summaryrefslogtreecommitdiffstats
path: root/src/journal/journald-kmsg.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/journal/journald-kmsg.c')
-rw-r--r--src/journal/journald-kmsg.c467
1 files changed, 467 insertions, 0 deletions
diff --git a/src/journal/journald-kmsg.c b/src/journal/journald-kmsg.c
new file mode 100644
index 0000000..8ae7a23
--- /dev/null
+++ b/src/journal/journald-kmsg.c
@@ -0,0 +1,467 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <fcntl.h>
+#include <sys/epoll.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include "sd-device.h"
+#include "sd-messages.h"
+
+#include "alloc-util.h"
+#include "device-util.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "format-util.h"
+#include "fs-util.h"
+#include "io-util.h"
+#include "journald-kmsg.h"
+#include "journald-server.h"
+#include "journald-syslog.h"
+#include "log.h"
+#include "parse-util.h"
+#include "process-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+
+void server_forward_kmsg(
+ Server *s,
+ int priority,
+ const char *identifier,
+ const char *message,
+ const struct ucred *ucred) {
+
+ _cleanup_free_ char *ident_buf = NULL;
+ struct iovec iovec[5];
+ char header_priority[DECIMAL_STR_MAX(priority) + 3],
+ header_pid[STRLEN("[]: ") + DECIMAL_STR_MAX(pid_t) + 1];
+ int n = 0;
+
+ assert(s);
+ assert(priority >= 0);
+ assert(priority <= 999);
+ assert(message);
+
+ if (_unlikely_(LOG_PRI(priority) > s->max_level_kmsg))
+ return;
+
+ if (_unlikely_(s->dev_kmsg_fd < 0))
+ return;
+
+ /* Never allow messages with kernel facility to be written to
+ * kmsg, regardless where the data comes from. */
+ priority = syslog_fixup_facility(priority);
+
+ /* First: priority field */
+ xsprintf(header_priority, "<%i>", priority);
+ iovec[n++] = IOVEC_MAKE_STRING(header_priority);
+
+ /* Second: identifier and PID */
+ if (ucred) {
+ if (!identifier) {
+ (void) get_process_comm(ucred->pid, &ident_buf);
+ identifier = ident_buf;
+ }
+
+ xsprintf(header_pid, "["PID_FMT"]: ", ucred->pid);
+
+ if (identifier)
+ iovec[n++] = IOVEC_MAKE_STRING(identifier);
+
+ iovec[n++] = IOVEC_MAKE_STRING(header_pid);
+ } else if (identifier) {
+ iovec[n++] = IOVEC_MAKE_STRING(identifier);
+ iovec[n++] = IOVEC_MAKE_STRING(": ");
+ }
+
+ /* Fourth: message */
+ iovec[n++] = IOVEC_MAKE_STRING(message);
+ iovec[n++] = IOVEC_MAKE_STRING("\n");
+
+ if (writev(s->dev_kmsg_fd, iovec, n) < 0)
+ log_debug_errno(errno, "Failed to write to /dev/kmsg for logging: %m");
+}
+
+static bool is_us(const char *identifier, const char *pid) {
+ pid_t pid_num;
+
+ if (!identifier || !pid)
+ return false;
+
+ if (parse_pid(pid, &pid_num) < 0)
+ return false;
+
+ return pid_num == getpid_cached() &&
+ streq(identifier, program_invocation_short_name);
+}
+
+void dev_kmsg_record(Server *s, char *p, size_t l) {
+
+ _cleanup_free_ char *message = NULL, *syslog_priority = NULL, *syslog_pid = NULL, *syslog_facility = NULL, *syslog_identifier = NULL, *source_time = NULL, *identifier = NULL, *pid = NULL;
+ struct iovec iovec[N_IOVEC_META_FIELDS + 7 + N_IOVEC_KERNEL_FIELDS + 2 + N_IOVEC_UDEV_FIELDS];
+ char *kernel_device = NULL;
+ unsigned long long usec;
+ size_t n = 0, z = 0, j;
+ int priority, r;
+ char *e, *f, *k;
+ uint64_t serial;
+ size_t pl;
+ int saved_log_max_level = INT_MAX;
+ ClientContext *c = NULL;
+
+ assert(s);
+ assert(p);
+
+ if (l <= 0)
+ return;
+
+ e = memchr(p, ',', l);
+ if (!e)
+ return;
+ *e = 0;
+
+ r = safe_atoi(p, &priority);
+ if (r < 0 || priority < 0 || priority > 999)
+ return;
+
+ if (s->forward_to_kmsg && LOG_FAC(priority) != LOG_KERN)
+ return;
+
+ l -= (e - p) + 1;
+ p = e + 1;
+ e = memchr(p, ',', l);
+ if (!e)
+ return;
+ *e = 0;
+
+ r = safe_atou64(p, &serial);
+ if (r < 0)
+ return;
+
+ if (s->kernel_seqnum) {
+ /* We already read this one? */
+ if (serial < *s->kernel_seqnum)
+ return;
+
+ /* Did we lose any? */
+ if (serial > *s->kernel_seqnum)
+ server_driver_message(s, 0,
+ "MESSAGE_ID=" SD_MESSAGE_JOURNAL_MISSED_STR,
+ LOG_MESSAGE("Missed %"PRIu64" kernel messages",
+ serial - *s->kernel_seqnum),
+ NULL);
+
+ /* Make sure we never read this one again. Note that
+ * we always store the next message serial we expect
+ * here, simply because this makes handling the first
+ * message with serial 0 easy. */
+ *s->kernel_seqnum = serial + 1;
+ }
+
+ l -= (e - p) + 1;
+ p = e + 1;
+ f = memchr(p, ';', l);
+ if (!f)
+ return;
+ /* Kernel 3.6 has the flags field, kernel 3.5 lacks that */
+ e = memchr(p, ',', l);
+ if (!e || f < e)
+ e = f;
+ *e = 0;
+
+ r = safe_atollu(p, &usec);
+ if (r < 0)
+ return;
+
+ l -= (f - p) + 1;
+ p = f + 1;
+ e = memchr(p, '\n', l);
+ if (!e)
+ return;
+ *e = 0;
+
+ pl = e - p;
+ l -= (e - p) + 1;
+ k = e + 1;
+
+ for (j = 0; l > 0 && j < N_IOVEC_KERNEL_FIELDS; j++) {
+ char *m;
+ /* Metadata fields attached */
+
+ if (*k != ' ')
+ break;
+
+ k++, l--;
+
+ e = memchr(k, '\n', l);
+ if (!e)
+ goto finish;
+
+ *e = 0;
+
+ if (cunescape_length_with_prefix(k, e - k, "_KERNEL_", UNESCAPE_RELAX, &m) < 0)
+ break;
+
+ if (startswith(m, "_KERNEL_DEVICE="))
+ kernel_device = m + 15;
+
+ iovec[n++] = IOVEC_MAKE_STRING(m);
+ z++;
+
+ l -= (e - k) + 1;
+ k = e + 1;
+ }
+
+ if (kernel_device) {
+ _cleanup_(sd_device_unrefp) sd_device *d = NULL;
+
+ if (sd_device_new_from_device_id(&d, kernel_device) >= 0) {
+ const char *g;
+ char *b;
+
+ if (sd_device_get_devname(d, &g) >= 0) {
+ b = strjoin("_UDEV_DEVNODE=", g);
+ if (b) {
+ iovec[n++] = IOVEC_MAKE_STRING(b);
+ z++;
+ }
+ }
+
+ if (sd_device_get_sysname(d, &g) >= 0) {
+ b = strjoin("_UDEV_SYSNAME=", g);
+ if (b) {
+ iovec[n++] = IOVEC_MAKE_STRING(b);
+ z++;
+ }
+ }
+
+ j = 0;
+ FOREACH_DEVICE_DEVLINK(d, g) {
+
+ if (j >= N_IOVEC_UDEV_FIELDS)
+ break;
+
+ b = strjoin("_UDEV_DEVLINK=", g);
+ if (b) {
+ iovec[n++] = IOVEC_MAKE_STRING(b);
+ z++;
+ }
+
+ j++;
+ }
+ }
+ }
+
+ if (asprintf(&source_time, "_SOURCE_MONOTONIC_TIMESTAMP=%llu", usec) >= 0)
+ iovec[n++] = IOVEC_MAKE_STRING(source_time);
+
+ iovec[n++] = IOVEC_MAKE_STRING("_TRANSPORT=kernel");
+
+ if (asprintf(&syslog_priority, "PRIORITY=%i", priority & LOG_PRIMASK) >= 0)
+ iovec[n++] = IOVEC_MAKE_STRING(syslog_priority);
+
+ if (asprintf(&syslog_facility, "SYSLOG_FACILITY=%i", LOG_FAC(priority)) >= 0)
+ iovec[n++] = IOVEC_MAKE_STRING(syslog_facility);
+
+ if (LOG_FAC(priority) == LOG_KERN)
+ iovec[n++] = IOVEC_MAKE_STRING("SYSLOG_IDENTIFIER=kernel");
+ else {
+ pl -= syslog_parse_identifier((const char**) &p, &identifier, &pid);
+
+ /* Avoid logging any new messages when we're processing messages generated by ourselves via
+ * log_info() and friends to avoid infinite loops. */
+ if (is_us(identifier, pid)) {
+ if (!ratelimit_below(&s->kmsg_own_ratelimit))
+ return;
+
+ saved_log_max_level = log_get_max_level();
+ c = s->my_context;
+ log_set_max_level(LOG_NULL);
+ }
+
+ if (identifier) {
+ syslog_identifier = strjoin("SYSLOG_IDENTIFIER=", identifier);
+ if (syslog_identifier)
+ iovec[n++] = IOVEC_MAKE_STRING(syslog_identifier);
+ }
+
+ if (pid) {
+ syslog_pid = strjoin("SYSLOG_PID=", pid);
+ if (syslog_pid)
+ iovec[n++] = IOVEC_MAKE_STRING(syslog_pid);
+ }
+ }
+
+ if (cunescape_length_with_prefix(p, pl, "MESSAGE=", UNESCAPE_RELAX, &message) >= 0)
+ iovec[n++] = IOVEC_MAKE_STRING(message);
+
+
+ server_dispatch_message(s, iovec, n, ELEMENTSOF(iovec), c, NULL, priority, 0);
+
+ if (saved_log_max_level != INT_MAX)
+ log_set_max_level(saved_log_max_level);
+
+finish:
+ for (j = 0; j < z; j++)
+ free(iovec[j].iov_base);
+}
+
+static int server_read_dev_kmsg(Server *s) {
+ char buffer[8192+1]; /* the kernel-side limit per record is 8K currently */
+ ssize_t l;
+
+ assert(s);
+ assert(s->dev_kmsg_fd >= 0);
+
+ l = read(s->dev_kmsg_fd, buffer, sizeof(buffer) - 1);
+ if (l == 0)
+ return 0;
+ if (l < 0) {
+ /* Old kernels who don't allow reading from /dev/kmsg
+ * return EINVAL when we try. So handle this cleanly,
+ * but don' try to ever read from it again. */
+ if (errno == EINVAL) {
+ s->dev_kmsg_event_source = sd_event_source_unref(s->dev_kmsg_event_source);
+ return 0;
+ }
+
+ if (ERRNO_IS_TRANSIENT(errno) || errno == EPIPE)
+ return 0;
+
+ return log_error_errno(errno, "Failed to read from /dev/kmsg: %m");
+ }
+
+ dev_kmsg_record(s, buffer, l);
+ return 1;
+}
+
+int server_flush_dev_kmsg(Server *s) {
+ int r;
+
+ assert(s);
+
+ if (s->dev_kmsg_fd < 0)
+ return 0;
+
+ if (!s->dev_kmsg_readable)
+ return 0;
+
+ log_debug("Flushing /dev/kmsg...");
+
+ for (;;) {
+ r = server_read_dev_kmsg(s);
+ if (r < 0)
+ return r;
+
+ if (r == 0)
+ break;
+ }
+
+ return 0;
+}
+
+static int dispatch_dev_kmsg(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
+ Server *s = ASSERT_PTR(userdata);
+
+ assert(es);
+ assert(fd == s->dev_kmsg_fd);
+
+ if (revents & EPOLLERR)
+ log_warning("/dev/kmsg buffer overrun, some messages lost.");
+
+ if (!(revents & EPOLLIN))
+ log_error("Got invalid event from epoll for /dev/kmsg: %"PRIx32, revents);
+
+ return server_read_dev_kmsg(s);
+}
+
+int server_open_dev_kmsg(Server *s) {
+ mode_t mode;
+ int r;
+
+ assert(s);
+
+ if (s->read_kmsg)
+ mode = O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY;
+ else
+ mode = O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY;
+
+ s->dev_kmsg_fd = open("/dev/kmsg", mode);
+ if (s->dev_kmsg_fd < 0) {
+ log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING,
+ errno, "Failed to open /dev/kmsg, ignoring: %m");
+ return 0;
+ }
+
+ if (!s->read_kmsg)
+ return 0;
+
+ r = sd_event_add_io(s->event, &s->dev_kmsg_event_source, s->dev_kmsg_fd, EPOLLIN, dispatch_dev_kmsg, s);
+ if (r < 0) {
+
+ /* This will fail with EPERM on older kernels where
+ * /dev/kmsg is not readable. */
+ if (r == -EPERM) {
+ r = 0;
+ goto fail;
+ }
+
+ log_error_errno(r, "Failed to add /dev/kmsg fd to event loop: %m");
+ goto fail;
+ }
+
+ r = sd_event_source_set_priority(s->dev_kmsg_event_source, SD_EVENT_PRIORITY_IMPORTANT+10);
+ if (r < 0) {
+ log_error_errno(r, "Failed to adjust priority of kmsg event source: %m");
+ goto fail;
+ }
+
+ s->dev_kmsg_readable = true;
+
+ return 0;
+
+fail:
+ s->dev_kmsg_event_source = sd_event_source_unref(s->dev_kmsg_event_source);
+ s->dev_kmsg_fd = safe_close(s->dev_kmsg_fd);
+
+ return r;
+}
+
+int server_open_kernel_seqnum(Server *s) {
+ _cleanup_close_ int fd = -1;
+ const char *fn;
+ uint64_t *p;
+ int r;
+
+ assert(s);
+
+ /* We store the seqnum we last read in an mmapped file. That way we can just use it like a variable,
+ * but it is persistent and automatically flushed at reboot. */
+
+ if (!s->read_kmsg)
+ return 0;
+
+ fn = strjoina(s->runtime_directory, "/kernel-seqnum");
+ fd = open(fn, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0644);
+ if (fd < 0) {
+ log_error_errno(errno, "Failed to open %s, ignoring: %m", fn);
+ return 0;
+ }
+
+ r = posix_fallocate_loop(fd, 0, sizeof(uint64_t));
+ if (r < 0) {
+ log_error_errno(r, "Failed to allocate sequential number file, ignoring: %m");
+ return 0;
+ }
+
+ p = mmap(NULL, sizeof(uint64_t), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+ if (p == MAP_FAILED) {
+ log_error_errno(errno, "Failed to map sequential number file, ignoring: %m");
+ return 0;
+ }
+
+ s->kernel_seqnum = p;
+
+ return 0;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 14:59:00 +0000