August 2024 - Linux-kselftest-mirror

[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, 20 hours

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[PATCH v2 00/19] iommufd: Add VIOMMU infrastructure (Part-1)

by Nicolin Chen

This series introduces a new VIOMMU infrastructure and related ioctls. IOMMUFD has been using the HWPT infrastructure for all cases, including a nested IO page table support. Yet, there're limitations for an HWPT-based structure to support some advanced HW-accelerated features, such as CMDQV on NVIDIA Grace, and HW-accelerated vIOMMU on AMD. Even for a multi-IOMMU environment, it is not straightforward for nested HWPTs to share the same parent HWPT (stage-2 IO pagetable), with the HWPT infrastructure alone. The new VIOMMU object is an additional layer, between the nested HWPT and its parent HWPT, to give to both the IOMMUFD core and an IOMMU driver an additional structure to support HW-accelerated feature: ---------------------------- ---------------- | | paging_hwpt0 | | hwpt_nested0 |--->| viommu0 ------------------ ---------------- | | HW-accel feats | ---------------------------- On a multi-IOMMU system, the VIOMMU object can be instanced to the number of vIOMMUs in a guest VM, while holding the same parent HWPT to share the stage-2 IO pagetable. Each VIOMMU then just need to only allocate its own VMID to attach the shared stage-2 IO pagetable to the physical IOMMU: ---------------------------- ---------------- | | paging_hwpt0 | | hwpt_nested0 |--->| viommu0 ------------------ ---------------- | | VMID0 | ---------------------------- ---------------------------- ---------------- | | paging_hwpt0 | | hwpt_nested1 |--->| viommu1 ------------------ ---------------- | | VMID1 | ---------------------------- As an initial part-1, add ioctls to support a VIOMMU-based invalidation: IOMMUFD_CMD_VIOMMU_ALLOC to allocate a VIOMMU object IOMMUFD_CMD_VIOMMU_SET/UNSET_VDEV_ID to set/clear device's virtual ID (Resue IOMMUFD_CMD_HWPT_INVALIDATE for a VIOMMU object to flush cache by a given driver data) Worth noting that the VDEV_ID is for a per-VIOMMU device list for drivers to look up the device's physical instance from its virtual ID in a VM. It is essential for a VIOMMU-based invalidation where the request contains a device's virtual ID for its device cache flush, e.g. ATC invalidation. As for the implementation of the series, add an IOMMU_VIOMMU_TYPE_DEFAULT type for a core-allocated-core-managed VIOMMU object, allowing drivers to simply hook a default viommu ops for viommu-based invalidation alone. And provide some viommu helpers to drivers for VDEV_ID translation and parent domain lookup. Add VIOMMU invalidation support to ARM SMMUv3 driver for a real world use case. This adds supports of arm-smmuv-v3's CMDQ_OP_ATC_INV and CMDQ_OP_CFGI_CD/ALL commands, supplementing HWPT-based invalidations. In the future, drivers will also be able to choose a driver-managed type to hold its own structure by adding a new type to enum iommu_viommu_type. More VIOMMU-based structures and ioctls will be introduced in part-2/3 to support a driver-managed VIOMMU, e.g. VQUEUE object for a HW accelerated queue, VIRQ (or VEVENT) object for IRQ injections. Although we repurposed the VIOMMU object from an earlier RFC discussion, for a referece: https://lore.kernel.org/all/cover.1712978212.git.nicolinc@nvidia.com/ This series is on Github: https://github.com/nicolinc/iommufd/commits/iommufd_viommu_p1-v2 Paring QEMU branch for testing: https://github.com/nicolinc/qemu/commits/wip/for_iommufd_viommu_p1-v2 Changelog v2 * Limited vdev_id to one per idev * Added a rw_sem to protect the vdev_id list * Reworked driver-level APIs with proper lockings * Added a new viommu_api file for IOMMUFD_DRIVER config * Dropped useless iommu_dev point from the viommu structure * Added missing index numnbers to new types in the uAPI header * Dropped IOMMU_VIOMMU_INVALIDATE uAPI; Instead, reuse the HWPT one * Reworked mock_viommu_cache_invalidate() using the new iommu helper * Reordered details of set/unset_vdev_id handlers for proper lockings * Added arm_smmu_cache_invalidate_user patch from Jason's nesting series v1 https://lore.kernel.org/all/cover.1723061377.git.nicolinc@nvidia.com/ Thanks! Nicolin Jason Gunthorpe (3): iommu: Add iommu_copy_struct_from_full_user_array helper iommu/arm-smmu-v3: Allow ATS for IOMMU_DOMAIN_NESTED iommu/arm-smmu-v3: Update comments about ATS and bypass Nicolin Chen (16): iommufd: Reorder struct forward declarations iommufd/viommu: Add IOMMUFD_OBJ_VIOMMU and IOMMU_VIOMMU_ALLOC ioctl iommu: Pass in a viommu pointer to domain_alloc_user op iommufd: Allow pt_id to carry viommu_id for IOMMU_HWPT_ALLOC iommufd/selftest: Add IOMMU_VIOMMU_ALLOC test coverage iommufd/viommu: Add IOMMU_VIOMMU_SET/UNSET_VDEV_ID ioctl iommufd/selftest: Add IOMMU_VIOMMU_SET/UNSET_VDEV_ID test coverage iommufd/viommu: Add cache_invalidate for IOMMU_VIOMMU_TYPE_DEFAULT iommufd: Allow hwpt_id to carry viommu_id for IOMMU_HWPT_INVALIDATE iommufd/viommu: Add vdev_id helpers for IOMMU drivers iommufd/selftest: Add mock_viommu_invalidate_user op iommufd/selftest: Add IOMMU_TEST_OP_DEV_CHECK_CACHE test command iommufd/selftest: Add VIOMMU coverage for IOMMU_HWPT_INVALIDATE ioctl iommufd/viommu: Add iommufd_viommu_to_parent_domain helper iommu/arm-smmu-v3: Add arm_smmu_cache_invalidate_user iommu/arm-smmu-v3: Add arm_smmu_viommu_cache_invalidate drivers/iommu/amd/iommu.c | 1 + drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 218 ++++++++++++++- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 3 + drivers/iommu/intel/iommu.c | 1 + drivers/iommu/iommufd/Makefile | 5 +- drivers/iommu/iommufd/device.c | 12 + drivers/iommu/iommufd/hw_pagetable.c | 59 +++- drivers/iommu/iommufd/iommufd_private.h | 37 +++ drivers/iommu/iommufd/iommufd_test.h | 30 ++ drivers/iommu/iommufd/main.c | 12 + drivers/iommu/iommufd/selftest.c | 101 ++++++- drivers/iommu/iommufd/viommu.c | 196 +++++++++++++ drivers/iommu/iommufd/viommu_api.c | 53 ++++ include/linux/iommu.h | 56 +++- include/linux/iommufd.h | 51 +++- include/uapi/linux/iommufd.h | 117 +++++++- tools/testing/selftests/iommu/iommufd.c | 259 +++++++++++++++++- tools/testing/selftests/iommu/iommufd_utils.h | 126 +++++++++ 18 files changed, 1299 insertions(+), 38 deletions(-) create mode 100644 drivers/iommu/iommufd/viommu.c create mode 100644 drivers/iommu/iommufd/viommu_api.c -- 2.43.0

3 months, 1 week

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[RFC PATCH 00/11] New KVM ioctl to link a gmem inode to a new gmem file

by Ackerley Tng

Hello, This patchset builds upon the code at https://lore.kernel.org/lkml/20230718234512.1690985-1-seanjc@google.com/T/. This code is available at https://github.com/googleprodkernel/linux-cc/tree/kvm-gmem-link-migrate-rfc…. In guest_mem v11, a split file/inode model was proposed, where memslot bindings belong to the file and pages belong to the inode. This model lends itself well to having different VMs use separate files pointing to the same inode. This RFC proposes an ioctl, KVM_LINK_GUEST_MEMFD, that takes a VM and a gmem fd, and returns another gmem fd referencing a different file and associated with VM. This RFC also includes an update to KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM to migrate memory context (slot->arch.lpage_info and kvm->mem_attr_array) from source to destination vm, intra-host. Intended usage of the two ioctls: 1. Source VM’s fd is passed to destination VM via unix sockets 2. Destination VM uses new ioctl KVM_LINK_GUEST_MEMFD to link source VM’s fd to a new fd. 3. Destination VM will pass new fds to KVM_SET_USER_MEMORY_REGION, which will bind the new file, pointing to the same inode that the source VM’s file points to, to memslots 4. Use KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM to move kvm->mem_attr_array and slot->arch.lpage_info to the destination VM. 5. Run the destination VM as per normal Some other approaches considered were: + Using the linkat() syscall, but that requires a mount/directory for a source fd to be linked to + Using the dup() syscall, but that only duplicates the fd, and both fds point to the same file --- Ackerley Tng (11): KVM: guest_mem: Refactor out kvm_gmem_alloc_file() KVM: guest_mem: Add ioctl KVM_LINK_GUEST_MEMFD KVM: selftests: Add tests for KVM_LINK_GUEST_MEMFD ioctl KVM: selftests: Test transferring private memory to another VM KVM: x86: Refactor sev's flag migration_in_progress to kvm struct KVM: x86: Refactor common code out of sev.c KVM: x86: Refactor common migration preparation code out of sev_vm_move_enc_context_from KVM: x86: Let moving encryption context be configurable KVM: x86: Handle moving of memory context for intra-host migration KVM: selftests: Generalize migration functions from sev_migrate_tests.c KVM: selftests: Add tests for migration of private mem arch/x86/include/asm/kvm_host.h | 4 +- arch/x86/kvm/svm/sev.c | 85 ++----- arch/x86/kvm/svm/svm.h | 3 +- arch/x86/kvm/x86.c | 221 +++++++++++++++++- arch/x86/kvm/x86.h | 6 + include/linux/kvm_host.h | 18 ++ include/uapi/linux/kvm.h | 8 + tools/testing/selftests/kvm/Makefile | 1 + .../testing/selftests/kvm/guest_memfd_test.c | 42 ++++ .../selftests/kvm/include/kvm_util_base.h | 31 +++ .../kvm/x86_64/private_mem_migrate_tests.c | 93 ++++++++ .../selftests/kvm/x86_64/sev_migrate_tests.c | 48 ++-- virt/kvm/guest_mem.c | 151 ++++++++++-- virt/kvm/kvm_main.c | 10 + virt/kvm/kvm_mm.h | 7 + 15 files changed, 596 insertions(+), 132 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86_64/private_mem_migrate_tests.c -- 2.41.0.640.ga95def55d0-goog

3 months, 2 weeks

3
15
0 0

[PATCH v6 0/5] userfaultfd move option

by Suren Baghdasaryan

This patch series introduces UFFDIO_MOVE feature to userfaultfd, which has long been implemented and maintained by Andrea in his local tree [1], but was not upstreamed due to lack of use cases where this approach would be better than allocating a new page and copying the contents. Previous upstraming attempts could be found at [6] and [7]. UFFDIO_COPY performs ~20% better than UFFDIO_MOVE when the application needs pages to be allocated [2]. However, with UFFDIO_MOVE, if pages are available (in userspace) for recycling, as is usually the case in heap compaction algorithms, then we can avoid the page allocation and memcpy (done by UFFDIO_COPY). Also, since the pages are recycled in the userspace, we avoid the need to release (via madvise) the pages back to the kernel [3]. We see over 40% reduction (on a Google pixel 6 device) in the compacting thread’s completion time by using UFFDIO_MOVE vs. UFFDIO_COPY. This was measured using a benchmark that emulates a heap compaction implementation using userfaultfd (to allow concurrent accesses by application threads). More details of the usecase are explained in [3]. Furthermore, UFFDIO_MOVE enables moving swapped-out pages without touching them within the same vma. Today, it can only be done by mremap, however it forces splitting the vma. TODOs for follow-up improvements: - cross-mm support. Known differences from single-mm and missing pieces: - memcg recharging (might need to isolate pages in the process) - mm counters - cross-mm deposit table moves - cross-mm test - document the address space where src and dest reside in struct uffdio_move - TLB flush batching. Will require extensive changes to PTL locking in move_pages_pte(). OTOH that might let us reuse parts of mremap code. Changes since v5 [10]: - added logic to split large folios in move_pages_pte(), per David Hildenbrand - added check for PAE before split_huge_pmd() to avoid the split if the move operation can't be done - replaced calls to default_huge_page_size() with read_pmd_pagesize() in uffd_move_pmd test, per David Hildenbrand - fixed the condition in uffd_move_test_common() checking if area alignment is needed Changes since v4 [9]: - added Acked-by in patch 1, per Peter Xu - added description for ctx, mm and mode parameters of move_pages(), per kernel test robot - added Reviewed-by's, per Peter Xu and Axel Rasmussen - removed unused operations in uffd_test_case_ops - refactored uffd-unit-test changes to avoid using global variables and handle pmd moves without page size overrides, per Peter Xu Changes since v3 [8]: - changed retry path in folio_lock_anon_vma_read() to unlock and then relock RCU, per Peter Xu - removed cross-mm support from initial patchset, per David Hildenbrand - replaced BUG_ONs with VM_WARN_ON or WARN_ON_ONCE, per David Hildenbrand - added missing cache flushing, per Lokesh Gidra and Peter Xu - updated manpage text in the patch description, per Peter Xu - renamed internal functions from "remap" to "move", per Peter Xu - added mmap_changing check after taking mmap_lock, per Peter Xu - changed uffd context check to ensure dst_mm is registered onto uffd we are operating on, Peter Xu and David Hildenbrand - changed to non-maybe variants of maybe*_mkwrite(), per David Hildenbrand - fixed warning for CONFIG_TRANSPARENT_HUGEPAGE=n, per kernel test robot - comments cleanup, per David Hildenbrand and Peter Xu - checks for VM_IO,VM_PFNMAP,VM_HUGETLB,..., per David Hildenbrand - prevent moving pinned pages, per Peter Xu - changed uffd tests to call move uffd_test_ctx_clear() at the end of the test run instead of in the beginning of the next run - added support for testcase-specific ops - added test for moving PMD-aligned blocks Changes since v2 [5]: - renamed UFFDIO_REMAP to UFFDIO_MOVE, per David Hildenbrand - rebase over mm-unstable to use folio_move_anon_rmap(), per David Hildenbrand - added text for manpage explaining DONTFORK and KSM requirements for this feature, per David Hildenbrand - check for anon_vma changes in the fast path of folio_lock_anon_vma_read, per Peter Xu - updated the title and description of the first patch, per David Hildenbrand - updating comments in folio_lock_anon_vma_read() explaining the need for anon_vma checks, per David Hildenbrand - changed all mapcount checks to PageAnonExclusive, per Jann Horn and David Hildenbrand - changed counters in remap_swap_pte() from MM_ANONPAGES to MM_SWAPENTS, per Jann Horn - added a check for PTE change after folio is locked in remap_pages_pte(), per Jann Horn - added handling of PMD migration entries and bailout when pmd_devmap(), per Jann Horn - added checks to ensure both src and dst VMAs are writable, per Peter Xu - added UFFD_FEATURE_MOVE, per Peter Xu - removed obsolete comments, per Peter Xu - renamed remap_anon_pte to remap_present_pte, per Peter Xu - added a comment for folio_get_anon_vma() explaining the need for anon_vma checks, per Peter Xu - changed error handling in remap_pages() to make it more clear, per Peter Xu - changed EFAULT to EAGAIN to retry when a hugepage appears or disappears from under us, per Peter Xu - added links to previous upstreaming attempts, per David Hildenbrand Changes since v1 [4]: - add mmget_not_zero in userfaultfd_remap, per Jann Horn - removed extern from function definitions, per Matthew Wilcox - converted to folios in remap_pages_huge_pmd, per Matthew Wilcox - use PageAnonExclusive in remap_pages_huge_pmd, per David Hildenbrand - handle pgtable transfers between MMs, per Jann Horn - ignore concurrent A/D pte bit changes, per Jann Horn - split functions into smaller units, per David Hildenbrand - test for folio_test_large in remap_anon_pte, per Matthew Wilcox - use pte_swp_exclusive for swapcount check, per David Hildenbrand - eliminated use of mmu_notifier_invalidate_range_start_nonblock, per Jann Horn - simplified THP alignment checks, per Jann Horn - refactored the loop inside remap_pages, per Jann Horn - additional clarifying comments, per Jann Horn Main changes since Andrea's last version [1]: - Trivial translations from page to folio, mmap_sem to mmap_lock - Replace pmd_trans_unstable() with pte_offset_map_nolock() and handle its possible failure - Move pte mapping into remap_pages_pte to allow for retries when source page or anon_vma is contended. Since pte_offset_map_nolock() start RCU read section, we can't block anymore after mapping a pte, so have to unmap the ptesm do the locking and retry. - Add and use anon_vma_trylock_write() to avoid blocking while in RCU read section. - Accommodate changes in mmu_notifier_range_init() API, switch to mmu_notifier_invalidate_range_start_nonblock() to avoid blocking while in RCU read section. - Open-code now removed __swp_swapcount() - Replace pmd_read_atomic() with pmdp_get_lockless() - Add new selftest for UFFDIO_MOVE [1] https://gitlab.com/aarcange/aa/-/commit/2aec7aea56b10438a3881a20a411aa4b1fc… [2] https://lore.kernel.org/all/1425575884-2574-1-git-send-email-aarcange@redha… [3] https://lore.kernel.org/linux-mm/CA+EESO4uO84SSnBhArH4HvLNhaUQ5nZKNKXqxRCyj… [4] https://lore.kernel.org/all/20230914152620.2743033-1-surenb@google.com/ [5] https://lore.kernel.org/all/20230923013148.1390521-1-surenb@google.com/ [6] https://lore.kernel.org/all/1425575884-2574-21-git-send-email-aarcange@redh… [7] https://lore.kernel.org/all/cover.1547251023.git.blake.caldwell@colorado.ed… [8] https://lore.kernel.org/all/20231009064230.2952396-1-surenb@google.com/ [9] https://lore.kernel.org/all/20231028003819.652322-1-surenb@google.com/ [10] https://lore.kernel.org/all/20231121171643.3719880-1-surenb@google.com/ Andrea Arcangeli (2): mm/rmap: support move to different root anon_vma in folio_move_anon_rmap() userfaultfd: UFFDIO_MOVE uABI Suren Baghdasaryan (3): selftests/mm: call uffd_test_ctx_clear at the end of the test selftests/mm: add uffd_test_case_ops to allow test case-specific operations selftests/mm: add UFFDIO_MOVE ioctl test Documentation/admin-guide/mm/userfaultfd.rst | 3 + fs/userfaultfd.c | 72 +++ include/linux/rmap.h | 5 + include/linux/userfaultfd_k.h | 11 + include/uapi/linux/userfaultfd.h | 29 +- mm/huge_memory.c | 122 ++++ mm/khugepaged.c | 3 + mm/rmap.c | 30 + mm/userfaultfd.c | 614 +++++++++++++++++++ tools/testing/selftests/mm/uffd-common.c | 39 +- tools/testing/selftests/mm/uffd-common.h | 9 + tools/testing/selftests/mm/uffd-stress.c | 5 +- tools/testing/selftests/mm/uffd-unit-tests.c | 192 ++++++ 13 files changed, 1130 insertions(+), 4 deletions(-) -- 2.43.0.rc2.451.g8631bc7472-goog

4 months

7
43
0 0

[PATCH bpf-next v2 0/6] selftests/bpf: Various sockmap-related fixes

by Michal Luczaj

Series takes care of few bugs and missing features with the aim to improve the test coverage of sockmap/sockhash. Last patch is a create_pair() rewrite making use of __attribute__((cleanup)) to handle socket fd lifetime. Signed-off-by: Michal Luczaj <mhal(a)rbox.co> --- Changes in v2: - Rebase on bpf-next (Jakub) - Use cleanup helpers from kernel's cleanup.h (Jakub) - Fix subject of patch 3, rephrase patch 4, use correct prefix - Link to v1: https://lore.kernel.org/r/20240724-sockmap-selftest-fixes-v1-0-46165d224712… Changes in v1: - No declarations in function body (Jakub) - Don't touch output arguments until function succeeds (Jakub) - Link to v0: https://lore.kernel.org/netdev/027fdb41-ee11-4be0-a493-22f28a1abd7c@rbox.co/ --- Michal Luczaj (6): selftests/bpf: Support more socket types in create_pair() selftests/bpf: Socket pair creation, cleanups selftests/bpf: Simplify inet_socketpair() and vsock_socketpair_connectible() selftests/bpf: Honour the sotype of af_unix redir tests selftests/bpf: Exercise SOCK_STREAM unix_inet_redir_to_connected() selftests/bpf: Introduce __attribute__((cleanup)) in create_pair() .../selftests/bpf/prog_tests/sockmap_basic.c | 28 ++-- .../selftests/bpf/prog_tests/sockmap_helpers.h | 149 ++++++++++++++------- .../selftests/bpf/prog_tests/sockmap_listen.c | 117 ++-------------- 3 files changed, 124 insertions(+), 170 deletions(-) --- base-commit: 92cc2456e9775dc4333fb4aa430763ae4ac2f2d9 change-id: 20240729-selftest-sockmap-fixes-bcca996e143b Best regards, -- Michal Luczaj <mhal(a)rbox.co>

4 months, 2 weeks

3
26
0 0

[PATCH bpf-next v2] arm64, bpf: Add 12-argument support for bpf trampoline

by Puranjay Mohan

The arm64 bpf JIT currently supports attaching the trampoline to functions with <= 8 arguments. This is because up to 8 arguments can be passed in registers r0-r7. If there are more than 8 arguments then the 9th and later arguments are passed on the stack, with SP pointing to the first stacked argument. See aapcs64[1] for more details. If the 8th argument is a structure of size > 8B, then it is passed fully on stack and r7 is not used for passing any argument. If there is a 9th argument, it will be passed on the stack, even though r7 is available. Add the support of storing and restoring arguments passed on the stack to the arm64 bpf trampoline. This will allow attaching the trampoline to functions that take up to 12 arguments. [1] https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#parame… Signed-off-by: Puranjay Mohan <puranjay(a)kernel.org> --- Changes in V1 -> V2: V1: https://lore.kernel.org/all/20240704173227.130491-1-puranjay@kernel.org/ - Fixed the argument handling for composite types (structs) --- arch/arm64/net/bpf_jit_comp.c | 139 ++++++++++++++----- tools/testing/selftests/bpf/DENYLIST.aarch64 | 3 - 2 files changed, 107 insertions(+), 35 deletions(-) diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 751331f5ba90..063bf5e11fc6 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -30,6 +30,8 @@ #define TMP_REG_3 (MAX_BPF_JIT_REG + 3) #define FP_BOTTOM (MAX_BPF_JIT_REG + 4) #define ARENA_VM_START (MAX_BPF_JIT_REG + 5) +/* Up to eight function arguments are passed in registers r0-r7 */ +#define ARM64_MAX_REG_ARGS 8 #define check_imm(bits, imm) do { \ if ((((imm) > 0) && ((imm) >> (bits))) || \ @@ -2001,26 +2003,51 @@ static void invoke_bpf_mod_ret(struct jit_ctx *ctx, struct bpf_tramp_links *tl, } } -static void save_args(struct jit_ctx *ctx, int args_off, int nregs) +static void save_args(struct jit_ctx *ctx, int args_off, int orig_sp_off, + int nargs, int nreg_args) { + const u8 tmp = bpf2a64[TMP_REG_1]; + int arg_pos; int i; - for (i = 0; i < nregs; i++) { - emit(A64_STR64I(i, A64_SP, args_off), ctx); + for (i = 0; i < nargs; i++) { + if (i < nreg_args) { + emit(A64_STR64I(i, A64_SP, args_off), ctx); + } else { + arg_pos = orig_sp_off + (i - nreg_args) * 8; + emit(A64_LDR64I(tmp, A64_SP, arg_pos), ctx); + emit(A64_STR64I(tmp, A64_SP, args_off), ctx); + } args_off += 8; } } -static void restore_args(struct jit_ctx *ctx, int args_off, int nregs) +static void restore_args(struct jit_ctx *ctx, int args_off, int nreg_args) { int i; - for (i = 0; i < nregs; i++) { + for (i = 0; i < nreg_args; i++) { emit(A64_LDR64I(i, A64_SP, args_off), ctx); args_off += 8; } } +static void restore_stack_args(struct jit_ctx *ctx, int args_off, int stk_arg_off, + int nargs, int nreg_args) +{ + const u8 tmp = bpf2a64[TMP_REG_1]; + int arg_pos; + int i; + + for (i = nreg_args; i < nargs; i++) { + arg_pos = args_off + i * 8; + emit(A64_LDR64I(tmp, A64_SP, arg_pos), ctx); + emit(A64_STR64I(tmp, A64_SP, stk_arg_off), ctx); + + stk_arg_off += 8; + } +} + /* Based on the x86's implementation of arch_prepare_bpf_trampoline(). * * bpf prog and function entry before bpf trampoline hooked: @@ -2034,15 +2061,17 @@ static void restore_args(struct jit_ctx *ctx, int args_off, int nregs) */ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, struct bpf_tramp_links *tlinks, void *func_addr, - int nregs, u32 flags) + int nargs, int nreg_args, u32 flags) { int i; int stack_size; + int stk_arg_off; + int orig_sp_off; int retaddr_off; int regs_off; int retval_off; int args_off; - int nregs_off; + int nargs_off; int ip_off; int run_ctx_off; struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY]; @@ -2052,6 +2081,7 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, __le32 **branches = NULL; /* trampoline stack layout: + * SP + orig_sp_off [ first stack arg ] if nargs > 8 * [ parent ip ] * [ FP ] * SP + retaddr_off [ self ip ] @@ -2069,14 +2099,24 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, * [ ... ] * SP + args_off [ arg reg 1 ] * - * SP + nregs_off [ arg regs count ] + * SP + nargs_off [ arg count ] * * SP + ip_off [ traced function ] BPF_TRAMP_F_IP_ARG flag * * SP + run_ctx_off [ bpf_tramp_run_ctx ] + * + * [ stack_argN ] + * [ ... ] + * SP + stk_arg_off [ stack_arg1 ] BPF_TRAMP_F_CALL_ORIG */ stack_size = 0; + stk_arg_off = stack_size; + if ((flags & BPF_TRAMP_F_CALL_ORIG) && (nargs - nreg_args > 0)) { + /* room for saving arguments passed on stack */ + stack_size += (nargs - nreg_args) * 8; + } + run_ctx_off = stack_size; /* room for bpf_tramp_run_ctx */ stack_size += round_up(sizeof(struct bpf_tramp_run_ctx), 8); @@ -2086,13 +2126,13 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, if (flags & BPF_TRAMP_F_IP_ARG) stack_size += 8; - nregs_off = stack_size; + nargs_off = stack_size; /* room for args count */ stack_size += 8; args_off = stack_size; /* room for args */ - stack_size += nregs * 8; + stack_size += nargs * 8; /* room for return value */ retval_off = stack_size; @@ -2110,6 +2150,11 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, /* return address locates above FP */ retaddr_off = stack_size + 8; + /* original SP position + * stack_size + parent function frame + patched function frame + */ + orig_sp_off = stack_size + 32; + /* bpf trampoline may be invoked by 3 instruction types: * 1. bl, attached to bpf prog or kernel function via short jump * 2. br, attached to bpf prog or kernel function via long jump @@ -2135,12 +2180,12 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, emit(A64_STR64I(A64_R(10), A64_SP, ip_off), ctx); } - /* save arg regs count*/ - emit(A64_MOVZ(1, A64_R(10), nregs, 0), ctx); - emit(A64_STR64I(A64_R(10), A64_SP, nregs_off), ctx); + /* save argument count */ + emit(A64_MOVZ(1, A64_R(10), nargs, 0), ctx); + emit(A64_STR64I(A64_R(10), A64_SP, nargs_off), ctx); - /* save arg regs */ - save_args(ctx, args_off, nregs); + /* save arguments passed in regs and on the stack */ + save_args(ctx, args_off, orig_sp_off, nargs, nreg_args); /* save callee saved registers */ emit(A64_STR64I(A64_R(19), A64_SP, regs_off), ctx); @@ -2167,7 +2212,10 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, } if (flags & BPF_TRAMP_F_CALL_ORIG) { - restore_args(ctx, args_off, nregs); + /* restore arguments that were passed in registers */ + restore_args(ctx, args_off, nreg_args); + /* restore arguments that were passed on the stack */ + restore_stack_args(ctx, args_off, stk_arg_off, nargs, nreg_args); /* call original func */ emit(A64_LDR64I(A64_R(10), A64_SP, retaddr_off), ctx); emit(A64_ADR(A64_LR, AARCH64_INSN_SIZE * 2), ctx); @@ -2196,7 +2244,7 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, } if (flags & BPF_TRAMP_F_RESTORE_REGS) - restore_args(ctx, args_off, nregs); + restore_args(ctx, args_off, nreg_args); /* restore callee saved register x19 and x20 */ emit(A64_LDR64I(A64_R(19), A64_SP, regs_off), ctx); @@ -2228,19 +2276,42 @@ static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im, return ctx->idx; } -static int btf_func_model_nregs(const struct btf_func_model *m) +static int btf_func_model_nargs(const struct btf_func_model *m) { - int nregs = m->nr_args; + int nargs = m->nr_args; int i; - /* extra registers needed for struct argument */ + /* extra registers or stack slots needed for struct argument */ for (i = 0; i < MAX_BPF_FUNC_ARGS; i++) { /* The arg_size is at most 16 bytes, enforced by the verifier. */ if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG) - nregs += (m->arg_size[i] + 7) / 8 - 1; + nargs += (m->arg_size[i] + 7) / 8 - 1; } - return nregs; + return nargs; +} + +/* get the count of the regs that are used to pass arguments */ +static int btf_func_model_nreg_args(const struct btf_func_model *m) +{ + int nargs = m->nr_args; + int nreg_args = 0; + int i; + + for (i = 0; i < nargs; i++) { + /* The arg_size is at most 16 bytes, enforced by the verifier. */ + if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG) { + /* struct members are all in the registers or all + * on the stack. + */ + if (nreg_args + ((m->arg_size[i] + 7) / 8 - 1) > 7) + break; + nreg_args += (m->arg_size[i] + 7) / 8 - 1; + } + nreg_args++; + } + + return (nreg_args > ARM64_MAX_REG_ARGS ? ARM64_MAX_REG_ARGS : nreg_args); } int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, @@ -2251,14 +2322,16 @@ int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, .idx = 0, }; struct bpf_tramp_image im; - int nregs, ret; + int nargs, nreg_args, ret; - nregs = btf_func_model_nregs(m); - /* the first 8 registers are used for arguments */ - if (nregs > 8) + nargs = btf_func_model_nargs(m); + if (nargs > MAX_BPF_FUNC_ARGS) return -ENOTSUPP; - ret = prepare_trampoline(&ctx, &im, tlinks, func_addr, nregs, flags); + nreg_args = btf_func_model_nreg_args(m); + + ret = prepare_trampoline(&ctx, &im, tlinks, func_addr, nargs, nreg_args, + flags); if (ret < 0) return ret; @@ -2285,7 +2358,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *ro_image, u32 flags, struct bpf_tramp_links *tlinks, void *func_addr) { - int ret, nregs; + int ret, nargs, nreg_args; void *image, *tmp; u32 size = ro_image_end - ro_image; @@ -2302,13 +2375,15 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *ro_image, .idx = 0, }; - nregs = btf_func_model_nregs(m); - /* the first 8 registers are used for arguments */ - if (nregs > 8) + nargs = btf_func_model_nargs(m); + if (nargs > MAX_BPF_FUNC_ARGS) return -ENOTSUPP; + nreg_args = btf_func_model_nreg_args(m); + jit_fill_hole(image, (unsigned int)(ro_image_end - ro_image)); - ret = prepare_trampoline(&ctx, im, tlinks, func_addr, nregs, flags); + ret = prepare_trampoline(&ctx, im, tlinks, func_addr, nargs, nreg_args, + flags); if (ret > 0 && validate_code(&ctx) < 0) { ret = -EINVAL; diff --git a/tools/testing/selftests/bpf/DENYLIST.aarch64 b/tools/testing/selftests/bpf/DENYLIST.aarch64 index 3c7c3e79aa93..e865451e90d2 100644 --- a/tools/testing/selftests/bpf/DENYLIST.aarch64 +++ b/tools/testing/selftests/bpf/DENYLIST.aarch64 @@ -4,9 +4,6 @@ fexit_sleep # The test never returns. The r kprobe_multi_bench_attach # needs CONFIG_FPROBE kprobe_multi_test # needs CONFIG_FPROBE module_attach # prog 'kprobe_multi': failed to auto-attach: -95 -fentry_test/fentry_many_args # fentry_many_args:FAIL:fentry_many_args_attach unexpected error: -524 -fexit_test/fexit_many_args # fexit_many_args:FAIL:fexit_many_args_attach unexpected error: -524 -tracing_struct/struct_many_args # struct_many_args:FAIL:tracing_struct_many_args__attach unexpected error: -524 fill_link_info/kprobe_multi_link_info # bpf_program__attach_kprobe_multi_opts unexpected error: -95 fill_link_info/kretprobe_multi_link_info # bpf_program__attach_kprobe_multi_opts unexpected error: -95 fill_link_info/kprobe_multi_invalid_ubuff # bpf_program__attach_kprobe_multi_opts unexpected error: -95 -- 2.40.1

6 months

3
4
0 0

[PATCH v2 0/6] cleanups, fixes, and progress towards avoiding "make headers"

by John Hubbard

Jeff Xu, I apologize for this churn: I was forced to drop your Reviewed-by and Tested-by tags from 2 of the 3 mseal patches, because the __NR_mseal fix is completely different now. Changes since v1: a) Reworked the mseal fix to use the kernel's in-tree unistd*.h files, instead of hacking in a __NR_mseal definition directly. (Thanks to David Hildenbrand for pointing out that this needed to be done.) b) Fixed the subject line of the kvm and mdwe patch. c) Reordered the patches so as to group the mseal changes together. d) ADDED an additional patch, 6/6, to remove various __NR_xx items and checks from the mm selftests. Cover letter, updated for v2: Eventually, once the build succeeds on a sufficiently old distro, the idea is to delete $(KHDR_INCLUDES) from the selftests/mm build, and then after that, from selftests/lib.mk and all of the other selftest builds. For now, this series merely achieves a clean build of selftests/mm on a not-so-old distro: Ubuntu 23.04. In other words, after this series is applied, it is possible to delete $(KHDR_INCLUDES) from selftests/mm/Makefile and the build will still succeed. 1. Add tools/uapi/asm/unistd_[32|x32|64].h files, which include definitions of __NR_mseal, and include them (indirectly) from the files that use __NR_mseal. The new files are copied from ./usr/include/asm, which is how we have agreed to do this sort of thing, see [1]. 2. Add fs.h, similarly created: it was copied directly from a snapshot of ./usr/include/linux/fs.h after running "make headers". 3. Add a few selected prctl.h values that the ksm and mdwe tests require. 4. Factor out some common code from mseal_test.c and seal_elf.c, into a new mseal_helpers.h file. 5. Remove local __NR_* definitions and checks. [1] commit e076eaca5906 ("selftests: break the dependency upon local header files") John Hubbard (6): selftests/mm: mseal, self_elf: fix missing __NR_mseal selftests/mm: mseal, self_elf: factor out test macros and other duplicated items selftests/mm: mseal, self_elf: rename TEST_END_CHECK to REPORT_TEST_PASS selftests/mm: fix vm_util.c build failures: add snapshot of fs.h selftests/mm: kvm, mdwe fixes to avoid requiring "make headers" selftests/mm: remove local __NR_* definitions tools/include/uapi/asm/unistd_32.h | 458 ++++++++++++++++++ tools/include/uapi/asm/unistd_64.h | 380 +++++++++++++++ tools/include/uapi/asm/unistd_x32.h | 369 ++++++++++++++ tools/include/uapi/linux/fs.h | 392 +++++++++++++++ tools/testing/selftests/mm/hugepage-mremap.c | 2 +- .../selftests/mm/ksm_functional_tests.c | 8 +- tools/testing/selftests/mm/mdwe_test.c | 1 + tools/testing/selftests/mm/memfd_secret.c | 14 +- tools/testing/selftests/mm/mkdirty.c | 8 +- tools/testing/selftests/mm/mlock2.h | 1 + tools/testing/selftests/mm/mrelease_test.c | 2 +- tools/testing/selftests/mm/mseal_helpers.h | 41 ++ tools/testing/selftests/mm/mseal_test.c | 143 ++---- tools/testing/selftests/mm/pagemap_ioctl.c | 2 +- tools/testing/selftests/mm/protection_keys.c | 2 +- tools/testing/selftests/mm/seal_elf.c | 37 +- tools/testing/selftests/mm/uffd-common.c | 4 - tools/testing/selftests/mm/uffd-stress.c | 16 +- tools/testing/selftests/mm/uffd-unit-tests.c | 14 +- tools/testing/selftests/mm/vm_util.h | 15 + 20 files changed, 1717 insertions(+), 192 deletions(-) create mode 100644 tools/include/uapi/asm/unistd_32.h create mode 100644 tools/include/uapi/asm/unistd_64.h create mode 100644 tools/include/uapi/asm/unistd_x32.h create mode 100644 tools/include/uapi/linux/fs.h create mode 100644 tools/testing/selftests/mm/mseal_helpers.h base-commit: 2ccbdf43d5e758f8493a95252073cf9078a5fea5 -- 2.45.2

6 months, 1 week

4
22
0 0

selftests: core: unshare_test: WARNING: at mm/util.c:671 __kvmalloc_node_noprof

by Naresh Kamboju

The following kernel warning is noticed on all arch and all devices while running selftests: core: unshare_test on Linux next-20240823 and next-20240826. First seen on next-20240823. Good: next-20240822 BAD: next-20240823 and next-20240826 Reported-by: Linux Kernel Functional Testing <lkft(a)linaro.org> Crash log: -------- # selftests: core: unshare_test <4>[ 61.084149] ------------[ cut here ]------------ <4>[ 61.085175] WARNING: CPU: 0 PID: 477 at mm/util.c:671 __kvmalloc_node_noprof (mm/util.c:671 (discriminator 1)) <4>[ 61.088958] Modules linked in: crct10dif_ce sm3_ce sm3 sha3_ce sha512_ce sha512_arm64 drm fuse backlight dm_mod ip_tables x_tables <4>[ 61.093141] CPU: 0 UID: 0 PID: 477 Comm: unshare_test Not tainted 6.11.0-rc5-next-20240826 #1 <4>[ 61.094558] Hardware name: linux,dummy-virt (DT) <4>[ 61.096763] pstate: 23400009 (nzCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) <4>[ 61.097841] pc : __kvmalloc_node_noprof (mm/util.c:671 (discriminator 1)) <4>[ 61.099701] lr : __kvmalloc_node_noprof (mm/util.c:661) <4>[ 61.100448] sp : ffff800080abbce0 <4>[ 61.100819] x29: ffff800080abbcf0 x28: fff0000004549280 x27: 0000000000000000 <4>[ 61.101744] x26: 0000000000000000 x25: 0000000000000000 x24: fff0000003615e40 <4>[ 61.102512] x23: fff0000003615ec0 x22: bfafa45863b285c8 x21: 0000000200002000 <4>[ 61.103232] x20: 00000000ffffffff x19: 0000000000400cc0 x18: 0000000000000000 <4>[ 61.104053] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 <4>[ 61.104927] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 <4>[ 61.105752] x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 <4>[ 61.106606] x8 : 0000000000000001 x7 : 0000000000000001 x6 : 0000000000000005 <4>[ 61.107377] x5 : 0000000000000000 x4 : fff0000004549280 x3 : 0000000000000000 <4>[ 61.108207] x2 : 0000000000000000 x1 : 000000007fffffff x0 : 0000000000000000 <4>[ 61.109262] Call trace: <4>[ 61.109619] __kvmalloc_node_noprof (mm/util.c:671 (discriminator 1)) <4>[ 61.110248] alloc_fdtable (fs/file.c:133) <4>[ 61.110751] expand_files (include/linux/atomic/atomic-arch-fallback.h:457 include/linux/atomic/atomic-instrumented.h:33 fs/file.c:177 fs/file.c:238) <4>[ 61.111171] ksys_dup3 (fs/file.c:1337) <4>[ 61.111596] __arm64_sys_dup3 (fs/file.c:1355) <4>[ 61.112006] invoke_syscall (arch/arm64/include/asm/current.h:19 arch/arm64/kernel/syscall.c:54) <4>[ 61.112480] el0_svc_common.constprop.0 (include/linux/thread_info.h:127 (discriminator 2) arch/arm64/kernel/syscall.c:140 (discriminator 2)) <4>[ 61.112955] do_el0_svc (arch/arm64/kernel/syscall.c:152) <4>[ 61.113384] el0_svc (arch/arm64/include/asm/irqflags.h:55 arch/arm64/include/asm/irqflags.h:76 arch/arm64/kernel/entry-common.c:165 arch/arm64/kernel/entry-common.c:178 arch/arm64/kernel/entry-common.c:713) <4>[ 61.113742] el0t_64_sync_handler (arch/arm64/kernel/entry-common.c:731) <4>[ 61.115181] el0t_64_sync (arch/arm64/kernel/entry.S:598) <4>[ 61.115709] ---[ end trace 0000000000000000 ]--- Crash Log links, -------- - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20240826/te… Crash failed comparison: ---------- - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20240826/te… metadata: ---- git describe: next-20240823 and next-20240826 git repo: https://gitlab.com/Linaro/lkft/mirrors/next/linux-next git sha: c79c85875f1af04040fe4492ed94ce37ad729c4d kernel config: https://storage.tuxsuite.com/public/linaro/lkft/builds/2l2pZRzhgRkPgXIKLJCI… artifact location: https://storage.tuxsuite.com/public/linaro/lkft/builds/2l2pZRzhgRkPgXIKLJCI… build url: https://storage.tuxsuite.com/public/linaro/lkft/builds/2l2pZRzhgRkPgXIKLJCI… toolchain: clang-18 and gcc-13 Steps to reproduce: --------- - https://tuxapi.tuxsuite.com/v1/groups/linaro/projects/lkft/tests/2l2paZVYTl… - https://tuxapi.tuxsuite.com/v1/groups/linaro/projects/lkft/tests/2l2paZVYTl… Please let me know if you need more information. -- Linaro LKFT https://lkft.linaro.org

7 months, 2 weeks

2
2
0 0

[PATCH 0/5] riscv: add support for Zaamo and Zalrsc extensions

by Clément Léger

Since commit e87412e621f1 ("integrate Zaamo and Zalrsc text (#1304)"), the A extension has been described as a set of instructions provided by Zaamo and Zalrsc. Add these two extensions. This series is based on the Zc one [1]. Link: https://lore.kernel.org/linux-riscv/20240619113529.676940-1-cleger@rivosinc… --- Clément Léger (5): dt-bindings: riscv: add Zaamo and Zalrsc ISA extension description riscv: add parsing for Zaamo and Zalrsc extensions riscv: hwprobe: export Zaamo and Zalrsc extensions RISC-V: KVM: Allow Zaamo/Zalrsc extensions for Guest/VM KVM: riscv: selftests: Add Zaamo/Zalrsc extensions to get-reg-list test Documentation/arch/riscv/hwprobe.rst | 8 ++++++++ .../devicetree/bindings/riscv/extensions.yaml | 19 +++++++++++++++++++ arch/riscv/include/asm/hwcap.h | 2 ++ arch/riscv/include/uapi/asm/hwprobe.h | 2 ++ arch/riscv/include/uapi/asm/kvm.h | 2 ++ arch/riscv/kernel/cpufeature.c | 9 ++++++++- arch/riscv/kernel/sys_hwprobe.c | 2 ++ arch/riscv/kvm/vcpu_onereg.c | 4 ++++ .../selftests/kvm/riscv/get-reg-list.c | 8 ++++++++ 9 files changed, 55 insertions(+), 1 deletion(-) -- 2.45.2

8 months, 1 week

4
11
0 0

[PATCH v4] memfd: `MFD_NOEXEC_SEAL` should not imply `MFD_ALLOW_SEALING`

by Barnabás Pőcze

`MFD_NOEXEC_SEAL` should remove the executable bits and set `F_SEAL_EXEC` to prevent further modifications to the executable bits as per the comment in the uapi header file: not executable and sealed to prevent changing to executable However, commit 105ff5339f498a ("mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC") that introduced this feature made it so that `MFD_NOEXEC_SEAL` unsets `F_SEAL_SEAL`, essentially acting as a superset of `MFD_ALLOW_SEALING`. Nothing implies that it should be so, and indeed up until the second version of the of the patchset[0] that introduced `MFD_EXEC` and `MFD_NOEXEC_SEAL`, `F_SEAL_SEAL` was not removed, however, it was changed in the third revision of the patchset[1] without a clear explanation. This behaviour is surprising for application developers, there is no documentation that would reveal that `MFD_NOEXEC_SEAL` has the additional effect of `MFD_ALLOW_SEALING`. Additionally, combined with `vm.memfd_noexec=2` it has the effect of making all memfds initially sealable. So do not remove `F_SEAL_SEAL` when `MFD_NOEXEC_SEAL` is requested, thereby returning to the pre-Linux 6.3 behaviour of only allowing sealing when `MFD_ALLOW_SEALING` is specified. Now, this is technically a uapi break. However, the damage is expected to be minimal. To trigger user visible change, a program has to do the following steps: - create memfd: - with `MFD_NOEXEC_SEAL`, - without `MFD_ALLOW_SEALING`; - try to add seals / check the seals. But that seems unlikely to happen intentionally since this change essentially reverts the kernel's behaviour to that of Linux <6.3, so if a program worked correctly on those older kernels, it will likely work correctly after this change. I have used Debian Code Search and GitHub to try to find potential breakages, and I could only find a single one. dbus-broker's memfd_create() wrapper is aware of this implicit `MFD_ALLOW_SEALING` behaviour, and tries to work around it[2]. This workaround will break. Luckily, this only affects the test suite, it does not affect the normal operations of dbus-broker. There is a PR with a fix[3]. I also carried out a smoke test by building a kernel with this change and booting an Arch Linux system into GNOME and Plasma sessions. There was also a previous attempt to address this peculiarity by introducing a new flag[4]. [0]: https://lore.kernel.org/lkml/20220805222126.142525-3-jeffxu@google.com/ [1]: https://lore.kernel.org/lkml/20221202013404.163143-3-jeffxu@google.com/ [2]: https://github.com/bus1/dbus-broker/blob/9eb0b7e5826fc76cad7b025bc46f267d4a… [3]: https://github.com/bus1/dbus-broker/pull/366 [4]: https://lore.kernel.org/lkml/20230714114753.170814-1-david@readahead.eu/ Cc: stable(a)vger.kernel.org Signed-off-by: Barnabás Pőcze <pobrn(a)protonmail.com> --- * v3: https://lore.kernel.org/linux-mm/20240611231409.3899809-1-jeffxu@chromium.o… * v2: https://lore.kernel.org/linux-mm/20240524033933.135049-1-jeffxu@google.com/ * v1: https://lore.kernel.org/linux-mm/20240513191544.94754-1-pobrn@protonmail.co… This fourth version returns to removing the inconsistency as opposed to documenting its existence, with the same code change as v1 but with a somewhat extended commit message. This is sent because I believe it is worth at least a try; it can be easily reverted if bigger application breakages are discovered than initially imagined. --- mm/memfd.c | 9 ++++----- tools/testing/selftests/memfd/memfd_test.c | 2 +- 2 files changed, 5 insertions(+), 6 deletions(-) diff --git a/mm/memfd.c b/mm/memfd.c index 7d8d3ab3fa37..8b7f6afee21d 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -356,12 +356,11 @@ SYSCALL_DEFINE2(memfd_create, inode->i_mode &= ~0111; file_seals = memfd_file_seals_ptr(file); - if (file_seals) { - *file_seals &= ~F_SEAL_SEAL; + if (file_seals) *file_seals |= F_SEAL_EXEC; - } - } else if (flags & MFD_ALLOW_SEALING) { - /* MFD_EXEC and MFD_ALLOW_SEALING are set */ + } + + if (flags & MFD_ALLOW_SEALING) { file_seals = memfd_file_seals_ptr(file); if (file_seals) *file_seals &= ~F_SEAL_SEAL; diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 95af2d78fd31..7b78329f65b6 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -1151,7 +1151,7 @@ static void test_noexec_seal(void) mfd_def_size, MFD_CLOEXEC | MFD_NOEXEC_SEAL); mfd_assert_mode(fd, 0666); - mfd_assert_has_seals(fd, F_SEAL_EXEC); + mfd_assert_has_seals(fd, F_SEAL_SEAL | F_SEAL_EXEC); mfd_fail_chmod(fd, 0777); close(fd); } -- 2.45.2

8 months, 3 weeks

4
5
0 0

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