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ovl: lookup: do getxattr with mounter's permission

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The getxattr() in ovl_is_opaquedir() was missed when converting all
operations on underlying fs to be done under mounter's permission.

This patch fixes this by moving the ovl_override_creds()/revert_creds() out
from ovl_lookup_real() to ovl_lookup().

Also convert to using vfs_getxattr() instead of directly calling
i_op->getxattr().

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi 2016-09-16 14:12:11 +02:00
parent 8b326c61de
commit 2b6bc7f48d
1 changed files with 9 additions and 11 deletions
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20
fs/overlayfs/super.c
View file

@ -273,12 +273,11 @@ static bool ovl_is_opaquedir(struct dentry *dentry)
{
int res;
char val;
struct inode *inode = dentry->d_inode;
if (!S_ISDIR(inode->i_mode) || !inode->i_op->getxattr)
if (!d_is_dir(dentry))
return false;
res = inode->i_op->getxattr(dentry, inode, OVL_XATTR_OPAQUE, &val, 1);
res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1);
if (res == 1 && val == 'y')
return true;
@ -419,16 +418,12 @@ static bool ovl_dentry_weird(struct dentry *dentry)
DCACHE_OP_COMPARE);
}
static inline struct dentry *ovl_lookup_real(struct super_block *ovl_sb,
struct dentry *dir,
static inline struct dentry *ovl_lookup_real(struct dentry *dir,
const struct qstr *name)
{
const struct cred *old_cred;
struct dentry *dentry;
old_cred = ovl_override_creds(ovl_sb);
dentry = lookup_one_len_unlocked(name->name, dir, name->len);
revert_creds(old_cred);
if (IS_ERR(dentry)) {
if (PTR_ERR(dentry) == -ENOENT)
@ -469,6 +464,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct ovl_entry *oe;
const struct cred *old_cred;
struct ovl_entry *poe = dentry->d_parent->d_fsdata;
struct path *stack = NULL;
struct dentry *upperdir, *upperdentry = NULL;
@ -479,9 +475,10 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int i;
int err;
old_cred = ovl_override_creds(dentry->d_sb);
upperdir = ovl_upperdentry_dereference(poe);
if (upperdir) {
this = ovl_lookup_real(dentry->d_sb, upperdir, &dentry->d_name);
this = ovl_lookup_real(upperdir, &dentry->d_name);
err = PTR_ERR(this);
if (IS_ERR(this))
goto out;
@ -514,8 +511,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
bool opaque = false;
struct path lowerpath = poe->lowerstack[i];
this = ovl_lookup_real(dentry->d_sb,
lowerpath.dentry, &dentry->d_name);
this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
err = PTR_ERR(this);
if (IS_ERR(this)) {
/*
@ -588,6 +584,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
ovl_copyattr(realdentry->d_inode, inode);
}
revert_creds(old_cred);
oe->opaque = upperopaque;
oe->__upperdentry = upperdentry;
memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
@ -606,6 +603,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
out_put_upper:
dput(upperdentry);
out:
revert_creds(old_cred);
return ERR_PTR(err);
}