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Message-Id: <200610051249.07856.reinette.chatre@linux.intel.com>
Date: Thu, 5 Oct 2006 12:49:07 -0700
From: Reinette Chatre <reinette.chatre@...ux.intel.com>
To: Andrew Morton <akpm@...l.org>
Cc: Inaky Perez-Gonzalez <inaky@...ux.intel.com>,
Joe Korty <joe.korty@...r.com>, Paul Jackson <pj@....com>,
linux-kernel@...r.kernel.org, reinette.chatre@...ux.intel.com
Subject: [PATCH] bitmap: parse kernel and user buffers
lib/bitmap.c:bitmap_parse() is a library function that received as
input a user buffer. This seemed to have originated from the way the
write_proc function of the /proc filesystem operates.
This has been reworked as follows:
- don't use kmalloc
- eliminates a lot of get_user overhead by performing one access_ok
before using __get_user
- access kernel buffer using __get_user(kernel_address)
This function will be useful for other uses as well; for example,
taking input for /sysfs instead of /proc, so it was changed to accept
kernel buffers. We have this use for the Linux UWB project, as part as
the upcoming bandwidth allocator code.
Only a few routines used this function and they were changed too.
Signed-off-by: Reinette Chatre <reinette.chatre@...ux.intel.com>
---
This is an updated version of patch
bitmap-bitmap_parse-takes-a-kernel-buffer-instead-of-a-user-buffer.patch
With the usage of access_ok() before __get_user(), is it still necessary
to check the return code of __get_user? We currently do this.
include/linux/bitmap.h | 7 +++++--
include/linux/cpumask.h | 14 +++++++-------
include/linux/nodemask.h | 14 +++++++-------
kernel/irq/proc.c | 2 +-
kernel/profile.c | 2 +-
lib/bitmap.c | 47 +++++++++++++++++++++++++++++++++++++++--------
6 files changed, 60 insertions(+), 26 deletions(-)
diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/include/linux/bitmap.h linux-2.6.hg/include/linux/bitmap.h
--- linux-2.6.hg.vanilla/include/linux/bitmap.h 2006-10-02 14:04:35.000000000 -0700
+++ linux-2.6.hg/include/linux/bitmap.h 2006-10-05 11:35:51.000000000 -0700
@@ -46,7 +46,8 @@
* bitmap_remap(dst, src, old, new, nbits) *dst = map(old, new)(src)
* bitmap_bitremap(oldbit, old, new, nbits) newbit = map(old, new)(oldbit)
* bitmap_scnprintf(buf, len, src, nbits) Print bitmap src to buf
- * bitmap_parse(ubuf, ulen, dst, nbits) Parse bitmap dst from user buf
+ * bitmap_parse(buf, buflen, dst, nbits) Parse bitmap dst from buf
+ * bitmap_parse_user(ubuf, ulen, dst, nbits) Parse bitmap dst from user buf
* bitmap_scnlistprintf(buf, len, src, nbits) Print bitmap src as list to buf
* bitmap_parselist(buf, dst, nbits) Parse bitmap dst from list
* bitmap_find_free_region(bitmap, bits, order) Find and allocate bit region
@@ -106,7 +107,9 @@ extern int __bitmap_weight(const unsigne
extern int bitmap_scnprintf(char *buf, unsigned int len,
const unsigned long *src, int nbits);
-extern int bitmap_parse(const char __user *ubuf, unsigned int ulen,
+extern int bitmap_parse(const char *buf, unsigned int buflen,
+ unsigned long *dst, int nbits);
+extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
unsigned long *dst, int nbits);
extern int bitmap_scnlistprintf(char *buf, unsigned int len,
const unsigned long *src, int nbits);
diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/lib/bitmap.c linux-2.6.hg/lib/bitmap.c
--- linux-2.6.hg.vanilla/lib/bitmap.c 2006-10-02 14:04:39.000000000 -0700
+++ linux-2.6.hg/lib/bitmap.c 2006-10-05 11:40:40.000000000 -0700
@@ -317,8 +317,8 @@ EXPORT_SYMBOL(bitmap_scnprintf);
/**
* bitmap_parse - convert an ASCII hex string into a bitmap.
- * @ubuf: pointer to buffer in user space containing string.
- * @ubuflen: buffer size in bytes. If string is smaller than this
+ * @buf: pointer to buffer containing string.
+ * @buflen: buffer size in bytes. If string is smaller than this
* then it must be terminated with a \0.
* @maskp: pointer to bitmap array that will contain result.
* @nmaskbits: size of bitmap, in bits.
@@ -329,9 +329,15 @@ EXPORT_SYMBOL(bitmap_scnprintf);
* then leading 0-bits are prepended. %-EINVAL is returned for illegal
* characters and for grouping errors such as "1,,5", ",44", "," and "".
* Leading and trailing whitespace accepted, but not embedded whitespace.
+ *
+ * This function is used by a wrapper function (bitmap_parse_user())
+ * that tests (using access_ok()) a user buffer before passing it here for
+ * parsing. We need to use __get_user(). When provided with a kernel
+ * buffer we are thus using __get_user(kernel_address), which works OK and
+ * is used in several places in the core kernel.
*/
-int bitmap_parse(const char __user *ubuf, unsigned int ubuflen,
- unsigned long *maskp, int nmaskbits)
+int bitmap_parse(const char *buf, unsigned int buflen,
+ unsigned long *maskp, int nmaskbits)
{
int c, old_c, totaldigits, ndigits, nchunks, nbits;
u32 chunk;
@@ -343,11 +349,11 @@ int bitmap_parse(const char __user *ubuf
chunk = ndigits = 0;
/* Get the next chunk of the bitmap */
- while (ubuflen) {
+ while (buflen) {
old_c = c;
- if (get_user(c, ubuf++))
+ if (__get_user(c, buf++))
return -EFAULT;
- ubuflen--;
+ buflen--;
if (isspace(c))
continue;
@@ -388,12 +394,37 @@ int bitmap_parse(const char __user *ubuf
nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
if (nbits > nmaskbits)
return -EOVERFLOW;
- } while (ubuflen && c == ',');
+ } while (buflen && c == ',');
return 0;
}
EXPORT_SYMBOL(bitmap_parse);
+/**
+ * bitmap_parse_user()
+ *
+ * @ubuf: pointer to user buffer containing string.
+ * @ulen: buffer size in bytes. If string is smaller than this
+ * then it must be terminated with a \0.
+ * @maskp: pointer to bitmap array that will contain result.
+ * @nmaskbits: size of bitmap, in bits.
+ *
+ * Wrapper for bitmap_parse(), providing it with user buffer.
+ *
+ * We cannot have this as an inline function in bitmap.h because it needs
+ * linux/uaccess.h to get the access_ok() declaration and this causes
+ * cyclic dependencies.
+ */
+int bitmap_parse_user(const char __user *ubuf,
+ unsigned int ulen, unsigned long *maskp,
+ int nmaskbits)
+{
+ if (!access_ok(VERIFY_READ, ubuf, ulen))
+ return -EFAULT;
+ return bitmap_parse((const char *)ubuf, ulen, maskp, nmaskbits);
+}
+EXPORT_SYMBOL(bitmap_parse_user);
+
/*
* bscnl_emit(buf, buflen, rbot, rtop, bp)
*
diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/include/linux/cpumask.h linux-2.6.hg/include/linux/cpumask.h
--- linux-2.6.hg.vanilla/include/linux/cpumask.h 2006-10-02 14:04:35.000000000 -0700
+++ linux-2.6.hg/include/linux/cpumask.h 2006-10-04 09:07:47.000000000 -0700
@@ -8,8 +8,8 @@
* See detailed comments in the file linux/bitmap.h describing the
* data type on which these cpumasks are based.
*
- * For details of cpumask_scnprintf() and cpumask_parse(),
- * see bitmap_scnprintf() and bitmap_parse() in lib/bitmap.c.
+ * For details of cpumask_scnprintf() and cpumask_parse_user(),
+ * see bitmap_scnprintf() and bitmap_parse_user() in lib/bitmap.c.
* For details of cpulist_scnprintf() and cpulist_parse(), see
* bitmap_scnlistprintf() and bitmap_parselist(), also in bitmap.c.
* For details of cpu_remap(), see bitmap_bitremap in lib/bitmap.c
@@ -49,7 +49,7 @@
* unsigned long *cpus_addr(mask) Array of unsigned long's in mask
*
* int cpumask_scnprintf(buf, len, mask) Format cpumask for printing
- * int cpumask_parse(ubuf, ulen, mask) Parse ascii string as cpumask
+ * int cpumask_parse_user(ubuf, ulen, mask) Parse ascii string as cpumask
* int cpulist_scnprintf(buf, len, mask) Format cpumask as list for printing
* int cpulist_parse(buf, map) Parse ascii string as cpulist
* int cpu_remap(oldbit, old, new) newbit = map(old, new)(oldbit)
@@ -273,12 +273,12 @@ static inline int __cpumask_scnprintf(ch
return bitmap_scnprintf(buf, len, srcp->bits, nbits);
}
-#define cpumask_parse(ubuf, ulen, dst) \
- __cpumask_parse((ubuf), (ulen), &(dst), NR_CPUS)
-static inline int __cpumask_parse(const char __user *buf, int len,
+#define cpumask_parse_user(ubuf, ulen, dst) \
+ __cpumask_parse_user((ubuf), (ulen), &(dst), NR_CPUS)
+static inline int __cpumask_parse_user(const char __user *buf, int len,
cpumask_t *dstp, int nbits)
{
- return bitmap_parse(buf, len, dstp->bits, nbits);
+ return bitmap_parse_user(buf, len, dstp->bits, nbits);
}
#define cpulist_scnprintf(buf, len, src) \
diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/kernel/irq/proc.c linux-2.6.hg/kernel/irq/proc.c
--- linux-2.6.hg.vanilla/kernel/irq/proc.c 2006-10-02 14:04:38.000000000 -0700
+++ linux-2.6.hg/kernel/irq/proc.c 2006-10-04 09:05:55.000000000 -0700
@@ -57,7 +57,7 @@ static int irq_affinity_write_proc(struc
if (!irq_desc[irq].chip->set_affinity || no_irq_affinity)
return -EIO;
- err = cpumask_parse(buffer, count, new_value);
+ err = cpumask_parse_user(buffer, count, new_value);
if (err)
return err;
diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/kernel/profile.c linux-2.6.hg/kernel/profile.c
--- linux-2.6.hg.vanilla/kernel/profile.c 2006-10-02 14:04:38.000000000 -0700
+++ linux-2.6.hg/kernel/profile.c 2006-10-04 09:45:01.000000000 -0700
@@ -396,7 +396,7 @@ static int prof_cpu_mask_write_proc (str
unsigned long full_count = count, err;
cpumask_t new_value;
- err = cpumask_parse(buffer, count, new_value);
+ err = cpumask_parse_user(buffer, count, new_value);
if (err)
return err;
diff -uprN -X linux-2.6.hg.vanilla/Documentation/dontdiff linux-2.6.hg.vanilla/include/linux/nodemask.h linux-2.6.hg/include/linux/nodemask.h
--- linux-2.6.hg.vanilla/include/linux/nodemask.h 2006-10-03 16:58:10.000000000 -0700
+++ linux-2.6.hg/include/linux/nodemask.h 2006-10-04 09:19:52.000000000 -0700
@@ -8,8 +8,8 @@
* See detailed comments in the file linux/bitmap.h describing the
* data type on which these nodemasks are based.
*
- * For details of nodemask_scnprintf() and nodemask_parse(),
- * see bitmap_scnprintf() and bitmap_parse() in lib/bitmap.c.
+ * For details of nodemask_scnprintf() and nodemask_parse_user(),
+ * see bitmap_scnprintf() and bitmap_parse_user() in lib/bitmap.c.
* For details of nodelist_scnprintf() and nodelist_parse(), see
* bitmap_scnlistprintf() and bitmap_parselist(), also in bitmap.c.
* For details of node_remap(), see bitmap_bitremap in lib/bitmap.c.
@@ -51,7 +51,7 @@
* unsigned long *nodes_addr(mask) Array of unsigned long's in mask
*
* int nodemask_scnprintf(buf, len, mask) Format nodemask for printing
- * int nodemask_parse(ubuf, ulen, mask) Parse ascii string as nodemask
+ * int nodemask_parse_user(ubuf, ulen, mask) Parse ascii string as nodemask
* int nodelist_scnprintf(buf, len, mask) Format nodemask as list for printing
* int nodelist_parse(buf, map) Parse ascii string as nodelist
* int node_remap(oldbit, old, new) newbit = map(old, new)(oldbit)
@@ -288,12 +288,12 @@ static inline int __nodemask_scnprintf(c
return bitmap_scnprintf(buf, len, srcp->bits, nbits);
}
-#define nodemask_parse(ubuf, ulen, dst) \
- __nodemask_parse((ubuf), (ulen), &(dst), MAX_NUMNODES)
-static inline int __nodemask_parse(const char __user *buf, int len,
+#define nodemask_parse_user(ubuf, ulen, dst) \
+ __nodemask_parse_user((ubuf), (ulen), &(dst), MAX_NUMNODES)
+static inline int __nodemask_parse_user(const char __user *buf, int len,
nodemask_t *dstp, int nbits)
{
- return bitmap_parse(buf, len, dstp->bits, nbits);
+ return bitmap_parse_user(buf, len, dstp->bits, nbits);
}
#define nodelist_scnprintf(buf, len, src) \
-
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