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author | Al Viro <viro@zeniv.linux.org.uk> | 2011-02-16 20:08:54 (GMT) |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2011-03-14 13:15:23 (GMT) |
commit | 15a9155fe3e8215c02b80df51ec2cac7c0d726ad (patch) | |
tree | 8336c506ffd9968678b906a10d625330aaaa83b3 /kernel | |
parent | 586ce098a23b6ab7383df853a84ae3d48dc889aa (diff) | |
download | linux-fsl-qoriq-15a9155fe3e8215c02b80df51ec2cac7c0d726ad.tar.xz |
fix race in audit_get_nd()
don't rely on pathname resolution ending up twice at the same point...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/audit_watch.c | 85 |
1 files changed, 32 insertions, 53 deletions
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c index d2e3c78..20b9fe6 100644 --- a/kernel/audit_watch.c +++ b/kernel/audit_watch.c @@ -144,9 +144,9 @@ int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev) } /* Initialize a parent watch entry. */ -static struct audit_parent *audit_init_parent(struct nameidata *ndp) +static struct audit_parent *audit_init_parent(struct path *path) { - struct inode *inode = ndp->path.dentry->d_inode; + struct inode *inode = path->dentry->d_inode; struct audit_parent *parent; int ret; @@ -353,53 +353,40 @@ static void audit_remove_parent_watches(struct audit_parent *parent) } /* Get path information necessary for adding watches. */ -static int audit_get_nd(char *path, struct nameidata **ndp, struct nameidata **ndw) +static int audit_get_nd(struct audit_watch *watch, struct path *parent) { - struct nameidata *ndparent, *ndwatch; + struct nameidata nd; + struct dentry *d; int err; - ndparent = kmalloc(sizeof(*ndparent), GFP_KERNEL); - if (unlikely(!ndparent)) - return -ENOMEM; + err = path_lookup(watch->path, LOOKUP_PARENT, &nd); + if (err) + return err; - ndwatch = kmalloc(sizeof(*ndwatch), GFP_KERNEL); - if (unlikely(!ndwatch)) { - kfree(ndparent); - return -ENOMEM; + if (nd.last_type != LAST_NORM) { + path_put(&nd.path); + return -EINVAL; } - err = path_lookup(path, LOOKUP_PARENT, ndparent); - if (err) { - kfree(ndparent); - kfree(ndwatch); - return err; + mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); + d = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len); + if (IS_ERR(d)) { + mutex_unlock(&nd.path.dentry->d_inode->i_mutex); + path_put(&nd.path); + return PTR_ERR(d); } - - err = path_lookup(path, 0, ndwatch); - if (err) { - kfree(ndwatch); - ndwatch = NULL; + if (d->d_inode) { + /* update watch filter fields */ + watch->dev = d->d_inode->i_sb->s_dev; + watch->ino = d->d_inode->i_ino; } + mutex_unlock(&nd.path.dentry->d_inode->i_mutex); - *ndp = ndparent; - *ndw = ndwatch; - + *parent = nd.path; + dput(d); return 0; } -/* Release resources used for watch path information. */ -static void audit_put_nd(struct nameidata *ndp, struct nameidata *ndw) -{ - if (ndp) { - path_put(&ndp->path); - kfree(ndp); - } - if (ndw) { - path_put(&ndw->path); - kfree(ndw); - } -} - /* Associate the given rule with an existing parent. * Caller must hold audit_filter_mutex. */ static void audit_add_to_parent(struct audit_krule *krule, @@ -440,31 +427,24 @@ int audit_add_watch(struct audit_krule *krule, struct list_head **list) { struct audit_watch *watch = krule->watch; struct audit_parent *parent; - struct nameidata *ndp = NULL, *ndw = NULL; + struct path parent_path; int h, ret = 0; mutex_unlock(&audit_filter_mutex); /* Avoid calling path_lookup under audit_filter_mutex. */ - ret = audit_get_nd(watch->path, &ndp, &ndw); - if (ret) { - /* caller expects mutex locked */ - mutex_lock(&audit_filter_mutex); - goto error; - } + ret = audit_get_nd(watch, &parent_path); + /* caller expects mutex locked */ mutex_lock(&audit_filter_mutex); - /* update watch filter fields */ - if (ndw) { - watch->dev = ndw->path.dentry->d_inode->i_sb->s_dev; - watch->ino = ndw->path.dentry->d_inode->i_ino; - } + if (ret) + return ret; /* either find an old parent or attach a new one */ - parent = audit_find_parent(ndp->path.dentry->d_inode); + parent = audit_find_parent(parent_path.dentry->d_inode); if (!parent) { - parent = audit_init_parent(ndp); + parent = audit_init_parent(&parent_path); if (IS_ERR(parent)) { ret = PTR_ERR(parent); goto error; @@ -479,9 +459,8 @@ int audit_add_watch(struct audit_krule *krule, struct list_head **list) h = audit_hash_ino((u32)watch->ino); *list = &audit_inode_hash[h]; error: - audit_put_nd(ndp, ndw); /* NULL args OK */ + path_put(&parent_path); return ret; - } void audit_remove_watch_rule(struct audit_krule *krule) |