src/shims/unix/linux/foreign_items.rs

   1 use rustc_middle::mir;
   2 use rustc_span::Symbol;
   3 use rustc_target::spec::abi::Abi;
   4
   5 use crate::*;
   6 use shims::foreign_items::EmulateByNameResult;
   7 use shims::unix::fs::EvalContextExt as _;
   8 use shims::unix::linux::sync::futex;
   9 use shims::unix::sync::EvalContextExt as _;
  10 use shims::unix::thread::EvalContextExt as _;
  11
  12 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  13 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  14     fn emulate_foreign_item_by_name(
  15         &mut self,
  16         link_name: Symbol,
  17         abi: Abi,
  18         args: &[OpTy<'tcx, Tag>],
  19         dest: &PlaceTy<'tcx, Tag>,
  20         _ret: mir::BasicBlock,
  21     ) -> InterpResult<'tcx, EmulateByNameResult<'mir, 'tcx>> {
  22         let this = self.eval_context_mut();
  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             // These symbols have different names on Linux and macOS, which is the only reason they are not
  34             // in the `posix` module.
  35             "close" => {
  36                 let [fd] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  37                 let result = this.close(fd)?;
  38                 this.write_scalar(Scalar::from_i32(result), dest)?;
  39             }
  40             "opendir" => {
  41                 let [name] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  42                 let result = this.opendir(name)?;
  43                 this.write_scalar(result, dest)?;
  44             }
  45             "readdir64" => {
  46                 let [dirp] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  47                 let result = this.linux_readdir64(dirp)?;
  48                 this.write_scalar(result, dest)?;
  49             }
  50             "ftruncate64" => {
  51                 let [fd, length] =
  52                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  53                 let result = this.ftruncate64(fd, length)?;
  54                 this.write_scalar(Scalar::from_i32(result), dest)?;
  55             }
  56             // Linux-only
  57             "posix_fadvise" => {
  58                 let [fd, offset, len, advice] =
  59                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  60                 this.read_scalar(fd)?.to_i32()?;
  61                 this.read_scalar(offset)?.to_machine_isize(this)?;
  62                 this.read_scalar(len)?.to_machine_isize(this)?;
  63                 this.read_scalar(advice)?.to_i32()?;
  64                 // fadvise is only informational, we can ignore it.
  65                 this.write_null(dest)?;
  66             }
  67             "sync_file_range" => {
  68                 let [fd, offset, nbytes, flags] =
  69                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  70                 let result = this.sync_file_range(fd, offset, nbytes, flags)?;
  71                 this.write_scalar(Scalar::from_i32(result), dest)?;
  72             }
  73
  74             // Time related shims
  75             "clock_gettime" => {
  76                 // This is a POSIX function but it has only been tested on linux.
  77                 let [clk_id, tp] =
  78                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  79                 let result = this.clock_gettime(clk_id, tp)?;
  80                 this.write_scalar(Scalar::from_i32(result), dest)?;
  81             }
  82
  83             // Querying system information
  84             "pthread_attr_getstack" => {
  85                 // We don't support "pthread_attr_setstack", so we just pretend all stacks have the same values here.
  86                 let [attr_place, addr_place, size_place] =
  87                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
  88                 this.deref_operand(attr_place)?;
  89                 let addr_place = this.deref_operand(addr_place)?;
  90                 let size_place = this.deref_operand(size_place)?;
  91
  92                 this.write_scalar(
  93                     Scalar::from_uint(STACK_ADDR, this.pointer_size()),
  94                     &addr_place.into(),
  95                 )?;
  96                 this.write_scalar(
  97                     Scalar::from_uint(STACK_SIZE, this.pointer_size()),
  98                     &size_place.into(),
  99                 )?;
 100
 101                 // Return success (`0`).
 102                 this.write_null(dest)?;
 103             }
 104
 105             // Threading
 106             "prctl" => {
 107                 // prctl is variadic. (It is not documented like that in the manpage, but defined like that in the libc crate.)
 108                 this.check_abi_and_shim_symbol_clash(abi, Abi::C { unwind: false }, link_name)?;
 109                 let result = this.prctl(args)?;
 110                 this.write_scalar(Scalar::from_i32(result), dest)?;
 111             }
 112             "pthread_condattr_setclock" => {
 113                 let [attr, clock_id] =
 114                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 115                 let result = this.pthread_condattr_setclock(attr, clock_id)?;
 116                 this.write_scalar(Scalar::from_i32(result), dest)?;
 117             }
 118             "pthread_condattr_getclock" => {
 119                 let [attr, clock_id] =
 120                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 121                 let result = this.pthread_condattr_getclock(attr, clock_id)?;
 122                 this.write_scalar(Scalar::from_i32(result), dest)?;
 123             }
 124
 125             // Dynamically invoked syscalls
 126             "syscall" => {
 127                 // We do not use `check_shim` here because `syscall` is variadic. The argument
 128                 // count is checked bellow.
 129                 this.check_abi_and_shim_symbol_clash(abi, Abi::C { unwind: false }, link_name)?;
 130                 // The syscall variadic function is legal to call with more arguments than needed,
 131                 // extra arguments are simply ignored. The important check is that when we use an
 132                 // argument, we have to also check all arguments *before* it to ensure that they
 133                 // have the right type.
 134
 135                 let sys_getrandom = this.eval_libc("SYS_getrandom")?.to_machine_usize(this)?;
 136
 137                 let sys_statx = this.eval_libc("SYS_statx")?.to_machine_usize(this)?;
 138
 139                 let sys_futex = this.eval_libc("SYS_futex")?.to_machine_usize(this)?;
 140
 141                 if args.is_empty() {
 142                     throw_ub_format!(
 143                         "incorrect number of arguments for syscall: got 0, expected at least 1"
 144                     );
 145                 }
 146                 match this.read_scalar(&args[0])?.to_machine_usize(this)? {
 147                     // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 148                     // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 149                     id if id == sys_getrandom => {
 150                         // The first argument is the syscall id, so skip over it.
 151                         if args.len() < 4 {
 152                             throw_ub_format!(
 153                                 "incorrect number of arguments for `getrandom` syscall: got {}, expected at least 4",
 154                                 args.len()
 155                             );
 156                         }
 157                         getrandom(this, &args[1], &args[2], &args[3], dest)?;
 158                     }
 159                     // `statx` is used by `libstd` to retrieve metadata information on `linux`
 160                     // instead of using `stat`,`lstat` or `fstat` as on `macos`.
 161                     id if id == sys_statx => {
 162                         // The first argument is the syscall id, so skip over it.
 163                         if args.len() < 6 {
 164                             throw_ub_format!(
 165                                 "incorrect number of arguments for `statx` syscall: got {}, expected at least 6",
 166                                 args.len()
 167                             );
 168                         }
 169                         let result =
 170                             this.linux_statx(&args[1], &args[2], &args[3], &args[4], &args[5])?;
 171                         this.write_scalar(Scalar::from_machine_isize(result.into(), this), dest)?;
 172                     }
 173                     // `futex` is used by some synchonization primitives.
 174                     id if id == sys_futex => {
 175                         futex(this, &args[1..], dest)?;
 176                     }
 177                     id => {
 178                         this.handle_unsupported(format!("can't execute syscall with ID {}", id))?;
 179                         return Ok(EmulateByNameResult::AlreadyJumped);
 180                     }
 181                 }
 182             }
 183
 184             // Miscelanneous
 185             "getrandom" => {
 186                 let [ptr, len, flags] =
 187                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 188                 getrandom(this, ptr, len, flags, dest)?;
 189             }
 190             "sched_getaffinity" => {
 191                 let [pid, cpusetsize, mask] =
 192                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 193                 this.read_scalar(pid)?.to_i32()?;
 194                 this.read_scalar(cpusetsize)?.to_machine_usize(this)?;
 195                 this.deref_operand(mask)?;
 196                 // FIXME: we just return an error; `num_cpus` then falls back to `sysconf`.
 197                 let einval = this.eval_libc("EINVAL")?;
 198                 this.set_last_error(einval)?;
 199                 this.write_scalar(Scalar::from_i32(-1), dest)?;
 200             }
 201
 202             // Incomplete shims that we "stub out" just to get pre-main initialization code to work.
 203             // These shims are enabled only when the caller is in the standard library.
 204             "pthread_getattr_np" if this.frame_in_std() => {
 205                 let [_thread, _attr] =
 206                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 207                 this.write_null(dest)?;
 208             }
 209
 210             _ => return Ok(EmulateByNameResult::NotSupported),
 211         };
 212
 213         Ok(EmulateByNameResult::NeedsJumping)
 214     }
 215 }
 216
 217 // Shims the linux `getrandom` syscall.
 218 fn getrandom<'tcx>(
 219     this: &mut MiriEvalContext<'_, 'tcx>,
 220     ptr: &OpTy<'tcx, Tag>,
 221     len: &OpTy<'tcx, Tag>,
 222     flags: &OpTy<'tcx, Tag>,
 223     dest: &PlaceTy<'tcx, Tag>,
 224 ) -> InterpResult<'tcx> {
 225     let ptr = this.read_pointer(ptr)?;
 226     let len = this.read_scalar(len)?.to_machine_usize(this)?;
 227
 228     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 229     // neither of which have any effect on our current PRNG.
 230     // See <https://github.com/rust-lang/rust/pull/79196> for a discussion of argument sizes.
 231     let _flags = this.read_scalar(flags)?.to_i32();
 232
 233     this.gen_random(ptr, len)?;
 234     this.write_scalar(Scalar::from_machine_usize(len, this), dest)?;
 235     Ok(())
 236 }