From c1dbb74c3ec73045ffb250da0a7e7f2a1d1234b6 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 30 Jul 2024 14:09:37 +0800 Subject: [PATCH 1/2] file: Factor files_lookup_fd_locked out of fcheck_files mainline inclusion from mainline-v5.11-rc1 commit 120ce2b0cd52abe73e8b16c23461eb14df5a87d8 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAGEF4 CVE: CVE-2024-41020 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=120ce2b0cd52abe73e8b16c23461eb14df5a87d8 -------------------------------- To make it easy to tell where files->file_lock protection is being used when looking up a file create files_lookup_fd_locked. Only allow this function to be called with the file_lock held. Update the callers of fcheck and fcheck_files that are called with the files->file_lock held to call files_lookup_fd_locked instead. Hopefully this makes it easier to quickly understand what is going on. The need for better names became apparent in the last round of discussion of this set of changes[1]. [1] https://lkml.kernel.org/r/CAHk-=wj8BQbgJFLa+J0e=iT-1qpmCRTbPAJ8gd6MJQ=kbRPqyQ@mail.gmail.com Link: https://lkml.kernel.org/r/20201120231441.29911-8-ebiederm@xmission.com Signed-off-by: Eric W. Biederman Signed-off-by: Yifan Qiao --- fs/file.c | 2 +- fs/locks.c | 14 ++++++++------ fs/proc/fd.c | 2 +- include/linux/fdtable.h | 7 +++++++ 4 files changed, 17 insertions(+), 8 deletions(-) diff --git a/fs/file.c b/fs/file.c index af3968e29ecf..404e21006d7f 100644 --- a/fs/file.c +++ b/fs/file.c @@ -1269,7 +1269,7 @@ static int ksys_dup3(unsigned int oldfd, unsigned int newfd, int flags) spin_lock(&files->file_lock); err = expand_files(files, newfd); - file = fcheck(oldfd); + file = files_lookup_fd_locked(files, oldfd); if (unlikely(!file)) goto Ebadf; if (unlikely(err < 0)) { diff --git a/fs/locks.c b/fs/locks.c index 4e4b36c330f9..ecd61b419bce 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -2536,14 +2536,15 @@ int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd, */ if (!error && file_lock->fl_type != F_UNLCK && !(file_lock->fl_flags & FL_OFDLCK)) { + struct files_struct *files = current->files; /* * We need that spin_lock here - it prevents reordering between * update of i_flctx->flc_posix and check for it done in * close(). rcu_read_lock() wouldn't do. */ - spin_lock(¤t->files->file_lock); - f = fcheck(fd); - spin_unlock(¤t->files->file_lock); + spin_lock(&files->file_lock); + f = files_lookup_fd_locked(files, fd); + spin_unlock(&files->file_lock); if (f != filp) { file_lock->fl_type = F_UNLCK; error = do_lock_file_wait(filp, cmd, file_lock); @@ -2667,14 +2668,15 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, */ if (!error && file_lock->fl_type != F_UNLCK && !(file_lock->fl_flags & FL_OFDLCK)) { + struct files_struct *files = current->files; /* * We need that spin_lock here - it prevents reordering between * update of i_flctx->flc_posix and check for it done in * close(). rcu_read_lock() wouldn't do. */ - spin_lock(¤t->files->file_lock); - f = fcheck(fd); - spin_unlock(¤t->files->file_lock); + spin_lock(&files->file_lock); + f = files_lookup_fd_locked(files, fd); + spin_unlock(&files->file_lock); if (f != filp) { file_lock->fl_type = F_UNLCK; error = do_lock_file_wait(filp, cmd, file_lock); diff --git a/fs/proc/fd.c b/fs/proc/fd.c index 81882a13212d..6640ec2e5c48 100644 --- a/fs/proc/fd.c +++ b/fs/proc/fd.c @@ -35,7 +35,7 @@ static int seq_show(struct seq_file *m, void *v) unsigned int fd = proc_fd(m->private); spin_lock(&files->file_lock); - file = fcheck_files(files, fd); + file = files_lookup_fd_locked(files, fd); if (file) { struct fdtable *fdt = files_fdtable(files); diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index e2df70d7bcc3..d3873fe55885 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -92,6 +92,13 @@ static inline struct file *__fcheck_files(struct files_struct *files, unsigned i return NULL; } +static inline struct file *files_lookup_fd_locked(struct files_struct *files, unsigned int fd) +{ + RCU_LOCKDEP_WARN(!lockdep_is_held(&files->file_lock), + "suspicious rcu_dereference_check() usage"); + return files_lookup_fd_raw(files, fd); +} + static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd) { RCU_LOCKDEP_WARN(!rcu_read_lock_held() && -- Gitee From 542ab9087cc4a88bb497f5c16146b4dde43168ff Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Tue, 30 Jul 2024 14:09:38 +0800 Subject: [PATCH 2/2] filelock: Fix fcntl/close race recovery compat path stable inclusion from stable-v5.10.223 commit 911cc83e56a2de5a40758766c6a70d6998248860 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAGEF4 CVE: CVE-2024-41020 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=911cc83e56a2de5a40758766c6a70d6998248860 -------------------------------- commit f8138f2ad2f745b9a1c696a05b749eabe44337ea upstream. When I wrote commit 3cad1bc01041 ("filelock: Remove locks reliably when fcntl/close race is detected"), I missed that there are two copies of the code I was patching: The normal version, and the version for 64-bit offsets on 32-bit kernels. Thanks to Greg KH for stumbling over this while doing the stable backport... Apply exactly the same fix to the compat path for 32-bit kernels. Fixes: c293621bbf67 ("[PATCH] stale POSIX lock handling") Cc: stable@kernel.org Link: https://bugs.chromium.org/p/project-zero/issues/detail?id=2563 Signed-off-by: Jann Horn Link: https://lore.kernel.org/r/20240723-fs-lock-recover-compatfix-v1-1-148096719529@google.com Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yifan Qiao --- fs/locks.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/locks.c b/fs/locks.c index ecd61b419bce..e68af0e28e8a 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -2662,8 +2662,9 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, error = do_lock_file_wait(filp, cmd, file_lock); /* - * Attempt to detect a close/fcntl race and recover by releasing the - * lock that was just acquired. There is no need to do that when we're + * Detect close/fcntl races and recover by zapping all POSIX locks + * associated with this file and our files_struct, just like on + * filp_flush(). There is no need to do that when we're * unlocking though, or for OFD locks. */ if (!error && file_lock->fl_type != F_UNLCK && @@ -2678,9 +2679,7 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, f = files_lookup_fd_locked(files, fd); spin_unlock(&files->file_lock); if (f != filp) { - file_lock->fl_type = F_UNLCK; - error = do_lock_file_wait(filp, cmd, file_lock); - WARN_ON_ONCE(error); + locks_remove_posix(filp, files); error = -EBADF; } } -- Gitee