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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /fs/kernfs/inode.c | |
parent | Initial commit. (diff) | |
download | linux-upstream.tar.xz linux-upstream.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/kernfs/inode.c')
-rw-r--r-- | fs/kernfs/inode.c | 446 |
1 files changed, 446 insertions, 0 deletions
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c new file mode 100644 index 000000000..3d783d80f --- /dev/null +++ b/fs/kernfs/inode.c @@ -0,0 +1,446 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * fs/kernfs/inode.c - kernfs inode implementation + * + * Copyright (c) 2001-3 Patrick Mochel + * Copyright (c) 2007 SUSE Linux Products GmbH + * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> + */ + +#include <linux/pagemap.h> +#include <linux/backing-dev.h> +#include <linux/capability.h> +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/xattr.h> +#include <linux/security.h> + +#include "kernfs-internal.h" + +static const struct inode_operations kernfs_iops = { + .permission = kernfs_iop_permission, + .setattr = kernfs_iop_setattr, + .getattr = kernfs_iop_getattr, + .listxattr = kernfs_iop_listxattr, +}; + +static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc) +{ + static DEFINE_MUTEX(iattr_mutex); + struct kernfs_iattrs *ret; + + mutex_lock(&iattr_mutex); + + if (kn->iattr || !alloc) + goto out_unlock; + + kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL); + if (!kn->iattr) + goto out_unlock; + + /* assign default attributes */ + kn->iattr->ia_uid = GLOBAL_ROOT_UID; + kn->iattr->ia_gid = GLOBAL_ROOT_GID; + + ktime_get_real_ts64(&kn->iattr->ia_atime); + kn->iattr->ia_mtime = kn->iattr->ia_atime; + kn->iattr->ia_ctime = kn->iattr->ia_atime; + + simple_xattrs_init(&kn->iattr->xattrs); + atomic_set(&kn->iattr->nr_user_xattrs, 0); + atomic_set(&kn->iattr->user_xattr_size, 0); +out_unlock: + ret = kn->iattr; + mutex_unlock(&iattr_mutex); + return ret; +} + +static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn) +{ + return __kernfs_iattrs(kn, 1); +} + +static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn) +{ + return __kernfs_iattrs(kn, 0); +} + +int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr) +{ + struct kernfs_iattrs *attrs; + unsigned int ia_valid = iattr->ia_valid; + + attrs = kernfs_iattrs(kn); + if (!attrs) + return -ENOMEM; + + if (ia_valid & ATTR_UID) + attrs->ia_uid = iattr->ia_uid; + if (ia_valid & ATTR_GID) + attrs->ia_gid = iattr->ia_gid; + if (ia_valid & ATTR_ATIME) + attrs->ia_atime = iattr->ia_atime; + if (ia_valid & ATTR_MTIME) + attrs->ia_mtime = iattr->ia_mtime; + if (ia_valid & ATTR_CTIME) + attrs->ia_ctime = iattr->ia_ctime; + if (ia_valid & ATTR_MODE) + kn->mode = iattr->ia_mode; + return 0; +} + +/** + * kernfs_setattr - set iattr on a node + * @kn: target node + * @iattr: iattr to set + * + * Returns 0 on success, -errno on failure. + */ +int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr) +{ + int ret; + struct kernfs_root *root = kernfs_root(kn); + + down_write(&root->kernfs_rwsem); + ret = __kernfs_setattr(kn, iattr); + up_write(&root->kernfs_rwsem); + return ret; +} + +int kernfs_iop_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, + struct iattr *iattr) +{ + struct inode *inode = d_inode(dentry); + struct kernfs_node *kn = inode->i_private; + struct kernfs_root *root; + int error; + + if (!kn) + return -EINVAL; + + root = kernfs_root(kn); + down_write(&root->kernfs_rwsem); + error = setattr_prepare(&init_user_ns, dentry, iattr); + if (error) + goto out; + + error = __kernfs_setattr(kn, iattr); + if (error) + goto out; + + /* this ignores size changes */ + setattr_copy(&init_user_ns, inode, iattr); + +out: + up_write(&root->kernfs_rwsem); + return error; +} + +ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size) +{ + struct kernfs_node *kn = kernfs_dentry_node(dentry); + struct kernfs_iattrs *attrs; + + attrs = kernfs_iattrs(kn); + if (!attrs) + return -ENOMEM; + + return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size); +} + +static inline void set_default_inode_attr(struct inode *inode, umode_t mode) +{ + inode->i_mode = mode; + inode->i_atime = inode->i_mtime = + inode->i_ctime = current_time(inode); +} + +static inline void set_inode_attr(struct inode *inode, + struct kernfs_iattrs *attrs) +{ + inode->i_uid = attrs->ia_uid; + inode->i_gid = attrs->ia_gid; + inode->i_atime = attrs->ia_atime; + inode->i_mtime = attrs->ia_mtime; + inode->i_ctime = attrs->ia_ctime; +} + +static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode) +{ + struct kernfs_iattrs *attrs = kn->iattr; + + inode->i_mode = kn->mode; + if (attrs) + /* + * kernfs_node has non-default attributes get them from + * persistent copy in kernfs_node. + */ + set_inode_attr(inode, attrs); + + if (kernfs_type(kn) == KERNFS_DIR) + set_nlink(inode, kn->dir.subdirs + 2); +} + +int kernfs_iop_getattr(struct user_namespace *mnt_userns, + const struct path *path, struct kstat *stat, + u32 request_mask, unsigned int query_flags) +{ + struct inode *inode = d_inode(path->dentry); + struct kernfs_node *kn = inode->i_private; + struct kernfs_root *root = kernfs_root(kn); + + down_read(&root->kernfs_rwsem); + spin_lock(&inode->i_lock); + kernfs_refresh_inode(kn, inode); + generic_fillattr(&init_user_ns, inode, stat); + spin_unlock(&inode->i_lock); + up_read(&root->kernfs_rwsem); + + return 0; +} + +static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode) +{ + kernfs_get(kn); + inode->i_private = kn; + inode->i_mapping->a_ops = &ram_aops; + inode->i_op = &kernfs_iops; + inode->i_generation = kernfs_gen(kn); + + set_default_inode_attr(inode, kn->mode); + kernfs_refresh_inode(kn, inode); + + /* initialize inode according to type */ + switch (kernfs_type(kn)) { + case KERNFS_DIR: + inode->i_op = &kernfs_dir_iops; + inode->i_fop = &kernfs_dir_fops; + if (kn->flags & KERNFS_EMPTY_DIR) + make_empty_dir_inode(inode); + break; + case KERNFS_FILE: + inode->i_size = kn->attr.size; + inode->i_fop = &kernfs_file_fops; + break; + case KERNFS_LINK: + inode->i_op = &kernfs_symlink_iops; + break; + default: + BUG(); + } + + unlock_new_inode(inode); +} + +/** + * kernfs_get_inode - get inode for kernfs_node + * @sb: super block + * @kn: kernfs_node to allocate inode for + * + * Get inode for @kn. If such inode doesn't exist, a new inode is + * allocated and basics are initialized. New inode is returned + * locked. + * + * LOCKING: + * Kernel thread context (may sleep). + * + * RETURNS: + * Pointer to allocated inode on success, NULL on failure. + */ +struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn) +{ + struct inode *inode; + + inode = iget_locked(sb, kernfs_ino(kn)); + if (inode && (inode->i_state & I_NEW)) + kernfs_init_inode(kn, inode); + + return inode; +} + +/* + * The kernfs_node serves as both an inode and a directory entry for + * kernfs. To prevent the kernfs inode numbers from being freed + * prematurely we take a reference to kernfs_node from the kernfs inode. A + * super_operations.evict_inode() implementation is needed to drop that + * reference upon inode destruction. + */ +void kernfs_evict_inode(struct inode *inode) +{ + struct kernfs_node *kn = inode->i_private; + + truncate_inode_pages_final(&inode->i_data); + clear_inode(inode); + kernfs_put(kn); +} + +int kernfs_iop_permission(struct user_namespace *mnt_userns, + struct inode *inode, int mask) +{ + struct kernfs_node *kn; + struct kernfs_root *root; + int ret; + + if (mask & MAY_NOT_BLOCK) + return -ECHILD; + + kn = inode->i_private; + root = kernfs_root(kn); + + down_read(&root->kernfs_rwsem); + spin_lock(&inode->i_lock); + kernfs_refresh_inode(kn, inode); + ret = generic_permission(&init_user_ns, inode, mask); + spin_unlock(&inode->i_lock); + up_read(&root->kernfs_rwsem); + + return ret; +} + +int kernfs_xattr_get(struct kernfs_node *kn, const char *name, + void *value, size_t size) +{ + struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn); + if (!attrs) + return -ENODATA; + + return simple_xattr_get(&attrs->xattrs, name, value, size); +} + +int kernfs_xattr_set(struct kernfs_node *kn, const char *name, + const void *value, size_t size, int flags) +{ + struct kernfs_iattrs *attrs = kernfs_iattrs(kn); + if (!attrs) + return -ENOMEM; + + return simple_xattr_set(&attrs->xattrs, name, value, size, flags, NULL); +} + +static int kernfs_vfs_xattr_get(const struct xattr_handler *handler, + struct dentry *unused, struct inode *inode, + const char *suffix, void *value, size_t size) +{ + const char *name = xattr_full_name(handler, suffix); + struct kernfs_node *kn = inode->i_private; + + return kernfs_xattr_get(kn, name, value, size); +} + +static int kernfs_vfs_xattr_set(const struct xattr_handler *handler, + struct user_namespace *mnt_userns, + struct dentry *unused, struct inode *inode, + const char *suffix, const void *value, + size_t size, int flags) +{ + const char *name = xattr_full_name(handler, suffix); + struct kernfs_node *kn = inode->i_private; + + return kernfs_xattr_set(kn, name, value, size, flags); +} + +static int kernfs_vfs_user_xattr_add(struct kernfs_node *kn, + const char *full_name, + struct simple_xattrs *xattrs, + const void *value, size_t size, int flags) +{ + atomic_t *sz = &kn->iattr->user_xattr_size; + atomic_t *nr = &kn->iattr->nr_user_xattrs; + ssize_t removed_size; + int ret; + + if (atomic_inc_return(nr) > KERNFS_MAX_USER_XATTRS) { + ret = -ENOSPC; + goto dec_count_out; + } + + if (atomic_add_return(size, sz) > KERNFS_USER_XATTR_SIZE_LIMIT) { + ret = -ENOSPC; + goto dec_size_out; + } + + ret = simple_xattr_set(xattrs, full_name, value, size, flags, + &removed_size); + + if (!ret && removed_size >= 0) + size = removed_size; + else if (!ret) + return 0; +dec_size_out: + atomic_sub(size, sz); +dec_count_out: + atomic_dec(nr); + return ret; +} + +static int kernfs_vfs_user_xattr_rm(struct kernfs_node *kn, + const char *full_name, + struct simple_xattrs *xattrs, + const void *value, size_t size, int flags) +{ + atomic_t *sz = &kn->iattr->user_xattr_size; + atomic_t *nr = &kn->iattr->nr_user_xattrs; + ssize_t removed_size; + int ret; + + ret = simple_xattr_set(xattrs, full_name, value, size, flags, + &removed_size); + + if (removed_size >= 0) { + atomic_sub(removed_size, sz); + atomic_dec(nr); + } + + return ret; +} + +static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler, + struct user_namespace *mnt_userns, + struct dentry *unused, struct inode *inode, + const char *suffix, const void *value, + size_t size, int flags) +{ + const char *full_name = xattr_full_name(handler, suffix); + struct kernfs_node *kn = inode->i_private; + struct kernfs_iattrs *attrs; + + if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR)) + return -EOPNOTSUPP; + + attrs = kernfs_iattrs(kn); + if (!attrs) + return -ENOMEM; + + if (value) + return kernfs_vfs_user_xattr_add(kn, full_name, &attrs->xattrs, + value, size, flags); + else + return kernfs_vfs_user_xattr_rm(kn, full_name, &attrs->xattrs, + value, size, flags); + +} + +static const struct xattr_handler kernfs_trusted_xattr_handler = { + .prefix = XATTR_TRUSTED_PREFIX, + .get = kernfs_vfs_xattr_get, + .set = kernfs_vfs_xattr_set, +}; + +static const struct xattr_handler kernfs_security_xattr_handler = { + .prefix = XATTR_SECURITY_PREFIX, + .get = kernfs_vfs_xattr_get, + .set = kernfs_vfs_xattr_set, +}; + +static const struct xattr_handler kernfs_user_xattr_handler = { + .prefix = XATTR_USER_PREFIX, + .get = kernfs_vfs_xattr_get, + .set = kernfs_vfs_user_xattr_set, +}; + +const struct xattr_handler *kernfs_xattr_handlers[] = { + &kernfs_trusted_xattr_handler, + &kernfs_security_xattr_handler, + &kernfs_user_xattr_handler, + NULL +}; |