cgroup2: use cgroup_mem_swap_max and cgroup_mem_memsw_max

README.md

@@ -474,6 +474,8 @@ Options:
 	Maximum number of bytes to use in the group (default: '0' - disabled)
  --cgroup_mem_memsw_max VALUE
 	Maximum number of memory+Swap bytes to use in the group (default: '0' - disabled)
+ --cgroup_mem_swap_max VALUE
+	Maximum number of swap bytes to use in the group (default: '-1' - disabled)
  --cgroup_mem_mount VALUE
 	Location of memory cgroup FS (default: '/sys/fs/cgroup/memory')
  --cgroup_mem_parent VALUE

cgroup.cc

@@ -65,7 +65,12 @@ static bool addPidToTaskList(const std::string& cgroup_path, pid_t pid) {
 }
 
 static bool initNsFromParentMem(nsjconf_t* nsjconf, pid_t pid) {
-	if (nsjconf->cgroup_mem_max == (size_t)0 && nsjconf->cgroup_mem_memsw_max == (size_t)0) {
+	size_t memsw_max = nsjconf->cgroup_mem_memsw_max;
+	if (nsjconf->cgroup_mem_swap_max >= (ssize_t)0) {
+		memsw_max = nsjconf->cgroup_mem_swap_max + nsjconf->cgroup_mem_max;
+	}
+
+	if (nsjconf->cgroup_mem_max == (size_t)0 && memsw_max == (size_t)0) {
 		return true;
 	}
 
@@ -85,8 +90,8 @@ static bool initNsFromParentMem(nsjconf_t* nsjconf, pid_t pid) {
 		    mem_max_str, "memory cgroup max limit"));
 	}
 
-	if (nsjconf->cgroup_mem_memsw_max > (size_t)0) {
-		std::string mem_memsw_max_str = std::to_string(nsjconf->cgroup_mem_memsw_max);
+	if (memsw_max > (size_t)0) {
+		std::string mem_memsw_max_str = std::to_string(memsw_max);
 		RETURN_ON_FAILURE(writeToCgroup(mem_cgroup_path + "/memory.memsw.limit_in_bytes",
 		    mem_memsw_max_str, "memory+Swap cgroup max limit"));
 	}

cgroup2.cc

@@ -84,7 +84,12 @@ static void removeCgroup(const std::string &cgroup_path) {
 }
 
 static bool initNsFromParentMem(nsjconf_t *nsjconf, pid_t pid) {
-	if (nsjconf->cgroup_mem_max == (size_t)0 && nsjconf->cgroup_mem_memsw_max == (size_t)0) {
+	ssize_t swap_max = nsjconf->cgroup_mem_swap_max;
+	if (nsjconf->cgroup_mem_memsw_max > (size_t)0) {
+		swap_max = nsjconf->cgroup_mem_memsw_max - nsjconf->cgroup_mem_max;
+	}
+
+	if (nsjconf->cgroup_mem_max == (size_t)0 && swap_max < (ssize_t)0) {
 		return true;
 	}
 
@@ -97,9 +102,9 @@ static bool initNsFromParentMem(nsjconf_t *nsjconf, pid_t pid) {
 		    cgroup_path, "memory.max", std::to_string(nsjconf->cgroup_mem_max)));
 	}
 
-	if (nsjconf->cgroup_mem_memsw_max >= nsjconf->cgroup_mem_max) {
-		RETURN_ON_FAILURE(writeToCgroup(cgroup_path, "memory.swap.max",
-		    std::to_string(nsjconf->cgroup_mem_memsw_max - nsjconf->cgroup_mem_max)));
+	if (swap_max >= (ssize_t)0) {
+		RETURN_ON_FAILURE(
+		    writeToCgroup(cgroup_path, "memory.swap.max", std::to_string(swap_max)));
 	}
 
 	return true;

cmdline.cc

@@ -143,7 +143,8 @@ struct custom_option custom_opts[] = {
     { { "seccomp_log", no_argument, NULL, 0x0902 }, "Use SECCOMP_FILTER_FLAG_LOG. Log all actions except SECCOMP_RET_ALLOW). Supported since kernel version 4.14" },
     { { "nice_level", required_argument, NULL, 0x0903 }, "Set jailed process niceness (-20 is highest -priority, 19 is lowest). By default, set to 19" },
     { { "cgroup_mem_max", required_argument, NULL, 0x0801 }, "Maximum number of bytes to use in the group (default: '0' - disabled)" },
-    { { "cgroup_mem_memsw_max", required_argument, NULL, 0x0804 }, "Maximum number of memory+Swap bytes to use in the group (default: '0' - disabled)" },
+    { { "cgroup_mem_memsw_max", required_argument, NULL, 0x0804 }, "Maximum number of memory+swap bytes to use (default: '0' - disabled)" },
+    { { "cgroup_mem_swap_max", required_argument, NULL, 0x0805 }, "Maximum number of swap bytes to use (default: '-1' - disabled)" },
     { { "cgroup_mem_mount", required_argument, NULL, 0x0802 }, "Location of memory cgroup FS (default: '/sys/fs/cgroup/memory')" },
     { { "cgroup_mem_parent", required_argument, NULL, 0x0803 }, "Which pre-existing memory cgroup to use as a parent (default: 'NSJAIL')" },
     { { "cgroup_pids_max", required_argument, NULL, 0x0811 }, "Maximum number of pids in a cgroup (default: '0' - disabled)" },
@@ -459,6 +460,7 @@ std::unique_ptr<nsjconf_t> parseArgs(int argc, char* argv[]) {
 	nsjconf->cgroup_mem_parent = "NSJAIL";
 	nsjconf->cgroup_mem_max = (size_t)0;
 	nsjconf->cgroup_mem_memsw_max = (size_t)0;
+	nsjconf->cgroup_mem_swap_max = (ssize_t)-1;
 	nsjconf->cgroup_pids_mount = "/sys/fs/cgroup/pids";
 	nsjconf->cgroup_pids_parent = "NSJAIL";
 	nsjconf->cgroup_pids_max = 0U;
@@ -866,6 +868,9 @@ std::unique_ptr<nsjconf_t> parseArgs(int argc, char* argv[]) {
 		case 0x804:
 			nsjconf->cgroup_mem_memsw_max = (size_t)strtoull(optarg, NULL, 0);
 			break;
+		case 0x805:
+			nsjconf->cgroup_mem_swap_max = (ssize_t)strtoll(optarg, NULL, 0);
+			break;
 		case 0x811:
 			nsjconf->cgroup_pids_max = (unsigned int)strtoul(optarg, NULL, 0);
 			break;
@@ -929,6 +934,11 @@ std::unique_ptr<nsjconf_t> parseArgs(int argc, char* argv[]) {
 	}
 	setupUsers(nsjconf.get());
 
+	if (nsjconf->cgroup_mem_memsw_max > (size_t)0 &&
+	    nsjconf->cgroup_mem_swap_max >= (ssize_t)0) {
+		LOG_F("cannot set both cgroup_mem_memsw_max and cgroup_mem_swap_max");
+	}
+
 	return nsjconf;
 }
 

config.cc

@@ -252,6 +252,7 @@ static bool configParseInternal(nsjconf_t* nsjconf, const nsjail::NsJailConfig&
 
 	nsjconf->cgroup_mem_max = njc.cgroup_mem_max();
 	nsjconf->cgroup_mem_memsw_max = njc.cgroup_mem_memsw_max();
+	nsjconf->cgroup_mem_swap_max = njc.cgroup_mem_swap_max();
 	nsjconf->cgroup_mem_mount = njc.cgroup_mem_mount();
 	nsjconf->cgroup_mem_parent = njc.cgroup_mem_parent();
 	nsjconf->cgroup_pids_max = njc.cgroup_pids_max();

config.proto

@@ -213,6 +213,8 @@ message NsJailConfig {
     optional uint64 cgroup_mem_max = 67 [default = 0]; /* In bytes */
     /* If > 0, maximum cumulative size of RAM + swap used inside any jail */
     optional uint64 cgroup_mem_memsw_max = 91 [default = 0]; /* In bytes */
+    /* If >= 0, maximum cumulative size of swap used inside any jail */
+    optional int64 cgroup_mem_swap_max = 92 [default = -1]; /* In bytes */
     /* Mount point for cgroups-memory in your system */
     optional string cgroup_mem_mount = 68 [default = "/sys/fs/cgroup/memory"];
     /* Writeable directory (for the nsjail user) under cgroup_mem_mount */

nsjail.1

@@ -223,6 +223,9 @@ Maximum number of bytes to use in the group (default: '0' \- disabled)
 \fB\-\-cgroup_mem_memsw_max\fR VALUE
 Maximum number of memory+Swap bytes to use in the group (default: '0' \- disabled)
 .TP
+\fB\-\-cgroup_mem_swap_max\fR VALUE
+Maximum number of swap bytes to use in the group (default: '-1' \- disabled)
+.TP
 \fB\-\-cgroup_mem_mount\fR VALUE
 Location of memory cgroup FS (default: '/sys/fs/cgroup/memory')
 .TP

nsjail.h

@@ -149,6 +149,7 @@ struct nsjconf_t {
 	std::string cgroup_mem_parent;
 	size_t cgroup_mem_max;
 	size_t cgroup_mem_memsw_max;
+	ssize_t cgroup_mem_swap_max;
 	std::string cgroup_pids_mount;
 	std::string cgroup_pids_parent;
 	unsigned int cgroup_pids_max;