1e1743ebe3
This simple implementation just checks for no ACLs on the inode, and if so, then the rcu-walk may proceed, otherwise fail it. This could easily be extended to put acls under RCU and check them under seqlock, if need be. But this implementation is enough to show the rcu-walk aware permissions code for path lookups is working, and will handle cases where there are no ACLs or ACLs in just the final element. This patch implicity converts tmpfs to rcu-aware permission check. Subsequent patches onvert ext*, xfs, and, btrfs. Each of these uses acl/permission code in a different way, so convert them all to provide templates and proof of concept. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
194 lines
4.2 KiB
C
194 lines
4.2 KiB
C
/*
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File: linux/posix_acl.h
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(C) 2002 Andreas Gruenbacher, <a.gruenbacher@computer.org>
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*/
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#ifndef __LINUX_POSIX_ACL_H
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#define __LINUX_POSIX_ACL_H
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#include <linux/slab.h>
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#define ACL_UNDEFINED_ID (-1)
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/* a_type field in acl_user_posix_entry_t */
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#define ACL_TYPE_ACCESS (0x8000)
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#define ACL_TYPE_DEFAULT (0x4000)
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/* e_tag entry in struct posix_acl_entry */
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#define ACL_USER_OBJ (0x01)
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#define ACL_USER (0x02)
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#define ACL_GROUP_OBJ (0x04)
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#define ACL_GROUP (0x08)
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#define ACL_MASK (0x10)
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#define ACL_OTHER (0x20)
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/* permissions in the e_perm field */
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#define ACL_READ (0x04)
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#define ACL_WRITE (0x02)
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#define ACL_EXECUTE (0x01)
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//#define ACL_ADD (0x08)
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//#define ACL_DELETE (0x10)
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struct posix_acl_entry {
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short e_tag;
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unsigned short e_perm;
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unsigned int e_id;
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};
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struct posix_acl {
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atomic_t a_refcount;
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unsigned int a_count;
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struct posix_acl_entry a_entries[0];
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};
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#define FOREACH_ACL_ENTRY(pa, acl, pe) \
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for(pa=(acl)->a_entries, pe=pa+(acl)->a_count; pa<pe; pa++)
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/*
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* Duplicate an ACL handle.
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*/
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static inline struct posix_acl *
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posix_acl_dup(struct posix_acl *acl)
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{
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if (acl)
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atomic_inc(&acl->a_refcount);
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return acl;
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}
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/*
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* Free an ACL handle.
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*/
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static inline void
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posix_acl_release(struct posix_acl *acl)
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{
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if (acl && atomic_dec_and_test(&acl->a_refcount))
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kfree(acl);
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}
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/* posix_acl.c */
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extern struct posix_acl *posix_acl_alloc(int, gfp_t);
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extern struct posix_acl *posix_acl_clone(const struct posix_acl *, gfp_t);
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extern int posix_acl_valid(const struct posix_acl *);
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extern int posix_acl_permission(struct inode *, const struct posix_acl *, int);
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extern struct posix_acl *posix_acl_from_mode(mode_t, gfp_t);
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extern int posix_acl_equiv_mode(const struct posix_acl *, mode_t *);
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extern int posix_acl_create_masq(struct posix_acl *, mode_t *);
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extern int posix_acl_chmod_masq(struct posix_acl *, mode_t);
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extern struct posix_acl *get_posix_acl(struct inode *, int);
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extern int set_posix_acl(struct inode *, int, struct posix_acl *);
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#ifdef CONFIG_FS_POSIX_ACL
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static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
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{
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struct posix_acl **p, *acl;
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switch (type) {
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case ACL_TYPE_ACCESS:
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p = &inode->i_acl;
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break;
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case ACL_TYPE_DEFAULT:
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p = &inode->i_default_acl;
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break;
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default:
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return ERR_PTR(-EINVAL);
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}
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acl = ACCESS_ONCE(*p);
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if (acl) {
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spin_lock(&inode->i_lock);
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acl = *p;
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if (acl != ACL_NOT_CACHED)
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acl = posix_acl_dup(acl);
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spin_unlock(&inode->i_lock);
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}
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return acl;
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}
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static inline int negative_cached_acl(struct inode *inode, int type)
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{
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struct posix_acl **p, *acl;
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switch (type) {
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case ACL_TYPE_ACCESS:
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p = &inode->i_acl;
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break;
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case ACL_TYPE_DEFAULT:
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p = &inode->i_default_acl;
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break;
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default:
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BUG();
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}
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acl = ACCESS_ONCE(*p);
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if (acl)
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return 0;
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return 1;
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}
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static inline void set_cached_acl(struct inode *inode,
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int type,
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struct posix_acl *acl)
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{
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struct posix_acl *old = NULL;
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spin_lock(&inode->i_lock);
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switch (type) {
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case ACL_TYPE_ACCESS:
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old = inode->i_acl;
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inode->i_acl = posix_acl_dup(acl);
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break;
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case ACL_TYPE_DEFAULT:
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old = inode->i_default_acl;
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inode->i_default_acl = posix_acl_dup(acl);
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break;
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}
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spin_unlock(&inode->i_lock);
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if (old != ACL_NOT_CACHED)
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posix_acl_release(old);
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}
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static inline void forget_cached_acl(struct inode *inode, int type)
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{
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struct posix_acl *old = NULL;
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spin_lock(&inode->i_lock);
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switch (type) {
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case ACL_TYPE_ACCESS:
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old = inode->i_acl;
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inode->i_acl = ACL_NOT_CACHED;
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break;
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case ACL_TYPE_DEFAULT:
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old = inode->i_default_acl;
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inode->i_default_acl = ACL_NOT_CACHED;
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break;
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}
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spin_unlock(&inode->i_lock);
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if (old != ACL_NOT_CACHED)
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posix_acl_release(old);
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}
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static inline void forget_all_cached_acls(struct inode *inode)
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{
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struct posix_acl *old_access, *old_default;
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spin_lock(&inode->i_lock);
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old_access = inode->i_acl;
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old_default = inode->i_default_acl;
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inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
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spin_unlock(&inode->i_lock);
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if (old_access != ACL_NOT_CACHED)
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posix_acl_release(old_access);
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if (old_default != ACL_NOT_CACHED)
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posix_acl_release(old_default);
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}
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#endif
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static inline void cache_no_acl(struct inode *inode)
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{
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#ifdef CONFIG_FS_POSIX_ACL
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inode->i_acl = NULL;
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inode->i_default_acl = NULL;
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#endif
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}
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#endif /* __LINUX_POSIX_ACL_H */
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