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efi/libstub: Move file I/O support code into separate file
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Split off the file I/O support code into a separate source file so
it ends up in a separate object file in the static library, allowing
the linker to omit it if the routines are not used.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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Ard Biesheuvel committed Feb 23, 2020
1 parent b871745 commit 5193a33
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Showing 4 changed files with 311 additions and 289 deletions.
2 changes: 1 addition & 1 deletion drivers/firmware/efi/libstub/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ OBJECT_FILES_NON_STANDARD := y
KCOV_INSTRUMENT := n

lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
mem.o random.o randomalloc.o pci.o
file.o mem.o random.o randomalloc.o pci.o

# include the stub's generic dependencies from lib/ when building for ARM/arm64
arm-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c
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294 changes: 6 additions & 288 deletions drivers/firmware/efi/libstub/efi-stub-helper.c
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Original file line number Diff line number Diff line change
Expand Up @@ -12,30 +12,18 @@

#include "efistub.h"

/*
* Some firmware implementations have problems reading files in one go.
* A read chunk size of 1MB seems to work for most platforms.
*
* Unfortunately, reading files in chunks triggers *other* bugs on some
* platforms, so we provide a way to disable this workaround, which can
* be done by passing "efi=nochunk" on the EFI boot stub command line.
*
* If you experience issues with initrd images being corrupt it's worth
* trying efi=nochunk, but chunking is enabled by default because there
* are far more machines that require the workaround than those that
* break with it enabled.
*/
#define EFI_READ_CHUNK_SIZE (1024 * 1024)

static unsigned long efi_chunk_size = EFI_READ_CHUNK_SIZE;

static bool __efistub_global efi_nochunk;
static bool __efistub_global efi_nokaslr;
static bool __efistub_global efi_quiet;
static bool __efistub_global efi_novamap;
static bool __efistub_global efi_nosoftreserve;
static bool __efistub_global efi_disable_pci_dma =
IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA);

bool __pure nochunk(void)
{
return efi_nochunk;
}
bool __pure nokaslr(void)
{
return efi_nokaslr;
Expand All @@ -53,11 +41,6 @@ bool __pure __efi_soft_reserve_enabled(void)
return !efi_nosoftreserve;
}

struct file_info {
efi_file_protocol_t *handle;
u64 size;
};

void efi_printk(char *str)
{
char *s8;
Expand All @@ -75,90 +58,6 @@ void efi_printk(char *str)
}
}

static efi_status_t efi_file_size(void *__fh, efi_char16_t *filename_16,
void **handle, u64 *file_sz)
{
efi_file_protocol_t *h, *fh = __fh;
efi_file_info_t *info;
efi_status_t status;
efi_guid_t info_guid = EFI_FILE_INFO_ID;
unsigned long info_sz;

status = fh->open(fh, &h, filename_16, EFI_FILE_MODE_READ, 0);
if (status != EFI_SUCCESS) {
efi_printk("Failed to open file: ");
efi_char16_printk(filename_16);
efi_printk("\n");
return status;
}

*handle = h;

info_sz = 0;
status = h->get_info(h, &info_guid, &info_sz, NULL);
if (status != EFI_BUFFER_TOO_SMALL) {
efi_printk("Failed to get file info size\n");
return status;
}

grow:
status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, info_sz,
(void **)&info);
if (status != EFI_SUCCESS) {
efi_printk("Failed to alloc mem for file info\n");
return status;
}

status = h->get_info(h, &info_guid, &info_sz, info);
if (status == EFI_BUFFER_TOO_SMALL) {
efi_bs_call(free_pool, info);
goto grow;
}

*file_sz = info->file_size;
efi_bs_call(free_pool, info);

if (status != EFI_SUCCESS)
efi_printk("Failed to get initrd info\n");

return status;
}

static efi_status_t efi_file_read(efi_file_protocol_t *handle,
unsigned long *size, void *addr)
{
return handle->read(handle, size, addr);
}

static efi_status_t efi_file_close(efi_file_protocol_t *handle)
{
return handle->close(handle);
}

static efi_status_t efi_open_volume(efi_loaded_image_t *image,
efi_file_protocol_t **__fh)
{
efi_simple_file_system_protocol_t *io;
efi_file_protocol_t *fh;
efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
efi_status_t status;
efi_handle_t handle = image->device_handle;

status = efi_bs_call(handle_protocol, handle, &fs_proto, (void **)&io);
if (status != EFI_SUCCESS) {
efi_printk("Failed to handle fs_proto\n");
return status;
}

status = io->open_volume(io, &fh);
if (status != EFI_SUCCESS)
efi_printk("Failed to open volume\n");
else
*__fh = fh;

return status;
}

/*
* Parse the ASCII string 'cmdline' for EFI options, denoted by the efi=
* option, e.g. efi=nochunk.
Expand Down Expand Up @@ -197,7 +96,7 @@ efi_status_t efi_parse_options(char const *cmdline)
while (*str && *str != ' ') {
if (!strncmp(str, "nochunk", 7)) {
str += strlen("nochunk");
efi_chunk_size = -1UL;
efi_nochunk = true;
}

if (!strncmp(str, "novamap", 7)) {
Expand Down Expand Up @@ -232,187 +131,6 @@ efi_status_t efi_parse_options(char const *cmdline)
return EFI_SUCCESS;
}

/*
* Check the cmdline for a LILO-style file= arguments.
*
* We only support loading a file from the same filesystem as
* the kernel image.
*/
efi_status_t handle_cmdline_files(efi_loaded_image_t *image,
char *cmd_line, char *option_string,
unsigned long max_addr,
unsigned long *load_addr,
unsigned long *load_size)
{
struct file_info *files;
unsigned long file_addr;
u64 file_size_total;
efi_file_protocol_t *fh = NULL;
efi_status_t status;
int nr_files;
char *str;
int i, j, k;

file_addr = 0;
file_size_total = 0;

str = cmd_line;

j = 0; /* See close_handles */

if (!load_addr || !load_size)
return EFI_INVALID_PARAMETER;

*load_addr = 0;
*load_size = 0;

if (!str || !*str)
return EFI_SUCCESS;

for (nr_files = 0; *str; nr_files++) {
str = strstr(str, option_string);
if (!str)
break;

str += strlen(option_string);

/* Skip any leading slashes */
while (*str == '/' || *str == '\\')
str++;

while (*str && *str != ' ' && *str != '\n')
str++;
}

if (!nr_files)
return EFI_SUCCESS;

status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
nr_files * sizeof(*files), (void **)&files);
if (status != EFI_SUCCESS) {
pr_efi_err("Failed to alloc mem for file handle list\n");
goto fail;
}

str = cmd_line;
for (i = 0; i < nr_files; i++) {
struct file_info *file;
efi_char16_t filename_16[256];
efi_char16_t *p;

str = strstr(str, option_string);
if (!str)
break;

str += strlen(option_string);

file = &files[i];
p = filename_16;

/* Skip any leading slashes */
while (*str == '/' || *str == '\\')
str++;

while (*str && *str != ' ' && *str != '\n') {
if ((u8 *)p >= (u8 *)filename_16 + sizeof(filename_16))
break;

if (*str == '/') {
*p++ = '\\';
str++;
} else {
*p++ = *str++;
}
}

*p = '\0';

/* Only open the volume once. */
if (!i) {
status = efi_open_volume(image, &fh);
if (status != EFI_SUCCESS)
goto free_files;
}

status = efi_file_size(fh, filename_16, (void **)&file->handle,
&file->size);
if (status != EFI_SUCCESS)
goto close_handles;

file_size_total += file->size;
}

if (file_size_total) {
unsigned long addr;

/*
* Multiple files need to be at consecutive addresses in memory,
* so allocate enough memory for all the files. This is used
* for loading multiple files.
*/
status = efi_allocate_pages(file_size_total, &file_addr, max_addr);
if (status != EFI_SUCCESS) {
pr_efi_err("Failed to alloc highmem for files\n");
goto close_handles;
}

/* We've run out of free low memory. */
if (file_addr > max_addr) {
pr_efi_err("We've run out of free low memory\n");
status = EFI_INVALID_PARAMETER;
goto free_file_total;
}

addr = file_addr;
for (j = 0; j < nr_files; j++) {
unsigned long size;

size = files[j].size;
while (size) {
unsigned long chunksize;

if (IS_ENABLED(CONFIG_X86) && size > efi_chunk_size)
chunksize = efi_chunk_size;
else
chunksize = size;

status = efi_file_read(files[j].handle,
&chunksize,
(void *)addr);
if (status != EFI_SUCCESS) {
pr_efi_err("Failed to read file\n");
goto free_file_total;
}
addr += chunksize;
size -= chunksize;
}

efi_file_close(files[j].handle);
}

}

efi_bs_call(free_pool, files);

*load_addr = file_addr;
*load_size = file_size_total;

return status;

free_file_total:
efi_free(file_size_total, file_addr);

close_handles:
for (k = j; k < i; k++)
efi_file_close(files[k].handle);
free_files:
efi_bs_call(free_pool, files);
fail:
*load_addr = 0;
*load_size = 0;

return status;
}
/*
* Get the number of UTF-8 bytes corresponding to an UTF-16 character.
* This overestimates for surrogates, but that is okay.
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1 change: 1 addition & 0 deletions drivers/firmware/efi/libstub/efistub.h
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@
#define __efistub_global
#endif

extern bool __pure nochunk(void);
extern bool __pure nokaslr(void);
extern bool __pure is_quiet(void);
extern bool __pure novamap(void);
Expand Down
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