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Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/posix-cpu-timers.c44
1 files changed, 35 insertions, 9 deletions
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index c3a95b122209..92a431981b1c 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -47,25 +47,46 @@ void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
/*
* Functions for validating access to tasks.
*/
-static struct task_struct *lookup_task(const pid_t pid, bool thread)
+static struct task_struct *lookup_task(const pid_t pid, bool thread,
+ bool gettime)
{
struct task_struct *p;
+ /*
+ * If the encoded PID is 0, then the timer is targeted at current
+ * or the process to which current belongs.
+ */
if (!pid)
return thread ? current : current->group_leader;
p = find_task_by_vpid(pid);
- if (!p || p == current)
+ if (!p)
return p;
+
if (thread)
return same_thread_group(p, current) ? p : NULL;
- if (p == current)
- return p;
+
+ if (gettime) {
+ /*
+ * For clock_gettime(PROCESS) the task does not need to be
+ * the actual group leader. tsk->sighand gives
+ * access to the group's clock.
+ *
+ * Timers need the group leader because they take a
+ * reference on it and store the task pointer until the
+ * timer is destroyed.
+ */
+ return (p == current || thread_group_leader(p)) ? p : NULL;
+ }
+
+ /*
+ * For processes require that p is group leader.
+ */
return has_group_leader_pid(p) ? p : NULL;
}
static struct task_struct *__get_task_for_clock(const clockid_t clock,
- bool getref)
+ bool getref, bool gettime)
{
const bool thread = !!CPUCLOCK_PERTHREAD(clock);
const pid_t pid = CPUCLOCK_PID(clock);
@@ -75,7 +96,7 @@ static struct task_struct *__get_task_for_clock(const clockid_t clock,
return NULL;
rcu_read_lock();
- p = lookup_task(pid, thread);
+ p = lookup_task(pid, thread, gettime);
if (p && getref)
get_task_struct(p);
rcu_read_unlock();
@@ -84,12 +105,17 @@ static struct task_struct *__get_task_for_clock(const clockid_t clock,
static inline struct task_struct *get_task_for_clock(const clockid_t clock)
{
- return __get_task_for_clock(clock, true);
+ return __get_task_for_clock(clock, true, false);
+}
+
+static inline struct task_struct *get_task_for_clock_get(const clockid_t clock)
+{
+ return __get_task_for_clock(clock, true, true);
}
static inline int validate_clock_permissions(const clockid_t clock)
{
- return __get_task_for_clock(clock, false) ? 0 : -EINVAL;
+ return __get_task_for_clock(clock, false, false) ? 0 : -EINVAL;
}
/*
@@ -339,7 +365,7 @@ static int posix_cpu_clock_get(const clockid_t clock, struct timespec64 *tp)
struct task_struct *tsk;
u64 t;
- tsk = get_task_for_clock(clock);
+ tsk = get_task_for_clock_get(clock);
if (!tsk)
return -EINVAL;