Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 | 2 | /* |
1da177e4 | 3 | * This contains the io-permission bitmap code - written by obz, with changes |
ccafa59a | 4 | * by Linus. 32/64 bits code unification by Miguel Botón. |
1da177e4 LT |
5 | */ |
6 | ||
7 | #include <linux/sched.h> | |
68db0cf1 | 8 | #include <linux/sched/task_stack.h> |
1da177e4 | 9 | #include <linux/kernel.h> |
a9415644 | 10 | #include <linux/capability.h> |
1da177e4 LT |
11 | #include <linux/errno.h> |
12 | #include <linux/types.h> | |
13 | #include <linux/ioport.h> | |
14 | #include <linux/smp.h> | |
1da177e4 LT |
15 | #include <linux/stddef.h> |
16 | #include <linux/slab.h> | |
17 | #include <linux/thread_info.h> | |
ca906e42 | 18 | #include <linux/syscalls.h> |
da1016df | 19 | #include <linux/bitmap.h> |
bbc1f698 | 20 | #include <asm/syscalls.h> |
b7ffc44d | 21 | #include <asm/desc.h> |
1da177e4 | 22 | |
1da177e4 LT |
23 | /* |
24 | * this changes the io permissions bitmap in the current task. | |
25 | */ | |
66f4e88c | 26 | long ksys_ioperm(unsigned long from, unsigned long num, int turn_on) |
1da177e4 | 27 | { |
5866e1b4 JSR |
28 | struct thread_struct *t = ¤t->thread; |
29 | struct tss_struct *tss; | |
ccafa59a | 30 | unsigned int i, max_long, bytes, bytes_updated; |
1da177e4 LT |
31 | |
32 | if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) | |
33 | return -EINVAL; | |
34 | if (turn_on && !capable(CAP_SYS_RAWIO)) | |
35 | return -EPERM; | |
36 | ||
37 | /* | |
38 | * If it's the first ioperm() call in this thread's lifetime, set the | |
39 | * IO bitmap up. ioperm() is much less timing critical than clone(), | |
40 | * this is why we delay this operation until now: | |
41 | */ | |
42 | if (!t->io_bitmap_ptr) { | |
9a211abe TG |
43 | unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); |
44 | ||
1da177e4 LT |
45 | if (!bitmap) |
46 | return -ENOMEM; | |
47 | ||
48 | memset(bitmap, 0xff, IO_BITMAP_BYTES); | |
49 | t->io_bitmap_ptr = bitmap; | |
b3cf2576 | 50 | set_thread_flag(TIF_IO_BITMAP); |
b7ffc44d | 51 | |
b7ceaec1 AL |
52 | /* |
53 | * Now that we have an IO bitmap, we need our TSS limit to be | |
54 | * correct. It's fine if we are preempted after doing this: | |
55 | * with TIF_IO_BITMAP set, context switches will keep our TSS | |
56 | * limit correct. | |
57 | */ | |
b7ffc44d | 58 | preempt_disable(); |
b7ceaec1 | 59 | refresh_tss_limit(); |
b7ffc44d | 60 | preempt_enable(); |
1da177e4 LT |
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 | */ | |
c482feef | 70 | tss = &per_cpu(cpu_tss_rw, get_cpu()); |
1da177e4 | 71 | |
da1016df AM |
72 | if (turn_on) |
73 | bitmap_clear(t->io_bitmap_ptr, from, num); | |
74 | else | |
75 | bitmap_set(t->io_bitmap_ptr, from, num); | |
1da177e4 LT |
76 | |
77 | /* | |
78 | * Search for a (possibly new) maximum. This is simple and stupid, | |
79 | * to keep it obviously correct: | |
80 | */ | |
81 | max_long = 0; | |
82 | for (i = 0; i < IO_BITMAP_LONGS; i++) | |
83 | if (t->io_bitmap_ptr[i] != ~0UL) | |
84 | max_long = i; | |
85 | ||
ccafa59a | 86 | bytes = (max_long + 1) * sizeof(unsigned long); |
87 | bytes_updated = max(bytes, t->io_bitmap_max); | |
1da177e4 | 88 | |
ccafa59a | 89 | t->io_bitmap_max = bytes; |
90 | ||
ccafa59a | 91 | /* Update the TSS: */ |
92 | memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated); | |
1da177e4 LT |
93 | |
94 | put_cpu(); | |
95 | ||
96 | return 0; | |
97 | } | |
98 | ||
66f4e88c DB |
99 | SYSCALL_DEFINE3(ioperm, unsigned long, from, unsigned long, num, int, turn_on) |
100 | { | |
101 | return ksys_ioperm(from, num, turn_on); | |
102 | } | |
103 | ||
1da177e4 LT |
104 | /* |
105 | * sys_iopl has to be used when you want to access the IO ports | |
106 | * beyond the 0x3ff range: to get the full 65536 ports bitmapped | |
107 | * you'd need 8kB of bitmaps/process, which is a bit excessive. | |
108 | * | |
65ea5b03 | 109 | * Here we just change the flags value on the stack: we allow |
1da177e4 LT |
110 | * only the super-user to do it. This depends on the stack-layout |
111 | * on system-call entry - see also fork() and the signal handling | |
112 | * code. | |
113 | */ | |
b3af11af | 114 | SYSCALL_DEFINE1(iopl, unsigned int, level) |
1da177e4 | 115 | { |
b3af11af | 116 | struct pt_regs *regs = current_pt_regs(); |
27f59559 | 117 | struct thread_struct *t = ¤t->thread; |
1da177e4 | 118 | |
c29016cf AL |
119 | /* |
120 | * Careful: the IOPL bits in regs->flags are undefined under Xen PV | |
121 | * and changing them has no effect. | |
122 | */ | |
123 | unsigned int old = t->iopl >> X86_EFLAGS_IOPL_BIT; | |
124 | ||
1da177e4 LT |
125 | if (level > 3) |
126 | return -EINVAL; | |
127 | /* Trying to gain more privileges? */ | |
128 | if (level > old) { | |
129 | if (!capable(CAP_SYS_RAWIO)) | |
130 | return -EPERM; | |
131 | } | |
c29016cf AL |
132 | regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | |
133 | (level << X86_EFLAGS_IOPL_BIT); | |
134 | t->iopl = level << X86_EFLAGS_IOPL_BIT; | |
a1bf250a | 135 | set_iopl_mask(t->iopl); |
27f59559 BG |
136 | |
137 | return 0; | |
138 | } |