From d2972f90d6f1c3948e94a99baa4eef080082eb8a Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Sat, 26 Dec 2020 18:07:01 +0800 Subject: [PATCH] BACKPORT: f2fs: enforce the immutable flag on open files commit e0fcd01510ad upstream. This patch ports commit 02b016ca7f99 ("ext4: enforce the immutable flag on open files") to f2fs. According to the chattr man page, "a file with the 'i' attribute cannot be modified..." Historically, this was only enforced when the file was opened, per the rest of the description, "... and the file can not be opened in write mode". There is general agreement that we should standardize all file systems to prevent modifications even for files that were opened at the time the immutable flag is set. Eventually, a change to enforce this at the VFS layer should be landing in mainline. Bug: 237904436 Cc: stable@kernel.org Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Change-Id: I9c74498ed3174309ff14158c8c3ad6dee6e1c8ca --- fs/f2fs/file.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index de5c5781c12a..7ce9e4a1a263 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -58,6 +58,9 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) bool need_alloc = true; int err = 0; + if (unlikely(IS_IMMUTABLE(inode))) + return VM_FAULT_SIGBUS; + if (unlikely(f2fs_cp_error(sbi))) { err = -EIO; goto err; @@ -874,6 +877,14 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr) if (unlikely(f2fs_cp_error(F2FS_I_SB(inode)))) return -EIO; + if (unlikely(IS_IMMUTABLE(inode))) + return -EPERM; + + if (unlikely(IS_APPEND(inode) && + (attr->ia_valid & (ATTR_MODE | ATTR_UID | + ATTR_GID | ATTR_TIMES_SET)))) + return -EPERM; + if ((attr->ia_valid & ATTR_SIZE) && !f2fs_is_compress_backend_ready(inode)) return -EOPNOTSUPP; @@ -3888,6 +3899,11 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from) inode_lock(inode); } + if (unlikely(IS_IMMUTABLE(inode))) { + ret = -EPERM; + goto unlock; + } + ret = generic_write_checks(iocb, from); if (ret > 0) { bool preallocated = false; @@ -3952,6 +3968,7 @@ write: if (ret > 0) f2fs_update_iostat(F2FS_I_SB(inode), APP_WRITE_IO, ret); } +unlock: inode_unlock(inode); out: trace_f2fs_file_write_iter(inode, iocb->ki_pos,