[PATCH 6.1 1/2] bpf: Add MEM_WRITE attribute

[PATCH 6.1 1/2] bpf: Add MEM_WRITE attribute

[hsimeliere.opensource]

From: Daniel Borkmann <daniel@iogearbox.net>

[ Upstream commit 6fad274f06f038c29660aa53fbad14241c9fd976 ]

Add a MEM_WRITE attribute for BPF helper functions which can be used in
bpf_func_proto to annotate an argument type in order to let the verifier
know that the helper writes into the memory passed as an argument. In
the past MEM_UNINIT has been (ab)used for this function, but the latter
merely tells the verifier that the passed memory can be uninitialized.

There have been bugs with overloading the latter but aside from that
there are also cases where the passed memory is read + written which
currently cannot be expressed, see also 4b3786a6c539 ("bpf: Zero former
ARG_PTR_TO_{LONG,INT} args in case of error").

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241021152809.33343-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: BRUNO VERNAY <bruno.vernay@se.com>
Signed-off-by: Hugo SIMELIERE <hsimeliere.opensource@witekio.com>
---
 include/linux/bpf.h      | 14 +++++++++++---
 kernel/bpf/helpers.c     | 10 +++++-----
 kernel/bpf/ringbuf.c     |  2 +-
 kernel/bpf/syscall.c     |  2 +-
 kernel/trace/bpf_trace.c |  4 ++--
 net/core/filter.c        |  4 ++--
 6 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 39291ec48374..e9c1338851e3 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -465,6 +465,7 @@ enum bpf_type_flag {
 	 */
 	PTR_UNTRUSTED		= BIT(6 + BPF_BASE_TYPE_BITS),
 
+	/* MEM can be uninitialized. */
 	MEM_UNINIT		= BIT(7 + BPF_BASE_TYPE_BITS),
 
 	/* DYNPTR points to memory local to the bpf program. */
@@ -481,6 +482,13 @@ enum bpf_type_flag {
 	 */
 	MEM_ALIGNED		= BIT(17 + BPF_BASE_TYPE_BITS),
 
+	/* MEM is being written to, often combined with MEM_UNINIT. Non-presence
+	 * of MEM_WRITE means that MEM is only being read. MEM_WRITE without the
+	 * MEM_UNINIT means that memory needs to be initialized since it is also
+	 * read.
+	 */
+	MEM_WRITE		= BIT(18 + BPF_BASE_TYPE_BITS),
+
 	__BPF_TYPE_FLAG_MAX,
 	__BPF_TYPE_LAST_FLAG	= __BPF_TYPE_FLAG_MAX - 1,
 };
@@ -538,10 +546,10 @@ enum bpf_arg_type {
 	ARG_PTR_TO_ALLOC_MEM_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_ALLOC_MEM,
 	ARG_PTR_TO_STACK_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_STACK,
 	ARG_PTR_TO_BTF_ID_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_BTF_ID,
-	/* pointer to memory does not need to be initialized, helper function must fill
-	 * all bytes or clear them in error case.
+	/* Pointer to memory does not need to be initialized, since helper function
+	 * fills all bytes or clears them in error case.
 	 */
-	ARG_PTR_TO_UNINIT_MEM		= MEM_UNINIT | ARG_PTR_TO_MEM,
+	ARG_PTR_TO_UNINIT_MEM		= MEM_UNINIT | MEM_WRITE | ARG_PTR_TO_MEM,
 	/* Pointer to valid memory of size known at compile time. */
 	ARG_PTR_TO_FIXED_SIZE_MEM	= MEM_FIXED_SIZE | ARG_PTR_TO_MEM,
 
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 14ad6856257c..4fef0a015525 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -107,7 +107,7 @@ const struct bpf_func_proto bpf_map_pop_elem_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_CONST_MAP_PTR,
-	.arg2_type	= ARG_PTR_TO_MAP_VALUE | MEM_UNINIT,
+	.arg2_type	= ARG_PTR_TO_MAP_VALUE | MEM_UNINIT | MEM_WRITE,
 };
 
 BPF_CALL_2(bpf_map_peek_elem, struct bpf_map *, map, void *, value)
@@ -120,7 +120,7 @@ const struct bpf_func_proto bpf_map_peek_elem_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_CONST_MAP_PTR,
-	.arg2_type	= ARG_PTR_TO_MAP_VALUE | MEM_UNINIT,
+	.arg2_type	= ARG_PTR_TO_MAP_VALUE | MEM_UNINIT | MEM_WRITE,
 };
 
 BPF_CALL_3(bpf_map_lookup_percpu_elem, struct bpf_map *, map, void *, key, u32, cpu)
@@ -531,7 +531,7 @@ const struct bpf_func_proto bpf_strtol_proto = {
 	.arg1_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg2_type	= ARG_CONST_SIZE,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED,
+	.arg4_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_WRITE | MEM_ALIGNED,
 	.arg4_size	= sizeof(s64),
 };
 
@@ -561,7 +561,7 @@ const struct bpf_func_proto bpf_strtoul_proto = {
 	.arg1_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg2_type	= ARG_CONST_SIZE,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED,
+	.arg4_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_WRITE | MEM_ALIGNED,
 	.arg4_size	= sizeof(u64),
 };
 
@@ -1502,7 +1502,7 @@ static const struct bpf_func_proto bpf_dynptr_from_mem_proto = {
 	.arg1_type	= ARG_PTR_TO_UNINIT_MEM,
 	.arg2_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL | MEM_UNINIT,
+	.arg4_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL | MEM_UNINIT | MEM_WRITE,
 };
 
 BPF_CALL_5(bpf_dynptr_read, void *, dst, u32, len, struct bpf_dynptr_kern *, src,
diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index af75c54eb84f..095416e40df3 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -618,7 +618,7 @@ const struct bpf_func_proto bpf_ringbuf_reserve_dynptr_proto = {
 	.arg1_type	= ARG_CONST_MAP_PTR,
 	.arg2_type	= ARG_ANYTHING,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_RINGBUF | MEM_UNINIT,
+	.arg4_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_RINGBUF | MEM_UNINIT | MEM_WRITE,
 };
 
 BPF_CALL_2(bpf_ringbuf_submit_dynptr, struct bpf_dynptr_kern *, ptr, u64, flags)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 6455f80099cd..cfb361f4b00e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -5265,7 +5265,7 @@ static const struct bpf_func_proto bpf_kallsyms_lookup_name_proto = {
 	.arg1_type	= ARG_PTR_TO_MEM,
 	.arg2_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED,
+	.arg4_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_WRITE | MEM_ALIGNED,
 	.arg4_size	= sizeof(u64),
 };
 
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index e7b7be074e5a..f46903c1142b 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1192,7 +1192,7 @@ static const struct bpf_func_proto bpf_get_func_arg_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED,
+	.arg3_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_WRITE | MEM_ALIGNED,
 	.arg3_size	= sizeof(u64),
 };
 
@@ -1209,7 +1209,7 @@ static const struct bpf_func_proto bpf_get_func_ret_proto = {
 	.func		= get_func_ret,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED,
+	.arg2_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_WRITE | MEM_ALIGNED,
 	.arg2_size	= sizeof(u64),
 };
 
diff --git a/net/core/filter.c b/net/core/filter.c
index cf87e29a5e8f..7f9d703b00e7 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6243,7 +6243,7 @@ static const struct bpf_func_proto bpf_skb_check_mtu_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type      = ARG_PTR_TO_CTX,
 	.arg2_type      = ARG_ANYTHING,
-	.arg3_type      = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED,
+	.arg3_type      = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_WRITE | MEM_ALIGNED,
 	.arg3_size	= sizeof(u32),
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
@@ -6255,7 +6255,7 @@ static const struct bpf_func_proto bpf_xdp_check_mtu_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type      = ARG_PTR_TO_CTX,
 	.arg2_type      = ARG_ANYTHING,
-	.arg3_type      = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED,
+	.arg3_type      = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_WRITE | MEM_ALIGNED,
 	.arg3_size	= sizeof(u32),
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
-- 
2.43.0

[PATCH 6.1 2/2] bpf: Fix overloading of MEM_UNINIT's meaning

[hsimeliere.opensource]

From: Daniel Borkmann <daniel@iogearbox.net>

[ Upstream commit 8ea607330a39184f51737c6ae706db7fdca7628e ]

Lonial reported an issue in the BPF verifier where check_mem_size_reg()
has the following code:

    if (!tnum_is_const(reg->var_off))
        /* For unprivileged variable accesses, disable raw
         * mode so that the program is required to
         * initialize all the memory that the helper could
         * just partially fill up.
         */
         meta = NULL;

This means that writes are not checked when the register containing the
size of the passed buffer has not a fixed size. Through this bug, a BPF
program can write to a map which is marked as read-only, for example,
.rodata global maps.

The problem is that MEM_UNINIT's initial meaning that "the passed buffer
to the BPF helper does not need to be initialized" which was added back
in commit 435faee1aae9 ("bpf, verifier: add ARG_PTR_TO_RAW_STACK type")
got overloaded over time with "the passed buffer is being written to".

The problem however is that checks such as the above which were added later
via 06c1c049721a ("bpf: allow helpers access to variable memory") set meta
to NULL in order force the user to always initialize the passed buffer to
the helper. Due to the current double meaning of MEM_UNINIT, this bypasses
verifier write checks to the memory (not boundary checks though) and only
assumes the latter memory is read instead.

Fix this by reverting MEM_UNINIT back to its original meaning, and having
MEM_WRITE as an annotation to BPF helpers in order to then trigger the
BPF verifier checks for writing to memory.

Some notes: check_arg_pair_ok() ensures that for ARG_CONST_SIZE{,_OR_ZERO}
we can access fn->arg_type[arg - 1] since it must contain a preceding
ARG_PTR_TO_MEM. For check_mem_reg() the meta argument can be removed
altogether since we do check both BPF_READ and BPF_WRITE. Same for the
equivalent check_kfunc_mem_size_reg().

Fixes: 7b3552d3f9f6 ("bpf: Reject writes for PTR_TO_MAP_KEY in check_helper_mem_access")
Fixes: 97e6d7dab1ca ("bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access")
Fixes: 15baa55ff5b0 ("bpf/verifier: allow all functions to read user provided context")
Reported-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241021152809.33343-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: BRUNO VERNAY <bruno.vernay@se.com>
Signed-off-by: Hugo SIMELIERE <hsimeliere.opensource@witekio.com>
---
 kernel/bpf/verifier.c | 76 ++++++++++++++++++++-----------------------
 1 file changed, 36 insertions(+), 40 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bdd5105337dc..ead1811534a0 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5416,7 +5416,8 @@ static int check_stack_range_initialized(
 }
 
 static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
-				   int access_size, bool zero_size_allowed,
+				   int access_size, enum bpf_access_type access_type,
+				   bool zero_size_allowed,
 				   struct bpf_call_arg_meta *meta)
 {
 	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
@@ -5428,7 +5429,7 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 		return check_packet_access(env, regno, reg->off, access_size,
 					   zero_size_allowed);
 	case PTR_TO_MAP_KEY:
-		if (meta && meta->raw_mode) {
+		if (access_type == BPF_WRITE) {
 			verbose(env, "R%d cannot write into %s\n", regno,
 				reg_type_str(env, reg->type));
 			return -EACCES;
@@ -5436,15 +5437,13 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 		return check_mem_region_access(env, regno, reg->off, access_size,
 					       reg->map_ptr->key_size, false);
 	case PTR_TO_MAP_VALUE:
-		if (check_map_access_type(env, regno, reg->off, access_size,
-					  meta && meta->raw_mode ? BPF_WRITE :
-					  BPF_READ))
+		if (check_map_access_type(env, regno, reg->off, access_size, access_type))
 			return -EACCES;
 		return check_map_access(env, regno, reg->off, access_size,
 					zero_size_allowed, ACCESS_HELPER);
 	case PTR_TO_MEM:
 		if (type_is_rdonly_mem(reg->type)) {
-			if (meta && meta->raw_mode) {
+			if (access_type == BPF_WRITE) {
 				verbose(env, "R%d cannot write into %s\n", regno,
 					reg_type_str(env, reg->type));
 				return -EACCES;
@@ -5455,7 +5454,7 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 					       zero_size_allowed);
 	case PTR_TO_BUF:
 		if (type_is_rdonly_mem(reg->type)) {
-			if (meta && meta->raw_mode) {
+			if (access_type == BPF_WRITE) {
 				verbose(env, "R%d cannot write into %s\n", regno,
 					reg_type_str(env, reg->type));
 				return -EACCES;
@@ -5480,7 +5479,6 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 		 * Dynamically check it now.
 		 */
 		if (!env->ops->convert_ctx_access) {
-			enum bpf_access_type atype = meta && meta->raw_mode ? BPF_WRITE : BPF_READ;
 			int offset = access_size - 1;
 
 			/* Allow zero-byte read from PTR_TO_CTX */
@@ -5488,7 +5486,7 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 				return zero_size_allowed ? 0 : -EACCES;
 
 			return check_mem_access(env, env->insn_idx, regno, offset, BPF_B,
-						atype, -1, false);
+						access_type, -1, false);
 		}
 
 		fallthrough;
@@ -5507,6 +5505,7 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 
 static int check_mem_size_reg(struct bpf_verifier_env *env,
 			      struct bpf_reg_state *reg, u32 regno,
+			      enum bpf_access_type access_type,
 			      bool zero_size_allowed,
 			      struct bpf_call_arg_meta *meta)
 {
@@ -5522,15 +5521,12 @@ static int check_mem_size_reg(struct bpf_verifier_env *env,
 	 */
 	meta->msize_max_value = reg->umax_value;
 
-	/* The register is SCALAR_VALUE; the access check
-	 * happens using its boundaries.
+	/* The register is SCALAR_VALUE; the access check happens using
+	 * its boundaries. For unprivileged variable accesses, disable
+	 * raw mode so that the program is required to initialize all
+	 * the memory that the helper could just partially fill up.
 	 */
 	if (!tnum_is_const(reg->var_off))
-		/* For unprivileged variable accesses, disable raw
-		 * mode so that the program is required to
-		 * initialize all the memory that the helper could
-		 * just partially fill up.
-		 */
 		meta = NULL;
 
 	if (reg->smin_value < 0) {
@@ -5541,8 +5537,7 @@ static int check_mem_size_reg(struct bpf_verifier_env *env,
 
 	if (reg->umin_value == 0) {
 		err = check_helper_mem_access(env, regno - 1, 0,
-					      zero_size_allowed,
-					      meta);
+				      access_type, zero_size_allowed, meta);
 		if (err)
 			return err;
 	}
@@ -5552,9 +5547,8 @@ static int check_mem_size_reg(struct bpf_verifier_env *env,
 			regno);
 		return -EACCES;
 	}
-	err = check_helper_mem_access(env, regno - 1,
-				      reg->umax_value,
-				      zero_size_allowed, meta);
+	err = check_helper_mem_access(env, regno - 1, reg->umax_value,
+				      access_type, zero_size_allowed, meta);
 	if (!err)
 		err = mark_chain_precision(env, regno);
 	return err;
@@ -5565,13 +5559,11 @@ int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
 {
 	bool may_be_null = type_may_be_null(reg->type);
 	struct bpf_reg_state saved_reg;
-	struct bpf_call_arg_meta meta;
 	int err;
 
 	if (register_is_null(reg))
 		return 0;
 
-	memset(&meta, 0, sizeof(meta));
 	/* Assuming that the register contains a value check if the memory
 	 * access is safe. Temporarily save and restore the register's state as
 	 * the conversion shouldn't be visible to a caller.
@@ -5581,10 +5573,8 @@ int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
 		mark_ptr_not_null_reg(reg);
 	}
 
-	err = check_helper_mem_access(env, regno, mem_size, true, &meta);
-	/* Check access for BPF_WRITE */
-	meta.raw_mode = true;
-	err = err ?: check_helper_mem_access(env, regno, mem_size, true, &meta);
+	err = check_helper_mem_access(env, regno, mem_size, BPF_READ, true, NULL);
+	err = err ?: check_helper_mem_access(env, regno, mem_size, BPF_WRITE, true, NULL);
 
 	if (may_be_null)
 		*reg = saved_reg;
@@ -5610,13 +5600,12 @@ int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state
 		mark_ptr_not_null_reg(mem_reg);
 	}
 
-	err = check_mem_size_reg(env, reg, regno, true, &meta);
-	/* Check access for BPF_WRITE */
-	meta.raw_mode = true;
-	err = err ?: check_mem_size_reg(env, reg, regno, true, &meta);
+	err = check_mem_size_reg(env, reg, regno, BPF_READ, true, &meta);
+	err = err ?: check_mem_size_reg(env, reg, regno, BPF_WRITE, true, &meta);
 
 	if (may_be_null)
 		*mem_reg = saved_reg;
+
 	return err;
 }
 
@@ -6227,9 +6216,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 			verbose(env, "invalid map_ptr to access map->key\n");
 			return -EACCES;
 		}
-		err = check_helper_mem_access(env, regno,
-					      meta->map_ptr->key_size, false,
-					      NULL);
+		err = check_helper_mem_access(env, regno, meta->map_ptr->key_size,
+					      BPF_READ, false, NULL);
 		break;
 	case ARG_PTR_TO_MAP_VALUE:
 		if (type_may_be_null(arg_type) && register_is_null(reg))
@@ -6244,9 +6232,9 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 			return -EACCES;
 		}
 		meta->raw_mode = arg_type & MEM_UNINIT;
-		err = check_helper_mem_access(env, regno,
-					      meta->map_ptr->value_size, false,
-					      meta);
+		err = check_helper_mem_access(env, regno, meta->map_ptr->value_size,
+					      arg_type & MEM_WRITE ? BPF_WRITE : BPF_READ,
+					      false, meta);
 		break;
 	case ARG_PTR_TO_PERCPU_BTF_ID:
 		if (!reg->btf_id) {
@@ -6281,7 +6269,9 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		 */
 		meta->raw_mode = arg_type & MEM_UNINIT;
 		if (arg_type & MEM_FIXED_SIZE) {
-			err = check_helper_mem_access(env, regno, fn->arg_size[arg], false, meta);
+			err = check_helper_mem_access(env, regno, fn->arg_size[arg],
+						      arg_type & MEM_WRITE ? BPF_WRITE : BPF_READ,
+						      false, meta);
 			if (err)
 				return err;
 			if (arg_type & MEM_ALIGNED)
@@ -6289,10 +6279,16 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		}
 		break;
 	case ARG_CONST_SIZE:
-		err = check_mem_size_reg(env, reg, regno, false, meta);
+		err = check_mem_size_reg(env, reg, regno,
+					 fn->arg_type[arg - 1] & MEM_WRITE ?
+					 BPF_WRITE : BPF_READ,
+					 false, meta);
 		break;
 	case ARG_CONST_SIZE_OR_ZERO:
-		err = check_mem_size_reg(env, reg, regno, true, meta);
+		err = check_mem_size_reg(env, reg, regno,
+					 fn->arg_type[arg - 1] & MEM_WRITE ?
+					 BPF_WRITE : BPF_READ,
+					 true, meta);
 		break;
 	case ARG_PTR_TO_DYNPTR:
 		/* We only need to check for initialized / uninitialized helper
-- 
2.43.0

Re: [PATCH 6.1 1/2] bpf: Add MEM_WRITE attribute

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: 6fad274f06f038c29660aa53fbad14241c9fd976

WARNING: Author mismatch between patch and upstream commit:
Backport author: hsimeliere.opensource@witekio.com
Commit author: Daniel Borkmann<daniel@iogearbox.net>


Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.6.y | Present (different SHA1: 8a33a047bd31)
6.1.y | Not found

Note: The patch differs from the upstream commit:
---
1:  6fad274f06f0 ! 1:  c54a19e115f6 bpf: Add MEM_WRITE attribute
    @@ Metadata
      ## Commit message ##
         bpf: Add MEM_WRITE attribute
     
    +    [ Upstream commit 6fad274f06f038c29660aa53fbad14241c9fd976 ]
    +
         Add a MEM_WRITE attribute for BPF helper functions which can be used in
         bpf_func_proto to annotate an argument type in order to let the verifier
         know that the helper writes into the memory passed as an argument. In
    @@ Commit message
         Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
         Link: https://lore.kernel.org/r/20241021152809.33343-1-daniel@iogearbox.net
         Signed-off-by: Alexei Starovoitov <ast@kernel.org>
    +    Signed-off-by: BRUNO VERNAY <bruno.vernay@se.com>
    +    Signed-off-by: Hugo SIMELIERE <hsimeliere.opensource@witekio.com>
     
      ## include/linux/bpf.h ##
     @@ include/linux/bpf.h: enum bpf_type_flag {
    @@ include/linux/bpf.h: enum bpf_type_flag {
      	__BPF_TYPE_LAST_FLAG	= __BPF_TYPE_FLAG_MAX - 1,
      };
     @@ include/linux/bpf.h: enum bpf_arg_type {
    - 	ARG_PTR_TO_SOCKET_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_SOCKET,
    + 	ARG_PTR_TO_ALLOC_MEM_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_ALLOC_MEM,
      	ARG_PTR_TO_STACK_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_STACK,
      	ARG_PTR_TO_BTF_ID_OR_NULL	= PTR_MAYBE_NULL | ARG_PTR_TO_BTF_ID,
     -	/* pointer to memory does not need to be initialized, helper function must fill
    @@ kernel/bpf/helpers.c: static const struct bpf_func_proto bpf_dynptr_from_mem_pro
     +	.arg4_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL | MEM_UNINIT | MEM_WRITE,
      };
      
    - BPF_CALL_5(bpf_dynptr_read, void *, dst, u32, len, const struct bpf_dynptr_kern *, src,
    + BPF_CALL_5(bpf_dynptr_read, void *, dst, u32, len, struct bpf_dynptr_kern *, src,
     
      ## kernel/bpf/ringbuf.c ##
     @@ kernel/bpf/ringbuf.c: const struct bpf_func_proto bpf_ringbuf_reserve_dynptr_proto = {
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |

Re: [PATCH 6.1 2/2] bpf: Fix overloading of MEM_UNINIT's meaning

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: 8ea607330a39184f51737c6ae706db7fdca7628e

WARNING: Author mismatch between patch and upstream commit:
Backport author: hsimeliere.opensource@witekio.com
Commit author: Daniel Borkmann<daniel@iogearbox.net>


Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.6.y | Present (different SHA1: 48068ccaea95)
6.1.y | Not found

Note: The patch differs from the upstream commit:
---
1:  8ea607330a39 ! 1:  2a7a87725633 bpf: Fix overloading of MEM_UNINIT's meaning
    @@ Metadata
      ## Commit message ##
         bpf: Fix overloading of MEM_UNINIT's meaning
     
    +    [ Upstream commit 8ea607330a39184f51737c6ae706db7fdca7628e ]
    +
         Lonial reported an issue in the BPF verifier where check_mem_size_reg()
         has the following code:
     
    @@ Commit message
         Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
         Link: https://lore.kernel.org/r/20241021152809.33343-2-daniel@iogearbox.net
         Signed-off-by: Alexei Starovoitov <ast@kernel.org>
    +    Signed-off-by: BRUNO VERNAY <bruno.vernay@se.com>
    +    Signed-off-by: Hugo SIMELIERE <hsimeliere.opensource@witekio.com>
     
      ## kernel/bpf/verifier.c ##
     @@ kernel/bpf/verifier.c: static int check_stack_range_initialized(
    @@ kernel/bpf/verifier.c: static int check_helper_mem_access(struct bpf_verifier_en
      				return zero_size_allowed ? 0 : -EACCES;
      
      			return check_mem_access(env, env->insn_idx, regno, offset, BPF_B,
    --						atype, -1, false, false);
    -+						access_type, -1, false, false);
    +-						atype, -1, false);
    ++						access_type, -1, false);
      		}
      
      		fallthrough;
     @@ kernel/bpf/verifier.c: static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
    -  */
    + 
      static int check_mem_size_reg(struct bpf_verifier_env *env,
      			      struct bpf_reg_state *reg, u32 regno,
     +			      enum bpf_access_type access_type,
    @@ kernel/bpf/verifier.c: static int check_mem_size_reg(struct bpf_verifier_env *en
      
      	if (reg->smin_value < 0) {
     @@ kernel/bpf/verifier.c: static int check_mem_size_reg(struct bpf_verifier_env *env,
    + 
    + 	if (reg->umin_value == 0) {
    + 		err = check_helper_mem_access(env, regno - 1, 0,
    +-					      zero_size_allowed,
    +-					      meta);
    ++				      access_type, zero_size_allowed, meta);
    + 		if (err)
    + 			return err;
    + 	}
    +@@ kernel/bpf/verifier.c: static int check_mem_size_reg(struct bpf_verifier_env *env,
      			regno);
      		return -EACCES;
      	}
    @@ kernel/bpf/verifier.c: static int check_mem_size_reg(struct bpf_verifier_env *en
      	if (!err)
      		err = mark_chain_precision(env, regno);
      	return err;
    -@@ kernel/bpf/verifier.c: static int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg
    +@@ kernel/bpf/verifier.c: int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
      {
      	bool may_be_null = type_may_be_null(reg->type);
      	struct bpf_reg_state saved_reg;
    @@ kernel/bpf/verifier.c: static int check_mem_reg(struct bpf_verifier_env *env, st
      	/* Assuming that the register contains a value check if the memory
      	 * access is safe. Temporarily save and restore the register's state as
      	 * the conversion shouldn't be visible to a caller.
    -@@ kernel/bpf/verifier.c: static int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg
    +@@ kernel/bpf/verifier.c: int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
      		mark_ptr_not_null_reg(reg);
      	}
      
    @@ kernel/bpf/verifier.c: static int check_mem_reg(struct bpf_verifier_env *env, st
      
      	if (may_be_null)
      		*reg = saved_reg;
    -@@ kernel/bpf/verifier.c: static int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg
    +@@ kernel/bpf/verifier.c: int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state
      		mark_ptr_not_null_reg(mem_reg);
      	}
      
    @@ kernel/bpf/verifier.c: static int check_func_arg(struct bpf_verifier_env *env, u
     +					 true, meta);
      		break;
      	case ARG_PTR_TO_DYNPTR:
    - 		err = process_dynptr_func(env, regno, insn_idx, arg_type, 0);
    + 		/* We only need to check for initialized / uninitialized helper
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |