evo-syzkaller-ppdev-syzlang

Generates complete syzkaller syzlang device driver descriptions for the Linux ppdev (parallel port) subsystem.

Overview

Produces two files:

• dev_ppdev.txt — syzlang descriptions with includes, resource, opener, all 28 ioctl variants, struct, and flag groups
• dev_ppdev.txt.const — architecture-specific constant values for amd64 and 386

Key Domain Knowledge

IOCTL Encoding (x86)

• ppdev uses magic type char 'p' (0x70) for all ioctls
• _IO: dir=0, size=0
• _IOR: dir=2 (bit 31), size encoded in bits 16-29
• _IOW: dir=1 (bit 30), size encoded in bits 16-29
• Formula: (dir << 30) | (size << 16) | (type << 8) | nr

Architecture Differences

• struct timeval is 16 bytes on amd64 (two 8-byte longs) but 8 bytes on 386 (two 4-byte longs)
• This causes PPGETTIME and PPSETTIME to have different ioctl numbers per architecture
• All other ioctls have identical values across amd64 and 386

Complete IOCTL Coverage (28 total)

• 4 _IO (no-arg): PPCLAIM, PPRELEASE, PPYIELD, PPEXCL
• 14 _IOW (input): PPSETMODE, PPWSTATUS(obsolete), PPWCONTROL, PPWDATA, PPWECONTROL(obsolete), PPWFIFO(obsolete), PPFCONTROL, PPDATADIR, PPNEGOT, PPWCTLONIRQ, PPSETPHASE, PPSETTIME, PPSETFLAGS
• 10 _IOR (output): PPRSTATUS, PPRCONTROL, PPRDATA, PPRECONTROL(obsolete), PPRFIFO(obsolete), PPCLRIRQ, PPGETTIME, PPGETMODES, PPGETMODE, PPGETPHASE, PPGETFLAGS

Syzlang Direction Mapping

• _IOR (kernel writes to user) → ptr[out, ...]
• _IOW (user writes to kernel) → ptr[in, ...]
• _IO (no data) → omit third argument entirely

Flag Groups

• ieee1284_modes: 12 IEEE 1284 protocol mode constants from linux/parport.h
• ppdev_flags: PP_FASTWRITE, PP_FASTREAD, PP_W91284PIC from linux/ppdev.h

Const File Format

• Header: # Code generated by syz-sysgen. DO NOT EDIT.
• Architecture line: arches = 386, amd64
• Per-constant: NAME = 386:value, amd64:value (arch-qualified format)
• Values are decimal integers
• Constants must be sorted alphabetically (syzkaller convention)

Usage

import sys
sys.path.insert(0, '/app/environment/skills/evo-syzkaller-ppdev-syzlang/scripts')
from generate import write_files
write_files('/opt/syzkaller/sys/linux/dev_ppdev.txt', '/opt/syzkaller/sys/linux/dev_ppdev.txt.const')

Verification

cd /opt/syzkaller
make descriptions
make all TARGETOS=linux TARGETARCH=amd64