bus: add new API for kdbus memfd functionality

3 files changed, 293 insertions, 1 deletions

diff --git a/src/libsystemd-bus/kdbus.h b/src/libsystemd-bus/kdbus.h
index a8922c76e3..bb339ae69c 100644
--- a/src/libsystemd-bus/kdbus.h
+++ b/src/libsystemd-bus/kdbus.h
@@ -424,7 +424,7 @@ enum kdbus_cmd {
 
 	/* kdbus memfd commands: */
 	KDBUS_CMD_MEMFD_SIZE_GET =	_IOWR(KDBUS_IOC_MAGIC, 0x81, __u64 *),
-	KDBUS_CMD_MEMFD_SIZE_SET =	_IOWR(KDBUS_IOC_MAGIC, 0x82, __u64),
+	KDBUS_CMD_MEMFD_SIZE_SET =	_IOWR(KDBUS_IOC_MAGIC, 0x82, __u64 *),
 	KDBUS_CMD_MEMFD_SEAL_GET =	_IOWR(KDBUS_IOC_MAGIC, 0x83, int *),
 	KDBUS_CMD_MEMFD_SEAL_SET =	_IOWR(KDBUS_IOC_MAGIC, 0x84, int),
 };
diff --git a/src/libsystemd-bus/sd-memfd.c b/src/libsystemd-bus/sd-memfd.c
new file mode 100644
index 0000000000..51b111e8b5
--- /dev/null
+++ b/src/libsystemd-bus/sd-memfd.c
@@ -0,0 +1,207 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 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 <stdio.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+
+#include "util.h"
+#include "kdbus.h"
+
+#include "sd-memfd.h"
+
+struct sd_memfd {
+        int fd;
+        FILE *f;
+};
+
+int sd_memfd_new(sd_memfd **m) {
+        _cleanup_close_ int kdbus = -1;
+        sd_memfd *n;
+        int fd;
+
+        if (!m)
+                return -EINVAL;
+
+        kdbus = open("/dev/kdbus/control", O_RDWR|O_NOCTTY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        if (ioctl(kdbus, KDBUS_CMD_MEMFD_NEW, &fd) < 0)
+                return -errno;
+
+        n = new0(struct sd_memfd, 1);
+        if (!n)
+                return -ENOMEM;
+
+        n->fd = fd;
+        *m = n;
+        return 0;
+}
+
+int sd_memfd_make(int fd, sd_memfd **m) {
+        sd_memfd *n;
+        uint64_t sz;
+
+        if (!m)
+                return -EINVAL;
+        if (fd < 0)
+                return -EINVAL;
+
+        /* Check if this is a valid memfd */
+        if (ioctl(fd, KDBUS_CMD_MEMFD_SIZE_GET, &sz) < 0)
+                return -ENOTTY;
+
+        n = new0(struct sd_memfd, 1);
+        if (!n)
+                return -ENOMEM;
+
+        n->fd = fd;
+        *m = n;
+
+        return 0;
+}
+
+void sd_memfd_free(sd_memfd *m) {
+        if (!m)
+                return;
+
+        if (m->f)
+                fclose(m->f);
+        else
+                close_nointr_nofail(m->fd);
+
+        free(m);
+}
+
+int sd_memfd_get_fd(sd_memfd *m) {
+        if (!m)
+                return -EINVAL;
+
+        return m->fd;
+}
+
+int sd_memfd_get_file(sd_memfd *m, FILE **f) {
+        if (!m)
+                return -EINVAL;
+        if (!f)
+                return -EINVAL;
+
+        if (!m->fd) {
+                m->f = fdopen(m->fd, "r+");
+                if (!m->f)
+                        return -errno;
+        }
+
+        *f = m->f;
+        return 0;
+}
+
+int sd_memfd_dup_fd(sd_memfd *m) {
+        int fd;
+
+        if (!m)
+                return -EINVAL;
+
+        fd = fcntl(m->fd, F_DUPFD_CLOEXEC, 3);
+        if (fd < 0)
+                return -errno;
+
+        return fd;
+}
+
+int sd_memfd_map(sd_memfd *m, uint64_t offset, size_t size, void **p) {
+        void *q;
+        int sealed;
+
+        if (!m)
+                return -EINVAL;
+        if (size <= 0)
+                return -EINVAL;
+        if (!p)
+                return -EINVAL;
+
+        sealed = sd_memfd_get_sealed(m);
+        if (sealed < 0)
+                return sealed;
+
+        q = mmap(NULL, size, sealed ? PROT_READ : PROT_READ|PROT_WRITE, MAP_SHARED, m->fd, offset);
+        if (q == MAP_FAILED)
+                return -errno;
+
+        *p = q;
+        return 0;
+}
+
+int sd_memfd_set_sealed(sd_memfd *m, int b) {
+        int r;
+
+        if (!m)
+                return -EINVAL;
+
+        r = ioctl(m->fd, KDBUS_CMD_MEMFD_SEAL_SET, b);
+        if (r < 0)
+                return -errno;
+
+        return 0;
+}
+
+int sd_memfd_get_sealed(sd_memfd *m) {
+        int r, b;
+
+        if (!m)
+                return -EINVAL;
+
+        r = ioctl(m->fd, KDBUS_CMD_MEMFD_SEAL_GET, &b);
+        if (r < 0)
+                return -errno;
+
+        return !!b;
+}
+
+int sd_memfd_get_size(sd_memfd *m, uint64_t *sz) {
+        int r;
+
+        if (!m)
+                return -EINVAL;
+        if (!sz)
+                return -EINVAL;
+
+        r = ioctl(m->fd, KDBUS_CMD_MEMFD_SIZE_GET, sz);
+        if (r < 0)
+                return -errno;
+
+        return r;
+}
+
+int sd_memfd_set_size(sd_memfd *m, uint64_t sz) {
+        int r;
+
+        if (!m)
+                return -EINVAL;
+
+        r = ioctl(m->fd, KDBUS_CMD_MEMFD_SIZE_SET, &sz);
+        if (r < 0)
+                return -errno;
+
+        return r;
+}
diff --git a/src/libsystemd-bus/test-bus-memfd.c b/src/libsystemd-bus/test-bus-memfd.c
new file mode 100644
index 0000000000..4c5ae21a8c
--- /dev/null
+++ b/src/libsystemd-bus/test-bus-memfd.c
@@ -0,0 +1,85 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 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 <sys/mman.h>
+
+#include "log.h"
+#include "macro.h"
+#include "util.h"
+
+#include "sd-memfd.h"
+
+int main(int argc, char *argv[]) {
+        sd_memfd *m;
+        char *s;
+        uint64_t sz;
+        int r, fd;
+
+        log_set_max_level(LOG_DEBUG);
+
+        r = sd_memfd_new(&m);
+        if (r == -ENOENT)
+                return EXIT_TEST_SKIP;
+
+        r = sd_memfd_map(m, 0, 6, (void**) &s);
+        assert_se(r >= 0);
+
+        strcpy(s, "hallo");
+        assert_se(munmap(s, 6) == 0);
+
+        assert_se(write(sd_memfd_get_fd(m), "he", 2) == 2);
+
+        r = sd_memfd_get_sealed(m);
+        assert_se(r == 0);
+
+        r = sd_memfd_set_sealed(m, 1);
+        assert_se(r >= 0);
+
+        r = sd_memfd_get_sealed(m);
+        assert_se(r == 1);
+
+        r = sd_memfd_get_size(m, &sz);
+        assert_se(r >= 0);
+        assert_se(sz = page_size());
+
+        r = sd_memfd_set_size(m, 6);
+        assert_se(r >= 0);
+
+        fd = sd_memfd_dup_fd(m);
+        assert_se(fd >= 0);
+
+        sd_memfd_free(m);
+
+        r = sd_memfd_make(fd, &m);
+        assert_se(r >= 0);
+
+        r = sd_memfd_get_size(m, &sz);
+        assert_se(r >= 0);
+        assert_se(sz = 6);
+
+        r = sd_memfd_map(m, 0, 6, (void**) &s);
+        assert_se(r >= 0);
+
+        assert_se(streq(s, "hello"));
+        assert_se(munmap(s, 6) == 0);
+
+        return 0;
+}