| 1 | /* |
| 2 | * This contains the io-permission bitmap code - written by obz, with changes |
| 3 | * by Linus. 32/64 bits code unification by Miguel Botón. |
| 4 | */ |
| 5 | |
| 6 | #include <linux/sched.h> |
| 7 | #include <linux/kernel.h> |
| 8 | #include <linux/capability.h> |
| 9 | #include <linux/errno.h> |
| 10 | #include <linux/types.h> |
| 11 | #include <linux/ioport.h> |
| 12 | #include <linux/smp.h> |
| 13 | #include <linux/stddef.h> |
| 14 | #include <linux/slab.h> |
| 15 | #include <linux/thread_info.h> |
| 16 | #include <linux/syscalls.h> |
| 17 | #include <asm/syscalls.h> |
| 18 | |
| 19 | /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */ |
| 20 | static void set_bitmap(unsigned long *bitmap, unsigned int base, |
| 21 | unsigned int extent, int new_value) |
| 22 | { |
| 23 | unsigned int i; |
| 24 | |
| 25 | for (i = base; i < base + extent; i++) { |
| 26 | if (new_value) |
| 27 | __set_bit(i, bitmap); |
| 28 | else |
| 29 | __clear_bit(i, bitmap); |
| 30 | } |
| 31 | } |
| 32 | |
| 33 | /* |
| 34 | * this changes the io permissions bitmap in the current task. |
| 35 | */ |
| 36 | asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) |
| 37 | { |
| 38 | struct thread_struct * t = ¤t->thread; |
| 39 | struct tss_struct * tss; |
| 40 | unsigned int i, max_long, bytes, bytes_updated; |
| 41 | |
| 42 | if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) |
| 43 | return -EINVAL; |
| 44 | if (turn_on && !capable(CAP_SYS_RAWIO)) |
| 45 | return -EPERM; |
| 46 | |
| 47 | /* |
| 48 | * If it's the first ioperm() call in this thread's lifetime, set the |
| 49 | * IO bitmap up. ioperm() is much less timing critical than clone(), |
| 50 | * this is why we delay this operation until now: |
| 51 | */ |
| 52 | if (!t->io_bitmap_ptr) { |
| 53 | unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); |
| 54 | |
| 55 | if (!bitmap) |
| 56 | return -ENOMEM; |
| 57 | |
| 58 | memset(bitmap, 0xff, IO_BITMAP_BYTES); |
| 59 | t->io_bitmap_ptr = bitmap; |
| 60 | set_thread_flag(TIF_IO_BITMAP); |
| 61 | } |
| 62 | |
| 63 | /* |
| 64 | * do it in the per-thread copy and in the TSS ... |
| 65 | * |
| 66 | * Disable preemption via get_cpu() - we must not switch away |
| 67 | * because the ->io_bitmap_max value must match the bitmap |
| 68 | * contents: |
| 69 | */ |
| 70 | tss = &per_cpu(init_tss, get_cpu()); |
| 71 | |
| 72 | set_bitmap(t->io_bitmap_ptr, from, num, !turn_on); |
| 73 | |
| 74 | /* |
| 75 | * Search for a (possibly new) maximum. This is simple and stupid, |
| 76 | * to keep it obviously correct: |
| 77 | */ |
| 78 | max_long = 0; |
| 79 | for (i = 0; i < IO_BITMAP_LONGS; i++) |
| 80 | if (t->io_bitmap_ptr[i] != ~0UL) |
| 81 | max_long = i; |
| 82 | |
| 83 | bytes = (max_long + 1) * sizeof(unsigned long); |
| 84 | bytes_updated = max(bytes, t->io_bitmap_max); |
| 85 | |
| 86 | t->io_bitmap_max = bytes; |
| 87 | |
| 88 | #ifdef CONFIG_X86_32 |
| 89 | /* |
| 90 | * Sets the lazy trigger so that the next I/O operation will |
| 91 | * reload the correct bitmap. |
| 92 | * Reset the owner so that a process switch will not set |
| 93 | * tss->io_bitmap_base to IO_BITMAP_OFFSET. |
| 94 | */ |
| 95 | tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; |
| 96 | tss->io_bitmap_owner = NULL; |
| 97 | #else |
| 98 | /* Update the TSS: */ |
| 99 | memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated); |
| 100 | #endif |
| 101 | |
| 102 | put_cpu(); |
| 103 | |
| 104 | return 0; |
| 105 | } |
| 106 | |
| 107 | /* |
| 108 | * sys_iopl has to be used when you want to access the IO ports |
| 109 | * beyond the 0x3ff range: to get the full 65536 ports bitmapped |
| 110 | * you'd need 8kB of bitmaps/process, which is a bit excessive. |
| 111 | * |
| 112 | * Here we just change the flags value on the stack: we allow |
| 113 | * only the super-user to do it. This depends on the stack-layout |
| 114 | * on system-call entry - see also fork() and the signal handling |
| 115 | * code. |
| 116 | */ |
| 117 | static int do_iopl(unsigned int level, struct pt_regs *regs) |
| 118 | { |
| 119 | unsigned int old = (regs->flags >> 12) & 3; |
| 120 | |
| 121 | if (level > 3) |
| 122 | return -EINVAL; |
| 123 | /* Trying to gain more privileges? */ |
| 124 | if (level > old) { |
| 125 | if (!capable(CAP_SYS_RAWIO)) |
| 126 | return -EPERM; |
| 127 | } |
| 128 | regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12); |
| 129 | |
| 130 | return 0; |
| 131 | } |
| 132 | |
| 133 | #ifdef CONFIG_X86_32 |
| 134 | asmlinkage long sys_iopl(unsigned long regsp) |
| 135 | { |
| 136 | struct pt_regs *regs = (struct pt_regs *)®sp; |
| 137 | unsigned int level = regs->bx; |
| 138 | struct thread_struct *t = ¤t->thread; |
| 139 | int rc; |
| 140 | |
| 141 | rc = do_iopl(level, regs); |
| 142 | if (rc < 0) |
| 143 | goto out; |
| 144 | |
| 145 | t->iopl = level << 12; |
| 146 | set_iopl_mask(t->iopl); |
| 147 | out: |
| 148 | return rc; |
| 149 | } |
| 150 | #else |
| 151 | asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs) |
| 152 | { |
| 153 | return do_iopl(level, regs); |
| 154 | } |
| 155 | #endif |