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Encoding file handles is usually performed by a filesystem >encode_fh()
method that may fail for various reasons.
The legacy users of exportfs_encode_fh(), namely, nfsd and
name_to_handle_at(2) syscall are ready to cope with the possibility
of failure to encode a file handle.
There are a few other users of exportfs_encode_{fh,fid}() that
currently have a WARN_ON() assertion when ->encode_fh() fails.
Relax those assertions because they are wrong.
The second linked bug report states commit 16aac5ad1f
("ovl: support
encoding non-decodable file handles") in v6.6 as the regressing commit,
but this is not accurate.
The aforementioned commit only increases the chances of the assertion
and allows triggering the assertion with the reproducer using overlayfs,
inotify and drop_caches.
Triggering this assertion was always possible with other filesystems and
other reasons of ->encode_fh() failures and more particularly, it was
also possible with the exact same reproducer using overlayfs that is
mounted with options index=on,nfs_export=on also on kernels < v6.6.
Therefore, I am not listing the aforementioned commit as a Fixes commit.
Backport hint: this patch will have a trivial conflict applying to
v6.6.y, and other trivial conflicts applying to stable kernels < v6.6.
Reported-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com
Tested-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-unionfs/671fd40c.050a0220.4735a.024f.GAE@google.com/
Reported-by: Dmitry Safonov <dima@arista.com>
Closes: https://lore.kernel.org/linux-fsdevel/CAGrbwDTLt6drB9eaUagnQVgdPBmhLfqqxAf3F+Juqy_o6oP8uw@mail.gmail.com/
Cc: stable@vger.kernel.org
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20241219115301.465396-1-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
142 lines
3.8 KiB
C
142 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/fsnotify_backend.h>
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#include <linux/idr.h>
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#include <linux/init.h>
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#include <linux/inotify.h>
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#include <linux/fanotify.h>
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#include <linux/kernel.h>
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#include <linux/namei.h>
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#include <linux/sched.h>
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#include <linux/types.h>
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#include <linux/seq_file.h>
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#include <linux/exportfs.h>
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#include "inotify/inotify.h"
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#include "fanotify/fanotify.h"
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#include "fdinfo.h"
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#include "fsnotify.h"
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#if defined(CONFIG_PROC_FS)
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#if defined(CONFIG_INOTIFY_USER) || defined(CONFIG_FANOTIFY)
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static void show_fdinfo(struct seq_file *m, struct file *f,
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void (*show)(struct seq_file *m,
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struct fsnotify_mark *mark))
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{
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struct fsnotify_group *group = f->private_data;
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struct fsnotify_mark *mark;
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fsnotify_group_lock(group);
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list_for_each_entry(mark, &group->marks_list, g_list) {
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show(m, mark);
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if (seq_has_overflowed(m))
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break;
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}
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fsnotify_group_unlock(group);
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}
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#if defined(CONFIG_EXPORTFS)
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static void show_mark_fhandle(struct seq_file *m, struct inode *inode)
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{
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DEFINE_FLEX(struct file_handle, f, f_handle, handle_bytes, MAX_HANDLE_SZ);
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int size, ret, i;
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size = f->handle_bytes >> 2;
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ret = exportfs_encode_fid(inode, (struct fid *)f->f_handle, &size);
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if ((ret == FILEID_INVALID) || (ret < 0))
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return;
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f->handle_type = ret;
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f->handle_bytes = size * sizeof(u32);
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seq_printf(m, "fhandle-bytes:%x fhandle-type:%x f_handle:",
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f->handle_bytes, f->handle_type);
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for (i = 0; i < f->handle_bytes; i++)
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seq_printf(m, "%02x", (int)f->f_handle[i]);
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}
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#else
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static void show_mark_fhandle(struct seq_file *m, struct inode *inode)
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{
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}
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#endif
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#ifdef CONFIG_INOTIFY_USER
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static void inotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark)
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{
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struct inotify_inode_mark *inode_mark;
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struct inode *inode;
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if (mark->connector->type != FSNOTIFY_OBJ_TYPE_INODE)
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return;
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inode_mark = container_of(mark, struct inotify_inode_mark, fsn_mark);
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inode = igrab(fsnotify_conn_inode(mark->connector));
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if (inode) {
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seq_printf(m, "inotify wd:%x ino:%lx sdev:%x mask:%x ignored_mask:0 ",
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inode_mark->wd, inode->i_ino, inode->i_sb->s_dev,
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inotify_mark_user_mask(mark));
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show_mark_fhandle(m, inode);
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seq_putc(m, '\n');
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iput(inode);
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}
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}
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void inotify_show_fdinfo(struct seq_file *m, struct file *f)
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{
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show_fdinfo(m, f, inotify_fdinfo);
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}
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#endif /* CONFIG_INOTIFY_USER */
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#ifdef CONFIG_FANOTIFY
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static void fanotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark)
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{
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unsigned int mflags = fanotify_mark_user_flags(mark);
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struct inode *inode;
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if (mark->connector->type == FSNOTIFY_OBJ_TYPE_INODE) {
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inode = igrab(fsnotify_conn_inode(mark->connector));
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if (!inode)
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return;
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seq_printf(m, "fanotify ino:%lx sdev:%x mflags:%x mask:%x ignored_mask:%x ",
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inode->i_ino, inode->i_sb->s_dev,
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mflags, mark->mask, mark->ignore_mask);
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show_mark_fhandle(m, inode);
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seq_putc(m, '\n');
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iput(inode);
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} else if (mark->connector->type == FSNOTIFY_OBJ_TYPE_VFSMOUNT) {
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struct mount *mnt = fsnotify_conn_mount(mark->connector);
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seq_printf(m, "fanotify mnt_id:%x mflags:%x mask:%x ignored_mask:%x\n",
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mnt->mnt_id, mflags, mark->mask, mark->ignore_mask);
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} else if (mark->connector->type == FSNOTIFY_OBJ_TYPE_SB) {
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struct super_block *sb = fsnotify_conn_sb(mark->connector);
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seq_printf(m, "fanotify sdev:%x mflags:%x mask:%x ignored_mask:%x\n",
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sb->s_dev, mflags, mark->mask, mark->ignore_mask);
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}
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}
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void fanotify_show_fdinfo(struct seq_file *m, struct file *f)
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{
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struct fsnotify_group *group = f->private_data;
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seq_printf(m, "fanotify flags:%x event-flags:%x\n",
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group->fanotify_data.flags & FANOTIFY_INIT_FLAGS,
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group->fanotify_data.f_flags);
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show_fdinfo(m, f, fanotify_fdinfo);
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}
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#endif /* CONFIG_FANOTIFY */
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#endif /* CONFIG_INOTIFY_USER || CONFIG_FANOTIFY */
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#endif /* CONFIG_PROC_FS */
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