Add gosec linter (#1342)

This PR adds `gosec` linter with the following checks disabled:

- G102: Bind to all interfaces
- G107: Url provided to HTTP request as taint input
- G112: Potential slowloris attack
- G114: Use of net/http serve function that has no support for setting timeouts
- G204: Audit use of command execution
- G401: Detect the usage of DES, RC4, MD5 or SHA1
- G402: Look for bad TLS connection settings
- G404: Insecure random number source (rand)
- G501: Import blocklist: crypto/md5
- G505: Import blocklist: crypto/sha1

We have complaints related to the checks above. They have to be addressed separately.

client/firewall/uspfilter/uspfilter.go

@@ -355,14 +355,16 @@ func (m *Manager) RemovePacketHook(hookID string) error {
 	for _, arr := range m.incomingRules {
 		for _, r := range arr {
 			if r.id == hookID {
-				return m.DeleteRule(&r)
+				rule := r
+				return m.DeleteRule(&rule)
 			}
 		}
 	}
 	for _, arr := range m.outgoingRules {
 		for _, r := range arr {
 			if r.id == hookID {
-				return m.DeleteRule(&r)
+				rule := r
+				return m.DeleteRule(&rule)
 			}
 		}
 	}

client/internal/routemanager/systemops_linux.go

@@ -107,7 +107,8 @@ loop:
 			break loop
 		case syscall.RTM_NEWROUTE:
 			rt := (*routeInfoInMemory)(unsafe.Pointer(&m.Data[0]))
-			attrs, err := syscall.ParseNetlinkRouteAttr(&m)
+			msg := m
+			attrs, err := syscall.ParseNetlinkRouteAttr(&msg)
 			if err != nil {
 				return nil, err
 			}
@@ -146,5 +147,5 @@ func enableIPForwarding() error {
 		return nil
 	}
 
-	return os.WriteFile(ipv4ForwardingPath, []byte("1"), 0644)
+	return os.WriteFile(ipv4ForwardingPath, []byte("1"), 0644) //nolint:gosec
 }

client/ui/client_ui.go

@@ -634,5 +634,5 @@ func checkPIDFile() error {
 		}
 	}
 
-	return os.WriteFile(pidFile, []byte(fmt.Sprintf("%d", os.Getpid())), 0o664)
+	return os.WriteFile(pidFile, []byte(fmt.Sprintf("%d", os.Getpid())), 0o664) //nolint:gosec
 }