bump libseccomp-golang v0.9.1

full diff: 32f571b700...689e3c1541

Release notes:

* Version 0.9.1 - May 21, 2019
- Minimum supported version of libseccomp bumped to v2.2.0
- Use Libseccomp's `seccomp_version` API to retrieve library version
- Unconditionally set TSync attribute for filters, due to Go's heavily threaded nature
- Fix CVE-2017-18367 - Multiple syscall arguments were incorrectly combined with logical-OR, instead of logical-AND
- Fix a failure to build on Debian-based distributions due to CGo code
- Fix unit test failures on 32-bit architectures
- Improve several errors to be more verbose about their causes
- Add support for SCMP_ACT_LOG (with libseccomp versions 2.4.x and higher), permitting syscalls but logging their execution
- Add support for SCMP_FLTATR_CTL_LOG (with libseccomp versions 2.4.x and higher), logging not-allowed actions when they are denied

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor.conf

@@ -83,7 +83,7 @@ google.golang.org/grpc                              25c4f928eaa6d96443009bd84238
 github.com/opencontainers/runc                      425e105d5a03fabd737a126ad93d62a9eeede87f # v1.0.0-rc8
 github.com/opencontainers/runtime-spec              29686dbc5559d93fb1ef402eeda3e35c38d75af4 # v1.0.1-59-g29686db
 github.com/opencontainers/image-spec                d60099175f88c47cd379c4738d158884749ed235 # v1.0.1
-github.com/seccomp/libseccomp-golang                32f571b70023028bd57d9288c20efbcb237f3ce0
+github.com/seccomp/libseccomp-golang                689e3c1541a84461afc49c1c87352a6cedf72e9c # v0.9.1
 
 # libcontainer deps (see src/github.com/opencontainers/runc/Godeps/Godeps.json)
 github.com/coreos/go-systemd                        39ca1b05acc7ad1220e09f133283b8859a8b71ab # v17

vendor/github.com/seccomp/libseccomp-golang/README

@@ -24,3 +24,28 @@ please note that a Google account is not required to subscribe to the mailing
 list.
 
 	-> https://groups.google.com/d/forum/libseccomp
+
+Documentation is also available at:
+
+	-> https://godoc.org/github.com/seccomp/libseccomp-golang
+
+* Installing the package
+
+The libseccomp-golang bindings require at least Go v1.2.1 and GCC v4.8.4;
+earlier versions may yield unpredictable results.  If you meet these
+requirements you can install this package using the command below:
+
+	$ go get github.com/seccomp/libseccomp-golang
+
+* Testing the Library
+
+A number of tests and lint related recipes are provided in the Makefile, if
+you want to run the standard regression tests, you can excute the following:
+
+	$ make check
+
+In order to execute the 'make lint' recipe the 'golint' tool is needed, it
+can be found at:
+
+	-> https://github.com/golang/lint
+

vendor/github.com/seccomp/libseccomp-golang/seccomp.go

@@ -27,6 +27,28 @@ import "C"
 
 // Exported types
 
+// VersionError denotes that the system libseccomp version is incompatible
+// with this package.
+type VersionError struct {
+	message string
+	minimum string
+}
+
+func (e VersionError) Error() string {
+	format := "Libseccomp version too low: "
+	if e.message != "" {
+		format += e.message + ": "
+	}
+	format += "minimum supported is "
+	if e.minimum != "" {
+		format += e.minimum + ": "
+	} else {
+		format += "2.2.0: "
+	}
+	format += "detected %d.%d.%d"
+	return fmt.Sprintf(format, verMajor, verMinor, verMicro)
+}
+
 // ScmpArch represents a CPU architecture. Seccomp can restrict syscalls on a
 // per-architecture basis.
 type ScmpArch uint
@@ -54,8 +76,8 @@ type ScmpSyscall int32
 
 const (
 	// Valid architectures recognized by libseccomp
-	// ARM64 and all MIPS architectures are unsupported by versions of the
+	// PowerPC and S390(x) architectures are unavailable below library version
-	// library before v2.2 and will return errors if used
+	// v2.3.0 and will returns errors if used with incompatible libraries
 
 	// ArchInvalid is a placeholder to ensure uninitialized ScmpArch
 	// variables are invalid
@@ -115,6 +137,10 @@ const (
 	ActTrace ScmpAction = iota
 	// ActAllow permits the syscall to continue execution
 	ActAllow ScmpAction = iota
+	// ActLog permits the syscall to continue execution after logging it.
+	// This action is only usable when libseccomp API level 3 or higher is
+	// supported.
+	ActLog ScmpAction = iota
 )
 
 const (
@@ -151,6 +177,10 @@ const (
 // GetArchFromString returns an ScmpArch constant from a string representing an
 // architecture
 func GetArchFromString(arch string) (ScmpArch, error) {
+	if err := ensureSupportedVersion(); err != nil {
+		return ArchInvalid, err
+	}
+
 	switch strings.ToLower(arch) {
 	case "x86":
 		return ArchX86, nil
@@ -185,7 +215,7 @@ func GetArchFromString(arch string) (ScmpArch, error) {
 	case "s390x":
 		return ArchS390X, nil
 	default:
-		return ArchInvalid, fmt.Errorf("cannot convert unrecognized string %s", arch)
+		return ArchInvalid, fmt.Errorf("cannot convert unrecognized string %q", arch)
 	}
 }
 
@@ -229,7 +259,7 @@ func (a ScmpArch) String() string {
 	case ArchInvalid:
 		return "Invalid architecture"
 	default:
-		return "Unknown architecture"
+		return fmt.Sprintf("Unknown architecture %#x", uint(a))
 	}
 }
 
@@ -253,7 +283,7 @@ func (a ScmpCompareOp) String() string {
 	case CompareInvalid:
 		return "Invalid comparison operator"
 	default:
-		return "Unrecognized comparison operator"
+		return fmt.Sprintf("Unrecognized comparison operator %#x", uint(a))
 	}
 }
 
@@ -269,10 +299,12 @@ func (a ScmpAction) String() string {
 	case ActTrace:
 		return fmt.Sprintf("Action: Notify tracing processes with code %d",
 			(a >> 16))
+	case ActLog:
+		return "Action: Log system call"
 	case ActAllow:
 		return "Action: Allow system call"
 	default:
-		return "Unrecognized Action"
+		return fmt.Sprintf("Unrecognized Action %#x", uint(a))
 	}
 }
 
@@ -298,10 +330,29 @@ func (a ScmpAction) GetReturnCode() int16 {
 // GetLibraryVersion returns the version of the library the bindings are built
 // against.
 // The version is formatted as follows: Major.Minor.Micro
-func GetLibraryVersion() (major, minor, micro int) {
+func GetLibraryVersion() (major, minor, micro uint) {
 	return verMajor, verMinor, verMicro
 }
 
+// GetApi returns the API level supported by the system.
+// Returns a positive int containing the API level, or 0 with an error if the
+// API level could not be detected due to the library being older than v2.4.0.
+// See the seccomp_api_get(3) man page for details on available API levels:
+// https://github.com/seccomp/libseccomp/blob/master/doc/man/man3/seccomp_api_get.3
+func GetApi() (uint, error) {
+	return getApi()
+}
+
+// SetApi forcibly sets the API level. General use of this function is strongly
+// discouraged.
+// Returns an error if the API level could not be set. An error is always
+// returned if the library is older than v2.4.0
+// See the seccomp_api_get(3) man page for details on available API levels:
+// https://github.com/seccomp/libseccomp/blob/master/doc/man/man3/seccomp_api_get.3
+func SetApi(api uint) error {
+	return setApi(api)
+}
+
 // Syscall functions
 
 // GetName retrieves the name of a syscall from its number.
@@ -324,7 +375,7 @@ func (s ScmpSyscall) GetNameByArch(arch ScmpArch) (string, error) {
 
 	cString := C.seccomp_syscall_resolve_num_arch(arch.toNative(), C.int(s))
 	if cString == nil {
-		return "", fmt.Errorf("could not resolve syscall name")
+		return "", fmt.Errorf("could not resolve syscall name for %#x", int32(s))
 	}
 	defer C.free(unsafe.Pointer(cString))
 
@@ -338,12 +389,16 @@ func (s ScmpSyscall) GetNameByArch(arch ScmpArch) (string, error) {
 // Returns the number of the syscall, or an error if no syscall with that name
 // was found.
 func GetSyscallFromName(name string) (ScmpSyscall, error) {
+	if err := ensureSupportedVersion(); err != nil {
+		return 0, err
+	}
+
 	cString := C.CString(name)
 	defer C.free(unsafe.Pointer(cString))
 
 	result := C.seccomp_syscall_resolve_name(cString)
 	if result == scmpError {
-		return 0, fmt.Errorf("could not resolve name to syscall")
+		return 0, fmt.Errorf("could not resolve name to syscall: %q", name)
 	}
 
 	return ScmpSyscall(result), nil
@@ -355,6 +410,9 @@ func GetSyscallFromName(name string) (ScmpSyscall, error) {
 // Returns the number of the syscall, or an error if an invalid architecture is
 // passed or a syscall with that name was not found.
 func GetSyscallFromNameByArch(name string, arch ScmpArch) (ScmpSyscall, error) {
+	if err := ensureSupportedVersion(); err != nil {
+		return 0, err
+	}
 	if err := sanitizeArch(arch); err != nil {
 		return 0, err
 	}
@@ -364,7 +422,7 @@ func GetSyscallFromNameByArch(name string, arch ScmpArch) (ScmpSyscall, error) {
 
 	result := C.seccomp_syscall_resolve_name_arch(arch.toNative(), cString)
 	if result == scmpError {
-		return 0, fmt.Errorf("could not resolve name to syscall")
+		return 0, fmt.Errorf("could not resolve name to syscall: %q on %v", name, arch)
 	}
 
 	return ScmpSyscall(result), nil
@@ -386,12 +444,16 @@ func GetSyscallFromNameByArch(name string, arch ScmpArch) (ScmpSyscall, error) {
 func MakeCondition(arg uint, comparison ScmpCompareOp, values ...uint64) (ScmpCondition, error) {
 	var condStruct ScmpCondition
 
+	if err := ensureSupportedVersion(); err != nil {
+		return condStruct, err
+	}
+
 	if comparison == CompareInvalid {
 		return condStruct, fmt.Errorf("invalid comparison operator")
 	} else if arg > 5 {
-		return condStruct, fmt.Errorf("syscalls only have up to 6 arguments")
+		return condStruct, fmt.Errorf("syscalls only have up to 6 arguments (%d given)", arg)
 	} else if len(values) > 2 {
-		return condStruct, fmt.Errorf("conditions can have at most 2 arguments")
+		return condStruct, fmt.Errorf("conditions can have at most 2 arguments (%d given)", len(values))
 	} else if len(values) == 0 {
 		return condStruct, fmt.Errorf("must provide at least one value to compare against")
 	}
@@ -413,6 +475,10 @@ func MakeCondition(arg uint, comparison ScmpCompareOp, values ...uint64) (ScmpCo
 // GetNativeArch returns architecture token representing the native kernel
 // architecture
 func GetNativeArch() (ScmpArch, error) {
+	if err := ensureSupportedVersion(); err != nil {
+		return ArchInvalid, err
+	}
+
 	arch := C.seccomp_arch_native()
 
 	return archFromNative(arch)
@@ -435,6 +501,10 @@ type ScmpFilter struct {
 // Returns a reference to a valid filter context, or nil and an error if the
 // filter context could not be created or an invalid default action was given.
 func NewFilter(defaultAction ScmpAction) (*ScmpFilter, error) {
+	if err := ensureSupportedVersion(); err != nil {
+		return nil, err
+	}
+
 	if err := sanitizeAction(defaultAction); err != nil {
 		return nil, err
 	}
@@ -449,6 +519,13 @@ func NewFilter(defaultAction ScmpAction) (*ScmpFilter, error) {
 	filter.valid = true
 	runtime.SetFinalizer(filter, filterFinalizer)
 
+	// Enable TSync so all goroutines will receive the same rules
+	// If the kernel does not support TSYNC, allow us to continue without error
+	if err := filter.setFilterAttr(filterAttrTsync, 0x1); err != nil && err != syscall.ENOTSUP {
+		filter.Release()
+		return nil, fmt.Errorf("could not create filter - error setting tsync bit: %v", err)
+	}
+
 	return filter, nil
 }
 
@@ -505,7 +582,7 @@ func (f *ScmpFilter) Release() {
 // The source filter src will be released as part of the process, and will no
 // longer be usable or valid after this call.
 // To be merged, filters must NOT share any architectures, and all their
-// attributes (Default Action, Bad Arch Action, No New Privs and TSync bools)
+// attributes (Default Action, Bad Arch Action, and No New Privs bools)
 // must match.
 // The filter src will be merged into the filter this is called on.
 // The architectures of the src filter not present in the destination, and all
@@ -678,24 +755,24 @@ func (f *ScmpFilter) GetNoNewPrivsBit() (bool, error) {
 	return true, nil
 }
 
-// GetTsyncBit returns whether Thread Synchronization will be enabled on the
+// GetLogBit returns the current state the Log bit will be set to on the filter
-// filter being loaded, or an error if an issue was encountered retrieving the
+// being loaded, or an error if an issue was encountered retrieving the value.
-// value.
+// The Log bit tells the kernel that all actions taken by the filter, with the
-// Thread Sync ensures that all members of the thread group of the calling
+// exception of ActAllow, should be logged.
-// process will share the same Seccomp filter set.
+// The Log bit is only usable when libseccomp API level 3 or higher is
-// Tsync is a fairly recent addition to the Linux kernel and older kernels
+// supported.
-// lack support. If the running kernel does not support Tsync and it is
+func (f *ScmpFilter) GetLogBit() (bool, error) {
-// requested in a filter, Libseccomp will not enable TSync support and will
+	log, err := f.getFilterAttr(filterAttrLog)
-// proceed as normal.
-// This function is unavailable before v2.2 of libseccomp and will return an
-// error.
-func (f *ScmpFilter) GetTsyncBit() (bool, error) {
-	tSync, err := f.getFilterAttr(filterAttrTsync)
 	if err != nil {
+		api, apiErr := getApi()
+		if (apiErr != nil && api == 0) || (apiErr == nil && api < 3) {
+			return false, fmt.Errorf("getting the log bit is only supported in libseccomp 2.4.0 and newer with API level 3 or higher")
+		}
+
 		return false, err
 	}
 
-	if tSync == 0 {
+	if log == 0 {
 		return false, nil
 	}
 
@@ -728,25 +805,26 @@ func (f *ScmpFilter) SetNoNewPrivsBit(state bool) error {
 	return f.setFilterAttr(filterAttrNNP, toSet)
 }
 
-// SetTsync sets whether Thread Synchronization will be enabled on the filter
+// SetLogBit sets the state of the Log bit, which will be applied on filter
-// being loaded. Returns an error if setting Tsync failed, or the filter is
+// load, or an error if an issue was encountered setting the value.
-// invalid.
+// The Log bit is only usable when libseccomp API level 3 or higher is
-// Thread Sync ensures that all members of the thread group of the calling
+// supported.
-// process will share the same Seccomp filter set.
+func (f *ScmpFilter) SetLogBit(state bool) error {
-// Tsync is a fairly recent addition to the Linux kernel and older kernels
-// lack support. If the running kernel does not support Tsync and it is
-// requested in a filter, Libseccomp will not enable TSync support and will
-// proceed as normal.
-// This function is unavailable before v2.2 of libseccomp and will return an
-// error.
-func (f *ScmpFilter) SetTsync(enable bool) error {
 	var toSet C.uint32_t = 0x0
 
-	if enable {
+	if state {
 		toSet = 0x1
 	}
 
-	return f.setFilterAttr(filterAttrTsync, toSet)
+	err := f.setFilterAttr(filterAttrLog, toSet)
+	if err != nil {
+		api, apiErr := getApi()
+		if (apiErr != nil && api == 0) || (apiErr == nil && api < 3) {
+			return fmt.Errorf("setting the log bit is only supported in libseccomp 2.4.0 and newer with API level 3 or higher")
+		}
+	}
+
+	return err
 }
 
 // SetSyscallPriority sets a syscall's priority.

vendor/github.com/seccomp/libseccomp-golang/seccomp_internal.go

@@ -7,7 +7,6 @@ package seccomp
 
 import (
 	"fmt"
-	"os"
 	"syscall"
 )
 
@@ -17,47 +16,20 @@ import (
 
 // #cgo pkg-config: libseccomp
 /*
+#include <errno.h>
 #include <stdlib.h>
 #include <seccomp.h>
 
 #if SCMP_VER_MAJOR < 2
-#error Minimum supported version of Libseccomp is v2.1.0
+#error Minimum supported version of Libseccomp is v2.2.0
-#elif SCMP_VER_MAJOR == 2 && SCMP_VER_MINOR < 1
+#elif SCMP_VER_MAJOR == 2 && SCMP_VER_MINOR < 2
-#error Minimum supported version of Libseccomp is v2.1.0
+#error Minimum supported version of Libseccomp is v2.2.0
 #endif
 
 #define ARCH_BAD ~0
 
 const uint32_t C_ARCH_BAD = ARCH_BAD;
 
-#ifndef SCMP_ARCH_AARCH64
-#define SCMP_ARCH_AARCH64 ARCH_BAD
-#endif
-
-#ifndef SCMP_ARCH_MIPS
-#define SCMP_ARCH_MIPS ARCH_BAD
-#endif
-
-#ifndef SCMP_ARCH_MIPS64
-#define SCMP_ARCH_MIPS64 ARCH_BAD
-#endif
-
-#ifndef SCMP_ARCH_MIPS64N32
-#define SCMP_ARCH_MIPS64N32 ARCH_BAD
-#endif
-
-#ifndef SCMP_ARCH_MIPSEL
-#define SCMP_ARCH_MIPSEL ARCH_BAD
-#endif
-
-#ifndef SCMP_ARCH_MIPSEL64
-#define SCMP_ARCH_MIPSEL64 ARCH_BAD
-#endif
-
-#ifndef SCMP_ARCH_MIPSEL64N32
-#define SCMP_ARCH_MIPSEL64N32 ARCH_BAD
-#endif
-
 #ifndef SCMP_ARCH_PPC
 #define SCMP_ARCH_PPC ARCH_BAD
 #endif
@@ -96,22 +68,29 @@ const uint32_t C_ARCH_PPC64LE      = SCMP_ARCH_PPC64LE;
 const uint32_t C_ARCH_S390         = SCMP_ARCH_S390;
 const uint32_t C_ARCH_S390X        = SCMP_ARCH_S390X;
 
+#ifndef SCMP_ACT_LOG
+#define SCMP_ACT_LOG 0x7ffc0000U
+#endif
+
 const uint32_t C_ACT_KILL          = SCMP_ACT_KILL;
 const uint32_t C_ACT_TRAP          = SCMP_ACT_TRAP;
 const uint32_t C_ACT_ERRNO         = SCMP_ACT_ERRNO(0);
 const uint32_t C_ACT_TRACE         = SCMP_ACT_TRACE(0);
+const uint32_t C_ACT_LOG           = SCMP_ACT_LOG;
 const uint32_t C_ACT_ALLOW         = SCMP_ACT_ALLOW;
 
-// If TSync is not supported, make sure it doesn't map to a supported filter attribute
+// The libseccomp SCMP_FLTATR_CTL_LOG member of the scmp_filter_attr enum was
-// Don't worry about major version < 2, the minimum version checks should catch that case
+// added in v2.4.0
-#if SCMP_VER_MAJOR == 2 && SCMP_VER_MINOR < 2
+#if (SCMP_VER_MAJOR < 2) || \
-#define SCMP_FLTATR_CTL_TSYNC _SCMP_CMP_MIN
+    (SCMP_VER_MAJOR == 2 && SCMP_VER_MINOR < 4)
+#define SCMP_FLTATR_CTL_LOG _SCMP_FLTATR_MIN
 #endif
 
 const uint32_t C_ATTRIBUTE_DEFAULT = (uint32_t)SCMP_FLTATR_ACT_DEFAULT;
 const uint32_t C_ATTRIBUTE_BADARCH = (uint32_t)SCMP_FLTATR_ACT_BADARCH;
 const uint32_t C_ATTRIBUTE_NNP     = (uint32_t)SCMP_FLTATR_CTL_NNP;
 const uint32_t C_ATTRIBUTE_TSYNC   = (uint32_t)SCMP_FLTATR_CTL_TSYNC;
+const uint32_t C_ATTRIBUTE_LOG     = (uint32_t)SCMP_FLTATR_CTL_LOG;
 
 const int      C_CMP_NE            = (int)SCMP_CMP_NE;
 const int      C_CMP_LT            = (int)SCMP_CMP_LT;
@@ -125,25 +104,80 @@ const int      C_VERSION_MAJOR     = SCMP_VER_MAJOR;
 const int      C_VERSION_MINOR     = SCMP_VER_MINOR;
 const int      C_VERSION_MICRO     = SCMP_VER_MICRO;
 
+#if SCMP_VER_MAJOR == 2 && SCMP_VER_MINOR >= 3
+unsigned int get_major_version()
+{
+        return seccomp_version()->major;
+}
+
+unsigned int get_minor_version()
+{
+        return seccomp_version()->minor;
+}
+
+unsigned int get_micro_version()
+{
+        return seccomp_version()->micro;
+}
+#else
+unsigned int get_major_version()
+{
+        return (unsigned int)C_VERSION_MAJOR;
+}
+
+unsigned int get_minor_version()
+{
+        return (unsigned int)C_VERSION_MINOR;
+}
+
+unsigned int get_micro_version()
+{
+        return (unsigned int)C_VERSION_MICRO;
+}
+#endif
+
+// The libseccomp API level functions were added in v2.4.0
+#if (SCMP_VER_MAJOR < 2) || \
+    (SCMP_VER_MAJOR == 2 && SCMP_VER_MINOR < 4)
+const unsigned int seccomp_api_get(void)
+{
+	// libseccomp-golang requires libseccomp v2.2.0, at a minimum, which
+	// supported API level 2. However, the kernel may not support API level
+	// 2 constructs which are the seccomp() system call and the TSYNC
+	// filter flag. Return the "reserved" value of 0 here to indicate that
+	// proper API level support is not available in libseccomp.
+	return 0;
+}
+
+int seccomp_api_set(unsigned int level)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
 typedef struct scmp_arg_cmp* scmp_cast_t;
 
-// Wrapper to create an scmp_arg_cmp struct
+void* make_arg_cmp_array(unsigned int length)
-void*
-make_struct_arg_cmp(
-                    unsigned int arg,
-                    int compare,
-                    uint64_t a,
-                    uint64_t b
-                   )
 {
-	struct scmp_arg_cmp *s = malloc(sizeof(struct scmp_arg_cmp));
+        return calloc(length, sizeof(struct scmp_arg_cmp));
+}
 
-	s->arg = arg;
+// Wrapper to add an scmp_arg_cmp struct to an existing arg_cmp array
-	s->op = compare;
+void add_struct_arg_cmp(
-	s->datum_a = a;
+                        struct scmp_arg_cmp* arr,
-	s->datum_b = b;
+                        unsigned int pos,
+                        unsigned int arg,
+                        int compare,
+                        uint64_t a,
+                        uint64_t b
+                       )
+{
+        arr[pos].arg = arg;
+        arr[pos].op = compare;
+        arr[pos].datum_a = a;
+        arr[pos].datum_b = b;
 
-	return s;
+        return;
 }
 */
 import "C"
@@ -158,6 +192,7 @@ const (
 	filterAttrActBadArch scmpFilterAttr = iota
 	filterAttrNNP        scmpFilterAttr = iota
 	filterAttrTsync      scmpFilterAttr = iota
+	filterAttrLog        scmpFilterAttr = iota
 )
 
 const (
@@ -168,7 +203,7 @@ const (
 	archEnd   ScmpArch = ArchS390X
 	// Comparison boundaries to check for action validity
 	actionStart ScmpAction = ActKill
-	actionEnd   ScmpAction = ActAllow
+	actionEnd   ScmpAction = ActLog
 	// Comparison boundaries to check for comparison operator validity
 	compareOpStart ScmpCompareOp = CompareNotEqual
 	compareOpEnd   ScmpCompareOp = CompareMaskedEqual
@@ -178,26 +213,49 @@ var (
 	// Error thrown on bad filter context
 	errBadFilter = fmt.Errorf("filter is invalid or uninitialized")
 	// Constants representing library major, minor, and micro versions
-	verMajor = int(C.C_VERSION_MAJOR)
+	verMajor = uint(C.get_major_version())
-	verMinor = int(C.C_VERSION_MINOR)
+	verMinor = uint(C.get_minor_version())
-	verMicro = int(C.C_VERSION_MICRO)
+	verMicro = uint(C.get_micro_version())
 )
 
 // Nonexported functions
 
 // Check if library version is greater than or equal to the given one
-func checkVersionAbove(major, minor, micro int) bool {
+func checkVersionAbove(major, minor, micro uint) bool {
 	return (verMajor > major) ||
 		(verMajor == major && verMinor > minor) ||
 		(verMajor == major && verMinor == minor && verMicro >= micro)
 }
 
-// Init function: Verify library version is appropriate
+// Ensure that the library is supported, i.e. >= 2.2.0.
-func init() {
+func ensureSupportedVersion() error {
-	if !checkVersionAbove(2, 1, 0) {
+	if !checkVersionAbove(2, 2, 0) {
-		fmt.Fprintf(os.Stderr, "Libseccomp version too low: minimum supported is 2.1.0, detected %d.%d.%d", C.C_VERSION_MAJOR, C.C_VERSION_MINOR, C.C_VERSION_MICRO)
+		return VersionError{}
-		os.Exit(-1)
 	}
+	return nil
+}
+
+// Get the API level
+func getApi() (uint, error) {
+	api := C.seccomp_api_get()
+	if api == 0 {
+		return 0, fmt.Errorf("API level operations are not supported")
+	}
+
+	return uint(api), nil
+}
+
+// Set the API level
+func setApi(api uint) error {
+	if retCode := C.seccomp_api_set(C.uint(api)); retCode != 0 {
+		if syscall.Errno(-1*retCode) == syscall.EOPNOTSUPP {
+			return fmt.Errorf("API level operations are not supported")
+		}
+
+		return fmt.Errorf("could not set API level: %v", retCode)
+	}
+
+	return nil
 }
 
 // Filter helpers
@@ -216,10 +274,6 @@ func (f *ScmpFilter) getFilterAttr(attr scmpFilterAttr) (C.uint32_t, error) {
 		return 0x0, errBadFilter
 	}
 
-	if !checkVersionAbove(2, 2, 0) && attr == filterAttrTsync {
-		return 0x0, fmt.Errorf("the thread synchronization attribute is not supported in this version of the library")
-	}
-
 	var attribute C.uint32_t
 
 	retCode := C.seccomp_attr_get(f.filterCtx, attr.toNative(), &attribute)
@@ -239,10 +293,6 @@ func (f *ScmpFilter) setFilterAttr(attr scmpFilterAttr, value C.uint32_t) error
 		return errBadFilter
 	}
 
-	if !checkVersionAbove(2, 2, 0) && attr == filterAttrTsync {
-		return fmt.Errorf("the thread synchronization attribute is not supported in this version of the library")
-	}
-
 	retCode := C.seccomp_attr_set(f.filterCtx, attr.toNative(), value)
 	if retCode != 0 {
 		return syscall.Errno(-1 * retCode)
@@ -254,12 +304,9 @@ func (f *ScmpFilter) setFilterAttr(attr scmpFilterAttr, value C.uint32_t) error
 // DOES NOT LOCK OR CHECK VALIDITY
 // Assumes caller has already done this
 // Wrapper for seccomp_rule_add_... functions
-func (f *ScmpFilter) addRuleWrapper(call ScmpSyscall, action ScmpAction, exact bool, cond C.scmp_cast_t) error {
+func (f *ScmpFilter) addRuleWrapper(call ScmpSyscall, action ScmpAction, exact bool, length C.uint, cond C.scmp_cast_t) error {
-	var length C.uint
+	if length != 0 && cond == nil {
-	if cond != nil {
+		return fmt.Errorf("null conditions list, but length is nonzero")
-		length = 1
-	} else {
-		length = 0
 	}
 
 	var retCode C.int
@@ -270,9 +317,11 @@ func (f *ScmpFilter) addRuleWrapper(call ScmpSyscall, action ScmpAction, exact b
 	}
 
 	if syscall.Errno(-1*retCode) == syscall.EFAULT {
-		return fmt.Errorf("unrecognized syscall")
+		return fmt.Errorf("unrecognized syscall %#x", int32(call))
 	} else if syscall.Errno(-1*retCode) == syscall.EPERM {
 		return fmt.Errorf("requested action matches default action of filter")
+	} else if syscall.Errno(-1*retCode) == syscall.EINVAL {
+		return fmt.Errorf("two checks on same syscall argument")
 	} else if retCode != 0 {
 		return syscall.Errno(-1 * retCode)
 	}
@@ -290,22 +339,32 @@ func (f *ScmpFilter) addRuleGeneric(call ScmpSyscall, action ScmpAction, exact b
 	}
 
 	if len(conds) == 0 {
-		if err := f.addRuleWrapper(call, action, exact, nil); err != nil {
+		if err := f.addRuleWrapper(call, action, exact, 0, nil); err != nil {
 			return err
 		}
 	} else {
 		// We don't support conditional filtering in library version v2.1
 		if !checkVersionAbove(2, 2, 1) {
-			return fmt.Errorf("conditional filtering requires libseccomp version >= 2.2.1")
+			return VersionError{
+				message: "conditional filtering is not supported",
+				minimum: "2.2.1",
+			}
 		}
 
-		for _, cond := range conds {
+		argsArr := C.make_arg_cmp_array(C.uint(len(conds)))
-			cmpStruct := C.make_struct_arg_cmp(C.uint(cond.Argument), cond.Op.toNative(), C.uint64_t(cond.Operand1), C.uint64_t(cond.Operand2))
+		if argsArr == nil {
-			defer C.free(cmpStruct)
+			return fmt.Errorf("error allocating memory for conditions")
+		}
+		defer C.free(argsArr)
 
-			if err := f.addRuleWrapper(call, action, exact, C.scmp_cast_t(cmpStruct)); err != nil {
+		for i, cond := range conds {
-				return err
+			C.add_struct_arg_cmp(C.scmp_cast_t(argsArr), C.uint(i),
-			}
+				C.uint(cond.Argument), cond.Op.toNative(),
+				C.uint64_t(cond.Operand1), C.uint64_t(cond.Operand2))
+		}
+
+		if err := f.addRuleWrapper(call, action, exact, C.uint(len(conds)), C.scmp_cast_t(argsArr)); err != nil {
+			return err
 		}
 	}
 
@@ -317,11 +376,11 @@ func (f *ScmpFilter) addRuleGeneric(call ScmpSyscall, action ScmpAction, exact b
 // Helper - Sanitize Arch token input
 func sanitizeArch(in ScmpArch) error {
 	if in < archStart || in > archEnd {
-		return fmt.Errorf("unrecognized architecture")
+		return fmt.Errorf("unrecognized architecture %#x", uint(in))
 	}
 
 	if in.toNative() == C.C_ARCH_BAD {
-		return fmt.Errorf("architecture is not supported on this version of the library")
+		return fmt.Errorf("architecture %v is not supported on this version of the library", in)
 	}
 
 	return nil
@@ -330,7 +389,7 @@ func sanitizeArch(in ScmpArch) error {
 func sanitizeAction(in ScmpAction) error {
 	inTmp := in & 0x0000FFFF
 	if inTmp < actionStart || inTmp > actionEnd {
-		return fmt.Errorf("unrecognized action")
+		return fmt.Errorf("unrecognized action %#x", uint(inTmp))
 	}
 
 	if inTmp != ActTrace && inTmp != ActErrno && (in&0xFFFF0000) != 0 {
@@ -342,7 +401,7 @@ func sanitizeAction(in ScmpAction) error {
 
 func sanitizeCompareOp(in ScmpCompareOp) error {
 	if in < compareOpStart || in > compareOpEnd {
-		return fmt.Errorf("unrecognized comparison operator")
+		return fmt.Errorf("unrecognized comparison operator %#x", uint(in))
 	}
 
 	return nil
@@ -385,7 +444,7 @@ func archFromNative(a C.uint32_t) (ScmpArch, error) {
 	case C.C_ARCH_S390X:
 		return ArchS390X, nil
 	default:
-		return 0x0, fmt.Errorf("unrecognized architecture")
+		return 0x0, fmt.Errorf("unrecognized architecture %#x", uint32(a))
 	}
 }
 
@@ -464,10 +523,12 @@ func actionFromNative(a C.uint32_t) (ScmpAction, error) {
 		return ActErrno.SetReturnCode(int16(aTmp)), nil
 	case C.C_ACT_TRACE:
 		return ActTrace.SetReturnCode(int16(aTmp)), nil
+	case C.C_ACT_LOG:
+		return ActLog, nil
 	case C.C_ACT_ALLOW:
 		return ActAllow, nil
 	default:
-		return 0x0, fmt.Errorf("unrecognized action")
+		return 0x0, fmt.Errorf("unrecognized action %#x", uint32(a))
 	}
 }
 
@@ -482,6 +543,8 @@ func (a ScmpAction) toNative() C.uint32_t {
 		return C.C_ACT_ERRNO | (C.uint32_t(a) >> 16)
 	case ActTrace:
 		return C.C_ACT_TRACE | (C.uint32_t(a) >> 16)
+	case ActLog:
+		return C.C_ACT_LOG
 	case ActAllow:
 		return C.C_ACT_ALLOW
 	default:
@@ -500,6 +563,8 @@ func (a scmpFilterAttr) toNative() uint32 {
 		return uint32(C.C_ATTRIBUTE_NNP)
 	case filterAttrTsync:
 		return uint32(C.C_ATTRIBUTE_TSYNC)
+	case filterAttrLog:
+		return uint32(C.C_ATTRIBUTE_LOG)
 	default:
 		return 0x0
 	}