kernel/linux.git/include/linux/kernel_read_file.h, branch v6.12.80

fs/kernel_read_file: allow to read files up-to ssize_t

2022-06-17T02:58:21+00:00

Patch series "Allow to kexec with initramfs larger than 2G", v2. Currently, the largest initramfs that is supported by kexec_file_load() syscall is 2G. This is because kernel_read_file() returns int, and is limited to INT_MAX or 2G. On the other hand, there are kexec based boot loaders (i.e. u-root), that may need to boot netboot images that might be larger than 2G. The first patch changes the return type from int to ssize_t in kernel_read_file* functions. The second patch increases the maximum initramfs file size to 4G. Tested: verified that can kexec_file_load() works with 4G initramfs on x86_64. This patch (of 2): Currently, the maximum file size that is supported is 2G. This may be too small in some cases. For example, kexec_file_load() system call loads initramfs. In some netboot cases initramfs can be rather large. Allow to use up-to ssize_t bytes. The callers still can limit the maximum file size via buf_size. Link: https://lkml.kernel.org/r/20220527025535.3953665-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20220527025535.3953665-2-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin Cc: Al Viro Cc: Baoquan He Cc: "Eric W. Biederman" Cc: Greg Thelen Cc: Sasha Levin Signed-off-by: Andrew Morton

fs/kernel_file_read: Add "offset" arg for partial reads

2020-10-05T11:37:04+00:00

To perform partial reads, callers of kernel_read_file*() must have a non-NULL file_size argument and a preallocated buffer. The new "offset" argument can then be used to seek to specific locations in the file to fill the buffer to, at most, "buf_size" per call. Where possible, the LSM hooks can report whether a full file has been read or not so that the contents can be reasoned about. Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20201002173828.2099543-14-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

fs/kernel_read_file: Add file_size output argument

2020-10-05T11:37:03+00:00

In preparation for adding partial read support, add an optional output argument to kernel_read_file*() that reports the file size so callers can reason more easily about their reading progress. Signed-off-by: Kees Cook Reviewed-by: Mimi Zohar Reviewed-by: Luis Chamberlain Reviewed-by: James Morris Acked-by: Scott Branden Link: https://lore.kernel.org/r/20201002173828.2099543-8-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

fs/kernel_read_file: Switch buffer size arg to size_t

2020-10-05T11:34:19+00:00

In preparation for further refactoring of kernel_read_file*(), rename the "max_size" argument to the more accurate "buf_size", and correct its type to size_t. Add kerndoc to explain the specifics of how the arguments will be used. Note that with buf_size now size_t, it can no longer be negative (and was never called with a negative value). Adjust callers to use it as a "maximum size" when *buf is NULL. Signed-off-by: Kees Cook Reviewed-by: Mimi Zohar Reviewed-by: Luis Chamberlain Reviewed-by: James Morris Acked-by: Scott Branden Link: https://lore.kernel.org/r/20201002173828.2099543-7-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

fs/kernel_read_file: Remove redundant size argument

2020-10-05T11:34:18+00:00

In preparation for refactoring kernel_read_file*(), remove the redundant "size" argument which is not needed: it can be included in the return code, with callers adjusted. (VFS reads already cannot be larger than INT_MAX.) Signed-off-by: Kees Cook Reviewed-by: Mimi Zohar Reviewed-by: Luis Chamberlain Reviewed-by: James Morris Acked-by: Scott Branden Link: https://lore.kernel.org/r/20201002173828.2099543-6-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

fs/kernel_read_file: Split into separate include file

2020-10-05T11:34:18+00:00

Move kernel_read_file* out of linux/fs.h to its own linux/kernel_read_file.h include file. That header gets pulled in just about everywhere and doesn't really need functions not related to the general fs interface. Suggested-by: Christoph Hellwig Signed-off-by: Scott Branden Signed-off-by: Kees Cook Reviewed-by: Christoph Hellwig Reviewed-by: Mimi Zohar Reviewed-by: Luis Chamberlain Acked-by: Greg Kroah-Hartman Acked-by: James Morris Link: https://lore.kernel.org/r/20200706232309.12010-2-scott.branden@broadcom.com Link: https://lore.kernel.org/r/20201002173828.2099543-4-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman