MIPS Payload updates

[dledda-r7]

MIPS64 exec payload, mipsle and mipsbe exec payload update, and prepends for everybody.

[Copilot]

Pull request overview

This PR updates Metasploit’s Linux MIPS payload set by introducing a new linux/mips64/exec single payload, modernizing the existing mipsle/mipsbe exec payloads (including prepend support), and correcting MIPS64 ELF generation/template metadata to better match expected endianness and header values.

Changes:

• Add a new linux/mips64/exec single payload and a corresponding cached-size spec.
• Update mipsle/mipsbe exec payloads to support prepend stubs and to run /bin/sh when CMD is unset.
• Enable Linux prepend stubs (set*uid) for MIPS LE/BE/MIPS64 and adjust MIPS64 ELF generation/template header values.

Impact Analysis:

• Blast radius: medium; affects users generating Linux MIPS64 executables (EXE generation) and users selecting linux/mips{le,be,mips64}/exec payloads; downstream impact Unknown.
• Data and contract effects: payload behavior changes when CMD is unset (now spawns /bin/sh for mipsle/mipsbe/mips64 exec); MIPS64 ELF template/header interpretation changes via endianness handling.
• Rollback and test focus: rollback is straightforward (revert payload/template/util changes); focus testing on generated MIPS64 ELF validity/executability and verifying exec payload behavior for both empty CMD and non-empty CMD, with/without prepend options.

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
spec/modules/payloads_spec.rb	Adds cached-size consistency coverage for the new linux/mips64/exec payload.
modules/payloads/singles/linux/mipsle/exec.rb	Updates MIPSLE exec payload to spawn /bin/sh when CMD is empty and adds prepend support.
modules/payloads/singles/linux/mipsbe/exec.rb	Updates MIPSBE exec payload to spawn /bin/sh when CMD is empty and adds prepend support.
modules/payloads/singles/linux/mips64/exec.rb	Introduces a new MIPS64 exec payload supporting /bin/sh and -c CMD forms with prepends.
lib/msf/util/exe/linux/mips64.rb	Adjusts MIPS64 ELF generation to pass big-endian handling into the common ELF builder.
lib/msf/core/payload/linux/mipsle/prepends.rb	Enables set*uid prepend options and provides MIPSLE syscall stubs.
lib/msf/core/payload/linux/mipsbe/prepends.rb	Enables set*uid prepend options and provides MIPSBE syscall stubs.
lib/msf/core/payload/linux/mips64/prepends.rb	Enables set*uid prepend options and provides MIPS64 syscall stubs.
data/templates/src/elf/exe/elf_mips64_template.s	Updates MIPS64 ELF header fields (version/flags) in the source template.