提交 e9f57ebc 编写于 作者: L Linus Torvalds

Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs updates from Miklos Szeredi:
 "This contains several bug fixes and a new mount option
  'default_permissions' that allows read-only exported NFS
  filesystems to be used as lower layer"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: check dentry positiveness in ovl_cleanup_whiteouts()
  ovl: setattr: check permissions before copy-up
  ovl: root: copy attr
  ovl: move super block magic number to magic.h
  ovl: use a minimal buffer in ovl_copy_xattr
  ovl: allow zero size xattr
  ovl: default permissions
......@@ -22,9 +22,9 @@
int ovl_copy_xattr(struct dentry *old, struct dentry *new)
{
ssize_t list_size, size;
char *buf, *name, *value;
int error;
ssize_t list_size, size, value_size = 0;
char *buf, *name, *value = NULL;
int uninitialized_var(error);
if (!old->d_inode->i_op->getxattr ||
!new->d_inode->i_op->getxattr)
......@@ -41,29 +41,40 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
if (!buf)
return -ENOMEM;
error = -ENOMEM;
value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);
if (!value)
goto out;
list_size = vfs_listxattr(old, buf, list_size);
if (list_size <= 0) {
error = list_size;
goto out_free_value;
goto out;
}
for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);
if (size <= 0) {
retry:
size = vfs_getxattr(old, name, value, value_size);
if (size == -ERANGE)
size = vfs_getxattr(old, name, NULL, 0);
if (size < 0) {
error = size;
goto out_free_value;
break;
}
if (size > value_size) {
void *new;
new = krealloc(value, size, GFP_KERNEL);
if (!new) {
error = -ENOMEM;
break;
}
value = new;
value_size = size;
goto retry;
}
error = vfs_setxattr(new, name, value, size, 0);
if (error)
goto out_free_value;
break;
}
out_free_value:
kfree(value);
out:
kfree(buf);
......
......@@ -42,6 +42,19 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
int err;
struct dentry *upperdentry;
/*
* Check for permissions before trying to copy-up. This is redundant
* since it will be rechecked later by ->setattr() on upper dentry. But
* without this, copy-up can be triggered by just about anybody.
*
* We don't initialize inode->size, which just means that
* inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not
* check for a swapfile (which this won't be anyway).
*/
err = inode_change_ok(dentry->d_inode, attr);
if (err)
return err;
err = ovl_want_write(dentry);
if (err)
goto out;
......@@ -95,6 +108,29 @@ int ovl_permission(struct inode *inode, int mask)
realdentry = ovl_entry_real(oe, &is_upper);
if (ovl_is_default_permissions(inode)) {
struct kstat stat;
struct path realpath = { .dentry = realdentry };
if (mask & MAY_NOT_BLOCK)
return -ECHILD;
realpath.mnt = ovl_entry_mnt_real(oe, inode, is_upper);
err = vfs_getattr(&realpath, &stat);
if (err)
return err;
if ((stat.mode ^ inode->i_mode) & S_IFMT)
return -ESTALE;
inode->i_mode = stat.mode;
inode->i_uid = stat.uid;
inode->i_gid = stat.gid;
return generic_permission(inode, mask);
}
/* Careful in RCU walk mode */
realinode = ACCESS_ONCE(realdentry->d_inode);
if (!realinode) {
......
......@@ -142,7 +142,10 @@ struct dentry *ovl_dentry_upper(struct dentry *dentry);
struct dentry *ovl_dentry_lower(struct dentry *dentry);
struct dentry *ovl_dentry_real(struct dentry *dentry);
struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper);
struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
bool is_upper);
struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry);
bool ovl_is_default_permissions(struct inode *inode);
void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache);
struct dentry *ovl_workdir(struct dentry *dentry);
int ovl_want_write(struct dentry *dentry);
......
......@@ -571,6 +571,7 @@ void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
(int) PTR_ERR(dentry));
continue;
}
if (dentry->d_inode)
ovl_cleanup(upper->d_inode, dentry);
dput(dentry);
}
......
......@@ -9,6 +9,7 @@
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include <linux/mount.h>
......@@ -24,12 +25,11 @@ MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
MODULE_DESCRIPTION("Overlay filesystem");
MODULE_LICENSE("GPL");
#define OVERLAYFS_SUPER_MAGIC 0x794c7630
struct ovl_config {
char *lowerdir;
char *upperdir;
char *workdir;
bool default_permissions;
};
/* private information held for overlayfs's superblock */
......@@ -154,6 +154,18 @@ struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper)
return realdentry;
}
struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
bool is_upper)
{
if (is_upper) {
struct ovl_fs *ofs = inode->i_sb->s_fs_info;
return ofs->upper_mnt;
} else {
return oe->numlower ? oe->lowerstack[0].mnt : NULL;
}
}
struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
......@@ -161,6 +173,13 @@ struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
return oe->cache;
}
bool ovl_is_default_permissions(struct inode *inode)
{
struct ovl_fs *ofs = inode->i_sb->s_fs_info;
return ofs->config.default_permissions;
}
void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
{
struct ovl_entry *oe = dentry->d_fsdata;
......@@ -594,6 +613,8 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
seq_show_option(m, "upperdir", ufs->config.upperdir);
seq_show_option(m, "workdir", ufs->config.workdir);
}
if (ufs->config.default_permissions)
seq_puts(m, ",default_permissions");
return 0;
}
......@@ -618,6 +639,7 @@ enum {
OPT_LOWERDIR,
OPT_UPPERDIR,
OPT_WORKDIR,
OPT_DEFAULT_PERMISSIONS,
OPT_ERR,
};
......@@ -625,6 +647,7 @@ static const match_table_t ovl_tokens = {
{OPT_LOWERDIR, "lowerdir=%s"},
{OPT_UPPERDIR, "upperdir=%s"},
{OPT_WORKDIR, "workdir=%s"},
{OPT_DEFAULT_PERMISSIONS, "default_permissions"},
{OPT_ERR, NULL}
};
......@@ -685,6 +708,10 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
return -ENOMEM;
break;
case OPT_DEFAULT_PERMISSIONS:
config->default_permissions = true;
break;
default:
pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
return -EINVAL;
......@@ -910,6 +937,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
}
sb->s_stack_depth = 0;
sb->s_maxbytes = MAX_LFS_FILESIZE;
if (ufs->config.upperdir) {
if (!ufs->config.workdir) {
pr_err("overlayfs: missing 'workdir'\n");
......@@ -1053,6 +1081,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
root_dentry->d_fsdata = oe;
ovl_copyattr(ovl_dentry_real(root_dentry)->d_inode,
root_dentry->d_inode);
sb->s_magic = OVERLAYFS_SUPER_MAGIC;
sb->s_op = &ovl_super_operations;
sb->s_root = root_dentry;
......
......@@ -31,6 +31,7 @@
#define PSTOREFS_MAGIC 0x6165676C
#define EFIVARFS_MAGIC 0xde5e81e4
#define HOSTFS_SUPER_MAGIC 0x00c0ffee
#define OVERLAYFS_SUPER_MAGIC 0x794c7630
#define MINIX_SUPER_MAGIC 0x137F /* minix v1 fs, 14 char names */
#define MINIX_SUPER_MAGIC2 0x138F /* minix v1 fs, 30 char names */
......
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