Add support for a new login capability, cpumask which allows login

sessions to be pinned to cpus by login class.

lib/libutil/login.conf.5

@@ -203,6 +203,15 @@ The maximum and current limits may be specified individually by appending a
 .It Sy "Name	Type	Notes	Description
 .It "charset	string		Set $MM_CHARSET environment variable to the specified
 value.
+.It "cpumask	string		List of cpus to bind the user to.
+The syntax is the same as for the
+.Fl l
+argument of
+.Xr cpuset 1 or the word
+.Ql default .
+If set to
+.Ql default
+no action is taken.
 .It "hushlogin	bool	false	Same as having a ~/.hushlogin file.
 .It "ignorenologin	bool	false	Login not prevented by nologin.
 .It "ftp-chroot	bool	false	Limit FTP access with

lib/libutil/login_cap.h

@@ -48,7 +48,8 @@
 #define LOGIN_SETUSER		0x0040		/* set user (via setuid) */
 #define LOGIN_SETENV		0x0080		/* set user environment */
 #define LOGIN_SETMAC		0x0100		/* set user default MAC label */
-#define LOGIN_SETALL		0x01ff		/* set everything */
+#define LOGIN_SETCPUMASK	0x0200		/* set user cpumask */
+#define LOGIN_SETALL		0x03ff		/* set everything */
 
 #define BI_AUTH		"authorize"		/* accepted authentication */
 #define BI_REJECT	"reject"		/* rejected authentication */

lib/libutil/login_class.3

@@ -155,6 +155,18 @@ capability "setenv=var1 val1,var2 val2..,varN valN".
 Set the MAC label for the current process to the label specified
 in system login class database.
 .Pp
+.It LOGIN_SETCPUMASK
+Create a new
+.Xr cpuset 2
+and set the cpu affinity to the specified mask.
+The string may contain a comma separated list of numbers and/or number
+ranges as handled by the
+.Xr cpuset 1
+utility or the case-insensitive string 
+.Ql default .
+If the string is
+.Ql default
+no action will be taken.
 .It LOGIN_SETALL
 Enables all of the above settings.
 .El
@@ -186,6 +198,8 @@ or resources, a message is reported to
 .Xr syslog 3 ,
 with LOG_ERR priority and directed to the currently active facility.
 .Sh SEE ALSO
+.Xr cpuset 1 ,
+.Xr cpuset 2 ,
 .Xr setgid 2 ,
 .Xr setlogin 2 ,
 .Xr setuid 2 ,

lib/libutil/login_class.c

@@ -26,9 +26,11 @@
 __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
+#include <sys/param.h>
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/resource.h>
+#include <sys/cpuset.h>
 #include <sys/mac.h>
 #include <sys/rtprio.h>
 #include <errno.h>
@@ -239,6 +241,108 @@ setclassenvironment(login_cap_t *lc, const struct passwd * pwd, int paths)
 }
 
 
+static int
+list2cpuset(const char *list, cpuset_t *mask)
+{
+	enum { NONE, NUM, DASH } state;
+	int lastnum;
+	int curnum;
+	const char *l;
+
+	state = NONE;
+	curnum = lastnum = 0;
+	for (l = list; *l != '\0';) {
+		if (isdigit(*l)) {
+			curnum = atoi(l);
+			if (curnum > CPU_SETSIZE)
+				errx(EXIT_FAILURE,
+				    "Only %d cpus supported", CPU_SETSIZE);
+			while (isdigit(*l))
+				l++;
+			switch (state) {
+			case NONE:
+				lastnum = curnum;
+				state = NUM;
+				break;
+			case DASH:
+				for (; lastnum <= curnum; lastnum++)
+					CPU_SET(lastnum, mask);
+				state = NONE;
+				break;
+			case NUM:
+			default:
+				return (0);
+			}
+			continue;
+		}
+		switch (*l) {
+		case ',':
+			switch (state) {
+			case NONE:
+				break;
+			case NUM:
+				CPU_SET(curnum, mask);
+				state = NONE;
+				break;
+			case DASH:
+				return (0);
+				break;
+			}
+			break;
+		case '-':
+			if (state != NUM)
+				return (0);
+			state = DASH;
+			break;
+		default:
+			return (0);
+		}
+		l++;
+	}
+	switch (state) {
+		case NONE:
+			break;
+		case NUM:
+			CPU_SET(curnum, mask);
+			break;
+		case DASH:
+			return (0);
+	}
+	return 1;
+}
+
+
+void
+setclasscpumask(login_cap_t *lc)
+{
+	const char *maskstr;
+	cpuset_t maskset;
+	cpusetid_t setid;
+
+	maskstr = login_getcapstr(lc, "cpumask", NULL, NULL);
+	CPU_ZERO(&maskset);
+	if (maskstr == NULL)
+		return;
+	if (strcasecmp("default", maskstr) == 0)
+		return;
+	if (!list2cpuset(maskstr, &maskset)) {
+		syslog(LOG_WARNING,
+		    "list2cpuset(%s) invalid mask specification", maskstr);
+		return;
+	}
+
+	if (cpuset(&setid) != 0) {
+		syslog(LOG_ERR, "cpuset(): %s", strerror(errno));
+		return;
+	}
+
+	if (cpuset_setaffinity(CPU_LEVEL_CPUSET, CPU_WHICH_PID, -1,
+	    sizeof(maskset), &maskset) != 0)
+		syslog(LOG_ERR, "cpuset_setaffinity(%s): %s", maskstr,
+		    strerror(errno));
+}
+
+
 /*
  * setclasscontext()
  *
@@ -289,6 +393,9 @@ setlogincontext(login_cap_t *lc, const struct passwd *pwd,
 	/* Set environment */
 	if (flags & LOGIN_SETENV)
 	    setclassenvironment(lc, pwd, 0);
+	/* Set cpu affinity */
+	if (flags & LOGIN_SETCPUMASK)
+	    setclasscpumask(lc);
     }
     return mymask;
 }