journald: split /dev/kmsg related stuff into its own .c file

1 files changed, 437 insertions, 0 deletions

diff --git a/src/journal/journald-kmsg.c b/src/journal/journald-kmsg.c
new file mode 100644
index 0000000000..cc0080da19
--- /dev/null
+++ b/src/journal/journald-kmsg.c
@@ -0,0 +1,437 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2011 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <unistd.h>
+#include <sys/epoll.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+
+#include <systemd/sd-messages.h>
+#include <libudev.h>
+
+#include "journald.h"
+#include "journald-kmsg.h"
+
+void server_forward_kmsg(
+        Server *s,
+        int priority,
+        const char *identifier,
+        const char *message,
+        struct ucred *ucred) {
+
+        struct iovec iovec[5];
+        char header_priority[6], header_pid[16];
+        int n = 0;
+        char *ident_buf = NULL;
+
+        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 */
+        snprintf(header_priority, sizeof(header_priority), "<%i>", priority);
+        char_array_0(header_priority);
+        IOVEC_SET_STRING(iovec[n++], header_priority);
+
+        /* Second: identifier and PID */
+        if (ucred) {
+                if (!identifier) {
+                        get_process_comm(ucred->pid, &ident_buf);
+                        identifier = ident_buf;
+                }
+
+                snprintf(header_pid, sizeof(header_pid), "[%lu]: ", (unsigned long) ucred->pid);
+                char_array_0(header_pid);
+
+                if (identifier)
+                        IOVEC_SET_STRING(iovec[n++], identifier);
+
+                IOVEC_SET_STRING(iovec[n++], header_pid);
+        } else if (identifier) {
+                IOVEC_SET_STRING(iovec[n++], identifier);
+                IOVEC_SET_STRING(iovec[n++], ": ");
+        }
+
+        /* Fourth: message */
+        IOVEC_SET_STRING(iovec[n++], message);
+        IOVEC_SET_STRING(iovec[n++], "\n");
+
+        if (writev(s->dev_kmsg_fd, iovec, n) < 0)
+                log_debug("Failed to write to /dev/kmsg for logging: %s", strerror(errno));
+
+        free(ident_buf);
+}
+
+static bool is_us(const char *pid) {
+        pid_t t;
+
+        assert(pid);
+
+        if (parse_pid(pid, &t) < 0)
+                return false;
+
+        return t == getpid();
+}
+
+static void dev_kmsg_record(Server *s, char *p, size_t l) {
+        struct iovec iovec[N_IOVEC_META_FIELDS + 7 + N_IOVEC_KERNEL_FIELDS + 2 + N_IOVEC_UDEV_FIELDS];
+        char *message = NULL, *syslog_priority = NULL, *syslog_pid = NULL, *syslog_facility = NULL, *syslog_identifier = NULL, *source_time = NULL;
+        int priority, r;
+        unsigned n = 0, z = 0, j;
+        usec_t usec;
+        char *identifier = NULL, *pid = NULL, *e, *f, *k;
+        uint64_t serial;
+        size_t pl;
+        char *kernel_device = 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 && (priority & LOG_FACMASK) != 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, SD_MESSAGE_JOURNAL_MISSED, "Missed %llu kernel messages", (unsigned long long) serial - *s->kernel_seqnum - 1);
+
+                /* 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 = parse_usec(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;
+                /* Meta data fields attached */
+
+                if (*k != ' ')
+                        break;
+
+                k ++, l --;
+
+                e = memchr(k, '\n', l);
+                if (!e)
+                        return;
+
+                *e = 0;
+
+                m = cunescape_length_with_prefix(k, e - k, "_KERNEL_");
+                if (!m)
+                        break;
+
+                if (startswith(m, "_KERNEL_DEVICE="))
+                        kernel_device = m + 15;
+
+                IOVEC_SET_STRING(iovec[n++], m);
+                z++;
+
+                l -= (e - k) + 1;
+                k = e + 1;
+        }
+
+        if (kernel_device) {
+                struct udev_device *ud;
+
+                ud = udev_device_new_from_device_id(s->udev, kernel_device);
+                if (ud) {
+                        const char *g;
+                        struct udev_list_entry *ll;
+                        char *b;
+
+                        g = udev_device_get_devnode(ud);
+                        if (g) {
+                                b = strappend("_UDEV_DEVNODE=", g);
+                                if (b) {
+                                        IOVEC_SET_STRING(iovec[n++], b);
+                                        z++;
+                                }
+                        }
+
+                        g = udev_device_get_sysname(ud);
+                        if (g) {
+                                b = strappend("_UDEV_SYSNAME=", g);
+                                if (b) {
+                                        IOVEC_SET_STRING(iovec[n++], b);
+                                        z++;
+                                }
+                        }
+
+                        j = 0;
+                        ll = udev_device_get_devlinks_list_entry(ud);
+                        udev_list_entry_foreach(ll, ll) {
+
+                                if (j > N_IOVEC_UDEV_FIELDS)
+                                        break;
+
+                                g = udev_list_entry_get_name(ll);
+                                b = strappend("_UDEV_DEVLINK=", g);
+                                if (g) {
+                                        IOVEC_SET_STRING(iovec[n++], b);
+                                        z++;
+                                }
+
+                                j++;
+                        }
+
+                        udev_device_unref(ud);
+                }
+        }
+
+        if (asprintf(&source_time, "_SOURCE_MONOTONIC_TIMESTAMP=%llu",
+                     (unsigned long long) usec) >= 0)
+                IOVEC_SET_STRING(iovec[n++], source_time);
+
+        IOVEC_SET_STRING(iovec[n++], "_TRANSPORT=kernel");
+
+        if (asprintf(&syslog_priority, "PRIORITY=%i", priority & LOG_PRIMASK) >= 0)
+                IOVEC_SET_STRING(iovec[n++], syslog_priority);
+
+        if ((priority & LOG_FACMASK) == LOG_KERN)
+                IOVEC_SET_STRING(iovec[n++], "SYSLOG_IDENTIFIER=kernel");
+        else {
+                syslog_read_identifier((const char**) &p, &identifier, &pid);
+
+                /* Avoid any messages we generated ourselves via
+                 * log_info() and friends. */
+                if (pid && is_us(pid))
+                        goto finish;
+
+                if (identifier) {
+                        syslog_identifier = strappend("SYSLOG_IDENTIFIER=", identifier);
+                        if (syslog_identifier)
+                                IOVEC_SET_STRING(iovec[n++], syslog_identifier);
+                }
+
+                if (pid) {
+                        syslog_pid = strappend("SYSLOG_PID=", pid);
+                        if (syslog_pid)
+                                IOVEC_SET_STRING(iovec[n++], syslog_pid);
+                }
+
+                if (asprintf(&syslog_facility, "SYSLOG_FACILITY=%i", LOG_FAC(priority)) >= 0)
+                        IOVEC_SET_STRING(iovec[n++], syslog_facility);
+        }
+
+        message = cunescape_length_with_prefix(p, pl, "MESSAGE=");
+        if (message)
+                IOVEC_SET_STRING(iovec[n++], message);
+
+        server_dispatch_message(s, iovec, n, ELEMENTSOF(iovec), NULL, NULL, NULL, 0, NULL, priority);
+
+finish:
+        for (j = 0; j < z; j++)
+                free(iovec[j].iov_base);
+
+        free(message);
+        free(syslog_priority);
+        free(syslog_identifier);
+        free(syslog_pid);
+        free(syslog_facility);
+        free(source_time);
+        free(identifier);
+        free(pid);
+}
+
+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) {
+                        epoll_ctl(s->epoll_fd, EPOLL_CTL_DEL, s->dev_kmsg_fd, NULL);
+                        return 0;
+                }
+
+                if (errno == EAGAIN || errno == EINTR || errno == EPIPE)
+                        return 0;
+
+                log_error("Failed to read from kernel: %m");
+                return -errno;
+        }
+
+        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_info("Flushing /dev/kmsg...");
+
+        for (;;) {
+                r = server_read_dev_kmsg(s);
+                if (r < 0)
+                        return r;
+
+                if (r == 0)
+                        break;
+        }
+
+        return 0;
+}
+
+int server_open_dev_kmsg(Server *s) {
+        struct epoll_event ev;
+
+        assert(s);
+
+        s->dev_kmsg_fd = open("/dev/kmsg", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
+        if (s->dev_kmsg_fd < 0) {
+                log_warning("Failed to open /dev/kmsg, ignoring: %m");
+                return 0;
+        }
+
+        zero(ev);
+        ev.events = EPOLLIN;
+        ev.data.fd = s->dev_kmsg_fd;
+        if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, s->dev_kmsg_fd, &ev) < 0) {
+
+                /* This will fail with EPERM on older kernels where
+                 * /dev/kmsg is not readable. */
+                if (errno == EPERM)
+                        return 0;
+
+                log_error("Failed to add /dev/kmsg fd to epoll object: %m");
+                return -errno;
+        }
+
+        s->dev_kmsg_readable = true;
+
+        return 0;
+}
+
+int server_open_kernel_seqnum(Server *s) {
+        int fd;
+        uint64_t *p;
+
+        assert(s);
+
+        /* We store the seqnum we last read in an mmaped file. That
+         * way we can just use it like a variable, but it is
+         * persistant and automatically flushed at reboot. */
+
+        fd = open("/run/systemd/journal/kernel-seqnum", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0644);
+        if (fd < 0) {
+                log_error("Failed to open /run/systemd/journal/kernel-seqnum, ignoring: %m");
+                return 0;
+        }
+
+        if (posix_fallocate(fd, 0, sizeof(uint64_t)) < 0) {
+                log_error("Failed to allocate sequential number file, ignoring: %m");
+                close_nointr_nofail(fd);
+                return 0;
+        }
+
+        p = mmap(NULL, sizeof(uint64_t), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+        if (p == MAP_FAILED) {
+                log_error("Failed to map sequential number file, ignoring: %m");
+                close_nointr_nofail(fd);
+                return 0;
+        }
+
+        close_nointr_nofail(fd);
+        s->kernel_seqnum = p;
+
+        return 0;
+}