[PATCH 1/2] malloc: implement malloc_usable_size()

[PATCH 1/2] malloc: implement malloc_usable_size()

[Sascha Hauer]

malloc_usable_size() is a standard libc function. Implement it for the
barebox allocators, dlmalloc and tlsf_malloc.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 common/dlmalloc.c    | 12 ++++++++++++
 common/tlsf_malloc.c | 11 +++++++++++
 include/malloc.h     |  1 +
 3 files changed, 24 insertions(+)

diff --git a/common/dlmalloc.c b/common/dlmalloc.c
index c41487d54b..99f666aada 100644
--- a/common/dlmalloc.c
+++ b/common/dlmalloc.c
@@ -1431,6 +1431,18 @@ void free(void *mem)
 		frontlink(p, sz, idx, bck, fwd);
 }
 
+size_t malloc_usable_size(void *mem)
+{
+	mchunkptr p;
+	size_t size;
+
+	if (!mem)
+		return 0;
+
+	p = mem2chunk(mem);
+	return chunksize(p);
+}
+
 /*
   Realloc algorithm:
 
diff --git a/common/tlsf_malloc.c b/common/tlsf_malloc.c
index 981f09de41..f07ef5645b 100644
--- a/common/tlsf_malloc.c
+++ b/common/tlsf_malloc.c
@@ -38,6 +38,17 @@ void free(void *mem)
 }
 EXPORT_SYMBOL(free);
 
+size_t malloc_usable_size(void *mem)
+{
+	size_t size;
+
+	if (!mem)
+		return 0;
+
+	return tlsf_block_size(mem);
+}
+EXPORT_SYMBOL(malloc_usable_size);
+
 void *realloc(void *oldmem, size_t bytes)
 {
 	void *mem = tlsf_realloc(tlsf_mem_pool, oldmem, bytes);
diff --git a/include/malloc.h b/include/malloc.h
index d63853b91e..5cdff0a4f9 100644
--- a/include/malloc.h
+++ b/include/malloc.h
@@ -6,6 +6,7 @@
 #include <types.h>
 
 void *malloc(size_t) __alloc_size(1);
+size_t malloc_usable_size(void *);
 void free(void *);
 void *realloc(void *, size_t) __realloc_size(2);
 void *memalign(size_t, size_t) __alloc_size(2);
-- 
2.39.2

[PATCH 2/2] malloc: implement free_sensitive()

[Sascha Hauer]

barebox sometimes stores sensitive data in memory. Add a
(k)free_sensitive() function which zeroes out the memory before freeing it.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 common/Makefile      |  1 +
 common/malloc.c      | 14 ++++++++++++++
 include/dma.h        |  5 +++++
 include/linux/slab.h |  5 +++++
 include/malloc.h     |  1 +
 5 files changed, 26 insertions(+)
 create mode 100644 common/malloc.c

diff --git a/common/Makefile b/common/Makefile
index 96498790b3..e88f60b6d7 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -52,6 +52,7 @@ obj-$(CONFIG_MALLOC_DLMALLOC)	+= dlmalloc.o
 obj-$(CONFIG_MALLOC_TLSF)	+= tlsf_malloc.o tlsf.o calloc.o
 KASAN_SANITIZE_tlsf.o := n
 obj-$(CONFIG_MALLOC_DUMMY)	+= dummy_malloc.o calloc.o
+obj-y				+= malloc.o
 obj-$(CONFIG_MEMINFO)		+= meminfo.o
 obj-$(CONFIG_MENU)		+= menu.o
 obj-$(CONFIG_MODULES)		+= module.o
diff --git a/common/malloc.c b/common/malloc.c
new file mode 100644
index 0000000000..9dbad98701
--- /dev/null
+++ b/common/malloc.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <malloc.h>
+#include <string.h>
+
+void free_sensitive(void *mem)
+{
+	size_t size = malloc_usable_size(mem);
+
+	if (size)
+		memzero_explicit(mem, size);
+
+	free(mem);
+}
diff --git a/include/dma.h b/include/dma.h
index 4fcd114bb6..c2b1bee358 100644
--- a/include/dma.h
+++ b/include/dma.h
@@ -41,6 +41,11 @@ static inline void dma_free(void *mem)
 	free(mem);
 }
 
+static inline void dma_free_sensitive(void *mem)
+{
+	free_sensitive(mem);
+}
+
 #define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
 
 #define DMA_MASK_NONE	0x0ULL
diff --git a/include/linux/slab.h b/include/linux/slab.h
index a63aad1c34..5e08c7697d 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -62,6 +62,11 @@ static inline void kfree(const void *mem)
 	dma_free((void *)mem);
 }
 
+static inline void kfree_sensitive(const void *objp)
+{
+	dma_free_sensitive((void *)objp);
+}
+
 static inline void *kmem_cache_alloc(struct kmem_cache *cache, gfp_t flags)
 {
 	void *mem = kmalloc(cache->size, flags);
diff --git a/include/malloc.h b/include/malloc.h
index 5cdff0a4f9..fc0c94855e 100644
--- a/include/malloc.h
+++ b/include/malloc.h
@@ -8,6 +8,7 @@
 void *malloc(size_t) __alloc_size(1);
 size_t malloc_usable_size(void *);
 void free(void *);
+void free_sensitive(void *);
 void *realloc(void *, size_t) __realloc_size(2);
 void *memalign(size_t, size_t) __alloc_size(2);
 void *calloc(size_t, size_t) __alloc_size(1, 2);
-- 
2.39.2

[PATCH] fixup! malloc: implement malloc_usable_size()

[Ahmad Fatoum]

 - Prevent sandbox from using libc function inadvertently
 - Implement wrapper for libc malloc
 - Implement for dummy_malloc

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/sandbox/Makefile         | 1 +
 arch/sandbox/os/libc_malloc.c | 5 +++++
 common/dummy_malloc.c         | 5 +++++
 3 files changed, 11 insertions(+)

diff --git a/arch/sandbox/Makefile b/arch/sandbox/Makefile
index d5327d44e097..5c51f2de38b3 100644
--- a/arch/sandbox/Makefile
+++ b/arch/sandbox/Makefile
@@ -23,6 +23,7 @@ lds-y   := $(BOARD)/barebox.lds
 TEXT_BASE = $(CONFIG_TEXT_BASE)
 KBUILD_CFLAGS += -Dmalloc=barebox_malloc -Dcalloc=barebox_calloc \
 		-Dmalloc_stats=barebox_malloc_stats -Dmemalign=barebox_memalign \
+		-Dmalloc_usable_size=barebox_malloc_usable_size \
 		-Dfree=barebox_free -Drealloc=barebox_realloc \
 		-Dread=barebox_read -Dwrite=barebox_write \
 		-Dopen=barebox_open -Dclose=barebox_close \
diff --git a/arch/sandbox/os/libc_malloc.c b/arch/sandbox/os/libc_malloc.c
index 975c41b0ec49..e34156cd49e7 100644
--- a/arch/sandbox/os/libc_malloc.c
+++ b/arch/sandbox/os/libc_malloc.c
@@ -32,6 +32,11 @@ void *barebox_malloc(size_t size)
 	return mem;
 }
 
+size_t barebox_malloc_usable_size(void *mem)
+{
+	return malloc_usable_size(mem);
+}
+
 void barebox_free(void *ptr)
 {
 	free(ptr);
diff --git a/common/dummy_malloc.c b/common/dummy_malloc.c
index 7a96afec76e0..140ba314272a 100644
--- a/common/dummy_malloc.c
+++ b/common/dummy_malloc.c
@@ -30,6 +30,11 @@ void free(void *ptr)
 {
 }
 
+size_t malloc_usable_size(void *mem)
+{
+	BUG();
+}
+
 void *realloc(void *ptr, size_t size)
 {
 	BUG();
-- 
2.39.2

Re: (subset) [PATCH] fixup! malloc: implement malloc_usable_size()

[Sascha Hauer]

On Tue, 06 Aug 2024 14:56:58 +0200, Ahmad Fatoum wrote:
>  - Prevent sandbox from using libc function inadvertently
>  - Implement wrapper for libc malloc
>  - Implement for dummy_malloc
> 
> 

Applied, thanks!

[1/1] fixup! malloc: implement malloc_usable_size()
      https://git.pengutronix.de/cgit/barebox/commit/?id=973c53ae6bc7 (link may not be stable)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>

Re: [PATCH 1/2] malloc: implement malloc_usable_size()

[Sascha Hauer]

On Tue, 06 Aug 2024 12:54:28 +0200, Sascha Hauer wrote:
> malloc_usable_size() is a standard libc function. Implement it for the
> barebox allocators, dlmalloc and tlsf_malloc.
> 
> 

Applied, thanks!

[1/2] malloc: implement malloc_usable_size()
      https://git.pengutronix.de/cgit/barebox/commit/?id=c89226c58ac3 (link may not be stable)
[2/2] malloc: implement free_sensitive()
      https://git.pengutronix.de/cgit/barebox/commit/?id=47ff229f3fae (link may not be stable)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>