You might have more than one process which is restored which wants the
same pid. A container is a group of processes which share namespace.
In this case, pid namespace. The idea for now is that everything is
in "container 0" unless otherwise specified.
This /proc file allows a task to set the container id of any of its
children.
This is mostly a hack for now, to demonstrate what can be done.
---
linux-2.6.14-rc5-dave/fs/proc/base.c | 58 ++++++++++++++++++++++++++++
linux-2.6.14-rc5-dave/include/linux/sched.h | 2
2 files changed, 60 insertions(+)
diff -puN fs/proc/base.c~C1-proc-interface-to-child_container_id fs/proc/base.c
--- linux-2.6.14-rc5/fs/proc/base.c~C1-proc-interface-to-child_container_id
2005-10-24 17:55:40.000000000 +0200
+++ linux-2.6.14-rc5-dave/fs/proc/base.c 2005-10-24 17:55:40.000000000
+0200
@@ -164,6 +164,8 @@ enum pid_directory_inos {
#endif
PROC_TID_OOM_SCORE,
PROC_TID_OOM_ADJUST,
+ PROC_TID_CHILD_CONTAINER_ID,
+ PROC_TGID_CHILD_CONTAINER_ID,
/* Add new entries before this */
PROC_TID_FD_DIR = 0x8000, /* 0x8000-0xffff */
@@ -216,6 +218,7 @@ static struct pid_entry tgid_base_stuff[
#endif
E(PROC_TGID_OOM_SCORE, "oom_score",S_IFREG|S_IRUGO),
E(PROC_TGID_OOM_ADJUST,"oom_adj", S_IFREG|S_IRUGO|S_IWUSR),
+ E(PROC_TGID_CHILD_CONTAINER_ID, "child_container_id",
S_IFREG|S_IRUGO|S_IWUSR),
#ifdef CONFIG_AUDITSYSCALL
E(PROC_TGID_LOGINUID, "loginuid", S_IFREG|S_IWUSR|S_IRUGO),
#endif
@@ -258,6 +261,7 @@ static struct pid_entry tid_base_stuff[]
#endif
E(PROC_TID_OOM_SCORE, "oom_score",S_IFREG|S_IRUGO),
E(PROC_TID_OOM_ADJUST, "oom_adj", S_IFREG|S_IRUGO|S_IWUSR),
+ E(PROC_TID_CHILD_CONTAINER_ID, "child_container_id",
S_IFREG|S_IRUGO|S_IWUSR),
#ifdef CONFIG_AUDITSYSCALL
E(PROC_TID_LOGINUID, "loginuid", S_IFREG|S_IWUSR|S_IRUGO),
#endif
@@ -910,6 +914,56 @@ static struct file_operations proc_oom_a
.write = oom_adjust_write,
};
+static ssize_t proc_child_container_id_read(struct file *file, char __user
*buf,
+ size_t count, loff_t *ppos)
+{
+ struct task_struct *task = proc_task(file->f_dentry->d_inode);
+ char buffer[8];
+ size_t len;
+ int child_container_id = task->child_container_id;
+ loff_t __ppos = *ppos;
+
+ len = sprintf(buffer, "%i\n", child_container_id);
+ if (__ppos >= len)
+ return 0;
+ if (count > len-__ppos)
+ count = len-__ppos;
+ if (copy_to_user(buf, buffer + __ppos, count))
+ return -EFAULT;
+ *ppos = __ppos + count;
+ return count;
+}
+
+static ssize_t proc_child_container_id_write(struct file *file, const char
__user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct task_struct *task = proc_task(file->f_dentry->d_inode);
+ char buffer[8], *end;
+ int child_container_id;
+
+ if (!capable(CAP_SYS_RESOURCE))
+ return -EPERM;
+ memset(buffer, 0, 8);
+ if (count > 6)
+ count = 6;
+ if (copy_from_user(buffer, buf, count))
+ return -EFAULT;
+ child_container_id = simple_strtol(buffer, &end, 0);
+ if (child_container_id < 0 || child_container_id > MAX_CONTAINER_ID)
+ return -EINVAL;
+ if (*end == '\n')
+ end++;
+ task->child_container_id = child_container_id;
+ if (end - buffer == 0)
+ return -EIO;
+ return end - buffer;
+}
+
+static struct file_operations proc_child_container_id_operations = {
+ .read = proc_child_container_id_read,
+ .write = proc_child_container_id_write,
+};
+
static struct inode_operations proc_mem_inode_operations = {
.permission = proc_permission,
};
@@ -1748,6 +1802,10 @@ static struct dentry *proc_pident_lookup
case PROC_TGID_OOM_ADJUST:
inode->i_fop = &proc_oom_adjust_operations;
break;
+ case PROC_TID_CHILD_CONTAINER_ID:
+ case PROC_TGID_CHILD_CONTAINER_ID:
+ inode->i_fop = &proc_child_container_id_operations;
+ break;
#ifdef CONFIG_AUDITSYSCALL
case PROC_TID_LOGINUID:
case PROC_TGID_LOGINUID:
diff -puN include/linux/sched.h~C1-proc-interface-to-child_container_id
include/linux/sched.h
---
linux-2.6.14-rc5/include/linux/sched.h~C1-proc-interface-to-child_container_id
2005-10-24 17:55:40.000000000 +0200
+++ linux-2.6.14-rc5-dave/include/linux/sched.h 2005-10-24 17:55:40.000000000
+0200
@@ -726,6 +726,8 @@ struct task_struct {
/* process credentials */
uid_t uid,euid,suid,fsuid;
gid_t gid,egid,sgid,fsgid;
+#define MAX_CONTAINER_ID 1024
+ int child_container_id;
struct group_info *group_info;
kernel_cap_t cap_effective, cap_inheritable, cap_permitted;
unsigned keep_capabilities:1;
_
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