FUSE doesn't seem to be adding the FUSE_WRITE_KILL_SUIDGID flag on write
requests for FUSE connections that support FUSE_HANDLE_KILLPRIV but not
FUSE_HANDLE_KILLPRIV_V2.
However, the FUSE userspace header states:
FUSE_HANDLE_KILLPRIV: fs handles killing suid/sgid/cap on
write/chown/trunc
^^^^^
To improve backwards compatibility with file servers that don't support
FUSE_HANDLE_KILLPRIV_V2, add the FUSE_WRITE_KILL_SUIDGID flag to write
requests if FUSE_HANDLE_KILLPRIV has been negotiated -OR- if the
conditions for FUSE_HANDLE_KILLPRIV_V2 support are met.
Signed-off-by: Connor Kuehl <[email protected]>
---
fs/fuse/file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 8cccecb55fb8..7dc9182d1ece 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1106,7 +1106,7 @@ static ssize_t fuse_send_write_pages(struct fuse_io_args *ia,
fuse_write_args_fill(ia, ff, pos, count);
ia->write.in.flags = fuse_write_flags(iocb);
- if (fm->fc->handle_killpriv_v2 && !capable(CAP_FSETID))
+ if (fm->fc->handle_killpriv || (fm->fc->handle_killpriv_v2 && !capable(CAP_FSETID)))
ia->write.in.write_flags |= FUSE_WRITE_KILL_SUIDGID;
err = fuse_simple_request(fm, &ap->args);
--
2.30.2
On Fri, 23 Apr 2021 at 17:19, Connor Kuehl <[email protected]> wrote:
>
> FUSE doesn't seem to be adding the FUSE_WRITE_KILL_SUIDGID flag on write
> requests for FUSE connections that support FUSE_HANDLE_KILLPRIV but not
> FUSE_HANDLE_KILLPRIV_V2.
>
> However, the FUSE userspace header states:
>
> FUSE_HANDLE_KILLPRIV: fs handles killing suid/sgid/cap on
> write/chown/trunc
> ^^^^^
>
> To improve backwards compatibility with file servers that don't support
> FUSE_HANDLE_KILLPRIV_V2, add the FUSE_WRITE_KILL_SUIDGID flag to write
> requests if FUSE_HANDLE_KILLPRIV has been negotiated -OR- if the
> conditions for FUSE_HANDLE_KILLPRIV_V2 support are met.
If server does not support FUSE_HANDLE_KILLPRIV_V2, then it does not
support FUSE_WRITE_KILL_SUIDGID either. The two were introduced
together and the latter is only meaningful if the
FUSE_HANDLE_KILLPRIV_V2 feature was negotiated.
What am I missing?
Thanks,
Miklos
On 6/21/21 3:26 AM, Miklos Szeredi wrote:
> On Fri, 23 Apr 2021 at 17:19, Connor Kuehl <[email protected]> wrote:
>>
>> FUSE doesn't seem to be adding the FUSE_WRITE_KILL_SUIDGID flag on write
>> requests for FUSE connections that support FUSE_HANDLE_KILLPRIV but not
>> FUSE_HANDLE_KILLPRIV_V2.
>>
>> However, the FUSE userspace header states:
>>
>> FUSE_HANDLE_KILLPRIV: fs handles killing suid/sgid/cap on
>> write/chown/trunc
>> ^^^^^
>>
>> To improve backwards compatibility with file servers that don't support
>> FUSE_HANDLE_KILLPRIV_V2, add the FUSE_WRITE_KILL_SUIDGID flag to write
>> requests if FUSE_HANDLE_KILLPRIV has been negotiated -OR- if the
>> conditions for FUSE_HANDLE_KILLPRIV_V2 support are met.
>
>
> If server does not support FUSE_HANDLE_KILLPRIV_V2, then it does not
> support FUSE_WRITE_KILL_SUIDGID either. The two were introduced
> together and the latter is only meaningful if the
> FUSE_HANDLE_KILLPRIV_V2 feature was negotiated.
>
> What am I missing?
You're not missing anything, this patch is wrong. Let's nack this.
Thanks!
Connor