Something went wrong. Try again.
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Something went wrong. Try again.
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186// 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 SSIZE_MAX), or negative on error. * */ssize_t 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; ssize_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 > SSIZE_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);
ssize_t 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; ssize_t 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);
ssize_t 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; ssize_t 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, 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);
ssize_t 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){ CLASS(fd, f)(fd);
if (fd_empty(f) || !(fd_file(f)->f_mode & FMODE_READ)) return -EBADF;
return kernel_read_file(fd_file(f), offset, buf, buf_size, file_size, id);}EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);