| Message ID | 4b235bf62c99f1f1196edc9da4258167314dc3c3.1725481503.git.josef@toxicpanda.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fanotify: add pre-content hooks | expand |
On Wed, Sep 4, 2024 at 10:29 PM Josef Bacik <josef@toxicpanda.com> wrote: > > From: Amir Goldstein <amir73il@gmail.com> > > FS_PRE_ACCESS or FS_PRE_MODIFY will be generated on open depending on > file open mode. The pre-content event will be generated in addition to > FS_OPEN_PERM, but without sb_writers held and after file was truncated > in case file was opened with O_CREAT and/or O_TRUNC. > > The event will have a range info of (0..0) to provide an opportunity > to fill entire file content on open. > > Signed-off-by: Amir Goldstein <amir73il@gmail.com> > Reviewed-by: Christian Brauner <brauner@kernel.org> > --- > fs/namei.c | 9 +++++++++ > include/linux/fsnotify.h | 10 +++++++++- > 2 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/fs/namei.c b/fs/namei.c > index 3a4c40e12f78..c16487e3742d 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -3735,6 +3735,15 @@ static int do_open(struct nameidata *nd, > } > if (do_truncate) > mnt_drop_write(nd->path.mnt); > + > + /* > + * This permission hook is different than fsnotify_open_perm() hook. > + * This is a pre-content hook that is called without sb_writers held > + * and after the file was truncated. > + */ > + if (!error) > + error = fsnotify_file_perm(file, MAY_OPEN); > + Josef, Please change that for v6 to: error = fsnotify_file_area_perm(file, MAY_OPEN, &file->f_pos, 0); ... > return error; > } > > diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h > index 7600a0c045ba..fb3837b8de4c 100644 > --- a/include/linux/fsnotify.h > +++ b/include/linux/fsnotify.h > @@ -168,6 +168,10 @@ static inline int fsnotify_file_area_perm(struct file *file, int perm_mask, > fsnotify_mask = FS_PRE_MODIFY; > else if (perm_mask & (MAY_READ | MAY_ACCESS)) > fsnotify_mask = FS_PRE_ACCESS; > + else if (perm_mask & MAY_OPEN && file->f_mode & FMODE_WRITER) > + fsnotify_mask = FS_PRE_MODIFY; > + else if (perm_mask & MAY_OPEN) > + fsnotify_mask = FS_PRE_ACCESS; > else > return 0; > > @@ -176,10 +180,14 @@ static inline int fsnotify_file_area_perm(struct file *file, int perm_mask, > > /* > * fsnotify_file_perm - permission hook before file access > + * > + * Called from read()/write() with perm_mask MAY_READ/MAY_WRITE. > + * Called from open() with MAY_OPEN without sb_writers held and after the file > + * was truncated. Note that this is a different event from fsnotify_open_perm(). > */ > static inline int fsnotify_file_perm(struct file *file, int perm_mask) > { > - return fsnotify_file_area_perm(file, perm_mask, NULL, 0); > + return fsnotify_file_area_perm(file, perm_mask, &file->f_pos, 0); > } ... and drop this change, because this change will make readdir() start reporting odd file ranges and HSM won't be able to tell the difference between an opendir() and a readdir(). And I will send an extra patch for reporting an event with range [size..size] for truncate(size). Thanks, Amir.
diff --git a/fs/namei.c b/fs/namei.c index 3a4c40e12f78..c16487e3742d 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3735,6 +3735,15 @@ static int do_open(struct nameidata *nd, } if (do_truncate) mnt_drop_write(nd->path.mnt); + + /* + * This permission hook is different than fsnotify_open_perm() hook. + * This is a pre-content hook that is called without sb_writers held + * and after the file was truncated. + */ + if (!error) + error = fsnotify_file_perm(file, MAY_OPEN); + return error; } diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h index 7600a0c045ba..fb3837b8de4c 100644 --- a/include/linux/fsnotify.h +++ b/include/linux/fsnotify.h @@ -168,6 +168,10 @@ static inline int fsnotify_file_area_perm(struct file *file, int perm_mask, fsnotify_mask = FS_PRE_MODIFY; else if (perm_mask & (MAY_READ | MAY_ACCESS)) fsnotify_mask = FS_PRE_ACCESS; + else if (perm_mask & MAY_OPEN && file->f_mode & FMODE_WRITER) + fsnotify_mask = FS_PRE_MODIFY; + else if (perm_mask & MAY_OPEN) + fsnotify_mask = FS_PRE_ACCESS; else return 0; @@ -176,10 +180,14 @@ static inline int fsnotify_file_area_perm(struct file *file, int perm_mask, /* * fsnotify_file_perm - permission hook before file access + * + * Called from read()/write() with perm_mask MAY_READ/MAY_WRITE. + * Called from open() with MAY_OPEN without sb_writers held and after the file + * was truncated. Note that this is a different event from fsnotify_open_perm(). */ static inline int fsnotify_file_perm(struct file *file, int perm_mask) { - return fsnotify_file_area_perm(file, perm_mask, NULL, 0); + return fsnotify_file_area_perm(file, perm_mask, &file->f_pos, 0); } /*