Re: [PATCH bpf-next v2] bpf: Check return from set_memory_rox() and friends
From: Daniel Borkmann
Date: Fri Mar 15 2024 - 10:35:29 EST
On 2/21/24 3:45 PM, Christophe Leroy wrote:
arch_protect_bpf_trampoline() and alloc_new_pack() call
set_memory_rox() which can fail, leading to unprotected memory.
Take into account return from set_memory_XX() functions and add
__must_check flag to arch_protect_bpf_trampoline().
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
v2:
- Move list_add_tail(&pack->list, &pack_list) at the end of alloc_new_pack()
- Split 2 lines that are reported longer than 80 chars by BPF patchwork's checkpatch report.
---
arch/x86/net/bpf_jit_comp.c | 6 ++++--
include/linux/bpf.h | 4 ++--
kernel/bpf/bpf_struct_ops.c | 9 +++++++--
kernel/bpf/core.c | 29 ++++++++++++++++++++++-------
kernel/bpf/trampoline.c | 18 ++++++++++++------
net/bpf/bpf_dummy_struct_ops.c | 4 +++-
6 files changed, 50 insertions(+), 20 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index e1390d1e331b..128c8ec9164e 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -2780,12 +2780,14 @@ void arch_free_bpf_trampoline(void *image, unsigned int size)
bpf_prog_pack_free(image, size);
}
-void arch_protect_bpf_trampoline(void *image, unsigned int size)
+int arch_protect_bpf_trampoline(void *image, unsigned int size)
{
+ return 0;
}
-void arch_unprotect_bpf_trampoline(void *image, unsigned int size)
+int arch_unprotect_bpf_trampoline(void *image, unsigned int size)
{
+ return 0;
}
int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end,
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b86bd15a051d..bb2723c264df 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1116,8 +1116,8 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
void *func_addr);
void *arch_alloc_bpf_trampoline(unsigned int size);
void arch_free_bpf_trampoline(void *image, unsigned int size);
-void arch_protect_bpf_trampoline(void *image, unsigned int size);
-void arch_unprotect_bpf_trampoline(void *image, unsigned int size);
+int __must_check arch_protect_bpf_trampoline(void *image, unsigned int size);
+int arch_unprotect_bpf_trampoline(void *image, unsigned int size);
int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags,
struct bpf_tramp_links *tlinks, void *func_addr);
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 0decd862dfe0..d920afb0dd60 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -488,7 +488,9 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
if (err)
goto reset_unlock;
}
- arch_protect_bpf_trampoline(st_map->image, PAGE_SIZE);
+ err = arch_protect_bpf_trampoline(st_map->image, PAGE_SIZE);
+ if (err)
+ goto reset_unlock;
/* Let bpf_link handle registration & unregistration.
*
* Pair with smp_load_acquire() during lookup_elem().
@@ -497,7 +499,10 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
goto unlock;
}
- arch_protect_bpf_trampoline(st_map->image, PAGE_SIZE);
+ err = arch_protect_bpf_trampoline(st_map->image, PAGE_SIZE);
+ if (err)
+ goto reset_unlock;
+
err = st_ops->reg(kdata);
if (likely(!err)) {
/* This refcnt increment on the map here after
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index c49619ef55d0..eb2256ba6daf 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -898,23 +898,31 @@ static LIST_HEAD(pack_list);
static struct bpf_prog_pack *alloc_new_pack(bpf_jit_fill_hole_t bpf_fill_ill_insns)
{
struct bpf_prog_pack *pack;
+ int err;
pack = kzalloc(struct_size(pack, bitmap, BITS_TO_LONGS(BPF_PROG_CHUNK_COUNT)),
GFP_KERNEL);
if (!pack)
return NULL;
pack->ptr = bpf_jit_alloc_exec(BPF_PROG_PACK_SIZE);
- if (!pack->ptr) {
- kfree(pack);
- return NULL;
- }
+ if (!pack->ptr)
+ goto out;
bpf_fill_ill_insns(pack->ptr, BPF_PROG_PACK_SIZE);
bitmap_zero(pack->bitmap, BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE);
- list_add_tail(&pack->list, &pack_list);
set_vm_flush_reset_perms(pack->ptr);
- set_memory_rox((unsigned long)pack->ptr, BPF_PROG_PACK_SIZE / PAGE_SIZE);
+ err = set_memory_rox((unsigned long)pack->ptr,
+ BPF_PROG_PACK_SIZE / PAGE_SIZE);
+ if (err)
+ goto out_free;
+ list_add_tail(&pack->list, &pack_list);
return pack;
+
+out_free:
+ bpf_jit_free_exec(pack->ptr);
+out:
+ kfree(pack);
+ return NULL;
}
void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns)
@@ -929,9 +937,16 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns)
size = round_up(size, PAGE_SIZE);
ptr = bpf_jit_alloc_exec(size);
if (ptr) {
+ int err;
+
bpf_fill_ill_insns(ptr, size);
set_vm_flush_reset_perms(ptr);
- set_memory_rox((unsigned long)ptr, size / PAGE_SIZE);
+ err = set_memory_rox((unsigned long)ptr,
+ size / PAGE_SIZE);
+ if (err) {
+ bpf_jit_free_exec(ptr);
+ ptr = NULL;
+ }
}
goto out;
}
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index d382f5ebe06c..6e64ac9083b6 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -456,7 +456,9 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
if (err < 0)
goto out_free;
- arch_protect_bpf_trampoline(im->image, im->size);
+ err = arch_protect_bpf_trampoline(im->image, im->size);
+ if (err)
+ goto out_free;
WARN_ON(tr->cur_image && total == 0);
if (tr->cur_image)
@@ -1072,17 +1074,21 @@ void __weak arch_free_bpf_trampoline(void *image, unsigned int size)
bpf_jit_free_exec(image);
}
-void __weak arch_protect_bpf_trampoline(void *image, unsigned int size)
+int __weak arch_protect_bpf_trampoline(void *image, unsigned int size)
nit: Should we add __must_check as well here?
{
WARN_ON_ONCE(size > PAGE_SIZE);
- set_memory_rox((long)image, 1);
+ return set_memory_rox((long)image, 1);
}
-void __weak arch_unprotect_bpf_trampoline(void *image, unsigned int size)
+int __weak arch_unprotect_bpf_trampoline(void *image, unsigned int size)
{
+ int err;
WARN_ON_ONCE(size > PAGE_SIZE);
- set_memory_nx((long)image, 1);
- set_memory_rw((long)image, 1);
+
+ err = set_memory_nx((long)image, 1);
+ if (err)
+ return err;
+ return set_memory_rw((long)image, 1);
}
Do we still need this? It looks like this does not have an in-tree user anymore.
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index c5b461dda438..132c8ffba109 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -2180,10 +2180,6 @@ void arch_protect_bpf_trampoline(void *image, unsigned int size)
{
}
-void arch_unprotect_bpf_trampoline(void *image, unsigned int size)
-{
-}
-
int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *ro_image,
void *ro_image_end, const struct btf_func_model *m,
u32 flags, struct bpf_tramp_links *tlinks,
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index a7ba8e178645..7a56d2d84512 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -3008,10 +3008,6 @@ void arch_protect_bpf_trampoline(void *image, unsigned int size)
{
}
-void arch_unprotect_bpf_trampoline(void *image, unsigned int size)
-{
-}
-
int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end,
const struct btf_func_model *m, u32 flags,
struct bpf_tramp_links *tlinks,
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 4f20f62f9d63..d89bdefb42e2 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1117,7 +1117,6 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
void *arch_alloc_bpf_trampoline(unsigned int size);
void arch_free_bpf_trampoline(void *image, unsigned int size);
void arch_protect_bpf_trampoline(void *image, unsigned int size);
-void arch_unprotect_bpf_trampoline(void *image, unsigned int size);
int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags,
struct bpf_tramp_links *tlinks, void *func_addr);
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index db7599c59c78..04fd1abd3661 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -1078,13 +1078,6 @@ void __weak arch_protect_bpf_trampoline(void *image, unsigned int size)
set_memory_rox((long)image, 1);
}
-void __weak arch_unprotect_bpf_trampoline(void *image, unsigned int size)
-{
- WARN_ON_ONCE(size > PAGE_SIZE);
- set_memory_nx((long)image, 1);
- set_memory_rw((long)image, 1);
-}
-
int __weak arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags,
struct bpf_tramp_links *tlinks, void *func_addr)
{