[PATCH v4 34/54] selinuxfs: new helper for attaching files to tree

Al Viro
2025-11-18T05:20:02Z

allocating dentry after the inode has been set up reduces the amount
of boilerplate - "attach this inode under that name and this parent
or drop inode in case of failure" simplifies quite a few places.

Acked-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Tested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
security/selinux/selinuxfs.c | 160 +++++++++++++++--------------------
1 file changed, 66 insertions(+), 94 deletions(-)

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index b39e919c27b1..f088776dbbd3 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -1197,6 +1197,25 @@ static struct inode *sel_make_inode(struct super_block *sb, umode_t mode)
return ret;
}

+static struct dentry *sel_attach(struct dentry *parent, const char *name,
+ struct inode *inode)
+{
+ struct dentry *dentry = d_alloc_name(parent, name);
+ if (unlikely(!dentry)) {
+ iput(inode);
+ return ERR_PTR(-ENOMEM);
+ }
+ d_add(dentry, inode);
+ return dentry;
+}
+
+static int sel_attach_file(struct dentry *parent, const char *name,
+ struct inode *inode)
+{
+ struct dentry *dentry = sel_attach(parent, name, inode);
+ return PTR_ERR_OR_ZERO(dentry);
+}
+
static ssize_t sel_read_bool(struct file *filep, char __user *buf,
size_t count, loff_t *ppos)
{
@@ -1356,8 +1375,7 @@ static int sel_make_bools(struct selinux_policy *newpolicy, struct dentry *bool_
*bool_num = num;
*bool_pending_names = names;

- for (i = 0; i < num; i++) {
- struct dentry *dentry;
+ for (i = 0; !ret && i < num; i++) {
struct inode *inode;
struct inode_security_struct *isec;
ssize_t len;
@@ -1368,15 +1386,9 @@ static int sel_make_bools(struct selinux_policy *newpolicy, struct dentry *bool_
ret = -ENAMETOOLONG;
break;
}
- dentry = d_alloc_name(bool_dir, names[i]);
- if (!dentry) {
- ret = -ENOMEM;
- break;
- }

inode = sel_make_inode(bool_dir->d_sb, S_IFREG | S_IRUGO | S_IWUSR);
if (!inode) {
- dput(dentry);
ret = -ENOMEM;
break;
}
@@ -1394,7 +1406,8 @@ static int sel_make_bools(struct selinux_policy *newpolicy, struct dentry *bool_
isec->initialized = LABEL_INITIALIZED;
inode->i_fop = &sel_bool_ops;
inode->i_ino = i|SEL_BOOL_INO_OFFSET;
- d_add(dentry, inode);
+
+ ret = sel_attach_file(bool_dir, names[i], inode);
}
out:
free_page((unsigned long)page);
@@ -1579,6 +1592,7 @@ static int sel_make_avc_files(struct dentry *dir)
struct super_block *sb = dir->d_sb;
struct selinux_fs_info *fsi = sb->s_fs_info;
unsigned int i;
+ int err = 0;
static const struct tree_descr files[] = {
{ "cache_threshold",
&sel_avc_cache_threshold_ops, S_IRUGO|S_IWUSR },
@@ -1588,26 +1602,20 @@ static int sel_make_avc_files(struct dentry *dir)
#endif
};

- for (i = 0; i < ARRAY_SIZE(files); i++) {
+ for (i = 0; !err && i < ARRAY_SIZE(files); i++) {
struct inode *inode;
- struct dentry *dentry;
-
- dentry = d_alloc_name(dir, files[i].name);
- if (!dentry)
- return -ENOMEM;

inode = sel_make_inode(dir->d_sb, S_IFREG|files[i].mode);
- if (!inode) {
- dput(dentry);
+ if (!inode)
return -ENOMEM;
- }

inode->i_fop = files[i].ops;
inode->i_ino = ++fsi->last_ino;
- d_add(dentry, inode);
+
+ err = sel_attach_file(dir, files[i].name, inode);
}

- return 0;
+ return err;
}

static int sel_make_ss_files(struct dentry *dir)
@@ -1615,30 +1623,25 @@ static int sel_make_ss_files(struct dentry *dir)
struct super_block *sb = dir->d_sb;
struct selinux_fs_info *fsi = sb->s_fs_info;
unsigned int i;
+ int err = 0;
static const struct tree_descr files[] = {
{ "sidtab_hash_stats", &sel_sidtab_hash_stats_ops, S_IRUGO },
};

- for (i = 0; i < ARRAY_SIZE(files); i++) {
+ for (i = 0; !err && i < ARRAY_SIZE(files); i++) {
struct inode *inode;
- struct dentry *dentry;
-
- dentry = d_alloc_name(dir, files[i].name);
- if (!dentry)
- return -ENOMEM;

inode = sel_make_inode(dir->d_sb, S_IFREG|files[i].mode);
- if (!inode) {
- dput(dentry);
+ if (!inode)
return -ENOMEM;
- }

inode->i_fop = files[i].ops;
inode->i_ino = ++fsi->last_ino;
- d_add(dentry, inode);
+
+ err = sel_attach_file(dir, files[i].name, inode);
}

- return 0;
+ return err;
}

static ssize_t sel_read_initcon(struct file *file, char __user *buf,
@@ -1666,30 +1669,25 @@ static const struct file_operations sel_initcon_ops = {
static int sel_make_initcon_files(struct dentry *dir)
{
unsigned int i;
+ int err = 0;

- for (i = 1; i <= SECINITSID_NUM; i++) {
- struct inode *inode;
- struct dentry *dentry;
+ for (i = 1; !err && i <= SECINITSID_NUM; i++) {
const char *s = security_get_initial_sid_context(i);
+ struct inode *inode;

if (!s)
continue;
- dentry = d_alloc_name(dir, s);
- if (!dentry)
- return -ENOMEM;

inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO);
- if (!inode) {
- dput(dentry);
+ if (!inode)
return -ENOMEM;
- }

inode->i_fop = &sel_initcon_ops;
inode->i_ino = i|SEL_INITCON_INO_OFFSET;
- d_add(dentry, inode);
+ err = sel_attach_file(dir, s, inode);
}

- return 0;
+ return err;
}

static inline unsigned long sel_class_to_ino(u16 class)
@@ -1771,29 +1769,21 @@ static int sel_make_perm_files(struct selinux_policy *newpolicy,
if (rc)
return rc;

- for (i = 0; i < nperms; i++) {
+ for (i = 0; !rc && i < nperms; i++) {
struct inode *inode;
- struct dentry *dentry;

- rc = -ENOMEM;
- dentry = d_alloc_name(dir, perms[i]);
- if (!dentry)
- goto out;
-
- rc = -ENOMEM;
inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO);
if (!inode) {
- dput(dentry);
- goto out;
+ rc = -ENOMEM;
+ break;
}

inode->i_fop = &sel_perm_ops;
/* i+1 since perm values are 1-indexed */
inode->i_ino = sel_perm_to_ino(classvalue, i + 1);
- d_add(dentry, inode);
+
+ rc = sel_attach_file(dir, perms[i], inode);
}
- rc = 0;
-out:
for (i = 0; i < nperms; i++)
kfree(perms[i]);
kfree(perms);
@@ -1808,20 +1798,18 @@ static int sel_make_class_dir_entries(struct selinux_policy *newpolicy,
struct selinux_fs_info *fsi = sb->s_fs_info;
struct dentry *dentry = NULL;
struct inode *inode = NULL;
-
- dentry = d_alloc_name(dir, "index");
- if (!dentry)
- return -ENOMEM;
+ int err;

inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO);
- if (!inode) {
- dput(dentry);
+ if (!inode)
return -ENOMEM;
- }

inode->i_fop = &sel_class_ops;
inode->i_ino = sel_class_to_ino(index);
- d_add(dentry, inode);
+
+ err = sel_attach_file(dir, "index", inode);
+ if (err)
+ return err;

dentry = sel_make_dir(dir, "perms", &fsi->last_class_ino);
if (IS_ERR(dentry))
@@ -1873,58 +1861,47 @@ static int sel_make_policycap(struct dentry *dir)
{
struct super_block *sb = dir->d_sb;
unsigned int iter;
- struct dentry *dentry = NULL;
struct inode *inode = NULL;
+ int err = 0;
+
+ for (iter = 0; !err && iter <= POLICYDB_CAP_MAX; iter++) {
+ const char *name;

- for (iter = 0; iter <= POLICYDB_CAP_MAX; iter++) {
if (iter < ARRAY_SIZE(selinux_policycap_names))
- dentry = d_alloc_name(dir,
- selinux_policycap_names[iter]);
+ name = selinux_policycap_names[iter];
else
- dentry = d_alloc_name(dir, "unknown");
-
- if (dentry == NULL)
- return -ENOMEM;
+ name = "unknown";

inode = sel_make_inode(sb, S_IFREG | 0444);
- if (inode == NULL) {
- dput(dentry);
+ if (!inode)
return -ENOMEM;
- }

inode->i_fop = &sel_policycap_ops;
inode->i_ino = iter | SEL_POLICYCAP_INO_OFFSET;
- d_add(dentry, inode);
+ err = sel_attach_file(dir, name, inode);
}

- return 0;
+ return err;
}

static struct dentry *sel_make_dir(struct dentry *dir, const char *name,
unsigned long *ino)
{
- struct dentry *dentry = d_alloc_name(dir, name);
struct inode *inode;

- if (!dentry)
- return ERR_PTR(-ENOMEM);
-
inode = sel_make_inode(dir->d_sb, S_IFDIR | S_IRUGO | S_IXUGO);
- if (!inode) {
- dput(dentry);
+ if (!inode)
return ERR_PTR(-ENOMEM);
- }

inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
inode->i_ino = ++(*ino);
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
- d_add(dentry, inode);
/* bump link count on parent directory, too */
inc_nlink(d_inode(dir));

- return dentry;
+ return sel_attach(dir, name, inode);
}

static int reject_all(struct mnt_idmap *idmap, struct inode *inode, int mask)
@@ -2012,17 +1989,10 @@ static int sel_fill_super(struct super_block *sb, struct fs_context *fc)
goto err;
}

- ret = -ENOMEM;
- dentry = d_alloc_name(sb->s_root, NULL_FILE_NAME);
- if (!dentry)
- goto err;
-
ret = -ENOMEM;
inode = sel_make_inode(sb, S_IFCHR | S_IRUGO | S_IWUGO);
- if (!inode) {
- dput(dentry);
+ if (!inode)
goto err;
- }

inode->i_ino = ++fsi->last_ino;
isec = selinux_inode(inode);
@@ -2031,7 +2001,9 @@ static int sel_fill_super(struct super_block *sb, struct fs_context *fc)
isec->initialized = LABEL_INITIALIZED;

init_special_inode(inode, S_IFCHR | S_IRUGO | S_IWUGO, MKDEV(MEM_MAJOR, 3));
- d_add(dentry, inode);
+ ret = sel_attach_file(sb->s_root, NULL_FILE_NAME, inode);
+ if (ret)
+ goto err;

dentry = sel_make_dir(sb->s_root, "avc", &fsi->last_ino);
if (IS_ERR(dentry)) {
--
2.47.3