![Eric W. Biederman](/assets/img/avatar_default.png)
- Pass the user namespace the uid and gid values in the xattr are stored in into posix_acl_from_xattr. - Pass the user namespace kuid and kgid values should be converted into when storing uid and gid values in an xattr in posix_acl_to_xattr. - Modify all callers of posix_acl_from_xattr and posix_acl_to_xattr to pass in &init_user_ns. In the short term this change is not strictly needed but it makes the code clearer. In the longer term this change is necessary to be able to mount filesystems outside of the initial user namespace that natively store posix acls in the linux xattr format. Cc: Theodore Tso <tytso@mit.edu> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Jan Kara <jack@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
181 lines
4.3 KiB
C
181 lines
4.3 KiB
C
/*
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* linux/fs/xattr_acl.c
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*
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* Almost all from linux/fs/ext2/acl.c:
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* Copyright (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
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*/
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#include <linux/export.h>
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#include <linux/fs.h>
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#include <linux/posix_acl_xattr.h>
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#include <linux/gfp.h>
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#include <linux/user_namespace.h>
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/*
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* Fix up the uids and gids in posix acl extended attributes in place.
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*/
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static void posix_acl_fix_xattr_userns(
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struct user_namespace *to, struct user_namespace *from,
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void *value, size_t size)
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{
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posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
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posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
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int count;
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kuid_t uid;
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kgid_t gid;
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if (!value)
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return;
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if (size < sizeof(posix_acl_xattr_header))
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return;
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if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
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return;
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count = posix_acl_xattr_count(size);
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if (count < 0)
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return;
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if (count == 0)
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return;
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for (end = entry + count; entry != end; entry++) {
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switch(le16_to_cpu(entry->e_tag)) {
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case ACL_USER:
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uid = make_kuid(from, le32_to_cpu(entry->e_id));
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entry->e_id = cpu_to_le32(from_kuid(to, uid));
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break;
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case ACL_GROUP:
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gid = make_kgid(from, le32_to_cpu(entry->e_id));
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entry->e_id = cpu_to_le32(from_kuid(to, uid));
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break;
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default:
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break;
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}
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}
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}
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void posix_acl_fix_xattr_from_user(void *value, size_t size)
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{
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struct user_namespace *user_ns = current_user_ns();
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if (user_ns == &init_user_ns)
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return;
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posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
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}
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void posix_acl_fix_xattr_to_user(void *value, size_t size)
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{
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struct user_namespace *user_ns = current_user_ns();
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if (user_ns == &init_user_ns)
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return;
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posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
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}
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/*
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* Convert from extended attribute to in-memory representation.
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*/
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struct posix_acl *
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posix_acl_from_xattr(struct user_namespace *user_ns,
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const void *value, size_t size)
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{
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posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
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posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
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int count;
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struct posix_acl *acl;
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struct posix_acl_entry *acl_e;
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if (!value)
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return NULL;
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if (size < sizeof(posix_acl_xattr_header))
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return ERR_PTR(-EINVAL);
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if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
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return ERR_PTR(-EOPNOTSUPP);
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count = posix_acl_xattr_count(size);
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if (count < 0)
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return ERR_PTR(-EINVAL);
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if (count == 0)
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return NULL;
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acl = posix_acl_alloc(count, GFP_NOFS);
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if (!acl)
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return ERR_PTR(-ENOMEM);
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acl_e = acl->a_entries;
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for (end = entry + count; entry != end; acl_e++, entry++) {
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acl_e->e_tag = le16_to_cpu(entry->e_tag);
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acl_e->e_perm = le16_to_cpu(entry->e_perm);
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switch(acl_e->e_tag) {
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case ACL_USER_OBJ:
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case ACL_GROUP_OBJ:
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case ACL_MASK:
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case ACL_OTHER:
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break;
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case ACL_USER:
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acl_e->e_uid =
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make_kuid(user_ns,
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le32_to_cpu(entry->e_id));
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if (!uid_valid(acl_e->e_uid))
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goto fail;
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break;
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case ACL_GROUP:
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acl_e->e_gid =
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make_kgid(user_ns,
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le32_to_cpu(entry->e_id));
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if (!gid_valid(acl_e->e_gid))
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goto fail;
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break;
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default:
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goto fail;
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}
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}
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return acl;
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fail:
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posix_acl_release(acl);
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return ERR_PTR(-EINVAL);
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}
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EXPORT_SYMBOL (posix_acl_from_xattr);
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/*
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* Convert from in-memory to extended attribute representation.
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*/
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int
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posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
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void *buffer, size_t size)
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{
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posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
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posix_acl_xattr_entry *ext_entry = ext_acl->a_entries;
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int real_size, n;
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real_size = posix_acl_xattr_size(acl->a_count);
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if (!buffer)
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return real_size;
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if (real_size > size)
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return -ERANGE;
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ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
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for (n=0; n < acl->a_count; n++, ext_entry++) {
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const struct posix_acl_entry *acl_e = &acl->a_entries[n];
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ext_entry->e_tag = cpu_to_le16(acl_e->e_tag);
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ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
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switch(acl_e->e_tag) {
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case ACL_USER:
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ext_entry->e_id =
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cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
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break;
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case ACL_GROUP:
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ext_entry->e_id =
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cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
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break;
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default:
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ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
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break;
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}
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}
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return real_size;
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}
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EXPORT_SYMBOL (posix_acl_to_xattr);
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