Add new string functions strict_strto* and convert kernel params to use them

Currently, for every sysfs node, the callers will be responsible for
implementing store operation, so many many callers are doing duplicate
things to validate input, they have the same mistakes because they are
calling simple_strtol/ul/ll/uul, especially for module params, they are
just numeric, but you can echo such values as 0x1234xxx, 07777888 and
1234aaa, for these cases, module params store operation just ignores
succesive invalid char and converts prefix part to a numeric although input
is acctually invalid.

This patch tries to fix the aforementioned issues and implements
strict_strtox serial functions, kernel/params.c uses them to strictly
validate input, so module params will reject such values as 0x1234xxxx and
returns an error:

write error: Invalid argument

Any modules which export numeric sysfs node can use strict_strtox instead of
simple_strtox to reject any invalid input.

Here are some test results:

Before applying this patch:

[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
4096
[root@yangyi-dev /]# echo 0x1000 > /sys/module/e1000/parameters/copybreak
[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
4096
[root@yangyi-dev /]# echo 0x1000g > /sys/module/e1000/parameters/copybreak
[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
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[root@yangyi-dev /]# echo 0x1000gggggggg > /sys/module/e1000/parameters/copybreak
[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
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[root@yangyi-dev /]# echo 010000 > /sys/module/e1000/parameters/copybreak
[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
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[root@yangyi-dev /]# echo 0100008 > /sys/module/e1000/parameters/copybreak
[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
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[root@yangyi-dev /]# echo 010000aaaaa > /sys/module/e1000/parameters/copybreak
[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
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[root@yangyi-dev /]#

After applying this patch:

[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
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[root@yangyi-dev /]# echo 0x1000 > /sys/module/e1000/parameters/copybreak
[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
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[root@yangyi-dev /]# echo 0x1000g > /sys/module/e1000/parameters/copybreak
-bash: echo: write error: Invalid argument
[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
4096
[root@yangyi-dev /]# echo 0x1000gggggggg > /sys/module/e1000/parameters/copybreak
-bash: echo: write error: Invalid argument
[root@yangyi-dev /]# echo 010000 > /sys/module/e1000/parameters/copybreak
[root@yangyi-dev /]# echo 0100008 > /sys/module/e1000/parameters/copybreak
-bash: echo: write error: Invalid argument
[root@yangyi-dev /]# echo 010000aaaaa > /sys/module/e1000/parameters/copybreak
-bash: echo: write error: Invalid argument
[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
4096
[root@yangyi-dev /]# echo -n 4096 > /sys/module/e1000/parameters/copybreak
[root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
4096
[root@yangyi-dev /]#

[akpm@linux-foundation.org: fix compiler warnings]
[akpm@linux-foundation.org: fix off-by-one found by tiwai@suse.de]
Signed-off-by: Yi Yang <yi.y.yang@intel.com>
Cc: Greg KH <greg@kroah.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 8f28d35867f8..2df44e773270 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -141,6 +141,10 @@ extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 extern long simple_strtol(const char *,char **,unsigned int);
 extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 extern long long simple_strtoll(const char *,char **,unsigned int);
+extern int strict_strtoul(const char *, unsigned int, unsigned long *);
+extern int strict_strtol(const char *, unsigned int, long *);
+extern int strict_strtoull(const char *, unsigned int, unsigned long long *);
+extern int strict_strtoll(const char *, unsigned int, long long *);
 extern int sprintf(char * buf, const char * fmt, ...)
 	__attribute__ ((format (printf, 2, 3)));
 extern int vsprintf(char *buf, const char *, va_list)