From 461ab10ef7e6ea9b41a0571a7fc6a72af9549a3c Mon Sep 17 00:00:00 2001 From: Xiubo Li Date: Thu, 17 Nov 2022 10:43:21 +0800 Subject: ceph: switch to vfs_inode_has_locks() to fix file lock bug For the POSIX locks they are using the same owner, which is the thread id. And multiple POSIX locks could be merged into single one, so when checking whether the 'file' has locks may fail. For a file where some openers use locking and others don't is a really odd usage pattern though. Locks are like stoplights -- they only work if everyone pays attention to them. Just switch ceph_get_caps() to check whether any locks are set on the inode. If there are POSIX/OFD/FLOCK locks on the file at the time, we should set CHECK_FILELOCK, regardless of what fd was used to set the lock. Fixes: ff5d913dfc71 ("ceph: return -EIO if read/write against filp that lost file locks") Signed-off-by: Xiubo Li Reviewed-by: Jeff Layton Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov --- fs/ceph/caps.c | 2 +- fs/ceph/locks.c | 4 ---- fs/ceph/super.h | 1 - 3 files changed, 1 insertion(+), 6 deletions(-) (limited to 'fs') diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index 4b159f97fe7b..f75ad432f375 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -2913,7 +2913,7 @@ int ceph_get_caps(struct file *filp, int need, int want, loff_t endoff, int *got while (true) { flags &= CEPH_FILE_MODE_MASK; - if (atomic_read(&fi->num_locks)) + if (vfs_inode_has_locks(inode)) flags |= CHECK_FILELOCK; _got = 0; ret = try_get_cap_refs(inode, need, want, endoff, diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c index f3b461c708a8..6b3b8c299c17 100644 --- a/fs/ceph/locks.c +++ b/fs/ceph/locks.c @@ -32,18 +32,14 @@ void __init ceph_flock_init(void) static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src) { - struct ceph_file_info *fi = dst->fl_file->private_data; struct inode *inode = file_inode(dst->fl_file); atomic_inc(&ceph_inode(inode)->i_filelock_ref); - atomic_inc(&fi->num_locks); } static void ceph_fl_release_lock(struct file_lock *fl) { - struct ceph_file_info *fi = fl->fl_file->private_data; struct inode *inode = file_inode(fl->fl_file); struct ceph_inode_info *ci = ceph_inode(inode); - atomic_dec(&fi->num_locks); if (atomic_dec_and_test(&ci->i_filelock_ref)) { /* clear error when all locks are released */ spin_lock(&ci->i_ceph_lock); diff --git a/fs/ceph/super.h b/fs/ceph/super.h index 30bdb391a0dc..0ed3be75bb9a 100644 --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -790,7 +790,6 @@ struct ceph_file_info { struct list_head rw_contexts; u32 filp_gen; - atomic_t num_locks; }; struct ceph_dir_file_info { -- cgit v1.2.3 From 8e1858710d9a71d88acd922f2e95d1eddb90eea0 Mon Sep 17 00:00:00 2001 From: Xiubo Li Date: Thu, 17 Nov 2022 10:57:53 +0800 Subject: ceph: avoid use-after-free in ceph_fl_release_lock() When ceph releasing the file_lock it will try to get the inode pointer from the fl->fl_file, which the memory could already be released by another thread in filp_close(). Because in VFS layer the fl->fl_file doesn't increase the file's reference counter. Will switch to use ceph dedicate lock info to track the inode. And in ceph_fl_release_lock() we should skip all the operations if the fl->fl_u.ceph.inode is not set, which should come from the request file_lock. And we will set fl->fl_u.ceph.inode when inserting it to the inode lock list, which is when copying the lock. Link: https://tracker.ceph.com/issues/57986 Signed-off-by: Xiubo Li Reviewed-by: Jeff Layton Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov --- fs/ceph/locks.c | 20 ++++++++++++++++++-- include/linux/fs.h | 3 +++ 2 files changed, 21 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c index 6b3b8c299c17..9c8dc8a55e7e 100644 --- a/fs/ceph/locks.c +++ b/fs/ceph/locks.c @@ -34,18 +34,34 @@ static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src) { struct inode *inode = file_inode(dst->fl_file); atomic_inc(&ceph_inode(inode)->i_filelock_ref); + dst->fl_u.ceph.inode = igrab(inode); } +/* + * Do not use the 'fl->fl_file' in release function, which + * is possibly already released by another thread. + */ static void ceph_fl_release_lock(struct file_lock *fl) { - struct inode *inode = file_inode(fl->fl_file); - struct ceph_inode_info *ci = ceph_inode(inode); + struct inode *inode = fl->fl_u.ceph.inode; + struct ceph_inode_info *ci; + + /* + * If inode is NULL it should be a request file_lock, + * nothing we can do. + */ + if (!inode) + return; + + ci = ceph_inode(inode); if (atomic_dec_and_test(&ci->i_filelock_ref)) { /* clear error when all locks are released */ spin_lock(&ci->i_ceph_lock); ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK; spin_unlock(&ci->i_ceph_lock); } + fl->fl_u.ceph.inode = NULL; + iput(inode); } static const struct file_lock_operations ceph_fl_lock_ops = { diff --git a/include/linux/fs.h b/include/linux/fs.h index 066555ad1bf8..c1769a2c5d70 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1119,6 +1119,9 @@ struct file_lock { int state; /* state of grant or error if -ve */ unsigned int debug_id; } afs; + struct { + struct inode *inode; + } ceph; } fl_u; } __randomize_layout; -- cgit v1.2.3