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ovl: port ovl_lower_positive() to cred guard 

Use the scoped ovl cred guard.

Link: https://patch.msgid.link/20251117-work-ovl-cred-guard-v4-39-b31603935724@kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2025-11-17 10:34:10 +01:00
parent 6b6ef7d16f
commit db7cfe8783
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GPG Key ID: 91C61BC06578DCA2
1 changed files with 34 additions and 36 deletions
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70
fs/overlayfs/namei.c
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@ -1418,7 +1418,6 @@ bool ovl_lower_positive(struct dentry *dentry)
{ {
struct ovl_entry *poe = OVL_E(dentry->d_parent); struct ovl_entry *poe = OVL_E(dentry->d_parent);
const struct qstr *name = &dentry->d_name; const struct qstr *name = &dentry->d_name;
const struct cred *old_cred;
unsigned int i; unsigned int i;
bool positive = false; bool positive = false;
bool done = false; bool done = false;
@ -1434,46 +1433,45 @@ bool ovl_lower_positive(struct dentry *dentry)
if (!ovl_dentry_upper(dentry)) if (!ovl_dentry_upper(dentry))
return true; return true;
old_cred = ovl_override_creds(dentry->d_sb); with_ovl_creds(dentry->d_sb) {
/* Positive upper -> have to look up lower to see whether it exists */ /* Positive upper -> have to look up lower to see whether it exists */
for (i = 0; !done && !positive && i < ovl_numlower(poe); i++) { for (i = 0; !done && !positive && i < ovl_numlower(poe); i++) {
struct dentry *this; struct dentry *this;
struct ovl_path *parentpath = &ovl_lowerstack(poe)[i]; struct ovl_path *parentpath = &ovl_lowerstack(poe)[i];
/* /*
* We need to make a non-const copy of dentry->d_name, * We need to make a non-const copy of dentry->d_name,
* because lookup_one_positive_unlocked() will hash name * because lookup_one_positive_unlocked() will hash name
* with parentpath base, which is on another (lower fs). * with parentpath base, which is on another (lower fs).
*/ */
this = lookup_one_positive_unlocked( this = lookup_one_positive_unlocked(mnt_idmap(parentpath->layer->mnt),
mnt_idmap(parentpath->layer->mnt), &QSTR_LEN(name->name, name->len),
&QSTR_LEN(name->name, name->len), parentpath->dentry);
parentpath->dentry); if (IS_ERR(this)) {
if (IS_ERR(this)) { switch (PTR_ERR(this)) {
switch (PTR_ERR(this)) { case -ENOENT:
case -ENOENT: case -ENAMETOOLONG:
case -ENAMETOOLONG: break;
break;
default: default:
/* /*
* Assume something is there, we just couldn't * Assume something is there, we just couldn't
* access it. * access it.
*/ */
positive = true; positive = true;
break; break;
}
} else {
struct path path = {
.dentry = this,
.mnt = parentpath->layer->mnt,
};
positive = !ovl_path_is_whiteout(OVL_FS(dentry->d_sb), &path);
done = true;
dput(this);
} }
} else {
struct path path = {
.dentry = this,
.mnt = parentpath->layer->mnt,
};
positive = !ovl_path_is_whiteout(OVL_FS(dentry->d_sb), &path);
done = true;
dput(this);
} }
} }
ovl_revert_creds(old_cred);
return positive; return positive;
} }