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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2017-01-10 21:30:21 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2017-02-07 15:47:14 +0100
commit51f8f3c4e22535933ef9aecc00e9a6069e051b57 (patch)
treeb5ca89d2ee7d508616995e9b68792fb8363e844c
parente593b2bf513dd4d3fbfa0f435392eea2c7f776f0 (diff)
downloadlinux-stericsson-51f8f3c4e22535933ef9aecc00e9a6069e051b57.tar.gz
ovl: drop CAP_SYS_RESOURCE from saved mounter's credentials
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: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Fixes: 1175b6b8d963 ("ovl: do operations on underlying file system in mounter's context") Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
-rw-r--r--fs/overlayfs/super.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 346f668e7df0..7b2188181367 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -721,6 +721,7 @@ 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;
@@ -901,10 +902,13 @@ 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)