On Wed, 20 Dec 2023 10:50:17 -0500 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx> > > Dongliang reported: > > I found that in the latest version, the nodes of tracefs have been > changed to dynamically created. > > This has caused me to encounter a problem where the gid I specified in > the mounting parameters cannot apply to all files, as in the following > situation: > > /data/tmp/events # mount | grep tracefs > tracefs on /data/tmp type tracefs (rw,seclabel,relatime,gid=3012) > > gid 3012 = readtracefs > > /data/tmp # ls -lh > total 0 > -r--r----- 1 root readtracefs 0 1970-01-01 08:00 README > -r--r----- 1 root readtracefs 0 1970-01-01 08:00 available_events > > ums9621_1h10:/data/tmp/events # ls -lh > total 0 > drwxr-xr-x 2 root root 0 2023-12-19 00:56 alarmtimer > drwxr-xr-x 2 root root 0 2023-12-19 00:56 asoc > > It will prevent certain applications from accessing tracefs properly, I > try to avoid this issue by making the following modifications. > > To fix this, have the files created default to taking the ownership of > the parent dentry unless the ownership was previously set by the user. > > Link: https://lore.kernel.org/linux-trace-kernel/1703063706-30539-1-git-send-email-dongliang.cui@xxxxxxxxxx/ > I forgot to add: Cc: stable@xxxxxxxxxxxxxxx Fixes: 28e12c09f5aa0 ("eventfs: Save ownership and mode") -- Steve > Reported-by: Dongliang Cui <cuidongliang390@xxxxxxxxx> > Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> > --- > fs/tracefs/event_inode.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c > index 43e237864a42..2ccc849a5bda 100644 > --- a/fs/tracefs/event_inode.c > +++ b/fs/tracefs/event_inode.c > @@ -148,7 +148,8 @@ static const struct file_operations eventfs_file_operations = { > .release = eventfs_release, > }; > > -static void update_inode_attr(struct inode *inode, struct eventfs_attr *attr, umode_t mode) > +static void update_inode_attr(struct dentry *dentry, struct inode *inode, > + struct eventfs_attr *attr, umode_t mode) > { > if (!attr) { > inode->i_mode = mode; > @@ -162,9 +163,13 @@ static void update_inode_attr(struct inode *inode, struct eventfs_attr *attr, um > > if (attr->mode & EVENTFS_SAVE_UID) > inode->i_uid = attr->uid; > + else > + inode->i_uid = d_inode(dentry->d_parent)->i_uid; > > if (attr->mode & EVENTFS_SAVE_GID) > inode->i_gid = attr->gid; > + else > + inode->i_gid = d_inode(dentry->d_parent)->i_gid; > } > > /** > @@ -206,7 +211,7 @@ static struct dentry *create_file(const char *name, umode_t mode, > return eventfs_failed_creating(dentry); > > /* If the user updated the directory's attributes, use them */ > - update_inode_attr(inode, attr, mode); > + update_inode_attr(dentry, inode, attr, mode); > > inode->i_op = &eventfs_file_inode_operations; > inode->i_fop = fop; > @@ -242,7 +247,8 @@ static struct dentry *create_dir(struct eventfs_inode *ei, struct dentry *parent > return eventfs_failed_creating(dentry); > > /* If the user updated the directory's attributes, use them */ > - update_inode_attr(inode, &ei->attr, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO); > + update_inode_attr(dentry, inode, &ei->attr, > + S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO); > > inode->i_op = &eventfs_root_dir_inode_operations; > inode->i_fop = &eventfs_file_operations;
