mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
376 lines
9.6 KiB
376 lines
9.6 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
|
|
|
#include <linux/compat.h> |
|
#include <linux/syscalls.h> |
|
#include <linux/time_namespace.h> |
|
|
|
#include "futex.h" |
|
|
|
/* |
|
* Support for robust futexes: the kernel cleans up held futexes at |
|
* thread exit time. |
|
* |
|
* Implementation: user-space maintains a per-thread list of locks it |
|
* is holding. Upon do_exit(), the kernel carefully walks this list, |
|
* and marks all locks that are owned by this thread with the |
|
* FUTEX_OWNER_DIED bit, and wakes up a waiter (if any). The list is |
|
* always manipulated with the lock held, so the list is private and |
|
* per-thread. Userspace also maintains a per-thread 'list_op_pending' |
|
* field, to allow the kernel to clean up if the thread dies after |
|
* acquiring the lock, but just before it could have added itself to |
|
* the list. There can only be one such pending lock. |
|
*/ |
|
|
|
/** |
|
* sys_set_robust_list() - Set the robust-futex list head of a task |
|
* @head: pointer to the list-head |
|
* @len: length of the list-head, as userspace expects |
|
*/ |
|
SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head, |
|
size_t, len) |
|
{ |
|
/* |
|
* The kernel knows only one size for now: |
|
*/ |
|
if (unlikely(len != sizeof(*head))) |
|
return -EINVAL; |
|
|
|
current->robust_list = head; |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* sys_get_robust_list() - Get the robust-futex list head of a task |
|
* @pid: pid of the process [zero for current task] |
|
* @head_ptr: pointer to a list-head pointer, the kernel fills it in |
|
* @len_ptr: pointer to a length field, the kernel fills in the header size |
|
*/ |
|
SYSCALL_DEFINE3(get_robust_list, int, pid, |
|
struct robust_list_head __user * __user *, head_ptr, |
|
size_t __user *, len_ptr) |
|
{ |
|
struct robust_list_head __user *head; |
|
unsigned long ret; |
|
struct task_struct *p; |
|
|
|
rcu_read_lock(); |
|
|
|
ret = -ESRCH; |
|
if (!pid) |
|
p = current; |
|
else { |
|
p = find_task_by_vpid(pid); |
|
if (!p) |
|
goto err_unlock; |
|
} |
|
|
|
ret = -EPERM; |
|
if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS)) |
|
goto err_unlock; |
|
|
|
head = p->robust_list; |
|
rcu_read_unlock(); |
|
|
|
if (put_user(sizeof(*head), len_ptr)) |
|
return -EFAULT; |
|
return put_user(head, head_ptr); |
|
|
|
err_unlock: |
|
rcu_read_unlock(); |
|
|
|
return ret; |
|
} |
|
|
|
long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, |
|
u32 __user *uaddr2, u32 val2, u32 val3) |
|
{ |
|
int cmd = op & FUTEX_CMD_MASK; |
|
unsigned int flags = 0; |
|
|
|
if (!(op & FUTEX_PRIVATE_FLAG)) |
|
flags |= FLAGS_SHARED; |
|
|
|
if (op & FUTEX_CLOCK_REALTIME) { |
|
flags |= FLAGS_CLOCKRT; |
|
if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI && |
|
cmd != FUTEX_LOCK_PI2) |
|
return -ENOSYS; |
|
} |
|
|
|
switch (cmd) { |
|
case FUTEX_WAIT: |
|
val3 = FUTEX_BITSET_MATCH_ANY; |
|
fallthrough; |
|
case FUTEX_WAIT_BITSET: |
|
return futex_wait(uaddr, flags, val, timeout, val3); |
|
case FUTEX_WAKE: |
|
val3 = FUTEX_BITSET_MATCH_ANY; |
|
fallthrough; |
|
case FUTEX_WAKE_BITSET: |
|
return futex_wake(uaddr, flags, val, val3); |
|
case FUTEX_REQUEUE: |
|
return futex_requeue(uaddr, flags, uaddr2, val, val2, NULL, 0); |
|
case FUTEX_CMP_REQUEUE: |
|
return futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 0); |
|
case FUTEX_WAKE_OP: |
|
return futex_wake_op(uaddr, flags, uaddr2, val, val2, val3); |
|
case FUTEX_LOCK_PI: |
|
flags |= FLAGS_CLOCKRT; |
|
fallthrough; |
|
case FUTEX_LOCK_PI2: |
|
return futex_lock_pi(uaddr, flags, timeout, 0); |
|
case FUTEX_UNLOCK_PI: |
|
return futex_unlock_pi(uaddr, flags); |
|
case FUTEX_TRYLOCK_PI: |
|
return futex_lock_pi(uaddr, flags, NULL, 1); |
|
case FUTEX_WAIT_REQUEUE_PI: |
|
val3 = FUTEX_BITSET_MATCH_ANY; |
|
return futex_wait_requeue_pi(uaddr, flags, val, timeout, val3, |
|
uaddr2); |
|
case FUTEX_CMP_REQUEUE_PI: |
|
return futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 1); |
|
} |
|
return -ENOSYS; |
|
} |
|
|
|
static __always_inline bool futex_cmd_has_timeout(u32 cmd) |
|
{ |
|
switch (cmd) { |
|
case FUTEX_WAIT: |
|
case FUTEX_LOCK_PI: |
|
case FUTEX_LOCK_PI2: |
|
case FUTEX_WAIT_BITSET: |
|
case FUTEX_WAIT_REQUEUE_PI: |
|
return true; |
|
} |
|
return false; |
|
} |
|
|
|
static __always_inline int |
|
futex_init_timeout(u32 cmd, u32 op, struct timespec64 *ts, ktime_t *t) |
|
{ |
|
if (!timespec64_valid(ts)) |
|
return -EINVAL; |
|
|
|
*t = timespec64_to_ktime(*ts); |
|
if (cmd == FUTEX_WAIT) |
|
*t = ktime_add_safe(ktime_get(), *t); |
|
else if (cmd != FUTEX_LOCK_PI && !(op & FUTEX_CLOCK_REALTIME)) |
|
*t = timens_ktime_to_host(CLOCK_MONOTONIC, *t); |
|
return 0; |
|
} |
|
|
|
SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, |
|
const struct __kernel_timespec __user *, utime, |
|
u32 __user *, uaddr2, u32, val3) |
|
{ |
|
int ret, cmd = op & FUTEX_CMD_MASK; |
|
ktime_t t, *tp = NULL; |
|
struct timespec64 ts; |
|
|
|
if (utime && futex_cmd_has_timeout(cmd)) { |
|
if (unlikely(should_fail_futex(!(op & FUTEX_PRIVATE_FLAG)))) |
|
return -EFAULT; |
|
if (get_timespec64(&ts, utime)) |
|
return -EFAULT; |
|
ret = futex_init_timeout(cmd, op, &ts, &t); |
|
if (ret) |
|
return ret; |
|
tp = &t; |
|
} |
|
|
|
return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3); |
|
} |
|
|
|
/* Mask of available flags for each futex in futex_waitv list */ |
|
#define FUTEXV_WAITER_MASK (FUTEX_32 | FUTEX_PRIVATE_FLAG) |
|
|
|
/** |
|
* futex_parse_waitv - Parse a waitv array from userspace |
|
* @futexv: Kernel side list of waiters to be filled |
|
* @uwaitv: Userspace list to be parsed |
|
* @nr_futexes: Length of futexv |
|
* |
|
* Return: Error code on failure, 0 on success |
|
*/ |
|
static int futex_parse_waitv(struct futex_vector *futexv, |
|
struct futex_waitv __user *uwaitv, |
|
unsigned int nr_futexes) |
|
{ |
|
struct futex_waitv aux; |
|
unsigned int i; |
|
|
|
for (i = 0; i < nr_futexes; i++) { |
|
if (copy_from_user(&aux, &uwaitv[i], sizeof(aux))) |
|
return -EFAULT; |
|
|
|
if ((aux.flags & ~FUTEXV_WAITER_MASK) || aux.__reserved) |
|
return -EINVAL; |
|
|
|
if (!(aux.flags & FUTEX_32)) |
|
return -EINVAL; |
|
|
|
futexv[i].w.flags = aux.flags; |
|
futexv[i].w.val = aux.val; |
|
futexv[i].w.uaddr = aux.uaddr; |
|
futexv[i].q = futex_q_init; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* sys_futex_waitv - Wait on a list of futexes |
|
* @waiters: List of futexes to wait on |
|
* @nr_futexes: Length of futexv |
|
* @flags: Flag for timeout (monotonic/realtime) |
|
* @timeout: Optional absolute timeout. |
|
* @clockid: Clock to be used for the timeout, realtime or monotonic. |
|
* |
|
* Given an array of `struct futex_waitv`, wait on each uaddr. The thread wakes |
|
* if a futex_wake() is performed at any uaddr. The syscall returns immediately |
|
* if any waiter has *uaddr != val. *timeout is an optional timeout value for |
|
* the operation. Each waiter has individual flags. The `flags` argument for |
|
* the syscall should be used solely for specifying the timeout as realtime, if |
|
* needed. Flags for private futexes, sizes, etc. should be used on the |
|
* individual flags of each waiter. |
|
* |
|
* Returns the array index of one of the woken futexes. No further information |
|
* is provided: any number of other futexes may also have been woken by the |
|
* same event, and if more than one futex was woken, the retrned index may |
|
* refer to any one of them. (It is not necessaryily the futex with the |
|
* smallest index, nor the one most recently woken, nor...) |
|
*/ |
|
|
|
SYSCALL_DEFINE5(futex_waitv, struct futex_waitv __user *, waiters, |
|
unsigned int, nr_futexes, unsigned int, flags, |
|
struct __kernel_timespec __user *, timeout, clockid_t, clockid) |
|
{ |
|
struct hrtimer_sleeper to; |
|
struct futex_vector *futexv; |
|
struct timespec64 ts; |
|
ktime_t time; |
|
int ret; |
|
|
|
/* This syscall supports no flags for now */ |
|
if (flags) |
|
return -EINVAL; |
|
|
|
if (!nr_futexes || nr_futexes > FUTEX_WAITV_MAX || !waiters) |
|
return -EINVAL; |
|
|
|
if (timeout) { |
|
int flag_clkid = 0, flag_init = 0; |
|
|
|
if (clockid == CLOCK_REALTIME) { |
|
flag_clkid = FLAGS_CLOCKRT; |
|
flag_init = FUTEX_CLOCK_REALTIME; |
|
} |
|
|
|
if (clockid != CLOCK_REALTIME && clockid != CLOCK_MONOTONIC) |
|
return -EINVAL; |
|
|
|
if (get_timespec64(&ts, timeout)) |
|
return -EFAULT; |
|
|
|
/* |
|
* Since there's no opcode for futex_waitv, use |
|
* FUTEX_WAIT_BITSET that uses absolute timeout as well |
|
*/ |
|
ret = futex_init_timeout(FUTEX_WAIT_BITSET, flag_init, &ts, &time); |
|
if (ret) |
|
return ret; |
|
|
|
futex_setup_timer(&time, &to, flag_clkid, 0); |
|
} |
|
|
|
futexv = kcalloc(nr_futexes, sizeof(*futexv), GFP_KERNEL); |
|
if (!futexv) |
|
return -ENOMEM; |
|
|
|
ret = futex_parse_waitv(futexv, waiters, nr_futexes); |
|
if (!ret) |
|
ret = futex_wait_multiple(futexv, nr_futexes, timeout ? &to : NULL); |
|
|
|
if (timeout) { |
|
hrtimer_cancel(&to.timer); |
|
destroy_hrtimer_on_stack(&to.timer); |
|
} |
|
|
|
kfree(futexv); |
|
return ret; |
|
} |
|
|
|
#ifdef CONFIG_COMPAT |
|
COMPAT_SYSCALL_DEFINE2(set_robust_list, |
|
struct compat_robust_list_head __user *, head, |
|
compat_size_t, len) |
|
{ |
|
if (unlikely(len != sizeof(*head))) |
|
return -EINVAL; |
|
|
|
current->compat_robust_list = head; |
|
|
|
return 0; |
|
} |
|
|
|
COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid, |
|
compat_uptr_t __user *, head_ptr, |
|
compat_size_t __user *, len_ptr) |
|
{ |
|
struct compat_robust_list_head __user *head; |
|
unsigned long ret; |
|
struct task_struct *p; |
|
|
|
rcu_read_lock(); |
|
|
|
ret = -ESRCH; |
|
if (!pid) |
|
p = current; |
|
else { |
|
p = find_task_by_vpid(pid); |
|
if (!p) |
|
goto err_unlock; |
|
} |
|
|
|
ret = -EPERM; |
|
if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS)) |
|
goto err_unlock; |
|
|
|
head = p->compat_robust_list; |
|
rcu_read_unlock(); |
|
|
|
if (put_user(sizeof(*head), len_ptr)) |
|
return -EFAULT; |
|
return put_user(ptr_to_compat(head), head_ptr); |
|
|
|
err_unlock: |
|
rcu_read_unlock(); |
|
|
|
return ret; |
|
} |
|
#endif /* CONFIG_COMPAT */ |
|
|
|
#ifdef CONFIG_COMPAT_32BIT_TIME |
|
SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val, |
|
const struct old_timespec32 __user *, utime, u32 __user *, uaddr2, |
|
u32, val3) |
|
{ |
|
int ret, cmd = op & FUTEX_CMD_MASK; |
|
ktime_t t, *tp = NULL; |
|
struct timespec64 ts; |
|
|
|
if (utime && futex_cmd_has_timeout(cmd)) { |
|
if (get_old_timespec32(&ts, utime)) |
|
return -EFAULT; |
|
ret = futex_init_timeout(cmd, op, &ts, &t); |
|
if (ret) |
|
return ret; |
|
tp = &t; |
|
} |
|
|
|
return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3); |
|
} |
|
#endif /* CONFIG_COMPAT_32BIT_TIME */ |
|
|
|
|