do_sigaltstack(): lift copying to/from userland into callers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>zero-colors
Al Viro
parent
613763a1f0
commit
bcfe8ad8ef
107
kernel/signal.c
107
kernel/signal.c
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@ -3113,78 +3113,68 @@ int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
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}
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static int
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do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
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do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
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{
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stack_t oss;
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int error;
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struct task_struct *t = current;
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oss.ss_sp = (void __user *) current->sas_ss_sp;
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oss.ss_size = current->sas_ss_size;
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oss.ss_flags = sas_ss_flags(sp) |
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(current->sas_ss_flags & SS_FLAG_BITS);
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if (oss) {
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memset(oss, 0, sizeof(stack_t));
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oss->ss_sp = (void __user *) t->sas_ss_sp;
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oss->ss_size = t->sas_ss_size;
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oss->ss_flags = sas_ss_flags(sp) |
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(current->sas_ss_flags & SS_FLAG_BITS);
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}
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if (uss) {
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void __user *ss_sp;
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size_t ss_size;
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unsigned ss_flags;
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if (ss) {
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void __user *ss_sp = ss->ss_sp;
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size_t ss_size = ss->ss_size;
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unsigned ss_flags = ss->ss_flags;
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int ss_mode;
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error = -EFAULT;
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if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
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goto out;
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error = __get_user(ss_sp, &uss->ss_sp) |
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__get_user(ss_flags, &uss->ss_flags) |
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__get_user(ss_size, &uss->ss_size);
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if (error)
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goto out;
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error = -EPERM;
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if (on_sig_stack(sp))
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goto out;
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if (unlikely(on_sig_stack(sp)))
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return -EPERM;
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ss_mode = ss_flags & ~SS_FLAG_BITS;
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error = -EINVAL;
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if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
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ss_mode != 0)
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goto out;
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if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
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ss_mode != 0))
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return -EINVAL;
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if (ss_mode == SS_DISABLE) {
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ss_size = 0;
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ss_sp = NULL;
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} else {
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error = -ENOMEM;
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if (ss_size < MINSIGSTKSZ)
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goto out;
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if (unlikely(ss_size < MINSIGSTKSZ))
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return -ENOMEM;
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}
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current->sas_ss_sp = (unsigned long) ss_sp;
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current->sas_ss_size = ss_size;
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current->sas_ss_flags = ss_flags;
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t->sas_ss_sp = (unsigned long) ss_sp;
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t->sas_ss_size = ss_size;
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t->sas_ss_flags = ss_flags;
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}
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error = 0;
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if (uoss) {
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error = -EFAULT;
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if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
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goto out;
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error = __put_user(oss.ss_sp, &uoss->ss_sp) |
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__put_user(oss.ss_size, &uoss->ss_size) |
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__put_user(oss.ss_flags, &uoss->ss_flags);
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}
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out:
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return error;
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return 0;
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}
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SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
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{
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return do_sigaltstack(uss, uoss, current_user_stack_pointer());
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stack_t new, old;
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int err;
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if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
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return -EFAULT;
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err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
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current_user_stack_pointer());
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if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
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err = -EFAULT;
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return err;
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}
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int restore_altstack(const stack_t __user *uss)
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{
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int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
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stack_t new;
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if (copy_from_user(&new, uss, sizeof(stack_t)))
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return -EFAULT;
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(void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
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/* squash all but EFAULT for now */
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return err == -EFAULT ? err : 0;
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return 0;
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}
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int __save_altstack(stack_t __user *uss, unsigned long sp)
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@ -3207,29 +3197,24 @@ COMPAT_SYSCALL_DEFINE2(sigaltstack,
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{
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stack_t uss, uoss;
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int ret;
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mm_segment_t seg;
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if (uss_ptr) {
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compat_stack_t uss32;
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memset(&uss, 0, sizeof(stack_t));
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if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
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return -EFAULT;
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uss.ss_sp = compat_ptr(uss32.ss_sp);
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uss.ss_flags = uss32.ss_flags;
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uss.ss_size = uss32.ss_size;
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}
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seg = get_fs();
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set_fs(KERNEL_DS);
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ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
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(stack_t __force __user *) &uoss,
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ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
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compat_user_stack_pointer());
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set_fs(seg);
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if (ret >= 0 && uoss_ptr) {
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if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
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__put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
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__put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
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__put_user(uoss.ss_size, &uoss_ptr->ss_size))
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compat_stack_t old;
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memset(&old, 0, sizeof(old));
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old.ss_sp = ptr_to_compat(uoss.ss_sp);
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old.ss_flags = uoss.ss_flags;
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old.ss_size = uoss.ss_size;
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if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
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ret = -EFAULT;
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}
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return ret;
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