diff options
Diffstat (limited to 'fs/sdcardfs/inode.c')
| -rw-r--r-- | fs/sdcardfs/inode.c | 914 |
1 files changed, 914 insertions, 0 deletions
diff --git a/fs/sdcardfs/inode.c b/fs/sdcardfs/inode.c new file mode 100644 index 000000000000..39b8b2b9af87 --- /dev/null +++ b/fs/sdcardfs/inode.c @@ -0,0 +1,914 @@ +/* + * fs/sdcardfs/inode.c + * + * Copyright (c) 2013 Samsung Electronics Co. Ltd + * Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun, + * Sunghwan Yun, Sungjong Seo + * + * This program has been developed as a stackable file system based on + * the WrapFS which written by + * + * Copyright (c) 1998-2011 Erez Zadok + * Copyright (c) 2009 Shrikar Archak + * Copyright (c) 2003-2011 Stony Brook University + * Copyright (c) 2003-2011 The Research Foundation of SUNY + * + * This file is dual licensed. It may be redistributed and/or modified + * under the terms of the Apache 2.0 License OR version 2 of the GNU + * General Public License. + */ + +#include "sdcardfs.h" +#include <linux/fs_struct.h> +#include <linux/ratelimit.h> + +/* Do not directly use this function. Use OVERRIDE_CRED() instead. */ +const struct cred *override_fsids(struct sdcardfs_sb_info *sbi, + struct sdcardfs_inode_data *data) +{ + struct cred *cred; + const struct cred *old_cred; + uid_t uid; + + cred = prepare_creds(); + if (!cred) + return NULL; + + if (data->under_obb) + uid = AID_MEDIA_OBB; + else + uid = multiuser_get_uid(data->userid, sbi->options.fs_low_uid); + cred->fsuid = make_kuid(&init_user_ns, uid); + cred->fsgid = make_kgid(&init_user_ns, sbi->options.fs_low_gid); + + old_cred = override_creds(cred); + + return old_cred; +} + +/* Do not directly use this function, use REVERT_CRED() instead. */ +void revert_fsids(const struct cred *old_cred) +{ + const struct cred *cur_cred; + + cur_cred = current->cred; + revert_creds(old_cred); + put_cred(cur_cred); +} + +static int sdcardfs_create(struct inode *dir, struct dentry *dentry, + umode_t mode, bool want_excl) +{ + int err; + struct dentry *lower_dentry; + struct vfsmount *lower_dentry_mnt; + struct dentry *lower_parent_dentry = NULL; + struct path lower_path; + const struct cred *saved_cred = NULL; + struct fs_struct *saved_fs; + struct fs_struct *copied_fs; + + if (!check_caller_access_to_name(dir, &dentry->d_name)) { + err = -EACCES; + goto out_eacces; + } + + /* save current_cred and override it */ + OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir)); + + sdcardfs_get_lower_path(dentry, &lower_path); + lower_dentry = lower_path.dentry; + lower_dentry_mnt = lower_path.mnt; + lower_parent_dentry = lock_parent(lower_dentry); + + /* set last 16bytes of mode field to 0664 */ + mode = (mode & S_IFMT) | 00664; + + /* temporarily change umask for lower fs write */ + saved_fs = current->fs; + copied_fs = copy_fs_struct(current->fs); + if (!copied_fs) { + err = -ENOMEM; + goto out_unlock; + } + current->fs = copied_fs; + current->fs->umask = 0; + err = vfs_create2(lower_dentry_mnt, lower_parent_dentry->d_inode, lower_dentry, mode, want_excl); + if (err) + goto out; + + err = sdcardfs_interpose(dentry, dir->i_sb, &lower_path, + SDCARDFS_I(dir)->data->userid); + if (err) + goto out; + fsstack_copy_attr_times(dir, sdcardfs_lower_inode(dir)); + fsstack_copy_inode_size(dir, lower_parent_dentry->d_inode); + fixup_lower_ownership(dentry, dentry->d_name.name); + +out: + current->fs = saved_fs; + free_fs_struct(copied_fs); +out_unlock: + unlock_dir(lower_parent_dentry); + sdcardfs_put_lower_path(dentry, &lower_path); + REVERT_CRED(saved_cred); +out_eacces: + return err; +} + +#if 0 +static int sdcardfs_link(struct dentry *old_dentry, struct inode *dir, + struct dentry *new_dentry) +{ + struct dentry *lower_old_dentry; + struct dentry *lower_new_dentry; + struct dentry *lower_dir_dentry; + u64 file_size_save; + int err; + struct path lower_old_path, lower_new_path; + + OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb)); + + file_size_save = i_size_read(old_dentry->d_inode); + sdcardfs_get_lower_path(old_dentry, &lower_old_path); + sdcardfs_get_lower_path(new_dentry, &lower_new_path); + lower_old_dentry = lower_old_path.dentry; + lower_new_dentry = lower_new_path.dentry; + lower_dir_dentry = lock_parent(lower_new_dentry); + + err = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode, + lower_new_dentry, NULL); + if (err || !lower_new_dentry->d_inode) + goto out; + + err = sdcardfs_interpose(new_dentry, dir->i_sb, &lower_new_path); + if (err) + goto out; + fsstack_copy_attr_times(dir, lower_new_dentry->d_inode); + fsstack_copy_inode_size(dir, lower_new_dentry->d_inode); + set_nlink(old_dentry->d_inode, + sdcardfs_lower_inode(old_dentry->d_inode)->i_nlink); + i_size_write(new_dentry->d_inode, file_size_save); +out: + unlock_dir(lower_dir_dentry); + sdcardfs_put_lower_path(old_dentry, &lower_old_path); + sdcardfs_put_lower_path(new_dentry, &lower_new_path); + REVERT_CRED(); + return err; +} +#endif + +static int sdcardfs_unlink(struct inode *dir, struct dentry *dentry) +{ + int err; + struct dentry *lower_dentry; + struct vfsmount *lower_mnt; + struct inode *lower_dir_inode = sdcardfs_lower_inode(dir); + struct dentry *lower_dir_dentry; + struct path lower_path; + const struct cred *saved_cred = NULL; + + if (!check_caller_access_to_name(dir, &dentry->d_name)) { + err = -EACCES; + goto out_eacces; + } + + /* save current_cred and override it */ + OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir)); + + sdcardfs_get_lower_path(dentry, &lower_path); + lower_dentry = lower_path.dentry; + lower_mnt = lower_path.mnt; + dget(lower_dentry); + lower_dir_dentry = lock_parent(lower_dentry); + + err = vfs_unlink2(lower_mnt, lower_dir_inode, lower_dentry, NULL); + + /* + * Note: unlinking on top of NFS can cause silly-renamed files. + * Trying to delete such files results in EBUSY from NFS + * below. Silly-renamed files will get deleted by NFS later on, so + * we just need to detect them here and treat such EBUSY errors as + * if the upper file was successfully deleted. + */ + if (err == -EBUSY && lower_dentry->d_flags & DCACHE_NFSFS_RENAMED) + err = 0; + if (err) + goto out; + fsstack_copy_attr_times(dir, lower_dir_inode); + fsstack_copy_inode_size(dir, lower_dir_inode); + set_nlink(dentry->d_inode, + sdcardfs_lower_inode(dentry->d_inode)->i_nlink); + dentry->d_inode->i_ctime = dir->i_ctime; + d_drop(dentry); /* this is needed, else LTP fails (VFS won't do it) */ +out: + unlock_dir(lower_dir_dentry); + dput(lower_dentry); + sdcardfs_put_lower_path(dentry, &lower_path); + REVERT_CRED(saved_cred); +out_eacces: + return err; +} + +#if 0 +static int sdcardfs_symlink(struct inode *dir, struct dentry *dentry, + const char *symname) +{ + int err; + struct dentry *lower_dentry; + struct dentry *lower_parent_dentry = NULL; + struct path lower_path; + + OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb)); + + sdcardfs_get_lower_path(dentry, &lower_path); + lower_dentry = lower_path.dentry; + lower_parent_dentry = lock_parent(lower_dentry); + + err = vfs_symlink(lower_parent_dentry->d_inode, lower_dentry, symname); + if (err) + goto out; + err = sdcardfs_interpose(dentry, dir->i_sb, &lower_path); + if (err) + goto out; + fsstack_copy_attr_times(dir, sdcardfs_lower_inode(dir)); + fsstack_copy_inode_size(dir, lower_parent_dentry->d_inode); + +out: + unlock_dir(lower_parent_dentry); + sdcardfs_put_lower_path(dentry, &lower_path); + REVERT_CRED(); + return err; +} +#endif + +static int touch(char *abs_path, mode_t mode) +{ + struct file *filp = filp_open(abs_path, O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW, mode); + + if (IS_ERR(filp)) { + if (PTR_ERR(filp) == -EEXIST) { + return 0; + } else { + pr_err("sdcardfs: failed to open(%s): %ld\n", + abs_path, PTR_ERR(filp)); + return PTR_ERR(filp); + } + } + filp_close(filp, current->files); + return 0; +} + +static int sdcardfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) +{ + int err; + int make_nomedia_in_obb = 0; + struct dentry *lower_dentry; + struct vfsmount *lower_mnt; + struct dentry *lower_parent_dentry = NULL; + struct path lower_path; + struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb); + const struct cred *saved_cred = NULL; + struct sdcardfs_inode_data *pd = SDCARDFS_I(dir)->data; + int touch_err = 0; + struct fs_struct *saved_fs; + struct fs_struct *copied_fs; + struct qstr q_obb = QSTR_LITERAL("obb"); + struct qstr q_data = QSTR_LITERAL("data"); + + if (!check_caller_access_to_name(dir, &dentry->d_name)) { + err = -EACCES; + goto out_eacces; + } + + /* save current_cred and override it */ + OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir)); + + /* check disk space */ + if (!check_min_free_space(dentry, 0, 1)) { + pr_err("sdcardfs: No minimum free space.\n"); + err = -ENOSPC; + goto out_revert; + } + + /* the lower_dentry is negative here */ + sdcardfs_get_lower_path(dentry, &lower_path); + lower_dentry = lower_path.dentry; + lower_mnt = lower_path.mnt; + lower_parent_dentry = lock_parent(lower_dentry); + + /* set last 16bytes of mode field to 0775 */ + mode = (mode & S_IFMT) | 00775; + + /* temporarily change umask for lower fs write */ + saved_fs = current->fs; + copied_fs = copy_fs_struct(current->fs); + if (!copied_fs) { + err = -ENOMEM; + unlock_dir(lower_parent_dentry); + goto out_unlock; + } + current->fs = copied_fs; + current->fs->umask = 0; + err = vfs_mkdir2(lower_mnt, lower_parent_dentry->d_inode, lower_dentry, mode); + + if (err) { + unlock_dir(lower_parent_dentry); + goto out; + } + + /* if it is a local obb dentry, setup it with the base obbpath */ + if (need_graft_path(dentry)) { + + err = setup_obb_dentry(dentry, &lower_path); + if (err) { + /* if the sbi->obbpath is not available, the lower_path won't be + * changed by setup_obb_dentry() but the lower path is saved to + * its orig_path. this dentry will be revalidated later. + * but now, the lower_path should be NULL + */ + sdcardfs_put_reset_lower_path(dentry); + + /* the newly created lower path which saved to its orig_path or + * the lower_path is the base obbpath. + * therefore, an additional path_get is required + */ + path_get(&lower_path); + } else + make_nomedia_in_obb = 1; + } + + err = sdcardfs_interpose(dentry, dir->i_sb, &lower_path, pd->userid); + if (err) { + unlock_dir(lower_parent_dentry); + goto out; + } + + fsstack_copy_attr_times(dir, sdcardfs_lower_inode(dir)); + fsstack_copy_inode_size(dir, lower_parent_dentry->d_inode); + /* update number of links on parent directory */ + set_nlink(dir, sdcardfs_lower_inode(dir)->i_nlink); + fixup_lower_ownership(dentry, dentry->d_name.name); + unlock_dir(lower_parent_dentry); + if ((!sbi->options.multiuser) && (qstr_case_eq(&dentry->d_name, &q_obb)) + && (pd->perm == PERM_ANDROID) && (pd->userid == 0)) + make_nomedia_in_obb = 1; + + /* When creating /Android/data and /Android/obb, mark them as .nomedia */ + if (make_nomedia_in_obb || + ((pd->perm == PERM_ANDROID) + && (qstr_case_eq(&dentry->d_name, &q_data)))) { + REVERT_CRED(saved_cred); + OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dentry->d_inode)); + set_fs_pwd(current->fs, &lower_path); + touch_err = touch(".nomedia", 0664); + if (touch_err) { + pr_err("sdcardfs: failed to create .nomedia in %s: %d\n", + lower_path.dentry->d_name.name, touch_err); + goto out; + } + } +out: + current->fs = saved_fs; + free_fs_struct(copied_fs); +out_unlock: + sdcardfs_put_lower_path(dentry, &lower_path); +out_revert: + REVERT_CRED(saved_cred); +out_eacces: + return err; +} + +static int sdcardfs_rmdir(struct inode *dir, struct dentry *dentry) +{ + struct dentry *lower_dentry; + struct dentry *lower_dir_dentry; + struct vfsmount *lower_mnt; + int err; + struct path lower_path; + const struct cred *saved_cred = NULL; + + if (!check_caller_access_to_name(dir, &dentry->d_name)) { + err = -EACCES; + goto out_eacces; + } + + /* save current_cred and override it */ + OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir)); + + /* sdcardfs_get_real_lower(): in case of remove an user's obb dentry + * the dentry on the original path should be deleted. + */ + sdcardfs_get_real_lower(dentry, &lower_path); + + lower_dentry = lower_path.dentry; + lower_mnt = lower_path.mnt; + lower_dir_dentry = lock_parent(lower_dentry); + + err = vfs_rmdir2(lower_mnt, lower_dir_dentry->d_inode, lower_dentry); + if (err) + goto out; + + d_drop(dentry); /* drop our dentry on success (why not VFS's job?) */ + if (dentry->d_inode) + clear_nlink(dentry->d_inode); + fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode); + fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode); + set_nlink(dir, lower_dir_dentry->d_inode->i_nlink); + +out: + unlock_dir(lower_dir_dentry); + sdcardfs_put_real_lower(dentry, &lower_path); + REVERT_CRED(saved_cred); +out_eacces: + return err; +} + +#if 0 +static int sdcardfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, + dev_t dev) +{ + int err; + struct dentry *lower_dentry; + struct dentry *lower_parent_dentry = NULL; + struct path lower_path; + + OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb)); + + sdcardfs_get_lower_path(dentry, &lower_path); + lower_dentry = lower_path.dentry; + lower_parent_dentry = lock_parent(lower_dentry); + + err = vfs_mknod(lower_parent_dentry->d_inode, lower_dentry, mode, dev); + if (err) + goto out; + + err = sdcardfs_interpose(dentry, dir->i_sb, &lower_path); + if (err) + goto out; + fsstack_copy_attr_times(dir, sdcardfs_lower_inode(dir)); + fsstack_copy_inode_size(dir, lower_parent_dentry->d_inode); + +out: + unlock_dir(lower_parent_dentry); + sdcardfs_put_lower_path(dentry, &lower_path); + REVERT_CRED(); + return err; +} +#endif + +/* + * The locking rules in sdcardfs_rename are complex. We could use a simpler + * superblock-level name-space lock for renames and copy-ups. + */ +static int sdcardfs_rename(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry) +{ + int err = 0; + struct dentry *lower_old_dentry = NULL; + struct dentry *lower_new_dentry = NULL; + struct dentry *lower_old_dir_dentry = NULL; + struct dentry *lower_new_dir_dentry = NULL; + struct vfsmount *lower_mnt = NULL; + struct dentry *trap = NULL; + struct path lower_old_path, lower_new_path; + const struct cred *saved_cred = NULL; + + if (!check_caller_access_to_name(old_dir, &old_dentry->d_name) || + !check_caller_access_to_name(new_dir, &new_dentry->d_name)) { + err = -EACCES; + goto out_eacces; + } + + /* save current_cred and override it */ + OVERRIDE_CRED(SDCARDFS_SB(old_dir->i_sb), saved_cred, SDCARDFS_I(new_dir)); + + sdcardfs_get_real_lower(old_dentry, &lower_old_path); + sdcardfs_get_lower_path(new_dentry, &lower_new_path); + lower_old_dentry = lower_old_path.dentry; + lower_new_dentry = lower_new_path.dentry; + lower_mnt = lower_old_path.mnt; + lower_old_dir_dentry = dget_parent(lower_old_dentry); + lower_new_dir_dentry = dget_parent(lower_new_dentry); + + trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry); + /* source should not be ancestor of target */ + if (trap == lower_old_dentry) { + err = -EINVAL; + goto out; + } + /* target should not be ancestor of source */ + if (trap == lower_new_dentry) { + err = -ENOTEMPTY; + goto out; + } + + err = vfs_rename2(lower_mnt, + lower_old_dir_dentry->d_inode, lower_old_dentry, + lower_new_dir_dentry->d_inode, lower_new_dentry, + NULL, 0); + if (err) + goto out; + + /* Copy attrs from lower dir, but i_uid/i_gid */ + sdcardfs_copy_and_fix_attrs(new_dir, lower_new_dir_dentry->d_inode); + fsstack_copy_inode_size(new_dir, lower_new_dir_dentry->d_inode); + + if (new_dir != old_dir) { + sdcardfs_copy_and_fix_attrs(old_dir, lower_old_dir_dentry->d_inode); + fsstack_copy_inode_size(old_dir, lower_old_dir_dentry->d_inode); + } + get_derived_permission_new(new_dentry->d_parent, old_dentry, &new_dentry->d_name); + fixup_tmp_permissions(old_dentry->d_inode); + fixup_lower_ownership(old_dentry, new_dentry->d_name.name); + d_invalidate(old_dentry); /* Can't fixup ownership recursively :( */ +out: + unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry); + dput(lower_old_dir_dentry); + dput(lower_new_dir_dentry); + sdcardfs_put_real_lower(old_dentry, &lower_old_path); + sdcardfs_put_lower_path(new_dentry, &lower_new_path); + REVERT_CRED(saved_cred); +out_eacces: + return err; +} + +#if 0 +static int sdcardfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz) +{ + int err; + struct dentry *lower_dentry; + struct path lower_path; + /* XXX readlink does not requires overriding credential */ + + sdcardfs_get_lower_path(dentry, &lower_path); + lower_dentry = lower_path.dentry; + if (!lower_dentry->d_inode->i_op || + !lower_dentry->d_inode->i_op->readlink) { + err = -EINVAL; + goto out; + } + + err = lower_dentry->d_inode->i_op->readlink(lower_dentry, + buf, bufsiz); + if (err < 0) + goto out; + fsstack_copy_attr_atime(dentry->d_inode, lower_dentry->d_inode); + +out: + sdcardfs_put_lower_path(dentry, &lower_path); + return err; +} +#endif + +#if 0 +static void *sdcardfs_follow_link(struct dentry *dentry, struct nameidata *nd) +{ + char *buf; + int len = PAGE_SIZE, err; + mm_segment_t old_fs; + + /* This is freed by the put_link method assuming a successful call. */ + buf = kmalloc(len, GFP_KERNEL); + if (!buf) { + buf = ERR_PTR(-ENOMEM); + goto out; + } + + /* read the symlink, and then we will follow it */ + old_fs = get_fs(); + set_fs(KERNEL_DS); + err = sdcardfs_readlink(dentry, buf, len); + set_fs(old_fs); + if (err < 0) { + kfree(buf); + buf = ERR_PTR(err); + } else { + buf[err] = '\0'; + } +out: + nd_set_link(nd, buf); + return NULL; +} +#endif + +static int sdcardfs_permission_wrn(struct inode *inode, int mask) +{ + WARN_RATELIMIT(1, "sdcardfs does not support permission. Use permission2.\n"); + return -EINVAL; +} + +void copy_attrs(struct inode *dest, const struct inode *src) +{ + dest->i_mode = src->i_mode; + dest->i_uid = src->i_uid; + dest->i_gid = src->i_gid; + dest->i_rdev = src->i_rdev; + dest->i_atime = src->i_atime; + dest->i_mtime = src->i_mtime; + dest->i_ctime = src->i_ctime; + dest->i_blkbits = src->i_blkbits; + dest->i_flags = src->i_flags; +#ifdef CONFIG_FS_POSIX_ACL + dest->i_acl = src->i_acl; +#endif +#ifdef CONFIG_SECURITY + dest->i_security = src->i_security; +#endif +} + +static int sdcardfs_permission(struct vfsmount *mnt, struct inode *inode, int mask) +{ + int err; + struct inode tmp; + struct sdcardfs_inode_data *top = top_data_get(SDCARDFS_I(inode)); + + if (!top) + return -EINVAL; + + /* + * Permission check on sdcardfs inode. + * Calling process should have AID_SDCARD_RW permission + * Since generic_permission only needs i_mode, i_uid, + * i_gid, and i_sb, we can create a fake inode to pass + * this information down in. + * + * The underlying code may attempt to take locks in some + * cases for features we're not using, but if that changes, + * locks must be dealt with to avoid undefined behavior. + */ + copy_attrs(&tmp, inode); + tmp.i_uid = make_kuid(&init_user_ns, top->d_uid); + tmp.i_gid = make_kgid(&init_user_ns, get_gid(mnt, top)); + tmp.i_mode = (inode->i_mode & S_IFMT) + | get_mode(mnt, SDCARDFS_I(inode), top); + data_put(top); + tmp.i_sb = inode->i_sb; + if (IS_POSIXACL(inode)) + pr_warn("%s: This may be undefined behavior...\n", __func__); + err = generic_permission(&tmp, mask); + /* XXX + * Original sdcardfs code calls inode_permission(lower_inode,.. ) + * for checking inode permission. But doing such things here seems + * duplicated work, because the functions called after this func, + * such as vfs_create, vfs_unlink, vfs_rename, and etc, + * does exactly same thing, i.e., they calls inode_permission(). + * So we just let they do the things. + * If there are any security hole, just uncomment following if block. + */ +#if 0 + if (!err) { + /* + * Permission check on lower_inode(=EXT4). + * we check it with AID_MEDIA_RW permission + */ + struct inode *lower_inode; + + OVERRIDE_CRED(SDCARDFS_SB(inode->sb)); + + lower_inode = sdcardfs_lower_inode(inode); + err = inode_permission(lower_inode, mask); + + REVERT_CRED(); + } +#endif + return err; + +} + +static int sdcardfs_setattr_wrn(struct dentry *dentry, struct iattr *ia) +{ + WARN_RATELIMIT(1, "sdcardfs does not support setattr. User setattr2.\n"); + return -EINVAL; +} + +static int sdcardfs_setattr(struct vfsmount *mnt, struct dentry *dentry, struct iattr *ia) +{ + int err; + struct dentry *lower_dentry; + struct vfsmount *lower_mnt; + struct inode *inode; + struct inode *lower_inode; + struct path lower_path; + struct iattr lower_ia; + struct dentry *parent; + struct inode tmp; + struct sdcardfs_inode_data *top; + const struct cred *saved_cred = NULL; + + inode = dentry->d_inode; + top = top_data_get(SDCARDFS_I(inode)); + + if (!top) + return -EINVAL; + + /* + * Permission check on sdcardfs inode. + * Calling process should have AID_SDCARD_RW permission + * Since generic_permission only needs i_mode, i_uid, + * i_gid, and i_sb, we can create a fake inode to pass + * this information down in. + * + * The underlying code may attempt to take locks in some + * cases for features we're not using, but if that changes, + * locks must be dealt with to avoid undefined behavior. + * + */ + copy_attrs(&tmp, inode); + tmp.i_uid = make_kuid(&init_user_ns, top->d_uid); + tmp.i_gid = make_kgid(&init_user_ns, get_gid(mnt, top)); + tmp.i_mode = (inode->i_mode & S_IFMT) + | get_mode(mnt, SDCARDFS_I(inode), top); + tmp.i_size = i_size_read(inode); + data_put(top); + tmp.i_sb = inode->i_sb; + + /* + * Check if user has permission to change inode. We don't check if + * this user can change the lower inode: that should happen when + * calling notify_change on the lower inode. + */ + /* prepare our own lower struct iattr (with the lower file) */ + memcpy(&lower_ia, ia, sizeof(lower_ia)); + /* Allow touch updating timestamps. A previous permission check ensures + * we have write access. Changes to mode, owner, and group are ignored + */ + ia->ia_valid |= ATTR_FORCE; + err = inode_change_ok(&tmp, ia); + + if (!err) { + /* check the Android group ID */ + parent = dget_parent(dentry); + if (!check_caller_access_to_name(parent->d_inode, &dentry->d_name)) + err = -EACCES; + dput(parent); + } + + if (err) + goto out_err; + + /* save current_cred and override it */ + OVERRIDE_CRED(SDCARDFS_SB(dentry->d_sb), saved_cred, SDCARDFS_I(inode)); + + sdcardfs_get_lower_path(dentry, &lower_path); + lower_dentry = lower_path.dentry; + lower_mnt = lower_path.mnt; + lower_inode = sdcardfs_lower_inode(inode); + + if (ia->ia_valid & ATTR_FILE) + lower_ia.ia_file = sdcardfs_lower_file(ia->ia_file); + + lower_ia.ia_valid &= ~(ATTR_UID | ATTR_GID | ATTR_MODE); + + /* + * If shrinking, first truncate upper level to cancel writing dirty + * pages beyond the new eof; and also if its' maxbytes is more + * limiting (fail with -EFBIG before making any change to the lower + * level). There is no need to vmtruncate the upper level + * afterwards in the other cases: we fsstack_copy_inode_size from + * the lower level. + */ + if (current->mm) + down_write(¤t->mm->mmap_sem); + if (ia->ia_valid & ATTR_SIZE) { + err = inode_newsize_ok(&tmp, ia->ia_size); + if (err) { + if (current->mm) + up_write(¤t->mm->mmap_sem); + goto out; + } + truncate_setsize(inode, ia->ia_size); + } + + /* + * mode change is for clearing setuid/setgid bits. Allow lower fs + * to interpret this in its own way. + */ + if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID)) + lower_ia.ia_valid &= ~ATTR_MODE; + + /* notify the (possibly copied-up) lower inode */ + /* + * Note: we use lower_dentry->d_inode, because lower_inode may be + * unlinked (no inode->i_sb and i_ino==0. This happens if someone + * tries to open(), unlink(), then ftruncate() a file. + */ + mutex_lock(&lower_dentry->d_inode->i_mutex); + err = notify_change2(lower_mnt, lower_dentry, &lower_ia, /* note: lower_ia */ + NULL); + mutex_unlock(&lower_dentry->d_inode->i_mutex); + if (current->mm) + up_write(¤t->mm->mmap_sem); + if (err) + goto out; + + /* get attributes from the lower inode and update derived permissions */ + sdcardfs_copy_and_fix_attrs(inode, lower_inode); + + /* + * Not running fsstack_copy_inode_size(inode, lower_inode), because + * VFS should update our inode size, and notify_change on + * lower_inode should update its size. + */ + +out: + sdcardfs_put_lower_path(dentry, &lower_path); + REVERT_CRED(saved_cred); +out_err: + return err; +} + +static int sdcardfs_fillattr(struct vfsmount *mnt, + struct inode *inode, struct kstat *stat) +{ + struct sdcardfs_inode_info *info = SDCARDFS_I(inode); + struct sdcardfs_inode_data *top = top_data_get(info); + + if (!top) + return -EINVAL; + + stat->dev = inode->i_sb->s_dev; + stat->ino = inode->i_ino; + stat->mode = (inode->i_mode & S_IFMT) | get_mode(mnt, info, top); + stat->nlink = inode->i_nlink; + stat->uid = make_kuid(&init_user_ns, top->d_uid); + stat->gid = make_kgid(&init_user_ns, get_gid(mnt, top)); + stat->rdev = inode->i_rdev; + stat->size = i_size_read(inode); + stat->atime = inode->i_atime; + stat->mtime = inode->i_mtime; + stat->ctime = inode->i_ctime; + stat->blksize = (1 << inode->i_blkbits); + stat->blocks = inode->i_blocks; + data_put(top); + return 0; +} + +static int sdcardfs_getattr(struct vfsmount *mnt, struct dentry *dentry, + struct kstat *stat) +{ + struct kstat lower_stat; + struct path lower_path; + struct dentry *parent; + int err; + + parent = dget_parent(dentry); + if (!check_caller_access_to_name(parent->d_inode, &dentry->d_name)) { + dput(parent); + return -EACCES; + } + dput(parent); + + sdcardfs_get_lower_path(dentry, &lower_path); + err = vfs_getattr(&lower_path, &lower_stat); + if (err) + goto out; + sdcardfs_copy_and_fix_attrs(dentry->d_inode, + lower_path.dentry->d_inode); + err = sdcardfs_fillattr(mnt, dentry->d_inode, stat); + stat->blocks = lower_stat.blocks; +out: + sdcardfs_put_lower_path(dentry, &lower_path); + return err; +} + +const struct inode_operations sdcardfs_symlink_iops = { + .permission2 = sdcardfs_permission, + .setattr2 = sdcardfs_setattr, + /* XXX Following operations are implemented, + * but FUSE(sdcard) or FAT does not support them + * These methods are *NOT* perfectly tested. + .readlink = sdcardfs_readlink, + .follow_link = sdcardfs_follow_link, + .put_link = kfree_put_link, + */ +}; + +const struct inode_operations sdcardfs_dir_iops = { + .create = sdcardfs_create, + .lookup = sdcardfs_lookup, + .permission = sdcardfs_permission_wrn, + .permission2 = sdcardfs_permission, + .unlink = sdcardfs_unlink, + .mkdir = sdcardfs_mkdir, + .rmdir = sdcardfs_rmdir, + .rename = sdcardfs_rename, + .setattr = sdcardfs_setattr_wrn, + .setattr2 = sdcardfs_setattr, + .getattr = sdcardfs_getattr, + /* XXX Following operations are implemented, + * but FUSE(sdcard) or FAT does not support them + * These methods are *NOT* perfectly tested. + .symlink = sdcardfs_symlink, + .link = sdcardfs_link, + .mknod = sdcardfs_mknod, + */ +}; + +const struct inode_operations sdcardfs_main_iops = { + .permission = sdcardfs_permission_wrn, + .permission2 = sdcardfs_permission, + .setattr = sdcardfs_setattr_wrn, + .setattr2 = sdcardfs_setattr, + .getattr = sdcardfs_getattr, +}; |