FAILED: patch "[PATCH] tracefs: Only clobber mode/uid/gid on remount if asked" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] tracefs: Only clobber mode/uid/gid on remount if asked" failed to apply to 5.15-stable tree

[gregkh]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

Possible dependencies:

47311db8e8f3 ("tracefs: Only clobber mode/uid/gid on remount if asked")
851e99ebeec3 ("tracefs: Set the group ownership in apply_options() not parse_options()")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 47311db8e8f33011d90dee76b39c8886120cdda4 Mon Sep 17 00:00:00 2001
From: Brian Norris <briannorris@chromium.org>
Date: Fri, 26 Aug 2022 17:44:17 -0700
Subject: [PATCH] tracefs: Only clobber mode/uid/gid on remount if asked

Users may have explicitly configured their tracefs permissions; we
shouldn't overwrite those just because a second mount appeared.

Only clobber if the options were provided at mount time.

Note: the previous behavior was especially surprising in the presence of
automounted /sys/kernel/debug/tracing/.

Existing behavior:

  ## Pre-existing status: tracefs is 0755.
  # stat -c '%A' /sys/kernel/tracing/
  drwxr-xr-x

  ## (Re)trigger the automount.
  # umount /sys/kernel/debug/tracing
  # stat -c '%A' /sys/kernel/debug/tracing/.
  drwx------

  ## Unexpected: the automount changed mode for other mount instances.
  # stat -c '%A' /sys/kernel/tracing/
  drwx------

New behavior (after this change):

  ## Pre-existing status: tracefs is 0755.
  # stat -c '%A' /sys/kernel/tracing/
  drwxr-xr-x

  ## (Re)trigger the automount.
  # umount /sys/kernel/debug/tracing
  # stat -c '%A' /sys/kernel/debug/tracing/.
  drwxr-xr-x

  ## Expected: the automount does not change other mount instances.
  # stat -c '%A' /sys/kernel/tracing/
  drwxr-xr-x

Link: https://lkml.kernel.org/r/20220826174353.2.Iab6e5ea57963d6deca5311b27fb7226790d44406@changeid

Cc: stable@vger.kernel.org
Fixes: 4282d60689d4f ("tracefs: Add new tracefs file system")
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 81d26abf486f..da85b3979195 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -141,6 +141,8 @@ struct tracefs_mount_opts {
 	kuid_t uid;
 	kgid_t gid;
 	umode_t mode;
+	/* Opt_* bitfield. */
+	unsigned int opts;
 };
 
 enum {
@@ -241,6 +243,7 @@ static int tracefs_parse_options(char *data, struct tracefs_mount_opts *opts)
 	kgid_t gid;
 	char *p;
 
+	opts->opts = 0;
 	opts->mode = TRACEFS_DEFAULT_MODE;
 
 	while ((p = strsep(&data, ",")) != NULL) {
@@ -275,24 +278,36 @@ static int tracefs_parse_options(char *data, struct tracefs_mount_opts *opts)
 		 * but traditionally tracefs has ignored all mount options
 		 */
 		}
+
+		opts->opts |= BIT(token);
 	}
 
 	return 0;
 }
 
-static int tracefs_apply_options(struct super_block *sb)
+static int tracefs_apply_options(struct super_block *sb, bool remount)
 {
 	struct tracefs_fs_info *fsi = sb->s_fs_info;
 	struct inode *inode = d_inode(sb->s_root);
 	struct tracefs_mount_opts *opts = &fsi->mount_opts;
 
-	inode->i_mode &= ~S_IALLUGO;
-	inode->i_mode |= opts->mode;
+	/*
+	 * On remount, only reset mode/uid/gid if they were provided as mount
+	 * options.
+	 */
+
+	if (!remount || opts->opts & BIT(Opt_mode)) {
+		inode->i_mode &= ~S_IALLUGO;
+		inode->i_mode |= opts->mode;
+	}
 
-	inode->i_uid = opts->uid;
+	if (!remount || opts->opts & BIT(Opt_uid))
+		inode->i_uid = opts->uid;
 
-	/* Set all the group ids to the mount option */
-	set_gid(sb->s_root, opts->gid);
+	if (!remount || opts->opts & BIT(Opt_gid)) {
+		/* Set all the group ids to the mount option */
+		set_gid(sb->s_root, opts->gid);
+	}
 
 	return 0;
 }
@@ -307,7 +322,7 @@ static int tracefs_remount(struct super_block *sb, int *flags, char *data)
 	if (err)
 		goto fail;
 
-	tracefs_apply_options(sb);
+	tracefs_apply_options(sb, true);
 
 fail:
 	return err;
@@ -359,7 +374,7 @@ static int trace_fill_super(struct super_block *sb, void *data, int silent)
 
 	sb->s_op = &tracefs_super_operations;
 
-	tracefs_apply_options(sb);
+	tracefs_apply_options(sb, false);
 
 	return 0;
 

Re: FAILED: patch "[PATCH] tracefs: Only clobber mode/uid/gid on remount if asked" failed to apply to 5.15-stable tree

[Brian Norris]

Hi Greg,

On Fri, Sep 9, 2022 at 11:31 AM <gregkh@linuxfoundation.org> wrote:
> The patch below does not apply to the 5.15-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

Did something go wrong in your automation? The same patch applies
cleanly to me (currently, on top of v5.15.67).

> Possible dependencies:
>
> 47311db8e8f3 ("tracefs: Only clobber mode/uid/gid on remount if asked")

That's $subject patch. OK, so not that one.

> 851e99ebeec3 ("tracefs: Set the group ownership in apply_options() not parse_options()")

That one *is* a dependency, but it's already backported to 5.15.y as
of several months ago:

commit 6db927ce66ac68bf732f0b14190791458e75047a
Author:     Steven Rostedt (Google) <rostedt@goodmis.org>
AuthorDate: Fri Feb 25 15:34:26 2022 -0500
Commit:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CommitDate: Wed Mar 2 11:48:05 2022 +0100

    tracefs: Set the group ownership in apply_options() not parse_options()

    commit 851e99ebeec3f4a672bb5010cf1ece095acee447 upstream.

So I'm not sure what to do to fix the backporting, other than ping back here.

I think the same applies to the 5.10.y rejection notice, and possibly
a few others.

Brian

Re: FAILED: patch "[PATCH] tracefs: Only clobber mode/uid/gid on remount if asked" failed to apply to 5.15-stable tree

[Greg Kroah-Hartman]

On Mon, Sep 12, 2022 at 03:23:42PM -0700, Brian Norris wrote:
> Hi Greg,
> 
> On Fri, Sep 9, 2022 at 11:31 AM <gregkh@linuxfoundation.org> wrote:
> > The patch below does not apply to the 5.15-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> 
> Did something go wrong in your automation? The same patch applies
> cleanly to me (currently, on top of v5.15.67).
> 
> > Possible dependencies:
> >
> > 47311db8e8f3 ("tracefs: Only clobber mode/uid/gid on remount if asked")
> 
> That's $subject patch. OK, so not that one.
> 
> > 851e99ebeec3 ("tracefs: Set the group ownership in apply_options() not parse_options()")
> 
> That one *is* a dependency, but it's already backported to 5.15.y as
> of several months ago:
> 
> commit 6db927ce66ac68bf732f0b14190791458e75047a
> Author:     Steven Rostedt (Google) <rostedt@goodmis.org>
> AuthorDate: Fri Feb 25 15:34:26 2022 -0500
> Commit:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> CommitDate: Wed Mar 2 11:48:05 2022 +0100
> 
>     tracefs: Set the group ownership in apply_options() not parse_options()
> 
>     commit 851e99ebeec3f4a672bb5010cf1ece095acee447 upstream.
> 
> So I'm not sure what to do to fix the backporting, other than ping back here.
> 
> I think the same applies to the 5.10.y rejection notice, and possibly
> a few others.

Here is what patch says:

Applying tracefs-only-clobber-mode-uid-gid-on-remount-if-asked.patch to linux-5.15.y
Applying patch tracefs-only-clobber-mode-uid-gid-on-remount-if-asked.patch
patching file fs/tracefs/inode.c
Hunk #3 FAILED at 278.
1 out of 5 hunks FAILED -- rejects in file fs/tracefs/inode.c
Patch tracefs-only-clobber-mode-uid-gid-on-remount-if-asked.patch does not apply (enforce with -f)
quilt returned 1, with 0 fuzz and 1 rejects

How did you apply the patch to 5.15.y that worked?

thanks,

greg k-h

Re: FAILED: patch "[PATCH] tracefs: Only clobber mode/uid/gid on remount if asked" failed to apply to 5.15-stable tree

[Brian Norris]

On Tue, Sep 13, 2022 at 4:34 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> Here is what patch says:
>
> Applying tracefs-only-clobber-mode-uid-gid-on-remount-if-asked.patch to linux-5.15.y
> Applying patch tracefs-only-clobber-mode-uid-gid-on-remount-if-asked.patch
> patching file fs/tracefs/inode.c
> Hunk #3 FAILED at 278.
> 1 out of 5 hunks FAILED -- rejects in file fs/tracefs/inode.c
> Patch tracefs-only-clobber-mode-uid-gid-on-remount-if-asked.patch does not apply (enforce with -f)
> quilt returned 1, with 0 fuzz and 1 rejects
>
> How did you apply the patch to 5.15.y that worked?

Hmm, I suppose I have 'git am' doing 3-way merges for me, which resolve OK:

$ curl https://lore.kernel.org/all/166274826116451@kroah.com/raw | git am -
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  6614  100  6614    0     0  27768      0 --:--:-- --:--:-- --:--:-- 27789
Applying: FAILED: patch "[PATCH] tracefs: Only clobber mode/uid/gid on
remount if asked" failed to apply to 5.15-stable tree
Using index info to reconstruct a base tree...
M fs/tracefs/inode.c
Falling back to patching base and 3-way merge...
Auto-merging fs/tracefs/inode.c

And originally, I guess I was testing 'git cherry-pick', not literally
this patch. That also does some "auto-merging":

$ git cherry-pick 47311db8e8f33011d90dee76b39c8886120cdda4
Auto-merging fs/tracefs/inode.c
[detached HEAD e9f574cc9df9] tracefs: Only clobber mode/uid/gid on
remount if asked
 Date: Fri Aug 26 17:44:17 2022 -0700
 1 file changed, 23 insertions(+), 8 deletions(-)

I'll generate a clean patch based on the above, but it'll look awfully
similar. (I think there's a single line of context that looks
different, a few lines away.) Stay tuned.


Brian