[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 = newa(char, 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);
                }
        }
}

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;

        k = 0;
        if (sscanf(p, "(%" PRIu64 ".%" PRIu64 ":%" PRIu64 "):%n",
                   &seconds,
                   &msec,
                   &id,
                   &k) != 3 || k == 0)
                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 messages 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
6e9417f5	165	c = newa(char, strlen(prefix) + (e - *p) + 2);
875c2e22 LP	166
875c2e22 LP	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
090a20cf	316	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
1dab14ab	344	k = 0;
1fa2f38f	345	if (sscanf(p, "(%" PRIu64 ".%" PRIu64 ":%" PRIu64 "):%n",
875c2e22 LP	346	&seconds,
	347	&msec,
	348	&id,
1dab14ab	349	&k) != 3 \|\| k == 0)
875c2e22 LP	350	return;
	351
	352	p += k;
5034c7bc LP	353	p += strspn(p, WHITESPACE);
	354
	355	if (isempty(p))
	356	return;
875c2e22	357
14c1abcc	358	n_iov_allocated = N_IOVEC_META_FIELDS + 8;
875c2e22 LP	359	iov = new(struct iovec, n_iov_allocated);
	360	if (!iov) {
	361	log_oom();
	362	return;
	363	}
	364
e6a7ec4b	365	iov[n_iov++] = IOVEC_MAKE_STRING("_TRANSPORT=audit");
875c2e22 LP	366
	367	sprintf(source_time_field, "_SOURCE_REALTIME_TIMESTAMP=%" PRIu64,
	368	(usec_t) seconds * USEC_PER_SEC + (usec_t) msec * USEC_PER_MSEC);
e6a7ec4b	369	iov[n_iov++] = IOVEC_MAKE_STRING(source_time_field);
875c2e22 LP	370
875c2e22 LP	371	sprintf(type_field, "_AUDIT_TYPE=%i", type);
e6a7ec4b	372	iov[n_iov++] = IOVEC_MAKE_STRING(type_field);
875c2e22 LP	373
875c2e22 LP	374	sprintf(id_field, "_AUDIT_ID=%" PRIu64, id);
e6a7ec4b	375	iov[n_iov++] = IOVEC_MAKE_STRING(id_field);
875c2e22	376
d6f4302b	377	assert_cc(4 == LOG_FAC(LOG_AUTH));
e6a7ec4b LP	378	iov[n_iov++] = IOVEC_MAKE_STRING("SYSLOG_FACILITY=4");
e6a7ec4b LP	379	iov[n_iov++] = IOVEC_MAKE_STRING("SYSLOG_IDENTIFIER=audit");
cd556b6c	380
8bb3626d ZJS	381	type_name = audit_type_name_alloca(type);
8bb3626d ZJS	382
14c1abcc JR	383	type_field_name = strjoina("_AUDIT_TYPE_NAME=", type_name);
	384	iov[n_iov++] = IOVEC_MAKE_STRING(type_field_name);
	385
8bb3626d	386	m = strjoina("MESSAGE=", type_name, " ", p);
e6a7ec4b	387	iov[n_iov++] = IOVEC_MAKE_STRING(m);
875c2e22 LP	388
	389	z = n_iov;
	390
	391	map_all_fields(p, map_fields_kernel, "_AUDIT_FIELD_", true, &iov, &n_iov_allocated, &n_iov);
	392
	393	if (!GREEDY_REALLOC(iov, n_iov_allocated, n_iov + N_IOVEC_META_FIELDS)) {
	394	log_oom();
	395	goto finish;
	396	}
	397
22e3a02b	398	server_dispatch_message(s, iov, n_iov, n_iov_allocated, NULL, NULL, LOG_NOTICE, 0);
875c2e22 LP	399
	400	finish:
	401	/* free() all entries that map_all_fields() added. All others
	402	* are allocated on the stack or are constant. */
	403
	404	for (; z < n_iov; z++)
	405	free(iov[z].iov_base);
	406	}
	407
	408	void server_process_audit_message(
	409	Server *s,
	410	const void *buffer,
	411	size_t buffer_size,
	412	const struct ucred *ucred,
875c2e22 LP	413	const union sockaddr_union *sa,
	414	socklen_t salen) {
	415
	416	const struct nlmsghdr *nl = buffer;
	417
	418	assert(s);
	419
	420	if (buffer_size < ALIGN(sizeof(struct nlmsghdr)))
	421	return;
	422
	423	assert(buffer);
	424
	425	/* Filter out fake data */
	426	if (!sa \|\|
	427	salen != sizeof(struct sockaddr_nl) \|\|
	428	sa->nl.nl_family != AF_NETLINK \|\|
	429	sa->nl.nl_pid != 0) {
	430	log_debug("Audit netlink message from invalid sender.");
	431	return;
	432	}
	433
	434	if (!ucred \|\| ucred->pid != 0) {
	435	log_debug("Audit netlink message with invalid credentials.");
	436	return;
	437	}
	438
	439	if (!NLMSG_OK(nl, buffer_size)) {
	440	log_error("Audit netlink message truncated.");
	441	return;
	442	}
	443
	444	/* Ignore special Netlink messages */
	445	if (IN_SET(nl->nlmsg_type, NLMSG_NOOP, NLMSG_ERROR))
	446	return;
	447
5238e957	448	/* Except AUDIT_USER, all messages below AUDIT_FIRST_USER_MSG are control messages, let's ignore those */
ed563b60	449	if (nl->nlmsg_type < AUDIT_FIRST_USER_MSG && nl->nlmsg_type != AUDIT_USER)
875c2e22 LP	450	return;
875c2e22 LP	451
0b97208d	452	process_audit_string(s, nl->nlmsg_type, NLMSG_DATA(nl), nl->nlmsg_len - ALIGN(sizeof(struct nlmsghdr)));
875c2e22 LP	453	}
875c2e22 LP	454
4d9ced99 LP	455	static int enable_audit(int fd, bool b) {
	456	struct {
	457	union {
	458	struct nlmsghdr header;
	459	uint8_t header_space[NLMSG_HDRLEN];
	460	};
	461	struct audit_status body;
	462	} _packed_ request = {
	463	.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct audit_status)),
	464	.header.nlmsg_type = AUDIT_SET,
	465	.header.nlmsg_flags = NLM_F_REQUEST,
	466	.header.nlmsg_seq = 1,
	467	.header.nlmsg_pid = 0,
	468	.body.mask = AUDIT_STATUS_ENABLED,
	469	.body.enabled = b,
	470	};
	471	union sockaddr_union sa = {
	472	.nl.nl_family = AF_NETLINK,
	473	.nl.nl_pid = 0,
	474	};
	475	struct iovec iovec = {
	476	.iov_base = &request,
	477	.iov_len = NLMSG_LENGTH(sizeof(struct audit_status)),
	478	};
	479	struct msghdr mh = {
	480	.msg_iov = &iovec,
	481	.msg_iovlen = 1,
	482	.msg_name = &sa.sa,
	483	.msg_namelen = sizeof(sa.nl),
	484	};
	485
	486	ssize_t n;
	487
	488	n = sendmsg(fd, &mh, MSG_NOSIGNAL);
	489	if (n < 0)
	490	return -errno;
	491	if (n != NLMSG_LENGTH(sizeof(struct audit_status)))
	492	return -EIO;
	493
	494	/* We don't wait for the result here, we can't do anything
	495	* about it anyway */
	496
	497	return 0;
	498	}
	499
875c2e22	500	int server_open_audit(Server *s) {
875c2e22 LP	501	int r;
	502
	503	if (s->audit_fd < 0) {
	504	static const union sockaddr_union sa = {
	505	.nl.nl_family = AF_NETLINK,
	506	.nl.nl_pid = 0,
	507	.nl.nl_groups = AUDIT_NLGRP_READLOG,
	508	};
	509
	510	s->audit_fd = socket(AF_NETLINK, SOCK_RAW\|SOCK_CLOEXEC\|SOCK_NONBLOCK, NETLINK_AUDIT);
	511	if (s->audit_fd < 0) {
3742095b	512	if (IN_SET(errno, EAFNOSUPPORT, EPROTONOSUPPORT))
875c2e22 LP	513	log_debug("Audit not supported in the kernel.");
875c2e22 LP	514	else
56f64d95	515	log_warning_errno(errno, "Failed to create audit socket, ignoring: %m");
875c2e22 LP	516
	517	return 0;
	518	}
	519
417a7fdc LP	520	if (bind(s->audit_fd, &sa.sa, sizeof(sa.nl)) < 0) {
	521	log_warning_errno(errno,
	522	"Failed to join audit multicast group. "
	523	"The kernel is probably too old or multicast reading is not supported. "
	524	"Ignoring: %m");
	525	s->audit_fd = safe_close(s->audit_fd);
	526	return 0;
	527	}
875c2e22	528	} else
48440643	529	(void) fd_nonblock(s->audit_fd, true);
875c2e22	530
2ff48e98	531	r = setsockopt_int(s->audit_fd, SOL_SOCKET, SO_PASSCRED, true);
4a62c710	532	if (r < 0)
2ff48e98	533	return log_error_errno(r, "Failed to set SO_PASSCRED on audit socket: %m");
875c2e22	534
8531ae70	535	r = sd_event_add_io(s->event, &s->audit_event_source, s->audit_fd, EPOLLIN, server_process_datagram, s);
23bbb0de MS	536	if (r < 0)
23bbb0de MS	537	return log_error_errno(r, "Failed to add audit fd to event loop: %m");
875c2e22	538
4d9ced99 LP	539	/* We are listening now, try to enable audit */
	540	r = enable_audit(s->audit_fd, true);
	541	if (r < 0)
da927ba9	542	log_warning_errno(r, "Failed to issue audit enable call: %m");
4d9ced99	543
875c2e22 LP	544	return 0;
875c2e22 LP	545	}