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shim: handle BDS's li->LoadOptions and Shell's li->LoadOptions .
Load options are a giant pain in the ass, because the shell is a giant piece of junk. If we're invoked from the EFI shell, we get something like this: 00000000 5c 00 45 00 36 00 49 00 5c 00 66 00 65 00 64 00 |\.E.F.I.\.f.e.d.| 00000010 6f 00 72 00 61 00 5c 00 73 00 68 00 69 00 6d 00 |o.r.a.\.s.h.i.m.| 00000020 78 00 36 00 34 00 2e 00 64 00 66 00 69 00 20 00 |x.6.4...e.f.i. .| 00000030 5c 00 45 00 46 00 49 00 5c 00 66 00 65 00 64 00 |\.E.F.I.\.f.e.d.| 00000040 6f 00 72 00 61 00 5c 00 66 00 77 00 75 00 70 00 |o.r.a.\.f.w.u.p.| 00000050 64 00 61 00 74 00 65 00 2e 00 65 00 66 00 20 00 |d.a.t.e.e.f.i. .| 00000060 00 00 66 00 73 00 30 00 3a 00 5c 00 00 00 |..f.s.0.:.\...| which is just some paths rammed together separated by a UCS-2 NUL. But if we're invoked from BDS, we get something more like: 00000000 01 00 00 00 62 00 4c 00 69 00 6e 00 75 00 78 00 |....b.L.i.n.u.x.| 00000010 20 00 46 00 69 00 72 00 6d 00 77 00 61 00 72 00 | .F.i.r.m.w.a.r.| 00000020 65 00 20 00 55 00 70 00 64 00 61 00 74 00 65 00 |e. .U.p.d.a.t.e.| 00000030 72 00 00 00 40 01 2a 00 01 00 00 00 00 08 00 00 |r.....*.........| 00000040 00 00 00 00 00 40 06 00 00 00 00 00 1a 9e 55 bf |.....@........U.| 00000050 04 57 f2 4f b4 4a ed 26 4a 40 6a 94 02 02 04 04 |.W.O.:.&J@j.....| 00000060 34 00 5c 00 45 00 46 00 49 00 5c 00 66 00 65 00 |4.\.E.F.I.f.e.d.| 00000070 64 00 6f 00 72 00 61 00 5c 00 73 00 68 00 69 00 |o.r.a.\.s.h.i.m.| 00000080 6d 00 78 00 36 00 34 00 2e 00 65 00 66 00 69 00 |x.6.4...e.f.i...| 00000090 00 00 7f ff 40 00 20 00 5c 00 66 00 77 00 75 00 |...... .\.f.w.u.| 000000a0 70 00 78 00 36 00 34 00 2e 00 65 00 66 00 69 00 |p.x.6.4...e.f.i.| 000000b0 00 00 |..| which is clearly an EFI_LOAD_OPTION filled in halfway reasonably. In short, the UEFI shell is still a useless piece of junk. So anyway, try to determine which one we've got and handle it appropriately. Signed-off-by: Peter Jones <pjones@redhat.com>
This commit is contained in:
Peter Jones
parent
2a6ebdae2f
commit
3322257e61
270
shim.c
270
shim.c
@ -1951,6 +1951,118 @@ static EFI_STATUS mok_ignore_db()
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}
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EFI_GUID bds_guid = { 0x8108ac4e, 0x9f11, 0x4d59, { 0x85, 0x0e, 0xe2, 0x1a, 0x52, 0x2c, 0x59, 0xb2 } };
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static inline EFI_STATUS
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get_load_option_optional_data(UINT8 *data, UINTN data_size,
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UINT8 **od, UINTN *ods)
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{
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/*
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* If it's not at least Attributes + FilePathListLength +
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* Description=L"" + 0x7fff0400 (EndEntrireDevicePath), it can't
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* be valid.
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*/
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if (data_size < (sizeof(UINT32) + sizeof(UINT16) + 2 + 4))
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return EFI_INVALID_PARAMETER;
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UINT8 *cur = data + sizeof(UINT32);
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UINT16 fplistlen = *(UINT16 *)cur;
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/*
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* If there's not enough space for the file path list and the
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* smallest possible description (L""), it's not valid.
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*/
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if (fplistlen > data_size - (sizeof(UINT32) + 2 + 4))
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return EFI_INVALID_PARAMETER;
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cur += sizeof(UINT16);
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UINTN limit = data_size - (cur - data) - fplistlen;
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UINTN i;
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for (i = 0; i < limit ; i++) {
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/* If the description isn't valid UCS2-LE, it's not valid. */
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if (i % 2 != 0) {
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if (cur[i] != 0)
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return EFI_INVALID_PARAMETER;
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} else if (cur[i] == 0) {
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/* we've found the end */
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i++;
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if (i >= limit || cur[i] != 0)
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return EFI_INVALID_PARAMETER;
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break;
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}
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}
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i++;
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if (i > limit)
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return EFI_INVALID_PARAMETER;
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/*
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* If i is limit, we know the rest of this is the FilePathList and
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* there's no optional data. So just bail now.
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*/
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if (i == limit) {
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*od = NULL;
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*ods = 0;
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return EFI_SUCCESS;
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}
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cur += i;
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limit -= i;
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limit += fplistlen;
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i = 0;
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while (limit - i >= 4) {
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struct {
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UINT8 type;
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UINT8 subtype;
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UINT16 len;
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} dp = {
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.type = cur[i],
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.subtype = cur[i+1],
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/*
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* it's a little endian UINT16, but we're not
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* guaranteed alignment is sane, so we can't just
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* typecast it directly.
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*/
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.len = (cur[i+3] << 8) | cur[i+2],
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};
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/*
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* We haven't found an EndEntire, so this has to be a valid
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* EFI_DEVICE_PATH in order for the data to be valid. That
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* means it has to fit, and it can't be smaller than 4 bytes.
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*/
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if (dp.len < 4 || dp.len > limit)
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return EFI_INVALID_PARAMETER;
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/*
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* see if this is an EndEntire node...
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*/
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if (dp.type == 0x7f && dp.subtype == 0xff) {
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/*
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* if we've found the EndEntire node, it must be 4
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* bytes
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*/
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if (dp.len != 4)
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return EFI_INVALID_PARAMETER;
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i += dp.len;
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break;
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}
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/*
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* It's just some random DP node; skip it.
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*/
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i += dp.len;
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}
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if (i != fplistlen)
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return EFI_INVALID_PARAMETER;
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/*
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* if there's any space left, it's "optional data"
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*/
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*od = cur + i;
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*ods = limit - i;
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return EFI_SUCCESS;
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}
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/*
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* Check the load options to specify the second stage loader
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*/
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@ -1958,11 +2070,11 @@ EFI_STATUS set_second_stage (EFI_HANDLE image_handle)
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{
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EFI_STATUS status;
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EFI_LOADED_IMAGE *li;
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CHAR16 *start = NULL, *c;
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unsigned int i;
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CHAR16 *start = NULL;
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int remaining_size = 0;
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CHAR16 *loader_str = NULL;
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unsigned int loader_len = 0;
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UINTN loader_len = 0;
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unsigned int i;
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second_stage = DEFAULT_LOADER;
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load_options = NULL;
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@ -1975,55 +2087,151 @@ EFI_STATUS set_second_stage (EFI_HANDLE image_handle)
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return status;
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}
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/* Expect a CHAR16 string with at least one CHAR16 */
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if (li->LoadOptionsSize < 4 || li->LoadOptionsSize % 2 != 0) {
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return EFI_BAD_BUFFER_SIZE;
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}
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c = (CHAR16 *)(li->LoadOptions + (li->LoadOptionsSize - 2));
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if (*c != L'\0') {
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/* So, load options are a giant pain in the ass. If we're invoked
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* from the EFI shell, we get something like this:
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00000000 5c 00 45 00 36 00 49 00 5c 00 66 00 65 00 64 00 |\.E.F.I.\.f.e.d.|
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00000010 6f 00 72 00 61 00 5c 00 73 00 68 00 69 00 6d 00 |o.r.a.\.s.h.i.m.|
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00000020 78 00 36 00 34 00 2e 00 64 00 66 00 69 00 20 00 |x.6.4...e.f.i. .|
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00000030 5c 00 45 00 46 00 49 00 5c 00 66 00 65 00 64 00 |\.E.F.I.\.f.e.d.|
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00000040 6f 00 72 00 61 00 5c 00 66 00 77 00 75 00 70 00 |o.r.a.\.f.w.u.p.|
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00000050 64 00 61 00 74 00 65 00 2e 00 65 00 66 00 20 00 |d.a.t.e.e.f.i. .|
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00000060 00 00 66 00 73 00 30 00 3a 00 5c 00 00 00 |..f.s.0.:.\...|
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*
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* which is just some paths rammed together separated by a UCS-2 NUL.
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* But if we're invoked from BDS, we get something more like:
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*
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00000000 01 00 00 00 62 00 4c 00 69 00 6e 00 75 00 78 00 |....b.L.i.n.u.x.|
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00000010 20 00 46 00 69 00 72 00 6d 00 77 00 61 00 72 00 | .F.i.r.m.w.a.r.|
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00000020 65 00 20 00 55 00 70 00 64 00 61 00 74 00 65 00 |e. .U.p.d.a.t.e.|
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00000030 72 00 00 00 40 01 2a 00 01 00 00 00 00 08 00 00 |r.....*.........|
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00000040 00 00 00 00 00 40 06 00 00 00 00 00 1a 9e 55 bf |.....@........U.|
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00000050 04 57 f2 4f b4 4a ed 26 4a 40 6a 94 02 02 04 04 |.W.O.:.&J@j.....|
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00000060 34 00 5c 00 45 00 46 00 49 00 5c 00 66 00 65 00 |4.\.E.F.I.f.e.d.|
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00000070 64 00 6f 00 72 00 61 00 5c 00 73 00 68 00 69 00 |o.r.a.\.s.h.i.m.|
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00000080 6d 00 78 00 36 00 34 00 2e 00 65 00 66 00 69 00 |x.6.4...e.f.i...|
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00000090 00 00 7f ff 40 00 20 00 5c 00 66 00 77 00 75 00 |...... .\.f.w.u.|
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000000a0 70 00 78 00 36 00 34 00 2e 00 65 00 66 00 69 00 |p.x.6.4...e.f.i.|
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000000b0 00 00 |..|
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*
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* which is clearly an EFI_LOAD_OPTION filled in halfway reasonably.
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* In short, the UEFI shell is still a useless piece of junk.
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*/
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/*
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* In either case, we've got to have at least a UCS2 NUL...
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*/
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if (li->LoadOptionsSize < 2)
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return EFI_BAD_BUFFER_SIZE;
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/*
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* Some awesome versions of BDS will add entries for Linux. On top
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* of that, some versions of BDS will "tag" any Boot#### entries they
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* create by putting a GUID at the very end of the optional data in
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* the EFI_LOAD_OPTIONS, thus screwing things up for everybody who
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* tries to actually *use* the optional data for anything. Why they
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* did this instead of adding a flag to the spec to /say/ it's
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* created by BDS, I do not know. For shame.
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*
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* Anyway, just nerf that out from the start. It's always just
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* garbage at the end.
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*/
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if (li->LoadOptionsSize > 16) {
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if (CompareGuid((EFI_GUID *)(li->LoadOptions
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+ (li->LoadOptionsSize - 16)),
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&bds_guid) == 0)
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li->LoadOptionsSize -= 16;
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}
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/*
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* UEFI shell copies the whole line of the command into LoadOptions.
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* We ignore the string before the first L' ', i.e. the name of this
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* program.
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* Check and see if this is just a list of strings. If it's an
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* EFI_LOAD_OPTION, it'll be 0, since we know EndEntire device path
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* won't pass muster as UCS2-LE.
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*
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* If there are 3 strings, we're launched from the shell most likely,
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* But we actually only care about the second one.
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*/
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for (i = 0; i < li->LoadOptionsSize; i += 2) {
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c = (CHAR16 *)(li->LoadOptions + i);
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if (*c == L' ') {
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*c = L'\0';
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start = c + 1;
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remaining_size = li->LoadOptionsSize - i - 2;
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break;
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UINTN strings = count_ucs2_strings(li->LoadOptions,
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li->LoadOptionsSize);
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/*
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* If it's not string data, try it as an EFI_LOAD_OPTION.
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*/
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if (strings == 0) {
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/*
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* We at least didn't find /enough/ strings. See if it works
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* as an EFI_LOAD_OPTION.
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*/
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status = get_load_option_optional_data(li->LoadOptions,
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li->LoadOptionsSize,
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(UINT8 **)&start,
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&loader_len);
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if (status != EFI_SUCCESS)
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return EFI_SUCCESS;
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remaining_size = 0;
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} else if (strings >= 2) {
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/*
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* UEFI shell copies the whole line of the command into
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* LoadOptions. We ignore the string before the first L' ',
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* i.e. the name of this program.
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* Counting by two bytes is safe, because we know the size is
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* compatible with a UCS2-LE string.
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*/
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UINT8 *cur = li->LoadOptions;
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for (i = 0; i < li->LoadOptionsSize - 2; i += 2) {
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CHAR16 c = (cur[i+1] << 8) | cur[i];
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if (c == L' ') {
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start = (CHAR16 *)&cur[i+2];
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remaining_size = li->LoadOptionsSize - i - 2;
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break;
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}
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}
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if (!start || remaining_size <= 0 || start[0] == L'\0')
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return EFI_SUCCESS;
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for (i = 0; start[i] != '\0'; i++) {
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if (start[i] == L' ')
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start[i] = L'\0';
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if (start[i] == L'\0') {
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loader_len = 2 * i + 2;
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break;
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}
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}
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if (loader_len)
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remaining_size -= loader_len;
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}
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if (!start || remaining_size <= 0)
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/*
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* Just to be sure all that math is right...
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*/
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if (loader_len % 2 != 0)
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return EFI_INVALID_PARAMETER;
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strings = count_ucs2_strings((UINT8 *)start, loader_len);
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if (strings < 1)
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return EFI_SUCCESS;
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for (i = 0; start[i] != '\0'; i++) {
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if (start[i] == L' ' || start[i] == L'\0')
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break;
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loader_len++;
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}
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/*
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* Setup the name of the alternative loader and the LoadOptions for
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* Set up the name of the alternative loader and the LoadOptions for
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* the loader
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*/
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if (loader_len > 0) {
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loader_str = AllocatePool((loader_len + 1) * sizeof(CHAR16));
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loader_str = AllocatePool(loader_len);
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if (!loader_str) {
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perror(L"Failed to allocate loader string\n");
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return EFI_OUT_OF_RESOURCES;
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}
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for (i = 0; i < loader_len; i++)
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for (i = 0; i < loader_len / 2; i++)
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loader_str[i] = start[i];
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loader_str[loader_len] = L'\0';
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loader_str[loader_len/2-1] = L'\0';
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second_stage = loader_str;
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load_options = start;
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load_options = remaining_size ? start + loader_len : NULL;
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load_options_size = remaining_size;
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}
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29
ucs2.h
29
ucs2.h
@ -89,4 +89,33 @@ StrCSpn(const CHAR16 *s, const CHAR16 *reject)
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return ret;
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}
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static inline UINTN
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__attribute__((__unused__))
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count_ucs2_strings(UINT8 *data, UINTN data_size)
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{
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UINTN pos = 0;
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UINTN last_nul_pos = 0;
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UINTN num_nuls = 0;
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UINTN i;
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if (data_size % 2 != 0)
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return 0;
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for (i = pos; i < data_size; i++) {
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if (i % 2 != 0) {
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if (data[i] != 0)
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return 0;
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} else if (data[i] == 0) {
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if (i+1 >= data_size || data[i+1] != 0)
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return 0;
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last_nul_pos = i;
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num_nuls++;
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}
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pos = i;
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}
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if (num_nuls > 0 && last_nul_pos != pos - 1)
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return 0;
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return num_nuls;
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}
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#endif /* SHIM_UCS2_H */
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