*/
#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/syscalls.h>
#include <linux/namei.h>
#include <linux/file.h>
#include <uapi/linux/mount.h>
+#include "internal.h"
#include "mount.h"
/*
put_fs_context(fc);
return ret;
}
+
+/*
+ * Check the state and apply the configuration. Note that this function is
+ * allowed to 'steal' the value by setting param->xxx to NULL before returning.
+ */
+static int vfs_fsconfig_locked(struct fs_context *fc, int cmd,
+ struct fs_parameter *param)
+{
+ struct super_block *sb;
+ int ret;
+
+ ret = finish_clean_context(fc);
+ if (ret)
+ return ret;
+ switch (cmd) {
+ case FSCONFIG_CMD_CREATE:
+ if (fc->phase != FS_CONTEXT_CREATE_PARAMS)
+ return -EBUSY;
+ fc->phase = FS_CONTEXT_CREATING;
+ ret = vfs_get_tree(fc);
+ if (ret)
+ break;
+ sb = fc->root->d_sb;
+ ret = security_sb_kern_mount(sb);
+ if (unlikely(ret)) {
+ fc_drop_locked(fc);
+ break;
+ }
+ up_write(&sb->s_umount);
+ fc->phase = FS_CONTEXT_AWAITING_MOUNT;
+ return 0;
+ case FSCONFIG_CMD_RECONFIGURE:
+ if (fc->phase != FS_CONTEXT_RECONF_PARAMS)
+ return -EBUSY;
+ fc->phase = FS_CONTEXT_RECONFIGURING;
+ sb = fc->root->d_sb;
+ if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) {
+ ret = -EPERM;
+ break;
+ }
+ down_write(&sb->s_umount);
+ ret = reconfigure_super(fc);
+ up_write(&sb->s_umount);
+ if (ret)
+ break;
+ vfs_clean_context(fc);
+ return 0;
+ default:
+ if (fc->phase != FS_CONTEXT_CREATE_PARAMS &&
+ fc->phase != FS_CONTEXT_RECONF_PARAMS)
+ return -EBUSY;
+
+ return vfs_parse_fs_param(fc, param);
+ }
+ fc->phase = FS_CONTEXT_FAILED;
+ return ret;
+}
+
+/**
+ * sys_fsconfig - Set parameters and trigger actions on a context
+ * @fd: The filesystem context to act upon
+ * @cmd: The action to take
+ * @_key: Where appropriate, the parameter key to set
+ * @_value: Where appropriate, the parameter value to set
+ * @aux: Additional information for the value
+ *
+ * This system call is used to set parameters on a context, including
+ * superblock settings, data source and security labelling.
+ *
+ * Actions include triggering the creation of a superblock and the
+ * reconfiguration of the superblock attached to the specified context.
+ *
+ * When setting a parameter, @cmd indicates the type of value being proposed
+ * and @_key indicates the parameter to be altered.
+ *
+ * @_value and @aux are used to specify the value, should a value be required:
+ *
+ * (*) fsconfig_set_flag: No value is specified. The parameter must be boolean
+ * in nature. The key may be prefixed with "no" to invert the
+ * setting. @_value must be NULL and @aux must be 0.
+ *
+ * (*) fsconfig_set_string: A string value is specified. The parameter can be
+ * expecting boolean, integer, string or take a path. A conversion to an
+ * appropriate type will be attempted (which may include looking up as a
+ * path). @_value points to a NUL-terminated string and @aux must be 0.
+ *
+ * (*) fsconfig_set_binary: A binary blob is specified. @_value points to the
+ * blob and @aux indicates its size. The parameter must be expecting a
+ * blob.
+ *
+ * (*) fsconfig_set_path: A non-empty path is specified. The parameter must be
+ * expecting a path object. @_value points to a NUL-terminated string that
+ * is the path and @aux is a file descriptor at which to start a relative
+ * lookup or AT_FDCWD.
+ *
+ * (*) fsconfig_set_path_empty: As fsconfig_set_path, but with AT_EMPTY_PATH
+ * implied.
+ *
+ * (*) fsconfig_set_fd: An open file descriptor is specified. @_value must be
+ * NULL and @aux indicates the file descriptor.
+ */
+SYSCALL_DEFINE5(fsconfig,
+ int, fd,
+ unsigned int, cmd,
+ const char __user *, _key,
+ const void __user *, _value,
+ int, aux)
+{
+ struct fs_context *fc;
+ struct fd f;
+ int ret;
+
+ struct fs_parameter param = {
+ .type = fs_value_is_undefined,
+ };
+
+ if (fd < 0)
+ return -EINVAL;
+
+ switch (cmd) {
+ case FSCONFIG_SET_FLAG:
+ if (!_key || _value || aux)
+ return -EINVAL;
+ break;
+ case FSCONFIG_SET_STRING:
+ if (!_key || !_value || aux)
+ return -EINVAL;
+ break;
+ case FSCONFIG_SET_BINARY:
+ if (!_key || !_value || aux <= 0 || aux > 1024 * 1024)
+ return -EINVAL;
+ break;
+ case FSCONFIG_SET_PATH:
+ case FSCONFIG_SET_PATH_EMPTY:
+ if (!_key || !_value || (aux != AT_FDCWD && aux < 0))
+ return -EINVAL;
+ break;
+ case FSCONFIG_SET_FD:
+ if (!_key || _value || aux < 0)
+ return -EINVAL;
+ break;
+ case FSCONFIG_CMD_CREATE:
+ case FSCONFIG_CMD_RECONFIGURE:
+ if (_key || _value || aux)
+ return -EINVAL;
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ f = fdget(fd);
+ if (!f.file)
+ return -EBADF;
+ ret = -EINVAL;
+ if (f.file->f_op != &fscontext_fops)
+ goto out_f;
+
+ fc = f.file->private_data;
+ if (fc->ops == &legacy_fs_context_ops) {
+ switch (cmd) {
+ case FSCONFIG_SET_BINARY:
+ case FSCONFIG_SET_PATH:
+ case FSCONFIG_SET_PATH_EMPTY:
+ case FSCONFIG_SET_FD:
+ ret = -EOPNOTSUPP;
+ goto out_f;
+ }
+ }
+
+ if (_key) {
+ param.key = strndup_user(_key, 256);
+ if (IS_ERR(param.key)) {
+ ret = PTR_ERR(param.key);
+ goto out_f;
+ }
+ }
+
+ switch (cmd) {
+ case FSCONFIG_SET_FLAG:
+ param.type = fs_value_is_flag;
+ break;
+ case FSCONFIG_SET_STRING:
+ param.type = fs_value_is_string;
+ param.string = strndup_user(_value, 256);
+ if (IS_ERR(param.string)) {
+ ret = PTR_ERR(param.string);
+ goto out_key;
+ }
+ param.size = strlen(param.string);
+ break;
+ case FSCONFIG_SET_BINARY:
+ param.type = fs_value_is_blob;
+ param.size = aux;
+ param.blob = memdup_user_nul(_value, aux);
+ if (IS_ERR(param.blob)) {
+ ret = PTR_ERR(param.blob);
+ goto out_key;
+ }
+ break;
+ case FSCONFIG_SET_PATH:
+ param.type = fs_value_is_filename;
+ param.name = getname_flags(_value, 0, NULL);
+ if (IS_ERR(param.name)) {
+ ret = PTR_ERR(param.name);
+ goto out_key;
+ }
+ param.dirfd = aux;
+ param.size = strlen(param.name->name);
+ break;
+ case FSCONFIG_SET_PATH_EMPTY:
+ param.type = fs_value_is_filename_empty;
+ param.name = getname_flags(_value, LOOKUP_EMPTY, NULL);
+ if (IS_ERR(param.name)) {
+ ret = PTR_ERR(param.name);
+ goto out_key;
+ }
+ param.dirfd = aux;
+ param.size = strlen(param.name->name);
+ break;
+ case FSCONFIG_SET_FD:
+ param.type = fs_value_is_file;
+ ret = -EBADF;
+ param.file = fget(aux);
+ if (!param.file)
+ goto out_key;
+ break;
+ default:
+ break;
+ }
+
+ ret = mutex_lock_interruptible(&fc->uapi_mutex);
+ if (ret == 0) {
+ ret = vfs_fsconfig_locked(fc, cmd, ¶m);
+ mutex_unlock(&fc->uapi_mutex);
+ }
+
+ /* Clean up the our record of any value that we obtained from
+ * userspace. Note that the value may have been stolen by the LSM or
+ * filesystem, in which case the value pointer will have been cleared.
+ */
+ switch (cmd) {
+ case FSCONFIG_SET_STRING:
+ case FSCONFIG_SET_BINARY:
+ kfree(param.string);
+ break;
+ case FSCONFIG_SET_PATH:
+ case FSCONFIG_SET_PATH_EMPTY:
+ if (param.name)
+ putname(param.name);
+ break;
+ case FSCONFIG_SET_FD:
+ if (param.file)
+ fput(param.file);
+ break;
+ default:
+ break;
+ }
+out_key:
+ kfree(param.key);
+out_f:
+ fdput(f);
+ return ret;
+}
projects / linux-2.6-block.git / commitdiff