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9pfs: local: keep a file descriptor on the shared folder 

This patch opens the shared folder and caches the file descriptor, so that
it can be used to do symlink-safe path walk.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Greg Kurz 2017-02-26 23:42:10 +01:00
parent 6482a96163
commit 0e35a37829
1 changed files with 28 additions and 2 deletions
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30
hw/9pfs/9p-local.c
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@ -14,6 +14,7 @@
#include "qemu/osdep.h"
#include "9p.h"
#include "9p-xattr.h"
#include "9p-util.h"
#include "fsdev/qemu-fsdev.h" /* local_ops */
#include <arpa/inet.h>
#include <pwd.h>
@ -43,6 +44,10 @@
#define BTRFS_SUPER_MAGIC 0x9123683E
#endif
typedef struct {
int mountfd;
} LocalData;
#define VIRTFS_META_DIR ".virtfs_metadata"
static char *local_mapped_attr_path(FsContext *ctx, const char *path)
@ -1176,13 +1181,20 @@ static int local_ioc_getversion(FsContext *ctx, V9fsPath *path,
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 (statfs(ctx->fs_root, &stbuf) < 0) {
return -1;
if (fstatfs(data->mountfd, &stbuf) < 0) {
close_preserve_errno(data->mountfd);
goto err;
}
switch (stbuf.f_type) {
case EXT2_SUPER_MAGIC:
@ -1209,7 +1221,20 @@ static int local_init(FsContext *ctx)
}
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)
@ -1252,6 +1277,7 @@ static int local_parse_opts(QemuOpts *opts, struct FsDriverEntry *fse)
FileOperations local_ops = {
.parse_opts = local_parse_opts,
.init = local_init,
.cleanup = local_cleanup,
.lstat = local_lstat,
.readlink = local_readlink,
.close = local_close,