Messages in this thread | | | From | Changli Gao <> | Date | Fri, 9 Apr 2010 18:49:12 +0800 | Subject | Re: [Patch 1/3] sysctl: refactor integer handling proc code |
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On Fri, Apr 9, 2010 at 6:11 PM, Amerigo Wang <amwang@redhat.com> wrote: > > From: Octavian Purdila <opurdila@ixiacom.com> > > As we are about to add another integer handling proc function a little > bit of cleanup is in order: add a few helper functions to improve code > readability and decrease code duplication. > > In the process a bug is also fixed: if the user specifies a number > with more then 20 digits it will be interpreted as two integers > (e.g. 10000...13 will be interpreted as 100.... and 13). > > Behavior for EFAULT handling was changed as well. Previous to this > patch, when an EFAULT error occurred in the middle of a write > operation, although some of the elements were set, that was not > acknowledged to the user (by shorting the write and returning the > number of bytes accepted). EFAULT is now treated just like any other > errors by acknowledging the amount of bytes accepted. > > Signed-off-by: Octavian Purdila <opurdila@ixiacom.com> > Signed-off-by: WANG Cong <amwang@redhat.com> > Cc: Eric W. Biederman <ebiederm@xmission.com> > --- > > Index: linux-2.6/kernel/sysctl.c > =================================================================== > --- linux-2.6.orig/kernel/sysctl.c > +++ linux-2.6/kernel/sysctl.c > @@ -2040,8 +2040,148 @@ int proc_dostring(struct ctl_table *tabl > buffer, lenp, ppos); > } > > +static int proc_skip_wspace(char __user **buf, size_t *size) > +{ > + char c; > + > + while (*size) { > + if (get_user(c, *buf)) > + return -EFAULT; > + if (!isspace(c)) > + break; > + (*size)--; > + (*buf)++; > + } > + > + return 0; > +} > + > +static bool isanyof(char c, const char *v, unsigned len) > +{ > + int i; > + > + if (!len) > + return false; > + > + for (i = 0; i < len; i++) > + if (c == v[i]) > + break; > + if (i == len) > + return false; > + > + return true; > +} > + > +#define TMPBUFLEN 22 > +/** > + * proc_get_ulong - reads an ASCII formated integer from a user buffer > + * > + * @buf - user buffer > + * @size - size of the user buffer > + * @val - this is where the number will be stored > + * @neg - set to %TRUE if number is negative > + * @perm_tr - a vector which contains the allowed trailers > + * @perm_tr_len - size of the perm_tr vector > + * @tr - pointer to store the trailer character > + * > + * In case of success 0 is returned and buf and size are updated with > + * the amount of bytes read. If tr is non NULL and a trailing > + * character exist (size is non zero after returning from this > + * function) tr is updated with the trailing character. > + */ > +static int proc_get_ulong(char __user **buf, size_t *size, > + unsigned long *val, bool *neg, > + const char *perm_tr, unsigned perm_tr_len, char *tr) > +{ > + int len; > + char *p, tmp[TMPBUFLEN]; > + > + if (!*size) > + return -EINVAL; > + > + len = *size; > + if (len > TMPBUFLEN-1) > + len = TMPBUFLEN-1; > + > + if (copy_from_user(tmp, *buf, len)) > + return -EFAULT; > + > + tmp[len] = 0; > + p = tmp; > + if (*p == '-' && *size > 1) { > + *neg = 1; > + p++; > + } else > + *neg = 0;
the function name implies that it is used to parse unsigned long, so negative value should not be supported.
> + if (!isdigit(*p)) > + return -EINVAL;
It seems that ledding white space should be allowed, so this check isn't needed, and simple_strtoul can handle it.
> + > + *val = simple_strtoul(p, &p, 0); > + > + len = p - tmp; > + > + /* We don't know if the next char is whitespace thus we may accept > + * invalid integers (e.g. 1234...a) or two integers instead of one > + * (e.g. 123...1). So lets not allow such large numbers. */ > + if (len == TMPBUFLEN - 1) > + return -EINVAL; > + > + if (len < *size && perm_tr_len && !isanyof(*p, perm_tr, perm_tr_len)) > + return -EINVAL;
is strspn() better?
> + > + if (tr && (len < *size)) > + *tr = *p; > + > + *buf += len; > + *size -= len; > + > + return 0; > +} > + > +/** > + * proc_put_ulong - coverts an integer to a decimal ASCII formated string > + * > + * @buf - the user buffer > + * @size - the size of the user buffer > + * @val - the integer to be converted > + * @neg - sign of the number, %TRUE for negative > + * @first - if %FALSE will insert a separator character before the number > + * @separator - the separator character > + * > + * In case of success 0 is returned and buf and size are updated with > + * the amount of bytes read. > + */ > +static int proc_put_ulong(char __user **buf, size_t *size, unsigned long val, > + bool neg, bool first, char separator) > +{ > + int len; > + char tmp[TMPBUFLEN], *p = tmp; > + > + if (!first) > + *p++ = separator; > + sprintf(p, "%s%lu", neg ? "-" : "", val);
negative should not be supported too.
> + len = strlen(tmp); > + if (len > *size) > + len = *size; > + if (copy_to_user(*buf, tmp, len)) > + return -EFAULT; > + *size -= len; > + *buf += len; > + return 0; > +} > +#undef TMPBUFLEN > + > +static int proc_put_char(char __user **buf, size_t *size, char c) > +{ > + if (*size) { > + if (put_user(c, *buf)) > + return -EFAULT; > + (*size)--, (*buf)++; > + } > + return 0; > +} > > -static int do_proc_dointvec_conv(int *negp, unsigned long *lvalp, > +static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp, > int *valp, > int write, void *data) > { > @@ -2050,7 +2190,7 @@ static int do_proc_dointvec_conv(int *ne > } else { > int val = *valp; > if (val < 0) { > - *negp = -1; > + *negp = 1; > *lvalp = (unsigned long)-val; > } else { > *negp = 0; > @@ -2060,20 +2200,18 @@ static int do_proc_dointvec_conv(int *ne > return 0; > } > > +static const char proc_wspace_sep[] = { ' ', '\t', '\n', 0 }; > + > static int __do_proc_dointvec(void *tbl_data, struct ctl_table *table, > - int write, void __user *buffer, > + int write, void __user *_buffer, > size_t *lenp, loff_t *ppos, > - int (*conv)(int *negp, unsigned long *lvalp, int *valp, > + int (*conv)(bool *negp, unsigned long *lvalp, int *valp, > int write, void *data), > void *data) > { > -#define TMPBUFLEN 21 > - int *i, vleft, first = 1, neg; > - unsigned long lval; > - size_t left, len; > - > - char buf[TMPBUFLEN], *p; > - char __user *s = buffer; > + int *i, vleft, first = 1, err = 0; > + size_t left; > + char __user *buffer = (char __user *) _buffer; > > if (!tbl_data || !table->maxlen || !*lenp || > (*ppos && !write)) { > @@ -2089,88 +2227,48 @@ static int __do_proc_dointvec(void *tbl_ > conv = do_proc_dointvec_conv; > > for (; left && vleft--; i++, first=0) { > - if (write) { > - while (left) { > - char c; > - if (get_user(c, s)) > - return -EFAULT; > - if (!isspace(c)) > - break; > - left--; > - s++; > - } > - if (!left) > - break; > - neg = 0; > - len = left; > - if (len > sizeof(buf) - 1) > - len = sizeof(buf) - 1; > - if (copy_from_user(buf, s, len)) > - return -EFAULT; > - buf[len] = 0; > - p = buf; > - if (*p == '-' && left > 1) { > - neg = 1; > - p++; > - } > - if (*p < '0' || *p > '9') > - break; > - > - lval = simple_strtoul(p, &p, 0); > + unsigned long lval; > + bool neg; > > - len = p-buf; > - if ((len < left) && *p && !isspace(*p)) > + if (write) { > + err = proc_skip_wspace(&buffer, &left); > + if (err) > + return err; > + err = proc_get_ulong(&buffer, &left, &lval, &neg, > + proc_wspace_sep, > + sizeof(proc_wspace_sep), NULL); > + if (err) > break; > - s += len; > - left -= len; > - > - if (conv(&neg, &lval, i, 1, data)) > + if (conv(&neg, &lval, i, 1, data)) { > + err = -EINVAL; > break; > + } > } else { > - p = buf; > - if (!first) > - *p++ = '\t'; > - > - if (conv(&neg, &lval, i, 0, data)) > + if (conv(&neg, &lval, i, 0, data)) { > + err = -EINVAL; > break; > - > - sprintf(p, "%s%lu", neg ? "-" : "", lval); > - len = strlen(buf); > - if (len > left) > - len = left; > - if(copy_to_user(s, buf, len)) > - return -EFAULT; > - left -= len; > - s += len; > - } > - } > - > - if (!write && !first && left) { > - if(put_user('\n', s)) > - return -EFAULT; > - left--, s++; > - } > - if (write) { > - while (left) { > - char c; > - if (get_user(c, s++)) > - return -EFAULT; > - if (!isspace(c)) > + } > + err = proc_put_ulong(&buffer, &left, lval, neg, first, > + '\t'); > + if (err) > break; > - left--; > } > } > + > + if (!write && !first && left && !err) > + err = proc_put_char(&buffer, &left, '\n'); > + if (write && !err) > + err = proc_skip_wspace(&buffer, &left); > if (write && first) > - return -EINVAL; > + return err ? : -EINVAL; > *lenp -= left; > *ppos += *lenp; > return 0; > -#undef TMPBUFLEN > } > > static int do_proc_dointvec(struct ctl_table *table, int write, > void __user *buffer, size_t *lenp, loff_t *ppos, > - int (*conv)(int *negp, unsigned long *lvalp, int *valp, > + int (*conv)(bool *negp, unsigned long *lvalp, int *valp, > int write, void *data), > void *data) > { > @@ -2238,8 +2336,8 @@ struct do_proc_dointvec_minmax_conv_para > int *max; > }; > > -static int do_proc_dointvec_minmax_conv(int *negp, unsigned long *lvalp, > - int *valp, > +static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp, > + int *valp, > int write, void *data) > { > struct do_proc_dointvec_minmax_conv_param *param = data; > @@ -2252,7 +2350,7 @@ static int do_proc_dointvec_minmax_conv( > } else { > int val = *valp; > if (val < 0) { > - *negp = -1; > + *negp = 1; > *lvalp = (unsigned long)-val; > } else { > *negp = 0; > @@ -2290,17 +2388,15 @@ int proc_dointvec_minmax(struct ctl_tabl > } > > static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int write, > - void __user *buffer, > + void __user *_buffer, > size_t *lenp, loff_t *ppos, > unsigned long convmul, > unsigned long convdiv) > { > -#define TMPBUFLEN 21 > - unsigned long *i, *min, *max, val; > - int vleft, first=1, neg; > - size_t len, left; > - char buf[TMPBUFLEN], *p; > - char __user *s = buffer; > + unsigned long *i, *min, *max; > + int vleft, first = 1, err = 0; > + size_t left; > + char __user *buffer = (char __user *) _buffer; > > if (!data || !table->maxlen || !*lenp || > (*ppos && !write)) { > @@ -2315,82 +2411,42 @@ static int __do_proc_doulongvec_minmax(v > left = *lenp; > > for (; left && vleft--; i++, min++, max++, first=0) { > + unsigned long val; > + > if (write) { > - while (left) { > - char c; > - if (get_user(c, s)) > - return -EFAULT; > - if (!isspace(c)) > - break; > - left--; > - s++; > - } > - if (!left) > - break; > - neg = 0; > - len = left; > - if (len > TMPBUFLEN-1) > - len = TMPBUFLEN-1; > - if (copy_from_user(buf, s, len)) > - return -EFAULT; > - buf[len] = 0; > - p = buf; > - if (*p == '-' && left > 1) { > - neg = 1; > - p++; > - } > - if (*p < '0' || *p > '9') > - break; > - val = simple_strtoul(p, &p, 0) * convmul / convdiv ; > - len = p-buf; > - if ((len < left) && *p && !isspace(*p)) > + bool neg; > + > + err = proc_skip_wspace(&buffer, &left); > + if (err) > + return err; > + err = proc_get_ulong(&buffer, &left, &val, &neg, > + proc_wspace_sep, > + sizeof(proc_wspace_sep), NULL); > + if (err) > break; > if (neg) > - val = -val; > - s += len; > - left -= len; > - > - if(neg) > continue; > if ((min && val < *min) || (max && val > *max)) > continue; > *i = val; > } else { > - p = buf; > - if (!first) > - *p++ = '\t'; > - sprintf(p, "%lu", convdiv * (*i) / convmul); > - len = strlen(buf); > - if (len > left) > - len = left; > - if(copy_to_user(s, buf, len)) > - return -EFAULT; > - left -= len; > - s += len; > - } > - } > - > - if (!write && !first && left) { > - if(put_user('\n', s)) > - return -EFAULT; > - left--, s++; > - } > - if (write) { > - while (left) { > - char c; > - if (get_user(c, s++)) > - return -EFAULT; > - if (!isspace(c)) > + val = convdiv * (*i) / convmul; > + err = proc_put_ulong(&buffer, &left, val, 0, first, > + '\t'); > + if (err) > break; > - left--; > } > } > + > + if (!write && !first && left && !err) > + err = proc_put_char(&buffer, &left, '\n'); > + if (write && !err) > + err = proc_skip_wspace(&buffer, &left); > if (write && first) > - return -EINVAL; > + return err ? : -EINVAL; > *lenp -= left; > *ppos += *lenp; > return 0; > -#undef TMPBUFLEN > } > > static int do_proc_doulongvec_minmax(struct ctl_table *table, int write, > @@ -2451,7 +2507,7 @@ int proc_doulongvec_ms_jiffies_minmax(st > } > > > -static int do_proc_dointvec_jiffies_conv(int *negp, unsigned long *lvalp, > +static int do_proc_dointvec_jiffies_conv(bool *negp, unsigned long *lvalp, > int *valp, > int write, void *data) > { > @@ -2463,7 +2519,7 @@ static int do_proc_dointvec_jiffies_conv > int val = *valp; > unsigned long lval; > if (val < 0) { > - *negp = -1; > + *negp = 1; > lval = (unsigned long)-val; > } else { > *negp = 0; > @@ -2474,7 +2530,7 @@ static int do_proc_dointvec_jiffies_conv > return 0; > } > > -static int do_proc_dointvec_userhz_jiffies_conv(int *negp, unsigned long *lvalp, > +static int do_proc_dointvec_userhz_jiffies_conv(bool *negp, unsigned long *lvalp, > int *valp, > int write, void *data) > { > @@ -2486,7 +2542,7 @@ static int do_proc_dointvec_userhz_jiffi > int val = *valp; > unsigned long lval; > if (val < 0) { > - *negp = -1; > + *negp = 1; > lval = (unsigned long)-val; > } else { > *negp = 0; > @@ -2497,7 +2553,7 @@ static int do_proc_dointvec_userhz_jiffi > return 0; > } > > -static int do_proc_dointvec_ms_jiffies_conv(int *negp, unsigned long *lvalp, > +static int do_proc_dointvec_ms_jiffies_conv(bool *negp, unsigned long *lvalp, > int *valp, > int write, void *data) > { > @@ -2507,7 +2563,7 @@ static int do_proc_dointvec_ms_jiffies_c > int val = *valp; > unsigned long lval; > if (val < 0) { > - *negp = -1; > + *negp = 1; > lval = (unsigned long)-val; > } else { > *negp = 0;
These functions have so much lines of code. I think you can make them less. Please refer to strsep().
-- Regards, Changli Gao(xiaosuo@gmail.com)
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