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(a)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(a)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.Iab6e5ea57963d6deca5311b27fb7226…
Cc: stable(a)vger.kernel.org
Fixes: 4282d60689d4f ("tracefs: Add new tracefs file system")
Signed-off-by: Brian Norris <briannorris(a)chromium.org>
Signed-off-by: Steven Rostedt (Google) <rostedt(a)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;
commit 47311db8e8f33011d90dee76b39c8886120cdda4 upstream.
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.Iab6e5ea57963d6deca5311b27fb7226…
Cc: stable(a)vger.kernel.org
Fixes: 4282d60689d4f ("tracefs: Add new tracefs file system")
Signed-off-by: Brian Norris <briannorris(a)chromium.org>
Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org>
---
This fixes a single line of context that makes the "clean" cherry-pick
not work.
This patch also applies to 5.10, 5.4, and probably others, if I tested
correctly.
fs/tracefs/inode.c | 31 +++++++++++++++++++++++--------
1 file changed, 23 insertions(+), 8 deletions(-)
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index f2625a372a3a..066e8344934d 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 = sb->s_root->d_inode;
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;
--
2.37.2.789.g6183377224-goog