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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

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Pull Yama locking fix from James Morris:
 "Fix for the Yama LSM"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  Yama: fix double-spinlock and user access in atomic context
This commit is contained in:
Linus Torvalds 2016-05-26 09:15:19 -07:00
commit 159d08f4b8
1 changed files with 63 additions and 6 deletions
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69
security/yama/yama_lsm.c
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@ -19,6 +19,9 @@
#include <linux/ratelimit.h>
#include <linux/workqueue.h>
#include <linux/string_helpers.h>
#include <linux/task_work.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#define YAMA_SCOPE_DISABLED 0
#define YAMA_SCOPE_RELATIONAL 1
@ -42,20 +45,71 @@ static DEFINE_SPINLOCK(ptracer_relations_lock);
static void yama_relation_cleanup(struct work_struct *work);
static DECLARE_WORK(yama_relation_work, yama_relation_cleanup);
static void report_access(const char *access, struct task_struct *target,
struct task_struct *agent)
struct access_report_info {
struct callback_head work;
const char *access;
struct task_struct *target;
struct task_struct *agent;
};
static void __report_access(struct callback_head *work)
{
struct access_report_info *info =
container_of(work, struct access_report_info, work);
char *target_cmd, *agent_cmd;
target_cmd = kstrdup_quotable_cmdline(target, GFP_ATOMIC);
agent_cmd = kstrdup_quotable_cmdline(agent, GFP_ATOMIC);
target_cmd = kstrdup_quotable_cmdline(info->target, GFP_KERNEL);
agent_cmd = kstrdup_quotable_cmdline(info->agent, GFP_KERNEL);
pr_notice_ratelimited(
"ptrace %s of \"%s\"[%d] was attempted by \"%s\"[%d]\n",
access, target_cmd, target->pid, agent_cmd, agent->pid);
info->access, target_cmd, info->target->pid, agent_cmd,
info->agent->pid);
kfree(agent_cmd);
kfree(target_cmd);
put_task_struct(info->agent);
put_task_struct(info->target);
kfree(info);
}
/* defers execution because cmdline access can sleep */
static void report_access(const char *access, struct task_struct *target,
struct task_struct *agent)
{
struct access_report_info *info;
char agent_comm[sizeof(agent->comm)];
assert_spin_locked(&target->alloc_lock); /* for target->comm */
if (current->flags & PF_KTHREAD) {
/* I don't think kthreads call task_work_run() before exiting.
* Imagine angry ranting about procfs here.
*/
pr_notice_ratelimited(
"ptrace %s of \"%s\"[%d] was attempted by \"%s\"[%d]\n",
access, target->comm, target->pid,
get_task_comm(agent_comm, agent), agent->pid);
return;
}
info = kmalloc(sizeof(*info), GFP_ATOMIC);
if (!info)
return;
init_task_work(&info->work, __report_access);
get_task_struct(target);
get_task_struct(agent);
info->access = access;
info->target = target;
info->agent = agent;
if (task_work_add(current, &info->work, true) == 0)
return; /* success */
WARN(1, "report_access called from exiting task");
put_task_struct(target);
put_task_struct(agent);
kfree(info);
}
/**
@ -351,8 +405,11 @@ int yama_ptrace_traceme(struct task_struct *parent)
break;
}
if (rc)
if (rc) {
task_lock(current);
report_access("traceme", current, parent);
task_unlock(current);
}
return rc;
}