diff options
| author | Vivek Goyal <vgoyal@redhat.com> | 2021-03-25 11:18:23 -0400 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2021-04-14 10:40:57 +0200 |
| commit | 550a7d3bc0c4049ef8d36ff4d9ed7082ee8cb5ec (patch) | |
| tree | 7d2266a677214950a303ae1eb69803a0faeff9c4 | |
| parent | 52a4c95f4d24b8bcb50745732f7b9f8513c49c5f (diff) | |
| download | linux-rpi-550a7d3bc0c4049ef8d36ff4d9ed7082ee8cb5ec.tar.gz linux-rpi-550a7d3bc0c4049ef8d36ff4d9ed7082ee8cb5ec.tar.bz2 linux-rpi-550a7d3bc0c4049ef8d36ff4d9ed7082ee8cb5ec.zip | |
fuse: add a flag FUSE_SETXATTR_ACL_KILL_SGID to kill SGID
When posix access ACL is set, it can have an effect on file mode and it can
also need to clear SGID if.
- None of caller's group/supplementary groups match file owner group.
AND
- Caller is not priviliged (No CAP_FSETID).
As of now fuser server is responsible for changing the file mode as
well. But it does not know whether to clear SGID or not.
So add a flag FUSE_SETXATTR_ACL_KILL_SGID and send this info with SETXATTR
to let file server know that sgid needs to be cleared as well.
Reported-by: Luis Henriques <lhenriques@suse.de>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
| -rw-r--r-- | fs/fuse/acl.c | 7 | ||||
| -rw-r--r-- | include/uapi/linux/fuse.h | 7 |
2 files changed, 13 insertions, 1 deletions
diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c index d31260a139d4..52b165319be1 100644 --- a/fs/fuse/acl.c +++ b/fs/fuse/acl.c @@ -71,6 +71,7 @@ int fuse_set_acl(struct user_namespace *mnt_userns, struct inode *inode, return -EINVAL; if (acl) { + unsigned int extra_flags = 0; /* * Fuse userspace is responsible for updating access * permissions in the inode, if needed. fuse_setxattr @@ -94,7 +95,11 @@ int fuse_set_acl(struct user_namespace *mnt_userns, struct inode *inode, return ret; } - ret = fuse_setxattr(inode, name, value, size, 0, 0); + if (!in_group_p(i_gid_into_mnt(&init_user_ns, inode)) && + !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID)) + extra_flags |= FUSE_SETXATTR_ACL_KILL_SGID; + + ret = fuse_setxattr(inode, name, value, size, 0, extra_flags); kfree(value); } else { ret = fuse_removexattr(inode, name); diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 390f7b4c889d..271ae90a9bb7 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -180,6 +180,7 @@ * - add FUSE_HANDLE_KILLPRIV_V2, FUSE_WRITE_KILL_SUIDGID, FATTR_KILL_SUIDGID * - add FUSE_OPEN_KILL_SUIDGID * - extend fuse_setxattr_in, add FUSE_SETXATTR_EXT + * - add FUSE_SETXATTR_ACL_KILL_SGID */ #ifndef _LINUX_FUSE_H @@ -454,6 +455,12 @@ struct fuse_file_lock { */ #define FUSE_OPEN_KILL_SUIDGID (1 << 0) +/** + * setxattr flags + * FUSE_SETXATTR_ACL_KILL_SGID: Clear SGID when system.posix_acl_access is set + */ +#define FUSE_SETXATTR_ACL_KILL_SGID (1 << 0) + enum fuse_opcode { FUSE_LOOKUP = 1, FUSE_FORGET = 2, /* no reply */ |