I'm trying to wrap the
SG_IO ioctl call (i.e. trap it in the kernel) and have that dump the
data from (struct sg_io_hdr).dxferp.
Having issues with doing the kernel trap in the newer kernel versions
though (trying on 2.6.30). The syscall table is now read-only but for
some reason my set_memory_rw() call is failing... Any ideas how to do
this properly?
Here are the relevant bits of code:
unsigned long **find_sys_call_table(void)
{
unsigned long **sctable;
unsigned long ptr;
sctable = NULL;
for (ptr = (unsigned long)&unlock_kernel;
ptr < (unsigned long)&loops_per_jiffy;
ptr += sizeof(void *))
{
unsigned long *p;
p = (unsigned long *)ptr;
if (p[__NR_close] == (unsigned long) sys_close)
{
sctable = (unsigned long **)p;
return &sctable[0];
}
}
return NULL;
}
static int __init scsisniff_init_module(void)
{
if ( (sys_call_table = find_sys_call_table()) ) {
real_ioctl = (int(*)(unsigned int fd, unsigned int cmd,
unsigned long arg))sys_call_table[__NR_ioctl];
if ( set_memory_rw( (unsigned
long)sys_call_table[__NR_ioctl], 1 ) )
printk( "set_memory_rw: succeeded\n" );
else {
printk( "set_memory_rw: failed!\n" );
return -1;
}
sys_call_table[__NR_ioctl] = (unsigned long)my_ioctl;
}
else {
return -1;
}
return 0;
}
This gives me a lovely OOPS:
[ 71.143742] WARNING: at arch/x86/mm/pageattr.c:833
change_page_attr_set_clr+0x1a0/0x400()
[ 71.143745] Modules linked in: scsi_sniff(+) i915 binfmt_misc drm
i2c_algo_bit bridge stp bnep lp snd_hda_codec_analog snd_hda_intel
snd_hda_codec snd_hwdep snd_pcm_oss snd_mixer_oss snd_pcm
snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi snd_seq_midi_event
snd_seq snd_timer snd_seq_device video snd psmouse tpm_infineon tpm
ppdev soundcore serio_raw pcspkr intel_agp tpm_bios output heci(C)
iTCO_wdt iTCO_vendor_support parport_pc parport snd_page_alloc floppy
usbhid usb_storage e1000e
[ 71.143768] Pid: 3378, comm: insmod Tainted: G C
2.6.30.4custom-1.0 #6
[ 71.143769] Call Trace:
[ 71.143773] [<ffffffff802da6d5>] ? __vunmap+0xc5/0x110
[ 71.143775] [<ffffffff80235200>] ? change_page_attr_set_clr+0x1a0/0x400
[ 71.143778] [<ffffffff8024edf8>] warn_slowpath_common+0x78/0xd0
[ 71.143780] [<ffffffff8024ee5f>] warn_slowpath_null+0xf/0x20
[ 71.143783] [<ffffffff80235200>] change_page_attr_set_clr+0x1a0/0x400
[ 71.143785] [<ffffffffa0274050>] ? my_ioctl+0x0/0x120 [scsi_sniff]
[ 71.143789] [<ffffffff802a6dcd>] ? marker_update_probe_range+0x1dd/0x2d0
[ 71.143791] [<ffffffffa0277000>] ? scsisniff_init_module+0x0/0xf4
[scsi_sniff]
[ 71.143793] [<ffffffff80235b9a>] set_memory_rw+0x2a/0x30
[ 71.143796] [<ffffffff802ff000>] ? sys_fcntl+0x180/0x420
[ 71.143798] [<ffffffffa02770bb>] scsisniff_init_module+0xbb/0xf4
[scsi_sniff]
[ 71.143801] [<ffffffff8020a04c>] do_one_initcall+0x3c/0x180
[ 71.143804] [<ffffffff8026b7f3>] ? __blocking_notifier_call_chain+0x63/0x80
[ 71.143807] [<ffffffff8027dc0d>] sys_init_module+0xad/0x200
[ 71.143810] [<ffffffff80210fc2>] system_call_fastpath+0x16/0x1b
[ 71.143812] ---[ end trace 5b3efe312296b587 ]---
[ 71.143958] set_memory_rw: failed!
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