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81ffbf5ab1
qemu-e2k/hw/9pfs/9p-local.c
Greg Kurz 81ffbf5ab1 9pfs: local: metadata file for the VirtFS root 
When using the mapped-file security, credentials are stored in a metadata
directory located in the parent directory. This is okay for all paths with
the notable exception of the root path, since we don't want and probably
can't create a metadata directory above the virtfs directory on the host.

This patch introduces a dedicated metadata file, sitting in the virtfs root
for this purpose. It relies on the fact that the "." name necessarily refers
to the virtfs root.

As for the metadata directory, we don't want the client to see this file.
The current code only cares for readdir() but there are many other places
to fix actually. The filtering logic is hence put in a separate function.

Before:

# ls -ld
drwxr-xr-x. 3 greg greg 4096 May  5 12:49 .
# chown root.root .
chown: changing ownership of '.': Is a directory
# ls -ld
drwxr-xr-x. 3 greg greg 4096 May  5 12:49 .

After:

# ls -ld
drwxr-xr-x. 3 greg greg 4096 May  5 12:49 .
# chown root.root .
# ls -ld
drwxr-xr-x. 3 root root 4096 May  5 12:50 .

and from the host:

ls -al .virtfs_metadata_root
-rwx------. 1 greg greg 26 May  5 12:50 .virtfs_metadata_root
$ cat .virtfs_metadata_root
virtfs.uid=0
virtfs.gid=0

Reported-by: Leo Gaspard <leo@gaspard.io>
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Leo Gaspard <leo@gaspard.io>
[groug: work around a patchew false positive in
        local_set_mapped_file_attrat()]
2017-05-25 10:30:14 +02:00

1513 lines
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/*
* 9p Posix callback
*
* Copyright IBM, Corp. 2010
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "9p.h"
#include "9p-local.h"
#include "9p-xattr.h"
#include "9p-util.h"
#include "fsdev/qemu-fsdev.h" /* local_ops */
#include <arpa/inet.h>
#include <pwd.h>
#include <grp.h>
#include <sys/socket.h>
#include <sys/un.h>
#include "qemu/xattr.h"
#include "qemu/cutils.h"
#include "qemu/error-report.h"
#include <libgen.h>
#include <linux/fs.h>
#ifdef CONFIG_LINUX_MAGIC_H
#include <linux/magic.h>
#endif
#include <sys/ioctl.h>
#ifndef XFS_SUPER_MAGIC
#define XFS_SUPER_MAGIC 0x58465342
#endif
#ifndef EXT2_SUPER_MAGIC
#define EXT2_SUPER_MAGIC 0xEF53
#endif
#ifndef REISERFS_SUPER_MAGIC
#define REISERFS_SUPER_MAGIC 0x52654973
#endif
#ifndef BTRFS_SUPER_MAGIC
#define BTRFS_SUPER_MAGIC 0x9123683E
#endif
typedef struct {
int mountfd;
} LocalData;
int local_open_nofollow(FsContext *fs_ctx, const char *path, int flags,
mode_t mode)
{
LocalData *data = fs_ctx->private;
int fd = data->mountfd;
while (*path && fd != -1) {
const char *c;
int next_fd;
char *head;
/* Only relative paths without consecutive slashes */
assert(*path != '/');
head = g_strdup(path);
c = strchrnul(path, '/');
if (*c) {
/* Intermediate path element */
head[c - path] = 0;
path = c + 1;
next_fd = openat_dir(fd, head);
} else {
/* Rightmost path element */
next_fd = openat_file(fd, head, flags, mode);
path = c;
}
g_free(head);
if (fd != data->mountfd) {
close_preserve_errno(fd);
}
fd = next_fd;
}
assert(fd != data->mountfd);
return fd;
}
int local_opendir_nofollow(FsContext *fs_ctx, const char *path)
{
return local_open_nofollow(fs_ctx, path, O_DIRECTORY | O_RDONLY, 0);
}
static void renameat_preserve_errno(int odirfd, const char *opath, int ndirfd,
const char *npath)
{
int serrno = errno;
renameat(odirfd, opath, ndirfd, npath);
errno = serrno;
}
static void unlinkat_preserve_errno(int dirfd, const char *path, int flags)
{
int serrno = errno;
unlinkat(dirfd, path, flags);
errno = serrno;
}
#define VIRTFS_META_DIR ".virtfs_metadata"
#define VIRTFS_META_ROOT_FILE VIRTFS_META_DIR "_root"
static FILE *local_fopenat(int dirfd, const char *name, const char *mode)
{
int fd, o_mode = 0;
FILE *fp;
int flags;
/*
* only supports two modes
*/
if (mode[0] == 'r') {
flags = O_RDONLY;
} else if (mode[0] == 'w') {
flags = O_WRONLY | O_TRUNC | O_CREAT;
o_mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
} else {
return NULL;
}
fd = openat_file(dirfd, name, flags, o_mode);
if (fd == -1) {
return NULL;
}
fp = fdopen(fd, mode);
if (!fp) {
close(fd);
}
return fp;
}
#define ATTR_MAX 100
static void local_mapped_file_attr(int dirfd, const char *name,
struct stat *stbuf)
{
FILE *fp;
char buf[ATTR_MAX];
int map_dirfd;
if (strcmp(name, ".")) {
map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
if (map_dirfd == -1) {
return;
}
fp = local_fopenat(map_dirfd, name, "r");
close_preserve_errno(map_dirfd);
} else {
fp = local_fopenat(dirfd, VIRTFS_META_ROOT_FILE, "r");
}
if (!fp) {
return;
}
memset(buf, 0, ATTR_MAX);
while (fgets(buf, ATTR_MAX, fp)) {
if (!strncmp(buf, "virtfs.uid", 10)) {
stbuf->st_uid = atoi(buf+11);
} else if (!strncmp(buf, "virtfs.gid", 10)) {
stbuf->st_gid = atoi(buf+11);
} else if (!strncmp(buf, "virtfs.mode", 11)) {
stbuf->st_mode = atoi(buf+12);
} else if (!strncmp(buf, "virtfs.rdev", 11)) {
stbuf->st_rdev = atoi(buf+12);
}
memset(buf, 0, ATTR_MAX);
}
fclose(fp);
}
static int local_lstat(FsContext *fs_ctx, V9fsPath *fs_path, struct stat *stbuf)
{
int err = -1;
char *dirpath = g_path_get_dirname(fs_path->data);
char *name = g_path_get_basename(fs_path->data);
int dirfd;
dirfd = local_opendir_nofollow(fs_ctx, dirpath);
if (dirfd == -1) {
goto out;
}
err = fstatat(dirfd, name, stbuf, AT_SYMLINK_NOFOLLOW);
if (err) {
goto err_out;
}
if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
/* Actual credentials are part of extended attrs */
uid_t tmp_uid;
gid_t tmp_gid;
mode_t tmp_mode;
dev_t tmp_dev;
if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.uid", &tmp_uid,
sizeof(uid_t)) > 0) {
stbuf->st_uid = le32_to_cpu(tmp_uid);
}
if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.gid", &tmp_gid,
sizeof(gid_t)) > 0) {
stbuf->st_gid = le32_to_cpu(tmp_gid);
}
if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.mode", &tmp_mode,
sizeof(mode_t)) > 0) {
stbuf->st_mode = le32_to_cpu(tmp_mode);
}
if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.rdev", &tmp_dev,
sizeof(dev_t)) > 0) {
stbuf->st_rdev = le64_to_cpu(tmp_dev);
}
} else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
local_mapped_file_attr(dirfd, name, stbuf);
}
err_out:
close_preserve_errno(dirfd);
out:
g_free(name);
g_free(dirpath);
return err;
}
static int local_set_mapped_file_attrat(int dirfd, const char *name,
FsCred *credp)
{
FILE *fp;
int ret;
char buf[ATTR_MAX];
int uid = -1, gid = -1, mode = -1, rdev = -1;
int map_dirfd = -1, map_fd;
bool is_root = !strcmp(name, ".");
if (is_root) {
fp = local_fopenat(dirfd, VIRTFS_META_ROOT_FILE, "r");
if (!fp) {
if (errno == ENOENT) {
goto update_map_file;
} else {
return -1;
}
}
} else {
ret = mkdirat(dirfd, VIRTFS_META_DIR, 0700);
if (ret < 0 && errno != EEXIST) {
return -1;
}
map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
if (map_dirfd == -1) {
return -1;
}
fp = local_fopenat(map_dirfd, name, "r");
if (!fp) {
if (errno == ENOENT) {
goto update_map_file;
} else {
close_preserve_errno(map_dirfd);
return -1;
}
}
}
memset(buf, 0, ATTR_MAX);
while (fgets(buf, ATTR_MAX, fp)) {
if (!strncmp(buf, "virtfs.uid", 10)) {
uid = atoi(buf + 11);
} else if (!strncmp(buf, "virtfs.gid", 10)) {
gid = atoi(buf + 11);
} else if (!strncmp(buf, "virtfs.mode", 11)) {
mode = atoi(buf + 12);
} else if (!strncmp(buf, "virtfs.rdev", 11)) {
rdev = atoi(buf + 12);
}
memset(buf, 0, ATTR_MAX);
}
fclose(fp);
update_map_file:
if (is_root) {
fp = local_fopenat(dirfd, VIRTFS_META_ROOT_FILE, "w");
} else {
fp = local_fopenat(map_dirfd, name, "w");
/* We can't go this far with map_dirfd not being a valid file descriptor
* but some versions of gcc aren't smart enough to see it.
*/
if (map_dirfd != -1) {
close_preserve_errno(map_dirfd);
}
}
if (!fp) {
return -1;
}
map_fd = fileno(fp);
assert(map_fd != -1);
ret = fchmod(map_fd, 0600);
assert(ret == 0);
if (credp->fc_uid != -1) {
uid = credp->fc_uid;
}
if (credp->fc_gid != -1) {
gid = credp->fc_gid;
}
if (credp->fc_mode != -1) {
mode = credp->fc_mode;
}
if (credp->fc_rdev != -1) {
rdev = credp->fc_rdev;
}
if (uid != -1) {
fprintf(fp, "virtfs.uid=%d\n", uid);
}
if (gid != -1) {
fprintf(fp, "virtfs.gid=%d\n", gid);
}
if (mode != -1) {
fprintf(fp, "virtfs.mode=%d\n", mode);
}
if (rdev != -1) {
fprintf(fp, "virtfs.rdev=%d\n", rdev);
}
fclose(fp);
return 0;
}
static int fchmodat_nofollow(int dirfd, const char *name, mode_t mode)
{
int fd, ret;
/* FIXME: this should be handled with fchmodat(AT_SYMLINK_NOFOLLOW).
* Unfortunately, the linux kernel doesn't implement it yet. As an
* alternative, let's open the file and use fchmod() instead. This
* may fail depending on the permissions of the file, but it is the
* best we can do to avoid TOCTTOU. We first try to open read-only
* in case name points to a directory. If that fails, we try write-only
* in case name doesn't point to a directory.
*/
fd = openat_file(dirfd, name, O_RDONLY, 0);
if (fd == -1) {
/* In case the file is writable-only and isn't a directory. */
if (errno == EACCES) {
fd = openat_file(dirfd, name, O_WRONLY, 0);
}
if (fd == -1 && errno == EISDIR) {
errno = EACCES;
}
}
if (fd == -1) {
return -1;
}
ret = fchmod(fd, mode);
close_preserve_errno(fd);
return ret;
}
static int local_set_xattrat(int dirfd, const char *path, FsCred *credp)
{
int err;
if (credp->fc_uid != -1) {
uint32_t tmp_uid = cpu_to_le32(credp->fc_uid);
err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.uid", &tmp_uid,
sizeof(uid_t), 0);
if (err) {
return err;
}
}
if (credp->fc_gid != -1) {
uint32_t tmp_gid = cpu_to_le32(credp->fc_gid);
err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.gid", &tmp_gid,
sizeof(gid_t), 0);
if (err) {
return err;
}
}
if (credp->fc_mode != -1) {
uint32_t tmp_mode = cpu_to_le32(credp->fc_mode);
err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.mode", &tmp_mode,
sizeof(mode_t), 0);
if (err) {
return err;
}
}
if (credp->fc_rdev != -1) {
uint64_t tmp_rdev = cpu_to_le64(credp->fc_rdev);
err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.rdev", &tmp_rdev,
sizeof(dev_t), 0);
if (err) {
return err;
}
}
return 0;
}
static int local_set_cred_passthrough(FsContext *fs_ctx, int dirfd,
const char *name, FsCred *credp)
{
if (fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
AT_SYMLINK_NOFOLLOW) < 0) {
/*
* If we fail to change ownership and if we are
* using security model none. Ignore the error
*/
if ((fs_ctx->export_flags & V9FS_SEC_MASK) != V9FS_SM_NONE) {
return -1;
}
}
return fchmodat_nofollow(dirfd, name, credp->fc_mode & 07777);
}
static ssize_t local_readlink(FsContext *fs_ctx, V9fsPath *fs_path,
char *buf, size_t bufsz)
{
ssize_t tsize = -1;
if ((fs_ctx->export_flags & V9FS_SM_MAPPED) ||
(fs_ctx->export_flags & V9FS_SM_MAPPED_FILE)) {
int fd;
fd = local_open_nofollow(fs_ctx, fs_path->data, O_RDONLY, 0);
if (fd == -1) {
return -1;
}
do {
tsize = read(fd, (void *)buf, bufsz);
} while (tsize == -1 && errno == EINTR);
close_preserve_errno(fd);
} else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
(fs_ctx->export_flags & V9FS_SM_NONE)) {
char *dirpath = g_path_get_dirname(fs_path->data);
char *name = g_path_get_basename(fs_path->data);
int dirfd;
dirfd = local_opendir_nofollow(fs_ctx, dirpath);
if (dirfd == -1) {
goto out;
}
tsize = readlinkat(dirfd, name, buf, bufsz);
close_preserve_errno(dirfd);
out:
g_free(name);
g_free(dirpath);
}
return tsize;
}
static int local_close(FsContext *ctx, V9fsFidOpenState *fs)
{
return close(fs->fd);
}
static int local_closedir(FsContext *ctx, V9fsFidOpenState *fs)
{
return closedir(fs->dir.stream);
}
static int local_open(FsContext *ctx, V9fsPath *fs_path,
int flags, V9fsFidOpenState *fs)
{
int fd;
fd = local_open_nofollow(ctx, fs_path->data, flags, 0);
if (fd == -1) {
return -1;
}
fs->fd = fd;
return fs->fd;
}
static int local_opendir(FsContext *ctx,
V9fsPath *fs_path, V9fsFidOpenState *fs)
{
int dirfd;
DIR *stream;
dirfd = local_opendir_nofollow(ctx, fs_path->data);
if (dirfd == -1) {
return -1;
}
stream = fdopendir(dirfd);
if (!stream) {
close(dirfd);
return -1;
}
fs->dir.stream = stream;
return 0;
}
static void local_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
{
rewinddir(fs->dir.stream);
}
static off_t local_telldir(FsContext *ctx, V9fsFidOpenState *fs)
{
return telldir(fs->dir.stream);
}
static bool local_is_mapped_file_metadata(FsContext *fs_ctx, const char *name)
{
return
!strcmp(name, VIRTFS_META_DIR) || !strcmp(name, VIRTFS_META_ROOT_FILE);
}
static struct dirent *local_readdir(FsContext *ctx, V9fsFidOpenState *fs)
{
struct dirent *entry;
again:
entry = readdir(fs->dir.stream);
if (!entry) {
return NULL;
}
if (ctx->export_flags & V9FS_SM_MAPPED) {
entry->d_type = DT_UNKNOWN;
} else if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
if (local_is_mapped_file_metadata(ctx, entry->d_name)) {
/* skip the meta data */
goto again;
}
entry->d_type = DT_UNKNOWN;
}
return entry;
}
static void local_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
{
seekdir(fs->dir.stream, off);
}
static ssize_t local_preadv(FsContext *ctx, V9fsFidOpenState *fs,
const struct iovec *iov,
int iovcnt, off_t offset)
{
#ifdef CONFIG_PREADV
return preadv(fs->fd, iov, iovcnt, offset);
#else
int err = lseek(fs->fd, offset, SEEK_SET);
if (err == -1) {
return err;
} else {
return readv(fs->fd, iov, iovcnt);
}
#endif
}
static ssize_t local_pwritev(FsContext *ctx, V9fsFidOpenState *fs,
const struct iovec *iov,
int iovcnt, off_t offset)
{
ssize_t ret;
#ifdef CONFIG_PREADV
ret = pwritev(fs->fd, iov, iovcnt, offset);
#else
int err = lseek(fs->fd, offset, SEEK_SET);
if (err == -1) {
return err;
} else {
ret = writev(fs->fd, iov, iovcnt);
}
#endif
#ifdef CONFIG_SYNC_FILE_RANGE
if (ret > 0 && ctx->export_flags & V9FS_IMMEDIATE_WRITEOUT) {
/*
* Initiate a writeback. This is not a data integrity sync.
* We want to ensure that we don't leave dirty pages in the cache
* after write when writeout=immediate is sepcified.
*/
sync_file_range(fs->fd, offset, ret,
SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE);
}
#endif
return ret;
}
static int local_chmod(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
{
char *dirpath = g_path_get_dirname(fs_path->data);
char *name = g_path_get_basename(fs_path->data);
int ret = -1;
int dirfd;
dirfd = local_opendir_nofollow(fs_ctx, dirpath);
if (dirfd == -1) {
goto out;
}
if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
ret = local_set_xattrat(dirfd, name, credp);
} else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
ret = local_set_mapped_file_attrat(dirfd, name, credp);
} else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
fs_ctx->export_flags & V9FS_SM_NONE) {
ret = fchmodat_nofollow(dirfd, name, credp->fc_mode);
}
close_preserve_errno(dirfd);
out:
g_free(dirpath);
g_free(name);
return ret;
}
static int local_mknod(FsContext *fs_ctx, V9fsPath *dir_path,
const char *name, FsCred *credp)
{
int err = -1;
int dirfd;
if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
local_is_mapped_file_metadata(fs_ctx, name)) {
errno = EINVAL;
return -1;
}
dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
if (dirfd == -1) {
return -1;
}
if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
err = mknodat(dirfd, name, SM_LOCAL_MODE_BITS | S_IFREG, 0);
if (err == -1) {
goto out;
}
if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
err = local_set_xattrat(dirfd, name, credp);
} else {
err = local_set_mapped_file_attrat(dirfd, name, credp);
}
if (err == -1) {
goto err_end;
}
} else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
fs_ctx->export_flags & V9FS_SM_NONE) {
err = mknodat(dirfd, name, credp->fc_mode, credp->fc_rdev);
if (err == -1) {
goto out;
}
err = local_set_cred_passthrough(fs_ctx, dirfd, name, credp);
if (err == -1) {
goto err_end;
}
}
goto out;
err_end:
unlinkat_preserve_errno(dirfd, name, 0);
out:
close_preserve_errno(dirfd);
return err;
}
static int local_mkdir(FsContext *fs_ctx, V9fsPath *dir_path,
const char *name, FsCred *credp)
{
int err = -1;
int dirfd;
if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
local_is_mapped_file_metadata(fs_ctx, name)) {
errno = EINVAL;
return -1;
}
dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
if (dirfd == -1) {
return -1;
}
if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
err = mkdirat(dirfd, name, SM_LOCAL_DIR_MODE_BITS);
if (err == -1) {
goto out;
}
credp->fc_mode = credp->fc_mode | S_IFDIR;
if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
err = local_set_xattrat(dirfd, name, credp);
} else {
err = local_set_mapped_file_attrat(dirfd, name, credp);
}
if (err == -1) {
goto err_end;
}
} else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
fs_ctx->export_flags & V9FS_SM_NONE) {
err = mkdirat(dirfd, name, credp->fc_mode);
if (err == -1) {
goto out;
}
err = local_set_cred_passthrough(fs_ctx, dirfd, name, credp);
if (err == -1) {
goto err_end;
}
}
goto out;
err_end:
unlinkat_preserve_errno(dirfd, name, AT_REMOVEDIR);
out:
close_preserve_errno(dirfd);
return err;
}
static int local_fstat(FsContext *fs_ctx, int fid_type,
V9fsFidOpenState *fs, struct stat *stbuf)
{
int err, fd;
if (fid_type == P9_FID_DIR) {
fd = dirfd(fs->dir.stream);
} else {
fd = fs->fd;
}
err = fstat(fd, stbuf);
if (err) {
return err;
}
if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
/* Actual credentials are part of extended attrs */
uid_t tmp_uid;
gid_t tmp_gid;
mode_t tmp_mode;
dev_t tmp_dev;
if (fgetxattr(fd, "user.virtfs.uid", &tmp_uid, sizeof(uid_t)) > 0) {
stbuf->st_uid = le32_to_cpu(tmp_uid);
}
if (fgetxattr(fd, "user.virtfs.gid", &tmp_gid, sizeof(gid_t)) > 0) {
stbuf->st_gid = le32_to_cpu(tmp_gid);
}
if (fgetxattr(fd, "user.virtfs.mode", &tmp_mode, sizeof(mode_t)) > 0) {
stbuf->st_mode = le32_to_cpu(tmp_mode);
}
if (fgetxattr(fd, "user.virtfs.rdev", &tmp_dev, sizeof(dev_t)) > 0) {
stbuf->st_rdev = le64_to_cpu(tmp_dev);
}
} else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
errno = EOPNOTSUPP;
return -1;
}
return err;
}
static int local_open2(FsContext *fs_ctx, V9fsPath *dir_path, const char *name,
int flags, FsCred *credp, V9fsFidOpenState *fs)
{
int fd = -1;
int err = -1;
int dirfd;
if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
local_is_mapped_file_metadata(fs_ctx, name)) {
errno = EINVAL;
return -1;
}
/*
* Mark all the open to not follow symlinks
*/
flags |= O_NOFOLLOW;
dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
if (dirfd == -1) {
return -1;
}
/* Determine the security model */
if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
fd = openat_file(dirfd, name, flags, SM_LOCAL_MODE_BITS);
if (fd == -1) {
goto out;
}
credp->fc_mode = credp->fc_mode|S_IFREG;
if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
/* Set cleint credentials in xattr */
err = local_set_xattrat(dirfd, name, credp);
} else {
err = local_set_mapped_file_attrat(dirfd, name, credp);
}
if (err == -1) {
goto err_end;
}
} else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
(fs_ctx->export_flags & V9FS_SM_NONE)) {
fd = openat_file(dirfd, name, flags, credp->fc_mode);
if (fd == -1) {
goto out;
}
err = local_set_cred_passthrough(fs_ctx, dirfd, name, credp);
if (err == -1) {
goto err_end;
}
}
err = fd;
fs->fd = fd;
goto out;
err_end:
unlinkat_preserve_errno(dirfd, name,
flags & O_DIRECTORY ? AT_REMOVEDIR : 0);
close_preserve_errno(fd);
out:
close_preserve_errno(dirfd);
return err;
}
static int local_symlink(FsContext *fs_ctx, const char *oldpath,
V9fsPath *dir_path, const char *name, FsCred *credp)
{
int err = -1;
int dirfd;
if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
local_is_mapped_file_metadata(fs_ctx, name)) {
errno = EINVAL;
return -1;
}
dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
if (dirfd == -1) {
return -1;
}
/* Determine the security model */
if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
int fd;
ssize_t oldpath_size, write_size;
fd = openat_file(dirfd, name, O_CREAT | O_EXCL | O_RDWR,
SM_LOCAL_MODE_BITS);
if (fd == -1) {
goto out;
}
/* Write the oldpath (target) to the file. */
oldpath_size = strlen(oldpath);
do {
write_size = write(fd, (void *)oldpath, oldpath_size);
} while (write_size == -1 && errno == EINTR);
close_preserve_errno(fd);
if (write_size != oldpath_size) {
goto err_end;
}
/* Set cleint credentials in symlink's xattr */
credp->fc_mode = credp->fc_mode | S_IFLNK;
if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
err = local_set_xattrat(dirfd, name, credp);
} else {
err = local_set_mapped_file_attrat(dirfd, name, credp);
}
if (err == -1) {
goto err_end;
}
} else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
fs_ctx->export_flags & V9FS_SM_NONE) {
err = symlinkat(oldpath, dirfd, name);
if (err) {
goto out;
}
err = fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
AT_SYMLINK_NOFOLLOW);
if (err == -1) {
/*
* If we fail to change ownership and if we are
* using security model none. Ignore the error
*/
if ((fs_ctx->export_flags & V9FS_SEC_MASK) != V9FS_SM_NONE) {
goto err_end;
} else {
err = 0;
}
}
}
goto out;
err_end:
unlinkat_preserve_errno(dirfd, name, 0);
out:
close_preserve_errno(dirfd);
return err;
}
static int local_link(FsContext *ctx, V9fsPath *oldpath,
V9fsPath *dirpath, const char *name)
{
char *odirpath = g_path_get_dirname(oldpath->data);
char *oname = g_path_get_basename(oldpath->data);
int ret = -1;
int odirfd, ndirfd;
if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
local_is_mapped_file_metadata(ctx, name)) {
errno = EINVAL;
return -1;
}
odirfd = local_opendir_nofollow(ctx, odirpath);
if (odirfd == -1) {
goto out;
}
ndirfd = local_opendir_nofollow(ctx, dirpath->data);
if (ndirfd == -1) {
close_preserve_errno(odirfd);
goto out;
}
ret = linkat(odirfd, oname, ndirfd, name, 0);
if (ret < 0) {
goto out_close;
}
/* now link the virtfs_metadata files */
if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
int omap_dirfd, nmap_dirfd;
ret = mkdirat(ndirfd, VIRTFS_META_DIR, 0700);
if (ret < 0 && errno != EEXIST) {
goto err_undo_link;
}
omap_dirfd = openat_dir(odirfd, VIRTFS_META_DIR);
if (omap_dirfd == -1) {
goto err;
}
nmap_dirfd = openat_dir(ndirfd, VIRTFS_META_DIR);
if (nmap_dirfd == -1) {
close_preserve_errno(omap_dirfd);
goto err;
}
ret = linkat(omap_dirfd, oname, nmap_dirfd, name, 0);
close_preserve_errno(nmap_dirfd);
close_preserve_errno(omap_dirfd);
if (ret < 0 && errno != ENOENT) {
goto err_undo_link;
}
ret = 0;
}
goto out_close;
err:
ret = -1;
err_undo_link:
unlinkat_preserve_errno(ndirfd, name, 0);
out_close:
close_preserve_errno(ndirfd);
close_preserve_errno(odirfd);
out:
g_free(oname);
g_free(odirpath);
return ret;
}
static int local_truncate(FsContext *ctx, V9fsPath *fs_path, off_t size)
{
int fd, ret;
fd = local_open_nofollow(ctx, fs_path->data, O_WRONLY, 0);
if (fd == -1) {
return -1;
}
ret = ftruncate(fd, size);
close_preserve_errno(fd);
return ret;
}
static int local_chown(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
{
char *dirpath = g_path_get_dirname(fs_path->data);
char *name = g_path_get_basename(fs_path->data);
int ret = -1;
int dirfd;
dirfd = local_opendir_nofollow(fs_ctx, dirpath);
if (dirfd == -1) {
goto out;
}
if ((credp->fc_uid == -1 && credp->fc_gid == -1) ||
(fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
(fs_ctx->export_flags & V9FS_SM_NONE)) {
ret = fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
AT_SYMLINK_NOFOLLOW);
} else if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
ret = local_set_xattrat(dirfd, name, credp);
} else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
ret = local_set_mapped_file_attrat(dirfd, name, credp);
}
close_preserve_errno(dirfd);
out:
g_free(name);
g_free(dirpath);
return ret;
}
static int local_utimensat(FsContext *s, V9fsPath *fs_path,
const struct timespec *buf)
{
char *dirpath = g_path_get_dirname(fs_path->data);
char *name = g_path_get_basename(fs_path->data);
int dirfd, ret = -1;
dirfd = local_opendir_nofollow(s, dirpath);
if (dirfd == -1) {
goto out;
}
ret = utimensat(dirfd, name, buf, AT_SYMLINK_NOFOLLOW);
close_preserve_errno(dirfd);
out:
g_free(dirpath);
g_free(name);
return ret;
}
static int local_unlinkat_common(FsContext *ctx, int dirfd, const char *name,
int flags)
{
int ret = -1;
if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
int map_dirfd;
/* We need to remove the metadata as well:
* - the metadata directory if we're removing a directory
* - the metadata file in the parent's metadata directory
*
* If any of these are missing (ie, ENOENT) then we're probably
* trying to remove something that wasn't created in mapped-file
* mode. We just ignore the error.
*/
if (flags == AT_REMOVEDIR) {
int fd;
fd = openat_dir(dirfd, name);
if (fd == -1) {
goto err_out;
}
ret = unlinkat(fd, VIRTFS_META_DIR, AT_REMOVEDIR);
close_preserve_errno(fd);
if (ret < 0 && errno != ENOENT) {
goto err_out;
}
}
map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
if (map_dirfd != -1) {
ret = unlinkat(map_dirfd, name, 0);
close_preserve_errno(map_dirfd);
if (ret < 0 && errno != ENOENT) {
goto err_out;
}
} else if (errno != ENOENT) {
goto err_out;
}
}
ret = unlinkat(dirfd, name, flags);
err_out:
return ret;
}
static int local_remove(FsContext *ctx, const char *path)
{
struct stat stbuf;
char *dirpath = g_path_get_dirname(path);
char *name = g_path_get_basename(path);
int flags = 0;
int dirfd;
int err = -1;
dirfd = local_opendir_nofollow(ctx, dirpath);
if (dirfd == -1) {
goto out;
}
if (fstatat(dirfd, path, &stbuf, AT_SYMLINK_NOFOLLOW) < 0) {
goto err_out;
}
if (S_ISDIR(stbuf.st_mode)) {
flags |= AT_REMOVEDIR;
}
err = local_unlinkat_common(ctx, dirfd, name, flags);
err_out:
close_preserve_errno(dirfd);
out:
g_free(name);
g_free(dirpath);
return err;
}
static int local_fsync(FsContext *ctx, int fid_type,
V9fsFidOpenState *fs, int datasync)
{
int fd;
if (fid_type == P9_FID_DIR) {
fd = dirfd(fs->dir.stream);
} else {
fd = fs->fd;
}
if (datasync) {
return qemu_fdatasync(fd);
} else {
return fsync(fd);
}
}
static int local_statfs(FsContext *s, V9fsPath *fs_path, struct statfs *stbuf)
{
int fd, ret;
fd = local_open_nofollow(s, fs_path->data, O_RDONLY, 0);
if (fd == -1) {
return -1;
}
ret = fstatfs(fd, stbuf);
close_preserve_errno(fd);
return ret;
}
static ssize_t local_lgetxattr(FsContext *ctx, V9fsPath *fs_path,
const char *name, void *value, size_t size)
{
char *path = fs_path->data;
return v9fs_get_xattr(ctx, path, name, value, size);
}
static ssize_t local_llistxattr(FsContext *ctx, V9fsPath *fs_path,
void *value, size_t size)
{
char *path = fs_path->data;
return v9fs_list_xattr(ctx, path, value, size);
}
static int local_lsetxattr(FsContext *ctx, V9fsPath *fs_path, const char *name,
void *value, size_t size, int flags)
{
char *path = fs_path->data;
return v9fs_set_xattr(ctx, path, name, value, size, flags);
}
static int local_lremovexattr(FsContext *ctx, V9fsPath *fs_path,
const char *name)
{
char *path = fs_path->data;
return v9fs_remove_xattr(ctx, path, name);
}
static int local_name_to_path(FsContext *ctx, V9fsPath *dir_path,
const char *name, V9fsPath *target)
{
if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
local_is_mapped_file_metadata(ctx, name)) {
errno = EINVAL;
return -1;
}
if (dir_path) {
if (!strcmp(name, ".")) {
/* "." relative to "foo/bar" is "foo/bar" */
v9fs_path_copy(target, dir_path);
} else if (!strcmp(name, "..")) {
if (!strcmp(dir_path->data, ".")) {
/* ".." relative to the root is "." */
v9fs_path_sprintf(target, ".");
} else {
char *tmp = g_path_get_dirname(dir_path->data);
/* Symbolic links are resolved by the client. We can assume
* that ".." relative to "foo/bar" is equivalent to "foo"
*/
v9fs_path_sprintf(target, "%s", tmp);
g_free(tmp);
}
} else {
assert(!strchr(name, '/'));
v9fs_path_sprintf(target, "%s/%s", dir_path->data, name);
}
} else if (!strcmp(name, "/") || !strcmp(name, ".") ||
!strcmp(name, "..")) {
/* This is the root fid */
v9fs_path_sprintf(target, ".");
} else {
assert(!strchr(name, '/'));
v9fs_path_sprintf(target, "./%s", name);
}
return 0;
}
static int local_renameat(FsContext *ctx, V9fsPath *olddir,
const char *old_name, V9fsPath *newdir,
const char *new_name)
{
int ret;
int odirfd, ndirfd;
if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
(local_is_mapped_file_metadata(ctx, old_name) ||
local_is_mapped_file_metadata(ctx, new_name))) {
errno = EINVAL;
return -1;
}
odirfd = local_opendir_nofollow(ctx, olddir->data);
if (odirfd == -1) {
return -1;
}
ndirfd = local_opendir_nofollow(ctx, newdir->data);
if (ndirfd == -1) {
close_preserve_errno(odirfd);
return -1;
}
ret = renameat(odirfd, old_name, ndirfd, new_name);
if (ret < 0) {
goto out;
}
if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
int omap_dirfd, nmap_dirfd;
ret = mkdirat(ndirfd, VIRTFS_META_DIR, 0700);
if (ret < 0 && errno != EEXIST) {
goto err_undo_rename;
}
omap_dirfd = openat_dir(odirfd, VIRTFS_META_DIR);
if (omap_dirfd == -1) {
goto err;
}
nmap_dirfd = openat_dir(ndirfd, VIRTFS_META_DIR);
if (nmap_dirfd == -1) {
close_preserve_errno(omap_dirfd);
goto err;
}
/* rename the .virtfs_metadata files */
ret = renameat(omap_dirfd, old_name, nmap_dirfd, new_name);
close_preserve_errno(nmap_dirfd);
close_preserve_errno(omap_dirfd);
if (ret < 0 && errno != ENOENT) {
goto err_undo_rename;
}
ret = 0;
}
goto out;
err:
ret = -1;
err_undo_rename:
renameat_preserve_errno(ndirfd, new_name, odirfd, old_name);
out:
close_preserve_errno(ndirfd);
close_preserve_errno(odirfd);
return ret;
}
static void v9fs_path_init_dirname(V9fsPath *path, const char *str)
{
path->data = g_path_get_dirname(str);
path->size = strlen(path->data) + 1;
}
static int local_rename(FsContext *ctx, const char *oldpath,
const char *newpath)
{
int err;
char *oname = g_path_get_basename(oldpath);
char *nname = g_path_get_basename(newpath);
V9fsPath olddir, newdir;
v9fs_path_init_dirname(&olddir, oldpath);
v9fs_path_init_dirname(&newdir, newpath);
err = local_renameat(ctx, &olddir, oname, &newdir, nname);
v9fs_path_free(&newdir);
v9fs_path_free(&olddir);
g_free(nname);
g_free(oname);
return err;
}
static int local_unlinkat(FsContext *ctx, V9fsPath *dir,
const char *name, int flags)
{
int ret;
int dirfd;
if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
local_is_mapped_file_metadata(ctx, name)) {
errno = EINVAL;
return -1;
}
dirfd = local_opendir_nofollow(ctx, dir->data);
if (dirfd == -1) {
return -1;
}
ret = local_unlinkat_common(ctx, dirfd, name, flags);
close_preserve_errno(dirfd);
return ret;
}
static int local_ioc_getversion(FsContext *ctx, V9fsPath *path,
mode_t st_mode, uint64_t *st_gen)
{
#ifdef FS_IOC_GETVERSION
int err;
V9fsFidOpenState fid_open;
/*
* Do not try to open special files like device nodes, fifos etc
* We can get fd for regular files and directories only
*/
if (!S_ISREG(st_mode) && !S_ISDIR(st_mode)) {
errno = ENOTTY;
return -1;
}
err = local_open(ctx, path, O_RDONLY, &fid_open);
if (err < 0) {
return err;
}
err = ioctl(fid_open.fd, FS_IOC_GETVERSION, st_gen);
local_close(ctx, &fid_open);
return err;
#else
errno = ENOTTY;
return -1;
#endif
}
static int local_init(FsContext *ctx)
{
struct statfs stbuf;
LocalData *data = g_malloc(sizeof(*data));
data->mountfd = open(ctx->fs_root, O_DIRECTORY | O_RDONLY);
if (data->mountfd == -1) {
goto err;
}
#ifdef FS_IOC_GETVERSION
/*
* use ioc_getversion only if the ioctl is definied
*/
if (fstatfs(data->mountfd, &stbuf) < 0) {
close_preserve_errno(data->mountfd);
goto err;
}
switch (stbuf.f_type) {
case EXT2_SUPER_MAGIC:
case BTRFS_SUPER_MAGIC:
case REISERFS_SUPER_MAGIC:
case XFS_SUPER_MAGIC:
ctx->exops.get_st_gen = local_ioc_getversion;
break;
}
#endif
if (ctx->export_flags & V9FS_SM_PASSTHROUGH) {
ctx->xops = passthrough_xattr_ops;
} else if (ctx->export_flags & V9FS_SM_MAPPED) {
ctx->xops = mapped_xattr_ops;
} else if (ctx->export_flags & V9FS_SM_NONE) {
ctx->xops = none_xattr_ops;
} else if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
/*
* xattr operation for mapped-file and passthrough
* remain same.
*/
ctx->xops = passthrough_xattr_ops;
}
ctx->export_flags |= V9FS_PATHNAME_FSCONTEXT;
ctx->private = data;
return 0;
err:
g_free(data);
return -1;
}
static void local_cleanup(FsContext *ctx)
{
LocalData *data = ctx->private;
close(data->mountfd);
g_free(data);
}
static int local_parse_opts(QemuOpts *opts, struct FsDriverEntry *fse)
{
const char *sec_model = qemu_opt_get(opts, "security_model");
const char *path = qemu_opt_get(opts, "path");
Error *err = NULL;
if (!sec_model) {
error_report("Security model not specified, local fs needs security model");
error_printf("valid options are:"
"\tsecurity_model=[passthrough|mapped-xattr|mapped-file|none]\n");
return -1;
}
if (!strcmp(sec_model, "passthrough")) {
fse->export_flags |= V9FS_SM_PASSTHROUGH;
} else if (!strcmp(sec_model, "mapped") ||
!strcmp(sec_model, "mapped-xattr")) {
fse->export_flags |= V9FS_SM_MAPPED;
} else if (!strcmp(sec_model, "none")) {
fse->export_flags |= V9FS_SM_NONE;
} else if (!strcmp(sec_model, "mapped-file")) {
fse->export_flags |= V9FS_SM_MAPPED_FILE;
} else {
error_report("Invalid security model %s specified", sec_model);
error_printf("valid options are:"
"\t[passthrough|mapped-xattr|mapped-file|none]\n");
return -1;
}
if (!path) {
error_report("fsdev: No path specified");
return -1;
}
fsdev_throttle_parse_opts(opts, &fse->fst, &err);
if (err) {
error_reportf_err(err, "Throttle configuration is not valid: ");
return -1;
}
fse->path = g_strdup(path);
return 0;
}
FileOperations local_ops = {
.parse_opts = local_parse_opts,
.init = local_init,
.cleanup = local_cleanup,
.lstat = local_lstat,
.readlink = local_readlink,
.close = local_close,
.closedir = local_closedir,
.open = local_open,
.opendir = local_opendir,
.rewinddir = local_rewinddir,
.telldir = local_telldir,
.readdir = local_readdir,
.seekdir = local_seekdir,
.preadv = local_preadv,
.pwritev = local_pwritev,
.chmod = local_chmod,
.mknod = local_mknod,
.mkdir = local_mkdir,
.fstat = local_fstat,
.open2 = local_open2,
.symlink = local_symlink,
.link = local_link,
.truncate = local_truncate,
.rename = local_rename,
.chown = local_chown,
.utimensat = local_utimensat,
.remove = local_remove,
.fsync = local_fsync,
.statfs = local_statfs,
.lgetxattr = local_lgetxattr,
.llistxattr = local_llistxattr,
.lsetxattr = local_lsetxattr,
.lremovexattr = local_lremovexattr,
.name_to_path = local_name_to_path,
.renameat = local_renameat,
.unlinkat = local_unlinkat,
};
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