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: ROUTE:read ifname in rt6_info_route()

IPV6 Yuta sugiura 5 participants 8 messages Apr 16, 2009 – Apr 17, 2009

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Yuta sugiura

author
#0 lore raw

Hi,
I have a suggestion about /proc/net/IPv6_route format.
In rt6_info_route(), interface name is treated as a maximum 8 characters. But the type of (struct rt6_inf *)->u.dst.dev->name is char[IFNAMESIZ= 16] so, I think that it should change "%8s" to "%16s".

Thanks,

net/ipv6/route.c +2 -2
index 1394ddb..9ad58e7 100644
@@ -2434,7 +2434,7 @@ static int ip6_route_dev_notify(struct notifier_block *this,
 
 #ifdef CONFIG_PROC_FS
 
-#define RT6_INFO_LEN (32 + 4 + 32 + 4 + 32 + 40 + 5 + 1)
+#define RT6_INFO_LEN (32 + 4 + 32 + 4 + 32 + 48 + 5 + 1)
 
 struct rt6_proc_arg
 {

@@ -2462,7 +2462,7 @@ static int rt6_info_route(struct rt6_info *rt, void *p_arg)
 	} else {
 		seq_puts(m, "00000000000000000000000000000000");
 	}
-	seq_printf(m, " %08x %08x %08x %08x %8s\n",
+	seq_printf(m, " %08x %08x %08x %08x %16s\n",
 		   rt->rt6i_metric, atomic_read(&rt->u.dst.__refcnt),
 		   rt->u.dst.__use, rt->rt6i_flags,
 		   rt->rt6i_dev ? rt->rt6i_dev->name : "");
maintainer
#1 lore raw

From: Yuta sugiura <[email protected]>
Date: Thu, 16 Apr 2009 20:05:05 +0900

Quoted 7 lines

Hi,
I have a suggestion about /proc/net/IPv6_route format.
In rt6_info_route(), interface name is treated as a maximum 8 characters.
But the type of (struct rt6_inf *)->u.dst.dev->name is char[IFNAMESIZ= 16]
so, I think that it should change "%8s" to "%16s".

Isn't there a way to pass the field length as a paramenter to formatting functions? Then we can just pass in IFNAMESIZE as that parameter.

#2 lore raw
Quoted 11 lines · On Thu, 16 Apr 2009 04:38:00 -0700 (PDT) David Miller <[email protected]>…

From: Yuta sugiura <[email protected]>
Date: Thu, 16 Apr 2009 20:05:05 +0900

Quoted 7 lines

Hi,
I have a suggestion about /proc/net/IPv6_route format.
In rt6_info_route(), interface name is treated as a maximum 8 characters.
But the type of (struct rt6_inf *)->u.dst.dev->name is char[IFNAMESIZ= 16]
so, I think that it should change "%8s" to "%16s".

Quoted 3 lines

Isn't there a way to pass the field length as a paramenter to formatting functions? Then we can just pass in IFNAMESIZE as that parameter.

	seq_printf(m, " %08x %08x %08x %08x %*s\n"
                   rt->rt6i_metric, atomic_read(&rt->u.dst.__refcnt),

rt->u.dst.__use, rt->rt6i_flags, IFNAMESIZE,
rt->rt6i_dev ? rt->rt6i_dev->name : "")

#3 lore raw
Quoted 19 lines · Stephen Hemminger
Quoted 10 lines · On Thu, 16 Apr 2009 04:38:00 -0700 (PDT) David Miller <[email protected]>…

From: Yuta sugiura <[email protected]>
Date: Thu, 16 Apr 2009 20:05:05 +0900

Quoted 7 lines

Hi,
I have a suggestion about /proc/net/IPv6_route format.
In rt6_info_route(), interface name is treated as a maximum 8 characters.
But the type of (struct rt6_inf *)->u.dst.dev->name is char[IFNAMESIZ= 16]
so, I think that it should change "%8s" to "%16s".

Quoted 3 lines

Isn't there a way to pass the field length as a paramenter to formatting functions? Then we can just pass in IFNAMESIZE as that parameter.

	seq_printf(m, " %08x %08x %08x %08x %*s\n"
                   rt->rt6i_metric, atomic_read(&rt->u.dst.__refcnt),

Review

Quoted 3 lines
(quoted diff) +0 -0
 		   rt->u.dst.__use, rt->rt6i_flags,
                   IFNAMESIZE, 
 		   rt->rt6i_dev ? rt->rt6i_dev->name : "")

Does the kernel actually truncate an interface name more than 8 chars long in the original version? I did a quick test in userspace and found that

	printf("%*s\n", 1, "foo");

prints:

foo

I think the width specifier is used for *minimum* width, not maximum.

-Brian

#4 lore raw
In reply to Stephen Hemminger
Quoted 20 lines · Stephen Hemminger
Quoted 11 lines · On Thu, 16 Apr 2009 04:38:00 -0700 (PDT) David Miller <[email protected]>…

From: Yuta sugiura <[email protected]>
Date: Thu, 16 Apr 2009 20:05:05 +0900

Quoted 7 lines

Hi,
I have a suggestion about /proc/net/IPv6_route format.
In rt6_info_route(), interface name is treated as a maximum 8 characters.
But the type of (struct rt6_inf *)->u.dst.dev->name is char[IFNAMESIZ= 16]
so, I think that it should change "%8s" to "%16s".

Quoted 3 lines

Isn't there a way to pass the field length as a paramenter to formatting functions? Then we can just pass in IFNAMESIZE as that parameter.

	seq_printf(m, " %08x %08x %08x %08x %*s\n"
                   rt->rt6i_metric, atomic_read(&rt->u.dst.__refcnt),

Review

Quoted 3 lines
(quoted diff) +0 -0
 		   rt->u.dst.__use, rt->rt6i_flags,
                   IFNAMESIZE, 
 		   rt->rt6i_dev ? rt->rt6i_dev->name : "")

Actually since it is the last item on the line a field width does not make much sense, and omitting it would print the name left justified.

(And RT6_INFO_LEN is not used any more.)

Andreas.

Signature · 3 lines
Andreas Schwab, [email protected]
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."
#5 lore raw
Quoted 26 lines · On Thu, 16 Apr 2009 18:47:04 +0200 Andreas Schwab <[email protected]> wrote:
Quoted 20 lines · Stephen Hemminger
Quoted 11 lines · On Thu, 16 Apr 2009 04:38:00 -0700 (PDT) David Miller <[email protected]>…

From: Yuta sugiura <[email protected]>
Date: Thu, 16 Apr 2009 20:05:05 +0900

Quoted 7 lines

Hi,
I have a suggestion about /proc/net/IPv6_route format.
In rt6_info_route(), interface name is treated as a maximum 8 characters.
But the type of (struct rt6_inf *)->u.dst.dev->name is char[IFNAMESIZ= 16]
so, I think that it should change "%8s" to "%16s".

Quoted 3 lines

Isn't there a way to pass the field length as a paramenter to formatting functions? Then we can just pass in IFNAMESIZE as that parameter.

	seq_printf(m, " %08x %08x %08x %08x %*s\n"
                   rt->rt6i_metric, atomic_read(&rt->u.dst.__refcnt),

Review

Quoted 3 lines
(quoted diff) +0 -0
 		   rt->u.dst.__use, rt->rt6i_flags,
                   IFNAMESIZE, 
 		   rt->rt6i_dev ? rt->rt6i_dev->name : "")
Quoted 7 lines

Actually since it is the last item on the line a field width does not make much sense, and omitting it would print the name left justified.

(And RT6_INFO_LEN is not used any more.)

Andreas.

The issue is what happens if name is not null terminated. in this case I bet the kernel already handles that.

author
#6 lore raw

Thank you for respons to my e-mail.
I read net-snmp's patch as reference.
How about this method?

Quoted 36 lines · Stephen Hemminger
Quoted 32 lines · On Thu, 16 Apr 2009 18:47:04 +0200 Andreas Schwab <[email protected]> wrote:
Quoted 23 lines · Stephen Hemminger
Quoted 12 lines · On Thu, 16 Apr 2009 04:38:00 -0700 (PDT) David Miller <[email protected]>…

From: Yuta sugiura <[email protected]>
Date: Thu, 16 Apr 2009 20:05:05 +0900

Quoted 8 lines

Hi,
I have a suggestion about /proc/net/IPv6_route format.
In rt6_info_route(), interface name is treated as a maximum 8 characters.
But the type of (struct rt6_inf *)->u.dst.dev->name is char[IFNAMESIZ= 16]
so, I think that it should change "%8s" to "%16s".

Quoted 4 lines

Isn't there a way to pass the field length as a paramenter to formatting functions? Then we can just pass in IFNAMESIZE as that parameter.

	seq_printf(m, " %08x %08x %08x %08x %*s\n"
                   rt->rt6i_metric, atomic_read(&rt->u.dst.__refcnt),

Review

Quoted 3 lines
(quoted diff) +0 -0
 		   rt->u.dst.__use, rt->rt6i_flags,
                   IFNAMESIZE, 
 		   rt->rt6i_dev ? rt->rt6i_dev->name : "")

Actually since it is the last item on the line a field width does not make much sense, and omitting it would print the name left justified.

Quoted 10 lines
Quoted 5 lines

(And RT6_INFO_LEN is not used any more.)

Andreas.

The issue is what happens if name is not null terminated. in this case I bet the kernel already handles that.

net/ipv6/route.c +4 -2
index 1394ddb..a532dda 100644
@@ -2434,7 +2434,8 @@ static int ip6_route_dev_notify(struct notifier_block *this,
 
 #ifdef CONFIG_PROC_FS
 
-#define RT6_INFO_LEN (32 + 4 + 32 + 4 + 32 + 40 + 5 + 1)
+#define RT6_INFO_LEN (32 + 4 + 32 + 4 + 32 + 48 + 5 + 1)
+#define RT6_VAL_TO_STR(s) #s
 
 struct rt6_proc_arg
 {

@@ -2462,7 +2463,8 @@ static int rt6_info_route(struct rt6_info *rt, void *p_arg)
 	} else {
 		seq_puts(m, "00000000000000000000000000000000");
 	}
-	seq_printf(m, " %08x %08x %08x %08x %8s\n",
+	seq_printf(m, " %08x %08x %08x %08x %"
+		   RT6_VAL_TO_STR(IFNAMSIZ) "s\n",
 		   rt->rt6i_metric, atomic_read(&rt->u.dst.__refcnt),
 		   rt->u.dst.__use, rt->rt6i_flags,
 		   rt->rt6i_dev ? rt->rt6i_dev->name : "");
#7 lore raw
In reply to Stephen Hemminger
Quoted 1 line · Stephen Hemminger

The issue is what happens if name is not null terminated.

That cannot happen. And a field width would not help anyway.

Andreas.

Signature · 3 lines
Andreas Schwab, [email protected]
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."