diff --git a/include/uapi/linux/module.h b/include/uapi/linux/module.h
index 50d98ec5e8668b1379202866d5791bebb6fb685d..03a33ffffcba886b232606b3da9976e03f96308e 100644
--- a/include/uapi/linux/module.h
+++ b/include/uapi/linux/module.h
@@ -5,5 +5,6 @@
/* Flags for sys_finit_module: */
#define MODULE_INIT_IGNORE_MODVERSIONS 1
#define MODULE_INIT_IGNORE_VERMAGIC 2
+#define MODULE_INIT_COMPRESSED_FILE 4
#endif /* _UAPI_LINUX_MODULE_H */
diff --git a/init/Kconfig b/init/Kconfig
index 4b7bac10c72d30db71b12347cb5d6c290ae8c156..ad386eac1210982d50567e991c8867aa9300e688 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2280,6 +2280,19 @@ config MODULE_COMPRESS_ZSTD
endchoice
+config MODULE_DECOMPRESS
+ bool "Support in-kernel module decompression"
+ depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ
+ select ZLIB_INFLATE if MODULE_COMPRESS_GZIP
+ select XZ_DEC if MODULE_COMPRESS_XZ
+ help
+
+ Support for decompressing kernel modules by the kernel itself
+ instead of relying on userspace to perform this task. Useful when
+ load pinning security policy is enabled.
+
+ If unsure, say N.
+
config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
bool "Allow loading of modules with missing namespace imports"
help
diff --git a/kernel/Makefile b/kernel/Makefile
index 186c49582f45b65e8ab284905203cbe95b6e5d5e..56f4ee97f32849823304b0b3b6509b33a4cca6e7 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -67,6 +67,7 @@ obj-y += up.o
endif
obj-$(CONFIG_UID16) += uid16.o
obj-$(CONFIG_MODULES) += module.o
+obj-$(CONFIG_MODULE_DECOMPRESS) += module_decompress.o
obj-$(CONFIG_MODULE_SIG) += module_signing.o
obj-$(CONFIG_MODULE_SIG_FORMAT) += module_signature.o
obj-$(CONFIG_KALLSYMS) += kallsyms.o
diff --git a/kernel/module-internal.h b/kernel/module-internal.h
index 33783abc377bfb5333a8da30601134f4265dbcea..8c381c99062f2d38443dbdbf5ea9e634c23fc6f0 100644
--- a/kernel/module-internal.h
+++ b/kernel/module-internal.h
@@ -22,6 +22,11 @@ struct load_info {
bool sig_ok;
#ifdef CONFIG_KALLSYMS
unsigned long mod_kallsyms_init_off;
+#endif
+#ifdef CONFIG_MODULE_DECOMPRESS
+ struct page **pages;
+ unsigned int max_pages;
+ unsigned int used_pages;
#endif
struct {
unsigned int sym, str, mod, vers, info, pcpu;
@@ -29,3 +34,17 @@ struct load_info {
};
extern int mod_verify_sig(const void *mod, struct load_info *info);
+
+#ifdef CONFIG_MODULE_DECOMPRESS
+int module_decompress(struct load_info *info, const void *buf, size_t size);
+void module_decompress_cleanup(struct load_info *info);
+#else
+static inline int module_decompress(struct load_info *info,
+ const void *buf, size_t size)
+{
+ return -EOPNOTSUPP;
+}
+static inline void module_decompress_cleanup(struct load_info *info)
+{
+}
+#endif
diff --git a/kernel/module.c b/kernel/module.c
index 84a9141a5e159a01642c6a67e4250e016de39797..a7c5490b41e9e8228237932e6535e2c054c54ef5 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3174,9 +3174,12 @@ static int copy_module_from_user(const void __user *umod, unsigned long len,
return err;
}
-static void free_copy(struct load_info *info)
+static void free_copy(struct load_info *info, int flags)
{
- vfree(info->hdr);
+ if (flags & MODULE_INIT_COMPRESSED_FILE)
+ module_decompress_cleanup(info);
+ else
+ vfree(info->hdr);
}
static int rewrite_section_headers(struct load_info *info, int flags)
@@ -4125,7 +4128,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
}
/* Get rid of temporary copy. */
- free_copy(info);
+ free_copy(info, flags);
/* Done! */
trace_module_load(mod);
@@ -4174,7 +4177,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
module_deallocate(mod, info);
free_copy:
- free_copy(info);
+ free_copy(info, flags);
return err;
}
@@ -4201,7 +4204,8 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
{
struct load_info info = { };
- void *hdr = NULL;
+ void *buf = NULL;
+ int len;
int err;
err = may_init_module();
@@ -4211,15 +4215,24 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
pr_debug("finit_module: fd=%d, uargs=%p, flags=%i\n", fd, uargs, flags);
if (flags & ~(MODULE_INIT_IGNORE_MODVERSIONS
- |MODULE_INIT_IGNORE_VERMAGIC))
+ |MODULE_INIT_IGNORE_VERMAGIC
+ |MODULE_INIT_COMPRESSED_FILE))
return -EINVAL;
- err = kernel_read_file_from_fd(fd, 0, &hdr, INT_MAX, NULL,
+ len = kernel_read_file_from_fd(fd, 0, &buf, INT_MAX, NULL,
READING_MODULE);
- if (err < 0)
- return err;
- info.hdr = hdr;
- info.len = err;
+ if (len < 0)
+ return len;
+
+ if (flags & MODULE_INIT_COMPRESSED_FILE) {
+ err = module_decompress(&info, buf, len);
+ vfree(buf); /* compressed data is no longer needed */
+ if (err)
+ return err;
+ } else {
+ info.hdr = buf;
+ info.len = len;
+ }
return load_module(&info, uargs, flags);
}
diff --git a/kernel/module_decompress.c b/kernel/module_decompress.c
new file mode 100644
index 0000000000000000000000000000000000000000..aeefd95a33375c304104288ed84e2a198accba1f
--- /dev/null
+++ b/kernel/module_decompress.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2021 Google LLC.
+ */
+
+#include <linux/init.h>
+#include <linux/highmem.h>
+#include <linux/kobject.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/vmalloc.h>
+
+#include "module-internal.h"
+
+static int module_extend_max_pages(struct load_info *info, unsigned int extent)
+{
+ struct page **new_pages;
+
+ new_pages = kvmalloc_array(info->max_pages + extent,
+ sizeof(info->pages), GFP_KERNEL);
+ if (!new_pages)
+ return -ENOMEM;
+
+ memcpy(new_pages, info->pages, info->max_pages * sizeof(info->pages));
+ kvfree(info->pages);
+ info->pages = new_pages;
+ info->max_pages += extent;
+
+ return 0;
+}
+
+static struct page *module_get_next_page(struct load_info *info)
+{
+ struct page *page;
+ int error;
+
+ if (info->max_pages == info->used_pages) {
+ error = module_extend_max_pages(info, info->used_pages);
+ if (error)
+ return ERR_PTR(error);
+ }
+
+ page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
+ if (!page)
+ return ERR_PTR(-ENOMEM);
+
+ info->pages[info->used_pages++] = page;
+ return page;
+}
+
+#ifdef CONFIG_MODULE_COMPRESS_GZIP
+#include <linux/zlib.h>
+#define MODULE_COMPRESSION gzip
+#define MODULE_DECOMPRESS_FN module_gzip_decompress
+
+/*
+ * Calculate length of the header which consists of signature, header
+ * flags, time stamp and operating system ID (10 bytes total), plus
+ * an optional filename.
+ */
+static size_t module_gzip_header_len(const u8 *buf, size_t size)
+{
+ const u8 signature[] = { 0x1f, 0x8b, 0x08 };
+ size_t len = 10;
+
+ if (size < len || memcmp(buf, signature, sizeof(signature)))
+ return 0;
+
+ if (buf[3] & 0x08) {
+ do {
+ /*
+ * If we can't find the end of the file name we must
+ * be dealing with a corrupted file.
+ */
+ if (len == size)
+ return 0;
+ } while (buf[len++] != '\0');
+ }
+
+ return len;
+}
+
+static ssize_t module_gzip_decompress(struct load_info *info,
+ const void *buf, size_t size)
+{
+ struct z_stream_s s = { 0 };
+ size_t new_size = 0;
+ size_t gzip_hdr_len;
+ ssize_t retval;
+ int rc;
+
+ gzip_hdr_len = module_gzip_header_len(buf, size);
+ if (!gzip_hdr_len) {
+ pr_err("not a gzip compressed module\n");
+ return -EINVAL;
+ }
+
+ s.next_in = buf + gzip_hdr_len;
+ s.avail_in = size - gzip_hdr_len;
+
+ s.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
+ if (!s.workspace)
+ return -ENOMEM;
+
+ rc = zlib_inflateInit2(&s, -MAX_WBITS);
+ if (rc != Z_OK) {
+ pr_err("failed to initialize decompresser: %d\n", rc);
+ retval = -EINVAL;
+ goto out;
+ }
+
+ do {
+ struct page *page = module_get_next_page(info);
+ if (!page) {
+ retval = -ENOMEM;
+ goto out_inflate_end;
+ }
+
+ s.next_out = kmap(page);
+ s.avail_out = PAGE_SIZE;
+ rc = zlib_inflate(&s, 0);
+ kunmap(page);
+
+ new_size += PAGE_SIZE - s.avail_out;
+ } while (rc == Z_OK);
+
+ if (rc != Z_STREAM_END) {
+ pr_err("decompression failed with status %d\n", rc);
+ retval = -EINVAL;
+ goto out_inflate_end;
+ }
+
+ retval = new_size;
+
+out_inflate_end:
+ zlib_inflateEnd(&s);
+out:
+ kfree(s.workspace);
+ return retval;
+}
+#elif CONFIG_MODULE_COMPRESS_XZ
+#include <linux/xz.h>
+#define MODULE_COMPRESSION xz
+#define MODULE_DECOMPRESS_FN module_xz_decompress
+
+static ssize_t module_xz_decompress(struct load_info *info,
+ const void *buf, size_t size)
+{
+ static const u8 signature[] = { 0xfd, '7', 'z', 'X', 'Z', 0 };
+ struct xz_dec *xz_dec;
+ struct xz_buf xz_buf;
+ enum xz_ret xz_ret;
+ size_t new_size = 0;
+ ssize_t retval;
+
+ if (size < sizeof(signature) ||
+ memcmp(buf, signature, sizeof(signature))) {
+ pr_err("not an xz compressed module\n");
+ return -EINVAL;
+ }
+
+ xz_dec = xz_dec_init(XZ_DYNALLOC, (u32)-1);
+ if (!xz_dec)
+ return -ENOMEM;
+
+ xz_buf.in_size = size;
+ xz_buf.in = buf;
+ xz_buf.in_pos = 0;
+
+ do {
+ struct page *page = module_get_next_page(info);
+ if (!page) {
+ retval = -ENOMEM;
+ goto out;
+ }
+
+ xz_buf.out = kmap(page);
+ xz_buf.out_pos = 0;
+ xz_buf.out_size = PAGE_SIZE;
+ xz_ret = xz_dec_run(xz_dec, &xz_buf);
+ kunmap(page);
+
+ new_size += xz_buf.out_pos;
+ } while (xz_buf.out_pos == PAGE_SIZE && xz_ret == XZ_OK);
+
+ if (xz_ret != XZ_STREAM_END) {
+ pr_err("decompression failed with status %d\n", xz_ret);
+ retval = -EINVAL;
+ goto out;
+ }
+
+ retval = new_size;
+
+ out:
+ xz_dec_end(xz_dec);
+ return retval;
+}
+#else
+#error "Unexpected configuration for CONFIG_MODULE_DECOMPRESS"
+#endif
+
+int module_decompress(struct load_info *info, const void *buf, size_t size)
+{
+ unsigned int n_pages;
+ ssize_t data_size;
+ int error;
+
+ /*
+ * Start with number of pages twice as big as needed for
+ * compressed data.
+ */
+ n_pages = DIV_ROUND_UP(size, PAGE_SIZE) * 2;
+ error = module_extend_max_pages(info, n_pages);
+
+ data_size = MODULE_DECOMPRESS_FN(info, buf, size);
+ if (data_size < 0) {
+ error = data_size;
+ goto err;
+ }
+
+ info->hdr = vmap(info->pages, info->used_pages, VM_MAP, PAGE_KERNEL);
+ if (!info->hdr) {
+ error = -ENOMEM;
+ goto err;
+ }
+
+ info->len = data_size;
+ return 0;
+
+err:
+ module_decompress_cleanup(info);
+ return error;
+}
+
+void module_decompress_cleanup(struct load_info *info)
+{
+ int i;
+
+ if (info->hdr)
+ vunmap(info->hdr);
+
+ for (i = 0; i < info->used_pages; i++)
+ __free_page(info->pages[i]);
+
+ kvfree(info->pages);
+
+ info->pages = NULL;
+ info->max_pages = info->used_pages = 0;
+}
+
+static ssize_t compression_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%s\n", __stringify(MODULE_COMPRESSION));
+}
+static struct kobj_attribute module_compression_attr = __ATTR_RO(compression);
+
+static int __init module_decompress_sysfs_init(void)
+{
+ int error;
+
+ error = sysfs_create_file(&module_kset->kobj,
+ &module_compression_attr.attr);
+ if (error)
+ pr_warn("Failed to create 'compression' attribute");
+
+ return 0;
+}
+late_initcall(module_decompress_sysfs_init);