The patch titled
Subject: ipc/ipc_sysctl.c: clamp msgmni and shmmni to the real IPCMNI limit
has been added to the -mm tree. Its filename is
ipc-clamp-msgmni-and-shmmni-to-the-real-ipcmni-limit.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-clamp-msgmni-and-shmmni-to-the-real-ipcmni-limit.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-clamp-msgmni-and-shmmni-to-the-real-ipcmni-limit.patch
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From: Waiman Long <longman@xxxxxxxxxx>
Subject: ipc/ipc_sysctl.c: clamp msgmni and shmmni to the real IPCMNI limit
A user can write arbitrary integer values to msgmni and shmmni sysctl
parameters without getting error, but the actual limit is really IPCMNI
(32k). This can mislead users as they think they can get a value that is
not real.
Enforcing the limit by failing the sysctl parameter write, however, can
break existing user applications. Instead, the range clamping flag is set
to enforce the limit without failing existing user code. Users can easily
figure out if the sysctl parameter value is out of range by either reading
back the parameter value or checking the kernel ring buffer for warning.
Link: http://lkml.kernel.org/r/1519926220-7453-6-git-send-email-longman@xxxxxxxxxx
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/ipc_sysctl.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff -puN ipc/ipc_sysctl.c~ipc-clamp-msgmni-and-shmmni-to-the-real-ipcmni-limit ipc/ipc_sysctl.c
--- a/ipc/ipc_sysctl.c~ipc-clamp-msgmni-and-shmmni-to-the-real-ipcmni-limit
+++ a/ipc/ipc_sysctl.c
@@ -41,12 +41,21 @@ static int proc_ipc_dointvec(struct ctl_
static int proc_ipc_dointvec_minmax(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
+ int ret;
struct ctl_table ipc_table;
memcpy(&ipc_table, table, sizeof(ipc_table));
ipc_table.data = get_ipc(table);
- return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
+ ret = proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
+
+ /*
+ * Copy back the CTL_FLAGS_OOR_WARNED flag which may be set in
+ * the temporary ctl_table entry.
+ */
+ table->flags |= (ipc_table.flags & CTL_FLAGS_OOR_WARNED);
+
+ return ret;
}
static int proc_ipc_dointvec_minmax_orphans(struct ctl_table *table, int write,
@@ -99,6 +108,7 @@ static int proc_ipc_auto_msgmni(struct c
static int zero;
static int one = 1;
static int int_max = INT_MAX;
+static int ipc_mni = IPCMNI;
static struct ctl_table ipc_kern_table[] = {
{
@@ -120,7 +130,10 @@ static struct ctl_table ipc_kern_table[]
.data = &init_ipc_ns.shm_ctlmni,
.maxlen = sizeof(init_ipc_ns.shm_ctlmni),
.mode = 0644,
- .proc_handler = proc_ipc_dointvec,
+ .proc_handler = proc_ipc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &ipc_mni,
+ .flags = CTL_FLAGS_CLAMP_RANGE,
},
{
.procname = "shm_rmid_forced",
@@ -147,7 +160,8 @@ static struct ctl_table ipc_kern_table[]
.mode = 0644,
.proc_handler = proc_ipc_dointvec_minmax,
.extra1 = &zero,
- .extra2 = &int_max,
+ .extra2 = &ipc_mni,
+ .flags = CTL_FLAGS_CLAMP_RANGE,
},
{
.procname = "auto_msgmni",
_
Patches currently in -mm which might be from longman@xxxxxxxxxx are
list_lru-prefetch-neighboring-list-entries-before-acquiring-lock.patch
proc-sysctl-fix-typo-in-sysctl_check_table_array.patch
sysctl-add-kdoc-comments-to-do_proc_douintvec_minmax_conv_param.patch
sysctl-add-flags-to-support-min-max-range-clamping.patch
sysctl-warn-when-a-clamped-sysctl-parameter-is-set-out-of-range.patch
ipc-clamp-msgmni-and-shmmni-to-the-real-ipcmni-limit.patch
ipc-clamp-semmni-to-the-real-ipcmni-limit.patch
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