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Diffstat (limited to 'fs/anon_inodes.c')
-rw-r--r--fs/anon_inodes.c115
1 files changed, 89 insertions, 26 deletions
diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 24192a7667ed..35f765610802 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -24,8 +24,8 @@
#include <linux/uaccess.h>
-static struct vfsmount *anon_inode_mnt __read_mostly;
-static struct inode *anon_inode_inode;
+static struct vfsmount *anon_inode_mnt __ro_after_init;
+static struct inode *anon_inode_inode __ro_after_init;
/*
* anon_inodefs_dname() is called from d_path().
@@ -55,31 +55,43 @@ static struct file_system_type anon_inode_fs_type = {
.kill_sb = kill_anon_super,
};
-static struct inode *anon_inode_make_secure_inode(
- const char *name,
- const struct inode *context_inode)
+/**
+ * anon_inode_make_secure_inode - allocate an anonymous inode with security context
+ * @sb: [in] Superblock to allocate from
+ * @name: [in] Name of the class of the newfile (e.g., "secretmem")
+ * @context_inode:
+ * [in] Optional parent inode for security inheritance
+ *
+ * The function ensures proper security initialization through the LSM hook
+ * security_inode_init_security_anon().
+ *
+ * Return: Pointer to new inode on success, ERR_PTR on failure.
+ */
+struct inode *anon_inode_make_secure_inode(struct super_block *sb, const char *name,
+ const struct inode *context_inode)
{
struct inode *inode;
- const struct qstr qname = QSTR_INIT(name, strlen(name));
int error;
- inode = alloc_anon_inode(anon_inode_mnt->mnt_sb);
+ inode = alloc_anon_inode(sb);
if (IS_ERR(inode))
return inode;
inode->i_flags &= ~S_PRIVATE;
- error = security_inode_init_security_anon(inode, &qname, context_inode);
+ error = security_inode_init_security_anon(inode, &QSTR(name),
+ context_inode);
if (error) {
iput(inode);
return ERR_PTR(error);
}
return inode;
}
+EXPORT_SYMBOL_GPL_FOR_MODULES(anon_inode_make_secure_inode, "kvm");
static struct file *__anon_inode_getfile(const char *name,
const struct file_operations *fops,
void *priv, int flags,
const struct inode *context_inode,
- bool secure)
+ bool make_inode)
{
struct inode *inode;
struct file *file;
@@ -87,8 +99,9 @@ static struct file *__anon_inode_getfile(const char *name,
if (fops->owner && !try_module_get(fops->owner))
return ERR_PTR(-ENOENT);
- if (secure) {
- inode = anon_inode_make_secure_inode(name, context_inode);
+ if (make_inode) {
+ inode = anon_inode_make_secure_inode(anon_inode_mnt->mnt_sb,
+ name, context_inode);
if (IS_ERR(inode)) {
file = ERR_CAST(inode);
goto err;
@@ -149,13 +162,42 @@ struct file *anon_inode_getfile(const char *name,
EXPORT_SYMBOL_GPL(anon_inode_getfile);
/**
- * anon_inode_getfile_secure - Like anon_inode_getfile(), but creates a new
+ * anon_inode_getfile_fmode - creates a new file instance by hooking it up to an
+ * anonymous inode, and a dentry that describe the "class"
+ * of the file
+ *
+ * @name: [in] name of the "class" of the new file
+ * @fops: [in] file operations for the new file
+ * @priv: [in] private data for the new file (will be file's private_data)
+ * @flags: [in] flags
+ * @f_mode: [in] fmode
+ *
+ * Creates a new file by hooking it on a single inode. This is useful for files
+ * that do not need to have a full-fledged inode in order to operate correctly.
+ * All the files created with anon_inode_getfile() will share a single inode,
+ * hence saving memory and avoiding code duplication for the file/inode/dentry
+ * setup. Allows setting the fmode. Returns the newly created file* or an error
+ * pointer.
+ */
+struct file *anon_inode_getfile_fmode(const char *name,
+ const struct file_operations *fops,
+ void *priv, int flags, fmode_t f_mode)
+{
+ struct file *file;
+
+ file = __anon_inode_getfile(name, fops, priv, flags, NULL, false);
+ if (!IS_ERR(file))
+ file->f_mode |= f_mode;
+
+ return file;
+}
+EXPORT_SYMBOL_GPL(anon_inode_getfile_fmode);
+
+/**
+ * anon_inode_create_getfile - Like anon_inode_getfile(), but creates a new
* !S_PRIVATE anon inode rather than reuse the
* singleton anon inode and calls the
- * inode_init_security_anon() LSM hook. This
- * allows for both the inode to have its own
- * security context and for the LSM to enforce
- * policy on the inode's creation.
+ * inode_init_security_anon() LSM hook.
*
* @name: [in] name of the "class" of the new file
* @fops: [in] file operations for the new file
@@ -164,11 +206,21 @@ EXPORT_SYMBOL_GPL(anon_inode_getfile);
* @context_inode:
* [in] the logical relationship with the new inode (optional)
*
+ * Create a new anonymous inode and file pair. This can be done for two
+ * reasons:
+ *
+ * - for the inode to have its own security context, so that LSMs can enforce
+ * policy on the inode's creation;
+ *
+ * - if the caller needs a unique inode, for example in order to customize
+ * the size returned by fstat()
+ *
* The LSM may use @context_inode in inode_init_security_anon(), but a
- * reference to it is not held. Returns the newly created file* or an error
- * pointer. See the anon_inode_getfile() documentation for more information.
+ * reference to it is not held.
+ *
+ * Returns the newly created file* or an error pointer.
*/
-struct file *anon_inode_getfile_secure(const char *name,
+struct file *anon_inode_create_getfile(const char *name,
const struct file_operations *fops,
void *priv, int flags,
const struct inode *context_inode)
@@ -176,12 +228,13 @@ struct file *anon_inode_getfile_secure(const char *name,
return __anon_inode_getfile(name, fops, priv, flags,
context_inode, true);
}
+EXPORT_SYMBOL_GPL(anon_inode_create_getfile);
static int __anon_inode_getfd(const char *name,
const struct file_operations *fops,
void *priv, int flags,
const struct inode *context_inode,
- bool secure)
+ bool make_inode)
{
int error, fd;
struct file *file;
@@ -192,7 +245,7 @@ static int __anon_inode_getfd(const char *name,
fd = error;
file = __anon_inode_getfile(name, fops, priv, flags, context_inode,
- secure);
+ make_inode);
if (IS_ERR(file)) {
error = PTR_ERR(file);
goto err_put_unused_fd;
@@ -231,10 +284,9 @@ int anon_inode_getfd(const char *name, const struct file_operations *fops,
EXPORT_SYMBOL_GPL(anon_inode_getfd);
/**
- * anon_inode_getfd_secure - Like anon_inode_getfd(), but creates a new
+ * anon_inode_create_getfd - Like anon_inode_getfd(), but creates a new
* !S_PRIVATE anon inode rather than reuse the singleton anon inode, and calls
- * the inode_init_security_anon() LSM hook. This allows the inode to have its
- * own security context and for a LSM to reject creation of the inode.
+ * the inode_init_security_anon() LSM hook.
*
* @name: [in] name of the "class" of the new file
* @fops: [in] file operations for the new file
@@ -243,16 +295,27 @@ EXPORT_SYMBOL_GPL(anon_inode_getfd);
* @context_inode:
* [in] the logical relationship with the new inode (optional)
*
+ * Create a new anonymous inode and file pair. This can be done for two
+ * reasons:
+ *
+ * - for the inode to have its own security context, so that LSMs can enforce
+ * policy on the inode's creation;
+ *
+ * - if the caller needs a unique inode, for example in order to customize
+ * the size returned by fstat()
+ *
* The LSM may use @context_inode in inode_init_security_anon(), but a
* reference to it is not held.
+ *
+ * Returns a newly created file descriptor or an error code.
*/
-int anon_inode_getfd_secure(const char *name, const struct file_operations *fops,
+int anon_inode_create_getfd(const char *name, const struct file_operations *fops,
void *priv, int flags,
const struct inode *context_inode)
{
return __anon_inode_getfd(name, fops, priv, flags, context_inode, true);
}
-EXPORT_SYMBOL_GPL(anon_inode_getfd_secure);
+
static int __init anon_inode_init(void)
{
generated by cgit v1.2.3 (git 2.39.0) at 2025-08-30 01:51:36 +0300