When truncating files the vfs will verify that the caller is privileged
over the inode. Extend it to handle idmapped mounts. If the inode is
accessed through an idmapped mount it is mapped according to the mount's
user namespace. Afterwards the permissions checks are identical to
non-idmapped mounts. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-16-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
goto close_fail;
}
} else {
goto close_fail;
}
} else {
+ struct user_namespace *mnt_userns;
struct inode *inode;
int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW |
O_LARGEFILE | O_EXCL;
struct inode *inode;
int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW |
O_LARGEFILE | O_EXCL;
* a process dumps core while its cwd is e.g. on a vfat
* filesystem.
*/
* a process dumps core while its cwd is e.g. on a vfat
* filesystem.
*/
- if (!uid_eq(inode->i_uid, current_fsuid()))
+ mnt_userns = file_mnt_user_ns(cprm.file);
+ if (!uid_eq(i_uid_into_mnt(mnt_userns, inode), current_fsuid()))
goto close_fail;
if ((inode->i_mode & 0677) != 0600)
goto close_fail;
if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
goto close_fail;
goto close_fail;
if ((inode->i_mode & 0677) != 0600)
goto close_fail;
if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
goto close_fail;
- if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
+ if (do_truncate(mnt_userns, cprm.file->f_path.dentry,
+ 0, 0, cprm.file))
if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
offset = file->f_op->llseek(file, 0, SEEK_CUR);
if (i_size_read(file->f_mapping->host) < offset)
if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
offset = file->f_op->llseek(file, 0, SEEK_CUR);
if (i_size_read(file->f_mapping->host) < offset)
- do_truncate(file->f_path.dentry, offset, 0, file);
+ do_truncate(file_mnt_user_ns(file), file->f_path.dentry,
+ offset, 0, file);
}
}
EXPORT_SYMBOL(dump_truncate);
}
}
EXPORT_SYMBOL(dump_truncate);
-static int __remove_privs(struct dentry *dentry, int kill)
+static int __remove_privs(struct user_namespace *mnt_userns,
+ struct dentry *dentry, int kill)
* Note we call this on write, so notify_change will not
* encounter any conflicting delegations:
*/
* Note we call this on write, so notify_change will not
* encounter any conflicting delegations:
*/
- return notify_change(&init_user_ns, dentry, &newattrs, NULL);
+ return notify_change(mnt_userns, dentry, &newattrs, NULL);
if (kill < 0)
return kill;
if (kill)
if (kill < 0)
return kill;
if (kill)
- error = __remove_privs(dentry, kill);
+ error = __remove_privs(file_mnt_user_ns(file), dentry, kill);
if (!error)
inode_has_no_xattr(inode);
if (!error)
inode_has_no_xattr(inode);
if (!error)
error = security_path_truncate(path);
if (!error) {
if (!error)
error = security_path_truncate(path);
if (!error) {
- error = do_truncate(path->dentry, 0,
+ error = do_truncate(&init_user_ns, path->dentry, 0,
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
filp);
}
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
filp);
}
-int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
- struct file *filp)
+int do_truncate(struct user_namespace *mnt_userns, struct dentry *dentry,
+ loff_t length, unsigned int time_attrs, struct file *filp)
{
int ret;
struct iattr newattrs;
{
int ret;
struct iattr newattrs;
inode_lock(dentry->d_inode);
/* Note any delegations or leases have already been broken: */
inode_lock(dentry->d_inode);
/* Note any delegations or leases have already been broken: */
- ret = notify_change(&init_user_ns, dentry, &newattrs, NULL);
+ ret = notify_change(mnt_userns, dentry, &newattrs, NULL);
inode_unlock(dentry->d_inode);
return ret;
}
long vfs_truncate(const struct path *path, loff_t length)
{
inode_unlock(dentry->d_inode);
return ret;
}
long vfs_truncate(const struct path *path, loff_t length)
{
+ struct user_namespace *mnt_userns;
struct inode *inode;
long error;
struct inode *inode;
long error;
- error = inode_permission(&init_user_ns, inode, MAY_WRITE);
+ mnt_userns = mnt_user_ns(path->mnt);
+ error = inode_permission(mnt_userns, inode, MAY_WRITE);
if (error)
goto mnt_drop_write_and_out;
if (error)
goto mnt_drop_write_and_out;
if (!error)
error = security_path_truncate(path);
if (!error)
if (!error)
error = security_path_truncate(path);
if (!error)
- error = do_truncate(path->dentry, length, 0, NULL);
+ error = do_truncate(mnt_userns, path->dentry, length, 0, NULL);
put_write_and_out:
put_write_access(inode);
put_write_and_out:
put_write_access(inode);
/* Check IS_APPEND on real upper inode */
if (IS_APPEND(file_inode(f.file)))
goto out_putf;
/* Check IS_APPEND on real upper inode */
if (IS_APPEND(file_inode(f.file)))
goto out_putf;
sb_start_write(inode->i_sb);
error = locks_verify_truncate(inode, f.file, length);
if (!error)
error = security_path_truncate(&f.file->f_path);
if (!error)
sb_start_write(inode->i_sb);
error = locks_verify_truncate(inode, f.file, length);
if (!error)
error = security_path_truncate(&f.file->f_path);
if (!error)
- error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
+ error = do_truncate(file_mnt_user_ns(f.file), dentry, length,
+ ATTR_MTIME | ATTR_CTIME, f.file);
sb_end_write(inode->i_sb);
out_putf:
fdput(f);
sb_end_write(inode->i_sb);
out_putf:
fdput(f);
return mnt_user_ns(file->f_path.mnt);
}
extern long vfs_truncate(const struct path *, loff_t);
return mnt_user_ns(file->f_path.mnt);
}
extern long vfs_truncate(const struct path *, loff_t);
-extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,
- struct file *filp);
+int do_truncate(struct user_namespace *, struct dentry *, loff_t start,
+ unsigned int time_attrs, struct file *filp);
extern int vfs_fallocate(struct file *file, int mode, loff_t offset,
loff_t len);
extern long do_sys_open(int dfd, const char __user *filename, int flags,
extern int vfs_fallocate(struct file *file, int mode, loff_t offset,
loff_t len);
extern long do_sys_open(int dfd, const char __user *filename, int flags,