Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | * This contains the io-permission bitmap code - written by obz, with changes |
mboton@gmail.com | ccafa59 | 2008-01-30 13:33:10 +0100 | [diff] [blame] | 3 | * by Linus. 32/64 bits code unification by Miguel Botón. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4 | */ |
| 5 | |
| 6 | #include <linux/sched.h> |
| 7 | #include <linux/kernel.h> |
Randy Dunlap | a941564 | 2006-01-11 12:17:48 -0800 | [diff] [blame] | 8 | #include <linux/capability.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 9 | #include <linux/errno.h> |
| 10 | #include <linux/types.h> |
| 11 | #include <linux/ioport.h> |
| 12 | #include <linux/smp.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 13 | #include <linux/stddef.h> |
| 14 | #include <linux/slab.h> |
| 15 | #include <linux/thread_info.h> |
Adrian Bunk | ca906e4 | 2007-05-02 19:27:10 +0200 | [diff] [blame] | 16 | #include <linux/syscalls.h> |
Akinobu Mita | da1016d | 2011-02-16 23:48:35 +0900 | [diff] [blame] | 17 | #include <linux/bitmap.h> |
Jaswinder Singh | bbc1f69 | 2008-07-21 21:34:13 +0530 | [diff] [blame] | 18 | #include <asm/syscalls.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 19 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | /* |
| 21 | * this changes the io permissions bitmap in the current task. |
| 22 | */ |
| 23 | asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) |
| 24 | { |
Jaswinder Singh Rajput | 5866e1b | 2009-01-04 16:29:32 +0530 | [diff] [blame] | 25 | struct thread_struct *t = ¤t->thread; |
| 26 | struct tss_struct *tss; |
mboton@gmail.com | ccafa59 | 2008-01-30 13:33:10 +0100 | [diff] [blame] | 27 | unsigned int i, max_long, bytes, bytes_updated; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 28 | |
| 29 | if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) |
| 30 | return -EINVAL; |
| 31 | if (turn_on && !capable(CAP_SYS_RAWIO)) |
| 32 | return -EPERM; |
| 33 | |
| 34 | /* |
| 35 | * If it's the first ioperm() call in this thread's lifetime, set the |
| 36 | * IO bitmap up. ioperm() is much less timing critical than clone(), |
| 37 | * this is why we delay this operation until now: |
| 38 | */ |
| 39 | if (!t->io_bitmap_ptr) { |
Thomas Gleixner | 9a211ab | 2008-01-30 13:30:24 +0100 | [diff] [blame] | 40 | unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); |
| 41 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 42 | if (!bitmap) |
| 43 | return -ENOMEM; |
| 44 | |
| 45 | memset(bitmap, 0xff, IO_BITMAP_BYTES); |
| 46 | t->io_bitmap_ptr = bitmap; |
Stephane Eranian | b3cf257 | 2006-07-09 21:12:39 -0400 | [diff] [blame] | 47 | set_thread_flag(TIF_IO_BITMAP); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | } |
| 49 | |
| 50 | /* |
| 51 | * do it in the per-thread copy and in the TSS ... |
| 52 | * |
| 53 | * Disable preemption via get_cpu() - we must not switch away |
| 54 | * because the ->io_bitmap_max value must match the bitmap |
| 55 | * contents: |
| 56 | */ |
Andy Lutomirski | 24933b8 | 2015-03-05 19:19:05 -0800 | [diff] [blame] | 57 | tss = &per_cpu(cpu_tss, get_cpu()); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 58 | |
Akinobu Mita | da1016d | 2011-02-16 23:48:35 +0900 | [diff] [blame] | 59 | if (turn_on) |
| 60 | bitmap_clear(t->io_bitmap_ptr, from, num); |
| 61 | else |
| 62 | bitmap_set(t->io_bitmap_ptr, from, num); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | |
| 64 | /* |
| 65 | * Search for a (possibly new) maximum. This is simple and stupid, |
| 66 | * to keep it obviously correct: |
| 67 | */ |
| 68 | max_long = 0; |
| 69 | for (i = 0; i < IO_BITMAP_LONGS; i++) |
| 70 | if (t->io_bitmap_ptr[i] != ~0UL) |
| 71 | max_long = i; |
| 72 | |
mboton@gmail.com | ccafa59 | 2008-01-30 13:33:10 +0100 | [diff] [blame] | 73 | bytes = (max_long + 1) * sizeof(unsigned long); |
| 74 | bytes_updated = max(bytes, t->io_bitmap_max); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 75 | |
mboton@gmail.com | ccafa59 | 2008-01-30 13:33:10 +0100 | [diff] [blame] | 76 | t->io_bitmap_max = bytes; |
| 77 | |
mboton@gmail.com | ccafa59 | 2008-01-30 13:33:10 +0100 | [diff] [blame] | 78 | /* Update the TSS: */ |
| 79 | memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 80 | |
| 81 | put_cpu(); |
| 82 | |
| 83 | return 0; |
| 84 | } |
| 85 | |
| 86 | /* |
| 87 | * sys_iopl has to be used when you want to access the IO ports |
| 88 | * beyond the 0x3ff range: to get the full 65536 ports bitmapped |
| 89 | * you'd need 8kB of bitmaps/process, which is a bit excessive. |
| 90 | * |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 91 | * Here we just change the flags value on the stack: we allow |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | * only the super-user to do it. This depends on the stack-layout |
| 93 | * on system-call entry - see also fork() and the signal handling |
| 94 | * code. |
| 95 | */ |
Al Viro | b3af11a | 2012-11-19 22:00:52 -0500 | [diff] [blame] | 96 | SYSCALL_DEFINE1(iopl, unsigned int, level) |
Chris Wright | a1bf250 | 2008-01-30 13:33:10 +0100 | [diff] [blame] | 97 | { |
Al Viro | b3af11a | 2012-11-19 22:00:52 -0500 | [diff] [blame] | 98 | struct pt_regs *regs = current_pt_regs(); |
Chris Wright | a1bf250 | 2008-01-30 13:33:10 +0100 | [diff] [blame] | 99 | unsigned int old = (regs->flags >> 12) & 3; |
Brian Gerst | 27f5955 | 2009-12-09 19:01:52 -0500 | [diff] [blame] | 100 | struct thread_struct *t = ¤t->thread; |
Chris Wright | a1bf250 | 2008-01-30 13:33:10 +0100 | [diff] [blame] | 101 | |
| 102 | if (level > 3) |
| 103 | return -EINVAL; |
| 104 | /* Trying to gain more privileges? */ |
| 105 | if (level > old) { |
| 106 | if (!capable(CAP_SYS_RAWIO)) |
| 107 | return -EPERM; |
| 108 | } |
| 109 | regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12); |
Brian Gerst | 27f5955 | 2009-12-09 19:01:52 -0500 | [diff] [blame] | 110 | t->iopl = level << 12; |
| 111 | set_iopl_mask(t->iopl); |
Chris Wright | a1bf250 | 2008-01-30 13:33:10 +0100 | [diff] [blame] | 112 | |
| 113 | return 0; |
| 114 | } |