bpf: Fix memory access flags in helper prototypes

[ Upstream commit 802eef5afb1865bc5536a5302c068ba2215a1f72 ]

After commit 37cce22dbd51 ("bpf: verifier: Refactor helper access type tracking"),
the verifier started relying on the access type flags in helper
function prototypes to perform memory access optimizations.

Currently, several helper functions utilizing ARG_PTR_TO_MEM lack the
corresponding MEM_RDONLY or MEM_WRITE flags. This omission causes the
verifier to incorrectly assume that the buffer contents are unchanged
across the helper call. Consequently, the verifier may optimize away
subsequent reads based on this wrong assumption, leading to correctness
issues.

For bpf_get_stack_proto_raw_tp, the original MEM_RDONLY was incorrect
since the helper writes to the buffer. Change it to ARG_PTR_TO_UNINIT_MEM
which correctly indicates write access to potentially uninitialized memory.

Similar issues were recently addressed for specific helpers in commit
ac44dcc788b9 ("bpf: Fix verifier assumptions of bpf_d_path's output buffer")
and commit 2eb7648558a7 ("bpf: Specify access type of bpf_sysctl_get_name args").

Fix these prototypes by adding the correct memory access flags.

Fixes: 37cce22dbd51 ("bpf: verifier: Refactor helper access type tracking")
Co-developed-by: Shuran Liu <electronlsr@gmail.com>
Signed-off-by: Shuran Liu <electronlsr@gmail.com>
Co-developed-by: Peili Gao <gplhust955@gmail.com>
Signed-off-by: Peili Gao <gplhust955@gmail.com>
Co-developed-by: Haoran Ni <haoran.ni.cs@gmail.com>
Signed-off-by: Haoran Ni <haoran.ni.cs@gmail.com>
Signed-off-by: Zesen Liu <ftyghome@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260120-helper_proto-v3-1-27b0180b4e77@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 10 insertions, 10 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index 029e560e32ce..b1f8e2930e1c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6401,7 +6401,7 @@ static const struct bpf_func_proto bpf_xdp_fib_lookup_proto = {
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type      = ARG_PTR_TO_CTX,
-	.arg2_type      = ARG_PTR_TO_MEM,
+	.arg2_type      = ARG_PTR_TO_MEM | MEM_WRITE,
 	.arg3_type      = ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 };
@@ -6456,7 +6456,7 @@ static const struct bpf_func_proto bpf_skb_fib_lookup_proto = {
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type      = ARG_PTR_TO_CTX,
-	.arg2_type      = ARG_PTR_TO_MEM,
+	.arg2_type      = ARG_PTR_TO_MEM | MEM_WRITE,
 	.arg3_type      = ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 };
@@ -8010,9 +8010,9 @@ static const struct bpf_func_proto bpf_tcp_raw_gen_syncookie_ipv4_proto = {
 	.gpl_only	= true, /* __cookie_v4_init_sequence() is GPL */
 	.pkt_access	= true,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_FIXED_SIZE_MEM,
+	.arg1_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_RDONLY,
 	.arg1_size	= sizeof(struct iphdr),
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -8042,9 +8042,9 @@ static const struct bpf_func_proto bpf_tcp_raw_gen_syncookie_ipv6_proto = {
 	.gpl_only	= true, /* __cookie_v6_init_sequence() is GPL */
 	.pkt_access	= true,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_FIXED_SIZE_MEM,
+	.arg1_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_RDONLY,
 	.arg1_size	= sizeof(struct ipv6hdr),
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -8062,9 +8062,9 @@ static const struct bpf_func_proto bpf_tcp_raw_check_syncookie_ipv4_proto = {
 	.gpl_only	= true, /* __cookie_v4_check is GPL */
 	.pkt_access	= true,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_FIXED_SIZE_MEM,
+	.arg1_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_RDONLY,
 	.arg1_size	= sizeof(struct iphdr),
-	.arg2_type	= ARG_PTR_TO_FIXED_SIZE_MEM,
+	.arg2_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_RDONLY,
 	.arg2_size	= sizeof(struct tcphdr),
 };
 
@@ -8086,9 +8086,9 @@ static const struct bpf_func_proto bpf_tcp_raw_check_syncookie_ipv6_proto = {
 	.gpl_only	= true, /* __cookie_v6_check is GPL */
 	.pkt_access	= true,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_FIXED_SIZE_MEM,
+	.arg1_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_RDONLY,
 	.arg1_size	= sizeof(struct ipv6hdr),
-	.arg2_type	= ARG_PTR_TO_FIXED_SIZE_MEM,
+	.arg2_type	= ARG_PTR_TO_FIXED_SIZE_MEM | MEM_RDONLY,
 	.arg2_size	= sizeof(struct tcphdr),
 };
 #endif /* CONFIG_SYN_COOKIES */