The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 2d8ae8c417db284f598dffb178cc01e7db0f1821 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023071623-graceful-breeder-217d@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: 2d8ae8c417db ("nfsd: use vfs setgid helper") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 2d8ae8c417db284f598dffb178cc01e7db0f1821 Mon Sep 17 00:00:00 2001 From: Christian Brauner <brauner@xxxxxxxxxx> Date: Tue, 2 May 2023 15:36:02 +0200 Subject: [PATCH] nfsd: use vfs setgid helper We've aligned setgid behavior over multiple kernel releases. The details can be found in commit cf619f891971 ("Merge tag 'fs.ovl.setgid.v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping") and commit 426b4ca2d6a5 ("Merge tag 'fs.setgid.v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux"). Consistent setgid stripping behavior is now encapsulated in the setattr_should_drop_sgid() helper which is used by all filesystems that strip setgid bits outside of vfs proper. Usually ATTR_KILL_SGID is raised in e.g., chown_common() and is subject to the setattr_should_drop_sgid() check to determine whether the setgid bit can be retained. Since nfsd is raising ATTR_KILL_SGID unconditionally it will cause notify_change() to strip it even if the caller had the necessary privileges to retain it. Ensure that nfsd only raises ATR_KILL_SGID if the caller lacks the necessary privileges to retain the setgid bit. Without this patch the setgid stripping tests in LTP will fail: > As you can see, the problem is S_ISGID (0002000) was dropped on a > non-group-executable file while chown was invoked by super-user, while [...] > fchown02.c:66: TFAIL: testfile2: wrong mode permissions 0100700, expected 0102700 [...] > chown02.c:57: TFAIL: testfile2: wrong mode permissions 0100700, expected 0102700 With this patch all tests pass. Reported-by: Sherry Yang <sherry.yang@xxxxxxxxxx> Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index db67f8e19344..0016bcc04a59 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -388,7 +388,9 @@ nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap) iap->ia_mode &= ~S_ISGID; } else { /* set ATTR_KILL_* bits and let VFS handle it */ - iap->ia_valid |= (ATTR_KILL_SUID | ATTR_KILL_SGID); + iap->ia_valid |= ATTR_KILL_SUID; + iap->ia_valid |= + setattr_should_drop_sgid(&nop_mnt_idmap, inode); } } }
