF_NETLINK, SOCK_RAW\|SOCK_CLOEXEC\|SOCK_NONBLOCK, NETLINK_AUDIT);
	510	if (s->audit_fd < 0) {
3742095b	511	if (IN_SET(errno, EAFNOSUPPORT, EPROTONOSUPPORT))
875c2e22 LP	512	log_debug("Audit not supported in the kernel.");
875c2e22 LP	513	else
56f64d95	514	log_warning_errno(errno, "Failed to create audit socket, ignoring: %m");
875c2e22 LP	515
	516	return 0;
	517	}
	518
417a7fdc LP	519	if (bind(s->audit_fd, &sa.sa, sizeof(sa.nl)) < 0) {
	520	log_warning_errno(errno,
	521	"Failed to join audit multicast group. "
	522	"The kernel is probably too old or multicast reading is not supported. "
	523	"Ignoring: %m");
	524	s->audit_fd = safe_close(s->audit_fd);
	525	return 0;
	526	}
875c2e22	527	} else
48440643	528	(void) fd_nonblock(s->audit_fd, true);
875c2e22	529
2ff48e98	530	r = setsockopt_int(s->audit_fd, SOL_SOCKET, SO_PASSCRED, true);
4a62c710	531	if (r < 0)
2ff48e98	532	return log_error_errno(r, "Failed to set SO_PASSCRED on audit socket: %m");
875c2e22	533
8531ae70	534	r = sd_event_add_io(s->event, &s->audit_event_source, s->audit_fd, EPOLLIN, server_process_datagram, s);
23bbb0de MS	535	if (r < 0)
23bbb0de MS	536	return log_error_errno(r, "Failed to add audit fd to event loop: %m");
875c2e22	537
4d9ced99 LP	538	/* We are listening now, try to enable audit */
	539	r = enable_audit(s->audit_fd, true);
	540	if (r < 0)
da927ba9	541	log_warning_errno(r, "Failed to issue audit enable call: %m");
4d9ced99	542
875c2e22 LP	543	return 0;
875c2e22 LP	544	}