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Message-ID: <20240822012523.141846-12-vinicius.gomes@intel.com>
Date: Wed, 21 Aug 2024 18:25:18 -0700
From: Vinicius Costa Gomes <vinicius.gomes@...el.com>
To: brauner@...nel.org,
amir73il@...il.com,
hu1.chen@...el.com
Cc: miklos@...redi.hu,
malini.bhandaru@...el.com,
tim.c.chen@...el.com,
mikko.ylinen@...el.com,
lizhen.you@...el.com,
linux-unionfs@...r.kernel.org,
linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org,
Vinicius Costa Gomes <vinicius.gomes@...el.com>
Subject: [PATCH v2 11/16] overlayfs/inode: Convert to cred_guard()
Replace the override_creds_light()/revert_creds_light() pairs of
operations with cred_guard()/cred_scoped_guard().
In ovl_setattr(), ovl_set_or_remove_acl() and ovl_fileattr_set() use
cred_scoped_guard(), because of 'goto', which can cause the cleanup
flow to run on garbage memory.
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
---
fs/overlayfs/inode.c | 73 +++++++++++++++++---------------------------
1 file changed, 28 insertions(+), 45 deletions(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 30460d718605..a597e748397f 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -25,7 +25,6 @@ int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
bool full_copy_up = false;
struct dentry *upperdentry;
- const struct cred *old_cred;
err = setattr_prepare(&nop_mnt_idmap, dentry, attr);
if (err)
@@ -78,9 +77,8 @@ int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
goto out_put_write;
inode_lock(upperdentry->d_inode);
- old_cred = ovl_override_creds_light(dentry->d_sb);
- err = ovl_do_notify_change(ofs, upperdentry, attr);
- revert_creds_light(old_cred);
+ cred_scoped_guard(ovl_creds(dentry->d_sb))
+ err = ovl_do_notify_change(ofs, upperdentry, attr);
if (!err)
ovl_copyattr(dentry->d_inode);
inode_unlock(upperdentry->d_inode);
@@ -159,7 +157,6 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
struct dentry *dentry = path->dentry;
enum ovl_path_type type;
struct path realpath;
- const struct cred *old_cred;
struct inode *inode = d_inode(dentry);
bool is_dir = S_ISDIR(inode->i_mode);
int fsid = 0;
@@ -169,7 +166,7 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
metacopy_blocks = ovl_is_metacopy_dentry(dentry);
type = ovl_path_real(dentry, &realpath);
- old_cred = ovl_override_creds_light(dentry->d_sb);
+ cred_guard(ovl_creds(dentry->d_sb));
err = ovl_do_getattr(&realpath, stat, request_mask, flags);
if (err)
goto out;
@@ -280,7 +277,6 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
stat->nlink = dentry->d_inode->i_nlink;
out:
- revert_creds_light(old_cred);
return err;
}
@@ -291,7 +287,6 @@ int ovl_permission(struct mnt_idmap *idmap,
struct inode *upperinode = ovl_inode_upper(inode);
struct inode *realinode;
struct path realpath;
- const struct cred *old_cred;
int err;
/* Careful in RCU walk mode */
@@ -309,7 +304,7 @@ int ovl_permission(struct mnt_idmap *idmap,
if (err)
return err;
- old_cred = ovl_override_creds_light(inode->i_sb);
+ cred_guard(ovl_creds(inode->i_sb));
if (!upperinode &&
!special_file(realinode->i_mode) && mask & MAY_WRITE) {
mask &= ~(MAY_WRITE | MAY_APPEND);
@@ -317,7 +312,6 @@ int ovl_permission(struct mnt_idmap *idmap,
mask |= MAY_READ;
}
err = inode_permission(mnt_idmap(realpath.mnt), realinode, mask);
- revert_creds_light(old_cred);
return err;
}
@@ -326,15 +320,13 @@ static const char *ovl_get_link(struct dentry *dentry,
struct inode *inode,
struct delayed_call *done)
{
- const struct cred *old_cred;
const char *p;
if (!dentry)
return ERR_PTR(-ECHILD);
- old_cred = ovl_override_creds_light(dentry->d_sb);
+ cred_guard(ovl_creds(dentry->d_sb));
p = vfs_get_link(ovl_dentry_real(dentry), done);
- revert_creds_light(old_cred);
return p;
}
@@ -465,11 +457,9 @@ struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap,
acl = get_cached_acl_rcu(realinode, type);
} else {
- const struct cred *old_cred;
- old_cred = ovl_override_creds_light(inode->i_sb);
+ cred_guard(ovl_creds(inode->i_sb));
acl = ovl_get_acl_path(&realpath, posix_acl_xattr_name(type), noperm);
- revert_creds_light(old_cred);
}
return acl;
@@ -481,7 +471,6 @@ static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
int err;
struct path realpath;
const char *acl_name;
- const struct cred *old_cred;
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct dentry *upperdentry = ovl_dentry_upper(dentry);
struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
@@ -495,10 +484,9 @@ static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
struct posix_acl *real_acl;
ovl_path_lower(dentry, &realpath);
- old_cred = ovl_override_creds_light(dentry->d_sb);
+ cred_guard(ovl_creds(dentry->d_sb));
real_acl = vfs_get_acl(mnt_idmap(realpath.mnt), realdentry,
acl_name);
- revert_creds_light(old_cred);
if (IS_ERR(real_acl)) {
err = PTR_ERR(real_acl);
goto out;
@@ -518,12 +506,12 @@ static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
if (err)
goto out;
- old_cred = ovl_override_creds_light(dentry->d_sb);
- if (acl)
- err = ovl_do_set_acl(ofs, realdentry, acl_name, acl);
- else
- err = ovl_do_remove_acl(ofs, realdentry, acl_name);
- revert_creds_light(old_cred);
+ cred_scoped_guard(ovl_creds(dentry->d_sb)) {
+ if (acl)
+ err = ovl_do_set_acl(ofs, realdentry, acl_name, acl);
+ else
+ err = ovl_do_remove_acl(ofs, realdentry, acl_name);
+ }
ovl_drop_write(dentry);
/* copy c/mtime */
@@ -590,7 +578,6 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
{
int err;
struct inode *realinode = ovl_inode_realdata(inode);
- const struct cred *old_cred;
if (!realinode)
return -EIO;
@@ -598,9 +585,8 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
if (!realinode->i_op->fiemap)
return -EOPNOTSUPP;
- old_cred = ovl_override_creds_light(inode->i_sb);
+ cred_guard(ovl_creds(inode->i_sb));
err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
- revert_creds_light(old_cred);
return err;
}
@@ -648,7 +634,6 @@ int ovl_fileattr_set(struct mnt_idmap *idmap,
{
struct inode *inode = d_inode(dentry);
struct path upperpath;
- const struct cred *old_cred;
unsigned int flags;
int err;
@@ -660,19 +645,19 @@ int ovl_fileattr_set(struct mnt_idmap *idmap,
if (err)
goto out;
- old_cred = ovl_override_creds_light(inode->i_sb);
- /*
- * Store immutable/append-only flags in xattr and clear them
- * in upper fileattr (in case they were set by older kernel)
- * so children of "ovl-immutable" directories lower aliases of
- * "ovl-immutable" hardlinks could be copied up.
- * Clear xattr when flags are cleared.
- */
- err = ovl_set_protattr(inode, upperpath.dentry, fa);
- if (!err)
- err = ovl_real_fileattr_set(&upperpath, fa);
- revert_creds_light(old_cred);
- ovl_drop_write(dentry);
+ cred_scoped_guard(ovl_creds(inode->i_sb)) {
+ /*
+ * Store immutable/append-only flags in xattr and clear them
+ * in upper fileattr (in case they were set by older kernel)
+ * so children of "ovl-immutable" directories lower aliases of
+ * "ovl-immutable" hardlinks could be copied up.
+ * Clear xattr when flags are cleared.
+ */
+ err = ovl_set_protattr(inode, upperpath.dentry, fa);
+ if (!err)
+ err = ovl_real_fileattr_set(&upperpath, fa);
+ ovl_drop_write(dentry);
+ }
/*
* Merge real inode flags with inode flags read from
@@ -725,15 +710,13 @@ int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa)
{
struct inode *inode = d_inode(dentry);
struct path realpath;
- const struct cred *old_cred;
int err;
ovl_path_real(dentry, &realpath);
- old_cred = ovl_override_creds_light(inode->i_sb);
+ cred_guard(ovl_creds(inode->i_sb));
err = ovl_real_fileattr_get(&realpath, fa);
ovl_fileattr_prot_flags(inode, fa);
- revert_creds_light(old_cred);
return err;
}
--
2.46.0
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