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introduce cloning of fs_context

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new primitive: vfs_dup_fs_context().  Comes with fs_context
method (->dup()) for copying the filesystem-specific parts
of fs_context, along with LSM one (->fs_context_dup()) for
doing the same to LSM parts.

[needs better commit message, and change of Author:, anyway]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2018-12-23 16:02:47 -05:00
parent cb50b348c7
commit 0b52075ee6
7 changed files with 175 additions and 0 deletions
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2
include/linux/fs_context.h
View file

@ -94,6 +94,7 @@ struct fs_context {
struct fs_context_operations {
void (*free)(struct fs_context *fc);
int (*dup)(struct fs_context *fc, struct fs_context *src_fc);
int (*parse_param)(struct fs_context *fc, struct fs_parameter *param);
int (*parse_monolithic)(struct fs_context *fc, void *data);
int (*get_tree)(struct fs_context *fc);
@ -111,6 +112,7 @@ extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type,
struct dentry *reference);
extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc);
extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param);
extern int vfs_parse_fs_string(struct fs_context *fc, const char *key,
const char *value, size_t v_size);

7
include/linux/lsm_hooks.h
View file

@ -79,6 +79,11 @@
* Security hooks for mount using fs_context.
* [See also Documentation/filesystems/mounting.txt]
*
* @fs_context_dup:
* Allocate and attach a security structure to sc->security. This pointer
* is initialised to NULL by the caller.
* @fc indicates the new filesystem context.
* @src_fc indicates the original filesystem context.
* @fs_context_parse_param:
* Userspace provided a parameter to configure a superblock. The LSM may
* reject it with an error and may use it for itself, in which case it
@ -1470,6 +1475,7 @@ union security_list_options {
void (*bprm_committing_creds)(struct linux_binprm *bprm);
void (*bprm_committed_creds)(struct linux_binprm *bprm);
int (*fs_context_dup)(struct fs_context *fc, struct fs_context *src_sc);
int (*fs_context_parse_param)(struct fs_context *fc, struct fs_parameter *param);
int (*sb_alloc_security)(struct super_block *sb);
@ -1813,6 +1819,7 @@ struct security_hook_heads {
struct hlist_head bprm_check_security;
struct hlist_head bprm_committing_creds;
struct hlist_head bprm_committed_creds;
struct hlist_head fs_context_dup;
struct hlist_head fs_context_parse_param;
struct hlist_head sb_alloc_security;
struct hlist_head sb_free_security;

6
include/linux/security.h
View file

@ -223,6 +223,7 @@ int security_bprm_set_creds(struct linux_binprm *bprm);
int security_bprm_check(struct linux_binprm *bprm);
void security_bprm_committing_creds(struct linux_binprm *bprm);
void security_bprm_committed_creds(struct linux_binprm *bprm);
int security_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc);
int security_fs_context_parse_param(struct fs_context *fc, struct fs_parameter *param);
int security_sb_alloc(struct super_block *sb);
void security_sb_free(struct super_block *sb);
@ -521,6 +522,11 @@ static inline void security_bprm_committed_creds(struct linux_binprm *bprm)
{
}
static inline int security_fs_context_dup(struct fs_context *fc,
struct fs_context *src_fc)
{
return 0;
}
static inline int security_fs_context_parse_param(struct fs_context *fc,
struct fs_parameter *param)
{