1 files changed, 523 insertions, 0 deletions

diff --git a/fs/xfs/linux-2.6/xfs_acl.c b/fs/xfs/linux-2.6/xfs_acl.c
new file mode 100644
index 000000000000..1e9d1246eebc
--- /dev/null
+++ b/fs/xfs/linux-2.6/xfs_acl.c
@@ -0,0 +1,523 @@
+/*
+ * Copyright (c) 2008, Christoph Hellwig
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include "xfs.h"
+#include "xfs_acl.h"
+#include "xfs_attr.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_inode.h"
+#include "xfs_vnodeops.h"
+#include <linux/xattr.h>
+#include <linux/posix_acl_xattr.h>
+
+
+#define XFS_ACL_NOT_CACHED      ((void *)-1)
+
+/*
+ * Locking scheme:
+ *  - all ACL updates are protected by inode->i_mutex, which is taken before
+ *    calling into this file.
+ *  - access and updates to the ip->i_acl and ip->i_default_acl pointers are
+ *    protected by inode->i_lock.
+ */
+
+STATIC struct posix_acl *
+xfs_acl_from_disk(struct xfs_acl *aclp)
+{
+        struct posix_acl_entry *acl_e;
+        struct posix_acl *acl;
+        struct xfs_acl_entry *ace;
+        int count, i;
+
+        count = be32_to_cpu(aclp->acl_cnt);
+
+        acl = posix_acl_alloc(count, GFP_KERNEL);
+        if (!acl)
+                return ERR_PTR(-ENOMEM);
+
+        for (i = 0; i < count; i++) {
+                acl_e = &acl->a_entries[i];
+                ace = &aclp->acl_entry[i];
+
+                /*
+                 * The tag is 32 bits on disk and 16 bits in core.
+                 *
+                 * Because every access to it goes through the core
+                 * format first this is not a problem.
+                 */
+                acl_e->e_tag = be32_to_cpu(ace->ae_tag);
+                acl_e->e_perm = be16_to_cpu(ace->ae_perm);
+
+                switch (acl_e->e_tag) {
+                case ACL_USER:
+                case ACL_GROUP:
+                        acl_e->e_id = be32_to_cpu(ace->ae_id);
+                        break;
+                case ACL_USER_OBJ:
+                case ACL_GROUP_OBJ:
+                case ACL_MASK:
+                case ACL_OTHER:
+                        acl_e->e_id = ACL_UNDEFINED_ID;
+                        break;
+                default:
+                        goto fail;
+                }
+        }
+        return acl;
+
+fail:
+        posix_acl_release(acl);
+        return ERR_PTR(-EINVAL);
+}
+
+STATIC void
+xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
+{
+        const struct posix_acl_entry *acl_e;
+        struct xfs_acl_entry *ace;
+        int i;
+
+        aclp->acl_cnt = cpu_to_be32(acl->a_count);
+        for (i = 0; i < acl->a_count; i++) {
+                ace = &aclp->acl_entry[i];
+                acl_e = &acl->a_entries[i];
+
+                ace->ae_tag = cpu_to_be32(acl_e->e_tag);
+                ace->ae_id = cpu_to_be32(acl_e->e_id);
+                ace->ae_perm = cpu_to_be16(acl_e->e_perm);
+        }
+}
+
+/*
+ * Update the cached ACL pointer in the inode.
+ *
+ * Because we don't hold any locks while reading/writing the attribute
+ * from/to disk another thread could have raced and updated the cached
+ * ACL value before us. In that case we release the previous cached value
+ * and update it with our new value.
+ */
+STATIC void
+xfs_update_cached_acl(struct inode *inode, struct posix_acl **p_acl,
+                struct posix_acl *acl)
+{
+        spin_lock(&inode->i_lock);
+        if (*p_acl && *p_acl != XFS_ACL_NOT_CACHED)
+                posix_acl_release(*p_acl);
+        *p_acl = posix_acl_dup(acl);
+        spin_unlock(&inode->i_lock);
+}
+
+struct posix_acl *
+xfs_get_acl(struct inode *inode, int type)
+{
+        struct xfs_inode *ip = XFS_I(inode);
+        struct posix_acl *acl = NULL, **p_acl;
+        struct xfs_acl *xfs_acl;
+        int len = sizeof(struct xfs_acl);
+        char *ea_name;
+        int error;
+
+        switch (type) {
+        case ACL_TYPE_ACCESS:
+                ea_name = SGI_ACL_FILE;
+                p_acl = &ip->i_acl;
+                break;
+        case ACL_TYPE_DEFAULT:
+                ea_name = SGI_ACL_DEFAULT;
+                p_acl = &ip->i_default_acl;
+                break;
+        default:
+                return ERR_PTR(-EINVAL);
+        }
+
+        spin_lock(&inode->i_lock);
+        if (*p_acl != XFS_ACL_NOT_CACHED)
+                acl = posix_acl_dup(*p_acl);
+        spin_unlock(&inode->i_lock);
+
+        /*
+         * If we have a cached ACLs value just return it, not need to
+         * go out to the disk.
+         */
+        if (acl)
+                return acl;
+
+        xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
+        if (!xfs_acl)
+                return ERR_PTR(-ENOMEM);
+
+        error = -xfs_attr_get(ip, ea_name, (char *)xfs_acl, &len, ATTR_ROOT);
+        if (error) {
+                /*
+                 * If the attribute doesn't exist make sure we have a negative
+                 * cache entry, for any other error assume it is transient and
+                 * leave the cache entry as XFS_ACL_NOT_CACHED.
+                 */
+                if (error == -ENOATTR) {
+                        acl = NULL;
+                        goto out_update_cache;
+                }
+                goto out;
+        }
+
+        acl = xfs_acl_from_disk(xfs_acl);
+        if (IS_ERR(acl))
+                goto out;
+
+ out_update_cache:
+        xfs_update_cached_acl(inode, p_acl, acl);
+ out:
+        kfree(xfs_acl);
+        return acl;
+}
+
+STATIC int
+xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
+{
+        struct xfs_inode *ip = XFS_I(inode);
+        struct posix_acl **p_acl;
+        char *ea_name;
+        int error;
+
+        if (S_ISLNK(inode->i_mode))
+                return -EOPNOTSUPP;
+
+        switch (type) {
+        case ACL_TYPE_ACCESS:
+                ea_name = SGI_ACL_FILE;
+                p_acl = &ip->i_acl;
+                break;
+        case ACL_TYPE_DEFAULT:
+                if (!S_ISDIR(inode->i_mode))
+                        return acl ? -EACCES : 0;
+                ea_name = SGI_ACL_DEFAULT;
+                p_acl = &ip->i_default_acl;
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        if (acl) {
+                struct xfs_acl *xfs_acl;
+                int len;
+
+                xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
+                if (!xfs_acl)
+                        return -ENOMEM;
+
+                xfs_acl_to_disk(xfs_acl, acl);
+                len = sizeof(struct xfs_acl) -
+                        (sizeof(struct xfs_acl_entry) *
+                         (XFS_ACL_MAX_ENTRIES - acl->a_count));
+
+                error = -xfs_attr_set(ip, ea_name, (char *)xfs_acl,
+                                len, ATTR_ROOT);
+
+                kfree(xfs_acl);
+        } else {
+                /*
+                 * A NULL ACL argument means we want to remove the ACL.
+                 */
+                error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);
+
+                /*
+                 * If the attribute didn't exist to start with that's fine.
+                 */
+                if (error == -ENOATTR)
+                        error = 0;
+        }
+
+        if (!error)
+                xfs_update_cached_acl(inode, p_acl, acl);
+        return error;
+}
+
+int
+xfs_check_acl(struct inode *inode, int mask)
+{
+        struct xfs_inode *ip = XFS_I(inode);
+        struct posix_acl *acl;
+        int error = -EAGAIN;
+
+        xfs_itrace_entry(ip);
+
+        /*
+         * If there is no attribute fork no ACL exists on this inode and
+         * we can skip the whole exercise.
+         */
+        if (!XFS_IFORK_Q(ip))
+                return -EAGAIN;
+
+        acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
+        if (IS_ERR(acl))
+                return PTR_ERR(acl);
+        if (acl) {
+                error = posix_acl_permission(inode, acl, mask);
+                posix_acl_release(acl);
+        }
+
+        return error;
+}
+
+static int
+xfs_set_mode(struct inode *inode, mode_t mode)
+{
+        int error = 0;
+
+        if (mode != inode->i_mode) {
+                struct iattr iattr;
+
+                iattr.ia_valid = ATTR_MODE;
+                iattr.ia_mode = mode;
+
+                error = -xfs_setattr(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
+        }
+
+        return error;
+}
+
+static int
+xfs_acl_exists(struct inode *inode, char *name)
+{
+        int len = sizeof(struct xfs_acl);
+
+        return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
+                            ATTR_ROOT|ATTR_KERNOVAL) == 0);
+}
+
+int
+posix_acl_access_exists(struct inode *inode)
+{
+        return xfs_acl_exists(inode, SGI_ACL_FILE);
+}
+
+int
+posix_acl_default_exists(struct inode *inode)
+{
+        if (!S_ISDIR(inode->i_mode))
+                return 0;
+        return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
+}
+
+/*
+ * No need for i_mutex because the inode is not yet exposed to the VFS.
+ */
+int
+xfs_inherit_acl(struct inode *inode, struct posix_acl *default_acl)
+{
+        struct posix_acl *clone;
+        mode_t mode;
+        int error = 0, inherit = 0;
+
+        if (S_ISDIR(inode->i_mode)) {
+                error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl);
+                if (error)
+                        return error;
+        }
+
+        clone = posix_acl_clone(default_acl, GFP_KERNEL);
+        if (!clone)
+                return -ENOMEM;
+
+        mode = inode->i_mode;
+        error = posix_acl_create_masq(clone, &mode);
+        if (error < 0)
+                goto out_release_clone;
+
+        /*
+         * If posix_acl_create_masq returns a positive value we need to
+         * inherit a permission that can't be represented using the Unix
+         * mode bits and we actually need to set an ACL.
+         */
+        if (error > 0)
+                inherit = 1;
+
+        error = xfs_set_mode(inode, mode);
+        if (error)
+                goto out_release_clone;
+
+        if (inherit)
+                error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
+
+ out_release_clone:
+        posix_acl_release(clone);
+        return error;
+}
+
+int
+xfs_acl_chmod(struct inode *inode)
+{
+        struct posix_acl *acl, *clone;
+        int error;
+
+        if (S_ISLNK(inode->i_mode))
+                return -EOPNOTSUPP;
+
+        acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
+        if (IS_ERR(acl) || !acl)
+                return PTR_ERR(acl);
+
+        clone = posix_acl_clone(acl, GFP_KERNEL);
+        posix_acl_release(acl);
+        if (!clone)
+                return -ENOMEM;
+
+        error = posix_acl_chmod_masq(clone, inode->i_mode);
+        if (!error)
+                error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
+
+        posix_acl_release(clone);
+        return error;
+}
+
+void
+xfs_inode_init_acls(struct xfs_inode *ip)
+{
+        /*
+         * No need for locking, inode is not live yet.
+         */
+        ip->i_acl = XFS_ACL_NOT_CACHED;
+        ip->i_default_acl = XFS_ACL_NOT_CACHED;
+}
+
+void
+xfs_inode_clear_acls(struct xfs_inode *ip)
+{
+        /*
+         * No need for locking here, the inode is not live anymore
+         * and just about to be freed.
+         */
+        if (ip->i_acl != XFS_ACL_NOT_CACHED)
+                posix_acl_release(ip->i_acl);
+        if (ip->i_default_acl != XFS_ACL_NOT_CACHED)
+                posix_acl_release(ip->i_default_acl);
+}
+
+
+/*
+ * System xattr handlers.
+ *
+ * Currently Posix ACLs are the only system namespace extended attribute
+ * handlers supported by XFS, so we just implement the handlers here.
+ * If we ever support other system extended attributes this will need
+ * some refactoring.
+ */
+
+static int
+xfs_decode_acl(const char *name)
+{
+        if (strcmp(name, "posix_acl_access") == 0)
+                return ACL_TYPE_ACCESS;
+        else if (strcmp(name, "posix_acl_default") == 0)
+                return ACL_TYPE_DEFAULT;
+        return -EINVAL;
+}
+
+static int
+xfs_xattr_system_get(struct inode *inode, const char *name,
+                void *value, size_t size)
+{
+        struct posix_acl *acl;
+        int type, error;
+
+        type = xfs_decode_acl(name);
+        if (type < 0)
+                return type;
+
+        acl = xfs_get_acl(inode, type);
+        if (IS_ERR(acl))
+                return PTR_ERR(acl);
+        if (acl == NULL)
+                return -ENODATA;
+
+        error = posix_acl_to_xattr(acl, value, size);
+        posix_acl_release(acl);
+
+        return error;
+}
+
+static int
+xfs_xattr_system_set(struct inode *inode, const char *name,
+                const void *value, size_t size, int flags)
+{
+        struct posix_acl *acl = NULL;
+        int error = 0, type;
+
+        type = xfs_decode_acl(name);
+        if (type < 0)
+                return type;
+        if (flags & XATTR_CREATE)
+                return -EINVAL;
+        if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
+                return value ? -EACCES : 0;
+        if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
+                return -EPERM;
+
+        if (!value)
+                goto set_acl;
+
+        acl = posix_acl_from_xattr(value, size);
+        if (!acl) {
+                /*
+                 * acl_set_file(3) may request that we set default ACLs with
+                 * zero length -- defend (gracefully) against that here.
+                 */
+                goto out;
+        }
+        if (IS_ERR(acl)) {
+                error = PTR_ERR(acl);
+                goto out;
+        }
+
+        error = posix_acl_valid(acl);
+        if (error)
+                goto out_release;
+
+        error = -EINVAL;
+        if (acl->a_count > XFS_ACL_MAX_ENTRIES)
+                goto out_release;
+
+        if (type == ACL_TYPE_ACCESS) {
+                mode_t mode = inode->i_mode;
+                error = posix_acl_equiv_mode(acl, &mode);
+
+                if (error <= 0) {
+                        posix_acl_release(acl);
+                        acl = NULL;
+
+                        if (error < 0)
+                                return error;
+                }
+
+                error = xfs_set_mode(inode, mode);
+                if (error)
+                        goto out_release;
+        }
+
+ set_acl:
+        error = xfs_set_acl(inode, type, acl);
+ out_release:
+        posix_acl_release(acl);
+ out:
+        return error;
+}
+
+struct xattr_handler xfs_xattr_system_handler = {
+        .prefix = XATTR_SYSTEM_PREFIX,
+        .get    = xfs_xattr_system_get,
+        .set    = xfs_xattr_system_set,
+};