diff options
Diffstat (limited to 'test/security/k8s/src')
3 files changed, 232 insertions, 205 deletions
diff --git a/test/security/k8s/src/check/validators/master/api/api.go b/test/security/k8s/src/check/validators/master/api/api.go index 1ca920e1a..fc0d04992 100644 --- a/test/security/k8s/src/check/validators/master/api/api.go +++ b/test/security/k8s/src/check/validators/master/api/api.go @@ -2,13 +2,13 @@ package api import ( "strconv" - "strings" + + "check/validators/master/args" + "check/validators/master/boolean" ) const ( portDisabled = 0 - portLowest = 1 - portHighest = 65536 auditLogAge = 30 auditLogBackups = 10 @@ -24,368 +24,234 @@ const ( // IsBasicAuthFileAbsent validates there is no basic authentication file specified. func IsBasicAuthFileAbsent(params []string) bool { - return isFlagAbsent("--basic-auth-file=", params) + return boolean.IsFlagAbsent("--basic-auth-file=", params) } // IsTokenAuthFileAbsent validates there is no token based authentication file specified. func IsTokenAuthFileAbsent(params []string) bool { - return isFlagAbsent("--token-auth-file=", params) + return boolean.IsFlagAbsent("--token-auth-file=", params) } // IsInsecureAllowAnyTokenAbsent validates insecure tokens are not accepted. func IsInsecureAllowAnyTokenAbsent(params []string) bool { - return isFlagAbsent("--insecure-allow-any-token", params) -} - -// isFlagAbsent checks absence of selected flag in parameters. -func isFlagAbsent(flag string, params []string) bool { - found := filterFlags(params, flag) - if len(found) != 0 { - return false - } - return true + return boolean.IsFlagAbsent("--insecure-allow-any-token", params) } // IsAnonymousAuthDisabled validates there is single "--anonymous-auth" flag and it is set to "false". func IsAnonymousAuthDisabled(params []string) bool { - return hasSingleFlagArgument("--anonymous-auth=", "false", params) + return args.HasSingleFlagArgument("--anonymous-auth=", "false", params) } // IsInsecurePortUnbound validates there is single "--insecure-port" flag and it is set to "0" (disabled). func IsInsecurePortUnbound(params []string) bool { - return hasSingleFlagArgument("--insecure-port=", strconv.Itoa(portDisabled), params) + return args.HasSingleFlagArgument("--insecure-port=", strconv.Itoa(portDisabled), params) } // IsProfilingDisabled validates there is single "--profiling" flag and it is set to "false". func IsProfilingDisabled(params []string) bool { - return hasSingleFlagArgument("--profiling=", "false", params) + return args.HasSingleFlagArgument("--profiling=", "false", params) } // IsRepairMalformedUpdatesDisabled validates there is single "--repair-malformed-updates" flag and it is set to "false". func IsRepairMalformedUpdatesDisabled(params []string) bool { - return hasSingleFlagArgument("--repair-malformed-updates=", "false", params) + return args.HasSingleFlagArgument("--repair-malformed-updates=", "false", params) } // IsServiceAccountLookupEnabled validates there is single "--service-account-lookup" flag and it is set to "true". func IsServiceAccountLookupEnabled(params []string) bool { - return hasSingleFlagArgument("--service-account-lookup=", "true", params) + return args.HasSingleFlagArgument("--service-account-lookup=", "true", params) } // IsStrongCryptoCipherInUse validates there is single "--tls-cipher-suites=" flag and it is set to strong crypto ciphers. func IsStrongCryptoCipherInUse(params []string) bool { - return hasSingleFlagArgument("--tls-cipher-suites=", strongCryptoCiphers, params) -} - -// hasSingleFlagArgument checks whether selected flag was used once and has requested argument. -func hasSingleFlagArgument(flag string, argument string, params []string) bool { - found := filterFlags(params, flag) - if len(found) != 1 { - return false - } - - _, value := splitKV(found[0], "=") - if value != argument { - return false - } - return true -} - -// filterFlags returns all occurrences of selected flag. -func filterFlags(strs []string, flag string) []string { - var filtered []string - for _, str := range strs { - if strings.HasPrefix(str, flag) { - filtered = append(filtered, str) - } - } - return filtered -} - -// splitKV splits key and value (after first occurrence of separator). -func splitKV(s, sep string) (string, string) { - ret := strings.SplitN(s, sep, 2) - return ret[0], ret[1] + return args.HasSingleFlagArgument("--tls-cipher-suites=", strongCryptoCiphers, params) } // IsKubeletHTTPSAbsentOrEnabled validates there is single "--kubelet-https" flag and it is set to "true". func IsKubeletHTTPSAbsentOrEnabled(params []string) bool { - return isFlagAbsent("--kubelet-https=", params) || - hasSingleFlagArgument("--kubelet-https=", "true", params) + return boolean.IsFlagAbsent("--kubelet-https=", params) || + args.HasSingleFlagArgument("--kubelet-https=", "true", params) } // IsInsecureBindAddressAbsentOrLoopback validates there is no insecure bind address or it is loopback address. func IsInsecureBindAddressAbsentOrLoopback(params []string) bool { - return isFlagAbsent("--insecure-bind-address=", params) || - hasSingleFlagArgument("--insecure-bind-address=", "127.0.0.1", params) + return boolean.IsFlagAbsent("--insecure-bind-address=", params) || + args.HasSingleFlagArgument("--insecure-bind-address=", "127.0.0.1", params) } // IsSecurePortAbsentOrValid validates there is no secure port set explicitly or it has legal value. func IsSecurePortAbsentOrValid(params []string) bool { - return isFlagAbsent("--secure-port=", params) || - hasFlagValidPort("--secure-port=", params) -} - -// hasFlagValidPort checks whether selected flag has valid port as an argument in given command. -func hasFlagValidPort(flag string, params []string) bool { - found := filterFlags(params, flag) - if len(found) != 1 { - return false - } - - _, value := splitKV(found[0], "=") - port, err := strconv.Atoi(value) // what about empty parameter? - if err != nil { - return false - } - if port < portLowest || port > portHighest { - return false - } - return true + return boolean.IsFlagAbsent("--secure-port=", params) || + args.HasSingleFlagValidPort("--secure-port=", params) } // IsAlwaysAdmitAdmissionControlPluginExcluded validates AlwaysAdmit is excluded from admission control plugins. func IsAlwaysAdmitAdmissionControlPluginExcluded(params []string) bool { - if isSingleFlagPresent("--enable-admission-plugins=", params) { - return !hasFlagArgumentIncluded("--enable-admission-plugins=", "AlwaysAdmit", params) + if boolean.IsSingleFlagPresent("--enable-admission-plugins=", params) { + return !args.HasFlagArgumentIncluded("--enable-admission-plugins=", "AlwaysAdmit", params) } - if isSingleFlagPresent("--admission-control=", params) { - return !hasFlagArgumentIncluded("--admission-control=", "AlwaysAdmit", params) + if boolean.IsSingleFlagPresent("--admission-control=", params) { + return !args.HasFlagArgumentIncluded("--admission-control=", "AlwaysAdmit", params) } return false } // IsAlwaysPullImagesAdmissionControlPluginIncluded validates AlwaysPullImages is included in admission control plugins. func IsAlwaysPullImagesAdmissionControlPluginIncluded(params []string) bool { - if isSingleFlagPresent("--enable-admission-plugins=", params) { - return hasFlagArgumentIncluded("--enable-admission-plugins=", "AlwaysPullImages", params) + if boolean.IsSingleFlagPresent("--enable-admission-plugins=", params) { + return args.HasFlagArgumentIncluded("--enable-admission-plugins=", "AlwaysPullImages", params) } - if isSingleFlagPresent("--admission-control=", params) { - return hasFlagArgumentIncluded("--admission-control=", "AlwaysPullImages", params) + if boolean.IsSingleFlagPresent("--admission-control=", params) { + return args.HasFlagArgumentIncluded("--admission-control=", "AlwaysPullImages", params) } return false } // IsDenyEscalatingExecAdmissionControlPluginIncluded validates DenyEscalatingExec is included in admission control plugins. func IsDenyEscalatingExecAdmissionControlPluginIncluded(params []string) bool { - if isSingleFlagPresent("--enable-admission-plugins=", params) { - return hasFlagArgumentIncluded("--enable-admission-plugins=", "DenyEscalatingExec", params) + if boolean.IsSingleFlagPresent("--enable-admission-plugins=", params) { + return args.HasFlagArgumentIncluded("--enable-admission-plugins=", "DenyEscalatingExec", params) } - if isSingleFlagPresent("--admission-control=", params) { - return hasFlagArgumentIncluded("--admission-control=", "DenyEscalatingExec", params) + if boolean.IsSingleFlagPresent("--admission-control=", params) { + return args.HasFlagArgumentIncluded("--admission-control=", "DenyEscalatingExec", params) } return false } // IsSecurityContextDenyAdmissionControlPluginIncluded validates SecurityContextDeny is included in admission control plugins. func IsSecurityContextDenyAdmissionControlPluginIncluded(params []string) bool { - if isSingleFlagPresent("--enable-admission-plugins=", params) { - return hasFlagArgumentIncluded("--enable-admission-plugins=", "SecurityContextDeny", params) + if boolean.IsSingleFlagPresent("--enable-admission-plugins=", params) { + return args.HasFlagArgumentIncluded("--enable-admission-plugins=", "SecurityContextDeny", params) } - if isSingleFlagPresent("--admission-control=", params) { - return hasFlagArgumentIncluded("--admission-control=", "SecurityContextDeny", params) + if boolean.IsSingleFlagPresent("--admission-control=", params) { + return args.HasFlagArgumentIncluded("--admission-control=", "SecurityContextDeny", params) } return false } // IsPodSecurityPolicyAdmissionControlPluginIncluded validates PodSecurityPolicy is included in admission control plugins. func IsPodSecurityPolicyAdmissionControlPluginIncluded(params []string) bool { - if isSingleFlagPresent("--enable-admission-plugins=", params) { - return hasFlagArgumentIncluded("--enable-admission-plugins=", "PodSecurityPolicy", params) + if boolean.IsSingleFlagPresent("--enable-admission-plugins=", params) { + return args.HasFlagArgumentIncluded("--enable-admission-plugins=", "PodSecurityPolicy", params) } - if isSingleFlagPresent("--admission-control=", params) { - return hasFlagArgumentIncluded("--admission-control=", "PodSecurityPolicy", params) + if boolean.IsSingleFlagPresent("--admission-control=", params) { + return args.HasFlagArgumentIncluded("--admission-control=", "PodSecurityPolicy", params) } return false } // IsServiceAccountAdmissionControlPluginIncluded validates ServiceAccount is included in admission control plugins. func IsServiceAccountAdmissionControlPluginIncluded(params []string) bool { - if isSingleFlagPresent("--enable-admission-plugins=", params) { - return hasFlagArgumentIncluded("--enable-admission-plugins=", "ServiceAccount", params) + if boolean.IsSingleFlagPresent("--enable-admission-plugins=", params) { + return args.HasFlagArgumentIncluded("--enable-admission-plugins=", "ServiceAccount", params) } - if isSingleFlagPresent("--admission-control=", params) { - return hasFlagArgumentIncluded("--admission-control=", "ServiceAccount", params) + if boolean.IsSingleFlagPresent("--admission-control=", params) { + return args.HasFlagArgumentIncluded("--admission-control=", "ServiceAccount", params) } return false } // IsNodeRestrictionAdmissionControlPluginIncluded validates NodeRestriction is included in admission control plugins. func IsNodeRestrictionAdmissionControlPluginIncluded(params []string) bool { - if isSingleFlagPresent("--enable-admission-plugins=", params) { - return hasFlagArgumentIncluded("--enable-admission-plugins=", "NodeRestriction", params) + if boolean.IsSingleFlagPresent("--enable-admission-plugins=", params) { + return args.HasFlagArgumentIncluded("--enable-admission-plugins=", "NodeRestriction", params) } - if isSingleFlagPresent("--admission-control=", params) { - return hasFlagArgumentIncluded("--admission-control=", "NodeRestriction", params) + if boolean.IsSingleFlagPresent("--admission-control=", params) { + return args.HasFlagArgumentIncluded("--admission-control=", "NodeRestriction", params) } return false } // IsEventRateLimitAdmissionControlPluginIncluded validates EventRateLimit is included in admission control plugins. func IsEventRateLimitAdmissionControlPluginIncluded(params []string) bool { - if isSingleFlagPresent("--enable-admission-plugins=", params) { - return hasFlagArgumentIncluded("--enable-admission-plugins=", "EventRateLimit", params) + if boolean.IsSingleFlagPresent("--enable-admission-plugins=", params) { + return args.HasFlagArgumentIncluded("--enable-admission-plugins=", "EventRateLimit", params) } - if isSingleFlagPresent("--admission-control=", params) { - return hasFlagArgumentIncluded("--admission-control=", "EventRateLimit", params) + if boolean.IsSingleFlagPresent("--admission-control=", params) { + return args.HasFlagArgumentIncluded("--admission-control=", "EventRateLimit", params) } return false } // IsNamespaceLifecycleAdmissionControlPluginNotExcluded validates NamespaceLifecycle is excluded from admission control plugins. func IsNamespaceLifecycleAdmissionControlPluginNotExcluded(params []string) bool { - if isSingleFlagPresent("--disable-admission-plugins=", params) { - return !hasFlagArgumentIncluded("--disable-admission-plugins=", "NamespaceLifecycle", params) - } - return true -} - -// isSingleFlagPresent checks presence of selected flag and whether it was used once. -func isSingleFlagPresent(flag string, params []string) bool { - found := filterFlags(params, flag) - if len(found) != 1 { - return false + if boolean.IsSingleFlagPresent("--disable-admission-plugins=", params) { + return !args.HasFlagArgumentIncluded("--disable-admission-plugins=", "NamespaceLifecycle", params) } return true } -// hasFlagArgumentIncluded checks whether selected flag includes requested argument. -func hasFlagArgumentIncluded(flag string, argument string, params []string) bool { - found := filterFlags(params, flag) - if len(found) != 1 { - return false - } - - _, values := splitKV(found[0], "=") - for _, v := range strings.Split(values, ",") { - if v == argument { - return true - } - } - return false -} - // IsAlwaysAllowAuthorizationModeExcluded validates AlwaysAllow is excluded from authorization modes. func IsAlwaysAllowAuthorizationModeExcluded(params []string) bool { - return isSingleFlagPresent("--authorization-mode=", params) && - !hasFlagArgumentIncluded("--authorization-mode=", "AlwaysAllow", params) + return boolean.IsSingleFlagPresent("--authorization-mode=", params) && + !args.HasFlagArgumentIncluded("--authorization-mode=", "AlwaysAllow", params) } // IsNodeAuthorizationModeIncluded validates Node is included in authorization modes. func IsNodeAuthorizationModeIncluded(params []string) bool { - return hasFlagArgumentIncluded("--authorization-mode=", "Node", params) + return args.HasFlagArgumentIncluded("--authorization-mode=", "Node", params) } // IsAuditLogPathSet validates there is single "--audit-log-path" flag and has non-empty argument. func IsAuditLogPathSet(params []string) bool { - return hasSingleFlagNonemptyArgument("--audit-log-path=", params) + return args.HasSingleFlagNonemptyArgument("--audit-log-path=", params) } // IsKubeletCertificateAuthoritySet validates there is single "--kubelet-certificate-authority" flag and has non-empty argument. func IsKubeletCertificateAuthoritySet(params []string) bool { - return hasSingleFlagNonemptyArgument("--kubelet-certificate-authority", params) + return args.HasSingleFlagNonemptyArgument("--kubelet-certificate-authority", params) } // IsClientCertificateAuthoritySet validates there is single "--client-ca-file" flag and has non-empty argument. func IsClientCertificateAuthoritySet(params []string) bool { - return hasSingleFlagNonemptyArgument("--client-ca-file", params) + return args.HasSingleFlagNonemptyArgument("--client-ca-file", params) } // IsEtcdCertificateAuthoritySet validates there is single "--etcd-cafile" flag and has non-empty argument. func IsEtcdCertificateAuthoritySet(params []string) bool { - return hasSingleFlagNonemptyArgument("--etcd-cafile", params) + return args.HasSingleFlagNonemptyArgument("--etcd-cafile", params) } // IsServiceAccountKeySet validates there is single "--service-account-key-file" flag and has non-empty argument. func IsServiceAccountKeySet(params []string) bool { - return hasSingleFlagNonemptyArgument("--service-account-key-file", params) + return args.HasSingleFlagNonemptyArgument("--service-account-key-file", params) } // IsKubeletClientCertificateAndKeySet validates there are single "--kubelet-client-certificate" and "--kubelet-client-key" flags and have non-empty arguments. func IsKubeletClientCertificateAndKeySet(params []string) bool { - return hasSingleFlagNonemptyArgument("--kubelet-client-certificate", params) && - hasSingleFlagNonemptyArgument("--kubelet-client-key", params) + return args.HasSingleFlagNonemptyArgument("--kubelet-client-certificate", params) && + args.HasSingleFlagNonemptyArgument("--kubelet-client-key", params) } // IsEtcdCertificateAndKeySet validates there are single "--etcd-certfile" and "--etcd-keyfile" flags and have non-empty arguments. func IsEtcdCertificateAndKeySet(params []string) bool { - return hasSingleFlagNonemptyArgument("--etcd-certfile", params) && - hasSingleFlagNonemptyArgument("--etcd-keyfile", params) + return args.HasSingleFlagNonemptyArgument("--etcd-certfile", params) && + args.HasSingleFlagNonemptyArgument("--etcd-keyfile", params) } // IsTLSCertificateAndKeySet validates there are single "--tls-cert-file" and "--tls-private-key-file" flags and have non-empty arguments. func IsTLSCertificateAndKeySet(params []string) bool { - return hasSingleFlagNonemptyArgument("--tls-cert-file", params) && - hasSingleFlagNonemptyArgument("--tls-private-key-file", params) -} - -// hasSingleFlagNonemptyArgument checks whether selected flag was used once and has non-empty argument. -func hasSingleFlagNonemptyArgument(flag string, params []string) bool { - found := filterFlags(params, flag) - if len(found) != 1 { - return false - } - - _, value := splitKV(found[0], "=") - if value == "" { - return false - } - return true + return args.HasSingleFlagNonemptyArgument("--tls-cert-file", params) && + args.HasSingleFlagNonemptyArgument("--tls-private-key-file", params) } // IsAuditLogMaxAgeValid validates audit log age is set and it has recommended value. func IsAuditLogMaxAgeValid(params []string) bool { - return hasSingleFlagRecommendedNumericArgument("--audit-log-maxage", auditLogAge, params) + return args.HasSingleFlagRecommendedNumericArgument("--audit-log-maxage", auditLogAge, params) } // IsAuditLogMaxBackupValid validates audit log age is set and it has recommended value. func IsAuditLogMaxBackupValid(params []string) bool { - return hasSingleFlagRecommendedNumericArgument("--audit-log-maxbackup", auditLogBackups, params) + return args.HasSingleFlagRecommendedNumericArgument("--audit-log-maxbackup", auditLogBackups, params) } // IsAuditLogMaxSizeValid validates audit log age is set and it has recommended value. func IsAuditLogMaxSizeValid(params []string) bool { - return hasSingleFlagRecommendedNumericArgument("--audit-log-maxsize", auditLogSize, params) -} - -// hasSingleFlagRecommendedNumericArgument checks whether selected flag was used once and has -// an argument that is greater or equal than the recommended value for given command. -func hasSingleFlagRecommendedNumericArgument(flag string, recommendation int, params []string) bool { - found := filterFlags(params, flag) - if len(found) != 1 { - return false - } - - _, value := splitKV(found[0], "=") - arg, err := strconv.Atoi(value) // what about empty parameter? - if err != nil { - return false - } - if arg < recommendation { - return false - } - return true + return args.HasSingleFlagRecommendedNumericArgument("--audit-log-maxsize", auditLogSize, params) } // IsRequestTimeoutValid validates request timeout is set and it has recommended value. func IsRequestTimeoutValid(params []string) bool { - return isFlagAbsent("--request-timeout", params) || - hasSingleFlagValidTimeout("--request-timeout", requestTimeout, 2*requestTimeout, params) -} - -// hasSingleFlagValidTimeout checks whether selected flag has valid timeout as an argument in given command. -func hasSingleFlagValidTimeout(flag string, min int, max int, params []string) bool { - found := filterFlags(params, flag) - if len(found) != 1 { - return false - } - - _, value := splitKV(found[0], "=") - timeout, err := strconv.Atoi(value) // what about empty parameter? - if err != nil { - return false - } - if timeout < min || timeout > max { - return false - } - return true + return boolean.IsFlagAbsent("--request-timeout", params) || + args.HasSingleFlagValidTimeout("--request-timeout", requestTimeout, 2*requestTimeout, params) } diff --git a/test/security/k8s/src/check/validators/master/args/args.go b/test/security/k8s/src/check/validators/master/args/args.go new file mode 100644 index 000000000..43f2a702c --- /dev/null +++ b/test/security/k8s/src/check/validators/master/args/args.go @@ -0,0 +1,127 @@ +package args + +import ( + "strconv" + "strings" +) + +const ( + portLowest = 1 + portHighest = 65536 +) + +// HasSingleFlagArgument checks whether selected flag was used once and has requested argument. +func HasSingleFlagArgument(flag string, argument string, params []string) bool { + found := filterFlags(params, flag) + if len(found) != 1 { + return false + } + + _, value := splitKV(found[0], "=") + if value != argument { + return false + } + return true +} + +// HasFlagArgumentIncluded checks whether selected flag includes requested argument. +func HasFlagArgumentIncluded(flag string, argument string, params []string) bool { + found := filterFlags(params, flag) + if len(found) != 1 { + return false + } + + _, values := splitKV(found[0], "=") + for _, v := range strings.Split(values, ",") { + if v == argument { + return true + } + } + return false +} + +// HasSingleFlagNonemptyArgument checks whether selected flag was used once and has non-empty argument. +func HasSingleFlagNonemptyArgument(flag string, params []string) bool { + found := filterFlags(params, flag) + if len(found) != 1 { + return false + } + + _, value := splitKV(found[0], "=") + if value == "" { + return false + } + return true +} + +// HasSingleFlagValidPort checks whether selected flag has valid port as an argument in given command. +func HasSingleFlagValidPort(flag string, params []string) bool { + found := filterFlags(params, flag) + if len(found) != 1 { + return false + } + + _, value := splitKV(found[0], "=") + port, err := strconv.Atoi(value) // what about empty parameter? + if err != nil { + return false + } + if port < portLowest || port > portHighest { + return false + } + return true +} + +// HasSingleFlagValidTimeout checks whether selected flag has valid timeout as an argument in given command. +func HasSingleFlagValidTimeout(flag string, min int, max int, params []string) bool { + found := filterFlags(params, flag) + if len(found) != 1 { + return false + } + + _, value := splitKV(found[0], "=") + timeout, err := strconv.Atoi(value) // what about empty parameter? + if err != nil { + return false + } + if timeout < min || timeout > max { + return false + } + return true +} + +// HasSingleFlagRecommendedNumericArgument checks whether selected flag was used once and has +// an argument that is greater or equal than the recommended value for given command. +func HasSingleFlagRecommendedNumericArgument(flag string, recommendation int, params []string) bool { + found := filterFlags(params, flag) + if len(found) != 1 { + return false + } + + _, value := splitKV(found[0], "=") + arg, err := strconv.Atoi(value) // what about empty parameter? + if err != nil { + return false + } + if arg < recommendation { + return false + } + return true +} + +// filterFlags returns all occurrences of selected flag. +func filterFlags(strs []string, flag string) []string { + var filtered []string + for _, str := range strs { + if strings.HasPrefix(str, flag) { + filtered = append(filtered, str) + } + } + return filtered +} + +// splitKV splits key and value (after first occurrence of separator). +func splitKV(s, sep string) (string, string) { + ret := strings.SplitN(s, sep, 2) + return ret[0], ret[1] +} diff --git a/test/security/k8s/src/check/validators/master/boolean/boolean.go b/test/security/k8s/src/check/validators/master/boolean/boolean.go new file mode 100644 index 000000000..dba73c1e8 --- /dev/null +++ b/test/security/k8s/src/check/validators/master/boolean/boolean.go @@ -0,0 +1,34 @@ +package boolean + +import ( + "strings" +) + +// IsSingleFlagPresent checks presence of selected flag and whether it was used once. +func IsSingleFlagPresent(flag string, params []string) bool { + found := filterFlags(params, flag) + if len(found) != 1 { + return false + } + return true +} + +// IsFlagAbsent checks absence of selected flag in parameters. +func IsFlagAbsent(flag string, params []string) bool { + found := filterFlags(params, flag) + if len(found) != 0 { + return false + } + return true +} + +// filterFlags returns all occurrences of selected flag. +func filterFlags(strs []string, flag string) []string { + var filtered []string + for _, str := range strs { + if strings.HasPrefix(str, flag) { + filtered = append(filtered, str) + } + } + return filtered +} |