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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 | /* * This contains the io-permission bitmap code - written by obz, with changes * by Linus. 32/64 bits code unification by Miguel Botón. */ #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> #include <linux/bitmap.h> #include <asm/syscalls.h> /* * this changes the io permissions bitmap in the current task. */ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) { struct thread_struct *t = ¤t->thread; struct tss_struct *tss; unsigned int i, max_long, bytes, bytes_updated; 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) { unsigned long *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()); if (turn_on) bitmap_clear(t->io_bitmap_ptr, from, num); else bitmap_set(t->io_bitmap_ptr, from, num); /* * 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(unsigned 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 flags 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. */ SYSCALL_DEFINE1(iopl, unsigned int, level) { struct pt_regs *regs = current_pt_regs(); struct thread_struct *t = ¤t->thread; /* * Careful: the IOPL bits in regs->flags are undefined under Xen PV * and changing them has no effect. */ unsigned int old = t->iopl >> X86_EFLAGS_IOPL_BIT; if (level > 3) return -EINVAL; /* Trying to gain more privileges? */ if (level > old) { if (!capable(CAP_SYS_RAWIO)) return -EPERM; } regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << X86_EFLAGS_IOPL_BIT); t->iopl = level << X86_EFLAGS_IOPL_BIT; set_iopl_mask(t->iopl); return 0; } |