From: "M. Mohan Kumar" <mo...@in.ibm.com>
Add interfaces to open and create files for proxy file system driver.
Signed-off-by: M. Mohan Kumar <mo...@in.ibm.com>
---
fsdev/virtfs-proxy-helper.c | 191 ++++++++++++++++++++++++++++++++++++++++++-
hw/9pfs/virtio-9p-proxy.c | 189 +++++++++++++++++++++++++++++++++++++++++--
hw/9pfs/virtio-9p-proxy.h | 11 +++
3 files changed, 382 insertions(+), 9 deletions(-)
diff --git a/fsdev/virtfs-proxy-helper.c b/fsdev/virtfs-proxy-helper.c
index 7670a0e..241fcff 100644
--- a/fsdev/virtfs-proxy-helper.c
+++ b/fsdev/virtfs-proxy-helper.c
@@ -9,6 +9,7 @@
* the COPYING file in the top-level directory.
*/
#include <stdio.h>
+#include <sys/socket.h>
#include <string.h>
#include <sys/un.h>
#include <limits.h>
@@ -27,6 +28,7 @@
#include "qemu-common.h"
#include "virtio-9p-marshal.h"
#include "hw/9pfs/virtio-9p-proxy.h"
+#include "fsdev/virtio-9p-marshal.h"
#define PROGNAME "virtfs-proxy-helper"
@@ -199,6 +201,139 @@ static int read_request(int sockfd, struct iovec *iovec,
ProxyHeader *header)
return 0;
}
+static int send_fd(int sockfd, int fd)
+{
+ struct msghdr msg;
+ struct iovec iov;
+ int retval, data;
+ struct cmsghdr *cmsg;
+ union MsgControl msg_control;
+
+ iov.iov_base = &data;
+ iov.iov_len = sizeof(data);
+
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+ /* No ancillary data on error */
+ if (fd < 0) {
+ /* fd is really negative errno if the request failed */
+ data = fd;
+ } else {
+ data = V9FS_FD_VALID;
+ msg.msg_control = &msg_control;
+ msg.msg_controllen = sizeof(msg_control);
+
+ cmsg = &msg_control.cmsg;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_RIGHTS;
+ memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
+ }
+
+ do {
+ retval = sendmsg(sockfd, &msg, 0);
+ } while (retval < 0 && errno == EINTR);
+ if (fd >= 0) {
+ close(fd);
+ }
+ if (retval < 0) {
+ return retval;
+ }
+ return 0;
+}
+
+/*
+ * from man 7 capabilities, section
+ * Effect of User ID Changes on Capabilities:
+ * 4. If the file system user ID is changed from 0 to nonzero (see setfsuid(2))
+ * then the following capabilities are cleared from the effective set:
+ * CAP_CHOWN, CAP_DAC_OVERRIDE, CAP_DAC_READ_SEARCH, CAP_FOWNER, CAP_FSETID,
+ * CAP_LINUX_IMMUTABLE (since Linux 2.2.30), CAP_MAC_OVERRIDE, and CAP_MKNOD
+ * (since Linux 2.2.30). If the file system UID is changed from nonzero to 0,
+ * then any of these capabilities that are enabled in the permitted set
+ * are enabled in the effective set.
+ */
+static int setfsugid(int uid, int gid)
+{
+ /*
+ * We still need DAC_OVERRIDE because we don't change
+ * supplementary group ids, and hence may be subjected DAC rules
+ */
+ cap_value_t cap_list[] = {
+ CAP_DAC_OVERRIDE,
+ };
+
+ setfsgid(gid);
+ setfsuid(uid);
+
+ if (uid != 0 || gid != 0) {
+ return do_cap_set(cap_list, ARRAY_SIZE(cap_list), 0);
+ }
+ return 0;
+}
+
+/*
+ * create a file and send fd on success
+ * return -errno on error
+ */
+static int do_create(struct iovec *iovec)
+{
+ int ret;
+ V9fsString path;
+ int flags, mode, uid, gid, cur_uid, cur_gid;
+
+ v9fs_string_init(&path);
+ ret = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sdddd",
+ &path, &flags, &mode, &uid, &gid);
+ if (ret < 0) {
+ goto err_out;
+ }
+ cur_uid = geteuid();
+ cur_gid = getegid();
+ ret = setfsugid(uid, gid);
+ if (ret < 0) {
+ /*
+ * On failure reset back to the
+ * old uid/gid
+ */
+ ret = -errno;
+ goto err_out;
+ }
+ ret = open(path.data, flags, mode);
+ if (ret < 0) {
+ ret = -errno;
+ }
+
+err_out:
+ setfsugid(cur_uid, cur_gid);
+ v9fs_string_free(&path);
+ return ret;
+}
+
+/*
+ * open a file and send fd on success
+ * return -errno on error
+ */
+static int do_open(struct iovec *iovec)
+{
+ int flags, ret;
+ V9fsString path;
+
+ v9fs_string_init(&path);
+ ret = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sd", &path, &flags);
+ if (ret < 0) {
+ goto err_out;
+ }
+ ret = open(path.data, flags);
+ if (ret < 0) {
+ ret = -errno;
+ }
+err_out:
+ v9fs_string_free(&path);
+ return ret;
+}
+
static void usage(char *prog)
{
fprintf(stderr, "usage: %s\n"
@@ -208,22 +343,72 @@ static void usage(char *prog)
basename(prog));
}
+static int process_reply(int sock, int type, int retval)
+{
+ switch (type) {
+ case T_OPEN:
+ case T_CREATE:
+ if (send_fd(sock, retval) < 0) {
+ return -1;
+ }
+ break;
+ default:
+ return -1;
+ break;
+ }
+ return 0;
+}
+
static int process_requests(int sock)
{
- int retval;
+ int retval = 0;
ProxyHeader header;
struct iovec in_iovec;
in_iovec.iov_base = g_malloc(PROXY_MAX_IO_SZ + PROXY_HDR_SZ);
in_iovec.iov_len = PROXY_MAX_IO_SZ + PROXY_HDR_SZ;
while (1) {
+ /*
+ * initialize the header type, so that we send
+ * response to proper request type.
+ */
+ header.type = 0;
retval = read_request(sock, &in_iovec, &header);
if (retval < 0) {
- goto error;
+ if (retval == -ENOBUFS) {
+ /*
+ * The request size was too long, we don't
+ * terminate for such errors. We will have
+ * header.type update properly when we reach
+ * here.
+ */
+ if (process_reply(sock, header.type, retval) < 0) {
+ goto err_out;
+ }
+ continue;
+ } else {
+ goto err_out;
+ }
+ }
+
+ switch (header.type) {
+ case T_OPEN:
+ retval = do_open(&in_iovec);
+ break;
+ case T_CREATE:
+ retval = do_create(&in_iovec);
+ break;
+ default:
+ goto err_out;
+ break;
+ }
+
+ if (process_reply(sock, header.type, retval) < 0) {
+ goto err_out;
}
}
(void)socket_write;
-error:
+err_out:
g_free(in_iovec.iov_base);
return -1;
}
diff --git a/hw/9pfs/virtio-9p-proxy.c b/hw/9pfs/virtio-9p-proxy.c
index 3e4dc68..6a74666 100644
--- a/hw/9pfs/virtio-9p-proxy.c
+++ b/hw/9pfs/virtio-9p-proxy.c
@@ -22,6 +22,155 @@ typedef struct V9fsProxy {
struct iovec iovec;
} V9fsProxy;
+/*
+ * Return received file descriptor on success in *status.
+ * errno is also returned on *status (which will be < 0)
+ * return < 0 on transport error.
+ */
+static int v9fs_receivefd(int sockfd, int *status)
+{
+ struct iovec iov;
+ struct msghdr msg;
+ struct cmsghdr *cmsg;
+ int retval, data, fd;
+ union MsgControl msg_control;
+
+ iov.iov_base = &data;
+ iov.iov_len = sizeof(data);
+
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+ msg.msg_control = &msg_control;
+ msg.msg_controllen = sizeof(msg_control);
+
+ do {
+ retval = recvmsg(sockfd, &msg, 0);
+ } while (retval < 0 && errno == EINTR);
+ if (retval <= 0) {
+ return retval;
+ }
+ /*
+ * data is set to V9FS_FD_VALID, if ancillary data is sent. If this
+ * request doesn't need ancillary data (fd) or an error occurred,
+ * data is set to negative errno value.
+ */
+ if (data != V9FS_FD_VALID) {
+ *status = data;
+ return 0;
+ }
+ /*
+ * File descriptor (fd) is sent in the ancillary data. Check if we
+ * indeed received it. One of the reasons to fail to receive it is if
+ * we exceeded the maximum number of file descriptors!
+ */
+ for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+ if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)) ||
+ cmsg->cmsg_level != SOL_SOCKET ||
+ cmsg->cmsg_type != SCM_RIGHTS) {
+ continue;
+ }
+ fd = *((int *)CMSG_DATA(cmsg));
+ *status = fd;
+ return 0;
+ }
+ *status = -ENFILE; /* Ancillary data sent but not received */
+ return 0;
+}
+
+/*
+ * Proxy->header and proxy->request written to socket by QEMU process.
+ * This request read by proxy helper process
+ * returns 0 on success and -errno on error
+ */
+static int v9fs_request(V9fsProxy *proxy, int type,
+ void *response, const char *fmt, ...)
+{
+ va_list ap;
+ int retval = 0;
+ V9fsString *path;
+ ProxyHeader header;
+ struct iovec *iovec = NULL;
+ int flags, mode, uid, gid;
+
+ qemu_mutex_lock(&proxy->mutex);
+
+ if (proxy->sockfd == -1) {
+ retval = -EIO;
+ goto err_out;
+ }
+ iovec = &proxy->iovec;
+
+ va_start(ap, fmt);
+ switch (type) {
+ case T_OPEN:
+ path = va_arg(ap, V9fsString *);
+ flags = va_arg(ap, int);
+ header.size = proxy_marshal(iovec, PROXY_HDR_SZ, "sd", path, flags);
+ if (header.size < 0) {
+ retval = header.size;
+ break;
+ }
+ header.type = T_OPEN;
+ break;
+ case T_CREATE:
+ path = va_arg(ap, V9fsString *);
+ flags = va_arg(ap, int);
+ mode = va_arg(ap, int);
+ uid = va_arg(ap, int);
+ gid = va_arg(ap, int);
+ header.size = proxy_marshal(iovec, PROXY_HDR_SZ, "sdddd", path,
+ flags, mode, uid, gid);
+ if (header.size < 0) {
+ retval = header.size;
+ break;
+ }
+ header.type = T_CREATE;
+ break;
+ default:
+ error_report("Invalid type %d\n", type);
+ retval = -EINVAL;
+ break;
+ }
+ va_end(ap);
+
+ if (retval < 0) {
+ goto err_out;
+ }
+
+ /* marshal the header details */
+ proxy_marshal(iovec, 0, "dd", header.type, header.size);
+ header.size += PROXY_HDR_SZ;
+
+ retval = qemu_write_full(proxy->sockfd, iovec->iov_base, header.size);
+ if (retval != header.size) {
+ goto close_error;
+ }
+
+ switch (type) {
+ case T_OPEN:
+ case T_CREATE:
+ /*
+ * A file descriptor is returned as response for
+ * T_OPEN,T_CREATE on success
+ */
+ if (v9fs_receivefd(proxy->sockfd, &retval) < 0) {
+ goto close_error;
+ }
+ break;
+ }
+
+err_out:
+ qemu_mutex_unlock(&proxy->mutex);
+ return retval;
+
+close_error:
+ close(proxy->sockfd);
+ proxy->sockfd = -1;
+ qemu_mutex_unlock(&proxy->mutex);
+ return -EIO;
+}
+
static int proxy_lstat(FsContext *fs_ctx, V9fsPath *fs_path, struct stat
*stbuf)
{
errno = EOPNOTSUPP;
@@ -48,16 +197,33 @@ static int proxy_closedir(FsContext *ctx, V9fsFidOpenState
*fs)
static int proxy_open(FsContext *ctx, V9fsPath *fs_path,
int flags, V9fsFidOpenState *fs)
{
- fs->fd = -1;
+ fs->fd = v9fs_request(ctx->private, T_OPEN, NULL, "sd", fs_path, flags);
+ if (fs->fd < 0) {
+ errno = -fs->fd;
+ fs->fd = -1;
+ }
return fs->fd;
}
static int proxy_opendir(FsContext *ctx,
V9fsPath *fs_path, V9fsFidOpenState *fs)
{
+ int serrno, fd;
+
fs->dir = NULL;
- errno = EOPNOTSUPP;
- return -1;
+ fd = v9fs_request(ctx->private, T_OPEN, NULL, "sd", fs_path, O_DIRECTORY);
+ if (fd < 0) {
+ errno = -fd;
+ return -1;
+ }
+ fs->dir = fdopendir(fd);
+ if (!fs->dir) {
+ serrno = errno;
+ close(fd);
+ errno = serrno;
+ return -1;
+ }
+ return 0;
}
static void proxy_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
@@ -164,9 +330,20 @@ static int proxy_fstat(FsContext *fs_ctx, int fid_type,
static int proxy_open2(FsContext *fs_ctx, V9fsPath *dir_path, const char *name,
int flags, FsCred *credp, V9fsFidOpenState *fs)
{
- fs->fd = -1;
- errno = EOPNOTSUPP;
- return -1;
+ V9fsString fullname;
+
+ v9fs_string_init(&fullname);
+ v9fs_string_sprintf(&fullname, "%s/%s", dir_path->data, name);
+
+ fs->fd = v9fs_request(fs_ctx->private, T_CREATE, NULL, "sdddd",
+ &fullname, flags, credp->fc_mode,
+ credp->fc_uid, credp->fc_gid);
+ v9fs_string_free(&fullname);
+ if (fs->fd < 0) {
+ errno = -fs->fd;
+ fs->fd = -1;
+ }
+ return fs->fd;
}
diff --git a/hw/9pfs/virtio-9p-proxy.h b/hw/9pfs/virtio-9p-proxy.h
index c33a84b..b8719ea 100644
--- a/hw/9pfs/virtio-9p-proxy.h
+++ b/hw/9pfs/virtio-9p-proxy.h
@@ -13,6 +13,7 @@
#define _QEMU_VIRTIO_9P_PROXY_H
#define PROXY_MAX_IO_SZ (64 * 1024)
+#define V9FS_FD_VALID INT_MAX
/*
* proxy iovec only support one element and
@@ -23,6 +24,11 @@
#define proxy_marshal(out_sg, offset, fmt, args...) \
v9fs_marshal(out_sg, 1, offset, 0, fmt, ##args)
+union MsgControl {
+ struct cmsghdr cmsg;
+ char control[CMSG_SPACE(sizeof(int))];
+};
+
typedef struct {
int type;
int size;
@@ -30,4 +36,9 @@ typedef struct {
#define PROXY_HDR_SZ (sizeof(ProxyHeader))
+enum {
+ T_OPEN = 1,
+ T_CREATE,
+};
+
#endif
--
1.7.6
