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https://git.proxmox.com/git/efi-boot-shim
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3322257e61
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> |
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|---|---|---|
| Cryptlib | ||
| include | ||
| lib | ||
| .gitignore | ||
| cert.S | ||
| COPYRIGHT | ||
| crypt_blowfish.c | ||
| crypt_blowfish.h | ||
| elf_aarch64_efi.lds | ||
| elf_arm_efi.lds | ||
| elf_ia32_efi.lds | ||
| elf_ia64_efi.lds | ||
| elf_x86_64_efi.lds | ||
| fallback.c | ||
| hexdump.h | ||
| make-certs | ||
| Makefile | ||
| MokManager.c | ||
| MokVars.txt | ||
| netboot.c | ||
| netboot.h | ||
| PasswordCrypt.c | ||
| PasswordCrypt.h | ||
| README | ||
| replacements.c | ||
| replacements.h | ||
| shim.c | ||
| shim.h | ||
| testplan.txt | ||
| TODO | ||
| ucs2.h | ||
| version.c.in | ||
| version.h | ||
shim is a trivial EFI application that, when run, attempts to open and execute another application. It will initially attempt to do this via the standard EFI LoadImage() and StartImage() calls. If these fail (because secure boot is enabled and the binary is not signed with an appropriate key, for instance) it will then validate the binary against a built-in certificate. If this succeeds and if the binary or signing key are not blacklisted then shim will relocate and execute the binary. shim will also install a protocol which permits the second-stage bootloader to perform similar binary validation. This protocol has a GUID as described in the shim.h header file and provides a single entry point. On 64-bit systems this entry point expects to be called with SysV ABI rather than MSABI, and so calls to it should not be wrapped. To use shim, simply place a DER-encoded public certificate in a file such as pub.cer and build with "make VENDOR_CERT_FILE=pub.cer".