diff options
| -rw-r--r-- | kernel/time/posix-cpu-timers.c | 65 |
1 files changed, 44 insertions, 21 deletions
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 387e0e86e1b8..b06ed8b14861 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -35,27 +35,52 @@ void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new) spin_unlock_irq(&task->sighand->siglock); } -static int check_clock(const clockid_t which_clock) +/* + * Functions for validating access to tasks. + */ +static struct task_struct *lookup_task(const pid_t pid, bool thread) { - int error = 0; struct task_struct *p; - const pid_t pid = CPUCLOCK_PID(which_clock); - if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX) - return -EINVAL; + if (!pid) + return thread ? current : current->group_leader; + + p = find_task_by_vpid(pid); + if (!p || p == current) + return p; + if (thread) + return same_thread_group(p, current) ? p : NULL; + if (p == current) + return p; + return has_group_leader_pid(p) ? p : NULL; +} + +static struct task_struct *__get_task_for_clock(const clockid_t clock, + bool getref) +{ + const bool thread = !!CPUCLOCK_PERTHREAD(clock); + const pid_t pid = CPUCLOCK_PID(clock); + struct task_struct *p; - if (pid == 0) - return 0; + if (CPUCLOCK_WHICH(clock) >= CPUCLOCK_MAX) + return NULL; rcu_read_lock(); - p = find_task_by_vpid(pid); - if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ? - same_thread_group(p, current) : has_group_leader_pid(p))) { - error = -EINVAL; - } + p = lookup_task(pid, thread); + if (p && getref) + get_task_struct(p); rcu_read_unlock(); + return p; +} - return error; +static inline struct task_struct *get_task_for_clock(const clockid_t clock) +{ + return __get_task_for_clock(clock, true); +} + +static inline int validate_clock_permissions(const clockid_t clock) +{ + return __get_task_for_clock(clock, false) ? 0 : -EINVAL; } /* @@ -125,7 +150,8 @@ static inline u64 virt_ticks(struct task_struct *p) static int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp) { - int error = check_clock(which_clock); + int error = validate_clock_permissions(which_clock); + if (!error) { tp->tv_sec = 0; tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ); @@ -142,20 +168,17 @@ posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp) } static int -posix_cpu_clock_set(const clockid_t which_clock, const struct timespec64 *tp) +posix_cpu_clock_set(const clockid_t clock, const struct timespec64 *tp) { + int error = validate_clock_permissions(clock); + /* * You can never reset a CPU clock, but we check for other errors * in the call before failing with EPERM. */ - int error = check_clock(which_clock); - if (error == 0) { - error = -EPERM; - } - return error; + return error ? : -EPERM; } - /* * Sample a per-thread clock for the given task. */ |