9pfs: local: Add support for custom fmode/dmode in 9ps mapped security modes
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 <tobleminer@gmail.com>
Signed-off-by: Greg Kurz <groug@kaod.org>
diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h
index 0844a40..474c79d 100644
--- a/fsdev/file-op-9p.h
+++ b/fsdev/file-op-9p.h
@@ -76,6 +76,8 @@
int export_flags;
FileOperations *ops;
FsThrottle fst;
+ mode_t fmode;
+ mode_t dmode;
} FsDriverEntry;
typedef struct FsContext
@@ -88,6 +90,8 @@
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 bf57130..7c31fff 100644
--- a/fsdev/qemu-fsdev-opts.c
+++ b/fsdev/qemu-fsdev-opts.c
@@ -38,6 +38,12 @@
}, {
.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 @@
}, {
.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 83952ef..6e478f4 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -633,7 +633,7 @@
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 @@
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 @@
/* 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 @@
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 @@
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 96d2683..a0ae98f 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -3533,6 +3533,9 @@
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 896ff17..297bd8a 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1010,7 +1010,7 @@
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"
@@ -1020,7 +1020,7 @@
STEXI
-@item -fsdev @var{fsdriver},id=@var{id},path=@var{path},[security_model=@var{security_model}][,writeout=@var{writeout}][,readonly][,socket=@var{socket}|sock_fd=@var{sock_fd}]
+@item -fsdev @var{fsdriver},id=@var{id},path=@var{path},[security_model=@var{security_model}][,writeout=@var{writeout}][,readonly][,socket=@var{socket}|sock_fd=@var{sock_fd}][,fmode=@var{fmode}][,dmode=@var{dmode}]
@findex -fsdev
Define a new file system device. Valid options are:
@table @option
@@ -1061,6 +1061,12 @@
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
+@item fmode=@var{fmode}
+Specifies the default mode for newly created files on the host. Works only
+with security models "mapped-xattr" and "mapped-file".
+@item dmode=@var{dmode}
+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".
@@ -1077,12 +1083,12 @@
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
-@item -virtfs @var{fsdriver}[,path=@var{path}],mount_tag=@var{mount_tag}[,security_model=@var{security_model}][,writeout=@var{writeout}][,readonly][,socket=@var{socket}|sock_fd=@var{sock_fd}]
+@item -virtfs @var{fsdriver}[,path=@var{path}],mount_tag=@var{mount_tag}[,security_model=@var{security_model}][,writeout=@var{writeout}][,readonly][,socket=@var{socket}|sock_fd=@var{sock_fd}][,fmode=@var{fmode}][,dmode=@var{dmode}]
@findex -virtfs
The general form of a Virtual File system pass-through options are:
@@ -1124,6 +1130,12 @@
@item sock_fd
Enables proxy filesystem driver to use passed 'sock_fd' as the socket
descriptor for interfacing with virtfs-proxy-helper
+@item fmode=@var{fmode}
+Specifies the default mode for newly created files on the host. Works only
+with security models "mapped-xattr" and "mapped-file".
+@item dmode=@var{dmode}
+Specifies the default mode for newly created directories on the host. Works
+only with security models "mapped-xattr" and "mapped-file".
@end table
ETEXI
