From 4f0b9194bc119a9850a99e5e824808e2f468c348 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 3 Nov 2023 06:47:51 -0400 Subject: fs: Rename anon_inode_getfile_secure() and anon_inode_getfd_secure() The call to the inode_init_security_anon() LSM hook is not the sole reason to use anon_inode_getfile_secure() or anon_inode_getfd_secure(). For example, the functions also allow one to create a file with non-zero size, without needing a full-blown filesystem. In this case, you don't need a "secure" version, just unique inodes; the current name of the functions is confusing and does not explain well the difference with the more "standard" anon_inode_getfile() and anon_inode_getfd(). Of course, there is another side of the coin; neither io_uring nor userfaultfd strictly speaking need distinct inodes, and it is not that clear anymore that anon_inode_create_get{file,fd}() allow the LSM to intercept and block the inode's creation. If one was so inclined, anon_inode_getfile_secure() and anon_inode_getfd_secure() could be kept, using the shared inode or a new one depending on CONFIG_SECURITY. However, this is probably overkill, and potentially a cause of bugs in different configurations. Therefore, just add a comment to io_uring and userfaultfd explaining the choice of the function. While at it, remove the export for what is now anon_inode_create_getfd(). There is no in-tree module that uses it, and the old name is gone anyway. If anybody actually needs the symbol, they can ask or they can just use anon_inode_create_getfile(), which will be exported very soon for use in KVM. Suggested-by: Christian Brauner Reviewed-by: Christian Brauner Signed-off-by: Paolo Bonzini --- fs/anon_inodes.c | 50 +++++++++++++++++++++++++++++++++----------------- 1 file changed, 33 insertions(+), 17 deletions(-) (limited to 'fs/anon_inodes.c') diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index 24192a7667ed..42b02dc36474 100644 --- a/fs/anon_inodes.c +++ b/fs/anon_inodes.c @@ -79,7 +79,7 @@ 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; @@ -87,7 +87,7 @@ static struct file *__anon_inode_getfile(const char *name, if (fops->owner && !try_module_get(fops->owner)) return ERR_PTR(-ENOENT); - if (secure) { + if (make_inode) { inode = anon_inode_make_secure_inode(name, context_inode); if (IS_ERR(inode)) { file = ERR_CAST(inode); @@ -149,13 +149,10 @@ 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_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 +161,21 @@ 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) @@ -181,7 +188,7 @@ 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 +199,7 @@ 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 +238,9 @@ 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 +249,26 @@ 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) { -- cgit