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Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

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Pull vfs namei updates from Al Viro:

 - make lookup_one_len() safe with parent locked only shared(incoming
   afs series wants that)

 - fix of getname_kernel() regression from 2015 (-stable fodder, that
   one).

* 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  getname_kernel() needs to make sure that ->name != ->iname in long case
  make lookup_one_len() safe to use with directory locked shared
  new helper: __lookup_slow()
  merge common parts of lookup_one_len{,_unlocked} into common helper
This commit is contained in:
Linus Torvalds 2018-04-09 12:48:05 -07:00
commit fd3b36d275
1 changed files with 57 additions and 67 deletions
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124
fs/namei.c
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@ -224,9 +224,10 @@ getname_kernel(const char * filename)
if (len <= EMBEDDED_NAME_MAX) {
result->name = (char *)result->iname;
} else if (len <= PATH_MAX) {
const size_t size = offsetof(struct filename, iname[1]);
struct filename *tmp;
tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
tmp = kmalloc(size, GFP_KERNEL);
if (unlikely(!tmp)) {
__putname(result);
return ERR_PTR(-ENOMEM);
@ -1597,22 +1598,21 @@ static int lookup_fast(struct nameidata *nd,
}
/* Fast lookup failed, do it the slow way */
static struct dentry *lookup_slow(const struct qstr *name,
struct dentry *dir,
unsigned int flags)
static struct dentry *__lookup_slow(const struct qstr *name,
struct dentry *dir,
unsigned int flags)
{
struct dentry *dentry = ERR_PTR(-ENOENT), *old;
struct dentry *dentry, *old;
struct inode *inode = dir->d_inode;
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
inode_lock_shared(inode);
/* Don't go there if it's already dead */
if (unlikely(IS_DEADDIR(inode)))
goto out;
return ERR_PTR(-ENOENT);
again:
dentry = d_alloc_parallel(dir, name, &wq);
if (IS_ERR(dentry))
goto out;
return dentry;
if (unlikely(!d_in_lookup(dentry))) {
if (!(flags & LOOKUP_NO_REVAL)) {
int error = d_revalidate(dentry, flags);
@ -1634,11 +1634,21 @@ again:
dentry = old;
}
}
out:
inode_unlock_shared(inode);
return dentry;
}
static struct dentry *lookup_slow(const struct qstr *name,
struct dentry *dir,
unsigned int flags)
{
struct inode *inode = dir->d_inode;
struct dentry *res;
inode_lock_shared(inode);
res = __lookup_slow(name, dir, flags);
inode_unlock_shared(inode);
return res;
}
static inline int may_lookup(struct nameidata *nd)
{
if (nd->flags & LOOKUP_RCU) {
@ -2421,6 +2431,38 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
}
EXPORT_SYMBOL(vfs_path_lookup);
static int lookup_one_len_common(const char *name, struct dentry *base,
int len, struct qstr *this)
{
this->name = name;
this->len = len;
this->hash = full_name_hash(base, name, len);
if (!len)
return -EACCES;
if (unlikely(name[0] == '.')) {
if (len < 2 || (len == 2 && name[1] == '.'))
return -EACCES;
}
while (len--) {
unsigned int c = *(const unsigned char *)name++;
if (c == '/' || c == '\0')
return -EACCES;
}
/*
* See if the low-level filesystem might want
* to use its own hash..
*/
if (base->d_flags & DCACHE_OP_HASH) {
int err = base->d_op->d_hash(base, this);
if (err < 0)
return err;
}
return inode_permission(base->d_inode, MAY_EXEC);
}
/**
* lookup_one_len - filesystem helper to lookup single pathname component
* @name: pathname component to lookup
@ -2434,43 +2476,18 @@ EXPORT_SYMBOL(vfs_path_lookup);
*/
struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
{
struct dentry *dentry;
struct qstr this;
unsigned int c;
int err;
WARN_ON_ONCE(!inode_is_locked(base->d_inode));
this.name = name;
this.len = len;
this.hash = full_name_hash(base, name, len);
if (!len)
return ERR_PTR(-EACCES);
if (unlikely(name[0] == '.')) {
if (len < 2 || (len == 2 && name[1] == '.'))
return ERR_PTR(-EACCES);
}
while (len--) {
c = *(const unsigned char *)name++;
if (c == '/' || c == '\0')
return ERR_PTR(-EACCES);
}
/*
* See if the low-level filesystem might want
* to use its own hash..
*/
if (base->d_flags & DCACHE_OP_HASH) {
int err = base->d_op->d_hash(base, &this);
if (err < 0)
return ERR_PTR(err);
}
err = inode_permission(base->d_inode, MAY_EXEC);
err = lookup_one_len_common(name, base, len, &this);
if (err)
return ERR_PTR(err);
return __lookup_hash(&this, base, 0);
dentry = lookup_dcache(&this, base, 0);
return dentry ? dentry : __lookup_slow(&this, base, 0);
}
EXPORT_SYMBOL(lookup_one_len);
@ -2490,37 +2507,10 @@ struct dentry *lookup_one_len_unlocked(const char *name,
struct dentry *base, int len)
{
struct qstr this;
unsigned int c;
int err;
struct dentry *ret;
this.name = name;
this.len = len;
this.hash = full_name_hash(base, name, len);
if (!len)
return ERR_PTR(-EACCES);
if (unlikely(name[0] == '.')) {
if (len < 2 || (len == 2 && name[1] == '.'))
return ERR_PTR(-EACCES);
}
while (len--) {
c = *(const unsigned char *)name++;
if (c == '/' || c == '\0')
return ERR_PTR(-EACCES);
}
/*
* See if the low-level filesystem might want
* to use its own hash..
*/
if (base->d_flags & DCACHE_OP_HASH) {
int err = base->d_op->d_hash(base, &this);
if (err < 0)
return ERR_PTR(err);
}
err = inode_permission(base->d_inode, MAY_EXEC);
err = lookup_one_len_common(name, base, len, &this);
if (err)
return ERR_PTR(err);