xattr_acl.c

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#include <linux/capability.h>
#include <linux/fs.h>
#include <linux/posix_acl.h>
#include "reiserfs.h"
#include <linux/errno.h>
#include <linux/pagemap.h>
#include <linux/xattr.h>
#include <linux/slab.h>
#include <linux/posix_acl_xattr.h>
#include "xattr.h"
#include "acl.h"
#include <asm/uaccess.h>

static int reiserfs_set_acl(struct reiserfs_transaction_handle *th,
                struct inode *inode, int type,
                struct posix_acl *acl);

static int
posix_acl_set(struct dentry *dentry, const char *name, const void *value,
        size_t size, int flags, int type)
{
    struct inode *inode = dentry->d_inode;
    struct posix_acl *acl;
    int error, error2;
    struct reiserfs_transaction_handle th;
    size_t jcreate_blocks;
    if (!reiserfs_posixacl(inode->i_sb))
        return -EOPNOTSUPP;
    if (!inode_owner_or_capable(inode))
        return -EPERM;

    if (value) {
        acl = posix_acl_from_xattr(&init_user_ns, value, size);
        if (IS_ERR(acl)) {
            return PTR_ERR(acl);
        } else if (acl) {
            error = posix_acl_valid(acl);
            if (error)
                goto release_and_out;
        }
    } else
        acl = NULL;

    /* Pessimism: We can't assume that anything from the xattr root up
     * has been created. */

    jcreate_blocks = reiserfs_xattr_jcreate_nblocks(inode) +
             reiserfs_xattr_nblocks(inode, size) * 2;

    reiserfs_write_lock(inode->i_sb);
    error = journal_begin(&th, inode->i_sb, jcreate_blocks);
    if (error == 0) {
        error = reiserfs_set_acl(&th, inode, type, acl);
        error2 = journal_end(&th, inode->i_sb, jcreate_blocks);
        if (error2)
            error = error2;
    }
    reiserfs_write_unlock(inode->i_sb);

      release_and_out:
    posix_acl_release(acl);
    return error;
}

static int
posix_acl_get(struct dentry *dentry, const char *name, void *buffer,
        size_t size, int type)
{
    struct posix_acl *acl;
    int error;

    if (!reiserfs_posixacl(dentry->d_sb))
        return -EOPNOTSUPP;

    acl = reiserfs_get_acl(dentry->d_inode, type);
    if (IS_ERR(acl))
        return PTR_ERR(acl);
    if (acl == NULL)
        return -ENODATA;
    error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
    posix_acl_release(acl);

    return error;
}

/*
 * Convert from filesystem to in-memory representation.
 */
static struct posix_acl *posix_acl_from_disk(const void *value, size_t size)
{
    const char *end = (char *)value + size;
    int n, count;
    struct posix_acl *acl;

    if (!value)
        return NULL;
    if (size < sizeof(reiserfs_acl_header))
        return ERR_PTR(-EINVAL);
    if (((reiserfs_acl_header *) value)->a_version !=
        cpu_to_le32(REISERFS_ACL_VERSION))
        return ERR_PTR(-EINVAL);
    value = (char *)value + sizeof(reiserfs_acl_header);
    count = reiserfs_acl_count(size);
    if (count < 0)
        return ERR_PTR(-EINVAL);
    if (count == 0)
        return NULL;
    acl = posix_acl_alloc(count, GFP_NOFS);
    if (!acl)
        return ERR_PTR(-ENOMEM);
    for (n = 0; n < count; n++) {
        reiserfs_acl_entry *entry = (reiserfs_acl_entry *) value;
        if ((char *)value + sizeof(reiserfs_acl_entry_short) > end)
            goto fail;
        acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
        acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
        switch (acl->a_entries[n].e_tag) {
        case ACL_USER_OBJ:
        case ACL_GROUP_OBJ:
        case ACL_MASK:
        case ACL_OTHER:
            value = (char *)value +
                sizeof(reiserfs_acl_entry_short);
            break;

        case ACL_USER:
            value = (char *)value + sizeof(reiserfs_acl_entry);
            if ((char *)value > end)
                goto fail;
            acl->a_entries[n].e_uid = 
                make_kuid(&init_user_ns,
                      le32_to_cpu(entry->e_id));
            break;
        case ACL_GROUP:
            value = (char *)value + sizeof(reiserfs_acl_entry);
            if ((char *)value > end)
                goto fail;
            acl->a_entries[n].e_gid =
                make_kgid(&init_user_ns,
                      le32_to_cpu(entry->e_id));
            break;

        default:
            goto fail;
        }
    }
    if (value != end)
        goto fail;
    return acl;

      fail:
    posix_acl_release(acl);
    return ERR_PTR(-EINVAL);
}

/*
 * Convert from in-memory to filesystem representation.
 */
static void *posix_acl_to_disk(const struct posix_acl *acl, size_t * size)
{
    reiserfs_acl_header *ext_acl;
    char *e;
    int n;

    *size = reiserfs_acl_size(acl->a_count);
    ext_acl = kmalloc(sizeof(reiserfs_acl_header) +
                          acl->a_count *
                          sizeof(reiserfs_acl_entry),
                          GFP_NOFS);
    if (!ext_acl)
        return ERR_PTR(-ENOMEM);
    ext_acl->a_version = cpu_to_le32(REISERFS_ACL_VERSION);
    e = (char *)ext_acl + sizeof(reiserfs_acl_header);
    for (n = 0; n < acl->a_count; n++) {
        const struct posix_acl_entry *acl_e = &acl->a_entries[n];
        reiserfs_acl_entry *entry = (reiserfs_acl_entry *) e;
        entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
        entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
        switch (acl->a_entries[n].e_tag) {
        case ACL_USER:
            entry->e_id = cpu_to_le32(
                from_kuid(&init_user_ns, acl_e->e_uid));
            e += sizeof(reiserfs_acl_entry);
            break;
        case ACL_GROUP:
            entry->e_id = cpu_to_le32(
                from_kgid(&init_user_ns, acl_e->e_gid));
            e += sizeof(reiserfs_acl_entry);
            break;

        case ACL_USER_OBJ:
        case ACL_GROUP_OBJ:
        case ACL_MASK:
        case ACL_OTHER:
            e += sizeof(reiserfs_acl_entry_short);
            break;

        default:
            goto fail;
        }
    }
    return (char *)ext_acl;

      fail:
    kfree(ext_acl);
    return ERR_PTR(-EINVAL);
}

/*
 * Inode operation get_posix_acl().
 *
 * inode->i_mutex: down
 * BKL held [before 2.5.x]
 */
struct posix_acl *reiserfs_get_acl(struct inode *inode, int type)
{
    char *name, *value;
    struct posix_acl *acl;
    int size;
    int retval;

    acl = get_cached_acl(inode, type);
    if (acl != ACL_NOT_CACHED)
        return acl;

    switch (type) {
    case ACL_TYPE_ACCESS:
        name = POSIX_ACL_XATTR_ACCESS;
        break;
    case ACL_TYPE_DEFAULT:
        name = POSIX_ACL_XATTR_DEFAULT;
        break;
    default:
        BUG();
    }

    size = reiserfs_xattr_get(inode, name, NULL, 0);
    if (size < 0) {
        if (size == -ENODATA || size == -ENOSYS) {
            set_cached_acl(inode, type, NULL);
            return NULL;
        }
        return ERR_PTR(size);
    }

    value = kmalloc(size, GFP_NOFS);
    if (!value)
        return ERR_PTR(-ENOMEM);

    retval = reiserfs_xattr_get(inode, name, value, size);
    if (retval == -ENODATA || retval == -ENOSYS) {
        /* This shouldn't actually happen as it should have
           been caught above.. but just in case */
        acl = NULL;
    } else if (retval < 0) {
        acl = ERR_PTR(retval);
    } else {
        acl = posix_acl_from_disk(value, retval);
    }
    if (!IS_ERR(acl))
        set_cached_acl(inode, type, acl);

    kfree(value);
    return acl;
}

/*
 * Inode operation set_posix_acl().
 *
 * inode->i_mutex: down
 * BKL held [before 2.5.x]
 */
static int
reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
         int type, struct posix_acl *acl)
{
    char *name;
    void *value = NULL;
    size_t size = 0;
    int error;

    if (S_ISLNK(inode->i_mode))
        return -EOPNOTSUPP;

    switch (type) {
    case ACL_TYPE_ACCESS:
        name = POSIX_ACL_XATTR_ACCESS;
        if (acl) {
            error = posix_acl_equiv_mode(acl, &inode->i_mode);
            if (error < 0)
                return error;
            else {
                if (error == 0)
                    acl = NULL;
            }
        }
        break;
    case ACL_TYPE_DEFAULT:
        name = POSIX_ACL_XATTR_DEFAULT;
        if (!S_ISDIR(inode->i_mode))
            return acl ? -EACCES : 0;
        break;
    default:
        return -EINVAL;
    }

    if (acl) {
        value = posix_acl_to_disk(acl, &size);
        if (IS_ERR(value))
            return (int)PTR_ERR(value);
    }

    error = reiserfs_xattr_set_handle(th, inode, name, value, size, 0);

    /*
     * Ensure that the inode gets dirtied if we're only using
     * the mode bits and an old ACL didn't exist. We don't need
     * to check if the inode is hashed here since we won't get
     * called by reiserfs_inherit_default_acl().
     */
    if (error == -ENODATA) {
        error = 0;
        if (type == ACL_TYPE_ACCESS) {
            inode->i_ctime = CURRENT_TIME_SEC;
            mark_inode_dirty(inode);
        }
    }

    kfree(value);

    if (!error)
        set_cached_acl(inode, type, acl);

    return error;
}

/* dir->i_mutex: locked,
 * inode is new and not released into the wild yet */
int
reiserfs_inherit_default_acl(struct reiserfs_transaction_handle *th,
                 struct inode *dir, struct dentry *dentry,
                 struct inode *inode)
{
    struct posix_acl *acl;
    int err = 0;

    /* ACLs only get applied to files and directories */
    if (S_ISLNK(inode->i_mode))
        return 0;

    /* ACLs can only be used on "new" objects, so if it's an old object
     * there is nothing to inherit from */
    if (get_inode_sd_version(dir) == STAT_DATA_V1)
        goto apply_umask;

    /* Don't apply ACLs to objects in the .reiserfs_priv tree.. This
     * would be useless since permissions are ignored, and a pain because
     * it introduces locking cycles */
    if (IS_PRIVATE(dir)) {
        inode->i_flags |= S_PRIVATE;
        goto apply_umask;
    }

    acl = reiserfs_get_acl(dir, ACL_TYPE_DEFAULT);
    if (IS_ERR(acl))
        return PTR_ERR(acl);

    if (acl) {
        /* Copy the default ACL to the default ACL of a new directory */
        if (S_ISDIR(inode->i_mode)) {
            err = reiserfs_set_acl(th, inode, ACL_TYPE_DEFAULT,
                           acl);
            if (err)
                goto cleanup;
        }

        /* Now we reconcile the new ACL and the mode,
           potentially modifying both */
        err = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
        if (err < 0)
            return err;

        /* If we need an ACL.. */
        if (err > 0)
            err = reiserfs_set_acl(th, inode, ACL_TYPE_ACCESS, acl);
          cleanup:
        posix_acl_release(acl);
    } else {
          apply_umask:
        /* no ACL, apply umask */
        inode->i_mode &= ~current_umask();
    }

    return err;
}

/* This is used to cache the default acl before a new object is created.
 * The biggest reason for this is to get an idea of how many blocks will
 * actually be required for the create operation if we must inherit an ACL.
 * An ACL write can add up to 3 object creations and an additional file write
 * so we'd prefer not to reserve that many blocks in the journal if we can.
 * It also has the advantage of not loading the ACL with a transaction open,
 * this may seem silly, but if the owner of the directory is doing the
 * creation, the ACL may not be loaded since the permissions wouldn't require
 * it.
 * We return the number of blocks required for the transaction.
 */
int reiserfs_cache_default_acl(struct inode *inode)
{
    struct posix_acl *acl;
    int nblocks = 0;

    if (IS_PRIVATE(inode))
        return 0;

    acl = reiserfs_get_acl(inode, ACL_TYPE_DEFAULT);

    if (acl && !IS_ERR(acl)) {
        int size = reiserfs_acl_size(acl->a_count);

        /* Other xattrs can be created during inode creation. We don't
         * want to claim too many blocks, so we check to see if we
         * we need to create the tree to the xattrs, and then we
         * just want two files. */
        nblocks = reiserfs_xattr_jcreate_nblocks(inode);
        nblocks += JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);

        REISERFS_I(inode)->i_flags |= i_has_xattr_dir;

        /* We need to account for writes + bitmaps for two files */
        nblocks += reiserfs_xattr_nblocks(inode, size) * 4;
        posix_acl_release(acl);
    }

    return nblocks;
}

int reiserfs_acl_chmod(struct inode *inode)
{
    struct reiserfs_transaction_handle th;
    struct posix_acl *acl;
    size_t size;
    int depth;
    int error;

    if (S_ISLNK(inode->i_mode))
        return -EOPNOTSUPP;

    if (get_inode_sd_version(inode) == STAT_DATA_V1 ||
        !reiserfs_posixacl(inode->i_sb)) {
        return 0;
    }

    reiserfs_write_unlock(inode->i_sb);
    acl = reiserfs_get_acl(inode, ACL_TYPE_ACCESS);
    reiserfs_write_lock(inode->i_sb);
    if (!acl)
        return 0;
    if (IS_ERR(acl))
        return PTR_ERR(acl);
    error = posix_acl_chmod(&acl, GFP_NOFS, inode->i_mode);
    if (error)
        return error;

    size = reiserfs_xattr_nblocks(inode, reiserfs_acl_size(acl->a_count));
    depth = reiserfs_write_lock_once(inode->i_sb);
    error = journal_begin(&th, inode->i_sb, size * 2);
    if (!error) {
        int error2;
        error = reiserfs_set_acl(&th, inode, ACL_TYPE_ACCESS, acl);
        error2 = journal_end(&th, inode->i_sb, size * 2);
        if (error2)
            error = error2;
    }
    reiserfs_write_unlock_once(inode->i_sb, depth);
    posix_acl_release(acl);
    return error;
}

static size_t posix_acl_access_list(struct dentry *dentry, char *list,
                    size_t list_size, const char *name,
                    size_t name_len, int type)
{
    const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
    if (!reiserfs_posixacl(dentry->d_sb))
        return 0;
    if (list && size <= list_size)
        memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
    return size;
}

const struct xattr_handler reiserfs_posix_acl_access_handler = {
    .prefix = POSIX_ACL_XATTR_ACCESS,
    .flags = ACL_TYPE_ACCESS,
    .get = posix_acl_get,
    .set = posix_acl_set,
    .list = posix_acl_access_list,
};

static size_t posix_acl_default_list(struct dentry *dentry, char *list,
                     size_t list_size, const char *name,
                     size_t name_len, int type)
{
    const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
    if (!reiserfs_posixacl(dentry->d_sb))
        return 0;
    if (list && size <= list_size)
        memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
    return size;
}

const struct xattr_handler reiserfs_posix_acl_default_handler = {
    .prefix = POSIX_ACL_XATTR_DEFAULT,
    .flags = ACL_TYPE_DEFAULT,
    .get = posix_acl_get,
    .set = posix_acl_set,
    .list = posix_acl_default_list,
};