On 05/07/2018 06:39 PM, Luis R. Rodriguez wrote:
> On Mon, May 07, 2018 at 04:59:09PM -0400, Waiman Long wrote:
>> 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.
>>
>> The right limits are now set for msgmni and shmmni so that the users
>> will become aware if they set a value outside of the acceptable range.
>>
>> Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
>> ---
>> ipc/ipc_sysctl.c | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
>> index 8ad93c2..f87cb29 100644
>> --- a/ipc/ipc_sysctl.c
>> +++ b/ipc/ipc_sysctl.c
>> @@ -99,6 +99,7 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table, int write,
>> 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 +121,9 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table, int write,
>> .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,
>> },
>> {
>> .procname = "shm_rmid_forced",
>> @@ -147,7 +150,7 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table, int write,
>> .mode = 0644,
>> .proc_handler = proc_ipc_dointvec_minmax,
>> .extra1 = &zero,
>> - .extra2 = &int_max,
>> + .extra2 = &ipc_mni,
>> },
>> {
>> .procname = "auto_msgmni",
>> --
>> 1.8.3.1
> It seems negative values are not allowed, if true then having
> a caller to use proc_douintvec_minmax() would help with ensuring
> no invalid negative input values are used as well.
>
> Luis
Negative value doesn't mean sense here. So it is true that we can use
proc_douintvec_minmax() instead. However, the data types themselves are
defined as "int". So I think it is better to keep using
proc_dointvec_minmax() to be consistent with the data type.
Cheers,
Longman
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