sysctl: move cad_pid into kernel/pid.c

Move cad_pid as well as supporting function proc_do_cad_pid into
kernel/pic.c. Replaced call to __do_proc_dointvec with proc_dointvec
inside proc_do_cad_pid which requires the copy of the ctl_table to
handle the temp value.

This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.

Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/kernel/pid.c b/kernel/pid.c
index 8317bcbc7cf7..9ea0db2cdc29 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -713,6 +713,29 @@ static struct ctl_table_root pid_table_root = {
 	.set_ownership	= pid_table_root_set_ownership,
 };
 
+static int proc_do_cad_pid(const struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos)
+{
+	struct pid *new_pid;
+	pid_t tmp_pid;
+	int r;
+	struct ctl_table tmp_table = *table;
+
+	tmp_pid = pid_vnr(cad_pid);
+	tmp_table.data = &tmp_pid;
+
+	r = proc_dointvec(&tmp_table, write, buffer, lenp, ppos);
+	if (r || !write)
+		return r;
+
+	new_pid = find_get_pid(tmp_pid);
+	if (!new_pid)
+		return -ESRCH;
+
+	put_pid(xchg(&cad_pid, new_pid));
+	return 0;
+}
+
 static const struct ctl_table pid_table[] = {
 	{
 		.procname	= "pid_max",
@@ -723,6 +746,14 @@ static const struct ctl_table pid_table[] = {
 		.extra1		= &pid_max_min,
 		.extra2		= &pid_max_max,
 	},
+#ifdef CONFIG_PROC_SYSCTL
+	{
+		.procname	= "cad_pid",
+		.maxlen		= sizeof(int),
+		.mode		= 0600,
+		.proc_handler	= proc_do_cad_pid,
+	},
+#endif
 };
 #endif