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authorMike Frysinger2016-09-15 12:16:33 +0200
committerDenys Vlasenko2016-09-15 12:16:33 +0200
commit3a45b87ac36f60962d6d19c592813e186a9e82e6 (patch)
tree2b3d2249ff2e558bc92a71f91339474a50a0b596 /modutils
parent7fa799a97d381902ab27556918722a6e2d138b9e (diff)
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modutils: support finit_module syscall
On some systems like Chromium OS, loading modules from non-verified filesystems is denied. Only finit_module is allowed because an open fd is passed which can be checked against a verified location. Change the module loading code to first attempt finit_module and if that fails for whatever reason, fall back to the existing logic. On x86_64, this adds ~80 bytes to modutils/modutils.o and ~68 bytes to modutils/modprobe-small.o. Signed-off-by: Mike Frysinger <vapier@chromium.org> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'modutils')
-rw-r--r--modutils/modprobe-small.c33
-rw-r--r--modutils/modutils.c21
2 files changed, 51 insertions, 3 deletions
diff --git a/modutils/modprobe-small.c b/modutils/modprobe-small.c
index 5936e48..a47e522 100644
--- a/modutils/modprobe-small.c
+++ b/modutils/modprobe-small.c
@@ -18,9 +18,13 @@
/* After libbb.h, since it needs sys/types.h on some systems */
#include <sys/utsname.h> /* uname() */
#include <fnmatch.h>
+#include <sys/syscall.h>
extern int init_module(void *module, unsigned long len, const char *options);
extern int delete_module(const char *module, unsigned flags);
+#ifdef __NR_finit_module
+# define finit_module(fd, uargs, flags) syscall(__NR_finit_module, fd, uargs, flags)
+#endif
/* linux/include/linux/module.h has limit of 64 chars on module names */
#undef MODULE_NAME_LEN
#define MODULE_NAME_LEN 64
@@ -209,11 +213,34 @@ static int load_module(const char *fname, const char *options)
int r;
size_t len = MAXINT(ssize_t);
char *module_image;
+
+ if (!options)
+ options = "";
+
dbg1_error_msg("load_module('%s','%s')", fname, options);
- module_image = xmalloc_open_zipped_read_close(fname, &len);
- r = (!module_image || init_module(module_image, len, options ? options : "") != 0);
- free(module_image);
+ /*
+ * First we try finit_module if available. Some kernels are configured
+ * to only allow loading of modules off of secure storage (like a read-
+ * only rootfs) which needs the finit_module call. If it fails, we fall
+ * back to normal module loading to support compressed modules.
+ */
+ r = 1;
+# ifdef __NR_finit_module
+ {
+ int fd = open(fname, O_RDONLY | O_CLOEXEC);
+ if (fd >= 0) {
+ r = finit_module(fd, options, 0) != 0;
+ close(fd);
+ }
+ }
+# endif
+ if (r != 0) {
+ module_image = xmalloc_open_zipped_read_close(fname, &len);
+ r = (!module_image || init_module(module_image, len, options) != 0);
+ free(module_image);
+ }
+
dbg1_error_msg("load_module:%d", r);
return r; /* 0 = success */
#else
diff --git a/modutils/modutils.c b/modutils/modutils.c
index 0a05673..d36caaf 100644
--- a/modutils/modutils.c
+++ b/modutils/modutils.c
@@ -13,6 +13,9 @@ extern int delete_module(const char *module, unsigned int flags);
#else
# include <sys/syscall.h>
# define init_module(mod, len, opts) syscall(__NR_init_module, mod, len, opts)
+# if defined(__NR_finit_module)
+# define finit_module(fd, uargs, flags) syscall(__NR_finit_module, fd, uargs, flags)
+# endif
# define delete_module(mod, flags) syscall(__NR_delete_module, mod, flags)
#endif
@@ -212,6 +215,24 @@ int FAST_FUNC bb_init_module(const char *filename, const char *options)
return bb_init_module_24(filename, options);
#endif
+ /*
+ * First we try finit_module if available. Some kernels are configured
+ * to only allow loading of modules off of secure storage (like a read-
+ * only rootfs) which needs the finit_module call. If it fails, we fall
+ * back to normal module loading to support compressed modules.
+ */
+# ifdef __NR_finit_module
+ {
+ int fd = open(filename, O_RDONLY | O_CLOEXEC);
+ if (fd >= 0) {
+ rc = finit_module(fd, options, 0) != 0;
+ close(fd);
+ if (rc == 0)
+ return rc;
+ }
+ }
+# endif
+
image_size = INT_MAX - 4095;
mmaped = 0;
image = try_to_mmap_module(filename, &image_size);