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authorJan Kara <jack@suse.cz>2017-07-20 15:08:21 +0200
committerTakashi Iwai <tiwai@suse.de>2017-07-27 17:07:08 +0200
commitb005b4a708b309b266b01a1224178798c320708d (patch)
treef30806bb9573b73f6e95b2fe4ff9805b579049f8
parentff49c29d2206ead8339af9653907b734ea502dca (diff)
dentry name snapshots (CVE-2017-7533 bsc#1049483).rpm-4.4.74-92.32
-rw-r--r--fs/dcache.c27
-rw-r--r--fs/debugfs/inode.c10
-rw-r--r--fs/namei.c8
-rw-r--r--fs/notify/fsnotify.c8
-rw-r--r--include/linux/dcache.h6
-rw-r--r--include/linux/fsnotify.h31
6 files changed, 48 insertions, 42 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 94db85201a0c..b9efb640a165 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -271,6 +271,33 @@ static inline int dname_external(const struct dentry *dentry)
return dentry->d_name.name != dentry->d_iname;
}
+void take_dentry_name_snapshot(struct name_snapshot *name, struct dentry *dentry)
+{
+ spin_lock(&dentry->d_lock);
+ if (unlikely(dname_external(dentry))) {
+ struct external_name *p = external_name(dentry);
+ atomic_inc(&p->u.count);
+ spin_unlock(&dentry->d_lock);
+ name->name = p->name;
+ } else {
+ memcpy(name->inline_name, dentry->d_iname, DNAME_INLINE_LEN);
+ spin_unlock(&dentry->d_lock);
+ name->name = name->inline_name;
+ }
+}
+EXPORT_SYMBOL(take_dentry_name_snapshot);
+
+void release_dentry_name_snapshot(struct name_snapshot *name)
+{
+ if (unlikely(name->name != name->inline_name)) {
+ struct external_name *p;
+ p = container_of(name->name, struct external_name, name[0]);
+ if (unlikely(atomic_dec_and_test(&p->u.count)))
+ kfree_rcu(p, u.head);
+ }
+}
+EXPORT_SYMBOL(release_dentry_name_snapshot);
+
static inline void __d_set_inode_and_type(struct dentry *dentry,
struct inode *inode,
unsigned type_flags)
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 0f5d05bf2131..e49ba072bd64 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -669,7 +669,7 @@ struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
{
int error;
struct dentry *dentry = NULL, *trap;
- const char *old_name;
+ struct name_snapshot old_name;
trap = lock_rename(new_dir, old_dir);
/* Source or destination directories don't exist? */
@@ -684,19 +684,19 @@ struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
goto exit;
- old_name = fsnotify_oldname_init(old_dentry->d_name.name);
+ take_dentry_name_snapshot(&old_name, old_dentry);
error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
dentry);
if (error) {
- fsnotify_oldname_free(old_name);
+ release_dentry_name_snapshot(&old_name);
goto exit;
}
d_move(old_dentry, dentry);
- fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name,
+ fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name.name,
d_is_dir(old_dentry),
NULL, old_dentry);
- fsnotify_oldname_free(old_name);
+ release_dentry_name_snapshot(&old_name);
unlock_rename(new_dir, old_dir);
dput(dentry);
return old_dentry;
diff --git a/fs/namei.c b/fs/namei.c
index 0b0acba72a71..3f96ae087488 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4179,11 +4179,11 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
{
int error;
bool is_dir = d_is_dir(old_dentry);
- const unsigned char *old_name;
struct inode *source = old_dentry->d_inode;
struct inode *target = new_dentry->d_inode;
bool new_is_dir = false;
unsigned max_links = new_dir->i_sb->s_max_links;
+ struct name_snapshot old_name;
/*
* Check source == target.
@@ -4237,7 +4237,7 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
if (error)
return error;
- old_name = fsnotify_oldname_init(old_dentry->d_name.name);
+ take_dentry_name_snapshot(&old_name, old_dentry);
dget(new_dentry);
if (!is_dir || (flags & RENAME_EXCHANGE))
lock_two_nondirectories(source, target);
@@ -4298,14 +4298,14 @@ out:
mutex_unlock(&target->i_mutex);
dput(new_dentry);
if (!error) {
- fsnotify_move(old_dir, new_dir, old_name, is_dir,
+ fsnotify_move(old_dir, new_dir, old_name.name, is_dir,
!(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry);
if (flags & RENAME_EXCHANGE) {
fsnotify_move(new_dir, old_dir, old_dentry->d_name.name,
new_is_dir, NULL, new_dentry);
}
}
- fsnotify_oldname_free(old_name);
+ release_dentry_name_snapshot(&old_name);
return error;
}
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index db39de2dd4cb..a64adc2fced9 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -104,16 +104,20 @@ int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
if (unlikely(!fsnotify_inode_watches_children(p_inode)))
__fsnotify_update_child_dentry_flags(p_inode);
else if (p_inode->i_fsnotify_mask & mask) {
+ struct name_snapshot name;
+
/* we are notifying a parent so come up with the new mask which
* specifies these are events which came from a child. */
mask |= FS_EVENT_ON_CHILD;
+ take_dentry_name_snapshot(&name, dentry);
if (path)
ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
- dentry->d_name.name, 0);
+ name.name, 0);
else
ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
- dentry->d_name.name, 0);
+ name.name, 0);
+ release_dentry_name_snapshot(&name);
}
dput(parent);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 8d7151eb6ceb..d516847e0fae 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -615,5 +615,11 @@ static inline struct inode *d_real_inode(struct dentry *dentry)
return d_backing_inode(d_real(dentry));
}
+struct name_snapshot {
+ const char *name;
+ char inline_name[DNAME_INLINE_LEN];
+};
+void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *);
+void release_dentry_name_snapshot(struct name_snapshot *);
#endif /* __LINUX_DCACHE_H */
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 7ee1774edee5..a7789559078b 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -310,35 +310,4 @@ static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
}
}
-#if defined(CONFIG_FSNOTIFY) /* notify helpers */
-
-/*
- * fsnotify_oldname_init - save off the old filename before we change it
- */
-static inline const unsigned char *fsnotify_oldname_init(const unsigned char *name)
-{
- return kstrdup(name, GFP_KERNEL);
-}
-
-/*
- * fsnotify_oldname_free - free the name we got from fsnotify_oldname_init
- */
-static inline void fsnotify_oldname_free(const unsigned char *old_name)
-{
- kfree(old_name);
-}
-
-#else /* CONFIG_FSNOTIFY */
-
-static inline const char *fsnotify_oldname_init(const unsigned char *name)
-{
- return NULL;
-}
-
-static inline void fsnotify_oldname_free(const unsigned char *old_name)
-{
-}
-
-#endif /* CONFIG_FSNOTIFY */
-
#endif /* _LINUX_FS_NOTIFY_H */