cgclassify: A command line tool to classify/re-classify already running task

From: Vivek Goyal <vgoyal@redhat.com>

o cgclassify, a command line tool to put a list of pids to the right cgroup
  based on rules in /etc/cgrules.conf. It can be mainly used for
  reclassification of tasks which are already running. Can think of two
  use cases.
        - During initial bootup, after cgroups are mounted, one needs to
          move tasks (started beofore cgroups were mounted) into right
          cgroup.

        - Once can choose to reclassify the tasks if admin has changed the
          rules and thinks a group of tasks should reclassified based on
          new rules.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>



git-svn-id: https://libcg.svn.sourceforge.net/svnroot/libcg/trunk@138 4f4bb910-9a46-0410-90c8-c897d4f1cd53

1 files changed, 148 insertions, 0 deletions

diff --git a/cgclassify.c b/cgclassify.c
new file mode 100644
index 0000000..556ed3f
--- /dev/null
+++ b/cgclassify.c
@@ -0,0 +1,148 @@
+/*
+ * Copyright RedHat Inc. 2008
+ *
+ * Authors:	Vivek Goyal <vgoyal@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <libcgroup.h>
+#include <limits.h>
+#include <pwd.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#define TEMP_BUF	81
+
+/*
+ * Go through /proc/<pid>/status file to determine the euid of the
+ * process.
+ * It returns 0 on success and negative values on failure.
+ */
+
+int euid_of_pid(pid_t pid)
+{
+	FILE *fp;
+	char path[FILENAME_MAX];
+	char buf[TEMP_BUF];
+	uid_t ruid, euid, suid, fsuid;
+
+	sprintf(path, "/proc/%d/status", pid);
+	fp = fopen(path, "r");
+	if (!fp) {
+		fprintf(stderr, "Error in opening file %s:%s\n", path,
+				strerror(errno));
+		return -1;
+	}
+
+	while (fgets(buf, TEMP_BUF, fp)) {
+		if (!strncmp(buf, "Uid:", 4)) {
+			sscanf((buf + 5), "%d%d%d%d", (int *)&ruid,
+				(int *)&euid, (int *)&suid, (int *)&fsuid);
+			dbg("Scanned proc values are %d %d %d %d\n",
+				ruid, euid, suid, fsuid);
+			return euid;
+		}
+	}
+
+	/* If we are here, we could not find euid. Return error. */
+	return -1;
+}
+
+/*
+ * Go through /proc/<pid>/status file to determine the egid of the
+ * process.
+ * It returns 0 on success and negative values on failure.
+ */
+
+int egid_of_pid(pid_t pid)
+{
+	FILE *fp;
+	char path[FILENAME_MAX];
+	char buf[TEMP_BUF];
+	gid_t rgid, egid, sgid, fsgid;
+
+	sprintf(path, "/proc/%d/status", pid);
+	fp = fopen(path, "r");
+	if (!fp) {
+		fprintf(stderr, "Error in opening file %s:%s\n", path,
+				strerror(errno));
+		return -1;
+	}
+
+	while (fgets(buf, TEMP_BUF, fp)) {
+		if (!strncmp(buf, "Gid:", 4)) {
+			sscanf((buf + 5), "%d%d%d%d", (int *)&rgid,
+				(int *)&egid, (int *)&sgid, (int *)&fsgid);
+			dbg("Scanned proc values are %d %d %d %d\n",
+				rgid, egid, sgid, fsgid);
+			return egid;
+		}
+	}
+
+	/* If we are here, we could not find egid. Return error. */
+	return -1;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret = 0, i;
+	uid_t euid;
+	gid_t egid;
+	pid_t pid;
+
+	if (argc < 2) {
+		fprintf(stderr, "usage is %s <list of pids>  \n",
+			argv[0]);
+		exit(2);
+	}
+
+
+	/* Initialize libcg */
+	ret = cgroup_init();
+	if (ret) {
+		fprintf(stderr, "libcgroup initialization failed:%d\n", ret);
+		return ret;
+	}
+
+	/* Put pids into right cgroups as per rules in /etc/cgrules.conf */
+	for (i = 1; i < argc; i++) {
+		pid = (uid_t) atoi(argv[i]);
+		euid = euid_of_pid(pid);
+		if (euid == -1) {
+			fprintf(stderr, "Error in determining euid of"
+					" pid %d\n", pid);
+			return -1;
+		}
+
+		egid = egid_of_pid(pid);
+		if (egid == -1) {
+			fprintf(stderr, "Error in determining egid of"
+					" pid %d\n", pid);
+			return -1;
+		}
+
+		/* Change the cgroup by determining the rules based on uid */
+		ret = cgroup_change_cgroup_uid_gid(euid, egid, pid);
+		if (ret) {
+			fprintf(stderr, "Error: change of cgroup failed for"
+					" pid %d\n", pid);
+			return ret;
+		}
+	}
+	return 0;
+}