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Message-ID: <20110919173905.GA3804@albatros> Date: Mon, 19 Sep 2011 21:39:05 +0400 From: Vasiliy Kulikov <segoon@...nwall.com> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Balbir Singh <bsingharora@...il.com>, Shailabh Nagar <nagar@...ibm.com>, linux-kernel@...r.kernel.org, security@...nel.org, Eric Paris <eparis@...hat.com>, Stephen Wilson <wilsons@...rt.ca>, KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>, David Rientjes <rientjes@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>, Balbir Singh <balbir@...ux.vnet.ibm.com>, kernel-hardening@...ts.openwall.com Subject: Re: [Security] [PATCH 2/2] taskstats: restrict access to user On Mon, Sep 19, 2011 at 09:40 -0700, Linus Torvalds wrote: > diff --git a/kernel/taskstats.c b/kernel/taskstats.c > index e19ce1454ee1..5874d4866b3c 100644 > --- a/kernel/taskstats.c > +++ b/kernel/taskstats.c > @@ -457,6 +457,8 @@ static int cmd_attr_register_cpumask(struct genl_info *info) > cpumask_var_t mask; > int rc; > > + if (!capable(CAP_SYS_ADMIN)) > + return -EPERM; Shouldn't it simply protect taskstats_user_cmd()? You may still poll the counters with TASKSTATS_CMD_ATTR_PID/TASKSTATS_CMD_ATTR_TGID. Or ptrace_may_access() in taskstats_user_cmd(). > if (!alloc_cpumask_var(&mask, GFP_KERNEL)) > return -ENOMEM; > rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask); > diff --git a/kernel/tsacct.c b/kernel/tsacct.c > index 24dc60d9fa1f..110ca5a03bd6 100644 > --- a/kernel/tsacct.c > +++ b/kernel/tsacct.c > @@ -78,6 +78,7 @@ void bacct_add_tsk(struct taskstats *stats, struct task_struct *tsk) > > #define KB 1024 > #define MB (1024*KB) > +#define KB_MASK (~(KB-1)) > /* > * fill in extended accounting fields > */ > @@ -100,9 +101,9 @@ void xacct_add_tsk(struct taskstats *stats, struct task_struct *p) > stats->read_syscalls = p->ioac.syscr; > stats->write_syscalls = p->ioac.syscw; > #ifdef CONFIG_TASK_IO_ACCOUNTING > - stats->read_bytes = p->ioac.read_bytes; > - stats->write_bytes = p->ioac.write_bytes; > - stats->cancelled_write_bytes = p->ioac.cancelled_write_bytes; > + stats->read_bytes = p->ioac.read_bytes & KB_MASK; > + stats->write_bytes = p->ioac.write_bytes & KB_MASK; > + stats->cancelled_write_bytes = p->ioac.cancelled_write_bytes & KB_MASK; > #else > stats->read_bytes = 0; > stats->write_bytes = 0; -- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments
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