chiark / gitweb /
journal: fix bad memory access
[elogind.git] / src / journal / journald.c
index d02030939af0ec2907e52ee182ae852ba5d42d67..39263bfe4c41530e9431396f91886b4f68d95cba 100644 (file)
@@ -25,8 +25,6 @@
 #include <sys/signalfd.h>
 #include <unistd.h>
 #include <fcntl.h>
-#include <sys/acl.h>
-#include <acl/libacl.h>
 #include <stddef.h>
 #include <sys/ioctl.h>
 #include <linux/sockios.h>
@@ -40,7 +38,6 @@
 #include "hashmap.h"
 #include "journal-file.h"
 #include "socket-util.h"
-#include "acl-util.h"
 #include "cgroup-util.h"
 #include "list.h"
 #include "journal-rate-limit.h"
 #include "journald.h"
 #include "virt.h"
 
+#ifdef HAVE_ACL
+#include <sys/acl.h>
+#include <acl/libacl.h>
+#include "acl-util.h"
+#endif
+
+#ifdef HAVE_SELINUX
+#include <selinux/selinux.h>
+#endif
+
 #define USER_JOURNALS_MAX 1024
 #define STDOUT_STREAMS_MAX 4096
 
@@ -61,7 +68,9 @@
 
 #define SYSLOG_TIMEOUT_USEC (250*USEC_PER_MSEC)
 
-#define N_IOVEC_META_FIELDS 16
+#define N_IOVEC_META_FIELDS 17
+
+#define ENTRY_SIZE_MAX (1024*1024*32)
 
 typedef enum StdoutStreamState {
         STDOUT_STREAM_IDENTIFIER,
@@ -180,18 +189,42 @@ finish:
         return avail;
 }
 
-static void fix_perms(JournalFile *f, uid_t uid) {
+static void server_read_file_gid(Server *s) {
+        const char *adm = "adm";
+        int r;
+
+        assert(s);
+
+        if (s->file_gid_valid)
+                return;
+
+        r = get_group_creds(&adm, &s->file_gid);
+        if (r < 0)
+                log_warning("Failed to resolve 'adm' group: %s", strerror(-r));
+
+        /* if we couldn't read the gid, then it will be 0, but that's
+         * fine and we shouldn't try to resolve the group again, so
+         * let's just pretend it worked right-away. */
+        s->file_gid_valid = true;
+}
+
+static void server_fix_perms(Server *s, JournalFile *f, uid_t uid) {
+        int r;
+#ifdef HAVE_ACL
         acl_t acl;
         acl_entry_t entry;
         acl_permset_t permset;
-        int r;
+#endif
 
         assert(f);
 
-        r = fchmod_and_fchown(f->fd, 0640, 0, 0);
+        server_read_file_gid(s);
+
+        r = fchmod_and_fchown(f->fd, 0640, 0, s->file_gid);
         if (r < 0)
                 log_warning("Failed to fix access mode/rights on %s, ignoring: %s", f->path, strerror(-r));
 
+#ifdef HAVE_ACL
         if (uid <= 0)
                 return;
 
@@ -224,6 +257,7 @@ static void fix_perms(JournalFile *f, uid_t uid) {
 
 finish:
         acl_free(acl);
+#endif
 }
 
 static JournalFile* find_journal(Server *s, uid_t uid) {
@@ -270,7 +304,7 @@ static JournalFile* find_journal(Server *s, uid_t uid) {
         if (r < 0)
                 return s->system_journal;
 
-        fix_perms(f, uid);
+        server_fix_perms(s, f, uid);
         f->metrics = s->system_metrics;
         f->compress = s->compress;
 
@@ -408,7 +442,7 @@ static void dispatch_message_real(Server *s,
                 *comm = NULL, *cmdline = NULL, *hostname = NULL,
                 *audit_session = NULL, *audit_loginuid = NULL,
                 *exe = NULL, *cgroup = NULL, *session = NULL,
-                *owner_uid = NULL, *unit = NULL;
+                *owner_uid = NULL, *unit = NULL, *selinux_context = NULL;
 
         char idbuf[33];
         sd_id128_t id;
@@ -426,6 +460,9 @@ static void dispatch_message_real(Server *s,
         if (ucred) {
                 uint32_t audit;
                 uid_t owner;
+#ifdef HAVE_SELINUX
+                security_context_t con;
+#endif
 
                 realuid = ucred->uid;
 
@@ -452,7 +489,7 @@ static void dispatch_message_real(Server *s,
                         exe = strappend("_EXE=", t);
                         free(t);
 
-                        if (comm)
+                        if (exe)
                                 IOVEC_SET_STRING(iovec[n++], exe);
                 }
 
@@ -503,6 +540,16 @@ static void dispatch_message_real(Server *s,
                 if (sd_pid_get_owner_uid(ucred->uid, &owner) >= 0)
                         if (asprintf(&owner_uid, "_SYSTEMD_OWNER_UID=%lu", (unsigned long) owner) >= 0)
                                 IOVEC_SET_STRING(iovec[n++], owner_uid);
+
+#ifdef HAVE_SELINUX
+                if (getpidcon(ucred->pid, &con) >= 0) {
+                        selinux_context = strappend("_SELINUX_CONTEXT=", con);
+                        if (selinux_context)
+                                IOVEC_SET_STRING(iovec[n++], selinux_context);
+
+                        freecon(con);
+                }
+#endif
         }
 
         if (tv) {
@@ -574,6 +621,7 @@ retry:
         free(session);
         free(owner_uid);
         free(unit);
+        free(selinux_context);
 }
 
 static void driver_message(Server *s, sd_id128_t message_id, const char *format, ...) {
@@ -706,6 +754,11 @@ static void forward_syslog_iovec(Server *s, const struct iovec *iovec, unsigned
         if (sendmsg(s->syslog_fd, &msghdr, MSG_NOSIGNAL) >= 0)
                 return;
 
+        /* The socket is full? I guess the syslog implementation is
+         * too slow, and we shouldn't wait for that... */
+        if (errno == EAGAIN)
+                return;
+
         if (ucred && errno == ESRCH) {
                 struct ucred u;
 
@@ -719,6 +772,9 @@ static void forward_syslog_iovec(Server *s, const struct iovec *iovec, unsigned
 
                 if (sendmsg(s->syslog_fd, &msghdr, MSG_NOSIGNAL) >= 0)
                         return;
+
+                if (errno == EAGAIN)
+                        return;
         }
 
         log_debug("Failed to forward syslog message: %m");
@@ -1237,6 +1293,52 @@ finish:
         free(message);
 }
 
+static void process_native_file(Server *s, int fd, struct ucred *ucred, struct timeval *tv) {
+        struct stat st;
+        void *p;
+        ssize_t n;
+
+        assert(s);
+        assert(fd >= 0);
+
+        /* Data is in the passed file, since it didn't fit in a
+         * datagram. We can't map the file here, since clients might
+         * then truncate it and trigger a SIGBUS for us. So let's
+         * stupidly read it */
+
+        if (fstat(fd, &st) < 0) {
+                log_error("Failed to stat passed file, ignoring: %m");
+                return;
+        }
+
+        if (!S_ISREG(st.st_mode)) {
+                log_error("File passed is not regular. Ignoring.");
+                return;
+        }
+
+        if (st.st_size <= 0)
+                return;
+
+        if (st.st_size > ENTRY_SIZE_MAX) {
+                log_error("File passed too large. Ignoring.");
+                return;
+        }
+
+        p = malloc(st.st_size);
+        if (!p) {
+                log_error("Out of memory");
+                return;
+        }
+
+        n = pread(fd, p, st.st_size, 0);
+        if (n < 0)
+                log_error("Failed to read file, ignoring: %s", strerror(-n));
+        else if (n > 0)
+                process_native_message(s, p, n, ucred, tv);
+
+        free(p);
+}
+
 static int stdout_stream_log(StdoutStream *s, const char *p) {
         struct iovec iovec[N_IOVEC_META_FIELDS + 5];
         char *message = NULL, *syslog_priority = NULL, *syslog_facility = NULL, *syslog_identifier = NULL;
@@ -1246,6 +1348,9 @@ static int stdout_stream_log(StdoutStream *s, const char *p) {
         assert(s);
         assert(p);
 
+        if (isempty(p))
+                return 0;
+
         priority = s->priority;
 
         if (s->level_prefix)
@@ -1595,6 +1700,9 @@ static void proc_kmsg_line(Server *s, const char *p) {
         assert(s);
         assert(p);
 
+        if (isempty(p))
+                return;
+
         parse_syslog_priority((char **) &p, &priority);
 
         if (s->forward_to_kmsg && (priority & LOG_FACMASK) != LOG_KERN)
@@ -1643,7 +1751,6 @@ static void proc_kmsg_line(Server *s, const char *p) {
         if (message)
                 IOVEC_SET_STRING(iovec[n++], message);
 
-
         dispatch_message(s, iovec, n, ELEMENTSOF(iovec), NULL, NULL, priority);
 
         free(message);
@@ -1726,7 +1833,7 @@ static int system_journal_open(Server *s) {
                         s->system_journal->metrics = s->system_metrics;
                         s->system_journal->compress = s->compress;
 
-                        fix_perms(s->system_journal, 0);
+                        server_fix_perms(s, s->system_journal, 0);
                 } else if (r < 0) {
 
                         if (r != -ENOENT && r != -EROFS)
@@ -1779,7 +1886,7 @@ static int system_journal_open(Server *s) {
                         s->runtime_journal->metrics = s->runtime_metrics;
                         s->runtime_journal->compress = s->compress;
 
-                        fix_perms(s->runtime_journal, 0);
+                        server_fix_perms(s, s->runtime_journal, 0);
                 }
         }
 
@@ -1973,19 +2080,19 @@ static int process_event(Server *s, struct epoll_event *ev) {
                         union {
                                 struct cmsghdr cmsghdr;
                                 uint8_t buf[CMSG_SPACE(sizeof(struct ucred)) +
-                                            CMSG_SPACE(sizeof(struct timeval))];
+                                            CMSG_SPACE(sizeof(struct timeval)) +
+                                            CMSG_SPACE(sizeof(int))];
                         } control;
                         ssize_t n;
                         int v;
+                        int *fds = NULL;
+                        unsigned n_fds = 0;
 
                         if (ioctl(ev->data.fd, SIOCINQ, &v) < 0) {
                                 log_error("SIOCINQ failed: %m");
                                 return -errno;
                         }
 
-                        if (v <= 0)
-                                return 1;
-
                         if (s->buffer_size < (size_t) v) {
                                 void *b;
                                 size_t l;
@@ -2013,7 +2120,7 @@ static int process_event(Server *s, struct epoll_event *ev) {
                         msghdr.msg_control = &control;
                         msghdr.msg_controllen = sizeof(control);
 
-                        n = recvmsg(ev->data.fd, &msghdr, MSG_DONTWAIT);
+                        n = recvmsg(ev->data.fd, &msghdr, MSG_DONTWAIT|MSG_CMSG_CLOEXEC);
                         if (n < 0) {
 
                                 if (errno == EINTR || errno == EAGAIN)
@@ -2033,20 +2140,37 @@ static int process_event(Server *s, struct epoll_event *ev) {
                                          cmsg->cmsg_type == SO_TIMESTAMP &&
                                          cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
                                         tv = (struct timeval*) CMSG_DATA(cmsg);
+                                else if (cmsg->cmsg_level == SOL_SOCKET &&
+                                         cmsg->cmsg_type == SCM_RIGHTS) {
+                                        fds = (int*) CMSG_DATA(cmsg);
+                                        n_fds = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
+                                }
                         }
 
                         if (ev->data.fd == s->syslog_fd) {
                                 char *e;
 
-                                e = memchr(s->buffer, '\n', n);
-                                if (e)
-                                        *e = 0;
-                                else
-                                        s->buffer[n] = 0;
+                                if (n > 0 && n_fds == 0) {
+                                        e = memchr(s->buffer, '\n', n);
+                                        if (e)
+                                                *e = 0;
+                                        else
+                                                s->buffer[n] = 0;
+
+                                        process_syslog_message(s, strstrip(s->buffer), ucred, tv);
+                                } else if (n_fds > 0)
+                                        log_warning("Got file descriptors via syslog socket. Ignoring.");
+
+                        } else {
+                                if (n > 0 && n_fds == 0)
+                                        process_native_message(s, s->buffer, n, ucred, tv);
+                                else if (n == 0 && n_fds == 1)
+                                        process_native_file(s, fds[0], ucred, tv);
+                                else if (n_fds > 0)
+                                        log_warning("Got too many file descriptors via native socket. Ignoring.");
+                        }
 
-                                process_syslog_message(s, strstrip(s->buffer), ucred, tv);
-                        } else
-                                process_native_message(s, s->buffer, n, ucred, tv);
+                        close_many(fds, n_fds);
                 }
 
                 return 1;