#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, unsigned *n_iov);

} MapField;

static int map_simple_field(const char *field, const char **p, struct iovec **iov, size_t *n_iov_allocated, unsigned *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; *e != ' ' && *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].iov_base = c;

(*iov)[*n_iov].iov_len = l;

(*n_iov) ++;

*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, unsigned *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; *e != ' ' && *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].iov_base = c;

(*iov)[*n_iov].iov_len = l;

(*n_iov) ++;

*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, unsigned *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, unsigned *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, unsigned *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 (*e == 0 || *e == ' ')

return 0;

if (*e == '=')

break;

if (!((*e >= 'a' && *e <= 'z') ||

(*e >= 'A' && *e <= 'Z') ||

(*e >= '0' && *e <= '9') ||

*e == '_' || *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;

}

static const MapField map_fields_kernel[] = {

/* First, we map certain well-known audit fields into native

{ "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,

{ "path=", "_AUDIT_FIELD_PATH=", map_string_field },

{ "dev=", "_AUDIT_FIELD_DEV=", map_string_field },

{ "name=", "_AUDIT_FIELD_NAME=", map_string_field },

{}

};

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,

unsigned *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

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) {

_cleanup_free_ struct iovec *iov = NULL;

size_t n_iov_allocated = 0;

unsigned n_iov = 0, k;

uint64_t seconds, msec, id;

const char *p, *type_name;

unsigned z;

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;

assert(s);

if (size <= 0)

return;

if (!data)

return;

/* Note that the input buffer is NUL terminated, but let's

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 + 7;

iov = new(struct iovec, n_iov_allocated);

if (!iov) {

log_oom();

return;

}

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

sprintf(source_time_field, "_SOURCE_REALTIME_TIMESTAMP=%" PRIu64,

(usec_t) seconds * USEC_PER_SEC + (usec_t) msec * USEC_PER_MSEC);

IOVEC_SET_STRING(iov[n_iov++], source_time_field);

sprintf(type_field, "_AUDIT_TYPE=%i", type);

IOVEC_SET_STRING(iov[n_iov++], type_field);

sprintf(id_field, "_AUDIT_ID=%" PRIu64, id);

IOVEC_SET_STRING(iov[n_iov++], id_field);

assert_cc(4 == LOG_FAC(LOG_AUTH));

IOVEC_SET_STRING(iov[n_iov++], "SYSLOG_FACILITY=4");

IOVEC_SET_STRING(iov[n_iov++], "SYSLOG_IDENTIFIER=audit");

type_name = audit_type_name_alloca(type);

m = strjoina("MESSAGE=", type_name, " ", p);

IOVEC_SET_STRING(iov[n_iov++], 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, NULL, 0, NULL, LOG_NOTICE, 0);

finish:

/* free() all entries that map_all_fields() added. All others

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;

/* Below AUDIT_FIRST_USER_MSG theer are only control messages, let's ignore those */

if (nl->nlmsg_type < AUDIT_FIRST_USER_MSG)

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

return 0;

}

int server_open_audit(Server *s) {

static const int one = 1;

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 (errno == EAFNOSUPPORT || errno == 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

fd_nonblock(s->audit_fd, 1);

r = setsockopt(s->audit_fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one));

if (r < 0)

return log_error_errno(errno, "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;

}