July 2025 - Linux-kselftest-mirror

[PATCH RFC 0/4] landlock: add LANDLOCK_SCOPE_MEMFD_EXEC execution

by Abhinav Saxena

This patch series introduces LANDLOCK_SCOPE_MEMFD_EXEC, a new Landlock scoping mechanism that restricts execution of anonymous memory file descriptors (memfd) created via memfd_create(2). This addresses security gaps where processes can bypass W^X policies and execute arbitrary code through anonymous memory objects. Fixes: https://github.com/landlock-lsm/linux/issues/37 SECURITY PROBLEM ================ Current Landlock filesystem restrictions do not cover memfd objects, allowing processes to: 1. Read-to-execute bypass: Create writable memfd, inject code, then execute via mmap(PROT_EXEC) or direct execve() 2. Anonymous execution: Execute code without touching the filesystem via execve("/proc/self/fd/N") where N is a memfd descriptor 3. Cross-domain access violations: Pass memfd between processes to bypass domain restrictions These scenarios can occur in sandboxed environments where filesystem access is restricted but memfd creation remains possible. IMPLEMENTATION ============== The implementation adds hierarchical execution control through domain scoping: Core Components: - is_memfd_file(): Reliable memfd detection via "memfd:" dentry prefix - domain_is_scoped(): Cross-domain hierarchy checking (moved to domain.c) - LSM hooks: mmap_file, file_mprotect, bprm_creds_for_exec - Creation-time restrictions: hook_file_alloc_security Security Matrix: Execution decisions follow domain hierarchy rules preventing both same-domain bypass attempts and cross-domain access violations while preserving legitimate hierarchical access patterns. Domain Hierarchy with LANDLOCK_SCOPE_MEMFD_EXEC: =============================================== Root (no domain) - No restrictions | +-- Domain A [SCOPE_MEMFD_EXEC] Layer 1 | +-- memfd_A (tagged with Domain A as creator) | | | +-- Domain A1 (child) [NO SCOPE] Layer 2 | | +-- Inherits Layer 1 restrictions from parent | | +-- memfd_A1 (can create, inherits restrictions) | | +-- Domain A1a [SCOPE_MEMFD_EXEC] Layer 3 | | +-- memfd_A1a (tagged with Domain A1a) | | | +-- Domain A2 (child) [SCOPE_MEMFD_EXEC] Layer 2 | +-- memfd_A2 (tagged with Domain A2 as creator) | +-- CANNOT access memfd_A1 (different subtree) | +-- Domain B [SCOPE_MEMFD_EXEC] Layer 1 +-- memfd_B (tagged with Domain B as creator) +-- CANNOT access ANY memfd from Domain A subtree Execution Decision Matrix: ======================== Executor-> | A | A1 | A1a | A2 | B | Root Creator | | | | | | ------------|-----|----|-----|----|----|----- Domain A | X | X | X | X | X | Y Domain A1 | Y | X | X | X | X | Y Domain A1a | Y | Y | X | X | X | Y Domain A2 | Y | X | X | X | X | Y Domain B | X | X | X | X | X | Y Root | Y | Y | Y | Y | Y | Y Legend: Y = Execution allowed, X = Execution denied Scenarios Covered: - Direct mmap(PROT_EXEC) on memfd files - Two-stage mmap(PROT_READ) + mprotect(PROT_EXEC) bypass attempts - execve("/proc/self/fd/N") anonymous execution - execveat() and fexecve() file descriptor execution - Cross-process memfd inheritance and IPC passing TESTING ======= All patches have been validated with: - scripts/checkpatch.pl --strict (clean) - Selftests covering same-domain restrictions, cross-domain hierarchy enforcement, and regular file isolation - KUnit tests for memfd detection edge cases DISCLAIMER ========== My understanding of Landlock scoping semantics may be limited, but this implementation reflects my current understanding based on available documentation and code analysis. I welcome feedback and corrections regarding the scoping logic and domain hierarchy enforcement. Signed-off-by: Abhinav Saxena <xandfury(a)gmail.com> --- Abhinav Saxena (4): landlock: add LANDLOCK_SCOPE_MEMFD_EXEC scope landlock: implement memfd detection landlock: add memfd exec LSM hooks and scoping selftests/landlock: add memfd execution tests include/uapi/linux/landlock.h | 5 + security/landlock/.kunitconfig | 1 + security/landlock/audit.c | 4 + security/landlock/audit.h | 1 + security/landlock/cred.c | 14 - security/landlock/domain.c | 67 ++++ security/landlock/domain.h | 4 + security/landlock/fs.c | 405 ++++++++++++++++++++- security/landlock/limits.h | 2 +- security/landlock/task.c | 67 ---- .../selftests/landlock/scoped_memfd_exec_test.c | 325 +++++++++++++++++ 11 files changed, 812 insertions(+), 83 deletions(-) --- base-commit: 5b74b2eff1eeefe43584e5b7b348c8cd3b723d38 change-id: 20250716-memfd-exec-ac0d582018c3 Best regards, -- Abhinav Saxena <xandfury(a)gmail.com>

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[PATCH v19 00/27] riscv control-flow integrity for usermode

by Deepak Gupta

Basics and overview =================== Software with larger attack surfaces (e.g. network facing apps like databases, browsers or apps relying on browser runtimes) suffer from memory corruption issues which can be utilized by attackers to bend control flow of the program to eventually gain control (by making their payload executable). Attackers are able to perform such attacks by leveraging call-sites which rely on indirect calls or return sites which rely on obtaining return address from stack memory. To mitigate such attacks, risc-v extension zicfilp enforces that all indirect calls must land on a landing pad instruction `lpad` else cpu will raise software check exception (a new cpu exception cause code on riscv). Similarly for return flow, risc-v extension zicfiss extends architecture with - `sspush` instruction to push return address on a shadow stack - `sspopchk` instruction to pop return address from shadow stack and compare with input operand (i.e. return address on stack) - `sspopchk` to raise software check exception if comparision above was a mismatch - Protection mechanism using which shadow stack is not writeable via regular store instructions More information an details can be found at extensions github repo [1]. Equivalent to landing pad (zicfilp) on x86 is `ENDBRANCH` instruction in Intel CET [3] and branch target identification (BTI) [4] on arm. Similarly x86's Intel CET has shadow stack [5] and arm64 has guarded control stack (GCS) [6] which are very similar to risc-v's zicfiss shadow stack. x86 and arm64 support for user mode shadow stack is already in mainline. Kernel awareness for user control flow integrity ================================================ This series picks up Samuel Holland's envcfg changes [2] as well. So if those are being applied independently, they should be removed from this series. Enabling: In order to maintain compatibility and not break anything in user mode, kernel doesn't enable control flow integrity cpu extensions on binary by default. Instead exposes a prctl interface to enable, disable and lock the shadow stack or landing pad feature for a task. This allows userspace (loader) to enumerate if all objects in its address space are compiled with shadow stack and landing pad support and accordingly enable the feature. Additionally if a subsequent `dlopen` happens on a library, user mode can take a decision again to disable the feature (if incoming library is not compiled with support) OR terminate the task (if user mode policy is strict to have all objects in address space to be compiled with control flow integirty cpu feature). prctl to enable shadow stack results in allocating shadow stack from virtual memory and activating for user address space. x86 and arm64 are also following same direction due to similar reason(s). clone/fork: On clone and fork, cfi state for task is inherited by child. Shadow stack is part of virtual memory and is a writeable memory from kernel perspective (writeable via a restricted set of instructions aka shadow stack instructions) Thus kernel changes ensure that this memory is converted into read-only when fork/clone happens and COWed when fault is taken due to sspush, sspopchk or ssamoswap. In case `CLONE_VM` is specified and shadow stack is to be enabled, kernel will automatically allocate a shadow stack for that clone call. map_shadow_stack: x86 introduced `map_shadow_stack` system call to allow user space to explicitly map shadow stack memory in its address space. It is useful to allocate shadow for different contexts managed by a single thread (green threads or contexts) risc-v implements this system call as well. signal management: If shadow stack is enabled for a task, kernel performs an asynchronous control flow diversion to deliver the signal and eventually expects userspace to issue sigreturn so that original execution can be resumed. Even though resume context is prepared by kernel, it is in user space memory and is subject to memory corruption and corruption bugs can be utilized by attacker in this race window to perform arbitrary sigreturn and eventually bypass cfi mechanism. Another issue is how to ensure that cfi related state on sigcontext area is not trampled by legacy apps or apps compiled with old kernel headers. In order to mitigate control-flow hijacting, kernel prepares a token and place it on shadow stack before signal delivery and places address of token in sigcontext structure. During sigreturn, kernel obtains address of token from sigcontext struture, reads token from shadow stack and validates it and only then allow sigreturn to succeed. Compatiblity issue is solved by adopting dynamic sigcontext management introduced for vector extension. This series re-factor the code little bit to allow future sigcontext management easy (as proposed by Andy Chiu from SiFive) config and compilation: Introduce a new risc-v config option `CONFIG_RISCV_USER_CFI`. Selecting this config option picks the kernel support for user control flow integrity. This optin is presented only if toolchain has shadow stack and landing pad support. And is on purpose guarded by toolchain support. Reason being that eventually vDSO also needs to be compiled in with shadow stack and landing pad support. vDSO compile patches are not included as of now because landing pad labeling scheme is yet to settle for usermode runtime. To get more information on kernel interactions with respect to zicfilp and zicfiss, patch series adds documentation for `zicfilp` and `zicfiss` in following: Documentation/arch/riscv/zicfiss.rst Documentation/arch/riscv/zicfilp.rst How to test this series ======================= Toolchain --------- $ git clone git@github.com:sifive/riscv-gnu-toolchain.git -b cfi-dev $ riscv-gnu-toolchain/configure --prefix=<path-to-where-to-build> --with-arch=rv64gc_zicfilp_zicfiss --enable-linux --disable-gdb --with-extra-multilib-test="rv64gc_zicfilp_zicfiss-lp64d:-static" $ make -j$(nproc) Qemu ---- Get the lastest qemu $ cd qemu $ mkdir build $ cd build $ ../configure --target-list=riscv64-softmmu $ make -j$(nproc) Opensbi ------- $ git clone git@github.com:deepak0414/opensbi.git -b v6_cfi_spec_split_opensbi $ make CROSS_COMPILE=<your riscv toolchain> -j$(nproc) PLATFORM=generic Linux ----- Running defconfig is fine. CFI is enabled by default if the toolchain supports it. $ make ARCH=riscv CROSS_COMPILE=<path-to-cfi-riscv-gnu-toolchain>/build/bin/riscv64-unknown-linux-gnu- -j$(nproc) defconfig $ make ARCH=riscv CROSS_COMPILE=<path-to-cfi-riscv-gnu-toolchain>/build/bin/riscv64-unknown-linux-gnu- -j$(nproc) In case you're building your own rootfs using toolchain, please make sure you pick following patch to ensure that vDSO compiled with lpad and shadow stack. "arch/riscv: compile vdso with landing pad" Branch where above patch can be picked https://github.com/deepak0414/linux-riscv-cfi/tree/vdso_user_cfi_v6.12-rc1 Running ------- Modify your qemu command to have: -bios <path-to-cfi-opensbi>/build/platform/generic/firmware/fw_dynamic.bin -cpu rv64,zicfilp=true,zicfiss=true,zimop=true,zcmop=true vDSO related Opens (in the flux) ================================= I am listing these opens for laying out plan and what to expect in future patch sets. And of course for the sake of discussion. Shadow stack and landing pad enabling in vDSO ---------------------------------------------- vDSO must have shadow stack and landing pad support compiled in for task to have shadow stack and landing pad support. This patch series doesn't enable that (yet). Enabling shadow stack support in vDSO should be straight forward (intend to do that in next versions of patch set). Enabling landing pad support in vDSO requires some collaboration with toolchain folks to follow a single label scheme for all object binaries. This is necessary to ensure that all indirect call-sites are setting correct label and target landing pads are decorated with same label scheme. How many vDSOs --------------- Shadow stack instructions are carved out of zimop (may be operations) and if CPU doesn't implement zimop, they're illegal instructions. Kernel could be running on a CPU which may or may not implement zimop. And thus kernel will have to carry 2 different vDSOs and expose the appropriate one depending on whether CPU implements zimop or not. References ========== [1] - https://github.com/riscv/riscv-cfi [2] - https://lore.kernel.org/all/20240814081126.956287-1-samuel.holland@sifive.c… [3] - https://lwn.net/Articles/889475/ [4] - https://developer.arm.com/documentation/109576/0100/Branch-Target-Identific… [5] - https://www.intel.com/content/dam/develop/external/us/en/documents/catc17-i… [6] - https://lwn.net/Articles/940403/ To: Thomas Gleixner <tglx(a)linutronix.de> To: Ingo Molnar <mingo(a)redhat.com> To: Borislav Petkov <bp(a)alien8.de> To: Dave Hansen <dave.hansen(a)linux.intel.com> To: x86(a)kernel.org To: H. Peter Anvin <hpa(a)zytor.com> To: Andrew Morton <akpm(a)linux-foundation.org> To: Liam R. Howlett <Liam.Howlett(a)oracle.com> To: Vlastimil Babka <vbabka(a)suse.cz> To: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> To: Paul Walmsley <paul.walmsley(a)sifive.com> To: Palmer Dabbelt <palmer(a)dabbelt.com> To: Albert Ou <aou(a)eecs.berkeley.edu> To: Conor Dooley <conor(a)kernel.org> To: Rob Herring <robh(a)kernel.org> To: Krzysztof Kozlowski <krzk+dt(a)kernel.org> To: Arnd Bergmann <arnd(a)arndb.de> To: Christian Brauner <brauner(a)kernel.org> To: Peter Zijlstra <peterz(a)infradead.org> To: Oleg Nesterov <oleg(a)redhat.com> To: Eric Biederman <ebiederm(a)xmission.com> To: Kees Cook <kees(a)kernel.org> To: Jonathan Corbet <corbet(a)lwn.net> To: Shuah Khan <shuah(a)kernel.org> To: Jann Horn <jannh(a)google.com> To: Conor Dooley <conor+dt(a)kernel.org> To: Miguel Ojeda <ojeda(a)kernel.org> To: Alex Gaynor <alex.gaynor(a)gmail.com> To: Boqun Feng <boqun.feng(a)gmail.com> To: Gary Guo <gary(a)garyguo.net> To: Björn Roy Baron <bjorn3_gh(a)protonmail.com> To: Benno Lossin <benno.lossin(a)proton.me> To: Andreas Hindborg <a.hindborg(a)kernel.org> To: Alice Ryhl <aliceryhl(a)google.com> To: Trevor Gross <tmgross(a)umich.edu> Cc: linux-kernel(a)vger.kernel.org Cc: linux-fsdevel(a)vger.kernel.org Cc: linux-mm(a)kvack.org Cc: linux-riscv(a)lists.infradead.org Cc: devicetree(a)vger.kernel.org Cc: linux-arch(a)vger.kernel.org Cc: linux-doc(a)vger.kernel.org Cc: linux-kselftest(a)vger.kernel.org Cc: alistair.francis(a)wdc.com Cc: richard.henderson(a)linaro.org Cc: jim.shu(a)sifive.com Cc: andybnac(a)gmail.com Cc: kito.cheng(a)sifive.com Cc: charlie(a)rivosinc.com Cc: atishp(a)rivosinc.com Cc: evan(a)rivosinc.com Cc: cleger(a)rivosinc.com Cc: alexghiti(a)rivosinc.com Cc: samitolvanen(a)google.com Cc: broonie(a)kernel.org Cc: rick.p.edgecombe(a)intel.com Cc: rust-for-linux(a)vger.kernel.org changelog --------- v19: - riscv_nousercfi was `int`. changed it to unsigned long. Thanks to Alex Ghiti for reporting it. It was a bug. - ELP is cleared on trap entry only when CONFIG_64BIT. - restore ssp back on return to usermode was being done before `riscv_v_context_nesting_end` on trap exit path. If kernel shadow stack were enabled this would result in kernel operating on user shadow stack and panic (as I found in my testing of kcfi patch series). So fixed that. v18: - rebased on 6.16-rc1 - uprobe handling clears ELP in sstatus image in pt_regs - vdso was missing shadow stack elf note for object files. added that. Additional asm file for vdso needed the elf marker flag. toolchain should complain if `-fcf-protection=full` and marker is missing for object generated from asm file. Asked toolchain folks to fix this. Although no reason to gate the merge on that. - Split up compile options for march and fcf-protection in vdso Makefile - CONFIG_RISCV_USER_CFI option is moved under "Kernel features" menu Added `arch/riscv/configs/hardening.config` fragment which selects CONFIG_RISCV_USER_CFI v17: - fixed warnings due to empty macros in usercfi.h (reported by alexg) - fixed prefixes in commit titles reported by alexg - took below uprobe with fcfi v2 patch from Zong Li and squashed it with "riscv/traps: Introduce software check exception and uprobe handling" https://lore.kernel.org/all/20250604093403.10916-1-zong.li@sifive.com/ v16: - If FWFT is not implemented or returns error for shadow stack activation, then no_usercfi is set to disable shadow stack. Although this should be picked up by extension validation and activation. Fixed this bug for zicfilp and zicfiss both. Thanks to Charlie Jenkins for reporting this. - If toolchain doesn't support cfi, cfi kselftest shouldn't build. Suggested by Charlie Jenkins. - Default for CONFIG_RISCV_USER_CFI is set to no. Charlie/Atish suggested to keep it off till we have more hardware availibility with RVA23 profile and zimop/zcmop implemented. Else this will start breaking people's workflow - Includes the fix if "!RV64 and !SBI" then definitions for FWFT in asm-offsets.c error. v15: - Toolchain has been updated to include `-fcf-protection` flag. This exists for x86 as well. Updated kernel patches to compile vDSO and selftest to compile with `fcf-protection=full` flag. - selecting CONFIG_RISCV_USERCFI selects CONFIG_RISCV_SBI. - Patch to enable shadow stack for kernel wasn't hidden behind CONFIG_RISCV_USERCFI and CONFIG_RISCV_SBI. fixed that. v14: - rebased on top of palmer/sbi-v3. Thus dropped clement's FWFT patches Updated RISCV_ISA_EXT_XXXX in hwcap and hwprobe constants. - Took Radim's suggestions on bitfields. - Placed cfi_state at the end of thread_info block so that current situation is not disturbed with respect to member fields of thread_info in single cacheline. v13: - cpu_supports_shadow_stack/cpu_supports_indirect_br_lp_instr uses riscv_has_extension_unlikely() - uses nops(count) to create nop slide - RISCV_ACQUIRE_BARRIER is not needed in `amo_user_shstk`. Removed it - changed ternaries to simply use implicit casting to convert to bool. - kernel command line allows to disable zicfilp and zicfiss independently. updated kernel-parameters.txt. - ptrace user abi for cfi uses bitmasks instead of bitfields. Added ptrace kselftest. - cosmetic and grammatical changes to documentation. v12: - It seems like I had accidently squashed arch agnostic indirect branch tracking prctl and riscv implementation of those prctls. Split them again. - set_shstk_status/set_indir_lp_status perform CSR writes only when CPU support is available. As suggested by Zong Li. - Some minor clean up in kselftests as suggested by Zong Li. v11: - patch "arch/riscv: compile vdso with landing pad" was unconditionally selecting `_zicfilp` for vDSO compile. fixed that. Changed `lpad 1` to to `lpad 0`. v10: - dropped "mm: helper `is_shadow_stack_vma` to check shadow stack vma". This patch is not that interesting to this patch series for risc-v. There are instances in arch directories where VM_SHADOW_STACK flag is anyways used. Dropping this patch to expedite merging in riscv tree. - Took suggestions from `Clement` on "riscv: zicfiss / zicfilp enumeration" to validate presence of cfi based on config. - Added a patch for vDSO to have `lpad 0`. I had omitted this earlier to make sure we add single vdso object with cfi enabled. But a vdso object with scheme of zero labeled landing pad is least common denominator and should work with all objects of zero labeled as well as function-signature labeled objects. v9: - rebased on master (39a803b754d5 fix braino in "9p: fix ->rename_sem exclusion") - dropped "mm: Introduce ARCH_HAS_USER_SHADOW_STACK" (master has it from arm64/gcs) - dropped "prctl: arch-agnostic prctl for shadow stack" (master has it from arm64/gcs) v8: - rebased on palmer/for-next - dropped samuel holland's `envcfg` context switch patches. they are in parlmer/for-next v7: - Removed "riscv/Kconfig: enable HAVE_EXIT_THREAD for riscv" Instead using `deactivate_mm` flow to clean up. see here for more context https://lore.kernel.org/all/20230908203655.543765-1-rick.p.edgecombe@intel.… - Changed the header include in `kselftest`. Hopefully this fixes compile issue faced by Zong Li at SiFive. - Cleaned up an orphaned change to `mm/mmap.c` in below patch "riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE" - Lock interfaces for shadow stack and indirect branch tracking expect arg == 0 Any future evolution of this interface should accordingly define how arg should be setup. - `mm/map.c` has an instance of using `VM_SHADOW_STACK`. Fixed it to use helper `is_shadow_stack_vma`. - Link to v6: https://lore.kernel.org/r/20241008-v5_user_cfi_series-v6-0-60d9fe073f37@riv… v6: - Picked up Samuel Holland's changes as is with `envcfg` placed in `thread` instead of `thread_info` - fixed unaligned newline escapes in kselftest - cleaned up messages in kselftest and included test output in commit message - fixed a bug in clone path reported by Zong Li - fixed a build issue if CONFIG_RISCV_ISA_V is not selected (this was introduced due to re-factoring signal context management code) v5: - rebased on v6.12-rc1 - Fixed schema related issues in device tree file - Fixed some of the documentation related issues in zicfilp/ss.rst (style issues and added index) - added `SHADOW_STACK_SET_MARKER` so that implementation can define base of shadow stack. - Fixed warnings on definitions added in usercfi.h when CONFIG_RISCV_USER_CFI is not selected. - Adopted context header based signal handling as proposed by Andy Chiu - Added support for enabling kernel mode access to shadow stack using FWFT (https://github.com/riscv-non-isa/riscv-sbi-doc/blob/master/src/ext-firmware…) - Link to v5: https://lore.kernel.org/r/20241001-v5_user_cfi_series-v1-0-3ba65b6e550f@riv… (Note: I had an issue in my workflow due to which version number wasn't picked up correctly while sending out patches) v4: - rebased on 6.11-rc6 - envcfg: Converged with Samuel Holland's patches for envcfg management on per- thread basis. - vma_is_shadow_stack is renamed to is_vma_shadow_stack - picked up Mark Brown's `ARCH_HAS_USER_SHADOW_STACK` patch - signal context: using extended context management to maintain compatibility. - fixed `-Wmissing-prototypes` compiler warnings for prctl functions - Documentation fixes and amending typos. - Link to v4: https://lore.kernel.org/all/20240912231650.3740732-1-debug@rivosinc.com/ v3: - envcfg logic to pick up base envcfg had a bug where `ENVCFG_CBZE` could have been picked on per task basis, even though CPU didn't implement it. Fixed in this series. - dt-bindings As suggested, split into separate commit. fixed the messaging that spec is in public review - arch_is_shadow_stack change arch_is_shadow_stack changed to vma_is_shadow_stack - hwprobe zicfiss / zicfilp if present will get enumerated in hwprobe - selftests As suggested, added object and binary filenames to .gitignore Selftest binary anyways need to be compiled with cfi enabled compiler which will make sure that landing pad and shadow stack are enabled. Thus removed separate enable/disable tests. Cleaned up tests a bit. - Link to v3: https://lore.kernel.org/lkml/20240403234054.2020347-1-debug@rivosinc.com/ v2: - Using config `CONFIG_RISCV_USER_CFI`, kernel support for riscv control flow integrity for user mode programs can be compiled in the kernel. - Enabling of control flow integrity for user programs is left to user runtime - This patch series introduces arch agnostic `prctls` to enable shadow stack and indirect branch tracking. And implements them on riscv. --- Changes in v19: - Link to v18: https://lore.kernel.org/r/20250711-v5_user_cfi_series-v18-0-a8ee62f9f38e@ri… Changes in v18: - Link to v17: https://lore.kernel.org/r/20250604-v5_user_cfi_series-v17-0-4565c2cf869f@ri… Changes in v17: - Link to v16: https://lore.kernel.org/r/20250522-v5_user_cfi_series-v16-0-64f61a35eee7@ri… Changes in v16: - Link to v15: https://lore.kernel.org/r/20250502-v5_user_cfi_series-v15-0-914966471885@ri… Changes in v15: - changelog posted just below cover letter - Link to v14: https://lore.kernel.org/r/20250429-v5_user_cfi_series-v14-0-5239410d012a@ri… Changes in v14: - changelog posted just below cover letter - Link to v13: https://lore.kernel.org/r/20250424-v5_user_cfi_series-v13-0-971437de586a@ri… Changes in v13: - changelog posted just below cover letter - Link to v12: https://lore.kernel.org/r/20250314-v5_user_cfi_series-v12-0-e51202b53138@ri… Changes in v12: - changelog posted just below cover letter - Link to v11: https://lore.kernel.org/r/20250310-v5_user_cfi_series-v11-0-86b36cbfb910@ri… Changes in v11: - changelog posted just below cover letter - Link to v10: https://lore.kernel.org/r/20250210-v5_user_cfi_series-v10-0-163dcfa31c60@ri… --- Andy Chiu (1): riscv: signal: abstract header saving for setup_sigcontext Deepak Gupta (25): mm: VM_SHADOW_STACK definition for riscv dt-bindings: riscv: zicfilp and zicfiss in dt-bindings (extensions.yaml) riscv: zicfiss / zicfilp enumeration riscv: zicfiss / zicfilp extension csr and bit definitions riscv: usercfi state for task and save/restore of CSR_SSP on trap entry/exit riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE riscv/mm: manufacture shadow stack pte riscv/mm: teach pte_mkwrite to manufacture shadow stack PTEs riscv/mm: write protect and shadow stack riscv/mm: Implement map_shadow_stack() syscall riscv/shstk: If needed allocate a new shadow stack on clone riscv: Implements arch agnostic shadow stack prctls prctl: arch-agnostic prctl for indirect branch tracking riscv: Implements arch agnostic indirect branch tracking prctls riscv/traps: Introduce software check exception and uprobe handling riscv/signal: save and restore of shadow stack for signal riscv/kernel: update __show_regs to print shadow stack register riscv/ptrace: riscv cfi status and state via ptrace and in core files riscv/hwprobe: zicfilp / zicfiss enumeration in hwprobe riscv: kernel command line option to opt out of user cfi riscv: enable kernel access to shadow stack memory via FWFT sbi call riscv: create a config for shadow stack and landing pad instr support riscv: Documentation for landing pad / indirect branch tracking riscv: Documentation for shadow stack on riscv kselftest/riscv: kselftest for user mode cfi Jim Shu (1): arch/riscv: compile vdso with landing pad and shadow stack note Documentation/admin-guide/kernel-parameters.txt | 8 + Documentation/arch/riscv/index.rst | 2 + Documentation/arch/riscv/zicfilp.rst | 115 +++++ Documentation/arch/riscv/zicfiss.rst | 179 +++++++ .../devicetree/bindings/riscv/extensions.yaml | 14 + arch/riscv/Kconfig | 21 + arch/riscv/Makefile | 5 +- arch/riscv/configs/hardening.config | 4 + arch/riscv/include/asm/asm-prototypes.h | 1 + arch/riscv/include/asm/assembler.h | 44 ++ arch/riscv/include/asm/cpufeature.h | 12 + arch/riscv/include/asm/csr.h | 16 + arch/riscv/include/asm/entry-common.h | 2 + arch/riscv/include/asm/hwcap.h | 2 + arch/riscv/include/asm/mman.h | 26 + arch/riscv/include/asm/mmu_context.h | 7 + arch/riscv/include/asm/pgtable.h | 30 +- arch/riscv/include/asm/processor.h | 1 + arch/riscv/include/asm/thread_info.h | 3 + arch/riscv/include/asm/usercfi.h | 95 ++++ arch/riscv/include/asm/vector.h | 3 + arch/riscv/include/uapi/asm/hwprobe.h | 2 + arch/riscv/include/uapi/asm/ptrace.h | 34 ++ arch/riscv/include/uapi/asm/sigcontext.h | 1 + arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/asm-offsets.c | 10 + arch/riscv/kernel/cpufeature.c | 27 + arch/riscv/kernel/entry.S | 38 ++ arch/riscv/kernel/head.S | 27 + arch/riscv/kernel/process.c | 27 +- arch/riscv/kernel/ptrace.c | 95 ++++ arch/riscv/kernel/signal.c | 148 +++++- arch/riscv/kernel/sys_hwprobe.c | 2 + arch/riscv/kernel/sys_riscv.c | 10 + arch/riscv/kernel/traps.c | 54 ++ arch/riscv/kernel/usercfi.c | 545 +++++++++++++++++++++ arch/riscv/kernel/vdso/Makefile | 11 +- arch/riscv/kernel/vdso/flush_icache.S | 4 + arch/riscv/kernel/vdso/getcpu.S | 4 + arch/riscv/kernel/vdso/rt_sigreturn.S | 4 + arch/riscv/kernel/vdso/sys_hwprobe.S | 4 + arch/riscv/kernel/vdso/vgetrandom-chacha.S | 5 +- arch/riscv/mm/init.c | 2 +- arch/riscv/mm/pgtable.c | 16 + include/linux/cpu.h | 4 + include/linux/mm.h | 7 + include/uapi/linux/elf.h | 2 + include/uapi/linux/prctl.h | 27 + kernel/sys.c | 30 ++ tools/testing/selftests/riscv/Makefile | 2 +- tools/testing/selftests/riscv/cfi/.gitignore | 3 + tools/testing/selftests/riscv/cfi/Makefile | 16 + tools/testing/selftests/riscv/cfi/cfi_rv_test.h | 82 ++++ tools/testing/selftests/riscv/cfi/riscv_cfi_test.c | 173 +++++++ tools/testing/selftests/riscv/cfi/shadowstack.c | 385 +++++++++++++++ tools/testing/selftests/riscv/cfi/shadowstack.h | 27 + 56 files changed, 2389 insertions(+), 30 deletions(-) --- base-commit: a2a05801de77ca5122fc34e3eb84d6359ef70389 change-id: 20240930-v5_user_cfi_series-3dc332f8f5b2 -- - debug

3 days

7
43
0 0

[PATCH 0/2] eventpoll: Fix epoll_wait() report false negative

by Nam Cao

Hi, While staring at epoll, I noticed ep_events_available() looks wrong. I wrote a small program to confirm, and yes it is definitely wrong. This series adds a reproducer to kselftest, and fix the bug. Nam Cao (2): selftests/eventpoll: Add test for multiple waiters eventpoll: Fix epoll_wait() report false negative fs/eventpoll.c | 16 +------ .../filesystems/epoll/epoll_wakeup_test.c | 45 +++++++++++++++++++ 2 files changed, 47 insertions(+), 14 deletions(-) -- 2.39.5

1 week

5
15
0 0

[PATCH v7 0/6] mm/memfd: introduce MFD_NOEXEC_SEAL and MFD_EXEC

by jeffxu＠chromium.org

From: Jeff Xu <jeffxu(a)google.com> Since Linux introduced the memfd feature, memfd have always had their execute bit set, and the memfd_create() syscall doesn't allow setting it differently. However, in a secure by default system, such as ChromeOS, (where all executables should come from the rootfs, which is protected by Verified boot), this executable nature of memfd opens a door for NoExec bypass and enables “confused deputy attack”. E.g, in VRP bug [1]: cros_vm process created a memfd to share the content with an external process, however the memfd is overwritten and used for executing arbitrary code and root escalation. [2] lists more VRP in this kind. On the other hand, executable memfd has its legit use, runc uses memfd’s seal and executable feature to copy the contents of the binary then execute them, for such system, we need a solution to differentiate runc's use of executable memfds and an attacker's [3]. To address those above, this set of patches add following: 1> Let memfd_create() set X bit at creation time. 2> Let memfd to be sealed for modifying X bit. 3> A new pid namespace sysctl: vm.memfd_noexec to control the behavior of X bit.For example, if a container has vm.memfd_noexec=2, then memfd_create() without MFD_NOEXEC_SEAL will be rejected. 4> A new security hook in memfd_create(). This make it possible to a new LSM, which rejects or allows executable memfd based on its security policy. Change history: v7: - patch 2/6: remove #ifdef and MAX_PATH (memfd_test.c). - patch 3/6: check capability (CAP_SYS_ADMIN) from userns instead of global ns (pid_sysctl.h). Add a tab (pid_namespace.h). - patch 5/6: remove #ifdef (memfd_test.c) - patch 6/6: remove unneeded security_move_mount(security.c). v6:https://lore.kernel.org/lkml/20221206150233.1963717-1-jeffxu@google.com/ - Address comment and move "#ifdef CONFIG_" from .c file to pid_sysctl.h v5:https://lore.kernel.org/lkml/20221206152358.1966099-1-jeffxu@google.com/ - Pass vm.memfd_noexec from current ns to child ns. - Fix build issue detected by kernel test robot. - Add missing security.c v3:https://lore.kernel.org/lkml/20221202013404.163143-1-jeffxu@google.com/ - Address API design comments in v2. - Let memfd_create() to set X bit at creation time. - A new pid namespace sysctl: vm.memfd_noexec to control behavior of X bit. - A new security hook in memfd_create(). v2:https://lore.kernel.org/lkml/20220805222126.142525-1-jeffxu@google.com/ - address comments in V1. - add sysctl (vm.mfd_noexec) to set the default file permissions of memfd_create to be non-executable. v1:https://lwn.net/Articles/890096/ [1] https://crbug.com/1305411 [2] https://bugs.chromium.org/p/chromium/issues/list?q=type%3Dbug-security%20me… [3] https://lwn.net/Articles/781013/ Daniel Verkamp (2): mm/memfd: add F_SEAL_EXEC selftests/memfd: add tests for F_SEAL_EXEC Jeff Xu (4): mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC mm/memfd: Add write seals when apply SEAL_EXEC to executable memfd selftests/memfd: add tests for MFD_NOEXEC_SEAL MFD_EXEC mm/memfd: security hook for memfd_create include/linux/lsm_hook_defs.h | 1 + include/linux/lsm_hooks.h | 4 + include/linux/pid_namespace.h | 19 ++ include/linux/security.h | 6 + include/uapi/linux/fcntl.h | 1 + include/uapi/linux/memfd.h | 4 + kernel/pid_namespace.c | 5 + kernel/pid_sysctl.h | 59 ++++ mm/memfd.c | 61 +++- mm/shmem.c | 6 + security/security.c | 5 + tools/testing/selftests/memfd/fuse_test.c | 1 + tools/testing/selftests/memfd/memfd_test.c | 341 ++++++++++++++++++++- 13 files changed, 510 insertions(+), 3 deletions(-) create mode 100644 kernel/pid_sysctl.h base-commit: eb7081409f94a9a8608593d0fb63a1aa3d6f95d8 -- 2.39.0.rc1.256.g54fd8350bd-goog

1 week, 2 days

9
25
0 0

[PATCH v4 0/7] Add support for FEAT_{LS64, LS64_V} and related tests

by Yicong Yang

From: Yicong Yang <yangyicong(a)hisilicon.com> Armv8.7 introduces single-copy atomic 64-byte loads and stores instructions and its variants named under FEAT_{LS64, LS64_V}. Add support for Armv8.7 FEAT_{LS64, LS64_V}: - Add identifying and enabling in the cpufeature list - Expose the support of these features to userspace through HWCAP3 and cpuinfo - Add related hwcap test - Handle the trap of unsupported memory (normal/uncacheable) access in a VM A real scenario for this feature is that the userspace driver can make use of this to implement direct WQE (workqueue entry) - a mechanism to fill WQE directly into the hardware. Picked Marc's 2 patches form [1] for handling the LS64 trap in a VM on emulated MMIO and the introduce of KVM_EXIT_ARM_LDST64B. [1] https://lore.kernel.org/linux-arm-kernel/20240815125959.2097734-1-maz@kerne… Tested with updated hwcap test: [root@localhost tmp]# dmesg | grep "All CPU(s) started" [ 14.789859] CPU: All CPU(s) started at EL2 [root@localhost tmp]# ./hwcap # LS64 present ok 217 cpuinfo_match_LS64 ok 218 sigill_LS64 ok 219 # SKIP sigbus_LS64_V # LS64_V present ok 220 cpuinfo_match_LS64_V ok 221 sigill_LS64_V ok 222 # SKIP sigbus_LS64_V # 115 skipped test(s) detected. Consider enabling relevant config options to improve coverage. # Totals: pass:107 fail:0 xfail:0 xpass:0 skip:115 error:0 root@localhost:/mnt# dmesg | grep "All CPU(s) started" [ 0.281152] CPU: All CPU(s) started at EL1 root@localhost:/mnt# ./hwcap # LS64 present ok 217 cpuinfo_match_LS64 ok 218 sigill_LS64 ok 219 # SKIP sigbus_LS64 # LS64_V present ok 220 cpuinfo_match_LS64_V ok 221 sigill_LS64_V ok 222 # SKIP sigbus_LS64_V # 115 skipped test(s) detected. Consider enabling relevant config options to improve coverage. # Totals: pass:107 fail:0 xfail:0 xpass:0 skip:115 error:0 Change since v3: - Inject DABT fault for LS64 fault on unsupported memory but with valid memslot Link: https://lore.kernel.org/linux-arm-kernel/20250626080906.64230-1-yangyicong@… Change since v2: - Handle the LS64 fault to userspace and allow userspace to inject LS64 fault - Reorder the patches to make KVM handling prior to feature support Link: https://lore.kernel.org/linux-arm-kernel/20250331094320.35226-1-yangyicong@… Change since v1: - Drop the support for LS64_ACCDATA - handle the DABT of unsupported memory type after checking the memory attributes Link: https://lore.kernel.org/linux-arm-kernel/20241202135504.14252-1-yangyicong@… Marc Zyngier (2): KVM: arm64: Add exit to userspace on {LD,ST}64B* outside of memslots KVM: arm64: Add documentation for KVM_EXIT_ARM_LDST64B Yicong Yang (5): KVM: arm64: Handle DABT caused by LS64* instructions on unsupported memory arm64: Provide basic EL2 setup for FEAT_{LS64, LS64_V} usage at EL0/1 arm64: Add support for FEAT_{LS64, LS64_V} KVM: arm64: Enable FEAT_{LS64, LS64_V} in the supported guest kselftest/arm64: Add HWCAP test for FEAT_{LS64, LS64_V} Documentation/arch/arm64/booting.rst | 12 +++ Documentation/arch/arm64/elf_hwcaps.rst | 6 ++ Documentation/virt/kvm/api.rst | 43 +++++++++-- arch/arm64/include/asm/el2_setup.h | 12 ++- arch/arm64/include/asm/esr.h | 8 ++ arch/arm64/include/asm/hwcap.h | 2 + arch/arm64/include/asm/kvm_emulate.h | 7 ++ arch/arm64/include/uapi/asm/hwcap.h | 2 + arch/arm64/kernel/cpufeature.c | 51 +++++++++++++ arch/arm64/kernel/cpuinfo.c | 2 + arch/arm64/kvm/inject_fault.c | 29 ++++++++ arch/arm64/kvm/mmio.c | 27 ++++++- arch/arm64/kvm/mmu.c | 14 +++- arch/arm64/tools/cpucaps | 2 + include/uapi/linux/kvm.h | 3 +- tools/testing/selftests/arm64/abi/hwcap.c | 90 +++++++++++++++++++++++ 16 files changed, 299 insertions(+), 11 deletions(-) -- 2.24.0

1 week, 4 days

4
18
0 0

[PATCH v2 00/16] selftests: vDSO: parse_vdso: Make compatible with nolibc

by Thomas Weißschuh

For testing the functionality of the vDSO, it is necessary to build userspace programs for multiple different architectures. It is additional work to acquire matching userspace cross-compilers with full C libraries and then building root images out of those. The kernel tree already contains nolibc, a small, header-only C library. By using it, it is possible to build userspace programs without any additional dependencies. For example the kernel.org crosstools or multi-target clang can be used to build test programs for a multitude of architectures. While nolibc is very limited, it is enough for many selftests. With some minor adjustments it is possible to make parse_vdso.c compatible with nolibc. As an example, vdso_standalone_test_x86 is now built from the same C code as the regular vdso_test_gettimeofday, while still being completely standalone. Also drop the dependency of parse_vdso.c on the elf.h header from libc and only use the one from the kernel's UAPI. While this series is useful on its own now, it will also integrate with the kunit UAPI framework currently under development: https://lore.kernel.org/lkml/20250217-kunit-kselftests-v1-0-42b4524c3b0a@li… Signed-off-by: Thomas Weißschuh <thomas.weissschuh(a)linutronix.de> --- Changes in v2: - Provide a limits.h header in nolibc - Pick up Reviewed-by tags from Kees - Link to v1: https://lore.kernel.org/r/20250203-parse_vdso-nolibc-v1-0-9cb6268d77be@linu… --- Thomas Weißschuh (16): MAINTAINERS: Add vDSO selftests elf, uapi: Add definition for STN_UNDEF elf, uapi: Add definition for DT_GNU_HASH elf, uapi: Add definitions for VER_FLG_BASE and VER_FLG_WEAK elf, uapi: Add type ElfXX_Versym elf, uapi: Add types ElfXX_Verdef and ElfXX_Veraux tools/include: Add uapi/linux/elf.h selftests: Add headers target tools/nolibc: add limits.h shim header selftests: vDSO: vdso_standalone_test_x86: Use vdso_init_form_sysinfo_ehdr selftests: vDSO: parse_vdso: Drop vdso_init_from_auxv() selftests: vDSO: parse_vdso: Use UAPI headers instead of libc headers selftests: vDSO: parse_vdso: Test __SIZEOF_LONG__ instead of ULONG_MAX selftests: vDSO: vdso_test_gettimeofday: Clean up includes selftests: vDSO: vdso_test_gettimeofday: Make compatible with nolibc selftests: vDSO: vdso_standalone_test_x86: Switch to nolibc MAINTAINERS | 1 + include/uapi/linux/elf.h | 38 ++ tools/include/nolibc/Makefile | 1 + tools/include/nolibc/limits.h | 7 + tools/include/uapi/linux/elf.h | 524 +++++++++++++++++++++ tools/testing/selftests/lib.mk | 5 +- tools/testing/selftests/vDSO/Makefile | 11 +- tools/testing/selftests/vDSO/parse_vdso.c | 19 +- tools/testing/selftests/vDSO/parse_vdso.h | 1 - .../selftests/vDSO/vdso_standalone_test_x86.c | 143 +----- .../selftests/vDSO/vdso_test_gettimeofday.c | 4 +- 11 files changed, 590 insertions(+), 164 deletions(-) --- base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b change-id: 20241017-parse_vdso-nolibc-e069baa7ff48 Best regards, -- Thomas Weißschuh <thomas.weissschuh(a)linutronix.de>

1 week, 5 days

7
42
0 0

[PATCH] selftests/filesystems: Fix build warning on anon_inode_test

by Ranganath V N

clang warning null passed where non-null argument is expected. anon_inode_test.c:45:19: warning: argument 3 null where non-null expected [-Wnonnull] 45 | ASSERT_LT(execveat(fd_context, "", NULL, NULL, AT_EMPTY_PATH), 0); | ^~~~~~~~ Signed-off-by: Ranganath V N <vnranganath.20(a)gmail.com> --- tools/testing/selftests/filesystems/anon_inode_test.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/filesystems/anon_inode_test.c b/tools/testing/selftests/filesystems/anon_inode_test.c index 73e0a4d4fb2f..f796dad679db 100644 --- a/tools/testing/selftests/filesystems/anon_inode_test.c +++ b/tools/testing/selftests/filesystems/anon_inode_test.c @@ -38,11 +38,13 @@ TEST(anon_inode_no_chmod) TEST(anon_inode_no_exec) { int fd_context; + static char *argv[] = { NULL }; + static char *envp[] = { NULL }; fd_context = sys_fsopen("tmpfs", 0); ASSERT_GE(fd_context, 0); - ASSERT_LT(execveat(fd_context, "", NULL, NULL, AT_EMPTY_PATH), 0); + ASSERT_LT(execveat(fd_context, "", argv, envp, AT_EMPTY_PATH), 0); ASSERT_EQ(errno, EACCES); EXPECT_EQ(close(fd_context), 0); -- 2.43.0

2 weeks, 5 days

1
1
0 0

[PATCH v21 0/9] PCI: EP: Add RC-to-EP doorbell with platform MSI controller

by Frank Li via B4 Relay

┌────────────┐ ┌───────────────────────────────────┐ ┌────────────────┐ │ │ │ │ │ │ │ │ │ PCI Endpoint │ │ PCI Host │ │ │ │ │ │ │ │ │◄──┤ 1.platform_msi_domain_alloc_irqs()│ │ │ │ │ │ │ │ │ │ MSI ├──►│ 2.write_msi_msg() ├──►├─BAR<n> │ │ Controller │ │ update doorbell register address│ │ │ │ │ │ for BAR │ │ │ │ │ │ │ │ 3. Write BAR<n>│ │ │◄──┼───────────────────────────────────┼───┤ │ │ │ │ │ │ │ │ ├──►│ 4.Irq Handle │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ └────────────┘ └───────────────────────────────────┘ └────────────────┘ This patches based on old https://lore.kernel.org/imx/20221124055036.1630573-1-Frank.Li@nxp.com/ Original patch only target to vntb driver. But actually it is common method. This patches add new API to pci-epf-core, so any EP driver can use it. Previous v2 discussion here. https://lore.kernel.org/imx/20230911220920.1817033-1-Frank.Li@nxp.com/ Changes in v21: - Align to bar size, try to fix Niklas reported problem. - Rebase to v6.16-rc5 - Link to v20: https://lore.kernel.org/r/20250709-ep-msi-v20-0-43d56f9bd54a@nxp.com Changes in v20: - remove set epf of_node's patch and only support one epf now. - move imx6's patch to first - detail change see each patches' change log - Link to v19: https://lore.kernel.org/r/20250609-ep-msi-v19-0-77362eaa48fa@nxp.com Changes in v19: - irq part already in v6.16-rc1, only missed pcie/dts part - rebase to v6.16-rc1 - update commit message for patch IMMUTABLE check. - Link to v18: https://lore.kernel.org/r/20250414-ep-msi-v18-0-f69b49917464@nxp.com Changes in v18: - pci-ep.yaml: sort property order, fix maxvalue to 0x7ffff for msi-map-mask and iommu-map-mask - Link to v17: https://lore.kernel.org/r/20250407-ep-msi-v17-0-633ab45a31d0@nxp.com Changes in v17: - move document part to pci-ep.yaml - Link to v16: https://lore.kernel.org/r/20250404-ep-msi-v16-0-d4919d68c0d0@nxp.com Changes in v16: - remove arm64: dts: imx95-19x19-evk: Add PCIe1 endpoint function overlay file because there are better patches, which under review. - Add document for pcie-ep msi-map usage - other change to see each patch's change log About IMMUTABLE (No change for this part, tglx provide feedback) > - This IMMUTABLE thing serves no purpose, because you don't randomly > plug this end-point block on any MSI controller. They come as part > of an SoC. "Yes and no. The problem is that the EP implementation is meant to be a generic library and while GIC-ITS guarantees immutability of the address/data pair after setup, there are architectures (x86, loongson, riscv) where the base MSI controller does not and immutability is only achieved when interrupt remapping is enabled. The latter can be disabled at boot-time and then the EP implementation becomes a lottery across affinity changes. That was my concern about this library implementation and that's why I asked for a mechanism to ensure that the underlying irqdomain provides a immutable address/data pair. So it does not matter for GIC-ITS, but in the larger picture it matters. Thanks, tglx " So it does not matter for GIC-ITS, but in the larger picture it matters. - Link to v15: https://lore.kernel.org/r/20250211-ep-msi-v15-0-bcacc1f2b1a9@nxp.com Changes in v15: - rebase to v6.14-rc1 - fix build issue find by kernel test robot - Link to v14: https://lore.kernel.org/r/20250207-ep-msi-v14-0-9671b136f2b8@nxp.com Changes in v14: Marc Zyngier raised concerns about adding DOMAIN_BUS_DEVICE_PCI_EP_MSI. As a result, the approach has been reverted to the v9 method. However, there are several improvements: MSI now supports msi-map in addition to msi-parent. - The struct device: id is used as the endpoint function (EPF) device identity to map to the stream ID (sideband information). - The EPC device tree source (DTS) utilizes msi-map to provide such information. - The EPF device's of_node is set to the EPC controller’s node. This approach is commonly used for multi-function device (MFD) platform child devices, allowing them to inherit properties from the MFD device’s DTS, such as reset-cells and gpio-cells. This method is well-suited for the current case, as the EPF is inherently created/binded to the EPC and should inherit the EPC’s DTS node properties. Additionally: Since the basic IMX95 LUT support has already been merged into the mainline, a DTS and driver increment patch is added to complete the solution. The patch is rebased onto the latest linux-next tree and aligned with the new pcitest framework. - Link to v13: https://lore.kernel.org/r/20241218-ep-msi-v13-0-646e2192dc24@nxp.com Changes in v13: - Change to use DOMAIN_BUS_PCI_DEVICE_EP_MSI - Change request id as func | vfunc << 3 - Remove IRQ_DOMAIN_MSI_IMMUTABLE Thomas Gleixner: I hope capture all your points in review comments. If missed, let me know. - Link to v12: https://lore.kernel.org/r/20241211-ep-msi-v12-0-33d4532fa520@nxp.com Changes in v12: - Change to use IRQ_DOMAIN_MSI_IMMUTABLE and add help function irq_domain_msi_is_immuatble(). - split PCI: endpoint: pci-ep-msi: Add MSI address/data pair mutable check to 3 patches - Link to v11: https://lore.kernel.org/r/20241209-ep-msi-v11-0-7434fa8397bd@nxp.com Changes in v11: - Change to use MSI_FLAG_MSG_IMMUTABLE - Link to v10: https://lore.kernel.org/r/20241204-ep-msi-v10-0-87c378dbcd6d@nxp.com Changes in v10: Thomas Gleixner: There are big change in pci-ep-msi.c. I am sure if go on the corrent path. The key improvement is remove only 1 function devices's limitation. I use new patch for imutable check, which relative additional feature compared to base enablement patch. - Remove patch Add msi_remove_device_irq_domain() in platform_device_msi_free_irqs_all() - Add new patch irqchip/gic-v3-its: Avoid overwriting msi_prepare callback if provided by msi_domain_info - Remove only support 1 endpoint function limiation. - Create one MSI domain for each endpoint function devices. - Use "msi-map" in pci ep controler node, instead of of msi-parent. first argument is (func_no << 8 | vfunc_no) - Link to v9: https://lore.kernel.org/r/20241203-ep-msi-v9-0-a60dbc3f15dd@nxp.com Changes in v9 - Add patch platform-msi: Add msi_remove_device_irq_domain() in platform_device_msi_free_irqs_all() - Remove patch PCI: endpoint: Add pci_epc_get_fn() API for customizable filtering - Remove API pci_epf_align_inbound_addr_lo_hi - Move doorbell_alloc in to doorbell_enable function. - Link to v8: https://lore.kernel.org/r/20241116-ep-msi-v8-0-6f1f68ffd1bb@nxp.com Changes in v8: - update helper function name to pci_epf_align_inbound_addr() - Link to v7: https://lore.kernel.org/r/20241114-ep-msi-v7-0-d4ac7aafbd2c@nxp.com Changes in v7: - Add helper function pci_epf_align_addr(); - Link to v6: https://lore.kernel.org/r/20241112-ep-msi-v6-0-45f9722e3c2a@nxp.com Changes in v6: - change doorbell_addr to doorbell_offset - use round_down() - add Niklas's test by tag - rebase to pci/endpoint - Link to v5: https://lore.kernel.org/r/20241108-ep-msi-v5-0-a14951c0d007@nxp.com Changes in v5: - Move request_irq to epf test function driver for more flexiable user case - Add fixed size bar handler - Some minor improvememtn to see each patches's changelog. - Link to v4: https://lore.kernel.org/r/20241031-ep-msi-v4-0-717da2d99b28@nxp.com Changes in v4: - Remove patch genirq/msi: Add cleanup guard define for msi_lock_descs()/msi_unlock_descs() - Use new method to avoid compatible problem. Add new command DOORBELL_ENABLE and DOORBELL_DISABLE. pcitest -B send DOORBELL_ENABLE first, EP test function driver try to remap one of BAR_N (except test register bar) to ITS MSI MMIO space. Old driver don't support new command, so failure return, not side effect. After test, DOORBELL_DISABLE command send out to recover original map, so pcitest bar test can pass as normal. - Other detail change see each patches's change log - Link to v3: https://lore.kernel.org/r/20241015-ep-msi-v3-0-cedc89a16c1a@nxp.com Change from v2 to v3 - Fixed manivannan's comments - Move common part to pci-ep-msi.c and pci-ep-msi.h - rebase to 6.12-rc1 - use RevID to distingiush old version mkdir /sys/kernel/config/pci_ep/functions/pci_epf_test/func1 echo 16 > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/msi_interrupts echo 0x080c > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/deviceid echo 0x1957 > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/vendorid echo 1 > /sys/kernel/config/pci_ep/functions/pci_epf_test/func1/revid ^^^^^^ to enable platform msi support. ln -s /sys/kernel/config/pci_ep/functions/pci_epf_test/func1 /sys/kernel/config/pci_ep/controllers/4c380000.pcie-ep - use new device ID, which identify support doorbell to avoid broken compatility. Enable doorbell support only for PCI_DEVICE_ID_IMX8_DB, while other devices keep the same behavior as before. EP side RC with old driver RC with new driver PCI_DEVICE_ID_IMX8_DB no probe doorbell enabled Other device ID doorbell disabled* doorbell disabled* * Behavior remains unchanged. Change from v1 to v2 - Add missed patch for endpont/pci-epf-test.c - Move alloc and free to epc driver from epf. - Provide general help function for EPC driver to alloc platform msi irq. - Fixed manivannan's comments. Signed-off-by: Frank Li <Frank.Li(a)nxp.com> --- Frank Li (9): PCI: imx6: Add helper function imx_pcie_add_lut_by_rid() PCI: imx6: Add LUT configuration for MSI/IOMMU in Endpoint mode PCI: endpoint: Add RC-to-EP doorbell support using platform MSI controller PCI: endpoint: pci-ep-msi: Add MSI address/data pair mutable check PCI: endpoint: Add pci_epf_align_inbound_addr() helper for address alignment PCI: endpoint: pci-epf-test: Add doorbell test support misc: pci_endpoint_test: Add doorbell test case selftests: pci_endpoint: Add doorbell test case arm64: dts: imx95: Add msi-map for pci-ep device Documentation/PCI/endpoint/pci-test-howto.rst | 14 +++ arch/arm64/boot/dts/freescale/imx95.dtsi | 1 + drivers/misc/pci_endpoint_test.c | 85 ++++++++++++- drivers/pci/controller/dwc/pci-imx6.c | 25 ++-- drivers/pci/endpoint/Kconfig | 8 ++ drivers/pci/endpoint/Makefile | 1 + drivers/pci/endpoint/functions/pci-epf-test.c | 136 +++++++++++++++++++++ drivers/pci/endpoint/pci-ep-msi.c | 98 +++++++++++++++ drivers/pci/endpoint/pci-epf-core.c | 36 ++++++ include/linux/pci-ep-msi.h | 28 +++++ include/linux/pci-epf.h | 18 +++ include/uapi/linux/pcitest.h | 1 + .../selftests/pci_endpoint/pci_endpoint_test.c | 28 +++++ 13 files changed, 470 insertions(+), 9 deletions(-) --- base-commit: d7b8f8e20813f0179d8ef519541a3527e7661d3a change-id: 20241010-ep-msi-8b4cab33b1be Best regards, -- Frank Li <Frank.Li(a)nxp.com>

2 weeks, 5 days

5
16
0 0

[PATCH] selftests/filesystems: Use return value of the function 'chdir()'

by Alessandro Zanni

Fix to use the return value of the function 'chdir("/")' and check if the return is either 0 (ok) or 1 (not ok, so the test stops). The patch fies the solves the following errors: mount-notify_test.c:468:17: warning: ignoring return value of ‘chdir’ declared with attribute ‘warn_unused_result’ [-Wunused-result] 468 | chdir("/"); mount-notify_test_ns.c:489:17: warning: ignoring return value of ‘chdir’ declared with attribute ‘warn_unused_result’ [-Wunused- result] 489 | chdir("/"); To reproduce the issue, use the command: make kselftest TARGET=filesystems/statmount Signed-off-by: Alessandro Zanni <alessandro.zanni87(a)gmail.com> --- .../selftests/filesystems/mount-notify/mount-notify_test.c | 2 +- .../selftests/filesystems/mount-notify/mount-notify_test_ns.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c index 5a3b0ace1a88..a7f899599d52 100644 --- a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c +++ b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c @@ -458,7 +458,7 @@ TEST_F(fanotify, rmdir) ASSERT_GE(ret, 0); if (ret == 0) { - chdir("/"); + ASSERT_EQ(0, chdir("/")); unshare(CLONE_NEWNS); mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL); umount2("/a", MNT_DETACH); diff --git a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c index d91946e69591..dc9eb3087a1a 100644 --- a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c +++ b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c @@ -486,7 +486,7 @@ TEST_F(fanotify, rmdir) ASSERT_GE(ret, 0); if (ret == 0) { - chdir("/"); + ASSERT_EQ(0, chdir("/")); unshare(CLONE_NEWNS); mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL); umount2("/a", MNT_DETACH); -- 2.43.0

3 weeks

2
1
0 0

[PATCH v3] selftests/tty: add TIOCSTI test suite

by Abhinav Saxena

TIOCSTI is a TTY ioctl command that allows inserting characters into the terminal input queue, making it appear as if the user typed those characters. This functionality has behavior that varies based on system configuration and process credentials. The dev.tty.legacy_tiocsti sysctl introduced in commit 83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled") controls TIOCSTI usage. When disabled, TIOCSTI requires CAP_SYS_ADMIN capability. The current implementation checks the current process's credentials via capable(CAP_SYS_ADMIN), but does not validate against the file opener's credentials stored in file->f_cred. This creates different behavior when file descriptors are passed between processes via SCM_RIGHTS. Add a test suite with 16 test variants using fixture variants to verify TIOCSTI behavior when dev.tty.legacy_tiocsti is enabled/disabled: - Basic TIOCSTI tests (8 variants): Direct testing with different capability and controlling terminal combinations - FD passing tests (8 variants): Test behavior when file descriptors are passed between processes with different capabilities The FD passing tests document this behavior - some tests show different results than expected based on file opener credentials, demonstrating that TIOCSTI uses current process credentials rather than file opener credentials. The tests validate proper enforcement of the legacy_tiocsti sysctl. Test implementation uses openpty(3) with TIOCSCTTY for isolated PTY environments. See tty_ioctl(4) for details on TIOCSTI behavior and security requirements. Signed-off-by: Abhinav Saxena <xandfury(a)gmail.com> --- To run all tests: $ sudo ./tools/testing/selftests/tty/tty_tiocsti_test Test Results: - PASSED: 13/16 tests - Different behavior: 3/16 tests (documenting credential checking behavior) All tests validated using: - scripts/checkpatch.pl --strict (clean output) - Functional testing on kernel v6.16-rc2 Changes in v3: - Replaced all printf() calls with TH_LOG() for proper test logging (Kees Cook) - Added struct __test_metadata parameter to helper functions - Moved common legacy_tiocsti availability check to FIXTURE_SETUP() - Implemented sysctl modification/restoration in FIXTURE_SETUP/TEARDOWN - Used openpty() with TIOCSCTTY for reliable PTY testing environment - Fixed child/parent synchronization in FD passing tests - Replaced manual _exit(1) handling with proper ASSERT statements - Switched // comments to /* */ format throughout - Expanded to 16 test variants using fixture variants - Enhanced error handling and test reliability - Link to v2: https://lore.kernel.org/r/20250713-toicsti-bug-v2-1-b183787eea29@gmail.com - Link to v1: https://lore.kernel.org/r/20250622-toicsti-bug-v1-0-f374373b04b2@gmail.com References: - tty_ioctl(4) - documents TIOCSTI ioctl and capability requirements - openpty(3) - pseudo-terminal creation and management - commit 83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled") - Documentation/security/credentials.rst - https://github.com/KSPP/linux/issues/156 - https://lore.kernel.org/linux-hardening/Y0m9l52AKmw6Yxi1@hostpad/ - drivers/tty/Kconfig - Documentation/driver-api/tty/ --- tools/testing/selftests/tty/Makefile | 6 +- tools/testing/selftests/tty/config | 1 + tools/testing/selftests/tty/tty_tiocsti_test.c | 650 +++++++++++++++++++++++++ 3 files changed, 656 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/tty/Makefile b/tools/testing/selftests/tty/Makefile index 50d7027b2ae3..7f6fbe5a0cd5 100644 --- a/tools/testing/selftests/tty/Makefile +++ b/tools/testing/selftests/tty/Makefile @@ -1,5 +1,9 @@ # SPDX-License-Identifier: GPL-2.0 CFLAGS = -O2 -Wall -TEST_GEN_PROGS := tty_tstamp_update +TEST_GEN_PROGS := tty_tstamp_update tty_tiocsti_test +LDLIBS += -lcap include ../lib.mk + +# Add libcap for TIOCSTI test +$(OUTPUT)/tty_tiocsti_test: LDLIBS += -lcap diff --git a/tools/testing/selftests/tty/config b/tools/testing/selftests/tty/config new file mode 100644 index 000000000000..c6373aba6636 --- /dev/null +++ b/tools/testing/selftests/tty/config @@ -0,0 +1 @@ +CONFIG_LEGACY_TIOCSTI=y diff --git a/tools/testing/selftests/tty/tty_tiocsti_test.c b/tools/testing/selftests/tty/tty_tiocsti_test.c new file mode 100644 index 000000000000..1eafef6e36fa --- /dev/null +++ b/tools/testing/selftests/tty/tty_tiocsti_test.c @@ -0,0 +1,650 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * TTY Tests - TIOCSTI + * + * Copyright © 2025 Abhinav Saxena <xandfury(a)gmail.com> + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <fcntl.h> +#include <sys/ioctl.h> +#include <errno.h> +#include <stdbool.h> +#include <string.h> +#include <sys/socket.h> +#include <sys/wait.h> +#include <pwd.h> +#include <termios.h> +#include <grp.h> +#include <sys/capability.h> +#include <sys/prctl.h> +#include <pty.h> +#include <utmp.h> + +#include "../kselftest_harness.h" + +enum test_type { + TEST_PTY_TIOCSTI_BASIC, + TEST_PTY_TIOCSTI_FD_PASSING, + /* other tests cases such as serial may be added. */ +}; + +/* + * Test Strategy: + * - Basic tests: Use PTY with/without TIOCSCTTY (controlling terminal for + * current process) + * - FD passing tests: Child creates PTY, parent receives FD (demonstrates + * security issue) + * + * SECURITY VULNERABILITY DEMONSTRATION: + * FD passing tests show that TIOCSTI uses CURRENT process credentials, not + * opener credentials. This means privileged processes can be given FDs from + * unprivileged processes and successfully perform TIOCSTI operations that the + * unprivileged process couldn't do directly. + * + * Attack scenario: + * 1. Unprivileged process opens TTY (direct TIOCSTI fails due to lack of + * privileges) + * 2. Unprivileged process passes FD to privileged process via SCM_RIGHTS + * 3. Privileged process can use TIOCSTI on the FD (succeeds due to its + * privileges) + * 4. Result: Effective privilege escalation via file descriptor passing + * + * This matches the kernel logic in tiocsti(): + * 1. if (!tty_legacy_tiocsti && !capable(CAP_SYS_ADMIN)) return -EIO; + * 2. if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN)) + * return -EPERM; + * Note: Both checks use capable() on CURRENT process, not FD opener! + * + * If the file credentials were also checked along with the capable() checks + * then the results for FD pass tests would be consistent with the basic tests. + */ + +FIXTURE(tiocsti) +{ + int pty_master_fd; /* PTY - for basic tests */ + int pty_slave_fd; + bool has_pty; + bool initial_cap_sys_admin; + int original_legacy_tiocsti_setting; + bool can_modify_sysctl; +}; + +FIXTURE_VARIANT(tiocsti) +{ + const enum test_type test_type; + const bool controlling_tty; /* true=current->signal->tty == tty */ + const int legacy_tiocsti; /* 0=restricted, 1=permissive */ + const bool requires_cap; /* true=with CAP_SYS_ADMIN, false=without */ + const int expected_success; /* 0=success, -EIO/-EPERM=specific error */ +}; + +/* + * Tests Controlling Terminal Variants (current->signal->tty == tty) + * + * TIOCSTI Test Matrix: + * + * | legacy_tiocsti | CAP_SYS_ADMIN | Expected Result | Error | + * |----------------|---------------|-----------------|-------| + * | 1 (permissive) | true | SUCCESS | - | + * | 1 (permissive) | false | SUCCESS | - | + * | 0 (restricted) | true | SUCCESS | - | + * | 0 (restricted) | false | FAILURE | -EIO | + */ + +/* clang-format off */ +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_pty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, /* FAILURE: legacy restriction */ +}; /* clang-format on */ + +/* + * Note for FD Passing Test Variants + * Since we're testing the scenario where an unprivileged process pass an FD + * to a privileged one, .requires_cap here means the caps of the child process. + * Not the parent; parent would always be privileged. + */ + +/* clang-format off */ +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_pty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = true, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, +}; /* clang-format on */ + +/* + * Non-Controlling Terminal Variants (current->signal->tty != tty) + * + * TIOCSTI Test Matrix: + * + * | legacy_tiocsti | CAP_SYS_ADMIN | Expected Result | Error | + * |----------------|---------------|-----------------|-------| + * | 1 (permissive) | true | SUCCESS | - | + * | 1 (permissive) | false | FAILURE | -EPERM| + * | 0 (restricted) | true | SUCCESS | - | + * | 0 (restricted) | false | FAILURE | -EIO | + */ + +/* clang-format off */ +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = -EPERM, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, basic_nopty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_BASIC, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_permissive_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_permissive_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 1, + .requires_cap = false, + .expected_success = -EPERM, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_restricted_withcap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = true, + .expected_success = 0, +}; + +FIXTURE_VARIANT_ADD(tiocsti, fdpass_nopty_restricted_nocap) { + .test_type = TEST_PTY_TIOCSTI_FD_PASSING, + .controlling_tty = false, + .legacy_tiocsti = 0, + .requires_cap = false, + .expected_success = -EIO, +}; /* clang-format on */ + +/* Helper function to send FD via SCM_RIGHTS */ +static int send_fd_via_socket(int socket_fd, int fd_to_send) +{ + struct msghdr msg = { 0 }; + struct cmsghdr *cmsg; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + char dummy_data = 'F'; + struct iovec iov = { .iov_base = &dummy_data, .iov_len = 1 }; + + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + + memcpy(CMSG_DATA(cmsg), &fd_to_send, sizeof(int)); + + return sendmsg(socket_fd, &msg, 0) < 0 ? -1 : 0; +} + +/* Helper function to receive FD via SCM_RIGHTS */ +static int recv_fd_via_socket(int socket_fd) +{ + struct msghdr msg = { 0 }; + struct cmsghdr *cmsg; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + char dummy_data; + struct iovec iov = { .iov_base = &dummy_data, .iov_len = 1 }; + int received_fd = -1; + + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + if (recvmsg(socket_fd, &msg, 0) < 0) + return -1; + + for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { + if (cmsg->cmsg_level == SOL_SOCKET && + cmsg->cmsg_type == SCM_RIGHTS) { + memcpy(&received_fd, CMSG_DATA(cmsg), sizeof(int)); + break; + } + } + + return received_fd; +} + +static inline bool has_cap_sys_admin(void) +{ + cap_t caps = cap_get_proc(); + + if (!caps) + return false; + + cap_flag_value_t cap_val; + bool has_cap = (cap_get_flag(caps, CAP_SYS_ADMIN, CAP_EFFECTIVE, + &cap_val) == 0) && + (cap_val == CAP_SET); + + cap_free(caps); + return has_cap; +} + +/* + * Drop to nobody user (uid/gid 65534) to lose all capabilities + */ +static inline bool drop_to_nobody(struct __test_metadata *_metadata) +{ + ASSERT_EQ(setgroups(0, NULL), 0); + ASSERT_EQ(setgid(65534), 0); + ASSERT_EQ(setuid(65534), 0); + + ASSERT_FALSE(has_cap_sys_admin()); + return true; +} + +static inline int get_legacy_tiocsti_setting(struct __test_metadata *_metadata) +{ + FILE *fp; + int value = -1; + + fp = fopen("/proc/sys/dev/tty/legacy_tiocsti", "r"); + if (!fp) { + /* legacy_tiocsti sysctl not available (kernel < 6.2) */ + return -1; + } + + if (fscanf(fp, "%d", &value) == 1) { + if (value < 0 || value > 1) + value = -1; /* Invalid value */ + } else { + value = -1; /* Failed to parse */ + } + + fclose(fp); + return value; +} + +static inline bool set_legacy_tiocsti_setting(struct __test_metadata *_metadata, + int value) +{ + FILE *fp; + bool success = false; + + /* Sanity-check the value */ + ASSERT_GE(value, 0); + ASSERT_LE(value, 1); + + /* + * Try to open for writing; if we lack permission, return false so + * the test harness will skip variants that need to change it + */ + fp = fopen("/proc/sys/dev/tty/legacy_tiocsti", "w"); + if (!fp) + return false; + + /* Write the new setting */ + if (fprintf(fp, "%d\n", value) > 0) + success = true; + else + TH_LOG("Failed to write legacy_tiocsti: %s", strerror(errno)); + + fclose(fp); + return success; +} + +/* + * TIOCSTI injection test function + * @tty_fd: TTY slave file descriptor to test TIOCSTI on + * Returns: 0 on success, -errno on failure + */ +static inline int test_tiocsti_injection(struct __test_metadata *_metadata, + int tty_fd) +{ + int ret; + char inject_char = 'V'; + + errno = 0; + ret = ioctl(tty_fd, TIOCSTI, &inject_char); + return ret == 0 ? 0 : -errno; +} + +FIXTURE_SETUP(tiocsti) +{ + /* Create PTY pair for basic tests */ + self->has_pty = (openpty(&self->pty_master_fd, &self->pty_slave_fd, + NULL, NULL, NULL) == 0); + if (!self->has_pty) { + self->pty_master_fd = -1; + self->pty_slave_fd = -1; + } + + self->initial_cap_sys_admin = has_cap_sys_admin(); + self->original_legacy_tiocsti_setting = + get_legacy_tiocsti_setting(_metadata); + + if (self->original_legacy_tiocsti_setting < 0) + SKIP(return, "legacy_tiocsti sysctl not available (kernel < 6.2)"); + + /* Test if we can modify the sysctl (requires appropriate privileges) */ + self->can_modify_sysctl = set_legacy_tiocsti_setting(_metadata, + self->original_legacy_tiocsti_setting); + if (!self->can_modify_sysctl) + TH_LOG("Warning: Cannot modify legacy_tiocsti sysctl - will skip mismatched variants"); +} + +FIXTURE_TEARDOWN(tiocsti) +{ + /* + * Backup restoration - + * each test should restore its own sysctl changes + */ + if (self->can_modify_sysctl && + self->original_legacy_tiocsti_setting >= 0) { + int current_value = get_legacy_tiocsti_setting(_metadata); + + if (current_value != self->original_legacy_tiocsti_setting) { + TH_LOG("Backup: Restoring legacy_tiocsti from %d to %d", + current_value, + self->original_legacy_tiocsti_setting); + set_legacy_tiocsti_setting(_metadata, + self->original_legacy_tiocsti_setting); + } + } + + if (self->has_pty) { + if (self->pty_master_fd >= 0) + close(self->pty_master_fd); + if (self->pty_slave_fd >= 0) + close(self->pty_slave_fd); + } +} + +TEST_F(tiocsti, test) +{ + int saved_legacy_tiocsti = get_legacy_tiocsti_setting(_metadata); + bool need_restore = false; + int status; + pid_t child_pid; + + /* Set legacy_tiocsti sysctl to match variant requirement */ + if (self->can_modify_sysctl) { + if (saved_legacy_tiocsti != variant->legacy_tiocsti) { + if (!set_legacy_tiocsti_setting(_metadata, + variant->legacy_tiocsti)) { + SKIP(return, + "Failed to set legacy_tiocsti sysctl"); + } + need_restore = true; + } + } else { + /* + * Can't modify sysctl + * - check if current value matches variant + */ + if (self->original_legacy_tiocsti_setting != + variant->legacy_tiocsti) { + SKIP(return, + "legacy_tiocsti setting mismatch and cannot modify sysctl"); + } + } + + /* Common skip conditions */ + if (variant->test_type == TEST_PTY_TIOCSTI_BASIC && !self->has_pty) { + SKIP(goto restore_sysctl, + "PTY not available for controlling terminal test"); + } + + if (variant->test_type == TEST_PTY_TIOCSTI_FD_PASSING && + !self->initial_cap_sys_admin) { + SKIP(goto restore_sysctl, + "FD Pass tests require CAP_SYS_ADMIN"); + } + + if (variant->requires_cap && !self->initial_cap_sys_admin) { + SKIP(goto restore_sysctl, + "Test requires initial CAP_SYS_ADMIN"); + } + + if (variant->test_type == TEST_PTY_TIOCSTI_BASIC) { + /* ===== BASIC TIOCSTI TEST ===== */ + child_pid = fork(); + ASSERT_GE(child_pid, 0); + + if (child_pid == 0) { + /* Child process - perform the actual test */ + + /* Handle capability requirements */ + if (self->initial_cap_sys_admin && + !variant->requires_cap) + ASSERT_TRUE(drop_to_nobody(_metadata)); + + if (variant->controlling_tty) { + /* + * Create new session and set PTY as + * controlling terminal + */ + pid_t sid = setsid(); + + ASSERT_GE(sid, 0); + ASSERT_EQ(ioctl(self->pty_slave_fd, TIOCSCTTY, + 0), + 0); + } + + /* + * Validate test environment setup and verify final + * capability state matches expectation + * after potential drop. + * + */ + ASSERT_TRUE(self->has_pty); + ASSERT_EQ(has_cap_sys_admin(), variant->requires_cap); + + /* Test TIOCSTI and validate result */ + int result = test_tiocsti_injection(_metadata, + self->pty_slave_fd); + + /* Check against expected result from variant */ + EXPECT_EQ(result, variant->expected_success); + _exit(0); + } + + } else { + /* ===== FD PASSING SECURITY TEST ===== */ + int sockpair[2]; + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sockpair), 0); + + child_pid = fork(); + ASSERT_GE(child_pid, 0); + + if (child_pid == 0) { + /* Child process - create PTY and send FD */ + close(sockpair[0]); + signal(SIGHUP, SIG_IGN); + + /* Handle privilege dropping */ + if (!variant->requires_cap && has_cap_sys_admin()) + ASSERT_TRUE(drop_to_nobody(_metadata)); + + /* Create child's PTY */ + int child_master_fd, child_slave_fd; + + ASSERT_EQ(openpty(&child_master_fd, &child_slave_fd, + NULL, NULL, NULL), + 0); + + if (variant->controlling_tty) { + pid_t sid = setsid(); + + ASSERT_GE(sid, 0); + ASSERT_EQ(ioctl(child_slave_fd, TIOCSCTTY, 0), + 0); + } + + /* Test child's direct TIOCSTI for reference */ + int direct_result = test_tiocsti_injection(_metadata, + child_slave_fd); + EXPECT_EQ(direct_result, variant->expected_success); + + /* Send FD to parent */ + ASSERT_EQ(send_fd_via_socket(sockpair[1], + child_slave_fd), + 0); + + /* Wait for parent completion signal */ + char sync_byte; + ssize_t bytes_read = read(sockpair[1], &sync_byte, 1); + + ASSERT_EQ(bytes_read, 1); + + close(child_master_fd); + close(child_slave_fd); + close(sockpair[1]); + _exit(0); + } + + /* Parent process - receive FD and test TIOCSTI */ + close(sockpair[1]); + + int received_fd = recv_fd_via_socket(sockpair[0]); + + ASSERT_GE(received_fd, 0); + + bool parent_has_cap = self->initial_cap_sys_admin; + + TH_LOG("=== TIOCSTI FD Passing Test Context ==="); + TH_LOG("legacy_tiocsti: %d, Parent CAP_SYS_ADMIN: %s, Child: %s", + variant->legacy_tiocsti, parent_has_cap ? "yes" : "no", + variant->requires_cap ? "kept" : "dropped"); + + /* SECURITY TEST: Try TIOCSTI with FD opened by child */ + int result = test_tiocsti_injection(_metadata, received_fd); + + /* Log security concern if demonstrated */ + if (result == 0 && !variant->requires_cap) { + TH_LOG("*** SECURITY CONCERN DEMONSTRATED ***"); + TH_LOG("Privileged parent can use TIOCSTI on FD from unprivileged child"); + TH_LOG("This shows current process credentials are used, not opener credentials"); + } + + EXPECT_EQ(result, variant->expected_success) + { + TH_LOG("FD passing: expected error %d, got %d", + variant->expected_success, result); + } + + /* Signal child completion */ + char sync_byte = 'D'; + ssize_t bytes_written = write(sockpair[0], &sync_byte, 1); + + ASSERT_EQ(bytes_written, 1); + + close(received_fd); + close(sockpair[0]); + } + + /* Common child process cleanup for both test types */ + ASSERT_EQ(waitpid(child_pid, &status, 0), child_pid); + + if (WIFSIGNALED(status)) { + TH_LOG("Child terminated by signal %d", WTERMSIG(status)); + ASSERT_FALSE(WIFSIGNALED(status)) + { + TH_LOG("Child process failed assertion"); + } + } else { + EXPECT_EQ(WEXITSTATUS(status), 0); + } + +restore_sysctl: + if (need_restore) + set_legacy_tiocsti_setting(_metadata, saved_legacy_tiocsti); +} + +TEST_HARNESS_MAIN --- base-commit: 283564a43383d6f26a55546fe9ae345b5fa95e66 change-id: 20250618-toicsti-bug-7822b8e94a32 Best regards, -- Abhinav Saxena <xandfury(a)gmail.com>

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