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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 | /* * linux/arch/i386/kernel/ioport.c * * This contains the io-permission bitmap code - written by obz, with changes * by Linus. */ #include <linux/sched.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/types.h> #include <linux/ioport.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/smp_lock.h> #include <linux/stddef.h> /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */ static void set_bitmap(unsigned long *bitmap, short base, short extent, int new_value) { int mask; unsigned long *bitmap_base = bitmap + (base >> 5); unsigned short low_index = base & 0x1f; int length = low_index + extent; if (low_index != 0) { mask = (~0 << low_index); if (length < 32) mask &= ~(~0 << length); if (new_value) *bitmap_base++ |= mask; else *bitmap_base++ &= ~mask; length -= 32; } mask = (new_value ? ~0 : 0); while (length >= 32) { *bitmap_base++ = mask; length -= 32; } if (length > 0) { mask = ~(~0 << length); if (new_value) *bitmap_base++ |= mask; else *bitmap_base++ &= ~mask; } } /* * this changes the io permissions bitmap in the current task. */ asmlinkage int sys_ioperm(unsigned long from, unsigned long num, int turn_on) { struct thread_struct * t = ¤t->thread; struct tss_struct * tss = init_tss + smp_processor_id(); if ((from + num <= from) || (from + num > IO_BITMAP_SIZE*32)) 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->ioperm) { /* * just in case ... */ memset(t->io_bitmap,0xff,(IO_BITMAP_SIZE+1)*4); t->ioperm = 1; } /* * do it in the per-thread copy and in the TSS ... */ set_bitmap(t->io_bitmap, from, num, !turn_on); if (tss->bitmap == IO_BITMAP_OFFSET) { /* already active? */ set_bitmap(tss->io_bitmap, from, num, !turn_on); } else { memcpy(tss->io_bitmap, t->io_bitmap, IO_BITMAP_BYTES); tss->bitmap = IO_BITMAP_OFFSET; /* Activate it in the TSS */ } 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 int sys_iopl(unsigned long unused) { struct pt_regs * regs = (struct pt_regs *) &unused; unsigned int level = regs->ebx; 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 & 0xffffcfff) | (level << 12); return 0; } |