September 2025 - Linux-kselftest-mirror

[PATCH v3 00/12] Start porting UML to nolibc

by Benjamin Berg

From: Benjamin Berg <benjamin.berg(a)intel.com> This patchset is an attempt to start a nolibc port of UML. The goal is to port UML to use nolibc in smaller chunks to make the switch more manageable. Using nolibc has the advantage that it is a smaller runtime and it allows us to be in full control about all memory mappings that are done. Another libc on the other hand might map memory unaware of UML, causing collisions with the UML memory layout. Such mappings could even happen before UML has fully initialized (e.g. rseq being mapped into the physical or vmalloc memory areas). There are three parts to this patchset: * Two patches to use tools/include headers instead of kernel headers for userspace files. * A few nolibc fixes and a new NOLIBC_NO_RUNTIME compile flag for it * Finally nolibc build support for UML and switching two files while adding the appropriate support in nolibc itself. v1 of this patchset was https://lore.kernel.org/all/20250915071115.1429196-1-benjamin@sipsolutions.… v2: https://lore.kernel.org/all/20250919153420.727385-1-benjamin@sipsolutions.n… Changes in v3: - sys_ptrace is now not a varadic function - improve printf %m implementation - keep perror as function available with NOLIBC_IGNORE_ERRNO - change syscall guard and fix i386 build Changes in v2: - add sys/uio.h and sys/ptrace.h to nolibc - Use NOLIBC_NO_RUNTIME to disable nolibc startup code - Fix out-of-tree build - various small improvements and cleanups Benjamin Benjamin Berg (12): tools compiler.h: fix __used definition um: use tools/include for user files tools/nolibc/stdio: let perror work when NOLIBC_IGNORE_ERRNO is set tools/nolibc/dirent: avoid errno in readdir_r tools/nolibc: implement %m if errno is not defined tools/nolibc: use __fallthrough__ rather than fallthrough tools/nolibc: add option to disable runtime um: add infrastructure to build files using nolibc um: use nolibc for the --showconfig implementation tools/nolibc: add uio.h with readv and writev tools/nolibc: add ptrace support um: switch ptrace FP register access to nolibc arch/um/Makefile | 38 ++++++++++++--- arch/um/include/shared/init.h | 2 +- arch/um/include/shared/os.h | 2 + arch/um/include/shared/user.h | 6 --- arch/um/kernel/Makefile | 2 +- arch/um/kernel/skas/stub.c | 1 + arch/um/kernel/skas/stub_exe.c | 4 +- arch/um/os-Linux/skas/process.c | 6 +-- arch/um/os-Linux/start_up.c | 4 +- arch/um/scripts/Makefile.rules | 10 +++- arch/x86/um/Makefile | 6 ++- arch/x86/um/os-Linux/Makefile | 5 +- arch/x86/um/os-Linux/registers.c | 20 ++------ arch/x86/um/user-offsets.c | 1 - tools/include/linux/compiler.h | 2 +- tools/include/nolibc/Makefile | 2 + tools/include/nolibc/arch-arm.h | 2 + tools/include/nolibc/arch-arm64.h | 2 + tools/include/nolibc/arch-loongarch.h | 2 + tools/include/nolibc/arch-m68k.h | 2 + tools/include/nolibc/arch-mips.h | 2 + tools/include/nolibc/arch-powerpc.h | 2 + tools/include/nolibc/arch-riscv.h | 2 + tools/include/nolibc/arch-s390.h | 2 + tools/include/nolibc/arch-sh.h | 2 + tools/include/nolibc/arch-sparc.h | 2 + tools/include/nolibc/arch-x86.h | 4 ++ tools/include/nolibc/compiler.h | 4 +- tools/include/nolibc/crt.h | 3 ++ tools/include/nolibc/dirent.h | 6 +-- tools/include/nolibc/nolibc.h | 2 + tools/include/nolibc/stackprotector.h | 2 + tools/include/nolibc/stdio.h | 10 +++- tools/include/nolibc/stdlib.h | 2 + tools/include/nolibc/sys.h | 3 +- tools/include/nolibc/sys/auxv.h | 3 ++ tools/include/nolibc/sys/ptrace.h | 44 ++++++++++++++++++ tools/include/nolibc/sys/uio.h | 49 ++++++++++++++++++++ tools/testing/selftests/nolibc/nolibc-test.c | 11 +++++ 39 files changed, 221 insertions(+), 53 deletions(-) create mode 100644 tools/include/nolibc/sys/ptrace.h create mode 100644 tools/include/nolibc/sys/uio.h -- 2.51.0

20 hours, 39 minutes

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[PATCH v11 00/21] TDX KVM selftests

by Sagi Shahar

This is v11 of the TDX selftests. This series is based on v6.17-rc7 Changes from v10 [1]: - Rebased on top of v6.17-rc4. - Addressed minor comments from v10. - Removed code for setting up X86_CR4_OSXMMEXCPT which is not needed for now. - Added call to vm_tdx_load_common_boot_parameters() in "KVM: selftests: Call TDX init when creating a new TDX vm" which was accidentally dropped between v9 and v10 due to code refactoring [1] https://lore.kernel.org/lkml/20250904065453.639610-1-sagis@google.com/#r Ackerley Tng (2): KVM: selftests: Add helpers to init TDX memory and finalize VM KVM: selftests: Add ucall support for TDX Erdem Aktas (2): KVM: selftests: Add TDX boot code KVM: selftests: Add support for TDX TDCALL from guest Isaku Yamahata (2): KVM: selftests: Update kvm_init_vm_address_properties() for TDX KVM: selftests: TDX: Use KVM_TDX_CAPABILITIES to validate TDs' attribute configuration Sagi Shahar (15): KVM: selftests: Allocate pgd in virt_map() as necessary KVM: selftests: Expose functions to get default sregs values KVM: selftests: Expose function to allocate guest vCPU stack KVM: selftests: Expose segment definitons to assembly files KVM: selftests: Add kbuild definitons KVM: selftests: Define structs to pass parameters to TDX boot code KVM: selftests: Set up TDX boot code region KVM: selftests: Set up TDX boot parameters region KVM: selftests: Add helper to initialize TDX VM KVM: selftests: Call TDX init when creating a new TDX vm KVM: selftests: Setup memory regions for TDX on vm creation KVM: selftests: Call KVM_TDX_INIT_VCPU when creating a new TDX vcpu KVM: selftests: Set entry point for TDX guest code KVM: selftests: Add wrapper for TDX MMIO from guest KVM: selftests: Add TDX lifecycle test tools/include/linux/kbuild.h | 18 + tools/testing/selftests/kvm/Makefile.kvm | 32 ++ .../selftests/kvm/include/ucall_common.h | 1 + .../selftests/kvm/include/x86/processor.h | 35 ++ .../selftests/kvm/include/x86/processor_asm.h | 12 + .../selftests/kvm/include/x86/tdx/td_boot.h | 74 ++++ .../kvm/include/x86/tdx/td_boot_asm.h | 16 + .../selftests/kvm/include/x86/tdx/tdcall.h | 34 ++ .../selftests/kvm/include/x86/tdx/tdx.h | 14 + .../selftests/kvm/include/x86/tdx/tdx_util.h | 86 +++++ .../testing/selftests/kvm/include/x86/ucall.h | 6 - tools/testing/selftests/kvm/lib/kvm_util.c | 10 +- .../testing/selftests/kvm/lib/x86/processor.c | 93 +++-- .../selftests/kvm/lib/x86/tdx/td_boot.S | 60 +++ .../kvm/lib/x86/tdx/td_boot_offsets.c | 21 ++ .../selftests/kvm/lib/x86/tdx/tdcall.S | 93 +++++ .../kvm/lib/x86/tdx/tdcall_offsets.c | 16 + tools/testing/selftests/kvm/lib/x86/tdx/tdx.c | 23 ++ .../selftests/kvm/lib/x86/tdx/tdx_util.c | 348 ++++++++++++++++++ tools/testing/selftests/kvm/lib/x86/ucall.c | 46 ++- tools/testing/selftests/kvm/x86/tdx_vm_test.c | 31 ++ 21 files changed, 1029 insertions(+), 40 deletions(-) create mode 100644 tools/include/linux/kbuild.h create mode 100644 tools/testing/selftests/kvm/include/x86/processor_asm.h create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/td_boot.h create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/td_boot_asm.h create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/tdcall.h create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/tdx.h create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/td_boot_offsets.c create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/tdcall.S create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/tdcall_offsets.c create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/tdx.c create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c create mode 100644 tools/testing/selftests/kvm/x86/tdx_vm_test.c -- 2.51.0.536.g15c5d4f767-goog

1 day, 17 hours

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[PATCH v12] exec: Fix dead-lock in de_thread with ptrace_attach

by Bernd Edlinger

This introduces signal->exec_bprm, which is used to fix the case when at least one of the sibling threads is traced, and therefore the trace process may dead-lock in ptrace_attach, but de_thread will need to wait for the tracer to continue execution. The solution is to detect this situation and allow ptrace_attach to continue by temporarily releasing the cred_guard_mutex, while de_thread() is still waiting for traced zombies to be eventually released by the tracer. In the case of the thread group leader we only have to wait for the thread to become a zombie, which may also need co-operation from the tracer due to PTRACE_O_TRACEEXIT. When a tracer wants to ptrace_attach a task that already is in execve, we simply retry the ptrace_may_access check while temporarily installing the new credentials and dumpability which are about to be used after execve completes. If the ptrace_attach happens on a thread that is a sibling-thread of the thread doing execve, it is sufficient to check against the old credentials, as this thread will be waited for, before the new credentials are installed. Other threads die quickly since the cred_guard_mutex is released, but a deadly signal is already pending. In case the mutex_lock_killable misses the signal, the non-zero current->signal->exec_bprm makes sure they release the mutex immediately and return with -ERESTARTNOINTR. This means there is no API change, unlike the previous version of this patch which was discussed here: https://lore.kernel.org/lkml/b6537ae6-31b1-5c50-f32b-8b8332ace882@hotmail.d… See tools/testing/selftests/ptrace/vmaccess.c for a test case that gets fixed by this change. Note that since the test case was originally designed to test the ptrace_attach returning an error in this situation, the test expectation needed to be adjusted, to allow the API to succeed at the first attempt. Signed-off-by: Bernd Edlinger <bernd.edlinger(a)hotmail.de> --- fs/exec.c | 69 ++++++++++++++++------- fs/proc/base.c | 6 ++ include/linux/cred.h | 1 + include/linux/sched/signal.h | 18 ++++++ kernel/cred.c | 28 +++++++-- kernel/ptrace.c | 32 +++++++++++ kernel/seccomp.c | 12 +++- tools/testing/selftests/ptrace/vmaccess.c | 23 +++++--- 8 files changed, 155 insertions(+), 34 deletions(-) v10: Changes to previous version, make the PTRACE_ATTACH retun -EAGAIN, instead of execve return -ERESTARTSYS. Added some lessions learned to the description. v11: Check old and new credentials in PTRACE_ATTACH again without changing the API. Note: I got actually one response from an automatic checker to the v11 patch, https://lore.kernel.org/lkml/202107121344.wu68hEPF-lkp@intel.com/ which is complaining about: >> kernel/ptrace.c:425:26: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct cred const *old_cred @@ got struct cred const [noderef] __rcu *real_cred @@ 417 struct linux_binprm *bprm = task->signal->exec_bprm; 418 const struct cred *old_cred; 419 struct mm_struct *old_mm; 420 421 retval = down_write_killable(&task->signal->exec_update_lock); 422 if (retval) 423 goto unlock_creds; 424 task_lock(task); > 425 old_cred = task->real_cred; v12: Essentially identical to v11. - Fixed a minor merge conflict in linux v5.17, and fixed the above mentioned nit by adding __rcu to the declaration. - re-tested the patch with all linux versions from v5.11 to v6.6 v10 was an alternative approach which did imply an API change. But I would prefer to avoid such an API change. The difficult part is getting the right dumpability flags assigned before de_thread starts, hope you like this version. If not, the v10 is of course also acceptable. Thanks Bernd. diff --git a/fs/exec.c b/fs/exec.c index 2f2b0acec4f0..902d3b230485 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1041,11 +1041,13 @@ static int exec_mmap(struct mm_struct *mm) return 0; } -static int de_thread(struct task_struct *tsk) +static int de_thread(struct task_struct *tsk, struct linux_binprm *bprm) { struct signal_struct *sig = tsk->signal; struct sighand_struct *oldsighand = tsk->sighand; spinlock_t *lock = &oldsighand->siglock; + struct task_struct *t = tsk; + bool unsafe_execve_in_progress = false; if (thread_group_empty(tsk)) goto no_thread_group; @@ -1068,6 +1070,19 @@ static int de_thread(struct task_struct *tsk) if (!thread_group_leader(tsk)) sig->notify_count--; + while_each_thread(tsk, t) { + if (unlikely(t->ptrace) + && (t != tsk->group_leader || !t->exit_state)) + unsafe_execve_in_progress = true; + } + + if (unlikely(unsafe_execve_in_progress)) { + spin_unlock_irq(lock); + sig->exec_bprm = bprm; + mutex_unlock(&sig->cred_guard_mutex); + spin_lock_irq(lock); + } + while (sig->notify_count) { __set_current_state(TASK_KILLABLE); spin_unlock_irq(lock); @@ -1158,6 +1173,11 @@ static int de_thread(struct task_struct *tsk) release_task(leader); } + if (unlikely(unsafe_execve_in_progress)) { + mutex_lock(&sig->cred_guard_mutex); + sig->exec_bprm = NULL; + } + sig->group_exec_task = NULL; sig->notify_count = 0; @@ -1169,6 +1189,11 @@ static int de_thread(struct task_struct *tsk) return 0; killed: + if (unlikely(unsafe_execve_in_progress)) { + mutex_lock(&sig->cred_guard_mutex); + sig->exec_bprm = NULL; + } + /* protects against exit_notify() and __exit_signal() */ read_lock(&tasklist_lock); sig->group_exec_task = NULL; @@ -1253,6 +1278,24 @@ int begin_new_exec(struct linux_binprm * bprm) if (retval) return retval; + /* If the binary is not readable then enforce mm->dumpable=0 */ + would_dump(bprm, bprm->file); + if (bprm->have_execfd) + would_dump(bprm, bprm->executable); + + /* + * Figure out dumpability. Note that this checking only of current + * is wrong, but userspace depends on it. This should be testing + * bprm->secureexec instead. + */ + if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP || + is_dumpability_changed(current_cred(), bprm->cred) || + !(uid_eq(current_euid(), current_uid()) && + gid_eq(current_egid(), current_gid()))) + set_dumpable(bprm->mm, suid_dumpable); + else + set_dumpable(bprm->mm, SUID_DUMP_USER); + /* * Ensure all future errors are fatal. */ @@ -1261,7 +1304,7 @@ int begin_new_exec(struct linux_binprm * bprm) /* * Make this the only thread in the thread group. */ - retval = de_thread(me); + retval = de_thread(me, bprm); if (retval) goto out; @@ -1284,11 +1327,6 @@ int begin_new_exec(struct linux_binprm * bprm) if (retval) goto out; - /* If the binary is not readable then enforce mm->dumpable=0 */ - would_dump(bprm, bprm->file); - if (bprm->have_execfd) - would_dump(bprm, bprm->executable); - /* * Release all of the old mmap stuff */ @@ -1350,18 +1388,6 @@ int begin_new_exec(struct linux_binprm * bprm) me->sas_ss_sp = me->sas_ss_size = 0; - /* - * Figure out dumpability. Note that this checking only of current - * is wrong, but userspace depends on it. This should be testing - * bprm->secureexec instead. - */ - if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP || - !(uid_eq(current_euid(), current_uid()) && - gid_eq(current_egid(), current_gid()))) - set_dumpable(current->mm, suid_dumpable); - else - set_dumpable(current->mm, SUID_DUMP_USER); - perf_event_exec(); __set_task_comm(me, kbasename(bprm->filename), true); @@ -1480,6 +1506,11 @@ static int prepare_bprm_creds(struct linux_binprm *bprm) if (mutex_lock_interruptible(&current->signal->cred_guard_mutex)) return -ERESTARTNOINTR; + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + return -ERESTARTNOINTR; + } + bprm->cred = prepare_exec_creds(); if (likely(bprm->cred)) return 0; diff --git a/fs/proc/base.c b/fs/proc/base.c index ffd54617c354..0da9adfadb48 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2788,6 +2788,12 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf, if (rv < 0) goto out_free; + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + rv = -ERESTARTNOINTR; + goto out_free; + } + rv = security_setprocattr(PROC_I(inode)->op.lsm, file->f_path.dentry->d_name.name, page, count); diff --git a/include/linux/cred.h b/include/linux/cred.h index f923528d5cc4..b01e309f5686 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -159,6 +159,7 @@ extern const struct cred *get_task_cred(struct task_struct *); extern struct cred *cred_alloc_blank(void); extern struct cred *prepare_creds(void); extern struct cred *prepare_exec_creds(void); +extern bool is_dumpability_changed(const struct cred *, const struct cred *); extern int commit_creds(struct cred *); extern void abort_creds(struct cred *); extern const struct cred *override_creds(const struct cred *); diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 0014d3adaf84..14df7073a0a8 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -234,9 +234,27 @@ struct signal_struct { struct mm_struct *oom_mm; /* recorded mm when the thread group got * killed by the oom killer */ + struct linux_binprm *exec_bprm; /* Used to check ptrace_may_access + * against new credentials while + * de_thread is waiting for other + * traced threads to terminate. + * Set while de_thread is executing. + * The cred_guard_mutex is released + * after de_thread() has called + * zap_other_threads(), therefore + * a fatal signal is guaranteed to be + * already pending in the unlikely + * event, that + * current->signal->exec_bprm happens + * to be non-zero after the + * cred_guard_mutex was acquired. + */ + struct mutex cred_guard_mutex; /* guard against foreign influences on * credential calculations * (notably. ptrace) + * Held while execve runs, except when + * a sibling thread is being traced. * Deprecated do not use in new code. * Use exec_update_lock instead. */ diff --git a/kernel/cred.c b/kernel/cred.c index 98cb4eca23fb..586cb6c7cf6b 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -433,6 +433,28 @@ static bool cred_cap_issubset(const struct cred *set, const struct cred *subset) return false; } +/** + * is_dumpability_changed - Will changing creds from old to new + * affect the dumpability in commit_creds? + * + * Return: false - dumpability will not be changed in commit_creds. + * Return: true - dumpability will be changed to non-dumpable. + * + * @old: The old credentials + * @new: The new credentials + */ +bool is_dumpability_changed(const struct cred *old, const struct cred *new) +{ + if (!uid_eq(old->euid, new->euid) || + !gid_eq(old->egid, new->egid) || + !uid_eq(old->fsuid, new->fsuid) || + !gid_eq(old->fsgid, new->fsgid) || + !cred_cap_issubset(old, new)) + return true; + + return false; +} + /** * commit_creds - Install new credentials upon the current task * @new: The credentials to be assigned @@ -467,11 +489,7 @@ int commit_creds(struct cred *new) get_cred(new); /* we will require a ref for the subj creds too */ /* dumpability changes */ - if (!uid_eq(old->euid, new->euid) || - !gid_eq(old->egid, new->egid) || - !uid_eq(old->fsuid, new->fsuid) || - !gid_eq(old->fsgid, new->fsgid) || - !cred_cap_issubset(old, new)) { + if (is_dumpability_changed(old, new)) { if (task->mm) set_dumpable(task->mm, suid_dumpable); task->pdeath_signal = 0; diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 443057bee87c..eb1c450bb7d7 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -20,6 +20,7 @@ #include <linux/pagemap.h> #include <linux/ptrace.h> #include <linux/security.h> +#include <linux/binfmts.h> #include <linux/signal.h> #include <linux/uio.h> #include <linux/audit.h> @@ -435,6 +436,28 @@ static int ptrace_attach(struct task_struct *task, long request, if (retval) goto unlock_creds; + if (unlikely(task->in_execve)) { + struct linux_binprm *bprm = task->signal->exec_bprm; + const struct cred __rcu *old_cred; + struct mm_struct *old_mm; + + retval = down_write_killable(&task->signal->exec_update_lock); + if (retval) + goto unlock_creds; + task_lock(task); + old_cred = task->real_cred; + old_mm = task->mm; + rcu_assign_pointer(task->real_cred, bprm->cred); + task->mm = bprm->mm; + retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS); + rcu_assign_pointer(task->real_cred, old_cred); + task->mm = old_mm; + task_unlock(task); + up_write(&task->signal->exec_update_lock); + if (retval) + goto unlock_creds; + } + write_lock_irq(&tasklist_lock); retval = -EPERM; if (unlikely(task->exit_state)) @@ -508,6 +531,14 @@ static int ptrace_traceme(void) { int ret = -EPERM; + if (mutex_lock_interruptible(&current->signal->cred_guard_mutex)) + return -ERESTARTNOINTR; + + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + return -ERESTARTNOINTR; + } + write_lock_irq(&tasklist_lock); /* Are we already being traced? */ if (!current->ptrace) { @@ -523,6 +554,7 @@ static int ptrace_traceme(void) } } write_unlock_irq(&tasklist_lock); + mutex_unlock(&current->signal->cred_guard_mutex); return ret; } diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 255999ba9190..b29bbfa0b044 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -1955,9 +1955,15 @@ static long seccomp_set_mode_filter(unsigned int flags, * Make sure we cannot change seccomp or nnp state via TSYNC * while another thread is in the middle of calling exec. */ - if (flags & SECCOMP_FILTER_FLAG_TSYNC && - mutex_lock_killable(&current->signal->cred_guard_mutex)) - goto out_put_fd; + if (flags & SECCOMP_FILTER_FLAG_TSYNC) { + if (mutex_lock_killable(&current->signal->cred_guard_mutex)) + goto out_put_fd; + + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + goto out_put_fd; + } + } spin_lock_irq(&current->sighand->siglock); diff --git a/tools/testing/selftests/ptrace/vmaccess.c b/tools/testing/selftests/ptrace/vmaccess.c index 4db327b44586..3b7d81fb99bb 100644 --- a/tools/testing/selftests/ptrace/vmaccess.c +++ b/tools/testing/selftests/ptrace/vmaccess.c @@ -39,8 +39,15 @@ TEST(vmaccess) f = open(mm, O_RDONLY); ASSERT_GE(f, 0); close(f); - f = kill(pid, SIGCONT); - ASSERT_EQ(f, 0); + f = waitpid(-1, NULL, 0); + ASSERT_NE(f, -1); + ASSERT_NE(f, 0); + ASSERT_NE(f, pid); + f = waitpid(-1, NULL, 0); + ASSERT_EQ(f, pid); + f = waitpid(-1, NULL, 0); + ASSERT_EQ(f, -1); + ASSERT_EQ(errno, ECHILD); } TEST(attach) @@ -57,22 +64,24 @@ TEST(attach) sleep(1); k = ptrace(PTRACE_ATTACH, pid, 0L, 0L); - ASSERT_EQ(errno, EAGAIN); - ASSERT_EQ(k, -1); + ASSERT_EQ(k, 0); k = waitpid(-1, &s, WNOHANG); ASSERT_NE(k, -1); ASSERT_NE(k, 0); ASSERT_NE(k, pid); ASSERT_EQ(WIFEXITED(s), 1); ASSERT_EQ(WEXITSTATUS(s), 0); - sleep(1); - k = ptrace(PTRACE_ATTACH, pid, 0L, 0L); + k = waitpid(-1, &s, 0); + ASSERT_EQ(k, pid); + ASSERT_EQ(WIFSTOPPED(s), 1); + ASSERT_EQ(WSTOPSIG(s), SIGTRAP); + k = ptrace(PTRACE_CONT, pid, 0L, 0L); ASSERT_EQ(k, 0); k = waitpid(-1, &s, 0); ASSERT_EQ(k, pid); ASSERT_EQ(WIFSTOPPED(s), 1); ASSERT_EQ(WSTOPSIG(s), SIGSTOP); - k = ptrace(PTRACE_DETACH, pid, 0L, 0L); + k = ptrace(PTRACE_CONT, pid, 0L, 0L); ASSERT_EQ(k, 0); k = waitpid(-1, &s, 0); ASSERT_EQ(k, pid); -- 2.39.2

2 days, 22 hours

8
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[PATCH 00/32] ns: support file handles

by Christian Brauner

For a while now we have supported file handles for pidfds. This has proven to be very useful. Extend the concept to cover namespaces as well. After this patchset it is possible to encode and decode namespace file handles using the commong name_to_handle_at() and open_by_handle_at() apis. Namespaces file descriptors can already be derived from pidfds which means they aren't subject to overmount protection bugs. IOW, it's irrelevant if the caller would not have access to an appropriate /proc/<pid>/ns/ directory as they could always just derive the namespace based on a pidfd already. It has the same advantage as pidfds. It's possible to reliably and for the lifetime of the system refer to a namespace without pinning any resources and to compare them. Permission checking is kept simple. If the caller is located in the namespace the file handle refers to they are able to open it otherwise they must hold privilege over the owning namespace of the relevant namespace. Both the network namespace and the mount namespace already have an associated cookie that isn't recycled and is fully exposed to userspace. Move this into ns_common and use the same id space for all namespaces so they can trivially and reliably be compared. There's more coming based on the iterator infrastructure but the series is large enough and focuses on file handles. Extensive selftests included. I still have various other test-suites to run but it holds up so far. Signed-off-by: Christian Brauner <brauner(a)kernel.org> --- Christian Brauner (32): pidfs: validate extensible ioctls nsfs: validate extensible ioctls block: use extensible_ioctl_valid() ns: move to_ns_common() to ns_common.h nsfs: add nsfs.h header ns: uniformly initialize ns_common mnt: use ns_common_init() ipc: use ns_common_init() cgroup: use ns_common_init() pid: use ns_common_init() time: use ns_common_init() uts: use ns_common_init() user: use ns_common_init() net: use ns_common_init() ns: remove ns_alloc_inum() nstree: make iterator generic mnt: support iterator cgroup: support iterator ipc: support iterator net: support iterator pid: support iterator time: support iterator userns: support iterator uts: support iterator ns: add to_<type>_ns() to respective headers nsfs: add current_in_namespace() nsfs: support file handles nsfs: support exhaustive file handles nsfs: add missing id retrieval support tools: update nsfs.h uapi header selftests/namespaces: add identifier selftests selftests/namespaces: add file handle selftests block/blk-integrity.c | 8 +- fs/fhandle.c | 6 + fs/internal.h | 1 + fs/mount.h | 10 +- fs/namespace.c | 156 +-- fs/nsfs.c | 266 +++- fs/pidfs.c | 2 +- include/linux/cgroup.h | 5 + include/linux/exportfs.h | 6 + include/linux/fs.h | 14 + include/linux/ipc_namespace.h | 5 + include/linux/ns_common.h | 29 + include/linux/nsfs.h | 40 + include/linux/nsproxy.h | 11 - include/linux/nstree.h | 89 ++ include/linux/pid_namespace.h | 5 + include/linux/proc_ns.h | 32 +- include/linux/time_namespace.h | 9 + include/linux/user_namespace.h | 5 + include/linux/utsname.h | 5 + include/net/net_namespace.h | 6 + include/uapi/linux/fcntl.h | 1 + include/uapi/linux/nsfs.h | 12 +- init/main.c | 2 + ipc/msgutil.c | 1 + ipc/namespace.c | 12 +- ipc/shm.c | 2 + kernel/Makefile | 2 +- kernel/cgroup/cgroup.c | 2 + kernel/cgroup/namespace.c | 24 +- kernel/nstree.c | 233 ++++ kernel/pid_namespace.c | 13 +- kernel/time/namespace.c | 23 +- kernel/user_namespace.c | 17 +- kernel/utsname.c | 28 +- net/core/net_namespace.c | 59 +- tools/include/uapi/linux/nsfs.h | 23 +- tools/testing/selftests/namespaces/.gitignore | 2 + tools/testing/selftests/namespaces/Makefile | 7 + tools/testing/selftests/namespaces/config | 7 + .../selftests/namespaces/file_handle_test.c | 1410 ++++++++++++++++++++ tools/testing/selftests/namespaces/nsid_test.c | 986 ++++++++++++++ 42 files changed, 3306 insertions(+), 270 deletions(-) --- base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585 change-id: 20250905-work-namespace-c68826dda0d4

5 days, 12 hours

12
77
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[PATCH v1] selftests: cachestat: Fix warning on declaration under label

by Sidharth Seela

Fix warning caused from declaration under a case label. The proper way is to declare variable at the beginning of the function. The warning came from running clang using LLVM=1; and is as follows: -- -test_cachestat.c:260:3: warning: label followed by a declaration is a C23 extension [-Wc23-extensions] 260 | char *map = mmap(NULL, filesize, PROT_READ | PROT_WRITE, | Signed-off-by: Sidharth Seela <sidharthseela(a)gmail.com> --- diff --git a/tools/testing/selftests/cachestat/test_cachestat.c b/tools/testing/selftests/cachestat/test_cachestat.c index c952640f163b..0305e736f2b8 100644 --- a/tools/testing/selftests/cachestat/test_cachestat.c +++ b/tools/testing/selftests/cachestat/test_cachestat.c @@ -226,7 +226,7 @@ bool run_cachestat_test(enum file_type type) int syscall_ret; size_t compute_len = PS * 512; struct cachestat_range cs_range = { PS, compute_len }; - char *filename = "tmpshmcstat"; + char *filename = "tmpshmcstat", *map; struct cachestat cs; bool ret = true; int fd; @@ -257,7 +257,7 @@ bool run_cachestat_test(enum file_type type) } break; case FILE_MMAP: - char *map = mmap(NULL, filesize, PROT_READ | PROT_WRITE, + map = mmap(NULL, filesize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (map == MAP_FAILED) { -- 2.47.3

6 days, 19 hours

6
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[PATCH 0/4] KVM: selftests: Add test of SET_NESTED_STATE with 48-bit L2 on 57-bit L1

by Jim Mattson

Prior to commit 9245fd6b8531 ("KVM: x86: model canonical checks more precisely"), KVM_SET_NESTED_STATE would fail if the state was captured with L2 active, L1 had CR4.LA57 set, L2 did not, and the VMCS12.HOST_GSBASE (or other host-state field checked for canonicality) had an address greater than 48 bits wide. Add a regression test that reproduces the KVM_SET_NESTED_STATE failure conditions. To do so, the first three patches add support for 5-level paging in the selftest L1 VM. Jim Mattson (4): KVM: selftests: Use a loop to create guest page tables KVM: selftests: Use a loop to walk guest page tables KVM: selftests: Add VM_MODE_PXXV57_4K VM mode KVM: selftests: Add a VMX test for LA57 nested state tools/testing/selftests/kvm/Makefile.kvm | 1 + .../testing/selftests/kvm/include/kvm_util.h | 1 + tools/testing/selftests/kvm/lib/kvm_util.c | 21 +++ .../testing/selftests/kvm/lib/x86/processor.c | 66 ++++----- tools/testing/selftests/kvm/lib/x86/vmx.c | 7 +- .../kvm/x86/vmx_la57_nested_state_test.c | 137 ++++++++++++++++++ 6 files changed, 195 insertions(+), 38 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86/vmx_la57_nested_state_test.c -- 2.51.0.470.ga7dc726c21-goog

1 week

3
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[RFC PATCH v2 0/3] Add testable code specifications

by Gabriele Paoloni

[1] was an initial proposal defining testable code specifications for some functions in /drivers/char/mem.c. However a Guideline to write such specifications was missing and test cases tracing to such specifications were missing. This patchset represents a next step and is organised as follows: - patch 1/3 contains the Guideline for writing code specifications - patch 2/3 contains examples of code specfications defined for some functions of drivers/char/mem.c - patch 3/3 contains examples of selftests that map to some code specifications of patch 2/3 [1] https://lore.kernel.org/all/20250821170419.70668-1-gpaoloni@redhat.com/ --- Changes from v1: 1) Added a Guideline to write code specifications in the Linux Kernel Documentation 2) Addressed Greg KH comments in /drivers/char/mem.c 3) Added example of test cases mapping to the code specifications in /drivers/char/mem.c --- Alessandro Carminati (1): selftests/devmem: initial testset Gabriele Paoloni (2): Documentation: add guidelines for writing testable code specifications /dev/mem: Add initial documentation of memory_open() and mem_fops .../doc-guide/code-specifications.rst | 208 +++++++ Documentation/doc-guide/index.rst | 1 + drivers/char/mem.c | 231 ++++++- tools/testing/selftests/Makefile | 1 + tools/testing/selftests/devmem/Makefile | 13 + tools/testing/selftests/devmem/debug.c | 25 + tools/testing/selftests/devmem/debug.h | 14 + tools/testing/selftests/devmem/devmem.c | 200 ++++++ tools/testing/selftests/devmem/ram_map.c | 250 ++++++++ tools/testing/selftests/devmem/ram_map.h | 38 ++ tools/testing/selftests/devmem/secret.c | 46 ++ tools/testing/selftests/devmem/secret.h | 13 + tools/testing/selftests/devmem/tests.c | 569 ++++++++++++++++++ tools/testing/selftests/devmem/tests.h | 45 ++ tools/testing/selftests/devmem/utils.c | 379 ++++++++++++ tools/testing/selftests/devmem/utils.h | 119 ++++ 16 files changed, 2146 insertions(+), 6 deletions(-) create mode 100644 Documentation/doc-guide/code-specifications.rst create mode 100644 tools/testing/selftests/devmem/Makefile create mode 100644 tools/testing/selftests/devmem/debug.c create mode 100644 tools/testing/selftests/devmem/debug.h create mode 100644 tools/testing/selftests/devmem/devmem.c create mode 100644 tools/testing/selftests/devmem/ram_map.c create mode 100644 tools/testing/selftests/devmem/ram_map.h create mode 100644 tools/testing/selftests/devmem/secret.c create mode 100644 tools/testing/selftests/devmem/secret.h create mode 100644 tools/testing/selftests/devmem/tests.c create mode 100644 tools/testing/selftests/devmem/tests.h create mode 100644 tools/testing/selftests/devmem/utils.c create mode 100644 tools/testing/selftests/devmem/utils.h -- 2.48.1

1 week

7
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[PATCH v4 00/23] ARM64 PMU Partitioning

by Colton Lewis

This series creates a new PMU scheme on ARM, a partitioned PMU that allows reserving a subset of counters for more direct guest access, significantly reducing overhead. More details, including performance benchmarks, can be read in the v1 cover letter linked below. v4: * Apply Mark Brown's non-UNDEF FGT control commit to the PMU FGT controls and calculate those controls with the others in kvm_calculate_traps() * Introduce lazy context swaps for guests that only turns on for guests that have enabled partitioning and accessed PMU registers. * Rename pmu-part.c to pmu-direct.c because future features might achieve direct PMU access without partitioning. * Better explain certain commits, such as why the untrapped registers are safe to untrap. * Reduce the PMU include cleanup down to only what is still necessary and explain why. v3: https://lore.kernel.org/kvm/20250626200459.1153955-1-coltonlewis@google.com/ v2: https://lore.kernel.org/kvm/20250620221326.1261128-1-coltonlewis@google.com/ v1: https://lore.kernel.org/kvm/20250602192702.2125115-1-coltonlewis@google.com/ Colton Lewis (21): arm64: cpufeature: Add cpucap for HPMN0 KVM: arm64: Reorganize PMU functions perf: arm_pmuv3: Introduce method to partition the PMU perf: arm_pmuv3: Generalize counter bitmasks perf: arm_pmuv3: Keep out of guest counter partition KVM: arm64: Account for partitioning in kvm_pmu_get_max_counters() KVM: arm64: Set up FGT for Partitioned PMU KVM: arm64: Writethrough trapped PMEVTYPER register KVM: arm64: Use physical PMSELR for PMXEVTYPER if partitioned KVM: arm64: Writethrough trapped PMOVS register KVM: arm64: Write fast path PMU register handlers KVM: arm64: Setup MDCR_EL2 to handle a partitioned PMU KVM: arm64: Account for partitioning in PMCR_EL0 access KVM: arm64: Context swap Partitioned PMU guest registers KVM: arm64: Enforce PMU event filter at vcpu_load() KVM: arm64: Extract enum debug_owner to enum vcpu_register_owner KVM: arm64: Implement lazy PMU context swaps perf: arm_pmuv3: Handle IRQs for Partitioned PMU guest counters KVM: arm64: Inject recorded guest interrupts KVM: arm64: Add ioctl to partition the PMU when supported KVM: arm64: selftests: Add test case for partitioned PMU Marc Zyngier (1): KVM: arm64: Reorganize PMU includes Mark Brown (1): KVM: arm64: Introduce non-UNDEF FGT control Documentation/virt/kvm/api.rst | 21 + arch/arm/include/asm/arm_pmuv3.h | 38 + arch/arm64/include/asm/arm_pmuv3.h | 61 +- arch/arm64/include/asm/kvm_host.h | 34 +- arch/arm64/include/asm/kvm_pmu.h | 123 +++ arch/arm64/include/asm/kvm_types.h | 7 +- arch/arm64/kernel/cpufeature.c | 8 + arch/arm64/kvm/Makefile | 2 +- arch/arm64/kvm/arm.c | 22 + arch/arm64/kvm/debug.c | 33 +- arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 6 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 181 ++++- arch/arm64/kvm/pmu-direct.c | 395 ++++++++++ arch/arm64/kvm/pmu-emul.c | 674 +--------------- arch/arm64/kvm/pmu.c | 725 ++++++++++++++++++ arch/arm64/kvm/sys_regs.c | 137 +++- arch/arm64/tools/cpucaps | 1 + arch/arm64/tools/sysreg | 6 +- drivers/perf/arm_pmuv3.c | 128 +++- include/linux/perf/arm_pmu.h | 1 + include/linux/perf/arm_pmuv3.h | 14 +- include/uapi/linux/kvm.h | 4 + tools/include/uapi/linux/kvm.h | 2 + .../selftests/kvm/arm64/vpmu_counter_access.c | 62 +- 24 files changed, 1910 insertions(+), 775 deletions(-) create mode 100644 arch/arm64/kvm/pmu-direct.c base-commit: 79150772457f4d45e38b842d786240c36bb1f97f -- 2.50.0.727.gbf7dc18ff4-goog

1 week

3
31
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[PATCH nf-next v6 0/2] Add IPIP flowtable SW acceleratio

by Lorenzo Bianconi

Introduce SW acceleration for IPIP tunnels in the netfilter flowtable infrastructure. --- Changes in v6: - Rebase on top of nf-next main branch - Link to v5: https://lore.kernel.org/r/20250721-nf-flowtable-ipip-v5-0-0865af9e58c6@kern… Changes in v5: - Rely on __ipv4_addr_hash() to compute the hash used as encap ID - Remove unnecessary pskb_may_pull() in nf_flow_tuple_encap() - Add nf_flow_ip4_ecanp_pop utility routine - Link to v4: https://lore.kernel.org/r/20250718-nf-flowtable-ipip-v4-0-f8bb1c18b986@kern… Changes in v4: - Use the hash value of the saddr, daddr and protocol of outer IP header as encapsulation id. - Link to v3: https://lore.kernel.org/r/20250703-nf-flowtable-ipip-v3-0-880afd319b9f@kern… Changes in v3: - Add outer IP header sanity checks - target nf-next tree instead of net-next - Link to v2: https://lore.kernel.org/r/20250627-nf-flowtable-ipip-v2-0-c713003ce75b@kern… Changes in v2: - Introduce IPIP flowtable selftest - Link to v1: https://lore.kernel.org/r/20250623-nf-flowtable-ipip-v1-1-2853596e3941@kern… --- Lorenzo Bianconi (2): net: netfilter: Add IPIP flowtable SW acceleration selftests: netfilter: nft_flowtable.sh: Add IPIP flowtable selftest include/linux/netdevice.h | 1 + net/ipv4/ipip.c | 28 +++++++++++ net/netfilter/nf_flow_table_ip.c | 56 +++++++++++++++++++++- net/netfilter/nft_flow_offload.c | 1 + .../selftests/net/netfilter/nft_flowtable.sh | 40 ++++++++++++++++ 5 files changed, 124 insertions(+), 2 deletions(-) --- base-commit: bab3ce404553de56242d7b09ad7ea5b70441ea41 change-id: 20250623-nf-flowtable-ipip-1b3d7b08d067 Best regards, -- Lorenzo Bianconi <lorenzo(a)kernel.org>

1 week, 1 day

2
5
0 0

[PATCH kvm-next V11 0/7] Add NUMA mempolicy support for KVM guest-memfd

by Shivank Garg

This series introduces NUMA-aware memory placement support for KVM guests with guest_memfd memory backends. It builds upon Fuad Tabba's work (V17) that enabled host-mapping for guest_memfd memory [1] and can be applied directly applied on KVM tree [2] (branch kvm-next, base commit: a6ad5413, Merge branch 'guest-memfd-mmap' into HEAD) == Background == KVM's guest-memfd memory backend currently lacks support for NUMA policy enforcement, causing guest memory allocations to be distributed across host nodes according to kernel's default behavior, irrespective of any policy specified by the VMM. This limitation arises because conventional userspace NUMA control mechanisms like mbind(2) don't work since the memory isn't directly mapped to userspace when allocations occur. Fuad's work [1] provides the necessary mmap capability, and this series leverages it to enable mbind(2). == Implementation == This series implements proper NUMA policy support for guest-memfd by: 1. Adding mempolicy-aware allocation APIs to the filemap layer. 2. Introducing custom inodes (via a dedicated slab-allocated inode cache, kvm_gmem_inode_info) to store NUMA policy and metadata for guest memory. 3. Implementing get/set_policy vm_ops in guest_memfd to support NUMA policy. With these changes, VMMs can now control guest memory placement by mapping guest_memfd file descriptor and using mbind(2) to specify: - Policy modes: default, bind, interleave, or preferred - Host NUMA nodes: List of target nodes for memory allocation These Policies affect only future allocations and do not migrate existing memory. This matches mbind(2)'s default behavior which affects only new allocations unless overridden with MPOL_MF_MOVE/MPOL_MF_MOVE_ALL flags (Not supported for guest_memfd as it is unmovable by design). == Upstream Plan == Phased approach as per David's guest_memfd extension overview [3] and community calls [4]: Phase 1 (this series): 1. Focuses on shared guest_memfd support (non-CoCo VMs). 2. Builds on Fuad's host-mapping work [1]. Phase2 (future work): 1. NUMA support for private guest_memfd (CoCo VMs). 2. Depends on SNP in-place conversion support [5]. This series provides a clean integration path for NUMA-aware memory management for guest_memfd and lays the groundwork for future confidential computing NUMA capabilities. Thanks, Shivank == Changelog == - v1,v2: Extended the KVM_CREATE_GUEST_MEMFD IOCTL to pass mempolicy. - v3: Introduced fbind() syscall for VMM memory-placement configuration. - v4-v6: Current approach using shared_policy support and vm_ops (based on suggestions from David [6] and guest_memfd bi-weekly upstream call discussion [7]). - v7: Use inodes to store NUMA policy instead of file [8]. - v8: Rebase on top of Fuad's V12: Host mmaping for guest_memfd memory. - v9: Rebase on top of Fuad's V13 and incorporate review comments - V10: Rebase on top of Fuad's V17. Use latest guest_memfd inode patch from Ackerley (with David's review comments). Use newer kmem_cache_create() API variant with arg parameter (Vlastimil) - V11: Rebase on kvm-next, remove RFC tag, use Ackerley's latest patch and fix a rcu race bug during kvm module unload. [1] https://lore.kernel.org/all/20250729225455.670324-1-seanjc@google.com [2] https://git.kernel.org/pub/scm/virt/kvm/kvm.git/log/?h=next [3] https://lore.kernel.org/all/c1c9591d-218a-495c-957b-ba356c8f8e09@redhat.com [4] https://docs.google.com/document/d/1M6766BzdY1Lhk7LiR5IqVR8B8mG3cr-cxTxOrAo… [5] https://lore.kernel.org/all/20250613005400.3694904-1-michael.roth@amd.com [6] https://lore.kernel.org/all/6fbef654-36e2-4be5-906e-2a648a845278@redhat.com [7] https://lore.kernel.org/all/2b77e055-98ac-43a1-a7ad-9f9065d7f38f@amd.com [8] https://lore.kernel.org/all/diqzbjumm167.fsf@ackerleytng-ctop.c.googlers.com Ackerley Tng (1): KVM: guest_memfd: Use guest mem inodes instead of anonymous inodes Matthew Wilcox (Oracle) (2): mm/filemap: Add NUMA mempolicy support to filemap_alloc_folio() mm/filemap: Extend __filemap_get_folio() to support NUMA memory policies Shivank Garg (4): mm/mempolicy: Export memory policy symbols KVM: guest_memfd: Add slab-allocated inode cache KVM: guest_memfd: Enforce NUMA mempolicy using shared policy KVM: guest_memfd: selftests: Add tests for mmap and NUMA policy support fs/bcachefs/fs-io-buffered.c | 2 +- fs/btrfs/compression.c | 4 +- fs/btrfs/verity.c | 2 +- fs/erofs/zdata.c | 2 +- fs/f2fs/compress.c | 2 +- include/linux/pagemap.h | 18 +- include/uapi/linux/magic.h | 1 + mm/filemap.c | 23 +- mm/mempolicy.c | 6 + mm/readahead.c | 2 +- tools/testing/selftests/kvm/Makefile.kvm | 1 + .../testing/selftests/kvm/guest_memfd_test.c | 121 ++++++++ virt/kvm/guest_memfd.c | 262 ++++++++++++++++-- virt/kvm/kvm_main.c | 7 +- virt/kvm/kvm_mm.h | 9 +- 15 files changed, 412 insertions(+), 50 deletions(-) -- 2.43.0 --- == Earlier Postings == v10: https://lore.kernel.org/all/20250811090605.16057-2-shivankg@amd.com v9: https://lore.kernel.org/all/20250713174339.13981-2-shivankg@amd.com v8: https://lore.kernel.org/all/20250618112935.7629-1-shivankg@amd.com v7: https://lore.kernel.org/all/20250408112402.181574-1-shivankg@amd.com v6: https://lore.kernel.org/all/20250226082549.6034-1-shivankg@amd.com v5: https://lore.kernel.org/all/20250219101559.414878-1-shivankg@amd.com v4: https://lore.kernel.org/all/20250210063227.41125-1-shivankg@amd.com v3: https://lore.kernel.org/all/20241105164549.154700-1-shivankg@amd.com v2: https://lore.kernel.org/all/20240919094438.10987-1-shivankg@amd.com v1: https://lore.kernel.org/all/20240916165743.201087-1-shivankg@amd.com

1 week, 2 days

9
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Linux-kselftest-mirror September 2025