From: Vivek Goyal <vgoyal@redhat.com>
To: linux-fsdevel@vger.kernel.org, miklos@szeredi.hu
Cc: vgoyal@redhat.com, virtio-fs@redhat.com
Subject: [PATCH v2 3/6] fuse: setattr should set FATTR_KILL_PRIV upon size change
Date: Wed, 16 Sep 2020 12:17:34 -0400 [thread overview]
Message-ID: <20200916161737.38028-4-vgoyal@redhat.com> (raw)
In-Reply-To: <20200916161737.38028-1-vgoyal@redhat.com>
If fc->handle_killpriv_v2 is enabled, we expect file server to clear
suid/sgid/security.capbility upon chown/truncate/write as appropriate.
Upon truncate (ATTR_SIZE), suid/sgid is cleared only if caller does
not have CAP_FSETID. File server does not know whether caller has
CAP_FSETID or not. Hence set FATTR_KILL_PRIV upon truncate to let
file server know that caller does not have CAP_FSETID and it should
kill suid/sgid as appropriate.
We don't have to send this information for chown (ATTR_UID/ATTR_GID)
as that always clears suid/sgid irrespective of capabilities of
calling process.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
fs/fuse/dir.c | 2 ++
include/uapi/linux/fuse.h | 1 +
2 files changed, 3 insertions(+)
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index c4a01290aec6..ecdb7895c156 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1575,6 +1575,8 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
/* For mandatory locking in truncate */
inarg.valid |= FATTR_LOCKOWNER;
inarg.lock_owner = fuse_lock_owner_id(fc, current->files);
+ if (fc->handle_killpriv_v2 && !capable(CAP_FSETID))
+ inarg.valid |= FATTR_KILL_PRIV;
}
fuse_setattr_fill(fc, &args, inode, &inarg, &outarg);
err = fuse_simple_request(fc, &args);
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 3ae3f222a0ed..7b8da0a2de0d 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -269,6 +269,7 @@ struct fuse_file_lock {
#define FATTR_MTIME_NOW (1 << 8)
#define FATTR_LOCKOWNER (1 << 9)
#define FATTR_CTIME (1 << 10)
+#define FATTR_KILL_PRIV (1 << 14) /* Matches ATTR_KILL_PRIV */
/**
* Flags returned by the OPEN request
--
2.25.4
next prev parent reply other threads:[~2020-09-16 20:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 16:17 [PATCH v2 0/6] fuse: Implement FUSE_HANDLE_KILLPRIV_V2 and enable SB_NOSEC Vivek Goyal
2020-09-16 16:17 ` [PATCH v2 1/6] fuse: Introduce the notion of FUSE_HANDLE_KILLPRIV_V2 Vivek Goyal
2020-09-16 16:17 ` [PATCH v2 2/6] fuse: Set FUSE_WRITE_KILL_PRIV in cached write path Vivek Goyal
2020-09-16 16:17 ` Vivek Goyal [this message]
2020-09-16 16:17 ` [PATCH v2 4/6] fuse: Kill suid/sgid using ATTR_MODE if it is not truncate Vivek Goyal
2020-09-22 13:56 ` Miklos Szeredi
2020-09-22 20:08 ` Vivek Goyal
2020-09-22 21:25 ` Miklos Szeredi
2020-09-22 21:31 ` Vivek Goyal
2020-09-16 16:17 ` [PATCH v2 5/6] fuse: Add a flag FUSE_OPEN_KILL_PRIV for open() request Vivek Goyal
2020-09-16 16:17 ` [PATCH v2 6/6] virtiofs: Support SB_NOSEC flag to improve direct write performance Vivek Goyal
2020-09-16 16:38 ` [PATCH v2 0/6] fuse: Implement FUSE_HANDLE_KILLPRIV_V2 and enable SB_NOSEC Vivek Goyal
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