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Simplifying ->d_name audits, easy part. 

Turn dentry->d_name into an anon union of const struct qsrt (d_name
 itself) and a writable alias (__d_name).  With constification of some
 struct qstr * arguments of functions that get &dentry->d_name passed
 to them, that ends up with all modifications provably done only in
 fs/dcache.c (and a fairly small part of it).
 
 Any new places doing modifications will be easy to find - grep for
 __d_name will suffice.
 
 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-qstr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull d_name audit update from Al Viro:
 "Simplifying ->d_name audits, easy part.

  Turn dentry->d_name into an anon union of const struct qsrt (d_name
  itself) and a writable alias (__d_name).

  With constification of some struct qstr * arguments of functions that
  get &dentry->d_name passed to them, that ends up with all
  modifications provably done only in fs/dcache.c (and a fairly small
  part of it).

  Any new places doing modifications will be easy to find - grep for
  __d_name will suffice"

* tag 'pull-qstr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  make it easier to catch those who try to modify ->d_name
  generic_ci_validate_strict_name(): constify name argument
  afs_dir_search: constify qstr argument
  afs_edit_dir_{add,remove}(): constify qstr argument
  exfat_find(): constify qstr argument
  security_dentry_init_security(): constify qstr argument
This commit is contained in:
Linus Torvalds 2025-10-03 11:14:02 -07:00
parent 829745b75a 180a9cc3fd
commit 33fc69a05c
12 changed files with 34 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/afs/dir_edit.c
View File

@ -239,7 +239,7 @@ static void afs_edit_init_block(union afs_xdr_dir_block *meta,
* The caller must hold the inode locked. * The caller must hold the inode locked.
*/ */
void afs_edit_dir_add(struct afs_vnode *vnode, void afs_edit_dir_add(struct afs_vnode *vnode,
struct qstr *name, struct afs_fid *new_fid, const struct qstr *name, struct afs_fid *new_fid,
enum afs_edit_dir_reason why) enum afs_edit_dir_reason why)
{ {
union afs_xdr_dir_block *meta, *block; union afs_xdr_dir_block *meta, *block;
@ -391,7 +391,7 @@ void afs_edit_dir_add(struct afs_vnode *vnode,
* The caller must hold the inode locked. * The caller must hold the inode locked.
*/ */
void afs_edit_dir_remove(struct afs_vnode *vnode, void afs_edit_dir_remove(struct afs_vnode *vnode,
struct qstr *name, enum afs_edit_dir_reason why) const struct qstr *name, enum afs_edit_dir_reason why)
{ {
union afs_xdr_dir_block *meta, *block, *pblock; union afs_xdr_dir_block *meta, *block, *pblock;
union afs_xdr_dirent *de, *pde; union afs_xdr_dirent *de, *pde;

2
fs/afs/dir_search.c
View File

@ -188,7 +188,7 @@ int afs_dir_search_bucket(struct afs_dir_iter *iter, const struct qstr *name,
/* /*
* Search the appropriate hash chain in the contents of an AFS directory. * Search the appropriate hash chain in the contents of an AFS directory.
*/ */
int afs_dir_search(struct afs_vnode *dvnode, struct qstr *name, int afs_dir_search(struct afs_vnode *dvnode, const struct qstr *name,
struct afs_fid *_fid, afs_dataversion_t *_dir_version) struct afs_fid *_fid, afs_dataversion_t *_dir_version)
{ {
struct afs_dir_iter iter = { .dvnode = dvnode, }; struct afs_dir_iter iter = { .dvnode = dvnode, };

6
fs/afs/internal.h
View File

@ -1099,9 +1099,9 @@ int afs_single_writepages(struct address_space *mapping,
/* /*
* dir_edit.c * dir_edit.c
*/ */
extern void afs_edit_dir_add(struct afs_vnode *, struct qstr *, struct afs_fid *, extern void afs_edit_dir_add(struct afs_vnode *, const struct qstr *, struct afs_fid *,
enum afs_edit_dir_reason); enum afs_edit_dir_reason);
extern void afs_edit_dir_remove(struct afs_vnode *, struct qstr *, enum afs_edit_dir_reason); extern void afs_edit_dir_remove(struct afs_vnode *, const struct qstr *, enum afs_edit_dir_reason);
void afs_edit_dir_update(struct afs_vnode *vnode, const struct qstr *name, void afs_edit_dir_update(struct afs_vnode *vnode, const struct qstr *name,
struct afs_vnode *new_dvnode, enum afs_edit_dir_reason why); struct afs_vnode *new_dvnode, enum afs_edit_dir_reason why);
void afs_mkdir_init_dir(struct afs_vnode *dvnode, struct afs_vnode *parent_vnode); void afs_mkdir_init_dir(struct afs_vnode *dvnode, struct afs_vnode *parent_vnode);
@ -1114,7 +1114,7 @@ bool afs_dir_init_iter(struct afs_dir_iter *iter, const struct qstr *name);
union afs_xdr_dir_block *afs_dir_find_block(struct afs_dir_iter *iter, size_t block); union afs_xdr_dir_block *afs_dir_find_block(struct afs_dir_iter *iter, size_t block);
int afs_dir_search_bucket(struct afs_dir_iter *iter, const struct qstr *name, int afs_dir_search_bucket(struct afs_dir_iter *iter, const struct qstr *name,
struct afs_fid *_fid); struct afs_fid *_fid);
int afs_dir_search(struct afs_vnode *dvnode, struct qstr *name, int afs_dir_search(struct afs_vnode *dvnode, const struct qstr *name,
struct afs_fid *_fid, afs_dataversion_t *_dir_version); struct afs_fid *_fid, afs_dataversion_t *_dir_version);
/* /*

26
fs/dcache.c
View File

@ -1717,13 +1717,13 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
dname = dentry->d_shortname.string; dname = dentry->d_shortname.string;
} }
dentry->d_name.len = name->len; dentry->__d_name.len = name->len;
dentry->d_name.hash = name->hash; dentry->__d_name.hash = name->hash;
memcpy(dname, name->name, name->len); memcpy(dname, name->name, name->len);
dname[name->len] = 0; dname[name->len] = 0;
/* Make sure we always see the terminating NUL character */ /* Make sure we always see the terminating NUL character */
smp_store_release(&dentry->d_name.name, dname); /* ^^^ */ smp_store_release(&dentry->__d_name.name, dname); /* ^^^ */
dentry->d_flags = 0; dentry->d_flags = 0;
lockref_init(&dentry->d_lockref); lockref_init(&dentry->d_lockref);
@ -2743,15 +2743,15 @@ static void swap_names(struct dentry *dentry, struct dentry *target)
/* /*
* Both external: swap the pointers * Both external: swap the pointers
*/ */
swap(target->d_name.name, dentry->d_name.name); swap(target->__d_name.name, dentry->__d_name.name);
} else { } else {
/* /*
* dentry:internal, target:external. Steal target's * dentry:internal, target:external. Steal target's
* storage and make target internal. * storage and make target internal.
*/ */
dentry->d_name.name = target->d_name.name; dentry->__d_name.name = target->__d_name.name;
target->d_shortname = dentry->d_shortname; target->d_shortname = dentry->d_shortname;
target->d_name.name = target->d_shortname.string; target->__d_name.name = target->d_shortname.string;
} }
} else { } else {
if (unlikely(dname_external(dentry))) { if (unlikely(dname_external(dentry))) {
@ -2759,9 +2759,9 @@ static void swap_names(struct dentry *dentry, struct dentry *target)
* dentry:external, target:internal. Give dentry's * dentry:external, target:internal. Give dentry's
* storage to target and make dentry internal * storage to target and make dentry internal
*/ */
target->d_name.name = dentry->d_name.name; target->__d_name.name = dentry->__d_name.name;
dentry->d_shortname = target->d_shortname; dentry->d_shortname = target->d_shortname;
dentry->d_name.name = dentry->d_shortname.string; dentry->__d_name.name = dentry->d_shortname.string;
} else { } else {
/* /*
* Both are internal. * Both are internal.
@ -2771,7 +2771,7 @@ static void swap_names(struct dentry *dentry, struct dentry *target)
target->d_shortname.words[i]); target->d_shortname.words[i]);
} }
} }
swap(dentry->d_name.hash_len, target->d_name.hash_len); swap(dentry->__d_name.hash_len, target->__d_name.hash_len);
} }
static void copy_name(struct dentry *dentry, struct dentry *target) static void copy_name(struct dentry *dentry, struct dentry *target)
@ -2781,11 +2781,11 @@ static void copy_name(struct dentry *dentry, struct dentry *target)
old_name = external_name(dentry); old_name = external_name(dentry);
if (unlikely(dname_external(target))) { if (unlikely(dname_external(target))) {
atomic_inc(&external_name(target)->count); atomic_inc(&external_name(target)->count);
dentry->d_name = target->d_name; dentry->__d_name = target->__d_name;
} else { } else {
dentry->d_shortname = target->d_shortname; dentry->d_shortname = target->d_shortname;
dentry->d_name.name = dentry->d_shortname.string; dentry->__d_name.name = dentry->d_shortname.string;
dentry->d_name.hash_len = target->d_name.hash_len; dentry->__d_name.hash_len = target->__d_name.hash_len;
} }
if (old_name && likely(atomic_dec_and_test(&old_name->count))) if (old_name && likely(atomic_dec_and_test(&old_name->count)))
kfree_rcu(old_name, head); kfree_rcu(old_name, head);
@ -3134,7 +3134,7 @@ void d_mark_tmpfile(struct file *file, struct inode *inode)
!d_unlinked(dentry)); !d_unlinked(dentry));
spin_lock(&dentry->d_parent->d_lock); spin_lock(&dentry->d_parent->d_lock);
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
dentry->d_name.len = sprintf(dentry->d_shortname.string, "#%llu", dentry->__d_name.len = sprintf(dentry->d_shortname.string, "#%llu",
(unsigned long long)inode->i_ino); (unsigned long long)inode->i_ino);
spin_unlock(&dentry->d_lock); spin_unlock(&dentry->d_lock);
spin_unlock(&dentry->d_parent->d_lock); spin_unlock(&dentry->d_parent->d_lock);

2
fs/exfat/namei.c
View File

@ -587,7 +587,7 @@ static int exfat_create(struct mnt_idmap *idmap, struct inode *dir,
} }
/* lookup a file */ /* lookup a file */
static int exfat_find(struct inode *dir, struct qstr *qname, static int exfat_find(struct inode *dir, const struct qstr *qname,
struct exfat_dir_entry *info) struct exfat_dir_entry *info)
{ {
int ret, dentry, count; int ret, dentry, count;

5
include/linux/dcache.h
View File

@ -95,7 +95,10 @@ struct dentry {
seqcount_spinlock_t d_seq; /* per dentry seqlock */ seqcount_spinlock_t d_seq; /* per dentry seqlock */
struct hlist_bl_node d_hash; /* lookup hash list */ struct hlist_bl_node d_hash; /* lookup hash list */
struct dentry *d_parent; /* parent directory */ struct dentry *d_parent; /* parent directory */
struct qstr d_name; union {
struct qstr __d_name; /* for use ONLY in fs/dcache.c */
const struct qstr d_name;
};
struct inode *d_inode; /* Where the name belongs to - NULL is struct inode *d_inode; /* Where the name belongs to - NULL is
* negative */ * negative */
union shortname_store d_shortname; union shortname_store d_shortname;

6
include/linux/fs.h
View File

@ -3716,7 +3716,8 @@ int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
* happens when a directory is casefolded and the filesystem is strict * happens when a directory is casefolded and the filesystem is strict
* about its encoding. * about its encoding.
*/ */
static inline bool generic_ci_validate_strict_name(struct inode *dir, struct qstr *name) static inline bool generic_ci_validate_strict_name(struct inode *dir,
const struct qstr *name)
{ {
if (!IS_CASEFOLDED(dir) || !sb_has_strict_encoding(dir->i_sb)) if (!IS_CASEFOLDED(dir) || !sb_has_strict_encoding(dir->i_sb))
return true; return true;
@ -3731,7 +3732,8 @@ static inline bool generic_ci_validate_strict_name(struct inode *dir, struct qst
return !utf8_validate(dir->i_sb->s_encoding, name); return !utf8_validate(dir->i_sb->s_encoding, name);
} }
#else #else
static inline bool generic_ci_validate_strict_name(struct inode *dir, struct qstr *name) static inline bool generic_ci_validate_strict_name(struct inode *dir,
const struct qstr *name)
{ {
return true; return true;
} }

2
include/linux/lsm_hook_defs.h
View File

@ -85,7 +85,7 @@ LSM_HOOK(int, -EOPNOTSUPP, dentry_init_security, struct dentry *dentry,
int mode, const struct qstr *name, const char **xattr_name, int mode, const struct qstr *name, const char **xattr_name,
struct lsm_context *cp) struct lsm_context *cp)
LSM_HOOK(int, 0, dentry_create_files_as, struct dentry *dentry, int mode, LSM_HOOK(int, 0, dentry_create_files_as, struct dentry *dentry, int mode,
struct qstr *name, const struct cred *old, struct cred *new) const struct qstr *name, const struct cred *old, struct cred *new)
#ifdef CONFIG_SECURITY_PATH #ifdef CONFIG_SECURITY_PATH
LSM_HOOK(int, 0, path_unlink, const struct path *dir, struct dentry *dentry) LSM_HOOK(int, 0, path_unlink, const struct path *dir, struct dentry *dentry)

4
include/linux/security.h
View File

@ -391,7 +391,7 @@ int security_dentry_init_security(struct dentry *dentry, int mode,
const char **xattr_name, const char **xattr_name,
struct lsm_context *lsmcxt); struct lsm_context *lsmcxt);
int security_dentry_create_files_as(struct dentry *dentry, int mode, int security_dentry_create_files_as(struct dentry *dentry, int mode,
struct qstr *name, const struct qstr *name,
const struct cred *old, const struct cred *old,
struct cred *new); struct cred *new);
int security_path_notify(const struct path *path, u64 mask, int security_path_notify(const struct path *path, u64 mask,
@ -872,7 +872,7 @@ static inline int security_dentry_init_security(struct dentry *dentry,
} }
static inline int security_dentry_create_files_as(struct dentry *dentry, static inline int security_dentry_create_files_as(struct dentry *dentry,
int mode, struct qstr *name, int mode, const struct qstr *name,
const struct cred *old, const struct cred *old,
struct cred *new) struct cred *new)
{ {

2
security/security.c
View File

@ -1814,7 +1814,7 @@ EXPORT_SYMBOL(security_dentry_init_security);
* Return: Returns 0 on success, error on failure. * Return: Returns 0 on success, error on failure.
*/ */
int security_dentry_create_files_as(struct dentry *dentry, int mode, int security_dentry_create_files_as(struct dentry *dentry, int mode,
struct qstr *name, const struct qstr *name,
const struct cred *old, struct cred *new) const struct cred *old, struct cred *new)
{ {
return call_int_hook(dentry_create_files_as, dentry, mode, return call_int_hook(dentry_create_files_as, dentry, mode,

2
security/selinux/hooks.c
View File

@ -2905,7 +2905,7 @@ static int selinux_dentry_init_security(struct dentry *dentry, int mode,
} }
static int selinux_dentry_create_files_as(struct dentry *dentry, int mode, static int selinux_dentry_create_files_as(struct dentry *dentry, int mode,
struct qstr *name, const struct qstr *name,
const struct cred *old, const struct cred *old,
struct cred *new) struct cred *new)
{ {

2
security/smack/smack_lsm.c
View File

@ -4908,7 +4908,7 @@ static int smack_inode_copy_up_xattr(struct dentry *src, const char *name)
} }
static int smack_dentry_create_files_as(struct dentry *dentry, int mode, static int smack_dentry_create_files_as(struct dentry *dentry, int mode,
struct qstr *name, const struct qstr *name,
const struct cred *old, const struct cred *old,
struct cred *new) struct cred *new)
{ {