[PATCH 6.6 262/331] Revert "eventfs: Save ownership and mode"

20 Feb 2024

6.6-stable review patch.  If anyone has any objections, please let me know.
------------------
From: "Steven Rostedt (Google)" rostedt@goodmis.org
This reverts commit 9aaee3eebc91dd9ccebf6b6bc8a5f59d04ef718b.
The eventfs was not designed properly and may have some hidden bugs in it.
Linus rewrote it properly and I trust his version more than this one. Revert
the backported patches for 6.6 and re-apply all the changes to make it
equivalent to Linus's version.
Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org
Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
---
 fs/tracefs/event_inode.c |  107 +++++++----------------------------------------
 1 file changed, 16 insertions(+), 91 deletions(-)

--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -40,8 +40,6 @@ struct eventfs_inode {
  * @data:	something that the caller will want to get to later on
  * @is_freed:	Flag set if the eventfs is on its way to be freed
  * @mode:	the permission that the file or directory should have
- * @uid:	saved uid if changed
- * @gid:	saved gid if changed
  */
 struct eventfs_file {
    const char			*name;
@@ -63,22 +61,11 @@ struct eventfs_file {
    void				*data;
    unsigned int			is_freed:1;
    unsigned int			mode:31;
-	kuid_t				uid;
-	kgid_t				gid;
 };
static DEFINE_MUTEX(eventfs_mutex);
 DEFINE_STATIC_SRCU(eventfs_srcu);
-/* Mode is unsigned short, use the upper bits for flags */
-enum {
-	EVENTFS_SAVE_MODE	= BIT(16),
-	EVENTFS_SAVE_UID	= BIT(17),
-	EVENTFS_SAVE_GID	= BIT(18),
-};
-
-#define EVENTFS_MODE_MASK	(EVENTFS_SAVE_MODE - 1)
-
 static struct dentry *eventfs_root_lookup(struct inode *dir,
    				  struct dentry *dentry,
    				  unsigned int flags);
@@ -86,54 +73,8 @@ static int dcache_dir_open_wrapper(struc
 static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx);
 static int eventfs_release(struct inode *inode, struct file *file);
-static void update_attr(struct eventfs_file *ef, struct iattr *iattr)
-{
-	unsigned int ia_valid = iattr->ia_valid;
-
-	if (ia_valid & ATTR_MODE) {
-		ef->mode = (ef->mode & ~EVENTFS_MODE_MASK) |
-			(iattr->ia_mode & EVENTFS_MODE_MASK) |
-			EVENTFS_SAVE_MODE;
-	}
-	if (ia_valid & ATTR_UID) {
-		ef->mode |= EVENTFS_SAVE_UID;
-		ef->uid = iattr->ia_uid;
-	}
-	if (ia_valid & ATTR_GID) {
-		ef->mode |= EVENTFS_SAVE_GID;
-		ef->gid = iattr->ia_gid;
-	}
-}
-
-static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry,
-			     struct iattr *iattr)
-{
-	struct eventfs_file *ef;
-	int ret;
-
-	mutex_lock(&eventfs_mutex);
-	ef = dentry->d_fsdata;
-	/* The LSB is set when the eventfs_inode is being freed */
-	if (((unsigned long)ef & 1UL) || ef->is_freed) {
-		/* Do not allow changes if the event is about to be removed. */
-		mutex_unlock(&eventfs_mutex);
-		return -ENODEV;
-	}
-
-	ret = simple_setattr(idmap, dentry, iattr);
-	if (!ret)
-		update_attr(ef, iattr);
-	mutex_unlock(&eventfs_mutex);
-	return ret;
-}
-
 static const struct inode_operations eventfs_root_dir_inode_operations = {
    .lookup		= eventfs_root_lookup,
-	.setattr	= eventfs_set_attr,
-};
-
-static const struct inode_operations eventfs_file_inode_operations = {
-	.setattr	= eventfs_set_attr,
 };
static const struct file_operations eventfs_file_operations = {
@@ -144,20 +85,10 @@ static const struct file_operations even
    .release	= eventfs_release,
 };
-static void update_inode_attr(struct inode *inode, struct eventfs_file *ef)
-{
-	inode->i_mode = ef->mode & EVENTFS_MODE_MASK;
-
-	if (ef->mode & EVENTFS_SAVE_UID)
-		inode->i_uid = ef->uid;
-
-	if (ef->mode & EVENTFS_SAVE_GID)
-		inode->i_gid = ef->gid;
-}
-
 /**
  * create_file - create a file in the tracefs filesystem
- * @ef: the eventfs_file
+ * @name: the name of the file to create.
+ * @mode: the permission that the file should have.
  * @parent: parent dentry for this file.
  * @data: something that the caller will want to get to later on.
  * @fop: struct file_operations that should be used for this file.
@@ -173,7 +104,7 @@ static void update_inode_attr(struct ino
  * If tracefs is not enabled in the kernel, the value -%ENODEV will be
  * returned.
  */
-static struct dentry *create_file(struct eventfs_file *ef,
+static struct dentry *create_file(const char *name, umode_t mode,
    			  struct dentry *parent, void *data,
    			  const struct file_operations *fop)
 {
@@ -181,13 +112,13 @@ static struct dentry *create_file(struct
    struct dentry *dentry;
    struct inode *inode;
-	if (!(ef->mode & S_IFMT))
-		ef->mode |= S_IFREG;
+	if (!(mode & S_IFMT))
+		mode |= S_IFREG;
-	if (WARN_ON_ONCE(!S_ISREG(ef->mode)))
+	if (WARN_ON_ONCE(!S_ISREG(mode)))
    	return NULL;
-	dentry = eventfs_start_creating(ef->name, parent);
+	dentry = eventfs_start_creating(name, parent);
if (IS_ERR(dentry))
    	return dentry;
@@ -196,10 +127,7 @@ static struct dentry *create_file(struct
    if (unlikely(!inode))
    	return eventfs_failed_creating(dentry);
-	/* If the user updated the directory's attributes, use them */
-	update_inode_attr(inode, ef);
-
-	inode->i_op = &eventfs_file_inode_operations;
+	inode->i_mode = mode;
    inode->i_fop = fop;
    inode->i_private = data;
@@ -212,7 +140,7 @@ static struct dentry *create_file(struct
/**
  * create_dir - create a dir in the tracefs filesystem
- * @ei: the eventfs_inode that represents the directory to create
+ * @name: the name of the file to create.
  * @parent: parent dentry for this file.
  * @data: something that the caller will want to get to later on.
  *
@@ -227,14 +155,13 @@ static struct dentry *create_file(struct
  * If tracefs is not enabled in the kernel, the value -%ENODEV will be
  * returned.
  */
-static struct dentry *create_dir(struct eventfs_file *ef,
-				 struct dentry *parent, void *data)
+static struct dentry *create_dir(const char *name, struct dentry *parent, void *data)
 {
    struct tracefs_inode *ti;
    struct dentry *dentry;
    struct inode *inode;
-	dentry = eventfs_start_creating(ef->name, parent);
+	dentry = eventfs_start_creating(name, parent);
    if (IS_ERR(dentry))
    	return dentry;
@@ -242,8 +169,7 @@ static struct dentry *create_dir(struct
    if (unlikely(!inode))
    	return eventfs_failed_creating(dentry);
-	update_inode_attr(inode, ef);
-
+	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
    inode->i_op = &eventfs_root_dir_inode_operations;
    inode->i_fop = &eventfs_file_operations;
    inode->i_private = data;
@@ -380,9 +306,10 @@ create_dentry(struct eventfs_file *ef, s
    	inode_lock(parent->d_inode);
if (ef->ei)
-		dentry = create_dir(ef, parent, ef->data);
+		dentry = create_dir(ef->name, parent, ef->data);
    else
-		dentry = create_file(ef, parent, ef->data, ef->fop);
+		dentry = create_file(ef->name, ef->mode, parent,
+				     ef->data, ef->fop);
if (!lookup)
    	inode_unlock(parent->d_inode);
@@ -548,7 +475,6 @@ static int dcache_dir_open_wrapper(struc
    	if (d) {
    		struct dentry **tmp;
-
    		tmp = krealloc(dentries, sizeof(d) * (cnt + 2), GFP_KERNEL);
    		if (!tmp)
    			break;
@@ -623,14 +549,13 @@ static struct eventfs_file *eventfs_prep
    		return ERR_PTR(-ENOMEM);
    	}
    	INIT_LIST_HEAD(&ef->ei->e_top_files);
-		ef->mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
    } else {
    	ef->ei = NULL;
-		ef->mode = mode;
    }
ef->iop = iop;
    ef->fop = fop;
+	ef->mode = mode;
    ef->data = data;
    return ef;
 }

    

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[PATCH 6.6 262/331] Revert "eventfs: Save ownership and mode"