The patch titled
Subject: sysctl: add range clamping intvec helper functions
has been added to the -mm tree. Its filename is
sysctl-add-range-clamping-intvec-helper-functions.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/sysctl-add-range-clamping-intvec-helper-functions.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/sysctl-add-range-clamping-intvec-helper-functions.patch
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------------------------------------------------------
From: Waiman Long <longman@xxxxxxxxxx>
Subject: sysctl: add range clamping intvec helper functions
Patch series "ipc: Clamp msgmni and shmmni to the real IPC_MNI limit".
The sysctl parameters msgmni and shmmni have an inherent limit of IPC_MNI
(32k). However, users may not be aware of that because they can write a
value much higher than that without getting any error or notification.
Reading the parameters back will show the newly written values which are
not real.
Enforcing the limit by failing sysctl parameter write, however, can break
existing user applications. To address this dilemma, the following new
sysctl range clamping APIs are added:
- proc_dointvec_clamp_minmax()
- proc_douintvec_clamp_minmax()
This new set of APIs is then used to set the real limit for msgmni and
shmmni without breaking existing applications. If any out of range value
is written to those sysctl parameters, the following warning will be
printed instead.
Kernel parameter "shmmni" was set out of range [0, 32768], clamped to 32768.
Reading the values back will show 32768 instead of some fake values.
This patch (of 3):
The current intvec range helper functions will fail with error when users
try to assign an out-of-range value.
The following new non-failing range helper functions are now added:
- proc_dointvec_clamp_minmax()
- proc_douintvec_clamp_minmax()
The new helper functions will clamp the value to within the given
min/max range without failing it.
Link: http://lkml.kernel.org/r/1519059231-2456-2-git-send-email-longman@xxxxxxxxxx
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/sysctl.h | 6 ++
kernel/sysctl.c | 97 ++++++++++++++++++++++++++++++++++++---
2 files changed, 96 insertions(+), 7 deletions(-)
diff -puN include/linux/sysctl.h~sysctl-add-range-clamping-intvec-helper-functions include/linux/sysctl.h
--- a/include/linux/sysctl.h~sysctl-add-range-clamping-intvec-helper-functions
+++ a/include/linux/sysctl.h
@@ -63,6 +63,12 @@ extern int proc_doulongvec_ms_jiffies_mi
void __user *, size_t *, loff_t *);
extern int proc_do_large_bitmap(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
+extern int proc_dointvec_clamp_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos);
+extern int proc_douintvec_clamp_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos);
/*
* Register a set of sysctl names by calling register_sysctl_table
diff -puN kernel/sysctl.c~sysctl-add-range-clamping-intvec-helper-functions kernel/sysctl.c
--- a/kernel/sysctl.c~sysctl-add-range-clamping-intvec-helper-functions
+++ a/kernel/sysctl.c
@@ -2500,9 +2500,15 @@ static int proc_dointvec_minmax_sysadmin
}
#endif
+/*
+ * The clamping flag, if set, will clamp the input value to the range
+ * specified by the given min/max values instead of returning error when
+ * out of range.
+ */
struct do_proc_dointvec_minmax_conv_param {
int *min;
int *max;
+ bool clamp;
};
static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
@@ -2512,9 +2518,18 @@ static int do_proc_dointvec_minmax_conv(
struct do_proc_dointvec_minmax_conv_param *param = data;
if (write) {
int val = *negp ? -*lvalp : *lvalp;
- if ((param->min && *param->min > val) ||
- (param->max && *param->max < val))
- return -EINVAL;
+ if (param->min && *param->min > val) {
+ if (param->clamp)
+ val = *param->min;
+ else
+ return -EINVAL;
+ }
+ if (param->max && *param->max < val) {
+ if (param->clamp)
+ val = *param->max;
+ else
+ return -EINVAL;
+ }
*valp = val;
} else {
int val = *valp;
@@ -2556,9 +2571,38 @@ int proc_dointvec_minmax(struct ctl_tabl
do_proc_dointvec_minmax_conv, ¶m);
}
+/**
+ * proc_dointvec_clamp_minmax - read a vector of integers with min/max values
+ * @table: the sysctl table
+ * @write: %TRUE if this is a write to the sysctl file
+ * @buffer: the user buffer
+ * @lenp: the size of the user buffer
+ * @ppos: file position
+ *
+ * Reads/writes up to table->maxlen/sizeof(unsigned int) integer
+ * values from/to the user buffer, treated as an ASCII string.
+ *
+ * This routine will clamp the values to within the range specified by
+ * table->extra1 (min) and table->extra2 (max).
+ *
+ * Returns 0 on success.
+ */
+int proc_dointvec_clamp_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct do_proc_dointvec_minmax_conv_param param = {
+ .min = (int *) table->extra1,
+ .max = (int *) table->extra2,
+ .clamp = true,
+ };
+ return do_proc_dointvec(table, write, buffer, lenp, ppos,
+ do_proc_dointvec_minmax_conv, ¶m);
+}
+
struct do_proc_douintvec_minmax_conv_param {
unsigned int *min;
unsigned int *max;
+ bool clamp;
};
static int do_proc_douintvec_minmax_conv(unsigned long *lvalp,
@@ -2573,10 +2617,18 @@ static int do_proc_douintvec_minmax_conv
if (*lvalp > UINT_MAX)
return -EINVAL;
- if ((param->min && *param->min > val) ||
- (param->max && *param->max < val))
- return -ERANGE;
-
+ if (param->min && *param->min > val) {
+ if (param->clamp)
+ val = *param->min;
+ else
+ return -ERANGE;
+ }
+ if (param->max && *param->max < val) {
+ if (param->clamp)
+ val = *param->max;
+ else
+ return -ERANGE;
+ }
*valp = val;
} else {
unsigned int val = *valp;
@@ -2614,6 +2666,37 @@ int proc_douintvec_minmax(struct ctl_tab
};
return do_proc_douintvec(table, write, buffer, lenp, ppos,
do_proc_douintvec_minmax_conv, ¶m);
+}
+
+/**
+ * proc_douintvec_clamp_minmax - read a vector of uints with min/max values
+ * @table: the sysctl table
+ * @write: %TRUE if this is a write to the sysctl file
+ * @buffer: the user buffer
+ * @lenp: the size of the user buffer
+ * @ppos: file position
+ *
+ * Reads/writes up to table->maxlen/sizeof(unsigned int) unsigned integer
+ * values from/to the user buffer, treated as an ASCII string. Negative
+ * strings are not allowed.
+ *
+ * This routine will clamp the values to within the range specified by
+ * table->extra1 (min) and table->extra2 (max). There is a final sanity
+ * check for UINT_MAX to avoid having to support wrap around uses from
+ * userspace.
+ *
+ * Returns 0 on success.
+ */
+int proc_douintvec_clamp_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct do_proc_douintvec_minmax_conv_param param = {
+ .min = (unsigned int *) table->extra1,
+ .max = (unsigned int *) table->extra2,
+ .clamp = true,
+ };
+ return do_proc_douintvec(table, write, buffer, lenp, ppos,
+ do_proc_douintvec_minmax_conv, ¶m);
}
static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
_
Patches currently in -mm which might be from longman@xxxxxxxxxx are
list_lru-prefetch-neighboring-list-entries-before-acquiring-lock.patch
sysctl-add-range-clamping-intvec-helper-functions.patch
sysctl-warn-when-a-clamped-sysctl-parameter-is-set-out-of-range.patch
ipc-clamp-msgmni-and-shmmni-to-the-real-ipc_mni-limit.patch
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