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Re: [Qemu-devel] 9p mapped-* security model infos are architecture-speci
From: |
Aneesh Kumar K.V |
Subject: |
Re: [Qemu-devel] 9p mapped-* security model infos are architecture-specific |
Date: |
Wed, 30 Jul 2014 23:13:37 +0530 |
User-agent: |
Notmuch/0.18.1+51~gbbbdf04 (http://notmuchmail.org) Emacs/24.3.91.1 (x86_64-unknown-linux-gnu) |
"Aneesh Kumar K.V" <address@hidden> writes:
> Michael Tokarev <address@hidden> writes:
>
>> Apparently the the mapped-* security models results in a raw bytes
>> being dumped to host without any architecture normalization (in
>> host byte order). This may even lead to security issues in guest
>> when the same files are served from another host for example.
>>
>> This bug has been initially submitted against debian qemu package, see
>> http://bugs.debian.org/755740
>>
>
> Thanks for reporting the bug. Yes we do have issue with
> mapped-xattr. But mapped-file should be ok. We record the uid/gid as
> string in the file.
What would be the best way to fix this in a backward compatible way ?
Considering most of the users will be little endian host, we could do "always
store in little endian format" which of-course will break big-endian
hosts. We could possibly ask them to update xattr using external tools ?
diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
index 3b0b6a9b1d7d..cd662410420e 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -135,17 +135,17 @@ static int local_lstat(FsContext *fs_ctx, V9fsPath
*fs_path, struct stat *stbuf)
mode_t tmp_mode;
dev_t tmp_dev;
if (getxattr(buffer, "user.virtfs.uid", &tmp_uid, sizeof(uid_t)) > 0) {
- stbuf->st_uid = tmp_uid;
+ stbuf->st_uid = le32_to_cpu(tmp_uid);
}
if (getxattr(buffer, "user.virtfs.gid", &tmp_gid, sizeof(gid_t)) > 0) {
- stbuf->st_gid = tmp_gid;
+ stbuf->st_gid = le32_to_cpu(tmp_gid);
}
if (getxattr(buffer, "user.virtfs.mode",
&tmp_mode, sizeof(mode_t)) > 0) {
- stbuf->st_mode = tmp_mode;
+ stbuf->st_mode = le32_to_cpu(tmp_mode);
}
if (getxattr(buffer, "user.virtfs.rdev", &tmp_dev, sizeof(dev_t)) > 0)
{
- stbuf->st_rdev = tmp_dev;
+ stbuf->st_rdev = le64_to_cpu(tmp_dev);
}
} else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
local_mapped_file_attr(fs_ctx, path, stbuf);
@@ -255,29 +255,29 @@ static int local_set_xattr(const char *path, FsCred
*credp)
int err;
if (credp->fc_uid != -1) {
- err = setxattr(path, "user.virtfs.uid", &credp->fc_uid, sizeof(uid_t),
- 0);
+ uint32_t tmp_uid = cpu_to_le32(credp->fc_uid);
+ err = setxattr(path, "user.virtfs.uid", &tmp_uid, sizeof(uid_t), 0);
if (err) {
return err;
}
}
if (credp->fc_gid != -1) {
- err = setxattr(path, "user.virtfs.gid", &credp->fc_gid, sizeof(gid_t),
- 0);
+ uint32_t tmp_gid = cpu_to_le32(credp->fc_gid);
+ err = setxattr(path, "user.virtfs.gid", &tmp_gid, sizeof(gid_t), 0);
if (err) {
return err;
}
}
if (credp->fc_mode != -1) {
- err = setxattr(path, "user.virtfs.mode", &credp->fc_mode,
- sizeof(mode_t), 0);
+ uint32_t tmp_mode = cpu_to_le32(credp->fc_mode);
+ err = setxattr(path, "user.virtfs.mode", &tmp_mode, sizeof(mode_t), 0);
if (err) {
return err;
}
}
if (credp->fc_rdev != -1) {
- err = setxattr(path, "user.virtfs.rdev", &credp->fc_rdev,
- sizeof(dev_t), 0);
+ uint64_t tmp_rdev = cpu_to_le32(credp->fc_rdev);
+ err = setxattr(path, "user.virtfs.rdev", &tmp_rdev, sizeof(dev_t), 0);
if (err) {
return err;
}
@@ -630,21 +630,17 @@ static int local_fstat(FsContext *fs_ctx, int fid_type,
mode_t tmp_mode;
dev_t tmp_dev;
- if (fgetxattr(fd, "user.virtfs.uid",
- &tmp_uid, sizeof(uid_t)) > 0) {
- stbuf->st_uid = tmp_uid;
+ 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 = tmp_gid;
+ 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 = tmp_mode;
+ 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 = tmp_dev;
+ 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;