sctp: add check rto_min and rto_max in sysctl

rto_min should be smaller than rto_max while rto_max should be larger
than rto_min. Add two proc_handler for the checking.

Suggested-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: Wang Weidong <wangweidong1@huawei.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 65 insertions, 4 deletions

diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index 6b36561a1b3b..43b5e3243871 100644
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -61,6 +61,13 @@ static int proc_sctp_do_hmac_alg(struct ctl_table *ctl,
                                 void __user *buffer, size_t *lenp,
 
                                 loff_t *ppos);
+static int proc_sctp_do_rto_min(struct ctl_table *ctl, int write,
+                                void __user *buffer, size_t *lenp,
+                                loff_t *ppos);
+static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write,
+                                void __user *buffer, size_t *lenp,
+                                loff_t *ppos);
+
 static struct ctl_table sctp_table[] = {
         {
                 .procname       = "sctp_mem",
@@ -102,17 +109,17 @@ static struct ctl_table sctp_net_table[] = {
                 .data           = &init_net.sctp.rto_min,
                 .maxlen         = sizeof(unsigned int),
                 .mode           = 0644,
-                .proc_handler   = proc_dointvec_minmax,
+                .proc_handler   = proc_sctp_do_rto_min,
                 .extra1         = &one,
-                .extra2         = &timer_max
+                .extra2         = &init_net.sctp.rto_max
         },
         {
                 .procname       = "rto_max",
                 .data           = &init_net.sctp.rto_max,
                 .maxlen         = sizeof(unsigned int),
                 .mode           = 0644,
-                .proc_handler   = proc_dointvec_minmax,
-                .extra1         = &one,
+                .proc_handler   = proc_sctp_do_rto_max,
+                .extra1         = &init_net.sctp.rto_min,
                 .extra2         = &timer_max
         },
         {
@@ -342,6 +349,60 @@ static int proc_sctp_do_hmac_alg(struct ctl_table *ctl,
         return ret;
 }
 
+static int proc_sctp_do_rto_min(struct ctl_table *ctl, int write,
+                                void __user *buffer, size_t *lenp,
+                                loff_t *ppos)
+{
+        struct net *net = current->nsproxy->net_ns;
+        int new_value;
+        struct ctl_table tbl;
+        unsigned int min = *(unsigned int *) ctl->extra1;
+        unsigned int max = *(unsigned int *) ctl->extra2;
+        int ret;
+
+        memset(&tbl, 0, sizeof(struct ctl_table));
+        tbl.maxlen = sizeof(unsigned int);
+
+        if (write)
+                tbl.data = &new_value;
+        else
+                tbl.data = &net->sctp.rto_min;
+        ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
+        if (write) {
+                if (ret || new_value > max || new_value < min)
+                        return -EINVAL;
+                net->sctp.rto_min = new_value;
+        }
+        return ret;
+}
+
+static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write,
+                                void __user *buffer, size_t *lenp,
+                                loff_t *ppos)
+{
+        struct net *net = current->nsproxy->net_ns;
+        int new_value;
+        struct ctl_table tbl;
+        unsigned int min = *(unsigned int *) ctl->extra1;
+        unsigned int max = *(unsigned int *) ctl->extra2;
+        int ret;
+
+        memset(&tbl, 0, sizeof(struct ctl_table));
+        tbl.maxlen = sizeof(unsigned int);
+
+        if (write)
+                tbl.data = &new_value;
+        else
+                tbl.data = &net->sctp.rto_max;
+        ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
+        if (write) {
+                if (ret || new_value > max || new_value < min)
+                        return -EINVAL;
+                net->sctp.rto_max = new_value;
+        }
+        return ret;
+}
+
 int sctp_sysctl_net_register(struct net *net)
 {
         struct ctl_table *table;