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 156