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Re: [Qemu-devel] [PATCH v5 1/1] 9pfs: local: Add support for custom fmod
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From: |
Greg Kurz |
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Subject: |
Re: [Qemu-devel] [PATCH v5 1/1] 9pfs: local: Add support for custom fmode/dmode in 9ps mapped security modes |
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Date: |
Tue, 20 Jun 2017 17:25:06 +0200 |
On Tue, 20 Jun 2017 01:37:18 +0200
Tobias Schramm <address@hidden> wrote:
> In mapped security modes, files are created with very restrictive
> permissions (600 for files and 700 for directories). This makes
> file sharing between virtual machines and users on the host rather
> complicated. Imagine eg. a group of users that need to access data
> produced by processes on a virtual machine. Giving those users access
> to the data will be difficult since the group access mode is always 0.
>
> This patch makes the default mode for both files and directories
> configurable. Existing setups that don't know about the new parameters
> keep using the current secure behavior.
>
> Signed-off-by: Tobias Schramm <address@hidden>
> ---
Thanks.
Pushed to https://github.com/gkurz/qemu/commits/9p-next
> v5: Eliminate expandable variables, check mandatory commandline options
> first
> v4: Use OPT_NUMBER for file mode arguments, fix back to front naming,
> fix resource leak and add sanity checking for fmode/dmode arguments
> v3: Use unsigned types for umask
> v2: Adjust patch to QEMU code style
>
> fsdev/file-op-9p.h | 4 ++++
> fsdev/qemu-fsdev-opts.c | 12 ++++++++++++
> hw/9pfs/9p-local.c | 25 +++++++++++++++++++++----
> hw/9pfs/9p.c | 3 +++
> qemu-options.hx | 20 ++++++++++++++++----
> 5 files changed, 56 insertions(+), 8 deletions(-)
>
> diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h
> index 0844a403dc..474c79d003 100644
> --- a/fsdev/file-op-9p.h
> +++ b/fsdev/file-op-9p.h
> @@ -76,6 +76,8 @@ typedef struct FsDriverEntry {
> int export_flags;
> FileOperations *ops;
> FsThrottle fst;
> + mode_t fmode;
> + mode_t dmode;
> } FsDriverEntry;
>
> typedef struct FsContext
> @@ -88,6 +90,8 @@ typedef struct FsContext
> FsThrottle *fst;
> /* fs driver specific data */
> void *private;
> + mode_t fmode;
> + mode_t dmode;
> } FsContext;
>
> typedef struct V9fsPath {
> diff --git a/fsdev/qemu-fsdev-opts.c b/fsdev/qemu-fsdev-opts.c
> index bf5713008a..7c31ffffaf 100644
> --- a/fsdev/qemu-fsdev-opts.c
> +++ b/fsdev/qemu-fsdev-opts.c
> @@ -38,6 +38,12 @@ static QemuOptsList qemu_fsdev_opts = {
> }, {
> .name = "sock_fd",
> .type = QEMU_OPT_NUMBER,
> + }, {
> + .name = "fmode",
> + .type = QEMU_OPT_NUMBER,
> + }, {
> + .name = "dmode",
> + .type = QEMU_OPT_NUMBER,
> },
>
> THROTTLE_OPTS,
> @@ -75,6 +81,12 @@ static QemuOptsList qemu_virtfs_opts = {
> }, {
> .name = "sock_fd",
> .type = QEMU_OPT_NUMBER,
> + }, {
> + .name = "fmode",
> + .type = QEMU_OPT_NUMBER,
> + }, {
> + .name = "dmode",
> + .type = QEMU_OPT_NUMBER,
> },
>
> { /*End of list */ }
> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
> index 1e78b7c9e9..f1ce03b06a 100644
> --- a/hw/9pfs/9p-local.c
> +++ b/hw/9pfs/9p-local.c
> @@ -633,7 +633,7 @@ static int local_mknod(FsContext *fs_ctx, V9fsPath
> *dir_path,
>
> 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);
> + err = mknodat(dirfd, name, fs_ctx->fmode | S_IFREG, 0);
> if (err == -1) {
> goto out;
> }
> @@ -685,7 +685,7 @@ static int local_mkdir(FsContext *fs_ctx, V9fsPath
> *dir_path,
>
> 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);
> + err = mkdirat(dirfd, name, fs_ctx->dmode);
> if (err == -1) {
> goto out;
> }
> @@ -786,7 +786,7 @@ static int local_open2(FsContext *fs_ctx, V9fsPath
> *dir_path, const char *name,
> /* 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);
> + fd = openat_file(dirfd, name, flags, fs_ctx->fmode);
> if (fd == -1) {
> goto out;
> }
> @@ -849,7 +849,7 @@ static int local_symlink(FsContext *fs_ctx, const char
> *oldpath,
> ssize_t oldpath_size, write_size;
>
> fd = openat_file(dirfd, name, O_CREAT | O_EXCL | O_RDWR,
> - SM_LOCAL_MODE_BITS);
> + fs_ctx->fmode);
> if (fd == -1) {
> goto out;
> }
> @@ -1467,6 +1467,23 @@ static int local_parse_opts(QemuOpts *opts, struct
> FsDriverEntry *fse)
> return -1;
> }
>
> + if (fse->export_flags & V9FS_SM_MAPPED ||
> + fse->export_flags & V9FS_SM_MAPPED_FILE) {
> + fse->fmode =
> + qemu_opt_get_number(opts, "fmode", SM_LOCAL_MODE_BITS) & 0777;
> + fse->dmode =
> + qemu_opt_get_number(opts, "dmode", SM_LOCAL_DIR_MODE_BITS) &
> 0777;
> + } else {
> + if (qemu_opt_find(opts, "fmode")) {
> + error_report("fmode is only valid for mapped 9p modes");
> + return -1;
> + }
> + if (qemu_opt_find(opts, "dmode")) {
> + error_report("dmode is only valid for mapped 9p modes");
> + return -1;
> + }
> + }
> +
> fse->path = g_strdup(path);
>
> return 0;
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index 96d2683348..a0ae98f7ca 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -3533,6 +3533,9 @@ int v9fs_device_realize_common(V9fsState *s, Error
> **errp)
>
> s->ops = fse->ops;
>
> + s->ctx.fmode = fse->fmode;
> + s->ctx.dmode = fse->dmode;
> +
> s->fid_list = NULL;
> qemu_co_rwlock_init(&s->rename_lock);
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 30c4f9850f..5999719720 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -847,7 +847,7 @@ ETEXI
>
> DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
> "-fsdev
> fsdriver,id=id[,path=path,][security_model={mapped-xattr|mapped-file|passthrough|none}]\n"
> - " [,writeout=immediate][,readonly][,socket=socket|sock_fd=sock_fd]\n"
> + "
> [,writeout=immediate][,readonly][,socket=socket|sock_fd=sock_fd][,fmode=fmode][,dmode=dmode]\n"
> "
> [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
> "
> [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
> "
> [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
> @@ -857,7 +857,7 @@ DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
>
> STEXI
>
> address@hidden -fsdev
> @var{fsdriver},address@hidden,address@hidden,address@hidden,address@hidden,readonly][,address@hidden|address@hidden
> address@hidden -fsdev
> @var{fsdriver},address@hidden,address@hidden,address@hidden,address@hidden,readonly][,address@hidden|address@hidden,address@hidden,address@hidden
> @findex -fsdev
> Define a new file system device. Valid options are:
> @table @option
> @@ -898,6 +898,12 @@ with virtfs-proxy-helper
> Enables proxy filesystem driver to use passed socket descriptor for
> communicating with virtfs-proxy-helper. Usually a helper like libvirt
> will create socketpair and pass one of the fds as sock_fd
> address@hidden address@hidden
> +Specifies the default mode for newly created files on the host. Works only
> +with security models "mapped-xattr" and "mapped-file".
> address@hidden address@hidden
> +Specifies the default mode for newly created directories on the host. Works
> +only with security models "mapped-xattr" and "mapped-file".
> @end table
>
> -fsdev option is used along with -device driver "virtio-9p-pci".
> @@ -914,12 +920,12 @@ ETEXI
>
> DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
> "-virtfs
> local,path=path,mount_tag=tag,security_model=[mapped-xattr|mapped-file|passthrough|none]\n"
> - "
> [,id=id][,writeout=immediate][,readonly][,socket=socket|sock_fd=sock_fd]\n",
> + "
> [,id=id][,writeout=immediate][,readonly][,socket=socket|sock_fd=sock_fd][,fmode=fmode][,dmode=dmode]\n",
> QEMU_ARCH_ALL)
>
> STEXI
>
> address@hidden -virtfs
> @var{fsdriver}[,address@hidden,address@hidden,address@hidden,address@hidden,readonly][,address@hidden|address@hidden
> address@hidden -virtfs
> @var{fsdriver}[,address@hidden,address@hidden,address@hidden,address@hidden,readonly][,address@hidden|address@hidden,address@hidden,address@hidden
> @findex -virtfs
>
> The general form of a Virtual File system pass-through options are:
> @@ -961,6 +967,12 @@ will create socketpair and pass one of the fds as sock_fd
> @item sock_fd
> Enables proxy filesystem driver to use passed 'sock_fd' as the socket
> descriptor for interfacing with virtfs-proxy-helper
> address@hidden address@hidden
> +Specifies the default mode for newly created files on the host. Works only
> +with security models "mapped-xattr" and "mapped-file".
> address@hidden address@hidden
> +Specifies the default mode for newly created directories on the host. Works
> +only with security models "mapped-xattr" and "mapped-file".
> @end table
> ETEXI
>
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