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author | James Morris <jmorris@namei.org> | 2007-04-26 00:12:05 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-04-27 10:57:33 -0700 |
commit | 057f6c019fff9ee290641d50647359bb8898918e (patch) | |
tree | c051a915e2038825dd2f50f24fc28abb3c4a5e79 /fs/namei.c | |
parent | 523ded71de0c5e66973335bf99a80edfda9f401b (diff) | |
download | kernel_samsung_aries-057f6c019fff9ee290641d50647359bb8898918e.zip kernel_samsung_aries-057f6c019fff9ee290641d50647359bb8898918e.tar.gz kernel_samsung_aries-057f6c019fff9ee290641d50647359bb8898918e.tar.bz2 |
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/namei.c')
-rw-r--r-- | fs/namei.c | 72 |
1 files changed, 52 insertions, 20 deletions
@@ -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); } /* |