audit: initialize context values in case of mandatory events

Issue ghak120 enabled syscall records to accompany required records when
no rules are present to trigger the storage of syscall context.  A
reported issue showed that the cwd was not always initialized.  That
issue was already resolved, but a review of all other records that could
be triggered at the time of a syscall record revealed other potential
values that could be missing or misleading.  Initialize them.

The fds array is reset to -1 after the first syscall to indicate it
isn't valid any more, but was never set to -1 when the context was
allocated to indicate it wasn't yet valid.

The audit_inode* functions can be called without going through
getname_flags() or getname_kernel() that sets audit_names and cwd, so
set the cwd if it has not already been done so due to audit_names being
valid.

The LSM dump_common_audit_data() LSM_AUDIT_DATA_NET:AF_UNIX case was
missed with the ghak96 patch, so add that case here.

Please see issue linux-audit/audit-kernel#120
Please see issue linux-audit/audit-kernel#96
Passes audit-testsuite.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>

kernel/auditsc.c

@@ -929,6 +929,7 @@ static inline struct audit_context *audit_alloc_context(enum audit_state state)
 	context->prio = state == AUDIT_RECORD_CONTEXT ? ~0ULL : 0;
 	INIT_LIST_HEAD(&context->killed_trees);
 	INIT_LIST_HEAD(&context->names_list);
+	context->fds[0] = -1;
 	return context;
 }
 
@@ -2076,6 +2077,7 @@ void __audit_inode(struct filename *name, const struct dentry *dentry,
 	}
 	handle_path(dentry);
 	audit_copy_inode(n, dentry, inode, flags & AUDIT_INODE_NOEVAL);
+	_audit_getcwd(context);
 }
 
 void __audit_file(const struct file *file)
@@ -2194,6 +2196,7 @@ void __audit_inode_child(struct inode *parent,
 		audit_copy_inode(found_child, dentry, inode, 0);
 	else
 		found_child->ino = AUDIT_INO_UNSET;
+	_audit_getcwd(context);
 }
 EXPORT_SYMBOL_GPL(__audit_inode_child);
 

security/lsm_audit.c

@@ -369,6 +369,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 					audit_log_untrustedstring(ab, p);
 				else
 					audit_log_n_hex(ab, p, len);
+				audit_getcwd();
 				break;
 			}
 		}