src/tools/miri/src/shims/unix/linux/foreign_items.rs

   1 use rustc_span::Symbol;
   2 use rustc_target::spec::abi::Abi;
   3
   4 use crate::*;
   5 use shims::foreign_items::EmulateByNameResult;
   6 use shims::unix::fs::EvalContextExt as _;
   7 use shims::unix::linux::sync::futex;
   8 use shims::unix::sync::EvalContextExt as _;
   9 use shims::unix::thread::EvalContextExt as _;
  10
  11 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
  12 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
  13     fn emulate_foreign_item_by_name(
  14         &mut self,
  15         link_name: Symbol,
  16         abi: Abi,
  17         args: &[OpTy<'tcx, Provenance>],
  18         dest: &PlaceTy<'tcx, Provenance>,
  19     ) -> InterpResult<'tcx, EmulateByNameResult<'mir, 'tcx>> {
  20         let this = self.eval_context_mut();
  21
  22         // See `fn emulate_foreign_item_by_name` in `shims/foreign_items.rs` for the general pattern.
  23
  24         match link_name.as_str() {
  25             // errno
  26             "__errno_location" => {
  27                 let [] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  28                 let errno_place = this.last_error_place()?;
  29                 this.write_scalar(errno_place.to_ref(this).to_scalar(), dest)?;
  30             }
  31
  32             // File related shims (but also see "syscall" below for statx)
  33             "readdir64" => {
  34                 let [dirp] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  35                 let result = this.linux_readdir64(dirp)?;
  36                 this.write_scalar(result, dest)?;
  37             }
  38             // Linux-only
  39             "sync_file_range" => {
  40                 let [fd, offset, nbytes, flags] =
  41                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  42                 let result = this.sync_file_range(fd, offset, nbytes, flags)?;
  43                 this.write_scalar(result, dest)?;
  44             }
  45
  46             // Threading
  47             "pthread_condattr_setclock" => {
  48                 let [attr, clock_id] =
  49                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  50                 let result = this.pthread_condattr_setclock(attr, clock_id)?;
  51                 this.write_scalar(result, dest)?;
  52             }
  53             "pthread_condattr_getclock" => {
  54                 let [attr, clock_id] =
  55                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  56                 let result = this.pthread_condattr_getclock(attr, clock_id)?;
  57                 this.write_scalar(result, dest)?;
  58             }
  59             "pthread_setname_np" => {
  60                 let [thread, name] =
  61                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  62                 let max_len = 16;
  63                 let res = this.pthread_setname_np(
  64                     this.read_scalar(thread)?,
  65                     this.read_scalar(name)?,
  66                     max_len,
  67                 )?;
  68                 this.write_scalar(res, dest)?;
  69             }
  70             "pthread_getname_np" => {
  71                 let [thread, name, len] =
  72                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  73                 let res = this.pthread_getname_np(
  74                     this.read_scalar(thread)?,
  75                     this.read_scalar(name)?,
  76                     this.read_scalar(len)?,
  77                 )?;
  78                 this.write_scalar(res, dest)?;
  79             }
  80
  81             // Dynamically invoked syscalls
  82             "syscall" => {
  83                 // We do not use `check_shim` here because `syscall` is variadic. The argument
  84                 // count is checked bellow.
  85                 this.check_abi_and_shim_symbol_clash(abi, Abi::C { unwind: false }, link_name)?;
  86                 // The syscall variadic function is legal to call with more arguments than needed,
  87                 // extra arguments are simply ignored. The important check is that when we use an
  88                 // argument, we have to also check all arguments *before* it to ensure that they
  89                 // have the right type.
  90
  91                 let sys_getrandom = this.eval_libc("SYS_getrandom")?.to_machine_usize(this)?;
  92
  93                 let sys_statx = this.eval_libc("SYS_statx")?.to_machine_usize(this)?;
  94
  95                 let sys_futex = this.eval_libc("SYS_futex")?.to_machine_usize(this)?;
  96
  97                 if args.is_empty() {
  98                     throw_ub_format!(
  99                         "incorrect number of arguments for syscall: got 0, expected at least 1"
 100                     );
 101                 }
 102                 match this.read_scalar(&args[0])?.to_machine_usize(this)? {
 103                     // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 104                     // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 105                     id if id == sys_getrandom => {
 106                         // The first argument is the syscall id, so skip over it.
 107                         if args.len() < 4 {
 108                             throw_ub_format!(
 109                                 "incorrect number of arguments for `getrandom` syscall: got {}, expected at least 4",
 110                                 args.len()
 111                             );
 112                         }
 113                         getrandom(this, &args[1], &args[2], &args[3], dest)?;
 114                     }
 115                     // `statx` is used by `libstd` to retrieve metadata information on `linux`
 116                     // instead of using `stat`,`lstat` or `fstat` as on `macos`.
 117                     id if id == sys_statx => {
 118                         // The first argument is the syscall id, so skip over it.
 119                         if args.len() < 6 {
 120                             throw_ub_format!(
 121                                 "incorrect number of arguments for `statx` syscall: got {}, expected at least 6",
 122                                 args.len()
 123                             );
 124                         }
 125                         let result =
 126                             this.linux_statx(&args[1], &args[2], &args[3], &args[4], &args[5])?;
 127                         this.write_scalar(Scalar::from_machine_isize(result.into(), this), dest)?;
 128                     }
 129                     // `futex` is used by some synchonization primitives.
 130                     id if id == sys_futex => {
 131                         futex(this, &args[1..], dest)?;
 132                     }
 133                     id => {
 134                         this.handle_unsupported(format!("can't execute syscall with ID {id}"))?;
 135                         return Ok(EmulateByNameResult::AlreadyJumped);
 136                     }
 137                 }
 138             }
 139
 140             // Miscelanneous
 141             "getrandom" => {
 142                 let [ptr, len, flags] =
 143                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 144                 getrandom(this, ptr, len, flags, dest)?;
 145             }
 146             "sched_getaffinity" => {
 147                 let [pid, cpusetsize, mask] =
 148                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 149                 this.read_scalar(pid)?.to_i32()?;
 150                 this.read_scalar(cpusetsize)?.to_machine_usize(this)?;
 151                 this.deref_operand(mask)?;
 152                 // FIXME: we just return an error; `num_cpus` then falls back to `sysconf`.
 153                 let einval = this.eval_libc("EINVAL")?;
 154                 this.set_last_error(einval)?;
 155                 this.write_scalar(Scalar::from_i32(-1), dest)?;
 156             }
 157
 158             // Incomplete shims that we "stub out" just to get pre-main initialization code to work.
 159             // These shims are enabled only when the caller is in the standard library.
 160             "pthread_getattr_np" if this.frame_in_std() => {
 161                 let [_thread, _attr] =
 162                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 163                 this.write_null(dest)?;
 164             }
 165
 166             _ => return Ok(EmulateByNameResult::NotSupported),
 167         };
 168
 169         Ok(EmulateByNameResult::NeedsJumping)
 170     }
 171 }
 172
 173 // Shims the linux `getrandom` syscall.
 174 fn getrandom<'tcx>(
 175     this: &mut MiriInterpCx<'_, 'tcx>,
 176     ptr: &OpTy<'tcx, Provenance>,
 177     len: &OpTy<'tcx, Provenance>,
 178     flags: &OpTy<'tcx, Provenance>,
 179     dest: &PlaceTy<'tcx, Provenance>,
 180 ) -> InterpResult<'tcx> {
 181     let ptr = this.read_pointer(ptr)?;
 182     let len = this.read_scalar(len)?.to_machine_usize(this)?;
 183
 184     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 185     // neither of which have any effect on our current PRNG.
 186     // See <https://github.com/rust-lang/rust/pull/79196> for a discussion of argument sizes.
 187     let _flags = this.read_scalar(flags)?.to_i32();
 188
 189     this.gen_random(ptr, len)?;
 190     this.write_scalar(Scalar::from_machine_usize(len, this), dest)?;
 191     Ok(())
 192 }