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Commit fee760fc authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by Greg Kroah-Hartman
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ovl: drop CAP_SYS_RESOURCE from saved mounter's credentials 



commit 51f8f3c4e22535933ef9aecc00e9a6069e051b57 upstream.

If overlay was mounted by root then quota set for upper layer does not work
because overlay now always use mounter's credentials for operations.
Also overlay might deplete reserved space and inodes in ext4.

This patch drops capability SYS_RESOURCE from saved credentials.
This affects creation new files, whiteouts, and copy-up operations.

Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: 1175b6b8 ("ovl: do operations on underlying file system in mounter's context")
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0fb615f9

fs/overlayfs/super.c

+6 −2
Original line number Diff line number Diff line
@@ -1146,6 +1146,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
	unsigned int stacklen = 0;

	unsigned int i;

	bool remote = false;

	struct cred *cred;

	int err;



	err = -ENOMEM;
@@ -1309,10 +1310,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
	else

		sb->s_d_op = &ovl_dentry_operations;



	ufs->creator_cred = prepare_creds();

	if (!ufs->creator_cred)

	ufs->creator_cred = cred = prepare_creds();

	if (!cred)

		goto out_put_lower_mnt;



	/* Never override disk quota limits or use reserved space */

	cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);



	err = -ENOMEM;

	oe = ovl_alloc_entry(numlower);

	if (!oe)