Fix the conversion of sysctl variable dots and slashes

Signed-off-by: Mengjiao Liu <mengjiao.liu@daocloud.io>

libcontainer/configs/validate/validator.go

@@ -128,6 +128,36 @@ func (v *ConfigValidator) cgroupnamespace(config *configs.Config) error {
 	return nil
 }
 
+// convertSysctlVariableToDotsSeparator can return sysctl variables in dots separator format.
+// The '/' separator is also accepted in place of a '.'.
+// Convert the sysctl variables to dots separator format for validation.
+// More info:
+//   https://man7.org/linux/man-pages/man8/sysctl.8.html
+//   https://man7.org/linux/man-pages/man5/sysctl.d.5.html
+// For example:
+// Input sysctl variable "net/ipv4/conf/eno2.100.rp_filter"
+// will return the converted value "net.ipv4.conf.eno2/100.rp_filter"
+func convertSysctlVariableToDotsSeparator(val string) string {
+	if val == "" {
+		return val
+	}
+	firstSepIndex := strings.IndexAny(val, "./")
+	if firstSepIndex == -1 || val[firstSepIndex] == '.' {
+		return val
+	}
+
+	f := func(r rune) rune {
+		switch r {
+		case '.':
+			return '/'
+		case '/':
+			return '.'
+		}
+		return r
+	}
+	return strings.Map(f, val)
+}
+
 // sysctl validates that the specified sysctl keys are valid or not.
 // /proc/sys isn't completely namespaced and depending on which namespaces
 // are specified, a subset of sysctls are permitted.
@@ -150,7 +180,7 @@ func (v *ConfigValidator) sysctl(config *configs.Config) error {
 	)
 
 	for s := range config.Sysctl {
-		s := strings.Replace(s, "/", ".", -1)
+		s := convertSysctlVariableToDotsSeparator(s)
 		if validSysctlMap[s] || strings.HasPrefix(s, "fs.mqueue.") {
 			if config.Namespaces.Contains(configs.NEWIPC) {
 				continue

libcontainer/configs/validate/validator_test.go

@@ -184,14 +184,40 @@ func TestValidateUsernamespaceWithoutUserNS(t *testing.T) {
 	}
 }
 
+// TestConvertSysctlVariableToDotsSeparator tests whether the sysctl variable
+// can be correctly converted to a dot as a separator.
+func TestConvertSysctlVariableToDotsSeparator(t *testing.T) {
+	type testCase struct {
+		in  string
+		out string
+	}
+	valid := []testCase{
+		{in: "kernel.shm_rmid_forced", out: "kernel.shm_rmid_forced"},
+		{in: "kernel/shm_rmid_forced", out: "kernel.shm_rmid_forced"},
+		{in: "net.ipv4.conf.eno2/100.rp_filter", out: "net.ipv4.conf.eno2/100.rp_filter"},
+		{in: "net/ipv4/conf/eno2.100/rp_filter", out: "net.ipv4.conf.eno2/100.rp_filter"},
+		{in: "net/ipv4/ip_local_port_range", out: "net.ipv4.ip_local_port_range"},
+		{in: "kernel/msgmax", out: "kernel.msgmax"},
+		{in: "kernel/sem", out: "kernel.sem"},
+	}
+
+	for _, test := range valid {
+		convertSysctlVal := convertSysctlVariableToDotsSeparator(test.in)
+		if convertSysctlVal != test.out {
+			t.Errorf("The sysctl variable was not converted correctly. got: %s, want: %s", convertSysctlVal, test.out)
+		}
+	}
+}
+
 func TestValidateSysctl(t *testing.T) {
 	sysctl := map[string]string{
-		"fs.mqueue.ctl": "ctl",
-		"fs/mqueue/ctl": "ctl",
-		"net.ctl":       "ctl",
-		"net/ctl":       "ctl",
-		"kernel.ctl":    "ctl",
-		"kernel/ctl":    "ctl",
+		"fs.mqueue.ctl":                    "ctl",
+		"fs/mqueue/ctl":                    "ctl",
+		"net.ctl":                          "ctl",
+		"net/ctl":                          "ctl",
+		"net.ipv4.conf.eno2/100.rp_filter": "ctl",
+		"kernel.ctl":                       "ctl",
+		"kernel/ctl":                       "ctl",
 	}
 
 	for k, v := range sysctl {
@@ -210,12 +236,13 @@ func TestValidateSysctl(t *testing.T) {
 
 func TestValidateValidSysctl(t *testing.T) {
 	sysctl := map[string]string{
-		"fs.mqueue.ctl": "ctl",
-		"fs/mqueue/ctl": "ctl",
-		"net.ctl":       "ctl",
-		"net/ctl":       "ctl",
-		"kernel.msgmax": "ctl",
-		"kernel/msgmax": "ctl",
+		"fs.mqueue.ctl":                    "ctl",
+		"fs/mqueue/ctl":                    "ctl",
+		"net.ctl":                          "ctl",
+		"net/ctl":                          "ctl",
+		"net.ipv4.conf.eno2/100.rp_filter": "ctl",
+		"kernel.msgmax":                    "ctl",
+		"kernel/msgmax":                    "ctl",
 	}
 
 	for k, v := range sysctl {