goblin/elf/
note.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
// Defined note types for GNU systems.

#[cfg(feature = "log")]
use log::debug;
#[cfg(feature = "alloc")]
use scroll::{IOread, IOwrite, Pread, Pwrite, SizeWith};

/// ABI information.
///
/// The descriptor consists of words:
///  * word 0: OS descriptor
///  * word 1: major version of the ABI
///  * word 2: minor version of the ABI
///  * word 3: subminor version of the ABI
pub const NT_GNU_ABI_TAG: u32 = 1;

/// Old name
pub const ELF_NOTE_ABI: u32 = NT_GNU_ABI_TAG;
// Known OSes.  These values can appear in word 0 of an
// `NT_GNU_ABI_TAG` note section entry.
pub const ELF_NOTE_OS_LINUX: u32 = 0;
pub const ELF_NOTE_OS_GNU: u32 = 1;
pub const ELF_NOTE_OS_SOLARIS2: u32 = 2;
pub const ELF_NOTE_OS_FREEBSD: u32 = 3;

/// Synthetic `hwcap` information.
///
/// The descriptor begins with two words:
///  * word 0: number of entries
///  * word 1: bitmask of enabled entries
///
/// Then follow variable-length entries, one byte followed by a '\0'-terminated
/// `hwcap` name string.  The byte gives the bit number to test if enabled,
/// `(1U << bit) & bitmask`.
pub const NT_GNU_HWCAP: u32 = 2;

/// Build ID bits as generated by ld --build-id.
///
/// The descriptor consists of any nonzero number of bytes.
pub const NT_GNU_BUILD_ID: u32 = 3;

/// Version note generated by GNU gold containing a version string.
pub const NT_GNU_GOLD_VERSION: u32 = 4;

/// Program property note
pub const NT_GNU_PROPERTY_TYPE_0: u32 = 5;

///Contains copy of prstatus struct.
pub const NT_PRSTATUS: u32 = 1;

///Contains copy of prpsinfo struct.
pub const NT_PRPSINFO: u32 = 3;

///Fields of siginfo_t.
pub const NT_SIGINFO: u32 = 0x5349_4749;

///Description of mapped files.
pub const NT_FILE: u32 = 0x4649_4c45;

#[derive(Clone, Copy, Debug)]
#[cfg_attr(feature = "alloc", derive(Pread, Pwrite, IOread, IOwrite, SizeWith))]
#[repr(C)]
/// Note section contents. Each entry in the note section begins with a header
/// of a fixed form.
pub struct Nhdr32 {
    /// Length of the note's name (includes the terminator)
    pub n_namesz: u32,
    /// Length of the note's descriptor
    pub n_descsz: u32,
    /// Type of the note
    pub n_type: u32,
}

// Declare that this is a plain type.
unsafe impl plain::Plain for Nhdr32 {}

#[derive(Clone, Copy, Debug)]
#[cfg_attr(feature = "alloc", derive(Pread, Pwrite, IOread, IOwrite, SizeWith))]
#[repr(C)]
/// Note section contents. Each entry in the note section begins with a header
/// of a fixed form.
pub struct Nhdr64 {
    /// Length of the note's name (includes the terminator)
    pub n_namesz: u64,
    /// Length of the note's descriptor.
    pub n_descsz: u64,
    /// Type of the note.
    pub n_type: u64,
}

// Declare that this is a plain type.
unsafe impl plain::Plain for Nhdr64 {}

if_alloc! {
    use crate::error;
    use crate::container;
    use scroll::ctx;
    use alloc::vec::Vec;

    /// An iterator over ELF binary notes in a note section or segment
    pub struct NoteDataIterator<'a> {
        pub data: &'a [u8],
        pub size: usize,
        pub offset: usize,
        pub ctx: (usize, container::Ctx), // (alignment, ctx)
    }

    impl<'a> Iterator for NoteDataIterator<'a> {
        type Item = error::Result<Note<'a>>;
        fn next(&mut self) -> Option<Self::Item> {
            if self.offset >= self.size {
                None
            } else {
                debug!("NoteIterator - {:#x}", self.offset);
                match self.data.gread_with(&mut self.offset, self.ctx) {
                    Ok(res) => Some(Ok(res)),
                    Err(e) => Some(Err(e))
                }
            }
        }
    }

    /// An iterator over ELF binary notes
    pub struct NoteIterator<'a> {
        pub iters: Vec<NoteDataIterator<'a>>,
        pub index: usize,
    }

    impl<'a> Iterator for NoteIterator<'a> {
        type Item = error::Result<Note<'a>>;
        fn next(&mut self) -> Option<Self::Item> {
            while self.index < self.iters.len() {
                if let Some(note_result) = self.iters[self.index].next() {
                    return Some(note_result);
                }

                self.index += 1;
            }

            None
        }
    }

    #[derive(Debug)]
    struct NoteHeader {
        n_namesz: usize,
        n_descsz: usize,
        n_type: u32,
    }

    impl From<Nhdr32> for NoteHeader {
        fn from(header: Nhdr32) -> Self {
            NoteHeader {
                n_namesz: header.n_namesz as usize,
                n_descsz: header.n_descsz as usize,
                n_type: header.n_type,
            }
        }
    }

    impl From<Nhdr64> for NoteHeader {
        fn from(header: Nhdr64) -> Self {
            NoteHeader {
                n_namesz: header.n_namesz as usize,
                n_descsz: header.n_descsz as usize,
                n_type: header.n_type as u32,
            }
        }
    }

    fn align(alignment: usize, offset: &mut usize) {
        let diff = *offset % alignment;
        if diff != 0 {
            *offset += alignment - diff;
        }
    }

    /// A 32/64 bit Note struct, with the name and desc pre-parsed
    #[derive(Debug)]
    pub struct Note<'a> {
        /// The type of this note
        pub n_type: u32,
        /// NUL terminated string, where `namesz` includes the terminator
        pub name: &'a str, // needs padding such that namesz + padding % {wordsize} == 0
        /// arbitrary data of length `descsz`
        pub desc: &'a [u8], // needs padding such that descsz + padding % {wordsize} == 0
    }

    impl<'a> Note<'a> {
        pub fn type_to_str(&self) -> &'static str {
            match self.n_type {
                NT_GNU_ABI_TAG => "NT_GNU_ABI_TAG",
                NT_GNU_HWCAP => "NT_GNU_HWCAP",
                NT_GNU_BUILD_ID => "NT_GNU_BUILD_ID",
                NT_GNU_GOLD_VERSION => "NT_GNU_GOLD_VERSION",
                NT_GNU_PROPERTY_TYPE_0 => "NT_GNU_PROPERTY_0",
                _ => "NT_UNKNOWN"
            }
        }
    }

    impl<'a> ctx::TryFromCtx<'a, (usize, container::Ctx)> for Note<'a> {
        type Error = error::Error;
        fn try_from_ctx(bytes: &'a [u8], (alignment, ctx): (usize, container::Ctx)) -> Result<(Self, usize), Self::Error> {
            let offset = &mut 0;
            let mut alignment = alignment;
            if alignment < 4 {
                alignment = 4;
            }
            let header: NoteHeader = {
                match alignment {
                    4|8 => bytes.gread_with::<Nhdr32>(offset, ctx.le)?.into(),
                    _ => return Err(error::Error::Malformed(format!("Notes has unimplemented alignment requirement: {:#x}", alignment)))
                }
            };
            debug!("{:?} - {:#x}", header, *offset);
            // -1 because includes \0 terminator
            let name = bytes.gread_with::<&'a str>(offset, ctx::StrCtx::Length(header.n_namesz.saturating_sub(1)))?;
            if header.n_namesz > 0 {
                *offset += 1;
            }
            align(alignment, offset);
            debug!("note name {} - {:#x}", name, *offset);
            let desc = bytes.gread_with::<&'a [u8]>(offset, header.n_descsz)?;
            align(alignment, offset);
            debug!("desc {:?} - {:#x}", desc, *offset);
            Ok((Note {
                name,
                desc,
                n_type: header.n_type,
            }, *offset))
        }
    }

    #[cfg(test)]
    mod tests {
        use super::*;

        static NOTE_DATA: [u8; 132] = [0x04, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00,
                                      0x01, 0x00, 0x00, 0x00, 0x47, 0x4e, 0x55, 0x00,
                                      0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00,
                                      0x06, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00,
                                      0x04, 0x00, 0x00, 0x00, 0x14, 0x00, 0x00, 0x00,
                                      0x03, 0x00, 0x00, 0x00, 0x47, 0x4e, 0x55, 0x00,
                                      0xbc, 0xfc, 0x66, 0xcd, 0xc7, 0xd5, 0x14, 0x7b,
                                      0x53, 0xb1, 0x10, 0x11, 0x94, 0x86, 0x8e, 0xf9,
                                      0x4f, 0xe8, 0xdd, 0xdb, 0x04, 0x00, 0x00, 0x00,
                                      0x30, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00,
                                      0x47, 0x4E, 0x55, 0x00, 0x02, 0x80, 0x00, 0xC0,
                                      0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
                                      0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01, 0xC0,
                                      0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
                                      0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x01, 0xC0,
                                      0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                      0x00, 0x00, 0x00, 0x00];

        static CONTEXT: (usize, container::Ctx) = (4, container::Ctx {
            container: container::Container::Big,
            le: ::scroll::Endian::Little,
        });

        fn make_note_iter(start: usize, end: usize) -> NoteDataIterator<'static> {
            NoteDataIterator {
                data: &NOTE_DATA,
                size: end,
                offset: start,
                ctx: CONTEXT,
            }
        }

        #[test]
        fn iter_single_section() {
            let mut notes = NoteIterator {
                iters: vec![make_note_iter(0, 132)],
                index: 0,
            };

            assert_eq!(notes.next().unwrap().unwrap().n_type, NT_GNU_ABI_TAG);
            assert_eq!(notes.next().unwrap().unwrap().n_type, NT_GNU_BUILD_ID);
            assert_eq!(notes.next().unwrap().unwrap().n_type, NT_GNU_PROPERTY_TYPE_0);
            assert!(notes.next().is_none());
        }

        #[test]
        fn iter_multiple_sections() {
            let mut notes = NoteIterator {
                iters: vec![make_note_iter(0, 32), make_note_iter(32, 68), make_note_iter(68, 132)],
                index: 0,
            };

            assert_eq!(notes.next().unwrap().unwrap().n_type, NT_GNU_ABI_TAG);
            assert_eq!(notes.next().unwrap().unwrap().n_type, NT_GNU_BUILD_ID);
            assert_eq!(notes.next().unwrap().unwrap().n_type, NT_GNU_PROPERTY_TYPE_0);
            assert!(notes.next().is_none());
        }

        #[test]
        fn skip_empty_sections() {
            let mut notes = NoteIterator {
                iters: vec![
                    make_note_iter(0, 32),
                    make_note_iter(0, 0),
                    make_note_iter(32, 68),
                ],
                index: 0,
            };

            assert_eq!(notes.next().unwrap().unwrap().n_type, NT_GNU_ABI_TAG);
            assert_eq!(notes.next().unwrap().unwrap().n_type, NT_GNU_BUILD_ID);
            assert!(notes.next().is_none());
        }

        #[test]
        fn ignore_no_sections() {
            let mut notes = NoteIterator { iters: vec![], index: 0 };
            assert!(notes.next().is_none());
        }
    }
}