audit: allow audit code to satisfy getname requests from its names_list

Currently, if we call getname() on a userland string more than once,
we'll get multiple copies of the string and multiple audit_names
records.

Add a function that will allow the audit_names code to satisfy getname
requests using info from the audit_names list, avoiding a new allocation
and audit_names records.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namei.c b/fs/namei.c
index ec638d27642f2016cd354dd0972022f46ee92728..5dbc3f83693476396deccfd7d182ef04555f1f81 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -130,6 +130,10 @@ getname_flags(const char __user *filename, int flags, int *empty)
        char *kname;
        int len;
 
+       result = audit_reusename(filename);
+       if (result)
+               return result;
+
        /* FIXME: create dedicated slabcache? */
        result = kzalloc(sizeof(*result), GFP_KERNEL);
        if (unlikely(!result))

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 7ab2898a8e52d4d4315ffad4007e13d7f2edd837..eaaccff374c6e668f08b44e6244a94f86e2f6adf 100644 (file)
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -471,6 +471,7 @@ extern void __audit_syscall_entry(int arch,
                                  int major, unsigned long a0, unsigned long a1,
                                  unsigned long a2, unsigned long a3);
 extern void __audit_syscall_exit(int ret_success, long ret_value);
+extern struct filename *__audit_reusename(const __user char *uptr);
 extern void __audit_getname(struct filename *name);
 extern void audit_putname(struct filename *name);
 extern void __audit_inode(const char *name, const struct dentry *dentry,
@@ -507,6 +508,12 @@ static inline void audit_syscall_exit(void *pt_regs)
                __audit_syscall_exit(success, return_code);
        }
 }
+static inline struct filename *audit_reusename(const __user char *name)
+{
+       if (unlikely(!audit_dummy_context()))
+               return __audit_reusename(name);
+       return NULL;
+}
 static inline void audit_getname(struct filename *name)
 {
        if (unlikely(!audit_dummy_context()))
@@ -665,6 +672,10 @@ static inline int audit_dummy_context(void)
 {
        return 1;
 }
+static inline struct filename *audit_reusename(const __user char *name)
+{
+       return NULL;
+}
 static inline void audit_getname(struct filename *name)
 { }
 static inline void audit_putname(struct filename *name)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index d4d82319eed58264410c0669bd7efc7a2fd31ff4..521163a5d65f2eb534d1f46f6b8812f4b673f5bb 100644 (file)
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2020,6 +2020,29 @@ static struct audit_names *audit_alloc_name(struct audit_context *context,
        return aname;
 }
 
+/**
+ * audit_reusename - fill out filename with info from existing entry
+ * @uptr: userland ptr to pathname
+ *
+ * Search the audit_names list for the current audit context. If there is an
+ * existing entry with a matching "uptr" then return the filename
+ * associated with that audit_name. If not, return NULL.
+ */
+struct filename *
+__audit_reusename(const __user char *uptr)
+{
+       struct audit_context *context = current->audit_context;
+       struct audit_names *n;
+
+       list_for_each_entry(n, &context->names_list, list) {
+               if (!n->name)
+                       continue;
+               if (n->name->uptr == uptr)
+                       return n->name;
+       }
+       return NULL;
+}
+
 /**
  * audit_getname - add a name to the list
  * @name: name to add