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-rw-r--r--src/journal/journald-audit.c545
1 files changed, 545 insertions, 0 deletions
diff --git a/src/journal/journald-audit.c b/src/journal/journald-audit.c
new file mode 100644
index 0000000..accbad4
--- /dev/null
+++ b/src/journal/journald-audit.c
@@ -0,0 +1,545 @@
+/* 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 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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 18:54:11 +0000