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ecryptfs: use new start_creating/start_removing APIs 

This requires the addition of start_creating_dentry() which is given the
dentry which has already been found, and asks for it to be locked and
its parent validated.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-14-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
NeilBrown 2025-11-13 11:18:36 +11:00 committed by Christian Brauner
parent 833d2b3a07
commit f046fbb4d8
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
3 changed files with 107 additions and 81 deletions
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153
fs/ecryptfs/inode.c
View File

@ -24,18 +24,26 @@
#include <linux/unaligned.h>
#include "ecryptfs_kernel.h"
static int lock_parent(struct dentry *dentry,
struct dentry **lower_dentry,
struct inode **lower_dir)
static struct dentry *ecryptfs_start_creating_dentry(struct dentry *dentry)
{
struct dentry *lower_dir_dentry;
struct dentry *parent = dget_parent(dentry);
struct dentry *ret;
lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
*lower_dir = d_inode(lower_dir_dentry);
*lower_dentry = ecryptfs_dentry_to_lower(dentry);
ret = start_creating_dentry(ecryptfs_dentry_to_lower(parent),
ecryptfs_dentry_to_lower(dentry));
dput(parent);
return ret;
}
inode_lock_nested(*lower_dir, I_MUTEX_PARENT);
return (*lower_dentry)->d_parent == lower_dir_dentry ? 0 : -EINVAL;
static struct dentry *ecryptfs_start_removing_dentry(struct dentry *dentry)
{
struct dentry *parent = dget_parent(dentry);
struct dentry *ret;
ret = start_removing_dentry(ecryptfs_dentry_to_lower(parent),
ecryptfs_dentry_to_lower(dentry));
dput(parent);
return ret;
}
static int ecryptfs_inode_test(struct inode *inode, void *lower_inode)
@ -141,15 +149,12 @@ static int ecryptfs_do_unlink(struct inode *dir, struct dentry *dentry,
struct inode *lower_dir;
int rc;
rc = lock_parent(dentry, &lower_dentry, &lower_dir);
dget(lower_dentry); // don't even try to make the lower negative
if (!rc) {
if (d_unhashed(lower_dentry))
rc = -EINVAL;
else
rc = vfs_unlink(&nop_mnt_idmap, lower_dir, lower_dentry,
NULL);
}
lower_dentry = ecryptfs_start_removing_dentry(dentry);
if (IS_ERR(lower_dentry))
return PTR_ERR(lower_dentry);
lower_dir = lower_dentry->d_parent->d_inode;
rc = vfs_unlink(&nop_mnt_idmap, lower_dir, lower_dentry, NULL);
if (rc) {
printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
goto out_unlock;
@ -158,8 +163,7 @@ static int ecryptfs_do_unlink(struct inode *dir, struct dentry *dentry,
set_nlink(inode, ecryptfs_inode_to_lower(inode)->i_nlink);
inode_set_ctime_to_ts(inode, inode_get_ctime(dir));
out_unlock:
dput(lower_dentry);
inode_unlock(lower_dir);
end_removing(lower_dentry);
if (!rc)
d_drop(dentry);
return rc;
@ -186,10 +190,12 @@ ecryptfs_do_create(struct inode *directory_inode,
struct inode *lower_dir;
struct inode *inode;
rc = lock_parent(ecryptfs_dentry, &lower_dentry, &lower_dir);
if (!rc)
rc = vfs_create(&nop_mnt_idmap, lower_dir,
lower_dentry, mode, true);
lower_dentry = ecryptfs_start_creating_dentry(ecryptfs_dentry);
if (IS_ERR(lower_dentry))
return ERR_CAST(lower_dentry);
lower_dir = lower_dentry->d_parent->d_inode;
rc = vfs_create(&nop_mnt_idmap, lower_dir,
lower_dentry, mode, true);
if (rc) {
printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
"rc = [%d]\n", __func__, rc);
@ -205,7 +211,7 @@ ecryptfs_do_create(struct inode *directory_inode,
fsstack_copy_attr_times(directory_inode, lower_dir);
fsstack_copy_inode_size(directory_inode, lower_dir);
out_lock:
inode_unlock(lower_dir);
end_creating(lower_dentry, NULL);
return inode;
}
@ -433,10 +439,12 @@ static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
file_size_save = i_size_read(d_inode(old_dentry));
lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
rc = lock_parent(new_dentry, &lower_new_dentry, &lower_dir);
if (!rc)
rc = vfs_link(lower_old_dentry, &nop_mnt_idmap, lower_dir,
lower_new_dentry, NULL);
lower_new_dentry = ecryptfs_start_creating_dentry(new_dentry);
if (IS_ERR(lower_new_dentry))
return PTR_ERR(lower_new_dentry);
lower_dir = lower_new_dentry->d_parent->d_inode;
rc = vfs_link(lower_old_dentry, &nop_mnt_idmap, lower_dir,
lower_new_dentry, NULL);
if (rc || d_really_is_negative(lower_new_dentry))
goto out_lock;
rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb);
@ -448,7 +456,7 @@ static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
ecryptfs_inode_to_lower(d_inode(old_dentry))->i_nlink);
i_size_write(d_inode(new_dentry), file_size_save);
out_lock:
inode_unlock(lower_dir);
end_creating(lower_new_dentry, NULL);
return rc;
}
@ -468,9 +476,11 @@ static int ecryptfs_symlink(struct mnt_idmap *idmap,
size_t encoded_symlen;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
rc = lock_parent(dentry, &lower_dentry, &lower_dir);
if (rc)
goto out_lock;
lower_dentry = ecryptfs_start_creating_dentry(dentry);
if (IS_ERR(lower_dentry))
return PTR_ERR(lower_dentry);
lower_dir = lower_dentry->d_parent->d_inode;
mount_crypt_stat = &ecryptfs_superblock_to_private(
dir->i_sb)->mount_crypt_stat;
rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
@ -490,7 +500,7 @@ static int ecryptfs_symlink(struct mnt_idmap *idmap,
fsstack_copy_attr_times(dir, lower_dir);
fsstack_copy_inode_size(dir, lower_dir);
out_lock:
inode_unlock(lower_dir);
end_creating(lower_dentry, NULL);
if (d_really_is_negative(dentry))
d_drop(dentry);
return rc;
@ -501,12 +511,14 @@ static struct dentry *ecryptfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
{
int rc;
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry;
struct inode *lower_dir;
rc = lock_parent(dentry, &lower_dentry, &lower_dir);
if (rc)
goto out;
lower_dentry = ecryptfs_start_creating_dentry(dentry);
if (IS_ERR(lower_dentry))
return lower_dentry;
lower_dir_dentry = dget(lower_dentry->d_parent);
lower_dir = lower_dir_dentry->d_inode;
lower_dentry = vfs_mkdir(&nop_mnt_idmap, lower_dir,
lower_dentry, mode);
rc = PTR_ERR(lower_dentry);
@ -522,7 +534,7 @@ static struct dentry *ecryptfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
fsstack_copy_inode_size(dir, lower_dir);
set_nlink(dir, lower_dir->i_nlink);
out:
inode_unlock(lower_dir);
end_creating(lower_dentry, lower_dir_dentry);
if (d_really_is_negative(dentry))
d_drop(dentry);
return ERR_PTR(rc);
@ -534,21 +546,18 @@ static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
struct inode *lower_dir;
int rc;
rc = lock_parent(dentry, &lower_dentry, &lower_dir);
dget(lower_dentry); // don't even try to make the lower negative
if (!rc) {
if (d_unhashed(lower_dentry))
rc = -EINVAL;
else
rc = vfs_rmdir(&nop_mnt_idmap, lower_dir, lower_dentry);
}
lower_dentry = ecryptfs_start_removing_dentry(dentry);
if (IS_ERR(lower_dentry))
return PTR_ERR(lower_dentry);
lower_dir = lower_dentry->d_parent->d_inode;
rc = vfs_rmdir(&nop_mnt_idmap, lower_dir, lower_dentry);
if (!rc) {
clear_nlink(d_inode(dentry));
fsstack_copy_attr_times(dir, lower_dir);
set_nlink(dir, lower_dir->i_nlink);
}
dput(lower_dentry);
inode_unlock(lower_dir);
end_removing(lower_dentry);
if (!rc)
d_drop(dentry);
return rc;
@ -562,10 +571,12 @@ ecryptfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *lower_dentry;
struct inode *lower_dir;
rc = lock_parent(dentry, &lower_dentry, &lower_dir);
if (!rc)
rc = vfs_mknod(&nop_mnt_idmap, lower_dir,
lower_dentry, mode, dev);
lower_dentry = ecryptfs_start_creating_dentry(dentry);
if (IS_ERR(lower_dentry))
return PTR_ERR(lower_dentry);
lower_dir = lower_dentry->d_parent->d_inode;
rc = vfs_mknod(&nop_mnt_idmap, lower_dir, lower_dentry, mode, dev);
if (rc || d_really_is_negative(lower_dentry))
goto out;
rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
@ -574,7 +585,7 @@ ecryptfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
fsstack_copy_attr_times(dir, lower_dir);
fsstack_copy_inode_size(dir, lower_dir);
out:
inode_unlock(lower_dir);
end_removing(lower_dentry);
if (d_really_is_negative(dentry))
d_drop(dentry);
return rc;
@ -590,7 +601,6 @@ ecryptfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
struct dentry *lower_new_dentry;
struct dentry *lower_old_dir_dentry;
struct dentry *lower_new_dir_dentry;
struct dentry *trap;
struct inode *target_inode;
struct renamedata rd = {};
@ -605,31 +615,13 @@ ecryptfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
target_inode = d_inode(new_dentry);
trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
if (IS_ERR(trap))
return PTR_ERR(trap);
dget(lower_new_dentry);
rc = -EINVAL;
if (lower_old_dentry->d_parent != lower_old_dir_dentry)
goto out_lock;
if (lower_new_dentry->d_parent != lower_new_dir_dentry)
goto out_lock;
if (d_unhashed(lower_old_dentry) || d_unhashed(lower_new_dentry))
goto out_lock;
/* source should not be ancestor of target */
if (trap == lower_old_dentry)
goto out_lock;
/* target should not be ancestor of source */
if (trap == lower_new_dentry) {
rc = -ENOTEMPTY;
goto out_lock;
}
rd.mnt_idmap = &nop_mnt_idmap;
rd.old_parent = lower_old_dir_dentry;
rd.new_parent = lower_new_dir_dentry;
rc = start_renaming_two_dentries(&rd, lower_old_dentry, lower_new_dentry);
if (rc)
return rc;
rd.mnt_idmap = &nop_mnt_idmap;
rd.old_parent = lower_old_dir_dentry;
rd.old_dentry = lower_old_dentry;
rd.new_parent = lower_new_dir_dentry;
rd.new_dentry = lower_new_dentry;
rc = vfs_rename(&rd);
if (rc)
goto out_lock;
@ -640,8 +632,7 @@ ecryptfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
if (new_dir != old_dir)
fsstack_copy_attr_all(old_dir, d_inode(lower_old_dir_dentry));
out_lock:
dput(lower_new_dentry);
unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
end_renaming(&rd);
return rc;
}

33
fs/namei.c
View File

@ -3397,6 +3397,39 @@ struct dentry *start_removing_noperm(struct dentry *parent,
}
EXPORT_SYMBOL(start_removing_noperm);
/**
* start_creating_dentry - prepare to create a given dentry
* @parent: directory from which dentry should be removed
* @child: the dentry to be removed
*
* A lock is taken to protect the dentry again other dirops and
* the validity of the dentry is checked: correct parent and still hashed.
*
* If the dentry is valid and negative a reference is taken and
* returned. If not an error is returned.
*
* end_creating() should be called when creation is complete, or aborted.
*
* Returns: the valid dentry, or an error.
*/
struct dentry *start_creating_dentry(struct dentry *parent,
struct dentry *child)
{
inode_lock_nested(parent->d_inode, I_MUTEX_PARENT);
if (unlikely(IS_DEADDIR(parent->d_inode) ||
child->d_parent != parent ||
d_unhashed(child))) {
inode_unlock(parent->d_inode);
return ERR_PTR(-EINVAL);
}
if (d_is_positive(child)) {
inode_unlock(parent->d_inode);
return ERR_PTR(-EEXIST);
}
return dget(child);
}
EXPORT_SYMBOL(start_creating_dentry);
/**
* start_removing_dentry - prepare to remove a given dentry
* @parent: directory from which dentry should be removed

2
include/linux/namei.h
View File

@ -100,6 +100,8 @@ struct dentry *start_removing_killable(struct mnt_idmap *idmap,
struct qstr *name);
struct dentry *start_creating_noperm(struct dentry *parent, struct qstr *name);
struct dentry *start_removing_noperm(struct dentry *parent, struct qstr *name);
struct dentry *start_creating_dentry(struct dentry *parent,
struct dentry *child);
struct dentry *start_removing_dentry(struct dentry *parent,
struct dentry *child);