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authorJames Morris <jmorris@namei.org>2007-04-26 00:12:05 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2007-04-27 10:57:33 -0700
commit057f6c019fff9ee290641d50647359bb8898918e (patch)
treec051a915e2038825dd2f50f24fc28abb3c4a5e79 /fs
parent523ded71de0c5e66973335bf99a80edfda9f401b (diff)
security: prevent permission checking of file removal via sysfs_remove_group()
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>
Diffstat (limited to 'fs')
-rw-r--r--fs/namei.c72
-rw-r--r--fs/sysfs/group.c6
2 files changed, 56 insertions, 22 deletions
diff --git a/fs/namei.c b/fs/namei.c
index ee60cc4d345..880052cadbc 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 b20951c9376..52eed2a7a5e 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);