Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c
new file mode 100644
index 0000000..c84d87f
--- /dev/null
+++ b/fs/kernel_read_file.c
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/fs.h>
+#include <linux/fs_struct.h>
+#include <linux/kernel_read_file.h>
+#include <linux/security.h>
+#include <linux/vmalloc.h>
+
+/**
+ * kernel_read_file() - read file contents into a kernel buffer
+ *
+ * @file file to read from
+ * @offset where to start reading from (see below).
+ * @buf pointer to a "void *" buffer for reading into (if
+ * *@buf is NULL, a buffer will be allocated, and
+ * @buf_size will be ignored)
+ * @buf_size size of buf, if already allocated. If @buf not
+ * allocated, this is the largest size to allocate.
+ * @file_size if non-NULL, the full size of @file will be
+ * written here.
+ * @id the kernel_read_file_id identifying the type of
+ * file contents being read (for LSMs to examine)
+ *
+ * @offset must be 0 unless both @buf and @file_size are non-NULL
+ * (i.e. the caller must be expecting to read partial file contents
+ * via an already-allocated @buf, in at most @buf_size chunks, and
+ * will be able to determine when the entire file was read by
+ * checking @file_size). This isn't a recommended way to read a
+ * file, though, since it is possible that the contents might
+ * change between calls to kernel_read_file().
+ *
+ * Returns number of bytes read (no single read will be bigger
+ * than INT_MAX), or negative on error.
+ *
+ */
+int kernel_read_file(struct file *file, loff_t offset, void **buf,
+ size_t buf_size, size_t *file_size,
+ enum kernel_read_file_id id)
+{
+ loff_t i_size, pos;
+ size_t copied;
+ void *allocated = NULL;
+ bool whole_file;
+ int ret;
+
+ if (offset != 0 && (!*buf || !file_size))
+ return -EINVAL;
+
+ if (!S_ISREG(file_inode(file)->i_mode))
+ return -EINVAL;
+
+ ret = deny_write_access(file);
+ if (ret)
+ return ret;
+
+ i_size = i_size_read(file_inode(file));
+ if (i_size <= 0) {
+ ret = -EINVAL;
+ goto out;
+ }
+ /* The file is too big for sane activities. */
+ if (i_size > INT_MAX) {
+ ret = -EFBIG;
+ goto out;
+ }
+ /* The entire file cannot be read in one buffer. */
+ if (!file_size && offset == 0 && i_size > buf_size) {
+ ret = -EFBIG;
+ goto out;
+ }
+
+ whole_file = (offset == 0 && i_size <= buf_size);
+ ret = security_kernel_read_file(file, id, whole_file);
+ if (ret)
+ goto out;
+
+ if (file_size)
+ *file_size = i_size;
+
+ if (!*buf)
+ *buf = allocated = vmalloc(i_size);
+ if (!*buf) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ pos = offset;
+ copied = 0;
+ while (copied < buf_size) {
+ ssize_t bytes;
+ size_t wanted = min_t(size_t, buf_size - copied,
+ i_size - pos);
+
+ bytes = kernel_read(file, *buf + copied, wanted, &pos);
+ if (bytes < 0) {
+ ret = bytes;
+ goto out_free;
+ }
+
+ if (bytes == 0)
+ break;
+ copied += bytes;
+ }
+
+ if (whole_file) {
+ if (pos != i_size) {
+ ret = -EIO;
+ goto out_free;
+ }
+
+ ret = security_kernel_post_read_file(file, *buf, i_size, id);
+ }
+
+out_free:
+ if (ret < 0) {
+ if (allocated) {
+ vfree(*buf);
+ *buf = NULL;
+ }
+ }
+
+out:
+ allow_write_access(file);
+ return ret == 0 ? copied : ret;
+}
+EXPORT_SYMBOL_GPL(kernel_read_file);
+
+int kernel_read_file_from_path(const char *path, loff_t offset, void **buf,
+ size_t buf_size, size_t *file_size,
+ enum kernel_read_file_id id)
+{
+ struct file *file;
+ int ret;
+
+ if (!path || !*path)
+ return -EINVAL;
+
+ file = filp_open(path, O_RDONLY, 0);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ ret = kernel_read_file(file, offset, buf, buf_size, file_size, id);
+ fput(file);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
+
+int kernel_read_file_from_path_initns(const char *path, loff_t offset,
+ void **buf, size_t buf_size,
+ size_t *file_size,
+ enum kernel_read_file_id id)
+{
+ struct file *file;
+ struct path root;
+ int ret;
+
+ if (!path || !*path)
+ return -EINVAL;
+
+ task_lock(&init_task);
+ get_fs_root(init_task.fs, &root);
+ task_unlock(&init_task);
+
+ file = file_open_root(root.dentry, root.mnt, path, O_RDONLY, 0);
+ path_put(&root);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ ret = kernel_read_file(file, offset, buf, buf_size, file_size, id);
+ fput(file);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
+
+int kernel_read_file_from_fd(int fd, loff_t offset, void **buf,
+ size_t buf_size, size_t *file_size,
+ enum kernel_read_file_id id)
+{
+ struct fd f = fdget(fd);
+ int ret = -EBADF;
+
+ if (!f.file || !(f.file->f_mode & FMODE_READ))
+ goto out;
+
+ ret = kernel_read_file(f.file, offset, buf, buf_size, file_size, id);
+out:
+ fdput(f);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);