This function is similar but much simpler to sysfs_get_dentry
returns a sysfs dentry if one curently exists.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Benjamin Thery <benjamin.thery@bull.net>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c |   39 +++++++++++++++++++++++++++++++++++++++
 1 files changed, 39 insertions(+), 0 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 69c40ed..df9934a 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -764,6 +764,45 @@ void sysfs_remove_dir(struct kobject * kobj)
 	__sysfs_remove_dir(sd);
 }
 
+/**
+ *	__sysfs_get_dentry - get dentry for the given sysfs_dirent
+ *	@sb: superblock of the dentry to return
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Get dentry for @sd.  Only return a dentry if one currently
+ *	exists.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ *
+ *	RETURNS:
+ *	Pointer to found dentry on success, NULL on failure.
+ */
+static struct dentry *__sysfs_get_dentry(struct super_block *sb,
+					 struct sysfs_dirent *sd)
+{
+	struct inode *inode;
+	struct dentry *dentry = NULL;
+
+	inode = ilookup5_nowait(sysfs_sb, sd->s_ino, sysfs_ilookup_test, sd);
+	if (inode && !(inode->i_state & I_NEW)) {
+		struct dentry *alias;
+		spin_lock(&dcache_lock);
+		list_for_each_entry(alias, &inode->i_dentry, d_alias) {
+			if (!IS_ROOT(alias) && d_unhashed(alias))
+				continue;
+			if (alias->d_sb != sb)
+				continue;
+			dentry = alias;
+			dget_locked(dentry);
+			break;
+		}
+		spin_unlock(&dcache_lock);
+	}
+	iput(inode);
+	return dentry;
+}
+
 int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 {
 	struct sysfs_dirent *sd = kobj->sd;
-- 
1.5.3.rc6.17.g1911

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This patch modifies the sysfs_rename_dir and sysfs_move_dir routines
to support multiple sysfs dentry tries rooted in different
sysfs superblocks.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Benjamin Thery <benjamin.thery@bull.net>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c |  193 +++++++++++++++++++++++++++++++++++++++-----------------
 1 files changed, 136 insertions(+), 57 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index df9934a..b2d92ea 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -803,43 +803,113 @@ static struct dentry *__sysfs_get_dentry(struct super_block *sb,
 	return dentry;
 }
 
+struct sysfs_rename_struct {
+	struct list_head list;
+	struct dentry *old_dentry;
+	struct dentry *new_dentry;
+	struct dentry *old_parent;
+	struct dentry *new_parent;
+};
+
+static void post_rename(struct list_head *head)
+{
+	struct sysfs_rename_struct *srs;
+	while (!list_empty(head)) {
+		srs = list_entry(head->next, struct sysfs_rename_struct, list);
+		dput(srs->old_dentry);
+		dput(srs->new_dentry);
+		dput(srs->old_parent);
+		dput(srs->new_parent);
+		list_del(&srs->list);
+		kfree(srs);
+	}
+}
+
+static int prep_rename(struct list_head *head,
+	struct sysfs_dirent *sd, struct sysfs_dirent *new_parent_sd,
+	const char *name)
+{
+	struct sysfs_rename_struct *srs;
+	struct super_block *sb;
+	struct dentry *dentry;
+	int error;
+
+	list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) {
+		dentry = sysfs_get_dentry(sb, sd);
+		if (dentry == ERR_PTR(-EXDEV))
+			continue;
+		if (IS_ERR(dentry)) {
+			error = PTR_ERR(dentry);
+			goto err_out;
+		}
+
+		srs = kzalloc(sizeof(*srs), GFP_KERNEL);
+		if (!srs) {
+			error = -ENOMEM;
+			dput(dentry);
+			goto err_out;
+		}
+
+		INIT_LIST_HEAD(&srs->list);
+		list_add(head, &srs->list);
+		srs->old_dentry = dentry;
+		srs->old_parent = dget(dentry->d_parent);
+
+		dentry = sysfs_get_dentry(sb, new_parent_sd);
+		if (IS_ERR(dentry)) {
+			error = PTR_ERR(dentry);
+			goto err_out;
+		}
+		srs->new_parent = dentry;
+
+		error = -ENOMEM;
+		dentry = d_alloc_name(srs->new_parent, name);
+		if (!dentry)
+			goto err_out;
+		srs->new_dentry = dentry;
+	}
+	return 0;
+
+err_out:
+	post_rename(head);
+	return error;
+}
+
 int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 {
 	struct sysfs_dirent *sd = kobj->sd;
-	struct dentry *parent = NULL;
-	struct dentry *old_dentry = NULL, *new_dentry = NULL;
+	struct list_head todo;
+	struct sysfs_rename_struct *srs;
+	struct inode *parent_inode = NULL;
 	const char *dup_name = NULL;
 	int error;
 
+	INIT_LIST_HEAD(&todo);
 	mutex_lock(&sysfs_rename_mutex);
 
 	error = 0;
 	if (strcmp(sd->s_name, new_name) == 0)
 		goto out;	/* nothing to rename */
 
-	/* get the original dentry */
-	old_dentry = sysfs_get_dentry(sysfs_sb, sd);
-	if (IS_ERR(old_dentry)) {
-		error = PTR_ERR(old_dentry);
-		old_dentry = NULL;
-		goto out;
-	}
+	sysfs_grab_supers();
+	error = prep_rename(&todo, sd, sd->s_parent, new_name);
+	if (error)
+		goto out_release;
 
-	parent = old_dentry->d_parent;
+	error = -ENOMEM;
+	mutex_lock(&sysfs_mutex);
+	parent_inode = sysfs_get_inode(sd->s_parent);
+	mutex_unlock(&sysfs_mutex);
+	if (!parent_inode)
+		goto out_release;
 
-	/* lock parent and get dentry for new name */
-	mutex_lock(&parent->d_inode->i_mutex);
+	mutex_lock(&parent_inode->i_mutex);
 	mutex_lock(&sysfs_mutex);
 
 	error = -EEXIST;
 	if (sysfs_find_dirent(sd->s_parent, new_name))
 		goto out_unlock;
 
-	error = -ENOMEM;
-	new_dentry = d_alloc_name(parent, new_name);
-	if (!new_dentry)
-		goto out_unlock;
-
 	/* rename sysfs_dirent */
 	error = -ENOMEM;
 	new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
@@ -850,17 +920,21 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 	sd->s_name = new_name;
 
 	/* rename */
-	d_add(new_dentry, NULL);
-	d_move(old_dentry, new_dentry);
+	list_for_each_entry(srs, &todo, list) {
+		d_add(srs->new_dentry, NULL);
+		d_move(srs->old_dentry, srs->new_dentry);
+	}
 
 	error = 0;
- out_unlock:
+out_unlock:
 	mutex_unlock(&sysfs_mutex);
-	mutex_unlock(&parent->d_inode->i_mutex);
+	mutex_unlock(&parent_inode->i_mutex);
 	kfree(dup_name);
-	dput(old_dentry);
-	dput(new_dentry);
- out:
+out_release:
+	iput(parent_inode);
+	post_rename(&todo);
+	sysfs_release_supers();
+out:
 	mutex_unlock(&sysfs_rename_mutex);
 	return error;
 }
@@ -869,10 +943,12 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
 {
 	struct sysfs_dirent *sd = kobj->sd;
 	struct sysfs_dirent *new_parent_sd;
-	struct dentry *old_parent, *new_parent = NULL;
-	struct dentry *old_dentry = NULL, *new_dentry = NULL;
+	struct list_head todo;
+	struct sysfs_rename_struct *srs;
+	struct inode *old_parent_inode = NULL, *new_parent_inode = NULL;
 	int error;
 
+	INIT_LIST_HEAD(&todo);
 	mutex_lock(&sysfs_rename_mutex);
 	BUG_ON(!sd->s_parent);
 	new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root;
@@ -881,26 +957,29 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
 	if (sd->s_parent == new_parent_sd)
 		goto out;	/* nothing to move */
 
-	/* get dentries */
-	old_dentry = sysfs_get_dentry(sysfs_sb, sd);
-	if (IS_ERR(old_dentry)) {
-		error = PTR_ERR(old_dentry);
-		old_dentry = NULL;
-		goto out;
-	}
-	old_parent = old_dentry->d_parent;
+	sysfs_grab_supers();
+	error = prep_rename(&todo, sd, new_parent_sd, sd->s_name);
+	if (error)
+		goto out_release;
 
-	new_parent = sysfs_get_dentry(sysfs_sb, new_parent_sd);
-	if (IS_ERR(new_parent)) {
-		error = PTR_ERR(new_parent);
-		new_parent = NULL;
-		goto out;
-	}
+	error = -ENOMEM;
+	mutex_lock(&sysfs_mutex);
+	old_parent_inode = sysfs_get_inode(sd->s_parent);
+	mutex_unlock(&sysfs_mutex);
+	if (!old_parent_inode)
+		goto out_release;
+
+	error = -ENOMEM;
+	mutex_lock(&sysfs_mutex);
+	new_parent_inode = sysfs_get_inode(new_parent_sd);
+	mutex_unlock(&sysfs_mutex);
+	if (!new_parent_inode)
+		goto out_release;
 
 again:
-	mutex_lock(&old_parent->d_inode->i_mutex);
-	if (!mutex_trylock(&new_parent->d_inode->i_mutex)) {
-		mutex_unlock(&old_parent->d_inode->i_mutex);
+	mutex_lock(&old_parent_inode->i_mutex);
+	if (!mutex_trylock(&new_parent_inode->i_mutex)) {
+		mutex_unlock(&old_parent_inode->i_mutex);
 		goto again;
 	}
 	mutex_lock(&sysfs_mutex);
@@ -909,14 +988,11 @@ again:
 	if (sysfs_find_dirent(new_parent_sd, sd->s_name))
 		goto out_unlock;
 
-	error = -ENOMEM;
-	new_dentry = d_alloc_name(new_parent, sd->s_name);
-	if (!new_dentry)
-		goto out_unlock;
-
 	error = 0;
-	d_add(new_dentry, NULL);
-	d_move(old_dentry, new_dentry);
+	list_for_each_entry(srs, &todo, list) {
+		d_add(srs->new_dentry, NULL);
+		d_move(srs->old_dentry, srs->new_dentry);
+	}
 
 	/* Remove from old parent's list and insert into new parent's list. */
 	sysfs_unlink_sibling(sd);
@@ -925,14 +1001,17 @@ again:
 	sd->s_parent = new_parent_sd;
 	sysfs_link_sibling(sd);
 
- out_unlock:
+out_unlock:
 	mutex_unlock(&sysfs_mutex);
-	mutex_unlock(&new_parent->d_inode->i_mutex);
-	mutex_unlock(&old_parent->d_inode->i_mutex);
- out:
-	dput(new_parent);
-	dput(old_dentry);
-	dput(new_dentry);
+	mutex_unlock(&new_parent_inode->i_mutex);
+	mutex_unlock(&old_parent_inode->i_mutex);
+
+out_release:
+	iput(new_parent_inode);
+	iput(old_parent_inode);
+	post_rename(&todo);
+	sysfs_release_supers();
+out:
 	mutex_unlock(&sysfs_rename_mutex);
 	return error;
 }
-- 
1.5.3.rc6.17.g1911

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Containers@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/containers

Currently sysfs_chmod calls sys_setattr which in turn calls
inode_change_ok which checks to see if it is ok for the current user
space process to change tha attributes. Since sysfs_chmod_file has
only kernel mode clients denying them permission if user space is the
problem is completely inappropriate.

Therefore factor out sysfs_sd_setattr which does not call
inode_change_ok and modify sysfs_chmod_file to call it.

In addition setting victim_sd->s_mode explicitly in sysfs_chmod_file
is redundant so remove that as well.

Thanks to Tejun Heo <htejun@gmail.com>, and
Daniel Lezcano <dlezcano@fr.ibm.com> for working on this
and spotting this case.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 fs/sysfs/file.c  |    5 +----
 fs/sysfs/inode.c |   23 ++++++++++++++++-------
 fs/sysfs/sysfs.h |    1 +
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index cb5dd3f..1304b3a 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -600,13 +600,10 @@ int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
 	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 	newattrs.ia_ctime = current_fs_time(inode->i_sb);
-	rc = sysfs_setattr(victim, &newattrs);
+	rc = sysfs_sd_setattr(victim_sd, inode, &newattrs);
 
 	if (rc == 0) {
 		fsnotify_change(victim, newattrs.ia_valid);
-		mutex_lock(&sysfs_mutex);
-		victim_sd->s_mode = newattrs.ia_mode;
-		mutex_unlock(&sysfs_mutex);
 	}
 
 	mutex_unlock(&inode->i_mutex);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index eb53c63..80f8fd4 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -42,10 +42,9 @@ int __init sysfs_inode_init(void)
 	return bdi_init(&sysfs_backing_dev_info);
 }
 
-int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
+int sysfs_sd_setattr(struct sysfs_dirent *sd, struct inode *inode,
+			struct iattr * iattr)
 {
-	struct inode * inode = dentry->d_inode;
-	struct sysfs_dirent * sd = dentry->d_fsdata;
 	struct iattr * sd_iattr;
 	unsigned int ia_valid = iattr->ia_valid;
 	int error;
@@ -55,10 +54,6 @@ int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
 
 	sd_iattr = sd->s_iattr;
 
-	error = inode_change_ok(inode, iattr);
-	if (error)
-		return error;
-
 	iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */
 
 	error = inode_setattr(inode, iattr);
@@ -104,6 +99,20 @@ int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
 	return error;
 }
 
+int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+	struct inode * inode = dentry->d_inode;
+	struct sysfs_dirent * sd = dentry->d_fsdata;
+	int error;
+
+	error = inode_change_ok(inode, iattr);
+	if (error)
+		return error;
+
+	return sysfs_sd_setattr(sd, inode, iattr);
+}
+
+
 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
 {
 	inode->i_mode = mode;
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index b1bdc6e..5ee5d0a 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -154,6 +154,7 @@ static inline void sysfs_put(struct sysfs_dirent *sd)
  * inode.c
  */
 struct inode *sysfs_get_inode(struct sysfs_dirent *sd);
+int sysfs_sd_setattr(struct sysfs_dirent *sd, struct inode *inode, struct iattr *iattr);
 int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
 int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name);
 int sysfs_inode_init(void);
-- 
1.5.3.rc6.17.g1911

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Eric W. Biederman wrote:
> Currently sysfs_chmod calls sys_setattr which in turn calls
> inode_change_ok which checks to see if it is ok for the current user
> space process to change tha attributes. Since sysfs_chmod_file has
> only kernel mode clients denying them permission if user space is the
> problem is completely inappropriate.
> 
> Therefore factor out sysfs_sd_setattr which does not call
> inode_change_ok and modify sysfs_chmod_file to call it.
> 
> In addition setting victim_sd->s_mode explicitly in sysfs_chmod_file
> is redundant so remove that as well.
> 
> Thanks to Tejun Heo <htejun@gmail.com>, and
> Daniel Lezcano <dlezcano@fr.ibm.com> for working on this
> and spotting this case.
> 
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

Acked-by: Tejun Heo <tj@kernel.org>

-- 
tejun
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