[PATCH 2.6.13-rc1 10/11] mm: manual page migration-rc4 -- sys_migrate_pages-permissions-check-rc4.patch

[Ray Bryant <raybry@sgi.com>]

Add permissions checking to migrate_pages() system call.
The basic idea is that if you could send an arbitary
signal to a process then you are allowed to migrate
that process, or if the calling process has capability
CAP_SYS_ADMIN.  The permissions check is based
on that in check_kill_permission() in kernel/signal.c.

Signed-off-by: Ray Bryant <raybry@sgi.com>

 include/linux/capability.h |    2 ++
 mm/mmigrate.c              |   12 ++++++++++++
 2 files changed, 14 insertions(+)

Index: linux-2.6.12-rc5-mhp1-page-migration-export/include/linux/capability.h
===================================================================
--- linux-2.6.12-rc5-mhp1-page-migration-export.orig/include/linux/capability.h	2005-06-24 11:02:20.000000000 -0700
+++ linux-2.6.12-rc5-mhp1-page-migration-export/include/linux/capability.h	2005-06-24 11:02:30.000000000 -0700
@@ -233,6 +233,8 @@ typedef __u32 kernel_cap_t;
 /* Allow enabling/disabling tagged queuing on SCSI controllers and sending
    arbitrary SCSI commands */
 /* Allow setting encryption key on loopback filesystem */
+/* Allow using the migrate_pages() system call to migrate a process's pages
+   from one set of NUMA nodes to another */
 
 #define CAP_SYS_ADMIN        21
 
Index: linux-2.6.12-rc5-mhp1-page-migration-export/mm/mmigrate.c
===================================================================
--- linux-2.6.12-rc5-mhp1-page-migration-export.orig/mm/mmigrate.c	2005-06-24 11:02:20.000000000 -0700
+++ linux-2.6.12-rc5-mhp1-page-migration-export/mm/mmigrate.c	2005-06-24 11:02:30.000000000 -0700
@@ -15,6 +15,8 @@
 #include <linux/module.h>
 #include <linux/swap.h>
 #include <linux/pagemap.h>
+#include <linux/sched.h>
+#include <linux/capability.h>
 #include <linux/init.h>
 #include <linux/highmem.h>
 #include <linux/writeback.h>
@@ -734,6 +736,16 @@ sys_migrate_pages(pid_t pid, __u32 count
 	task = find_task_by_pid(pid);
 	if (task) {
 		task_lock(task);
+		/* does this task have permission to migrate that task?
+		 * (ala check_kill_permission() ) */
+	        if ((current->euid ^ task->suid) && (current->euid ^ task->uid)
+	           && (current->uid ^ task->suid) && (current->uid ^ task->uid)
+	           && !capable(CAP_SYS_ADMIN)) {
+		   	ret = -EPERM;
+			task_unlock(task);
+			read_unlock(&tasklist_lock);
+			goto out;
+		}
 		mm = task->mm;
 		if (mm) {
 			atomic_inc(&mm->mm_users);

-- 
Best Regards,
Ray
-----------------------------------------------
Ray Bryant                       raybry@sgi.com
The box said: "Requires Windows 98 or better",
           so I installed Linux.
-----------------------------------------------
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