[PATCH kernel-4.19 2/7] fuse: fix bad inode

From: Miklos Szeredi mszeredi@redhat.com

mainline inclusion from mainline-v5.11-rc1 commit 5d069dbe8aaf2a197142558b6fb2978189ba3454 category: bugfix bugzilla: NA CVE: CVE-2020-36322

--------------------------------

Jan Kara's analysis of the syzbot report (edited):

The reproducer opens a directory on FUSE filesystem, it then attaches dnotify mark to the open directory. After that a fuse_do_getattr() call finds that attributes returned by the server are inconsistent, and calls make_bad_inode() which, among other things does:

inode->i_mode = S_IFREG;

This then confuses dnotify which doesn't tear down its structures properly and eventually crashes.

Avoid calling make_bad_inode() on a live inode: switch to a private flag on the fuse inode. Also add the test to ops which the bad_inode_ops would have caught.

This bug goes back to the initial merge of fuse in 2.6.14...

Reported-by: syzbot+f427adf9324b92652ccc@syzkaller.appspotmail.com Signed-off-by: Miklos Szeredi mszeredi@redhat.com Tested-by: Jan Kara jack@suse.cz Cc: stable@vger.kernel.org Conflicts: fs/fuse/inode.c fs/fuse/file.c fs/fuse/xattr.c fs/fuse/dir.c fs/fuse/fuse_i.h [yyl: replace is_bad_inode() with fuse_is_bad(), readdir.c is not added in kernel-4.19] Signed-off-by: Yang Yingliang yangyingliang@huawei.com Reviewed-by: zhangyi (F) yi.zhang@huawei.com Reviewed-by: Xiu Jianfeng xiujianfeng@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- fs/fuse/acl.c | 6 ++++++ fs/fuse/dir.c | 37 ++++++++++++++++++++++++++++++++----- fs/fuse/file.c | 21 ++++++++++++--------- fs/fuse/fuse_i.h | 12 ++++++++++++ fs/fuse/inode.c | 2 +- fs/fuse/xattr.c | 9 +++++++++ 6 files changed, 72 insertions(+), 15 deletions(-)

diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c index 5a48cee6d7d33..f529075a2ce87 100644 --- a/fs/fuse/acl.c +++ b/fs/fuse/acl.c @@ -19,6 +19,9 @@ struct posix_acl *fuse_get_acl(struct inode *inode, int type) void *value = NULL; struct posix_acl *acl;

+ if (fuse_is_bad(inode)) + return ERR_PTR(-EIO); + if (!fc->posix_acl || fc->no_getxattr) return NULL;

@@ -53,6 +56,9 @@ int fuse_set_acl(struct inode *inode, struct posix_acl *acl, int type) const char *name; int ret;

+ if (fuse_is_bad(inode)) + return -EIO; + if (!fc->posix_acl || fc->no_setxattr) return -EOPNOTSUPP;

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 6244345a5745b..29d8aa4844ff2 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -187,7 +187,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags) int ret;

inode = d_inode_rcu(entry); - if (inode && is_bad_inode(inode)) + if (inode && fuse_is_bad(inode)) goto invalid; else if (time_before64(fuse_dentry_time(entry), get_jiffies_64()) || (flags & LOOKUP_REVAL)) { @@ -364,6 +364,9 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, bool outarg_valid = true; bool locked;

+ if (fuse_is_bad(dir)) + return ERR_PTR(-EIO); + locked = fuse_lock_inode(dir); err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name, &outarg, &inode); @@ -504,6 +507,9 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry, struct fuse_conn *fc = get_fuse_conn(dir); struct dentry *res = NULL;

+ if (fuse_is_bad(dir)) + return -EIO; + if (d_in_lookup(entry)) { res = fuse_lookup(dir, entry, 0); if (IS_ERR(res)) @@ -552,6 +558,9 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args, int err; struct fuse_forget_link *forget;

+ if (fuse_is_bad(dir)) + return -EIO; + forget = fuse_alloc_forget(); if (!forget) return -ENOMEM; @@ -679,6 +688,9 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry) struct fuse_conn *fc = get_fuse_conn(dir); FUSE_ARGS(args);

+ if (fuse_is_bad(dir)) + return -EIO; + args.in.h.opcode = FUSE_UNLINK; args.in.h.nodeid = get_node_id(dir); args.in.numargs = 1; @@ -715,6 +727,9 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry) struct fuse_conn *fc = get_fuse_conn(dir); FUSE_ARGS(args);

+ if (fuse_is_bad(dir)) + return -EIO; + args.in.h.opcode = FUSE_RMDIR; args.in.h.nodeid = get_node_id(dir); args.in.numargs = 1; @@ -793,6 +808,9 @@ static int fuse_rename2(struct inode *olddir, struct dentry *oldent, struct fuse_conn *fc = get_fuse_conn(olddir); int err;

+ if (fuse_is_bad(olddir)) + return -EIO; + if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) return -EINVAL;

@@ -928,7 +946,7 @@ static int fuse_do_getattr(struct inode *inode, struct kstat *stat, if (!err) { if (fuse_invalid_attr(&outarg.attr) || (inode->i_mode ^ outarg.attr.mode) & S_IFMT) { - make_bad_inode(inode); + fuse_make_bad(inode); err = -EIO; } else { fuse_change_attributes(inode, &outarg.attr, @@ -1125,6 +1143,9 @@ static int fuse_permission(struct inode *inode, int mask) bool refreshed = false; int err = 0;

+ if (fuse_is_bad(inode)) + return -EIO; + if (!fuse_allow_current_process(fc)) return -EACCES;

@@ -1262,7 +1283,7 @@ static int fuse_direntplus_link(struct file *file, dput(dentry); goto retry; } - if (is_bad_inode(inode)) { + if (fuse_is_bad(inode)) { dput(dentry); return -EIO; } @@ -1360,7 +1381,7 @@ static int fuse_readdir(struct file *file, struct dir_context *ctx) u64 attr_version = 0; bool locked;

- if (is_bad_inode(inode)) + if (fuse_is_bad(inode)) return -EIO;

req = fuse_get_req(fc, 1); @@ -1718,7 +1739,7 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,

if (fuse_invalid_attr(&outarg.attr) || (inode->i_mode ^ outarg.attr.mode) & S_IFMT) { - make_bad_inode(inode); + fuse_make_bad(inode); err = -EIO; goto error; } @@ -1774,6 +1795,9 @@ static int fuse_setattr(struct dentry *entry, struct iattr *attr) struct file *file = (attr->ia_valid & ATTR_FILE) ? attr->ia_file : NULL; int ret;

+ if (fuse_is_bad(inode)) + return -EIO; + if (!fuse_allow_current_process(get_fuse_conn(inode))) return -EACCES;

@@ -1832,6 +1856,9 @@ static int fuse_getattr(const struct path *path, struct kstat *stat, struct inode *inode = d_inode(path->dentry); struct fuse_conn *fc = get_fuse_conn(inode);

+ if (fuse_is_bad(inode)) + return -EIO; + if (!fuse_allow_current_process(fc)) return -EACCES;

diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 6a3d89672ff71..c1af038920dc5 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -207,6 +207,9 @@ int fuse_open_common(struct inode *inode, struct file *file, bool isdir) fc->atomic_o_trunc && fc->writeback_cache;

+ if (fuse_is_bad(inode)) + return -EIO; + err = generic_file_open(inode, file); if (err) return err; @@ -408,7 +411,7 @@ static int fuse_flush(struct file *file, fl_owner_t id) struct fuse_flush_in inarg; int err;

- if (is_bad_inode(inode)) + if (fuse_is_bad(inode)) return -EIO;

if (fc->no_flush) @@ -456,7 +459,7 @@ int fuse_fsync_common(struct file *file, loff_t start, loff_t end, struct fuse_fsync_in inarg; int err;

- if (is_bad_inode(inode)) + if (fuse_is_bad(inode)) return -EIO;

inode_lock(inode); @@ -771,7 +774,7 @@ static int fuse_readpage(struct file *file, struct page *page) int err;

err = -EIO; - if (is_bad_inode(inode)) + if (fuse_is_bad(inode)) goto out;

err = fuse_do_readpage(file, page); @@ -898,7 +901,7 @@ static int fuse_readpages(struct file *file, struct address_space *mapping, int nr_alloc = min_t(unsigned, nr_pages, FUSE_MAX_PAGES_PER_REQ);

err = -EIO; - if (is_bad_inode(inode)) + if (fuse_is_bad(inode)) goto out;

data.file = file; @@ -1128,7 +1131,7 @@ static ssize_t fuse_perform_write(struct kiocb *iocb, int err = 0; ssize_t res = 0;

- if (is_bad_inode(inode)) + if (fuse_is_bad(inode)) return -EIO;

if (inode->i_size < pos + iov_iter_count(ii)) @@ -1421,7 +1424,7 @@ static ssize_t __fuse_direct_read(struct fuse_io_priv *io, ssize_t res; struct inode *inode = file_inode(io->iocb->ki_filp);

- if (is_bad_inode(inode)) + if (fuse_is_bad(inode)) return -EIO;

res = fuse_direct_io(io, iter, ppos, 0); @@ -1443,7 +1446,7 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from) struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb); ssize_t res;

- if (is_bad_inode(inode)) + if (fuse_is_bad(inode)) return -EIO;

/* Don't allow parallel writes to the same file */ @@ -1917,7 +1920,7 @@ static int fuse_writepages(struct address_space *mapping, int err;

err = -EIO; - if (is_bad_inode(inode)) + if (fuse_is_bad(inode)) goto out;

data.inode = inode; @@ -2702,7 +2705,7 @@ long fuse_ioctl_common(struct file *file, unsigned int cmd, if (!fuse_allow_current_process(fc)) return -EACCES;

- if (is_bad_inode(inode)) + if (fuse_is_bad(inode)) return -EIO;

return fuse_do_ioctl(file, cmd, arg, flags); diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index dbfc35efbefb6..3d88386047dfe 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -118,6 +118,8 @@ enum { FUSE_I_INIT_RDPLUS, /** An operation changing file size is in progress */ FUSE_I_SIZE_UNSTABLE, + /* Bad inode */ + FUSE_I_BAD, };

struct fuse_conn; @@ -700,6 +702,16 @@ static inline u64 get_node_id(struct inode *inode) return get_fuse_inode(inode)->nodeid; }

+static inline void fuse_make_bad(struct inode *inode) +{ + set_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state); +} + +static inline bool fuse_is_bad(struct inode *inode) +{ + return unlikely(test_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state)); +} + /** Device operations */ extern const struct file_operations fuse_dev_operations;

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index cb018315ecaf5..821597c618843 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -317,7 +317,7 @@ struct inode *fuse_iget(struct super_block *sb, u64 nodeid, unlock_new_inode(inode); } else if ((inode->i_mode ^ attr->mode) & S_IFMT) { /* Inode has changed type, any I/O on the old should fail */ - make_bad_inode(inode); + fuse_make_bad(inode); iput(inode); goto retry; } diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c index 433717640f78d..a4b65374bced4 100644 --- a/fs/fuse/xattr.c +++ b/fs/fuse/xattr.c @@ -113,6 +113,9 @@ ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size) struct fuse_getxattr_out outarg; ssize_t ret;

+ if (fuse_is_bad(inode)) + return -EIO; + if (!fuse_allow_current_process(fc)) return -EACCES;

@@ -178,6 +181,9 @@ static int fuse_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, void *value, size_t size) { + if (fuse_is_bad(inode)) + return -EIO; + return fuse_getxattr(inode, name, value, size); }

@@ -186,6 +192,9 @@ static int fuse_xattr_set(const struct xattr_handler *handler, const char *name, const void *value, size_t size, int flags) { + if (fuse_is_bad(inode)) + return -EIO; + if (!value) return fuse_removexattr(inode, name);