diff options
Diffstat (limited to 'arch/x86_64/kernel/ioport_64.c')
| -rw-r--r-- | arch/x86_64/kernel/ioport_64.c | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/arch/x86_64/kernel/ioport_64.c b/arch/x86_64/kernel/ioport_64.c new file mode 100644 index 000000000000..653efa30b0f4 --- /dev/null +++ b/arch/x86_64/kernel/ioport_64.c @@ -0,0 +1,119 @@ +/* + * linux/arch/x86_64/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/capability.h> +#include <linux/errno.h> +#include <linux/types.h> +#include <linux/ioport.h> +#include <linux/smp.h> +#include <linux/stddef.h> +#include <linux/slab.h> +#include <linux/thread_info.h> +#include <linux/syscalls.h> + +/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */ +static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value) +{ + int i; + if (new_value) + for (i = base; i < base + extent; i++) + __set_bit(i, bitmap); + else + for (i = base; i < base + extent; i++) + clear_bit(i, bitmap); +} + +/* + * this changes the io permissions bitmap in the current task. + */ +asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) +{ + unsigned int i, max_long, bytes, bytes_updated; + struct thread_struct * t = ¤t->thread; + struct tss_struct * tss; + unsigned long *bitmap; + + if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) + 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->io_bitmap_ptr) { + bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); + if (!bitmap) + return -ENOMEM; + + memset(bitmap, 0xff, IO_BITMAP_BYTES); + t->io_bitmap_ptr = bitmap; + set_thread_flag(TIF_IO_BITMAP); + } + + /* + * do it in the per-thread copy and in the TSS ... + * + * Disable preemption via get_cpu() - we must not switch away + * because the ->io_bitmap_max value must match the bitmap + * contents: + */ + tss = &per_cpu(init_tss, get_cpu()); + + set_bitmap(t->io_bitmap_ptr, from, num, !turn_on); + + /* + * Search for a (possibly new) maximum. This is simple and stupid, + * to keep it obviously correct: + */ + max_long = 0; + for (i = 0; i < IO_BITMAP_LONGS; i++) + if (t->io_bitmap_ptr[i] != ~0UL) + max_long = i; + + bytes = (max_long + 1) * sizeof(long); + bytes_updated = max(bytes, t->io_bitmap_max); + + t->io_bitmap_max = bytes; + + /* Update the TSS: */ + memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated); + + put_cpu(); + + 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 long sys_iopl(unsigned int level, struct pt_regs *regs) +{ + 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 &~ X86_EFLAGS_IOPL) | (level << 12); + return 0; +} |