Check impure, opaque, origin & meta xattr with no sepolicy audit
(using __vfs_getxattr) since these operations are internal to
overlayfs operations and do not disclose any data. This became
an issue for credential override off since sys_admin would have
been required by the caller; whereas would have been inherently
present for the creator since it performed the mount.
This is a change in operations since we do not check in the new
ovl_vfs_getxattr function if the credential override is off or
not. Reasoning is that the sepolicy check is unnecessary overhead,
especially since the check can be expensive.
Signed-off-by: Mark Salyzyn <saly...@android.com>
Cc: Miklos Szeredi <mik...@szeredi.hu>
Cc: Jonathan Corbet <cor...@lwn.net>
Cc: Vivek Goyal <vgo...@redhat.com>
Cc: Eric W. Biederman <ebied...@xmission.com>
Cc: Amir Goldstein <amir7...@gmail.com>
Cc: Randy Dunlap <rdun...@infradead.org>
Cc: Stephen Smalley <s...@tycho.nsa.gov>
Cc: linux-unio...@vger.kernel.org
Cc: linux-...@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: kernel-t...@android.com
---
v10 - added to patch series
---
fs/overlayfs/namei.c | 12 +++++++-----
fs/overlayfs/overlayfs.h | 2 ++
fs/overlayfs/util.c | 24 +++++++++++++++---------
3 files changed, 24 insertions(+), 14 deletions(-)
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 9702f0d5309d..fb6c0cd7b65f 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -106,10 +106,11 @@ int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
static struct ovl_fh *ovl_get_fh(struct dentry *dentry, const char *name)
{
- int res, err;
+ ssize_t res;
+ int err;
struct ovl_fh *fh = NULL;
- res = vfs_getxattr(dentry, name, NULL, 0);
+ res = ovl_vfs_getxattr(dentry, name, NULL, 0);
if (res < 0) {
if (res == -ENODATA || res == -EOPNOTSUPP)
return NULL;
@@ -123,7 +124,7 @@ static struct ovl_fh *ovl_get_fh(struct dentry *dentry,
const char *name)
if (!fh)
return ERR_PTR(-ENOMEM);
- res = vfs_getxattr(dentry, name, fh, res);
+ res = ovl_vfs_getxattr(dentry, name, fh, res);
if (res < 0)
goto fail;
@@ -141,10 +142,11 @@ static struct ovl_fh *ovl_get_fh(struct dentry *dentry,
const char *name)
return NULL;
fail:
- pr_warn_ratelimited("overlayfs: failed to get origin (%i)\n", res);
+ pr_warn_ratelimited("overlayfs: failed to get origin (%zi)\n", res);
goto out;
invalid:
- pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n", res, fh);
+ pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n",
+ (int)res, fh);
goto out;
}
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 73a02a263fbc..82574684a9b6 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -205,6 +205,8 @@ int ovl_want_write(struct dentry *dentry);
void ovl_drop_write(struct dentry *dentry);
struct dentry *ovl_workdir(struct dentry *dentry);
const struct cred *ovl_override_creds(struct super_block *sb);
+ssize_t ovl_vfs_getxattr(struct dentry *dentry, const char *name, void *buf,
+ size_t size);
struct super_block *ovl_same_sb(struct super_block *sb);
int ovl_can_decode_fh(struct super_block *sb);
struct dentry *ovl_indexdir(struct super_block *sb);
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index f5678a3f8350..672459c3cff7 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -40,6 +40,12 @@ const struct cred *ovl_override_creds(struct super_block *sb)
return override_creds(ofs->creator_cred);
}
+ssize_t ovl_vfs_getxattr(struct dentry *dentry, const char *name, void *buf,
+ size_t size)
+{
+ return __vfs_getxattr(dentry, d_inode(dentry), name, buf, size);
+}
+
struct super_block *ovl_same_sb(struct super_block *sb)
{
struct ovl_fs *ofs = sb->s_fs_info;
@@ -537,9 +543,9 @@ void ovl_copy_up_end(struct dentry *dentry)
bool ovl_check_origin_xattr(struct dentry *dentry)
{
- int res;
+ ssize_t res;
- res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
+ res = ovl_vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
/* Zero size value means "copied up but origin unknown" */
if (res >= 0)
@@ -550,13 +556,13 @@ bool ovl_check_origin_xattr(struct dentry *dentry)
bool ovl_check_dir_xattr(struct dentry *dentry, const char *name)
{
- int res;
+ ssize_t res;
char val;
if (!d_is_dir(dentry))
return false;
- res = vfs_getxattr(dentry, name, &val, 1);
+ res = ovl_vfs_getxattr(dentry, name, &val, 1);
if (res == 1 && val == 'y')
return true;
@@ -837,13 +843,13 @@ int ovl_lock_rename_workdir(struct dentry *workdir,
struct dentry *upperdir)
/* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
int ovl_check_metacopy_xattr(struct dentry *dentry)
{
- int res;
+ ssize_t res;
/* Only regular files can have metacopy xattr */
if (!S_ISREG(d_inode(dentry)->i_mode))
return 0;
- res = vfs_getxattr(dentry, OVL_XATTR_METACOPY, NULL, 0);
+ res = ovl_vfs_getxattr(dentry, OVL_XATTR_METACOPY, NULL, 0);
if (res < 0) {
if (res == -ENODATA || res == -EOPNOTSUPP)
return 0;
@@ -852,7 +858,7 @@ int ovl_check_metacopy_xattr(struct dentry *dentry)
return 1;
out:
- pr_warn_ratelimited("overlayfs: failed to get metacopy (%i)\n", res);
+ pr_warn_ratelimited("overlayfs: failed to get metacopy (%zi)\n", res);
return res;
}
@@ -878,7 +884,7 @@ ssize_t ovl_getxattr(struct dentry *dentry, char *name,
char **value,
ssize_t res;
char *buf = NULL;
- res = vfs_getxattr(dentry, name, NULL, 0);
+ res = ovl_vfs_getxattr(dentry, name, NULL, 0);
if (res < 0) {
if (res == -ENODATA || res == -EOPNOTSUPP)
return -ENODATA;
@@ -890,7 +896,7 @@ ssize_t ovl_getxattr(struct dentry *dentry, char *name,
char **value,
if (!buf)
return -ENOMEM;
- res = vfs_getxattr(dentry, name, buf, res);
+ res = ovl_vfs_getxattr(dentry, name, buf, res);
if (res < 0)
goto fail;
}
--
2.22.0.657.g960e92d24f-goog
