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From: Greg Kroah-Hartman <gregkh@suse.de>
To: linux-kernel@vger.kernel.org
Cc: James Morris <jmorris@namei.org>,
	Nagendra Singh Tomar <nagendra_tomar@adaptec.com>,
	Tejun Heo <htejun@gmail.com>, Stephen Smalley <sds@tycho.nsa.gov>,
	Eric Paris <eparis@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@suse.de>
Subject: [PATCH 41/46] security: prevent permission checking of file removal via sysfs_remove_group()
Date: Fri, 27 Apr 2007 11:53:55 -0700	[thread overview]
Message-ID: <11777001931075-git-send-email-gregkh@suse.de> (raw)
In-Reply-To: <11777001891914-git-send-email-gregkh@suse.de>

From: James Morris <jmorris@namei.org>

Prevent permission checking from being performed when the kernel wants to
unconditionally remove a sysfs group, by introducing an kernel-only variant
of lookup_one_len(), lookup_one_len_kern().

Additionally, as sysfs_remove_group() does not check the return value of
the lookup before using it, a BUG_ON has been added to pinpoint the cause
of any problems potentially caused by this (and as a form of annotation).

Signed-off-by: James Morris <jmorris@namei.org>
Cc: Nagendra Singh Tomar <nagendra_tomar@adaptec.com>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 fs/namei.c            |   72 +++++++++++++++++++++++++++++++++++-------------
 fs/sysfs/group.c      |    6 +++-
 include/linux/namei.h |    1 +
 3 files changed, 57 insertions(+), 22 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index ee60cc4..880052c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1243,22 +1243,13 @@ int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags,
 	return err;
 }
 
-/*
- * Restricted form of lookup. Doesn't follow links, single-component only,
- * needs parent already locked. Doesn't follow mounts.
- * SMP-safe.
- */
-static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd)
+static inline struct dentry *__lookup_hash_kern(struct qstr *name, struct dentry *base, struct nameidata *nd)
 {
-	struct dentry * dentry;
+	struct dentry *dentry;
 	struct inode *inode;
 	int err;
 
 	inode = base->d_inode;
-	err = permission(inode, MAY_EXEC, nd);
-	dentry = ERR_PTR(err);
-	if (err)
-		goto out;
 
 	/*
 	 * See if the low-level filesystem might want
@@ -1287,35 +1278,76 @@ out:
 	return dentry;
 }
 
+/*
+ * Restricted form of lookup. Doesn't follow links, single-component only,
+ * needs parent already locked. Doesn't follow mounts.
+ * SMP-safe.
+ */
+static inline struct dentry * __lookup_hash(struct qstr *name, struct dentry *base, struct nameidata *nd)
+{
+	struct dentry *dentry;
+	struct inode *inode;
+	int err;
+
+	inode = base->d_inode;
+
+	err = permission(inode, MAY_EXEC, nd);
+	dentry = ERR_PTR(err);
+	if (err)
+		goto out;
+
+	dentry = __lookup_hash_kern(name, base, nd);
+out:
+	return dentry;
+}
+
 static struct dentry *lookup_hash(struct nameidata *nd)
 {
 	return __lookup_hash(&nd->last, nd->dentry, nd);
 }
 
 /* SMP-safe */
-struct dentry * lookup_one_len(const char * name, struct dentry * base, int len)
+static inline int __lookup_one_len(const char *name, struct qstr *this, struct dentry *base, int len)
 {
 	unsigned long hash;
-	struct qstr this;
 	unsigned int c;
 
-	this.name = name;
-	this.len = len;
+	this->name = name;
+	this->len = len;
 	if (!len)
-		goto access;
+		return -EACCES;
 
 	hash = init_name_hash();
 	while (len--) {
 		c = *(const unsigned char *)name++;
 		if (c == '/' || c == '\0')
-			goto access;
+			return -EACCES;
 		hash = partial_name_hash(c, hash);
 	}
-	this.hash = end_name_hash(hash);
+	this->hash = end_name_hash(hash);
+	return 0;
+}
 
+struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
+{
+	int err;
+	struct qstr this;
+
+	err = __lookup_one_len(name, &this, base, len);
+	if (err)
+		return ERR_PTR(err);
 	return __lookup_hash(&this, base, NULL);
-access:
-	return ERR_PTR(-EACCES);
+}
+
+struct dentry *lookup_one_len_kern(const char *name, struct dentry *base, int len)
+{
+	int err;
+	struct qstr this;
+
+	err = __lookup_one_len(name, &this, base, len);
+	if (err)
+		return ERR_PTR(err);
+	return __lookup_hash_kern(&this, base, NULL);
 }
 
 /*
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index b20951c..52eed2a 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -70,9 +70,11 @@ void sysfs_remove_group(struct kobject * kobj,
 {
 	struct dentry * dir;
 
-	if (grp->name)
-		dir = lookup_one_len(grp->name, kobj->dentry,
+	if (grp->name) {
+		dir = lookup_one_len_kern(grp->name, kobj->dentry,
 				strlen(grp->name));
+		BUG_ON(IS_ERR(dir));
+	}
 	else
 		dir = dget(kobj->dentry);
 
diff --git a/include/linux/namei.h b/include/linux/namei.h
index d39a5a6..b7dd249 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -82,6 +82,7 @@ extern struct file *nameidata_to_filp(struct nameidata *nd, int flags);
 extern void release_open_intent(struct nameidata *);
 
 extern struct dentry * lookup_one_len(const char *, struct dentry *, int);
+extern struct dentry *lookup_one_len_kern(const char *, struct dentry *, int);
 
 extern int follow_down(struct vfsmount **, struct dentry **);
 extern int follow_up(struct vfsmount **, struct dentry **);
-- 
1.5.1.2


  reply	other threads:[~2007-04-27 19:00 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-27 18:51 [GIT PATCH] Driver core patches for 2.6.21 Greg KH
2007-04-27 18:53 ` [PATCH 01/46] driver core: fix device_add error path Greg Kroah-Hartman
2007-04-27 18:53   ` [PATCH 02/46] driver core: fix namespace issue with devices assigned to classes Greg Kroah-Hartman
2007-04-27 18:53     ` [PATCH 03/46] dev_printk and new-style class devices Greg Kroah-Hartman
     [not found]       ` <11777000511784-git-send-email-gregkh@suse.de>
2007-04-27 18:53         ` [PATCH 05/46] driver core: Use attribute groups in struct device_type Greg Kroah-Hartman
2007-04-27 18:53           ` [PATCH 06/46] Driver core: add name to device_type Greg Kroah-Hartman
2007-04-27 18:53             ` [PATCH 07/46] kobject: kobject_shadow_add cleanup Greg Kroah-Hartman
2007-04-27 18:53               ` [PATCH 08/46] driver core: per-subsystem multithreaded probing Greg Kroah-Hartman
2007-04-27 18:53                 ` [PATCH 09/46] powerpc: make it compile for multithread change Greg Kroah-Hartman
2007-04-27 18:53                   ` [PATCH 10/46] driver core: don't fail attaching the device if it cannot be bound Greg Kroah-Hartman
2007-04-27 18:53                     ` [PATCH 11/46] Driver core: remove unneeded completion from driver release path Greg Kroah-Hartman
2007-04-27 18:53                       ` [PATCH 12/46] kref: fix CPU ordering with respect to krefs Greg Kroah-Hartman
2007-04-27 18:53                         ` [PATCH 13/46] Driver core: notify userspace of network device renames Greg Kroah-Hartman
2007-04-27 18:53                           ` [PATCH 14/46] Driver core: suppress uevents via filter Greg Kroah-Hartman
2007-04-27 18:53                             ` [PATCH 15/46] Driver core: switch firmware_class to uevent_suppress Greg Kroah-Hartman
2007-04-27 18:53                               ` [PATCH 16/46] uevent: use add_uevent_var() instead of open coding it Greg Kroah-Hartman
2007-04-27 18:53                                 ` [PATCH 17/46] Driver core: add suspend() and resume() to struct device_type Greg Kroah-Hartman
2007-04-27 18:53                                   ` [PATCH 18/46] Kobject: kobject_uevent.c: Collapse unnecessary loop nesting (top_kobj) Greg Kroah-Hartman
2007-04-27 18:53                                     ` [PATCH 19/46] kobject: kobject_add() reference leak Greg Kroah-Hartman
2007-04-27 18:53                                       ` [PATCH 20/46] Driver core: remove use of rwsem Greg Kroah-Hartman
2007-04-27 18:53                                         ` [PATCH 21/46] SCSI: use the proper semaphore to protect the class lists Greg Kroah-Hartman
2007-04-27 18:53                                           ` [PATCH 22/46] USB: remove use of the bus rwsem, as it doesn't really protect anything Greg Kroah-Hartman
2007-04-27 18:53                                             ` [PATCH 23/46] PNP: stop using the subsystem rwsem Greg Kroah-Hartman
2007-04-27 18:53                                               ` [PATCH 24/46] Input: serio - do not touch bus's rwsem Greg Kroah-Hartman
2007-04-27 18:53                                                 ` [PATCH 25/46] Input: gameport " Greg Kroah-Hartman
2007-04-27 18:53                                                   ` [PATCH 26/46] IDE: remove rwsem use from ide-proc core Greg Kroah-Hartman
2007-04-27 18:53                                                     ` [PATCH 27/46] IEEE1394: remove rwsem use from ieee1394 core Greg Kroah-Hartman
2007-04-27 18:53                                                       ` [PATCH 28/46] PHY: remove rwsem use from phy core Greg Kroah-Hartman
2007-04-27 18:53                                                         ` [PATCH 29/46] qeth: Remove usage of subsys.rwsem Greg Kroah-Hartman
2007-04-27 18:53                                                           ` [PATCH 30/46] kobject core: remove rwsem from struct subsystem Greg Kroah-Hartman
2007-04-27 18:53                                                             ` [PATCH 31/46] Driver core: make uevent-environment available in uevent-file Greg Kroah-Hartman
2007-04-27 18:53                                                               ` [PATCH 32/46] Driver core: warn when userspace writes to the uevent file in a non-supported way Greg Kroah-Hartman
2007-04-27 18:53                                                                 ` [PATCH 33/46] kobject: Comment and warning fixes to kobject.c Greg Kroah-Hartman
2007-04-27 18:53                                                                   ` [PATCH 34/46] the overdue removal of the mount/umount uevents Greg Kroah-Hartman
2007-04-27 18:53                                                                     ` [PATCH 35/46] debugfs: Add debugfs_create_u64() Greg Kroah-Hartman
2007-04-27 18:53                                                                       ` [PATCH 36/46] driver core: bus_add_driver should return an error if no bus Greg Kroah-Hartman
2007-04-27 18:53                                                                         ` [PATCH 37/46] Driver core: use mutex instead of semaphore in DMA pool handler Greg Kroah-Hartman
2007-04-27 18:53                                                                           ` [PATCH 38/46] sysfs: bin.c printk fix Greg Kroah-Hartman
2007-04-27 18:53                                                                             ` [PATCH 39/46] s390: cio: Delay uevents for subchannels Greg Kroah-Hartman
2007-04-27 18:53                                                                               ` [PATCH 40/46] device_schedule_callback() needs a module reference Greg Kroah-Hartman
2007-04-27 18:53                                                                                 ` Greg Kroah-Hartman [this message]
2007-04-27 18:53                                                                                   ` [PATCH 42/46] define platform wakeup hook, use in pci_enable_wake() Greg Kroah-Hartman
2007-04-27 18:53                                                                                     ` [PATCH 43/46] s2ram: add arch irq disable/enable hooks Greg Kroah-Hartman
2007-04-27 18:53                                                                                       ` [PATCH 44/46] mod_sysfs_setup() doesn't return errno when kobject_add_dir() failure occurs Greg Kroah-Hartman
2007-04-27 18:53                                                                                         ` [PATCH 45/46] drivers/base/attribute_container.c: use mutex instead of binary semaphore Greg Kroah-Hartman
2007-04-27 18:54                                                                                           ` [PATCH 46/46] dev_dbg: check dev_dbg() arguments Greg Kroah-Hartman
2007-04-27 21:11                                                         ` [PATCH 28/46] PHY: remove rwsem use from phy core Andy Fleming
2007-04-27 20:27       ` [PATCH 04/46] Driver core: udev triggered device-driver binding Greg Kroah-Hartman

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