From 27838d648617726f1043a55a87858d8c9ca41538 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 31 Jul 2024 09:31:02 +0800 Subject: [PATCH 1/3] file: Rename __fcheck_files to files_lookup_fd_raw mainline inclusion from mainline-v5.11-rc1 commit bebf684bf330915e6c96313ad7db89a5480fc9c2 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=bebf684bf330915e6c96313ad7db89a5480fc9c2 -------------------------------- The function fcheck despite it's comment is poorly named as it has no callers that only check it's return value. All of fcheck's callers use the returned file descriptor. The same is true for fcheck_files and __fcheck_files. A new less confusing name is needed. In addition the names of these functions are confusing as they do not report the kind of locks that are needed to be held when these functions are called making error prone to use them. To remedy this I am making the base functio name lookup_fd and will and prefixes and sufficies to indicate the rest of the context. Name the function (previously called __fcheck_files) that proceeds from a struct files_struct, looks up the struct file of a file descriptor, and requires it's callers to verify all of the appropriate locks are held files_lookup_fd_raw. 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/20201120231441.29911-7-ebiederm@xmission.com Signed-off-by: Eric W. Biederman Signed-off-by: Yifan Qiao --- fs/file.c | 2 +- include/linux/fdtable.h | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/file.c b/fs/file.c index af3968e29ecf..640dced51a53 100644 --- a/fs/file.c +++ b/fs/file.c @@ -1034,7 +1034,7 @@ static unsigned long __fget_light(unsigned int fd, fmode_t mask) struct file *file; if (atomic_read(&files->count) == 1) { - file = __fcheck_files(files, fd); + file = files_lookup_fd_raw(files, fd); if (!file || unlikely(file->f_mode & mask)) return 0; return (unsigned long)file; diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index e2df70d7bcc3..4b4410fc1282 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -81,7 +81,7 @@ struct dentry; /* * The caller must ensure that fd table isn't shared or hold rcu or file lock */ -static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd) +static inline struct file *files_lookup_fd_raw(struct files_struct *files, unsigned int fd) { struct fdtable *fdt = rcu_dereference_raw(files->fdt); @@ -97,7 +97,7 @@ static inline struct file *fcheck_files(struct files_struct *files, unsigned int RCU_LOCKDEP_WARN(!rcu_read_lock_held() && !lockdep_is_held(&files->file_lock), "suspicious rcu_dereference_check() usage"); - return __fcheck_files(files, fd); + return files_lookup_fd_raw(files, fd); } /* -- Gitee From eff0d06c15bde4d50b0e261562e53e7af7586c4f Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 31 Jul 2024 09:31:03 +0800 Subject: [PATCH 2/3] 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 640dced51a53..d6c57c837541 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 4b4410fc1282..e9f2884bc673 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -92,6 +92,13 @@ static inline struct file *files_lookup_fd_raw(struct files_struct *files, unsig 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 91b9702dd1305b5ef8d77c48a836f9a80be1e3b8 Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Wed, 31 Jul 2024 09:31:04 +0800 Subject: [PATCH 3/3] 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