smack: implement logging V3

the following patch, add logging of Smack security decisions.
This is of course very useful to understand what your current smack policy does.
As suggested by Casey, it also now forbids labels with ', " or \

It introduces a '/smack/logging' switch :
0: no logging
1: log denied (default)
2: log accepted
3: log denied&accepted

Signed-off-by: Etienne Basset <etienne.basset@numericable.fr>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

Documentation/Smack.txt

@@ -184,8 +184,9 @@ length. Single character labels using special characters, that being anything
 other than a letter or digit, are reserved for use by the Smack development
 team. Smack labels are unstructured, case sensitive, and the only operation
 ever performed on them is comparison for equality. Smack labels cannot
-contain unprintable characters or the "/" (slash) character. Smack labels
-cannot begin with a '-', which is reserved for special options.
+contain unprintable characters, the "/" (slash), the "\" (backslash), the "'"
+(quote) and '"' (double-quote) characters.
+Smack labels cannot begin with a '-', which is reserved for special options.
 
 There are some predefined labels:
 
@@ -523,3 +524,18 @@ Smack supports some mount options:
 
 These mount options apply to all file system types.
 
+Smack auditing
+
+If you want Smack auditing of security events, you need to set CONFIG_AUDIT
+in your kernel configuration.
+By default, all denied events will be audited. You can change this behavior by
+writing a single character to the /smack/logging file :
+0 : no logging
+1 : log denied (default)
+2 : log accepted
+3 : log denied & accepted
+
+Events are logged as 'key=value' pairs, for each event you at least will get
+the subjet, the object, the rights requested, the action, the kernel function
+that triggered the event, plus other pairs depending on the type of event
+audited.

security/Makefile

@@ -16,6 +16,9 @@ obj-$(CONFIG_SECURITYFS)		+= inode.o
 # Must precede capability.o in order to stack properly.
 obj-$(CONFIG_SECURITY_SELINUX)		+= selinux/built-in.o
 obj-$(CONFIG_SECURITY_SMACK)		+= smack/built-in.o
+ifeq ($(CONFIG_AUDIT),y)
+obj-$(CONFIG_SECURITY_SMACK)		+= lsm_audit.o
+endif
 obj-$(CONFIG_SECURITY_TOMOYO)		+= tomoyo/built-in.o
 obj-$(CONFIG_SECURITY_ROOTPLUG)		+= root_plug.o
 obj-$(CONFIG_CGROUP_DEVICE)		+= device_cgroup.o

security/smack/smack.h

@@ -20,6 +20,7 @@
 #include <net/netlabel.h>
 #include <linux/list.h>
 #include <linux/rculist.h>
+#include <linux/lsm_audit.h>
 
 /*
  * Why 23? CIPSO is constrained to 30, so a 32 byte buffer is
@@ -178,6 +179,20 @@ struct smack_known {
 #define MAY_READWRITE	(MAY_READ | MAY_WRITE)
 #define MAY_NOT		0
 
+/*
+ * Number of access types used by Smack (rwxa)
+ */
+#define SMK_NUM_ACCESS_TYPE 4
+
+/*
+ * Smack audit data; is empty if CONFIG_AUDIT not set
+ * to save some stack
+ */
+struct smk_audit_info {
+#ifdef CONFIG_AUDIT
+	struct common_audit_data a;
+#endif
+};
 /*
  * These functions are in smack_lsm.c
  */
@@ -186,8 +201,8 @@ struct inode_smack *new_inode_smack(char *);
 /*
  * These functions are in smack_access.c
  */
-int smk_access(char *, char *, int);
-int smk_curacc(char *, u32);
+int smk_access(char *, char *, int, struct smk_audit_info *);
+int smk_curacc(char *, u32, struct smk_audit_info *);
 int smack_to_cipso(const char *, struct smack_cipso *);
 void smack_from_cipso(u32, char *, char *);
 char *smack_from_secid(const u32);
@@ -237,4 +252,93 @@ static inline char *smk_of_inode(const struct inode *isp)
 	return sip->smk_inode;
 }
 
+/*
+ * logging functions
+ */
+#define SMACK_AUDIT_DENIED 0x1
+#define SMACK_AUDIT_ACCEPT 0x2
+extern int log_policy;
+
+void smack_log(char *subject_label, char *object_label,
+		int request,
+		int result, struct smk_audit_info *auditdata);
+
+#ifdef CONFIG_AUDIT
+
+/*
+ * some inline functions to set up audit data
+ * they do nothing if CONFIG_AUDIT is not set
+ *
+ */
+static inline void smk_ad_init(struct smk_audit_info *a, const char *func,
+			       char type)
+{
+	memset(a, 0, sizeof(*a));
+	a->a.type = type;
+	a->a.function = func;
+}
+
+static inline void smk_ad_setfield_u_tsk(struct smk_audit_info *a,
+					 struct task_struct *t)
+{
+	a->a.u.tsk = t;
+}
+static inline void smk_ad_setfield_u_fs_path_dentry(struct smk_audit_info *a,
+						    struct dentry *d)
+{
+	a->a.u.fs.path.dentry = d;
+}
+static inline void smk_ad_setfield_u_fs_path_mnt(struct smk_audit_info *a,
+						 struct vfsmount *m)
+{
+	a->a.u.fs.path.mnt = m;
+}
+static inline void smk_ad_setfield_u_fs_inode(struct smk_audit_info *a,
+					      struct inode *i)
+{
+	a->a.u.fs.inode = i;
+}
+static inline void smk_ad_setfield_u_fs_path(struct smk_audit_info *a,
+					     struct path p)
+{
+	a->a.u.fs.path = p;
+}
+static inline void smk_ad_setfield_u_net_sk(struct smk_audit_info *a,
+					    struct sock *sk)
+{
+	a->a.u.net.sk = sk;
+}
+
+#else /* no AUDIT */
+
+static inline void smk_ad_init(struct smk_audit_info *a, const char *func,
+			       char type)
+{
+}
+static inline void smk_ad_setfield_u_tsk(struct smk_audit_info *a,
+					 struct task_struct *t)
+{
+}
+static inline void smk_ad_setfield_u_fs_path_dentry(struct smk_audit_info *a,
+						    struct dentry *d)
+{
+}
+static inline void smk_ad_setfield_u_fs_path_mnt(struct smk_audit_info *a,
+						 struct vfsmount *m)
+{
+}
+static inline void smk_ad_setfield_u_fs_inode(struct smk_audit_info *a,
+					      struct inode *i)
+{
+}
+static inline void smk_ad_setfield_u_fs_path(struct smk_audit_info *a,
+					     struct path p)
+{
+}
+static inline void smk_ad_setfield_u_net_sk(struct smk_audit_info *a,
+					    struct sock *sk)
+{
+}
+#endif
+
 #endif  /* _SECURITY_SMACK_H */