/* * This contains the io-permission bitmap code - written by obz, with changes * by Linus. */ #include <linux/sched.h> #include <linux/kernel.h> #include <linux/capability.h> #include <linux/errno.h> #include <linux/types.h> #include <linux/ioport.h> #include <linux/smp.h> #include <linux/stddef.h> #include <linux/slab.h> #include <linux/thread_info.h> #include <linux/syscalls.h> /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */ static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value) { int i; if (new_value) for (i = base; i < base + extent; i++) __set_bit(i, bitmap); else for (i = base; i < base + extent; i++) clear_bit(i, bitmap); } /* * this changes the io permissions bitmap in the current task. */ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) { unsigned int i, max_long, bytes, bytes_updated; struct thread_struct * t = ¤t->thread; struct tss_struct * tss; unsigned long *bitmap; if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) return -EINVAL; if (turn_on && !capable(CAP_SYS_RAWIO)) return -EPERM; /* * If it's the first ioperm() call in this thread's lifetime, set the * IO bitmap up. ioperm() is much less timing critical than clone(), * this is why we delay this operation until now: */ if (!t->io_bitmap_ptr) { bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); if (!bitmap) return -ENOMEM; memset(bitmap, 0xff, IO_BITMAP_BYTES); t->io_bitmap_ptr = bitmap; set_thread_flag(TIF_IO_BITMAP); } /* * do it in the per-thread copy and in the TSS ... * * Disable preemption via get_cpu() - we must not switch away * because the ->io_bitmap_max value must match the bitmap * contents: */ tss = &per_cpu(init_tss, get_cpu()); set_bitmap(t->io_bitmap_ptr, from, num, !turn_on); /* * Search for a (possibly new) maximum. This is simple and stupid, * to keep it obviously correct: */ max_long = 0; for (i = 0; i < IO_BITMAP_LONGS; i++) if (t->io_bitmap_ptr[i] != ~0UL) max_long = i; bytes = (max_long + 1) * sizeof(long); bytes_updated = max(bytes, t->io_bitmap_max); t->io_bitmap_max = bytes; /* Update the TSS: */ memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated); put_cpu(); return 0; } /* * sys_iopl has to be used when you want to access the IO ports * beyond the 0x3ff range: to get the full 65536 ports bitmapped * you'd need 8kB of bitmaps/process, which is a bit excessive. * * Here we just change the eflags value on the stack: we allow * only the super-user to do it. This depends on the stack-layout * on system-call entry - see also fork() and the signal handling * code. */ asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs) { unsigned int old = (regs->eflags >> 12) & 3; if (level > 3) return -EINVAL; /* Trying to gain more privileges? */ if (level > old) { if (!capable(CAP_SYS_RAWIO)) return -EPERM; } regs->eflags = (regs->eflags &~ X86_EFLAGS_IOPL) | (level << 12); return 0; }