debugfs: purge obsolete SRCU based removal protection
Purge the SRCU based file removal race protection in favour of the new,
refcount based debugfs_file_get()/debugfs_file_put() API.
Fixes: 49d200deaa ("debugfs: prevent access to removed files' private data")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Nicolai Stange
Greg Kroah-Hartman
parent
7cda7b8f97
commit
c9afbec270
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@ -22,7 +22,6 @@
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#include <linux/slab.h>
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#include <linux/atomic.h>
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#include <linux/device.h>
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#include <linux/srcu.h>
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#include <asm/poll.h>
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#include "internal.h"
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@ -48,53 +47,6 @@ const struct file_operations debugfs_noop_file_operations = {
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.llseek = noop_llseek,
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};
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/**
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* debugfs_use_file_start - mark the beginning of file data access
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* @dentry: the dentry object whose data is being accessed.
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* @srcu_idx: a pointer to some memory to store a SRCU index in.
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*
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* Up to a matching call to debugfs_use_file_finish(), any
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* successive call into the file removing functions debugfs_remove()
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* and debugfs_remove_recursive() will block. Since associated private
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* file data may only get freed after a successful return of any of
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* the removal functions, you may safely access it after a successful
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* call to debugfs_use_file_start() without worrying about
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* lifetime issues.
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*
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* If -%EIO is returned, the file has already been removed and thus,
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* it is not safe to access any of its data. If, on the other hand,
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* it is allowed to access the file data, zero is returned.
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*
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* Regardless of the return code, any call to
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* debugfs_use_file_start() must be followed by a matching call
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* to debugfs_use_file_finish().
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*/
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int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx)
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__acquires(&debugfs_srcu)
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{
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*srcu_idx = srcu_read_lock(&debugfs_srcu);
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barrier();
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if (d_unlinked(dentry))
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return -EIO;
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return 0;
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}
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EXPORT_SYMBOL_GPL(debugfs_use_file_start);
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/**
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* debugfs_use_file_finish - mark the end of file data access
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* @srcu_idx: the SRCU index "created" by a former call to
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* debugfs_use_file_start().
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*
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* Allow any ongoing concurrent call into debugfs_remove() or
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* debugfs_remove_recursive() blocked by a former call to
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* debugfs_use_file_start() to proceed and return to its caller.
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*/
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void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu)
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{
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srcu_read_unlock(&debugfs_srcu, srcu_idx);
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}
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EXPORT_SYMBOL_GPL(debugfs_use_file_finish);
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#define F_DENTRY(filp) ((filp)->f_path.dentry)
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const struct file_operations *debugfs_real_fops(const struct file *filp)
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@ -27,14 +27,11 @@
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#include <linux/parser.h>
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#include <linux/magic.h>
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#include <linux/slab.h>
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#include <linux/srcu.h>
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#include "internal.h"
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#define DEBUGFS_DEFAULT_MODE 0700
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DEFINE_SRCU(debugfs_srcu);
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static struct vfsmount *debugfs_mount;
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static int debugfs_mount_count;
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static bool debugfs_registered;
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@ -693,8 +690,6 @@ void debugfs_remove(struct dentry *dentry)
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inode_unlock(d_inode(parent));
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if (!ret)
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simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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synchronize_srcu(&debugfs_srcu);
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}
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EXPORT_SYMBOL_GPL(debugfs_remove);
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@ -768,8 +763,6 @@ void debugfs_remove_recursive(struct dentry *dentry)
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if (!__debugfs_remove(child, parent))
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simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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inode_unlock(d_inode(parent));
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synchronize_srcu(&debugfs_srcu);
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}
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EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
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@ -23,7 +23,6 @@
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struct device;
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struct file_operations;
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struct srcu_struct;
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struct debugfs_blob_wrapper {
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void *data;
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@ -43,8 +42,6 @@ struct debugfs_regset32 {
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extern struct dentry *arch_debugfs_dir;
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extern struct srcu_struct debugfs_srcu;
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#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
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static int __fops ## _open(struct inode *inode, struct file *file) \
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{ \
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@ -90,11 +87,6 @@ struct dentry *debugfs_create_automount(const char *name,
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void debugfs_remove(struct dentry *dentry);
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void debugfs_remove_recursive(struct dentry *dentry);
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int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx)
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__acquires(&debugfs_srcu);
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void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu);
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const struct file_operations *debugfs_real_fops(const struct file *filp);
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int debugfs_file_get(struct dentry *dentry);
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@ -227,17 +219,6 @@ static inline void debugfs_remove(struct dentry *dentry)
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static inline void debugfs_remove_recursive(struct dentry *dentry)
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{ }
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static inline int debugfs_use_file_start(const struct dentry *dentry,
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int *srcu_idx)
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__acquires(&debugfs_srcu)
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{
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return 0;
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}
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static inline void debugfs_use_file_finish(int srcu_idx)
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__releases(&debugfs_srcu)
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{ }
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static inline int debugfs_file_get(struct dentry *dentry)
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{
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return 0;
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@ -280,7 +280,6 @@ config PAGE_OWNER
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config DEBUG_FS
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bool "Debug Filesystem"
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select SRCU
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help
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debugfs is a virtual file system that kernel developers use to put
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debugging files into. Enable this option to be able to read and
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