binfmt_flat: allow compressed flat binary format to work on MMU systems

Let's take the simple and obvious approach by decompressing the binary into a kernel buffer and then copying it to user space. Those who are looking for top performance on an MMU system are unlikely to choose this executable format anyway. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Greg Ungerer <gerg@linux-m68k.org> Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>

binfmt_flat: allow compressed flat binary format to work on MMU systems
Let's take the simple and obvious approach by decompressing the binary into a kernel buffer and then copying it to user space. Those who are looking for top performance on an MMU system are unlikely to choose this executable format anyway. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Greg Ungerer <gerg@linux-m68k.org> Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
Nicolas Pitre · Greg Ungerer
1 parent 015feacf93
Showing 1 changed file with 42 additions and 2 deletions Side-by-side Diff
fs/binfmt_flat.c
@@ -34,6 +34,7 @@
 #include <linux/init.h>
 #include <linux/flat.h>
 #include <linux/uaccess.h>
+#include <linux/vmalloc.h>
  
 #include <asm/byteorder.h>
 #include <asm/unaligned.h>
@@ -628,6 +629,7 @@
 		 * load it all in and treat it like a RAM load from now on
 		 */
 		if (flags & FLAT_FLAG_GZIP) {
+#ifndef CONFIG_MMU
 			result = decompress_exec(bprm, sizeof(struct flat_hdr),
 					 (((char *)textpos) + sizeof(struct flat_hdr)),
 					 (text_len + full_data
  
  
  
@@ -635,13 +637,51 @@
 					 0);
 			memmove((void *) datapos, (void *) realdatastart,
 					full_data);
+#else
+			/*
+			 * This is used on MMU systems mainly for testing.
+			 * Let's use a kernel buffer to simplify things.
+			 */
+			long unz_text_len = text_len - sizeof(struct flat_hdr);
+			long unz_len = unz_text_len + full_data;
+			char *unz_data = vmalloc(unz_len);
+			if (!unz_data) {
+				result = -ENOMEM;
+			} else {
+				result = decompress_exec(bprm, sizeof(struct flat_hdr),
+							 unz_data, unz_len, 0);
+				if (result == 0 &&
+				    (copy_to_user((void __user *)textpos + sizeof(struct flat_hdr),
+						  unz_data, unz_text_len) ||
+				     copy_to_user((void __user *)datapos,
+						  unz_data + unz_text_len, full_data)))
+					result = -EFAULT;
+				vfree(unz_data);
+			}
+#endif
 		} else if (flags & FLAT_FLAG_GZDATA) {
 			result = read_code(bprm->file, textpos, 0, text_len);
-			if (!IS_ERR_VALUE(result))
+			if (!IS_ERR_VALUE(result)) {
+#ifndef CONFIG_MMU
 				result = decompress_exec(bprm, text_len, (char *) datapos,
 						 full_data, 0);
-		} else
+#else
+				char *unz_data = vmalloc(full_data);
+				if (!unz_data) {
+					result = -ENOMEM;
+				} else {
+					result = decompress_exec(bprm, text_len,
+						       unz_data, full_data, 0);
+					if (result == 0 &&
+					    copy_to_user((void __user *)datapos,
+							 unz_data, full_data))
+						result = -EFAULT;
+					vfree(unz_data);
+				}
 #endif
+			}
+		} else
+#endif /* CONFIG_BINFMT_ZFLAT */
 		{
 			result = read_code(bprm->file, textpos, 0, text_len);
 			if (!IS_ERR_VALUE(result))
...	...	@@ -34,6 +34,7 @@
34	34	#include <linux/init.h>
35	35	#include <linux/flat.h>
36	36	#include <linux/uaccess.h>
	37	+#include <linux/vmalloc.h>
37	38
38	39	#include <asm/byteorder.h>
39	40	#include <asm/unaligned.h>
...	...	@@ -628,6 +629,7 @@
628	629	* load it all in and treat it like a RAM load from now on
629	630	*/
630	631	if (flags & FLAT_FLAG_GZIP) {
	632	+#ifndef CONFIG_MMU
631	633	result = decompress_exec(bprm, sizeof(struct flat_hdr),
632	634	(((char *)textpos) + sizeof(struct flat_hdr)),
633	635	(text_len + full_data
634	636
635	637
636	638
...	...	@@ -635,13 +637,51 @@
635	637	0);
636	638	memmove((void ) datapos, (void ) realdatastart,
637	639	full_data);
	640	+#else
	641	+ /*
	642	+ * This is used on MMU systems mainly for testing.
	643	+ * Let's use a kernel buffer to simplify things.
	644	+ */
	645	+ long unz_text_len = text_len - sizeof(struct flat_hdr);
	646	+ long unz_len = unz_text_len + full_data;
	647	+ char *unz_data = vmalloc(unz_len);
	648	+ if (!unz_data) {
	649	+ result = -ENOMEM;
	650	+ } else {
	651	+ result = decompress_exec(bprm, sizeof(struct flat_hdr),
	652	+ unz_data, unz_len, 0);
	653	+ if (result == 0 &&
	654	+ (copy_to_user((void __user *)textpos + sizeof(struct flat_hdr),
	655	+ unz_data, unz_text_len) \|\|
	656	+ copy_to_user((void __user *)datapos,
	657	+ unz_data + unz_text_len, full_data)))
	658	+ result = -EFAULT;
	659	+ vfree(unz_data);
	660	+ }
	661	+#endif
638	662	} else if (flags & FLAT_FLAG_GZDATA) {
639	663	result = read_code(bprm->file, textpos, 0, text_len);
640		- if (!IS_ERR_VALUE(result))
	664	+ if (!IS_ERR_VALUE(result)) {
	665	+#ifndef CONFIG_MMU
641	666	result = decompress_exec(bprm, text_len, (char *) datapos,
642	667	full_data, 0);
643		- } else
	668	+#else
	669	+ char *unz_data = vmalloc(full_data);
	670	+ if (!unz_data) {
	671	+ result = -ENOMEM;
	672	+ } else {
	673	+ result = decompress_exec(bprm, text_len,
	674	+ unz_data, full_data, 0);
	675	+ if (result == 0 &&
	676	+ copy_to_user((void __user *)datapos,
	677	+ unz_data, full_data))
	678	+ result = -EFAULT;
	679	+ vfree(unz_data);
	680	+ }
644	681	#endif
	682	+ }
	683	+ } else
	684	+#endif /* CONFIG_BINFMT_ZFLAT */
645	685	{
646	686	result = read_code(bprm->file, textpos, 0, text_len);
647	687	if (!IS_ERR_VALUE(result))