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xemu/hw/9pfs/virtio-9p-handle.c
M. Mohan Kumar 2d40564aaa hw/9pfs: Preserve S_ISGID 
In passthrough security model in local fs driver, after a file creation
chown and chmod are done to set the file credentials and mode as requested
by 9p client. But if there was a request to create a file with S_ISGID
bit, doing chown on that file resets the S_ISGID bit. So first call
chown and then invoking chmod with proper mode bit retains the S_ISGID
(if present/requested)

This resulted in LTP mknod02, mknod03, mknod05, open10 test case
failures. This patch fixes this issue.

man 2 chown
When the owner or group of an executable file are changed by an unprivileged
user the S_ISUID  and  S_ISGID mode  bits are cleared.  POSIX does not specify
whether this also should happen when root does the chown(); the Linux behavior
depends on the kernel version.

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2012-01-30 10:54:16 +05:30

700 lines
18 KiB
C
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/*
* Virtio 9p handle callback
*
* Copyright IBM, Corp. 2011
*
* Authors:
* Aneesh Kumar K.V <aneesh.kumar@linux.vnet.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 "hw/virtio.h"
#include "virtio-9p.h"
#include "virtio-9p-xattr.h"
#include <arpa/inet.h>
#include <pwd.h>
#include <grp.h>
#include <sys/socket.h>
#include <sys/un.h>
#include "qemu-xattr.h"
#include <unistd.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
struct handle_data {
int mountfd;
int handle_bytes;
};
static inline int name_to_handle(int dirfd, const char *name,
struct file_handle *fh, int *mnt_id, int flags)
{
return name_to_handle_at(dirfd, name, fh, mnt_id, flags);
}
static inline int open_by_handle(int mountfd, const char *fh, int flags)
{
return open_by_handle_at(mountfd, (struct file_handle *)fh, flags);
}
static int handle_update_file_cred(int dirfd, const char *name, FsCred *credp)
{
int fd, ret;
fd = openat(dirfd, name, O_NONBLOCK | O_NOFOLLOW);
if (fd < 0) {
return fd;
}
ret = fchownat(fd, "", credp->fc_uid, credp->fc_gid, AT_EMPTY_PATH);
if (ret < 0) {
goto err_out;
}
ret = fchmod(fd, credp->fc_mode & 07777);
err_out:
close(fd);
return ret;
}
static int handle_lstat(FsContext *fs_ctx, V9fsPath *fs_path,
struct stat *stbuf)
{
int fd, ret;
struct handle_data *data = (struct handle_data *)fs_ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_PATH);
if (fd < 0) {
return fd;
}
ret = fstatat(fd, "", stbuf, AT_EMPTY_PATH);
close(fd);
return ret;
}
static ssize_t handle_readlink(FsContext *fs_ctx, V9fsPath *fs_path,
char *buf, size_t bufsz)
{
int fd, ret;
struct handle_data *data = (struct handle_data *)fs_ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_PATH);
if (fd < 0) {
return fd;
}
ret = readlinkat(fd, "", buf, bufsz);
close(fd);
return ret;
}
static int handle_close(FsContext *ctx, V9fsFidOpenState *fs)
{
return close(fs->fd);
}
static int handle_closedir(FsContext *ctx, V9fsFidOpenState *fs)
{
return closedir(fs->dir);
}
static int handle_open(FsContext *ctx, V9fsPath *fs_path,
int flags, V9fsFidOpenState *fs)
{
struct handle_data *data = (struct handle_data *)ctx->private;
fs->fd = open_by_handle(data->mountfd, fs_path->data, flags);
return fs->fd;
}
static int handle_opendir(FsContext *ctx,
V9fsPath *fs_path, V9fsFidOpenState *fs)
{
int ret;
ret = handle_open(ctx, fs_path, O_DIRECTORY, fs);
if (ret < 0) {
return -1;
}
fs->dir = fdopendir(ret);
if (!fs->dir) {
return -1;
}
return 0;
}
static void handle_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
{
return rewinddir(fs->dir);
}
static off_t handle_telldir(FsContext *ctx, V9fsFidOpenState *fs)
{
return telldir(fs->dir);
}
static int handle_readdir_r(FsContext *ctx, V9fsFidOpenState *fs,
struct dirent *entry,
struct dirent **result)
{
return readdir_r(fs->dir, entry, result);
}
static void handle_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
{
return seekdir(fs->dir, off);
}
static ssize_t handle_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 handle_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 handle_chmod(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
{
int fd, ret;
struct handle_data *data = (struct handle_data *)fs_ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
if (fd < 0) {
return fd;
}
ret = fchmod(fd, credp->fc_mode);
close(fd);
return ret;
}
static int handle_mknod(FsContext *fs_ctx, V9fsPath *dir_path,
const char *name, FsCred *credp)
{
int dirfd, ret;
struct handle_data *data = (struct handle_data *)fs_ctx->private;
dirfd = open_by_handle(data->mountfd, dir_path->data, O_PATH);
if (dirfd < 0) {
return dirfd;
}
ret = mknodat(dirfd, name, credp->fc_mode, credp->fc_rdev);
if (!ret) {
ret = handle_update_file_cred(dirfd, name, credp);
}
close(dirfd);
return ret;
}
static int handle_mkdir(FsContext *fs_ctx, V9fsPath *dir_path,
const char *name, FsCred *credp)
{
int dirfd, ret;
struct handle_data *data = (struct handle_data *)fs_ctx->private;
dirfd = open_by_handle(data->mountfd, dir_path->data, O_PATH);
if (dirfd < 0) {
return dirfd;
}
ret = mkdirat(dirfd, name, credp->fc_mode);
if (!ret) {
ret = handle_update_file_cred(dirfd, name, credp);
}
close(dirfd);
return ret;
}
static int handle_fstat(FsContext *fs_ctx, int fid_type,
V9fsFidOpenState *fs, struct stat *stbuf)
{
int fd;
if (fid_type == P9_FID_DIR) {
fd = dirfd(fs->dir);
} else {
fd = fs->fd;
}
return fstat(fd, stbuf);
}
static int handle_open2(FsContext *fs_ctx, V9fsPath *dir_path, const char *name,
int flags, FsCred *credp, V9fsFidOpenState *fs)
{
int ret;
int dirfd, fd;
struct handle_data *data = (struct handle_data *)fs_ctx->private;
dirfd = open_by_handle(data->mountfd, dir_path->data, O_PATH);
if (dirfd < 0) {
return dirfd;
}
fd = openat(dirfd, name, flags | O_NOFOLLOW, credp->fc_mode);
if (fd >= 0) {
ret = handle_update_file_cred(dirfd, name, credp);
if (ret < 0) {
close(fd);
fd = ret;
} else {
fs->fd = fd;
}
}
close(dirfd);
return fd;
}
static int handle_symlink(FsContext *fs_ctx, const char *oldpath,
V9fsPath *dir_path, const char *name, FsCred *credp)
{
int fd, dirfd, ret;
struct handle_data *data = (struct handle_data *)fs_ctx->private;
dirfd = open_by_handle(data->mountfd, dir_path->data, O_PATH);
if (dirfd < 0) {
return dirfd;
}
ret = symlinkat(oldpath, dirfd, name);
if (!ret) {
fd = openat(dirfd, name, O_PATH | O_NOFOLLOW);
if (fd < 0) {
ret = fd;
goto err_out;
}
ret = fchownat(fd, "", credp->fc_uid, credp->fc_gid, AT_EMPTY_PATH);
close(fd);
}
err_out:
close(dirfd);
return ret;
}
static int handle_link(FsContext *ctx, V9fsPath *oldpath,
V9fsPath *dirpath, const char *name)
{
int oldfd, newdirfd, ret;
struct handle_data *data = (struct handle_data *)ctx->private;
oldfd = open_by_handle(data->mountfd, oldpath->data, O_PATH);
if (oldfd < 0) {
return oldfd;
}
newdirfd = open_by_handle(data->mountfd, dirpath->data, O_PATH);
if (newdirfd < 0) {
close(oldfd);
return newdirfd;
}
ret = linkat(oldfd, "", newdirfd, name, AT_EMPTY_PATH);
close(newdirfd);
close(oldfd);
return ret;
}
static int handle_truncate(FsContext *ctx, V9fsPath *fs_path, off_t size)
{
int fd, ret;
struct handle_data *data = (struct handle_data *)ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK | O_WRONLY);
if (fd < 0) {
return fd;
}
ret = ftruncate(fd, size);
close(fd);
return ret;
}
static int handle_rename(FsContext *ctx, const char *oldpath,
const char *newpath)
{
errno = EOPNOTSUPP;
return -1;
}
static int handle_chown(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
{
int fd, ret;
struct handle_data *data = (struct handle_data *)fs_ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_PATH);
if (fd < 0) {
return fd;
}
ret = fchownat(fd, "", credp->fc_uid, credp->fc_gid, AT_EMPTY_PATH);
close(fd);
return ret;
}
static int handle_utimensat(FsContext *ctx, V9fsPath *fs_path,
const struct timespec *buf)
{
int ret;
#ifdef CONFIG_UTIMENSAT
int fd;
struct handle_data *data = (struct handle_data *)ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
if (fd < 0) {
return fd;
}
ret = futimens(fd, buf);
close(fd);
#else
ret = -1;
errno = ENOSYS;
#endif
return ret;
}
static int handle_remove(FsContext *ctx, const char *path)
{
errno = EOPNOTSUPP;
return -1;
}
static int handle_fsync(FsContext *ctx, int fid_type,
V9fsFidOpenState *fs, int datasync)
{
int fd;
if (fid_type == P9_FID_DIR) {
fd = dirfd(fs->dir);
} else {
fd = fs->fd;
}
if (datasync) {
return qemu_fdatasync(fd);
} else {
return fsync(fd);
}
}
static int handle_statfs(FsContext *ctx, V9fsPath *fs_path,
struct statfs *stbuf)
{
int fd, ret;
struct handle_data *data = (struct handle_data *)ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
if (fd < 0) {
return fd;
}
ret = fstatfs(fd, stbuf);
close(fd);
return ret;
}
static ssize_t handle_lgetxattr(FsContext *ctx, V9fsPath *fs_path,
const char *name, void *value, size_t size)
{
int fd, ret;
struct handle_data *data = (struct handle_data *)ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
if (fd < 0) {
return fd;
}
ret = fgetxattr(fd, name, value, size);
close(fd);
return ret;
}
static ssize_t handle_llistxattr(FsContext *ctx, V9fsPath *fs_path,
void *value, size_t size)
{
int fd, ret;
struct handle_data *data = (struct handle_data *)ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
if (fd < 0) {
return fd;
}
ret = flistxattr(fd, value, size);
close(fd);
return ret;
}
static int handle_lsetxattr(FsContext *ctx, V9fsPath *fs_path, const char *name,
void *value, size_t size, int flags)
{
int fd, ret;
struct handle_data *data = (struct handle_data *)ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
if (fd < 0) {
return fd;
}
ret = fsetxattr(fd, name, value, size, flags);
close(fd);
return ret;
}
static int handle_lremovexattr(FsContext *ctx, V9fsPath *fs_path,
const char *name)
{
int fd, ret;
struct handle_data *data = (struct handle_data *)ctx->private;
fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
if (fd < 0) {
return fd;
}
ret = fremovexattr(fd, name);
close(fd);
return ret;
}
static int handle_name_to_path(FsContext *ctx, V9fsPath *dir_path,
const char *name, V9fsPath *target)
{
char buffer[PATH_MAX];
struct file_handle *fh;
int dirfd, ret, mnt_id;
struct handle_data *data = (struct handle_data *)ctx->private;
/* "." and ".." are not allowed */
if (!strcmp(name, ".") || !strcmp(name, "..")) {
errno = EINVAL;
return -1;
}
if (dir_path) {
dirfd = open_by_handle(data->mountfd, dir_path->data, O_PATH);
} else {
/* relative to export root */
dirfd = open(rpath(ctx, ".", buffer), O_DIRECTORY);
}
if (dirfd < 0) {
return dirfd;
}
fh = g_malloc(sizeof(struct file_handle) + data->handle_bytes);
fh->handle_bytes = data->handle_bytes;
/* add a "./" at the beginning of the path */
snprintf(buffer, PATH_MAX, "./%s", name);
/* flag = 0 imply don't follow symlink */
ret = name_to_handle(dirfd, buffer, fh, &mnt_id, 0);
if (!ret) {
target->data = (char *)fh;
target->size = sizeof(struct file_handle) + data->handle_bytes;
} else {
g_free(fh);
}
close(dirfd);
return ret;
}
static int handle_renameat(FsContext *ctx, V9fsPath *olddir,
const char *old_name, V9fsPath *newdir,
const char *new_name)
{
int olddirfd, newdirfd, ret;
struct handle_data *data = (struct handle_data *)ctx->private;
olddirfd = open_by_handle(data->mountfd, olddir->data, O_PATH);
if (olddirfd < 0) {
return olddirfd;
}
newdirfd = open_by_handle(data->mountfd, newdir->data, O_PATH);
if (newdirfd < 0) {
close(olddirfd);
return newdirfd;
}
ret = renameat(olddirfd, old_name, newdirfd, new_name);
close(newdirfd);
close(olddirfd);
return ret;
}
static int handle_unlinkat(FsContext *ctx, V9fsPath *dir,
const char *name, int flags)
{
int dirfd, ret;
struct handle_data *data = (struct handle_data *)ctx->private;
int rflags;
dirfd = open_by_handle(data->mountfd, dir->data, O_PATH);
if (dirfd < 0) {
return dirfd;
}
rflags = 0;
if (flags & P9_DOTL_AT_REMOVEDIR) {
rflags |= AT_REMOVEDIR;
}
ret = unlinkat(dirfd, name, rflags);
close(dirfd);
return ret;
}
static int handle_ioc_getversion(FsContext *ctx, V9fsPath *path,
mode_t st_mode, uint64_t *st_gen)
{
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)) {
return 0;
}
err = handle_open(ctx, path, O_RDONLY, &fid_open);
if (err < 0) {
return err;
}
err = ioctl(fid_open.fd, FS_IOC_GETVERSION, st_gen);
handle_close(ctx, &fid_open);
return err;
}
static int handle_init(FsContext *ctx)
{
int ret, mnt_id;
struct statfs stbuf;
struct file_handle fh;
struct handle_data *data = g_malloc(sizeof(struct handle_data));
data->mountfd = open(ctx->fs_root, O_DIRECTORY);
if (data->mountfd < 0) {
ret = data->mountfd;
goto err_out;
}
ret = statfs(ctx->fs_root, &stbuf);
if (!ret) {
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 = handle_ioc_getversion;
break;
}
}
memset(&fh, 0, sizeof(struct file_handle));
ret = name_to_handle(data->mountfd, ".", &fh, &mnt_id, 0);
if (ret && errno == EOVERFLOW) {
data->handle_bytes = fh.handle_bytes;
ctx->private = data;
ret = 0;
goto out;
}
/* we got 0 byte handle ? */
ret = -1;
close(data->mountfd);
err_out:
g_free(data);
out:
return ret;
}
static int handle_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");
if (sec_model) {
fprintf(stderr, "Invalid argument security_model specified with handle fsdriver\n");
return -1;
}
if (!path) {
fprintf(stderr, "fsdev: No path specified.\n");
return -1;
}
fse->path = g_strdup(path);
return 0;
}
FileOperations handle_ops = {
.parse_opts = handle_parse_opts,
.init = handle_init,
.lstat = handle_lstat,
.readlink = handle_readlink,
.close = handle_close,
.closedir = handle_closedir,
.open = handle_open,
.opendir = handle_opendir,
.rewinddir = handle_rewinddir,
.telldir = handle_telldir,
.readdir_r = handle_readdir_r,
.seekdir = handle_seekdir,
.preadv = handle_preadv,
.pwritev = handle_pwritev,
.chmod = handle_chmod,
.mknod = handle_mknod,
.mkdir = handle_mkdir,
.fstat = handle_fstat,
.open2 = handle_open2,
.symlink = handle_symlink,
.link = handle_link,
.truncate = handle_truncate,
.rename = handle_rename,
.chown = handle_chown,
.utimensat = handle_utimensat,
.remove = handle_remove,
.fsync = handle_fsync,
.statfs = handle_statfs,
.lgetxattr = handle_lgetxattr,
.llistxattr = handle_llistxattr,
.lsetxattr = handle_lsetxattr,
.lremovexattr = handle_lremovexattr,
.name_to_path = handle_name_to_path,
.renameat = handle_renameat,
.unlinkat = handle_unlinkat,
};
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