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![Ernesto A. Fernández](/assets/img/avatar_default.png)
When changing a file's acl mask, reiserfs_set_acl() will first set the group bits of i_mode to the value of the mask, and only then set the actual extended attribute representing the new acl. If the second part fails (due to lack of space, for example) and the file had no acl attribute to begin with, the system will from now on assume that the mask permission bits are actual group permission bits, potentially granting access to the wrong users. Prevent this by only changing the inode mode after the acl has been set. Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz>
404 lines
9.6 KiB
C
404 lines
9.6 KiB
C
#include <linux/capability.h>
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#include <linux/fs.h>
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#include <linux/posix_acl.h>
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#include "reiserfs.h"
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#include <linux/errno.h>
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#include <linux/pagemap.h>
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#include <linux/xattr.h>
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#include <linux/slab.h>
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#include <linux/posix_acl_xattr.h>
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#include "xattr.h"
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#include "acl.h"
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#include <linux/uaccess.h>
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static int __reiserfs_set_acl(struct reiserfs_transaction_handle *th,
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struct inode *inode, int type,
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struct posix_acl *acl);
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int
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reiserfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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{
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int error, error2;
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struct reiserfs_transaction_handle th;
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size_t jcreate_blocks;
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int size = acl ? posix_acl_xattr_size(acl->a_count) : 0;
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int update_mode = 0;
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umode_t mode = inode->i_mode;
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/*
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* Pessimism: We can't assume that anything from the xattr root up
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* has been created.
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*/
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jcreate_blocks = reiserfs_xattr_jcreate_nblocks(inode) +
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reiserfs_xattr_nblocks(inode, size) * 2;
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reiserfs_write_lock(inode->i_sb);
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error = journal_begin(&th, inode->i_sb, jcreate_blocks);
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reiserfs_write_unlock(inode->i_sb);
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if (error == 0) {
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if (type == ACL_TYPE_ACCESS && acl) {
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error = posix_acl_update_mode(inode, &mode, &acl);
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if (error)
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goto unlock;
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update_mode = 1;
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}
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error = __reiserfs_set_acl(&th, inode, type, acl);
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if (!error && update_mode)
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inode->i_mode = mode;
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unlock:
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reiserfs_write_lock(inode->i_sb);
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error2 = journal_end(&th);
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reiserfs_write_unlock(inode->i_sb);
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if (error2)
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error = error2;
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}
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return error;
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}
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/*
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* Convert from filesystem to in-memory representation.
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*/
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static struct posix_acl *reiserfs_posix_acl_from_disk(const void *value, size_t size)
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{
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const char *end = (char *)value + size;
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int n, count;
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struct posix_acl *acl;
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if (!value)
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return NULL;
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if (size < sizeof(reiserfs_acl_header))
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return ERR_PTR(-EINVAL);
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if (((reiserfs_acl_header *) value)->a_version !=
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cpu_to_le32(REISERFS_ACL_VERSION))
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return ERR_PTR(-EINVAL);
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value = (char *)value + sizeof(reiserfs_acl_header);
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count = reiserfs_acl_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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for (n = 0; n < count; n++) {
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reiserfs_acl_entry *entry = (reiserfs_acl_entry *) value;
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if ((char *)value + sizeof(reiserfs_acl_entry_short) > end)
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goto fail;
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acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
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acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
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switch (acl->a_entries[n].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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value = (char *)value +
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sizeof(reiserfs_acl_entry_short);
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break;
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case ACL_USER:
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value = (char *)value + sizeof(reiserfs_acl_entry);
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if ((char *)value > end)
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goto fail;
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acl->a_entries[n].e_uid =
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make_kuid(&init_user_ns,
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le32_to_cpu(entry->e_id));
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break;
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case ACL_GROUP:
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value = (char *)value + sizeof(reiserfs_acl_entry);
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if ((char *)value > end)
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goto fail;
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acl->a_entries[n].e_gid =
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make_kgid(&init_user_ns,
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le32_to_cpu(entry->e_id));
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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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if (value != end)
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goto fail;
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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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/*
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* Convert from in-memory to filesystem representation.
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*/
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static void *reiserfs_posix_acl_to_disk(const struct posix_acl *acl, size_t * size)
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{
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reiserfs_acl_header *ext_acl;
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char *e;
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int n;
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*size = reiserfs_acl_size(acl->a_count);
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ext_acl = kmalloc(sizeof(reiserfs_acl_header) +
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acl->a_count *
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sizeof(reiserfs_acl_entry),
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GFP_NOFS);
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if (!ext_acl)
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return ERR_PTR(-ENOMEM);
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ext_acl->a_version = cpu_to_le32(REISERFS_ACL_VERSION);
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e = (char *)ext_acl + sizeof(reiserfs_acl_header);
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for (n = 0; n < acl->a_count; n++) {
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const struct posix_acl_entry *acl_e = &acl->a_entries[n];
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reiserfs_acl_entry *entry = (reiserfs_acl_entry *) e;
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entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
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entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
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switch (acl->a_entries[n].e_tag) {
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case ACL_USER:
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entry->e_id = cpu_to_le32(
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from_kuid(&init_user_ns, acl_e->e_uid));
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e += sizeof(reiserfs_acl_entry);
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break;
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case ACL_GROUP:
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entry->e_id = cpu_to_le32(
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from_kgid(&init_user_ns, acl_e->e_gid));
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e += sizeof(reiserfs_acl_entry);
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break;
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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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e += sizeof(reiserfs_acl_entry_short);
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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 (char *)ext_acl;
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fail:
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kfree(ext_acl);
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return ERR_PTR(-EINVAL);
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}
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/*
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* Inode operation get_posix_acl().
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*
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* inode->i_mutex: down
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* BKL held [before 2.5.x]
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*/
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struct posix_acl *reiserfs_get_acl(struct inode *inode, int type)
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{
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char *name, *value;
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struct posix_acl *acl;
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int size;
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int retval;
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switch (type) {
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case ACL_TYPE_ACCESS:
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name = XATTR_NAME_POSIX_ACL_ACCESS;
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break;
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case ACL_TYPE_DEFAULT:
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name = XATTR_NAME_POSIX_ACL_DEFAULT;
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break;
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default:
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BUG();
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}
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size = reiserfs_xattr_get(inode, name, NULL, 0);
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if (size < 0) {
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if (size == -ENODATA || size == -ENOSYS)
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return NULL;
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return ERR_PTR(size);
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}
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value = kmalloc(size, GFP_NOFS);
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if (!value)
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return ERR_PTR(-ENOMEM);
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retval = reiserfs_xattr_get(inode, name, value, size);
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if (retval == -ENODATA || retval == -ENOSYS) {
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/*
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* This shouldn't actually happen as it should have
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* been caught above.. but just in case
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*/
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acl = NULL;
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} else if (retval < 0) {
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acl = ERR_PTR(retval);
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} else {
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acl = reiserfs_posix_acl_from_disk(value, retval);
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}
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kfree(value);
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return acl;
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}
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/*
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* Inode operation set_posix_acl().
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*
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* inode->i_mutex: down
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* BKL held [before 2.5.x]
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*/
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static int
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__reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
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int type, struct posix_acl *acl)
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{
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char *name;
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void *value = NULL;
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size_t size = 0;
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int error;
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switch (type) {
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case ACL_TYPE_ACCESS:
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name = XATTR_NAME_POSIX_ACL_ACCESS;
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break;
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case ACL_TYPE_DEFAULT:
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name = XATTR_NAME_POSIX_ACL_DEFAULT;
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if (!S_ISDIR(inode->i_mode))
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return acl ? -EACCES : 0;
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break;
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default:
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return -EINVAL;
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}
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if (acl) {
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value = reiserfs_posix_acl_to_disk(acl, &size);
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if (IS_ERR(value))
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return (int)PTR_ERR(value);
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}
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error = reiserfs_xattr_set_handle(th, inode, name, value, size, 0);
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/*
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* Ensure that the inode gets dirtied if we're only using
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* the mode bits and an old ACL didn't exist. We don't need
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* to check if the inode is hashed here since we won't get
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* called by reiserfs_inherit_default_acl().
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*/
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if (error == -ENODATA) {
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error = 0;
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if (type == ACL_TYPE_ACCESS) {
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inode->i_ctime = current_time(inode);
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mark_inode_dirty(inode);
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}
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}
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kfree(value);
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if (!error)
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set_cached_acl(inode, type, acl);
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return error;
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}
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/*
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* dir->i_mutex: locked,
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* inode is new and not released into the wild yet
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*/
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int
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reiserfs_inherit_default_acl(struct reiserfs_transaction_handle *th,
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struct inode *dir, struct dentry *dentry,
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struct inode *inode)
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{
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struct posix_acl *default_acl, *acl;
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int err = 0;
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/* ACLs only get applied to files and directories */
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if (S_ISLNK(inode->i_mode))
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return 0;
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/*
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* ACLs can only be used on "new" objects, so if it's an old object
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* there is nothing to inherit from
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*/
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if (get_inode_sd_version(dir) == STAT_DATA_V1)
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goto apply_umask;
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/*
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* Don't apply ACLs to objects in the .reiserfs_priv tree.. This
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* would be useless since permissions are ignored, and a pain because
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* it introduces locking cycles
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*/
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if (IS_PRIVATE(dir)) {
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inode->i_flags |= S_PRIVATE;
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goto apply_umask;
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}
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err = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
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if (err)
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return err;
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if (default_acl) {
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err = __reiserfs_set_acl(th, inode, ACL_TYPE_DEFAULT,
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default_acl);
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posix_acl_release(default_acl);
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}
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if (acl) {
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if (!err)
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err = __reiserfs_set_acl(th, inode, ACL_TYPE_ACCESS,
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acl);
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posix_acl_release(acl);
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}
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return err;
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apply_umask:
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/* no ACL, apply umask */
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inode->i_mode &= ~current_umask();
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return err;
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}
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/* This is used to cache the default acl before a new object is created.
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* The biggest reason for this is to get an idea of how many blocks will
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* actually be required for the create operation if we must inherit an ACL.
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* An ACL write can add up to 3 object creations and an additional file write
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* so we'd prefer not to reserve that many blocks in the journal if we can.
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* It also has the advantage of not loading the ACL with a transaction open,
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* this may seem silly, but if the owner of the directory is doing the
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* creation, the ACL may not be loaded since the permissions wouldn't require
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* it.
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* We return the number of blocks required for the transaction.
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*/
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int reiserfs_cache_default_acl(struct inode *inode)
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{
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struct posix_acl *acl;
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int nblocks = 0;
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if (IS_PRIVATE(inode))
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return 0;
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acl = get_acl(inode, ACL_TYPE_DEFAULT);
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if (acl && !IS_ERR(acl)) {
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int size = reiserfs_acl_size(acl->a_count);
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/* Other xattrs can be created during inode creation. We don't
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* want to claim too many blocks, so we check to see if we
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* we need to create the tree to the xattrs, and then we
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* just want two files. */
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nblocks = reiserfs_xattr_jcreate_nblocks(inode);
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nblocks += JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);
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REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
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/* We need to account for writes + bitmaps for two files */
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nblocks += reiserfs_xattr_nblocks(inode, size) * 4;
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posix_acl_release(acl);
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}
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return nblocks;
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}
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/*
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* Called under i_mutex
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*/
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int reiserfs_acl_chmod(struct inode *inode)
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{
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if (IS_PRIVATE(inode))
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return 0;
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if (get_inode_sd_version(inode) == STAT_DATA_V1 ||
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!reiserfs_posixacl(inode->i_sb))
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return 0;
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return posix_acl_chmod(inode, inode->i_mode);
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}
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