1 files changed, 28 insertions, 4 deletions

diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index 7e5eb7554990..dcb19592761e 100644
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -34,6 +34,8 @@
  *    Sridhar Samudrala     <sri@us.ibm.com>
  */
 
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <net/sctp/structs.h>
 #include <net/sctp/sctp.h>
 #include <linux/sysctl.h>
@@ -46,6 +48,11 @@ static int sack_timer_min = 1;
 static int sack_timer_max = 500;
 static int addr_scope_max = 3; /* check sctp_scope_policy_t in include/net/sctp/constants.h for max entries */
 static int rwnd_scale_max = 16;
+static int rto_alpha_min = 0;
+static int rto_beta_min = 0;
+static int rto_alpha_max = 1000;
+static int rto_beta_max = 1000;
+
 static unsigned long max_autoclose_min = 0;
 static unsigned long max_autoclose_max =
         (MAX_SCHEDULE_TIMEOUT / HZ > UINT_MAX)
@@ -64,6 +71,9 @@ static int proc_sctp_do_rto_min(struct ctl_table *ctl, int write,
 static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write,
                                 void __user *buffer, size_t *lenp,
                                 loff_t *ppos);
+static int proc_sctp_do_alpha_beta(struct ctl_table *ctl, int write,
+                                   void __user *buffer, size_t *lenp,
+                                   loff_t *ppos);
 static int proc_sctp_do_auth(struct ctl_table *ctl, int write,
                              void __user *buffer, size_t *lenp,
                              loff_t *ppos);
@@ -126,15 +136,19 @@ static struct ctl_table sctp_net_table[] = {
                 .procname       = "rto_alpha_exp_divisor",
                 .data           = &init_net.sctp.rto_alpha,
                 .maxlen         = sizeof(int),
-                .mode           = 0444,
-                .proc_handler   = proc_dointvec,
+                .mode           = 0644,
+                .proc_handler   = proc_sctp_do_alpha_beta,
+                .extra1         = &rto_alpha_min,
+                .extra2         = &rto_alpha_max,
         },
         {
                 .procname       = "rto_beta_exp_divisor",
                 .data           = &init_net.sctp.rto_beta,
                 .maxlen         = sizeof(int),
-                .mode           = 0444,
-                .proc_handler   = proc_dointvec,
+                .mode           = 0644,
+                .proc_handler   = proc_sctp_do_alpha_beta,
+                .extra1         = &rto_beta_min,
+                .extra2         = &rto_beta_max,
         },
         {
                 .procname       = "max_burst",
@@ -403,6 +417,16 @@ static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write,
         return ret;
 }
 
+static int proc_sctp_do_alpha_beta(struct ctl_table *ctl, int write,
+                                   void __user *buffer, size_t *lenp,
+                                   loff_t *ppos)
+{
+        pr_warn_once("Changing rto_alpha or rto_beta may lead to "
+                     "suboptimal rtt/srtt estimations!\n");
+
+        return proc_dointvec_minmax(ctl, write, buffer, lenp, ppos);
+}
+
 static int proc_sctp_do_auth(struct ctl_table *ctl, int write,
                              void __user *buffer, size_t *lenp,
                              loff_t *ppos)