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Upper layers such as NFSD need a way to query whether a filesystem handles filenames in a case-sensitive manner. Report CIFS/SMB case handling behavior via FS_XFLAG_CASEFOLD and FS_XFLAG_CASENONPRESERVING. The authoritative source is the server itself: at mount time CIFS issues QueryFSInfo(FS_ATTRIBUTE_INFORMATION) and caches the reply on the tcon. That reply carries FILE_CASE_SENSITIVE_SEARCH and FILE_CASE_PRESERVED_NAMES, which reflect whatever case handling the share actually implements after SMB3.1.1 POSIX extensions negotiation. Translating those two bits into the VFS flags lets cifs_fileattr_get report what the server advertises rather than what the client was asked to pretend. QueryFSInfo is best-effort; the mount completes even if the server does not answer. MaxPathNameComponentLength is zero in that case and is used as the "no reply received" sentinel. When no reply is available, fall back to the nocase mount option so that the reported behavior agrees with the dentry comparison operations installed on the superblock. The callback is registered on cifs_dir_inode_ops so that NFSD, ksmbd, and other consumers querying case handling against a directory get a definitive answer, and on cifs_file_inode_ops to preserve FS_COMPR_FL reporting on regular files. cifs_set_ops() also installs cifs_namespace_inode_operations on DFS referral directories that carry IS_AUTOMOUNT; register the same callback there so the answer does not depend on whether the directory is a referral point. Registering fileattr_get routes FS_IOC_GETFLAGS through vfs_fileattr_get() and short-circuits the syscall's fallback to cifs_ioctl(). That fallback invoked CIFSGetExtAttr() under CONFIG_CIFS_POSIX and CONFIG_CIFS_ALLOW_INSECURE_LEGACY on servers advertising CIFS_UNIX_EXTATTR_CAP, surfacing the SMB1 Unix-extension immutable, append, and nodump bits. cifs_fileattr_get carries over only FS_COMPR_FL from cached cifsAttrs; the SMB1 extattr fetch is not reproduced. SMB1 is deprecated, and acquiring a netfid from within a dentry-only callback is not worth preserving a path tied to an insecure legacy dialect. Acked-by: Steve French <stfrench@microsoft.com> Reviewed-by: Roland Mainz <roland.mainz@nrubsig.org> Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Link: https://patch.msgid.link/20260507-case-sensitivity-v14-9-e62cc8200435@oracle.com Signed-off-by: Christian Brauner <brauner@kernel.org> |
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Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros * AI Coding Assistant - LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst