May 2024 - Linux-stable-mirror

[for-linus][PATCH 9/9] eventfs: Have "events" directory get permissions from its parent

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> The events directory gets its permissions from the root inode. But this can cause an inconsistency if the instances directory changes its permissions, as the permissions of the created directories under it should inherit the permissions of the instances directory when directories under it are created. Currently the behavior is: # cd /sys/kernel/tracing # chgrp 1002 instances # mkdir instances/foo # ls -l instances/foo [..] -r--r----- 1 root lkp 0 May 1 18:55 buffer_total_size_kb -rw-r----- 1 root lkp 0 May 1 18:55 current_tracer -rw-r----- 1 root lkp 0 May 1 18:55 error_log drwxr-xr-x 1 root root 0 May 1 18:55 events --w------- 1 root lkp 0 May 1 18:55 free_buffer drwxr-x--- 2 root lkp 0 May 1 18:55 options drwxr-x--- 10 root lkp 0 May 1 18:55 per_cpu -rw-r----- 1 root lkp 0 May 1 18:55 set_event All the files and directories under "foo" has the "lkp" group except the "events" directory. That's because its getting its default value from the mount point instead of its parent. Have the "events" directory make its default value based on its parent's permissions. That now gives: # ls -l instances/foo [..] -rw-r----- 1 root lkp 0 May 1 21:16 buffer_subbuf_size_kb -r--r----- 1 root lkp 0 May 1 21:16 buffer_total_size_kb -rw-r----- 1 root lkp 0 May 1 21:16 current_tracer -rw-r----- 1 root lkp 0 May 1 21:16 error_log drwxr-xr-x 1 root lkp 0 May 1 21:16 events --w------- 1 root lkp 0 May 1 21:16 free_buffer drwxr-x--- 2 root lkp 0 May 1 21:16 options drwxr-x--- 10 root lkp 0 May 1 21:16 per_cpu -rw-r----- 1 root lkp 0 May 1 21:16 set_event Link: https://lore.kernel.org/linux-trace-kernel/20240502200906.161887248@goodmis… Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Cc: Andrew Morton <akpm(a)linux-foundation.org> Fixes: 8186fff7ab649 ("tracefs/eventfs: Use root and instance inodes as default ownership") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- fs/tracefs/event_inode.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 6e08405892ae..a878cea70f4c 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -37,6 +37,7 @@ static DEFINE_MUTEX(eventfs_mutex); struct eventfs_root_inode { struct eventfs_inode ei; + struct inode *parent_inode; struct dentry *events_dir; }; @@ -226,12 +227,23 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry, static void update_events_attr(struct eventfs_inode *ei, struct super_block *sb) { - struct inode *root; + struct eventfs_root_inode *rei; + struct inode *parent; + + rei = get_root_inode(ei); + + /* Use the parent inode permissions unless root set its permissions */ + parent = rei->parent_inode; - /* Get the tracefs root inode. */ - root = d_inode(sb->s_root); - ei->attr.uid = root->i_uid; - ei->attr.gid = root->i_gid; + if (rei->ei.attr.mode & EVENTFS_SAVE_UID) + ei->attr.uid = rei->ei.attr.uid; + else + ei->attr.uid = parent->i_uid; + + if (rei->ei.attr.mode & EVENTFS_SAVE_GID) + ei->attr.gid = rei->ei.attr.gid; + else + ei->attr.gid = parent->i_gid; } static void set_top_events_ownership(struct inode *inode) @@ -817,6 +829,7 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry // Note: we have a ref to the dentry from tracefs_start_creating() rei = get_root_inode(ei); rei->events_dir = dentry; + rei->parent_inode = d_inode(dentry->d_sb->s_root); ei->entries = entries; ei->nr_entries = size; @@ -826,10 +839,15 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry uid = d_inode(dentry->d_parent)->i_uid; gid = d_inode(dentry->d_parent)->i_gid; - /* This is used as the default ownership of the files and directories */ ei->attr.uid = uid; ei->attr.gid = gid; + /* + * When the "events" directory is created, it takes on the + * permissions of its parent. But can be reset on remount. + */ + ei->attr.mode |= EVENTFS_SAVE_UID | EVENTFS_SAVE_GID; + INIT_LIST_HEAD(&ei->children); INIT_LIST_HEAD(&ei->list); -- 2.43.0

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[for-linus][PATCH 8/9] eventfs: Do not treat events directory different than other directories

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> Treat the events directory the same as other directories when it comes to permissions. The events directory was considered different because it's dentry is persistent, whereas the other directory dentries are created when accessed. But the way tracefs now does its ownership by using the root dentry's permissions as the default permissions, the events directory can get out of sync when a remount is performed setting the group and user permissions. Remove the special case for the events directory on setting the attributes. This allows the updates caused by remount to work properly as well as simplifies the code. Link: https://lore.kernel.org/linux-trace-kernel/20240502200906.002923579@goodmis… Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Cc: Andrew Morton <akpm(a)linux-foundation.org> Fixes: 8186fff7ab649 ("tracefs/eventfs: Use root and instance inodes as default ownership") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- fs/tracefs/event_inode.c | 16 +--------------- 1 file changed, 1 insertion(+), 15 deletions(-) diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 9dacf65c0b6e..6e08405892ae 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -206,21 +206,7 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry, * determined by the parent directory. */ if (dentry->d_inode->i_mode & S_IFDIR) { - /* - * The events directory dentry is never freed, unless its - * part of an instance that is deleted. It's attr is the - * default for its child files and directories. - * Do not update it. It's not used for its own mode or ownership. - */ - if (ei->is_events) { - /* But it still needs to know if it was modified */ - if (iattr->ia_valid & ATTR_UID) - ei->attr.mode |= EVENTFS_SAVE_UID; - if (iattr->ia_valid & ATTR_GID) - ei->attr.mode |= EVENTFS_SAVE_GID; - } else { - update_attr(&ei->attr, iattr); - } + update_attr(&ei->attr, iattr); } else { name = dentry->d_name.name; -- 2.43.0

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[for-linus][PATCH 7/9] eventfs: Do not differentiate the toplevel events directory

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> The toplevel events directory is really no different than the events directory of instances. Having the two be different caused inconsistencies and made it harder to fix the permissions bugs. Make all events directories act the same. Link: https://lore.kernel.org/linux-trace-kernel/20240502200905.846448710@goodmis… Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Cc: Andrew Morton <akpm(a)linux-foundation.org> Fixes: 8186fff7ab649 ("tracefs/eventfs: Use root and instance inodes as default ownership") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- fs/tracefs/event_inode.c | 29 ++++++++--------------------- fs/tracefs/internal.h | 7 +++---- 2 files changed, 11 insertions(+), 25 deletions(-) diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 15a2a9c3c62b..9dacf65c0b6e 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -68,7 +68,6 @@ enum { EVENTFS_SAVE_MODE = BIT(16), EVENTFS_SAVE_UID = BIT(17), EVENTFS_SAVE_GID = BIT(18), - EVENTFS_TOPLEVEL = BIT(19), }; #define EVENTFS_MODE_MASK (EVENTFS_SAVE_MODE - 1) @@ -239,14 +238,10 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry, return ret; } -static void update_top_events_attr(struct eventfs_inode *ei, struct super_block *sb) +static void update_events_attr(struct eventfs_inode *ei, struct super_block *sb) { struct inode *root; - /* Only update if the "events" was on the top level */ - if (!ei || !(ei->attr.mode & EVENTFS_TOPLEVEL)) - return; - /* Get the tracefs root inode. */ root = d_inode(sb->s_root); ei->attr.uid = root->i_uid; @@ -259,10 +254,10 @@ static void set_top_events_ownership(struct inode *inode) struct eventfs_inode *ei = ti->private; /* The top events directory doesn't get automatically updated */ - if (!ei || !ei->is_events || !(ei->attr.mode & EVENTFS_TOPLEVEL)) + if (!ei || !ei->is_events) return; - update_top_events_attr(ei, inode->i_sb); + update_events_attr(ei, inode->i_sb); if (!(ei->attr.mode & EVENTFS_SAVE_UID)) inode->i_uid = ei->attr.uid; @@ -291,7 +286,7 @@ static int eventfs_permission(struct mnt_idmap *idmap, return generic_permission(idmap, inode, mask); } -static const struct inode_operations eventfs_root_dir_inode_operations = { +static const struct inode_operations eventfs_dir_inode_operations = { .lookup = eventfs_root_lookup, .setattr = eventfs_set_attr, .getattr = eventfs_get_attr, @@ -359,7 +354,7 @@ static struct eventfs_inode *eventfs_find_events(struct dentry *dentry) // Walk upwards until you find the events inode } while (!ei->is_events); - update_top_events_attr(ei, dentry->d_sb); + update_events_attr(ei, dentry->d_sb); return ei; } @@ -465,7 +460,7 @@ static struct dentry *lookup_dir_entry(struct dentry *dentry, 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_op = &eventfs_dir_inode_operations; inode->i_fop = &eventfs_file_operations; /* All directories will have the same inode number */ @@ -845,14 +840,6 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry uid = d_inode(dentry->d_parent)->i_uid; gid = d_inode(dentry->d_parent)->i_gid; - /* - * If the events directory is of the top instance, then parent - * is NULL. Set the attr.mode to reflect this and its permissions will - * default to the tracefs root dentry. - */ - if (!parent) - ei->attr.mode = EVENTFS_TOPLEVEL; - /* This is used as the default ownership of the files and directories */ ei->attr.uid = uid; ei->attr.gid = gid; @@ -861,13 +848,13 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry INIT_LIST_HEAD(&ei->list); ti = get_tracefs(inode); - ti->flags |= TRACEFS_EVENT_INODE | TRACEFS_EVENT_TOP_INODE; + ti->flags |= TRACEFS_EVENT_INODE; ti->private = ei; inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; inode->i_uid = uid; inode->i_gid = gid; - inode->i_op = &eventfs_root_dir_inode_operations; + inode->i_op = &eventfs_dir_inode_operations; inode->i_fop = &eventfs_file_operations; dentry->d_fsdata = get_ei(ei); diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 29f0c999975b..f704d8348357 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -4,10 +4,9 @@ enum { TRACEFS_EVENT_INODE = BIT(1), - TRACEFS_EVENT_TOP_INODE = BIT(2), - TRACEFS_GID_PERM_SET = BIT(3), - TRACEFS_UID_PERM_SET = BIT(4), - TRACEFS_INSTANCE_INODE = BIT(5), + TRACEFS_GID_PERM_SET = BIT(2), + TRACEFS_UID_PERM_SET = BIT(3), + TRACEFS_INSTANCE_INODE = BIT(4), }; struct tracefs_inode { -- 2.43.0

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[for-linus][PATCH 6/9] tracefs: Still use mount point as default permissions for instances

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> If the instances directory's permissions were never change, then have it and its children use the mount point permissions as the default. Currently, the permissions of instance directories are determined by the instance directory's permissions itself. But if the tracefs file system is remounted and changes the permissions, the instance directory and its children should use the new permission. But because both the instance directory and its children use the instance directory's inode for permissions, it misses the update. To demonstrate this: # cd /sys/kernel/tracing/ # mkdir instances/foo # ls -ld instances/foo drwxr-x--- 5 root root 0 May 1 19:07 instances/foo # ls -ld instances drwxr-x--- 3 root root 0 May 1 18:57 instances # ls -ld current_tracer -rw-r----- 1 root root 0 May 1 18:57 current_tracer # mount -o remount,gid=1002 . # ls -ld instances drwxr-x--- 3 root root 0 May 1 18:57 instances # ls -ld instances/foo/ drwxr-x--- 5 root root 0 May 1 19:07 instances/foo/ # ls -ld current_tracer -rw-r----- 1 root lkp 0 May 1 18:57 current_tracer Notice that changing the group id to that of "lkp" did not affect the instances directory nor its children. It should have been: # ls -ld current_tracer -rw-r----- 1 root root 0 May 1 19:19 current_tracer # ls -ld instances/foo/ drwxr-x--- 5 root root 0 May 1 19:25 instances/foo/ # ls -ld instances drwxr-x--- 3 root root 0 May 1 19:19 instances # mount -o remount,gid=1002 . # ls -ld current_tracer -rw-r----- 1 root lkp 0 May 1 19:19 current_tracer # ls -ld instances drwxr-x--- 3 root lkp 0 May 1 19:19 instances # ls -ld instances/foo/ drwxr-x--- 5 root lkp 0 May 1 19:25 instances/foo/ Where all files were updated by the remount gid update. Link: https://lore.kernel.org/linux-trace-kernel/20240502200905.686838327@goodmis… Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Cc: Andrew Morton <akpm(a)linux-foundation.org> Fixes: 8186fff7ab649 ("tracefs/eventfs: Use root and instance inodes as default ownership") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- fs/tracefs/inode.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 52aa14bd2994..417c840e6403 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -180,16 +180,39 @@ static void set_tracefs_inode_owner(struct inode *inode) { struct tracefs_inode *ti = get_tracefs(inode); struct inode *root_inode = ti->private; + kuid_t uid; + kgid_t gid; + + uid = root_inode->i_uid; + gid = root_inode->i_gid; + + /* + * If the root is not the mount point, then check the root's + * permissions. If it was never set, then default to the + * mount point. + */ + if (root_inode != d_inode(root_inode->i_sb->s_root)) { + struct tracefs_inode *rti; + + rti = get_tracefs(root_inode); + root_inode = d_inode(root_inode->i_sb->s_root); + + if (!(rti->flags & TRACEFS_UID_PERM_SET)) + uid = root_inode->i_uid; + + if (!(rti->flags & TRACEFS_GID_PERM_SET)) + gid = root_inode->i_gid; + } /* * If this inode has never been referenced, then update * the permissions to the superblock. */ if (!(ti->flags & TRACEFS_UID_PERM_SET)) - inode->i_uid = root_inode->i_uid; + inode->i_uid = uid; if (!(ti->flags & TRACEFS_GID_PERM_SET)) - inode->i_gid = root_inode->i_gid; + inode->i_gid = gid; } static int tracefs_permission(struct mnt_idmap *idmap, -- 2.43.0

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[for-linus][PATCH 5/9] tracefs: Reset permissions on remount if permissions are options

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> There's an inconsistency with the way permissions are handled in tracefs. Because the permissions are generated when accessed, they default to the root inode's permission if they were never set by the user. If the user sets the permissions, then a flag is set and the permissions are saved via the inode (for tracefs files) or an internal attribute field (for eventfs). But if a remount happens that specify the permissions, all the files that were not changed by the user gets updated, but the ones that were are not. If the user were to remount the file system with a given permission, then all files and directories within that file system should be updated. This can cause security issues if a file's permission was updated but the admin forgot about it. They could incorrectly think that remounting with permissions set would update all files, but miss some. For example: # cd /sys/kernel/tracing # chgrp 1002 current_tracer # ls -l [..] -rw-r----- 1 root root 0 May 1 21:25 buffer_size_kb -rw-r----- 1 root root 0 May 1 21:25 buffer_subbuf_size_kb -r--r----- 1 root root 0 May 1 21:25 buffer_total_size_kb -rw-r----- 1 root lkp 0 May 1 21:25 current_tracer -rw-r----- 1 root root 0 May 1 21:25 dynamic_events -r--r----- 1 root root 0 May 1 21:25 dyn_ftrace_total_info -r--r----- 1 root root 0 May 1 21:25 enabled_functions Where current_tracer now has group "lkp". # mount -o remount,gid=1001 . # ls -l -rw-r----- 1 root tracing 0 May 1 21:25 buffer_size_kb -rw-r----- 1 root tracing 0 May 1 21:25 buffer_subbuf_size_kb -r--r----- 1 root tracing 0 May 1 21:25 buffer_total_size_kb -rw-r----- 1 root lkp 0 May 1 21:25 current_tracer -rw-r----- 1 root tracing 0 May 1 21:25 dynamic_events -r--r----- 1 root tracing 0 May 1 21:25 dyn_ftrace_total_info -r--r----- 1 root tracing 0 May 1 21:25 enabled_functions Everything changed but the "current_tracer". Add a new link list that keeps track of all the tracefs_inodes which has the permission flags that tell if the file/dir should use the root inode's permission or not. Then on remount, clear all the flags so that the default behavior of using the root inode's permission is done for all files and directories. Link: https://lore.kernel.org/linux-trace-kernel/20240502200905.529542160@goodmis… Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Cc: Andrew Morton <akpm(a)linux-foundation.org> Fixes: 8186fff7ab649 ("tracefs/eventfs: Use root and instance inodes as default ownership") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- fs/tracefs/event_inode.c | 29 ++++++++++++++++++ fs/tracefs/inode.c | 65 +++++++++++++++++++++++++++++++++++++++- fs/tracefs/internal.h | 7 ++++- 3 files changed, 99 insertions(+), 2 deletions(-) diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index cc8b838bbe62..15a2a9c3c62b 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -308,6 +308,35 @@ static const struct file_operations eventfs_file_operations = { .llseek = generic_file_llseek, }; +/* + * On a remount of tracefs, if UID or GID options are set, then + * the mount point inode permissions should be used. + * Reset the saved permission flags appropriately. + */ +void eventfs_remount(struct tracefs_inode *ti, bool update_uid, bool update_gid) +{ + struct eventfs_inode *ei = ti->private; + + if (!ei) + return; + + if (update_uid) + ei->attr.mode &= ~EVENTFS_SAVE_UID; + + if (update_gid) + ei->attr.mode &= ~EVENTFS_SAVE_GID; + + if (!ei->entry_attrs) + return; + + for (int i = 0; i < ei->nr_entries; i++) { + if (update_uid) + ei->entry_attrs[i].mode &= ~EVENTFS_SAVE_UID; + if (update_gid) + ei->entry_attrs[i].mode &= ~EVENTFS_SAVE_GID; + } +} + /* Return the evenfs_inode of the "events" directory */ static struct eventfs_inode *eventfs_find_events(struct dentry *dentry) { diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 5545e6bf7d26..52aa14bd2994 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -30,20 +30,47 @@ static struct vfsmount *tracefs_mount; static int tracefs_mount_count; static bool tracefs_registered; +/* + * Keep track of all tracefs_inodes in order to update their + * flags if necessary on a remount. + */ +static DEFINE_SPINLOCK(tracefs_inode_lock); +static LIST_HEAD(tracefs_inodes); + static struct inode *tracefs_alloc_inode(struct super_block *sb) { struct tracefs_inode *ti; + unsigned long flags; ti = kmem_cache_alloc(tracefs_inode_cachep, GFP_KERNEL); if (!ti) return NULL; + spin_lock_irqsave(&tracefs_inode_lock, flags); + list_add_rcu(&ti->list, &tracefs_inodes); + spin_unlock_irqrestore(&tracefs_inode_lock, flags); + return &ti->vfs_inode; } +static void tracefs_free_inode_rcu(struct rcu_head *rcu) +{ + struct tracefs_inode *ti; + + ti = container_of(rcu, struct tracefs_inode, rcu); + kmem_cache_free(tracefs_inode_cachep, ti); +} + static void tracefs_free_inode(struct inode *inode) { - kmem_cache_free(tracefs_inode_cachep, get_tracefs(inode)); + struct tracefs_inode *ti = get_tracefs(inode); + unsigned long flags; + + spin_lock_irqsave(&tracefs_inode_lock, flags); + list_del_rcu(&ti->list); + spin_unlock_irqrestore(&tracefs_inode_lock, flags); + + call_rcu(&ti->rcu, tracefs_free_inode_rcu); } static ssize_t default_read_file(struct file *file, char __user *buf, @@ -313,6 +340,8 @@ 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; + struct tracefs_inode *ti; + bool update_uid, update_gid; umode_t tmp_mode; /* @@ -332,6 +361,25 @@ static int tracefs_apply_options(struct super_block *sb, bool remount) if (!remount || opts->opts & BIT(Opt_gid)) inode->i_gid = opts->gid; + if (remount && (opts->opts & BIT(Opt_uid) || opts->opts & BIT(Opt_gid))) { + + update_uid = opts->opts & BIT(Opt_uid); + update_gid = opts->opts & BIT(Opt_gid); + + rcu_read_lock(); + list_for_each_entry_rcu(ti, &tracefs_inodes, list) { + if (update_uid) + ti->flags &= ~TRACEFS_UID_PERM_SET; + + if (update_gid) + ti->flags &= ~TRACEFS_GID_PERM_SET; + + if (ti->flags & TRACEFS_EVENT_INODE) + eventfs_remount(ti, update_uid, update_gid); + } + rcu_read_unlock(); + } + return 0; } @@ -398,7 +446,22 @@ static int tracefs_d_revalidate(struct dentry *dentry, unsigned int flags) return !(ei && ei->is_freed); } +static void tracefs_d_iput(struct dentry *dentry, struct inode *inode) +{ + struct tracefs_inode *ti = get_tracefs(inode); + + /* + * This inode is being freed and cannot be used for + * eventfs. Clear the flag so that it doesn't call into + * eventfs during the remount flag updates. The eventfs_inode + * gets freed after an RCU cycle, so the content will still + * be safe if the iteration is going on now. + */ + ti->flags &= ~TRACEFS_EVENT_INODE; +} + static const struct dentry_operations tracefs_dentry_operations = { + .d_iput = tracefs_d_iput, .d_revalidate = tracefs_d_revalidate, .d_release = tracefs_d_release, }; diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 15c26f9aaad4..29f0c999975b 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -11,8 +11,12 @@ enum { }; struct tracefs_inode { - struct inode vfs_inode; + union { + struct inode vfs_inode; + struct rcu_head rcu; + }; /* The below gets initialized with memset_after(ti, 0, vfs_inode) */ + struct list_head list; unsigned long flags; void *private; }; @@ -73,6 +77,7 @@ struct dentry *tracefs_end_creating(struct dentry *dentry); struct dentry *tracefs_failed_creating(struct dentry *dentry); struct inode *tracefs_get_inode(struct super_block *sb); +void eventfs_remount(struct tracefs_inode *ti, bool update_uid, bool update_gid); void eventfs_d_release(struct dentry *dentry); #endif /* _TRACEFS_INTERNAL_H */ -- 2.43.0

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[for-linus][PATCH 4/9] eventfs: Free all of the eventfs_inode after RCU

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> The freeing of eventfs_inode via a kfree_rcu() callback. But the content of the eventfs_inode was being freed after the last kref. This is dangerous, as changes are being made that can access the content of an eventfs_inode from an RCU loop. Instead of using kfree_rcu() use call_rcu() that calls a function to do all the freeing of the eventfs_inode after a RCU grace period has expired. Link: https://lore.kernel.org/linux-trace-kernel/20240502200905.370261163@goodmis… Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Cc: Andrew Morton <akpm(a)linux-foundation.org> Fixes: 43aa6f97c2d03 ("eventfs: Get rid of dentry pointers without refcounts") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- fs/tracefs/event_inode.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index f5510e26f0f6..cc8b838bbe62 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -73,6 +73,21 @@ enum { #define EVENTFS_MODE_MASK (EVENTFS_SAVE_MODE - 1) +static void free_ei_rcu(struct rcu_head *rcu) +{ + struct eventfs_inode *ei = container_of(rcu, struct eventfs_inode, rcu); + struct eventfs_root_inode *rei; + + kfree(ei->entry_attrs); + kfree_const(ei->name); + if (ei->is_events) { + rei = get_root_inode(ei); + kfree(rei); + } else { + kfree(ei); + } +} + /* * eventfs_inode reference count management. * @@ -85,7 +100,6 @@ static void release_ei(struct kref *ref) { struct eventfs_inode *ei = container_of(ref, struct eventfs_inode, kref); const struct eventfs_entry *entry; - struct eventfs_root_inode *rei; WARN_ON_ONCE(!ei->is_freed); @@ -95,14 +109,7 @@ static void release_ei(struct kref *ref) entry->release(entry->name, ei->data); } - kfree(ei->entry_attrs); - kfree_const(ei->name); - if (ei->is_events) { - rei = get_root_inode(ei); - kfree_rcu(rei, ei.rcu); - } else { - kfree_rcu(ei, rcu); - } + call_rcu(&ei->rcu, free_ei_rcu); } static inline void put_ei(struct eventfs_inode *ei) -- 2.43.0

1 year, 1 month

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[for-linus][PATCH 3/9] eventfs/tracing: Add callback for release of an eventfs_inode

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> Synthetic events create and destroy tracefs files when they are created and removed. The tracing subsystem has its own file descriptor representing the state of the events attached to the tracefs files. There's a race between the eventfs files and this file descriptor of the tracing system where the following can cause an issue: With two scripts 'A' and 'B' doing: Script 'A': echo "hello int aaa" > /sys/kernel/tracing/synthetic_events while : do echo 0 > /sys/kernel/tracing/events/synthetic/hello/enable done Script 'B': echo > /sys/kernel/tracing/synthetic_events Script 'A' creates a synthetic event "hello" and then just writes zero into its enable file. Script 'B' removes all synthetic events (including the newly created "hello" event). What happens is that the opening of the "enable" file has: { struct trace_event_file *file = inode->i_private; int ret; ret = tracing_check_open_get_tr(file->tr); [..] But deleting the events frees the "file" descriptor, and a "use after free" happens with the dereference at "file->tr". The file descriptor does have a reference counter, but there needs to be a way to decrement it from the eventfs when the eventfs_inode is removed that represents this file descriptor. Add an optional "release" callback to the eventfs_entry array structure, that gets called when the eventfs file is about to be removed. This allows for the creating on the eventfs file to increment the tracing file descriptor ref counter. When the eventfs file is deleted, it can call the release function that will call the put function for the tracing file descriptor. This will protect the tracing file from being freed while a eventfs file that references it is being opened. Link: https://lore.kernel.org/linux-trace-kernel/20240426073410.17154-1-Tze-nan.W… Link: https://lore.kernel.org/linux-trace-kernel/20240502090315.448cba46@gandalf.… Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Fixes: 5790b1fb3d672 ("eventfs: Remove eventfs_file and just use eventfs_inode") Reported-by: Tze-nan wu <Tze-nan.Wu(a)mediatek.com> Tested-by: Tze-nan Wu (吳澤南) <Tze-nan.Wu(a)mediatek.com> Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- fs/tracefs/event_inode.c | 23 +++++++++++++++++++++-- include/linux/tracefs.h | 3 +++ kernel/trace/trace_events.c | 12 ++++++++++++ 3 files changed, 36 insertions(+), 2 deletions(-) diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 894c6ca1e500..f5510e26f0f6 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -84,10 +84,17 @@ enum { static void release_ei(struct kref *ref) { struct eventfs_inode *ei = container_of(ref, struct eventfs_inode, kref); + const struct eventfs_entry *entry; struct eventfs_root_inode *rei; WARN_ON_ONCE(!ei->is_freed); + for (int i = 0; i < ei->nr_entries; i++) { + entry = &ei->entries[i]; + if (entry->release) + entry->release(entry->name, ei->data); + } + kfree(ei->entry_attrs); kfree_const(ei->name); if (ei->is_events) { @@ -112,6 +119,18 @@ static inline void free_ei(struct eventfs_inode *ei) } } +/* + * Called when creation of an ei fails, do not call release() functions. + */ +static inline void cleanup_ei(struct eventfs_inode *ei) +{ + if (ei) { + /* Set nr_entries to 0 to prevent release() function being called */ + ei->nr_entries = 0; + free_ei(ei); + } +} + static inline struct eventfs_inode *get_ei(struct eventfs_inode *ei) { if (ei) @@ -734,7 +753,7 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode /* Was the parent freed? */ if (list_empty(&ei->list)) { - free_ei(ei); + cleanup_ei(ei); ei = NULL; } return ei; @@ -835,7 +854,7 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry return ei; fail: - free_ei(ei); + cleanup_ei(ei); tracefs_failed_creating(dentry); return ERR_PTR(-ENOMEM); } diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h index 7a5fe17b6bf9..d03f74658716 100644 --- a/include/linux/tracefs.h +++ b/include/linux/tracefs.h @@ -62,6 +62,8 @@ struct eventfs_file; typedef int (*eventfs_callback)(const char *name, umode_t *mode, void **data, const struct file_operations **fops); +typedef void (*eventfs_release)(const char *name, void *data); + /** * struct eventfs_entry - dynamically created eventfs file call back handler * @name: Then name of the dynamic file in an eventfs directory @@ -72,6 +74,7 @@ typedef int (*eventfs_callback)(const char *name, umode_t *mode, void **data, struct eventfs_entry { const char *name; eventfs_callback callback; + eventfs_release release; }; struct eventfs_inode; diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 52f75c36bbca..6ef29eba90ce 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -2552,6 +2552,14 @@ static int event_callback(const char *name, umode_t *mode, void **data, return 0; } +/* The file is incremented on creation and freeing the enable file decrements it */ +static void event_release(const char *name, void *data) +{ + struct trace_event_file *file = data; + + event_file_put(file); +} + static int event_create_dir(struct eventfs_inode *parent, struct trace_event_file *file) { @@ -2566,6 +2574,7 @@ event_create_dir(struct eventfs_inode *parent, struct trace_event_file *file) { .name = "enable", .callback = event_callback, + .release = event_release, }, { .name = "filter", @@ -2634,6 +2643,9 @@ event_create_dir(struct eventfs_inode *parent, struct trace_event_file *file) return ret; } + /* Gets decremented on freeing of the "enable" file */ + event_file_get(file); + return 0; } -- 2.43.0

1 year, 1 month

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[PATCH] stackleak: don't modify ctl_table argument

by Thomas Weißschuh

Sysctl handlers are not supposed to modify the ctl_table passed to them. Adapt the logic to work with a temporary variable, similar to how it is done in other parts of the kernel. This is also a prerequisite to enforce the immutability of the argument through the callbacks prototy. Fixes: 964c9dff0091 ("stackleak: Allow runtime disabling of kernel stack erasing") Cc: stable(a)vger.kernel.org Acked-by: Kees Cook <keescook(a)chromium.org> Reviewed-by: Luis Chamberlain <mcgrof(a)kernel.org> Signed-off-by: Thomas Weißschuh <linux(a)weissschuh.net> --- This was split out of my sysctl-const-handler series [0]. As that series will take some more time, submit the patch on its own, as it is a generic bugfix that is valuable on its own. And I can get it out of my books. Changelog in contrast to the patch in the series: * Reword commit message to remove strong relation to the constification * Cc stable [0] https://lore.kernel.org/lkml/20240423-sysctl-const-handler-v3-0-e0beccb836e… Cc: Joel Granados <j.granados(a)samsung.com> --- kernel/stackleak.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/stackleak.c b/kernel/stackleak.c index 34c9d81eea94..b292e5ca0b7d 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -27,10 +27,11 @@ static int stack_erasing_sysctl(struct ctl_table *table, int write, int ret = 0; int state = !static_branch_unlikely(&stack_erasing_bypass); int prev_state = state; + struct ctl_table tmp = *table; - table->data = &state; - table->maxlen = sizeof(int); - ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + tmp.data = &state; + tmp.maxlen = sizeof(int); + ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); state = !!state; if (ret || !write || state == prev_state) return ret; --- base-commit: f03359bca01bf4372cf2c118cd9a987a5951b1c8 change-id: 20240503-sysctl-const-stackleak-af3e67bc65b0 Best regards, -- Thomas Weißschuh <linux(a)weissschuh.net>

1 year, 1 month

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[PATCH 1/4] PCI: shpchp: bail out if pci_hp_add_bridge() fails

by Nam Cao

If there is no bus number available for the downstream bus of the hot-plugged bridge, pci_hp_add_bridge() will fail. The driver proceeds regardless, and the kernel crashes. Abort if pci_hp_add_bridge() fails. Fixes: 7d01f70ac6f4 ("PCI: shpchp: use generic pci_hp_add_bridge()") Signed-off-by: Nam Cao <namcao(a)linutronix.de> Cc: Yinghai Lu <yinghai(a)kernel.org> Cc: <stable(a)vger.kernel.org> --- drivers/pci/hotplug/shpchp_pci.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/pci/hotplug/shpchp_pci.c b/drivers/pci/hotplug/shpchp_pci.c index 36db0c3c4ea6..2ac98bdc83d9 100644 --- a/drivers/pci/hotplug/shpchp_pci.c +++ b/drivers/pci/hotplug/shpchp_pci.c @@ -48,8 +48,13 @@ int shpchp_configure_device(struct slot *p_slot) } for_each_pci_bridge(dev, parent) { - if (PCI_SLOT(dev->devfn) == p_slot->device) - pci_hp_add_bridge(dev); + if (PCI_SLOT(dev->devfn) == p_slot->device) { + if (pci_hp_add_bridge(dev)) { + pci_stop_and_remove_bus_device(dev); + ret = -EINVAL; + goto out; + } + } } pci_assign_unassigned_bridge_resources(bridge); -- 2.39.2

1 year, 1 month

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Re: Patch "wifi: nl80211: don't free NULL coalescing rule" has been added to the 6.8-stable tree

by Johannes Berg

On Fri, 2024-05-03 at 12:38 -0400, Sasha Levin wrote: > This is a note to let you know that I've just added the patch titled > > wifi: nl80211: don't free NULL coalescing rule > > to the 6.8-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… I was sure I pointed out before (to Greg?) that I made a mistake on this patch and it should be dropped. Anyway, please drop this from _all_ stable kernels. It's obviously bogus. johannes

1 year, 1 month

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