[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] fsdev: Don't ignore setfsuid/setfsgid return va
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH] fsdev: Don't ignore setfsuid/setfsgid return values |
Date: |
Fri, 05 Oct 2012 05:52:54 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 |
On 10/05/2012 02:36 AM, M. Mohan Kumar wrote:
> From: "M. Mohan Kumar" <address@hidden>
>
> In current implementation of setfsuid/setfsgid there is no way to know
> if it failed by checking the return value. This patch assumes
> setfsuid/setfsgid returns -1 in case of error. Eventually kernel code
> needs to be fixed.
According to the Fedora 17 man page:
RETURN VALUE
On success, the previous value of fsuid is returned. On error,
the current value of fsuid is returned.
NOTES
When glibc determines that the argument is not a valid user ID, it
will return -1 and set errno to EINVAL without attempting the system call.
BUGS
No error messages of any kind are returned to the caller. At the
very least, EPERM should be returned when the call fails (because the
caller lacks the CAP_SETUID capability).
Eww - self-contradictory. I think the reason that F17 marked these
functions warn_unused_return is because there HAS been an effort to make
these functions return sane values that can be used to detect when
errors have occurred.
>
> Signed-off-by: M. Mohan Kumar <address@hidden>
> ---
> fsdev/virtfs-proxy-helper.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/fsdev/virtfs-proxy-helper.c b/fsdev/virtfs-proxy-helper.c
> index f9a8270..ed5eede 100644
> --- a/fsdev/virtfs-proxy-helper.c
> +++ b/fsdev/virtfs-proxy-helper.c
> @@ -290,9 +290,12 @@ static int setfsugid(int uid, int gid)
> CAP_DAC_OVERRIDE,
> };
>
> - setfsgid(gid);
> - setfsuid(uid);
> -
> + if (setfsgid(gid) < 0) {
> + return -errno;
> + }
> + if (setfsuid(uid) < 0) {
> + return -errno;
> + }
At any rate, this silences the compiler warning I was hitting, so:
Tested-by: Eric Blake <address@hidden>
--
Eric Blake address@hidden +1-919-301-3266
Libvirt virtualization library http://libvirt.org
signature.asc
Description: OpenPGP digital signature