diff options
Diffstat (limited to 'fs/posix_acl.c')
| -rw-r--r-- | fs/posix_acl.c | 1254 |
1 files changed, 1254 insertions, 0 deletions
diff --git a/fs/posix_acl.c b/fs/posix_acl.c new file mode 100644 index 000000000..74dc0f571 --- /dev/null +++ b/fs/posix_acl.c @@ -0,0 +1,1254 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org> + * + * Fixes from William Schumacher incorporated on 15 March 2001. + * (Reported by Charles Bertsch, <CBertsch@microtest.com>). + */ + +/* + * This file contains generic functions for manipulating + * POSIX 1003.1e draft standard 17 ACLs. + */ + +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/atomic.h> +#include <linux/fs.h> +#include <linux/sched.h> +#include <linux/cred.h> +#include <linux/posix_acl.h> +#include <linux/posix_acl_xattr.h> +#include <linux/xattr.h> +#include <linux/export.h> +#include <linux/user_namespace.h> +#include <linux/namei.h> +#include <linux/mnt_idmapping.h> +#include <linux/iversion.h> + +static struct posix_acl **acl_by_type(struct inode *inode, int type) +{ + switch (type) { + case ACL_TYPE_ACCESS: + return &inode->i_acl; + case ACL_TYPE_DEFAULT: + return &inode->i_default_acl; + default: + BUG(); + } +} + +struct posix_acl *get_cached_acl(struct inode *inode, int type) +{ + struct posix_acl **p = acl_by_type(inode, type); + struct posix_acl *acl; + + for (;;) { + rcu_read_lock(); + acl = rcu_dereference(*p); + if (!acl || is_uncached_acl(acl) || + refcount_inc_not_zero(&acl->a_refcount)) + break; + rcu_read_unlock(); + cpu_relax(); + } + rcu_read_unlock(); + return acl; +} +EXPORT_SYMBOL(get_cached_acl); + +struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type) +{ + struct posix_acl *acl = rcu_dereference(*acl_by_type(inode, type)); + + if (acl == ACL_DONT_CACHE) { + struct posix_acl *ret; + + ret = inode->i_op->get_acl(inode, type, LOOKUP_RCU); + if (!IS_ERR(ret)) + acl = ret; + } + + return acl; +} +EXPORT_SYMBOL(get_cached_acl_rcu); + +void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl) +{ + struct posix_acl **p = acl_by_type(inode, type); + struct posix_acl *old; + + old = xchg(p, posix_acl_dup(acl)); + if (!is_uncached_acl(old)) + posix_acl_release(old); +} +EXPORT_SYMBOL(set_cached_acl); + +static void __forget_cached_acl(struct posix_acl **p) +{ + struct posix_acl *old; + + old = xchg(p, ACL_NOT_CACHED); + if (!is_uncached_acl(old)) + posix_acl_release(old); +} + +void forget_cached_acl(struct inode *inode, int type) +{ + __forget_cached_acl(acl_by_type(inode, type)); +} +EXPORT_SYMBOL(forget_cached_acl); + +void forget_all_cached_acls(struct inode *inode) +{ + __forget_cached_acl(&inode->i_acl); + __forget_cached_acl(&inode->i_default_acl); +} +EXPORT_SYMBOL(forget_all_cached_acls); + +struct posix_acl *get_acl(struct inode *inode, int type) +{ + void *sentinel; + struct posix_acl **p; + struct posix_acl *acl; + + /* + * The sentinel is used to detect when another operation like + * set_cached_acl() or forget_cached_acl() races with get_acl(). + * It is guaranteed that is_uncached_acl(sentinel) is true. + */ + + acl = get_cached_acl(inode, type); + if (!is_uncached_acl(acl)) + return acl; + + if (!IS_POSIXACL(inode)) + return NULL; + + sentinel = uncached_acl_sentinel(current); + p = acl_by_type(inode, type); + + /* + * If the ACL isn't being read yet, set our sentinel. Otherwise, the + * current value of the ACL will not be ACL_NOT_CACHED and so our own + * sentinel will not be set; another task will update the cache. We + * could wait for that other task to complete its job, but it's easier + * to just call ->get_acl to fetch the ACL ourself. (This is going to + * be an unlikely race.) + */ + cmpxchg(p, ACL_NOT_CACHED, sentinel); + + /* + * Normally, the ACL returned by ->get_acl will be cached. + * A filesystem can prevent that by calling + * forget_cached_acl(inode, type) in ->get_acl. + * + * If the filesystem doesn't have a get_acl() function at all, we'll + * just create the negative cache entry. + */ + if (!inode->i_op->get_acl) { + set_cached_acl(inode, type, NULL); + return NULL; + } + acl = inode->i_op->get_acl(inode, type, false); + + if (IS_ERR(acl)) { + /* + * Remove our sentinel so that we don't block future attempts + * to cache the ACL. + */ + cmpxchg(p, sentinel, ACL_NOT_CACHED); + return acl; + } + + /* + * Cache the result, but only if our sentinel is still in place. + */ + posix_acl_dup(acl); + if (unlikely(cmpxchg(p, sentinel, acl) != sentinel)) + posix_acl_release(acl); + return acl; +} +EXPORT_SYMBOL(get_acl); + +/* + * Init a fresh posix_acl + */ +void +posix_acl_init(struct posix_acl *acl, int count) +{ + refcount_set(&acl->a_refcount, 1); + acl->a_count = count; +} +EXPORT_SYMBOL(posix_acl_init); + +/* + * Allocate a new ACL with the specified number of entries. + */ +struct posix_acl * +posix_acl_alloc(int count, gfp_t flags) +{ + const size_t size = sizeof(struct posix_acl) + + count * sizeof(struct posix_acl_entry); + struct posix_acl *acl = kmalloc(size, flags); + if (acl) + posix_acl_init(acl, count); + return acl; +} +EXPORT_SYMBOL(posix_acl_alloc); + +/* + * Clone an ACL. + */ +struct posix_acl * +posix_acl_clone(const struct posix_acl *acl, gfp_t flags) +{ + struct posix_acl *clone = NULL; + + if (acl) { + int size = sizeof(struct posix_acl) + acl->a_count * + sizeof(struct posix_acl_entry); + clone = kmemdup(acl, size, flags); + if (clone) + refcount_set(&clone->a_refcount, 1); + } + return clone; +} +EXPORT_SYMBOL_GPL(posix_acl_clone); + +/* + * Check if an acl is valid. Returns 0 if it is, or -E... otherwise. + */ +int +posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl) +{ + const struct posix_acl_entry *pa, *pe; + int state = ACL_USER_OBJ; + int needs_mask = 0; + + FOREACH_ACL_ENTRY(pa, acl, pe) { + if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE)) + return -EINVAL; + switch (pa->e_tag) { + case ACL_USER_OBJ: + if (state == ACL_USER_OBJ) { + state = ACL_USER; + break; + } + return -EINVAL; + + case ACL_USER: + if (state != ACL_USER) + return -EINVAL; + if (!kuid_has_mapping(user_ns, pa->e_uid)) + return -EINVAL; + needs_mask = 1; + break; + + case ACL_GROUP_OBJ: + if (state == ACL_USER) { + state = ACL_GROUP; + break; + } + return -EINVAL; + + case ACL_GROUP: + if (state != ACL_GROUP) + return -EINVAL; + if (!kgid_has_mapping(user_ns, pa->e_gid)) + return -EINVAL; + needs_mask = 1; + break; + + case ACL_MASK: + if (state != ACL_GROUP) + return -EINVAL; + state = ACL_OTHER; + break; + + case ACL_OTHER: + if (state == ACL_OTHER || + (state == ACL_GROUP && !needs_mask)) { + state = 0; + break; + } + return -EINVAL; + + default: + return -EINVAL; + } + } + if (state == 0) + return 0; + return -EINVAL; +} +EXPORT_SYMBOL(posix_acl_valid); + +/* + * Returns 0 if the acl can be exactly represented in the traditional + * file mode permission bits, or else 1. Returns -E... on error. + */ +int +posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p) +{ + const struct posix_acl_entry *pa, *pe; + umode_t mode = 0; + int not_equiv = 0; + + /* + * A null ACL can always be presented as mode bits. + */ + if (!acl) + return 0; + + FOREACH_ACL_ENTRY(pa, acl, pe) { + switch (pa->e_tag) { + case ACL_USER_OBJ: + mode |= (pa->e_perm & S_IRWXO) << 6; + break; + case ACL_GROUP_OBJ: + mode |= (pa->e_perm & S_IRWXO) << 3; + break; + case ACL_OTHER: + mode |= pa->e_perm & S_IRWXO; + break; + case ACL_MASK: + mode = (mode & ~S_IRWXG) | + ((pa->e_perm & S_IRWXO) << 3); + not_equiv = 1; + break; + case ACL_USER: + case ACL_GROUP: + not_equiv = 1; + break; + default: + return -EINVAL; + } + } + if (mode_p) + *mode_p = (*mode_p & ~S_IRWXUGO) | mode; + return not_equiv; +} +EXPORT_SYMBOL(posix_acl_equiv_mode); + +/* + * Create an ACL representing the file mode permission bits of an inode. + */ +struct posix_acl * +posix_acl_from_mode(umode_t mode, gfp_t flags) +{ + struct posix_acl *acl = posix_acl_alloc(3, flags); + if (!acl) + return ERR_PTR(-ENOMEM); + + acl->a_entries[0].e_tag = ACL_USER_OBJ; + acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6; + + acl->a_entries[1].e_tag = ACL_GROUP_OBJ; + acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3; + + acl->a_entries[2].e_tag = ACL_OTHER; + acl->a_entries[2].e_perm = (mode & S_IRWXO); + return acl; +} +EXPORT_SYMBOL(posix_acl_from_mode); + +/* + * Return 0 if current is granted want access to the inode + * by the acl. Returns -E... otherwise. + */ +int +posix_acl_permission(struct user_namespace *mnt_userns, struct inode *inode, + const struct posix_acl *acl, int want) +{ + const struct posix_acl_entry *pa, *pe, *mask_obj; + struct user_namespace *fs_userns = i_user_ns(inode); + int found = 0; + vfsuid_t vfsuid; + vfsgid_t vfsgid; + + want &= MAY_READ | MAY_WRITE | MAY_EXEC; + + FOREACH_ACL_ENTRY(pa, acl, pe) { + switch(pa->e_tag) { + case ACL_USER_OBJ: + /* (May have been checked already) */ + vfsuid = i_uid_into_vfsuid(mnt_userns, inode); + if (vfsuid_eq_kuid(vfsuid, current_fsuid())) + goto check_perm; + break; + case ACL_USER: + vfsuid = make_vfsuid(mnt_userns, fs_userns, + pa->e_uid); + if (vfsuid_eq_kuid(vfsuid, current_fsuid())) + goto mask; + break; + case ACL_GROUP_OBJ: + vfsgid = i_gid_into_vfsgid(mnt_userns, inode); + if (vfsgid_in_group_p(vfsgid)) { + found = 1; + if ((pa->e_perm & want) == want) + goto mask; + } + break; + case ACL_GROUP: + vfsgid = make_vfsgid(mnt_userns, fs_userns, + pa->e_gid); + if (vfsgid_in_group_p(vfsgid)) { + found = 1; + if ((pa->e_perm & want) == want) + goto mask; + } + break; + case ACL_MASK: + break; + case ACL_OTHER: + if (found) + return -EACCES; + else + goto check_perm; + default: + return -EIO; + } + } + return -EIO; + +mask: + for (mask_obj = pa+1; mask_obj != pe; mask_obj++) { + if (mask_obj->e_tag == ACL_MASK) { + if ((pa->e_perm & mask_obj->e_perm & want) == want) + return 0; + return -EACCES; + } + } + +check_perm: + if ((pa->e_perm & want) == want) + return 0; + return -EACCES; +} + +/* + * Modify acl when creating a new inode. The caller must ensure the acl is + * only referenced once. + * + * mode_p initially must contain the mode parameter to the open() / creat() + * system calls. All permissions that are not granted by the acl are removed. + * The permissions in the acl are changed to reflect the mode_p parameter. + */ +static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p) +{ + struct posix_acl_entry *pa, *pe; + struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; + umode_t mode = *mode_p; + int not_equiv = 0; + + /* assert(atomic_read(acl->a_refcount) == 1); */ + + FOREACH_ACL_ENTRY(pa, acl, pe) { + switch(pa->e_tag) { + case ACL_USER_OBJ: + pa->e_perm &= (mode >> 6) | ~S_IRWXO; + mode &= (pa->e_perm << 6) | ~S_IRWXU; + break; + + case ACL_USER: + case ACL_GROUP: + not_equiv = 1; + break; + + case ACL_GROUP_OBJ: + group_obj = pa; + break; + + case ACL_OTHER: + pa->e_perm &= mode | ~S_IRWXO; + mode &= pa->e_perm | ~S_IRWXO; + break; + + case ACL_MASK: + mask_obj = pa; + not_equiv = 1; + break; + + default: + return -EIO; + } + } + + if (mask_obj) { + mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO; + mode &= (mask_obj->e_perm << 3) | ~S_IRWXG; + } else { + if (!group_obj) + return -EIO; + group_obj->e_perm &= (mode >> 3) | ~S_IRWXO; + mode &= (group_obj->e_perm << 3) | ~S_IRWXG; + } + + *mode_p = (*mode_p & ~S_IRWXUGO) | mode; + return not_equiv; +} + +/* + * Modify the ACL for the chmod syscall. + */ +static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode) +{ + struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; + struct posix_acl_entry *pa, *pe; + + /* assert(atomic_read(acl->a_refcount) == 1); */ + + FOREACH_ACL_ENTRY(pa, acl, pe) { + switch(pa->e_tag) { + case ACL_USER_OBJ: + pa->e_perm = (mode & S_IRWXU) >> 6; + break; + + case ACL_USER: + case ACL_GROUP: + break; + + case ACL_GROUP_OBJ: + group_obj = pa; + break; + + case ACL_MASK: + mask_obj = pa; + break; + + case ACL_OTHER: + pa->e_perm = (mode & S_IRWXO); + break; + + default: + return -EIO; + } + } + + if (mask_obj) { + mask_obj->e_perm = (mode & S_IRWXG) >> 3; + } else { + if (!group_obj) + return -EIO; + group_obj->e_perm = (mode & S_IRWXG) >> 3; + } + + return 0; +} + +int +__posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p) +{ + struct posix_acl *clone = posix_acl_clone(*acl, gfp); + int err = -ENOMEM; + if (clone) { + err = posix_acl_create_masq(clone, mode_p); + if (err < 0) { + posix_acl_release(clone); + clone = NULL; + } + } + posix_acl_release(*acl); + *acl = clone; + return err; +} +EXPORT_SYMBOL(__posix_acl_create); + +int +__posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode) +{ + struct posix_acl *clone = posix_acl_clone(*acl, gfp); + int err = -ENOMEM; + if (clone) { + err = __posix_acl_chmod_masq(clone, mode); + if (err) { + posix_acl_release(clone); + clone = NULL; + } + } + posix_acl_release(*acl); + *acl = clone; + return err; +} +EXPORT_SYMBOL(__posix_acl_chmod); + +/** + * posix_acl_chmod - chmod a posix acl + * + * @mnt_userns: user namespace of the mount @inode was found from + * @inode: inode to check permissions on + * @mode: the new mode of @inode + * + * If the inode has been found through an idmapped mount the user namespace of + * the vfsmount must be passed through @mnt_userns. This function will then + * take care to map the inode according to @mnt_userns before checking + * permissions. On non-idmapped mounts or if permission checking is to be + * performed on the raw inode simply passs init_user_ns. + */ +int + posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode, + umode_t mode) +{ + struct posix_acl *acl; + int ret = 0; + + if (!IS_POSIXACL(inode)) + return 0; + if (!inode->i_op->set_acl) + return -EOPNOTSUPP; + + acl = get_acl(inode, ACL_TYPE_ACCESS); + if (IS_ERR_OR_NULL(acl)) { + if (acl == ERR_PTR(-EOPNOTSUPP)) + return 0; + return PTR_ERR(acl); + } + + ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode); + if (ret) + return ret; + ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS); + posix_acl_release(acl); + return ret; +} +EXPORT_SYMBOL(posix_acl_chmod); + +int +posix_acl_create(struct inode *dir, umode_t *mode, + struct posix_acl **default_acl, struct posix_acl **acl) +{ + struct posix_acl *p; + struct posix_acl *clone; + int ret; + + *acl = NULL; + *default_acl = NULL; + + if (S_ISLNK(*mode) || !IS_POSIXACL(dir)) + return 0; + + p = get_acl(dir, ACL_TYPE_DEFAULT); + if (!p || p == ERR_PTR(-EOPNOTSUPP)) { + *mode &= ~current_umask(); + return 0; + } + if (IS_ERR(p)) + return PTR_ERR(p); + + ret = -ENOMEM; + clone = posix_acl_clone(p, GFP_NOFS); + if (!clone) + goto err_release; + + ret = posix_acl_create_masq(clone, mode); + if (ret < 0) + goto err_release_clone; + + if (ret == 0) + posix_acl_release(clone); + else + *acl = clone; + + if (!S_ISDIR(*mode)) + posix_acl_release(p); + else + *default_acl = p; + + return 0; + +err_release_clone: + posix_acl_release(clone); +err_release: + posix_acl_release(p); + return ret; +} +EXPORT_SYMBOL_GPL(posix_acl_create); + +/** + * posix_acl_update_mode - update mode in set_acl + * @mnt_userns: user namespace of the mount @inode was found from + * @inode: target inode + * @mode_p: mode (pointer) for update + * @acl: acl pointer + * + * Update the file mode when setting an ACL: compute the new file permission + * bits based on the ACL. In addition, if the ACL is equivalent to the new + * file mode, set *@acl to NULL to indicate that no ACL should be set. + * + * As with chmod, clear the setgid bit if the caller is not in the owning group + * or capable of CAP_FSETID (see inode_change_ok). + * + * If the inode has been found through an idmapped mount the user namespace of + * the vfsmount must be passed through @mnt_userns. This function will then + * take care to map the inode according to @mnt_userns before checking + * permissions. On non-idmapped mounts or if permission checking is to be + * performed on the raw inode simply passs init_user_ns. + * + * Called from set_acl inode operations. + */ +int posix_acl_update_mode(struct user_namespace *mnt_userns, + struct inode *inode, umode_t *mode_p, + struct posix_acl **acl) +{ + umode_t mode = inode->i_mode; + int error; + + error = posix_acl_equiv_mode(*acl, &mode); + if (error < 0) + return error; + if (error == 0) + *acl = NULL; + if (!vfsgid_in_group_p(i_gid_into_vfsgid(mnt_userns, inode)) && + !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID)) + mode &= ~S_ISGID; + *mode_p = mode; + return 0; +} +EXPORT_SYMBOL(posix_acl_update_mode); + +/* + * Fix up the uids and gids in posix acl extended attributes in place. + */ +static int posix_acl_fix_xattr_common(const void *value, size_t size) +{ + const struct posix_acl_xattr_header *header = value; + int count; + + if (!header) + return -EINVAL; + if (size < sizeof(struct posix_acl_xattr_header)) + return -EINVAL; + if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) + return -EOPNOTSUPP; + + count = posix_acl_xattr_count(size); + if (count < 0) + return -EINVAL; + if (count == 0) + return 0; + + return count; +} + +void posix_acl_getxattr_idmapped_mnt(struct user_namespace *mnt_userns, + const struct inode *inode, + void *value, size_t size) +{ + struct posix_acl_xattr_header *header = value; + struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; + struct user_namespace *fs_userns = i_user_ns(inode); + int count; + vfsuid_t vfsuid; + vfsgid_t vfsgid; + kuid_t uid; + kgid_t gid; + + if (no_idmapping(mnt_userns, i_user_ns(inode))) + return; + + count = posix_acl_fix_xattr_common(value, size); + if (count <= 0) + return; + + for (end = entry + count; entry != end; entry++) { + switch (le16_to_cpu(entry->e_tag)) { + case ACL_USER: + uid = make_kuid(&init_user_ns, le32_to_cpu(entry->e_id)); + vfsuid = make_vfsuid(mnt_userns, fs_userns, uid); + entry->e_id = cpu_to_le32(from_kuid(&init_user_ns, + vfsuid_into_kuid(vfsuid))); + break; + case ACL_GROUP: + gid = make_kgid(&init_user_ns, le32_to_cpu(entry->e_id)); + vfsgid = make_vfsgid(mnt_userns, fs_userns, gid); + entry->e_id = cpu_to_le32(from_kgid(&init_user_ns, + vfsgid_into_kgid(vfsgid))); + break; + default: + break; + } + } +} + +static void posix_acl_fix_xattr_userns( + struct user_namespace *to, struct user_namespace *from, + void *value, size_t size) +{ + struct posix_acl_xattr_header *header = value; + struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; + int count; + kuid_t uid; + kgid_t gid; + + count = posix_acl_fix_xattr_common(value, size); + if (count <= 0) + return; + + for (end = entry + count; entry != end; entry++) { + switch(le16_to_cpu(entry->e_tag)) { + case ACL_USER: + uid = make_kuid(from, le32_to_cpu(entry->e_id)); + entry->e_id = cpu_to_le32(from_kuid(to, uid)); + break; + case ACL_GROUP: + gid = make_kgid(from, le32_to_cpu(entry->e_id)); + entry->e_id = cpu_to_le32(from_kgid(to, gid)); + break; + default: + break; + } + } +} + +void posix_acl_fix_xattr_from_user(void *value, size_t size) +{ + struct user_namespace *user_ns = current_user_ns(); + if (user_ns == &init_user_ns) + return; + posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size); +} + +void posix_acl_fix_xattr_to_user(void *value, size_t size) +{ + struct user_namespace *user_ns = current_user_ns(); + if (user_ns == &init_user_ns) + return; + posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size); +} + +/** + * make_posix_acl - convert POSIX ACLs from uapi to VFS format using the + * provided callbacks to map ACL_{GROUP,USER} entries into the + * appropriate format + * @mnt_userns: the mount's idmapping + * @fs_userns: the filesystem's idmapping + * @value: the uapi representation of POSIX ACLs + * @size: the size of @void + * @uid_cb: callback to use for mapping the uid stored in ACL_USER entries + * @gid_cb: callback to use for mapping the gid stored in ACL_GROUP entries + * + * The make_posix_acl() helper is an abstraction to translate from uapi format + * into the VFS format allowing the caller to specific callbacks to map + * ACL_{GROUP,USER} entries into the expected format. This is used in + * posix_acl_from_xattr() and vfs_set_acl_prepare() and avoids pointless code + * duplication. + * + * Return: Allocated struct posix_acl on success, NULL for a valid header but + * without actual POSIX ACL entries, or ERR_PTR() encoded error code. + */ +static struct posix_acl *make_posix_acl(struct user_namespace *mnt_userns, + struct user_namespace *fs_userns, const void *value, size_t size, + kuid_t (*uid_cb)(struct user_namespace *, struct user_namespace *, + const struct posix_acl_xattr_entry *), + kgid_t (*gid_cb)(struct user_namespace *, struct user_namespace *, + const struct posix_acl_xattr_entry *)) +{ + const struct posix_acl_xattr_header *header = value; + const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end; + int count; + struct posix_acl *acl; + struct posix_acl_entry *acl_e; + + count = posix_acl_fix_xattr_common(value, size); + if (count < 0) + return ERR_PTR(count); + if (count == 0) + return NULL; + + acl = posix_acl_alloc(count, GFP_NOFS); + if (!acl) + return ERR_PTR(-ENOMEM); + acl_e = acl->a_entries; + + for (end = entry + count; entry != end; acl_e++, entry++) { + acl_e->e_tag = le16_to_cpu(entry->e_tag); + acl_e->e_perm = le16_to_cpu(entry->e_perm); + + switch(acl_e->e_tag) { + case ACL_USER_OBJ: + case ACL_GROUP_OBJ: + case ACL_MASK: + case ACL_OTHER: + break; + + case ACL_USER: + acl_e->e_uid = uid_cb(mnt_userns, fs_userns, entry); + if (!uid_valid(acl_e->e_uid)) + goto fail; + break; + case ACL_GROUP: + acl_e->e_gid = gid_cb(mnt_userns, fs_userns, entry); + if (!gid_valid(acl_e->e_gid)) + goto fail; + break; + + default: + goto fail; + } + } + return acl; + +fail: + posix_acl_release(acl); + return ERR_PTR(-EINVAL); +} + +/** + * vfs_set_acl_prepare_kuid - map ACL_USER uid according to mount- and + * filesystem idmapping + * @mnt_userns: the mount's idmapping + * @fs_userns: the filesystem's idmapping + * @e: a ACL_USER entry in POSIX ACL uapi format + * + * The uid stored as ACL_USER entry in @e is a kuid_t stored as a raw {g,u}id + * value. The vfs_set_acl_prepare_kuid() will recover the kuid_t through + * KUIDT_INIT() and then map it according to the idmapped mount. The resulting + * kuid_t is the value which the filesystem can map up into a raw backing store + * id in the filesystem's idmapping. + * + * This is used in vfs_set_acl_prepare() to generate the proper VFS + * representation of POSIX ACLs with ACL_USER entries during setxattr(). + * + * Return: A kuid in @fs_userns for the uid stored in @e. + */ +static inline kuid_t +vfs_set_acl_prepare_kuid(struct user_namespace *mnt_userns, + struct user_namespace *fs_userns, + const struct posix_acl_xattr_entry *e) +{ + kuid_t kuid = KUIDT_INIT(le32_to_cpu(e->e_id)); + return from_vfsuid(mnt_userns, fs_userns, VFSUIDT_INIT(kuid)); +} + +/** + * vfs_set_acl_prepare_kgid - map ACL_GROUP gid according to mount- and + * filesystem idmapping + * @mnt_userns: the mount's idmapping + * @fs_userns: the filesystem's idmapping + * @e: a ACL_GROUP entry in POSIX ACL uapi format + * + * The gid stored as ACL_GROUP entry in @e is a kgid_t stored as a raw {g,u}id + * value. The vfs_set_acl_prepare_kgid() will recover the kgid_t through + * KGIDT_INIT() and then map it according to the idmapped mount. The resulting + * kgid_t is the value which the filesystem can map up into a raw backing store + * id in the filesystem's idmapping. + * + * This is used in vfs_set_acl_prepare() to generate the proper VFS + * representation of POSIX ACLs with ACL_GROUP entries during setxattr(). + * + * Return: A kgid in @fs_userns for the gid stored in @e. + */ +static inline kgid_t +vfs_set_acl_prepare_kgid(struct user_namespace *mnt_userns, + struct user_namespace *fs_userns, + const struct posix_acl_xattr_entry *e) +{ + kgid_t kgid = KGIDT_INIT(le32_to_cpu(e->e_id)); + return from_vfsgid(mnt_userns, fs_userns, VFSGIDT_INIT(kgid)); +} + +/** + * vfs_set_acl_prepare - convert POSIX ACLs from uapi to VFS format taking + * mount and filesystem idmappings into account + * @mnt_userns: the mount's idmapping + * @fs_userns: the filesystem's idmapping + * @value: the uapi representation of POSIX ACLs + * @size: the size of @void + * + * When setting POSIX ACLs with ACL_{GROUP,USER} entries they need to be + * mapped according to the relevant mount- and filesystem idmapping. It is + * important that the ACL_{GROUP,USER} entries in struct posix_acl will be + * mapped into k{g,u}id_t that are supposed to be mapped up in the filesystem + * idmapping. This is crucial since the resulting struct posix_acl might be + * cached filesystem wide. The vfs_set_acl_prepare() function will take care to + * perform all necessary idmappings. + * + * Note, that since basically forever the {g,u}id values encoded as + * ACL_{GROUP,USER} entries in the uapi POSIX ACLs passed via @value contain + * values that have been mapped according to the caller's idmapping. In other + * words, POSIX ACLs passed in uapi format as @value during setxattr() contain + * {g,u}id values in their ACL_{GROUP,USER} entries that should actually have + * been stored as k{g,u}id_t. + * + * This means, vfs_set_acl_prepare() needs to first recover the k{g,u}id_t by + * calling K{G,U}IDT_INIT(). Afterwards they can be interpreted as vfs{g,u}id_t + * through from_vfs{g,u}id() to account for any idmapped mounts. The + * vfs_set_acl_prepare_k{g,u}id() helpers will take care to generate the + * correct k{g,u}id_t. + * + * The filesystem will then receive the POSIX ACLs ready to be cached + * filesystem wide and ready to be written to the backing store taking the + * filesystem's idmapping into account. + * + * Return: Allocated struct posix_acl on success, NULL for a valid header but + * without actual POSIX ACL entries, or ERR_PTR() encoded error code. + */ +struct posix_acl *vfs_set_acl_prepare(struct user_namespace *mnt_userns, + struct user_namespace *fs_userns, + const void *value, size_t size) +{ + return make_posix_acl(mnt_userns, fs_userns, value, size, + vfs_set_acl_prepare_kuid, + vfs_set_acl_prepare_kgid); +} +EXPORT_SYMBOL(vfs_set_acl_prepare); + +/** + * posix_acl_from_xattr_kuid - map ACL_USER uid into filesystem idmapping + * @mnt_userns: unused + * @fs_userns: the filesystem's idmapping + * @e: a ACL_USER entry in POSIX ACL uapi format + * + * Map the uid stored as ACL_USER entry in @e into the filesystem's idmapping. + * This is used in posix_acl_from_xattr() to generate the proper VFS + * representation of POSIX ACLs with ACL_USER entries. + * + * Return: A kuid in @fs_userns for the uid stored in @e. + */ +static inline kuid_t +posix_acl_from_xattr_kuid(struct user_namespace *mnt_userns, + struct user_namespace *fs_userns, + const struct posix_acl_xattr_entry *e) +{ + return make_kuid(fs_userns, le32_to_cpu(e->e_id)); +} + +/** + * posix_acl_from_xattr_kgid - map ACL_GROUP gid into filesystem idmapping + * @mnt_userns: unused + * @fs_userns: the filesystem's idmapping + * @e: a ACL_GROUP entry in POSIX ACL uapi format + * + * Map the gid stored as ACL_GROUP entry in @e into the filesystem's idmapping. + * This is used in posix_acl_from_xattr() to generate the proper VFS + * representation of POSIX ACLs with ACL_GROUP entries. + * + * Return: A kgid in @fs_userns for the gid stored in @e. + */ +static inline kgid_t +posix_acl_from_xattr_kgid(struct user_namespace *mnt_userns, + struct user_namespace *fs_userns, + const struct posix_acl_xattr_entry *e) +{ + return make_kgid(fs_userns, le32_to_cpu(e->e_id)); +} + +/** + * posix_acl_from_xattr - convert POSIX ACLs from backing store to VFS format + * @fs_userns: the filesystem's idmapping + * @value: the uapi representation of POSIX ACLs + * @size: the size of @void + * + * Filesystems that store POSIX ACLs in the unaltered uapi format should use + * posix_acl_from_xattr() when reading them from the backing store and + * converting them into the struct posix_acl VFS format. The helper is + * specifically intended to be called from the ->get_acl() inode operation. + * + * The posix_acl_from_xattr() function will map the raw {g,u}id values stored + * in ACL_{GROUP,USER} entries into the filesystem idmapping in @fs_userns. The + * posix_acl_from_xattr_k{g,u}id() helpers will take care to generate the + * correct k{g,u}id_t. The returned struct posix_acl can be cached. + * + * Note that posix_acl_from_xattr() does not take idmapped mounts into account. + * If it did it calling is from the ->get_acl() inode operation would return + * POSIX ACLs mapped according to an idmapped mount which would mean that the + * value couldn't be cached for the filesystem. Idmapped mounts are taken into + * account on the fly during permission checking or right at the VFS - + * userspace boundary before reporting them to the user. + * + * Return: Allocated struct posix_acl on success, NULL for a valid header but + * without actual POSIX ACL entries, or ERR_PTR() encoded error code. + */ +struct posix_acl * +posix_acl_from_xattr(struct user_namespace *fs_userns, + const void *value, size_t size) +{ + return make_posix_acl(&init_user_ns, fs_userns, value, size, + posix_acl_from_xattr_kuid, + posix_acl_from_xattr_kgid); +} +EXPORT_SYMBOL (posix_acl_from_xattr); + +/* + * Convert from in-memory to extended attribute representation. + */ +int +posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl, + void *buffer, size_t size) +{ + struct posix_acl_xattr_header *ext_acl = buffer; + struct posix_acl_xattr_entry *ext_entry; + int real_size, n; + + real_size = posix_acl_xattr_size(acl->a_count); + if (!buffer) + return real_size; + if (real_size > size) + return -ERANGE; + + ext_entry = (void *)(ext_acl + 1); + ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); + + for (n=0; n < acl->a_count; n++, ext_entry++) { + const struct posix_acl_entry *acl_e = &acl->a_entries[n]; + ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); + ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); + switch(acl_e->e_tag) { + case ACL_USER: + ext_entry->e_id = + cpu_to_le32(from_kuid(user_ns, acl_e->e_uid)); + break; + case ACL_GROUP: + ext_entry->e_id = + cpu_to_le32(from_kgid(user_ns, acl_e->e_gid)); + break; + default: + ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); + break; + } + } + return real_size; +} +EXPORT_SYMBOL (posix_acl_to_xattr); + +static int +posix_acl_xattr_get(const struct xattr_handler *handler, + struct dentry *unused, struct inode *inode, + const char *name, void *value, size_t size) +{ + struct posix_acl *acl; + int error; + + if (!IS_POSIXACL(inode)) + return -EOPNOTSUPP; + if (S_ISLNK(inode->i_mode)) + return -EOPNOTSUPP; + + acl = get_acl(inode, handler->flags); + if (IS_ERR(acl)) + return PTR_ERR(acl); + if (acl == NULL) + return -ENODATA; + + error = posix_acl_to_xattr(&init_user_ns, acl, value, size); + posix_acl_release(acl); + + return error; +} + +int +set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode, + int type, struct posix_acl *acl) +{ + if (!IS_POSIXACL(inode)) + return -EOPNOTSUPP; + if (!inode->i_op->set_acl) + return -EOPNOTSUPP; + + if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) + return acl ? -EACCES : 0; + if (!inode_owner_or_capable(mnt_userns, inode)) + return -EPERM; + + if (acl) { + int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl); + if (ret) + return ret; + } + return inode->i_op->set_acl(mnt_userns, inode, acl, type); +} +EXPORT_SYMBOL(set_posix_acl); + +static int +posix_acl_xattr_set(const struct xattr_handler *handler, + struct user_namespace *mnt_userns, + struct dentry *unused, struct inode *inode, + const char *name, const void *value, size_t size, + int flags) +{ + struct posix_acl *acl = NULL; + int ret; + + if (value) { + /* + * By the time we end up here the {g,u}ids stored in + * ACL_{GROUP,USER} have already been mapped according to the + * caller's idmapping. The vfs_set_acl_prepare() helper will + * recover them and take idmapped mounts into account. The + * filesystem will receive the POSIX ACLs in the correct + * format ready to be cached or written to the backing store + * taking the filesystem idmapping into account. + */ + acl = vfs_set_acl_prepare(mnt_userns, i_user_ns(inode), + value, size); + if (IS_ERR(acl)) + return PTR_ERR(acl); + } + ret = set_posix_acl(mnt_userns, inode, handler->flags, acl); + posix_acl_release(acl); + return ret; +} + +static bool +posix_acl_xattr_list(struct dentry *dentry) +{ + return IS_POSIXACL(d_backing_inode(dentry)); +} + +const struct xattr_handler posix_acl_access_xattr_handler = { + .name = XATTR_NAME_POSIX_ACL_ACCESS, + .flags = ACL_TYPE_ACCESS, + .list = posix_acl_xattr_list, + .get = posix_acl_xattr_get, + .set = posix_acl_xattr_set, +}; +EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler); + +const struct xattr_handler posix_acl_default_xattr_handler = { + .name = XATTR_NAME_POSIX_ACL_DEFAULT, + .flags = ACL_TYPE_DEFAULT, + .list = posix_acl_xattr_list, + .get = posix_acl_xattr_get, + .set = posix_acl_xattr_set, +}; +EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler); + +int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode, + struct posix_acl *acl, int type) +{ + int error; + + if (type == ACL_TYPE_ACCESS) { + error = posix_acl_update_mode(mnt_userns, inode, + &inode->i_mode, &acl); + if (error) + return error; + } + + inode->i_ctime = current_time(inode); + if (IS_I_VERSION(inode)) + inode_inc_iversion(inode); + set_cached_acl(inode, type, acl); + return 0; +} + +int simple_acl_create(struct inode *dir, struct inode *inode) +{ + struct posix_acl *default_acl, *acl; + int error; + + error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); + if (error) + return error; + + set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl); + set_cached_acl(inode, ACL_TYPE_ACCESS, acl); + + if (default_acl) + posix_acl_release(default_acl); + if (acl) + posix_acl_release(acl); + return 0; +} |