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compat_ioctl: handle PPPIOCGIDLE for 64-bit time_t

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The ppp_idle structure is defined in terms of __kernel_time_t, which is
defined as 'long' on all architectures, and this usage is not affected
by the y2038 problem since it transports a time interval rather than an
absolute time.

However, the ppp user space defines the same structure as time_t, which
may be 64-bit wide on new libc versions even on 32-bit architectures.

It's easy enough to just handle both possible structure layouts on
all architectures, to deal with the possibility that a user space ppp
implementation comes with its own ppp_idle structure definition, as well
as to document the fact that the driver is y2038-safe.

Doing this also avoids the need for a special compat mode translation,
since 32-bit and 64-bit kernels now support the same interfaces.  The old
32-bit structure is also available on native 64-bit architectures now,
but this is harmless.

Cc: netdev@vger.kernel.org
Cc: linux-ppp@vger.kernel.org
Cc: Paul Mackerras <paulus@samba.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Arnd Bergmann
2019-04-16 22:19:44 +02:00
parent 5b6c02df50
commit 17c7e7f407
5 changed files with 37 additions and 38 deletions
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19
drivers/net/ppp/ppp_generic.c
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@@ -612,7 +612,8 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
struct ppp_file *pf;
struct ppp *ppp;
int err = -EFAULT, val, val2, i;
struct ppp_idle idle;
struct ppp_idle32 idle32;
struct ppp_idle64 idle64;
struct npioctl npi;
int unit, cflags;
struct slcompress *vj;
@@ -735,10 +736,18 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
err = 0;
break;
case PPPIOCGIDLE:
idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
if (copy_to_user(argp, &idle, sizeof(idle)))
case PPPIOCGIDLE32:
idle32.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
idle32.recv_idle = (jiffies - ppp->last_recv) / HZ;
if (copy_to_user(argp, &idle32, sizeof(idle32)))
break;
err = 0;
break;
case PPPIOCGIDLE64:
idle64.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
idle64.recv_idle = (jiffies - ppp->last_recv) / HZ;
if (copy_to_user(argp, &idle64, sizeof(idle64)))
break;
err = 0;
break;