| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20260115112246.221082-5-dongml2@chinatelecom.cn>
Date: Thu, 15 Jan 2026 19:22:38 +0800
From: Menglong Dong <menglong8.dong@...il.com>
To: ast@...nel.org,
andrii@...nel.org
Cc: daniel@...earbox.net,
martin.lau@...ux.dev,
eddyz87@...il.com,
song@...nel.org,
yonghong.song@...ux.dev,
john.fastabend@...il.com,
kpsingh@...nel.org,
sdf@...ichev.me,
haoluo@...gle.com,
jolsa@...nel.org,
davem@...emloft.net,
dsahern@...nel.org,
tglx@...utronix.de,
mingo@...hat.com,
jiang.biao@...ux.dev,
bp@...en8.de,
dave.hansen@...ux.intel.com,
x86@...nel.org,
hpa@...or.com,
bpf@...r.kernel.org,
netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next v10 04/12] bpf: support fsession for bpf_session_is_return
If fsession exists, we will use the bit (1 << BPF_TRAMP_SHIFT_IS_RETURN)
in ((u64 *)ctx)[-1] to store the "is_return" flag.
The logic of bpf_session_is_return() for fsession is implemented in the
verifier by inline following code:
bool bpf_session_is_return(void *ctx)
{
return (((u64 *)ctx)[-1] >> BPF_TRAMP_SHIFT_IS_RETURN) & 1;
}
Signed-off-by: Menglong Dong <dongml2@...natelecom.cn>
Co-developed-by: Leon Hwang <leon.hwang@...ux.dev>
Signed-off-by: Leon Hwang <leon.hwang@...ux.dev>
---
v10:
- fix the wrong description of bpf_session_is_return() in commit log and
comment
- rename the prefix from BPF_TRAMP_M_ tp BPF_TRAMP_SHIFT_
- remove the definition of BPF_TRAMP_M_NR_ARGS
- use 63 for the shift of BPF_TRAMP_SHIFT_IS_RETURN
- check the program type in bpf_session_filter()
v9:
- remove the definition of bpf_fsession_is_return()
v7:
- reuse the kfunc bpf_session_is_return() instead of introduce new kfunc
v4:
- split out the bpf_fsession_cookie() to another patch
v3:
- merge the bpf_tracing_is_exit and bpf_fsession_cookie into a single
patch
v2:
- store the session flags after return value, instead of before nr_args
- inline the bpf_tracing_is_exit, as Jiri suggested
---
include/linux/bpf.h | 2 ++
kernel/bpf/verifier.c | 13 +++++++++++++
kernel/trace/bpf_trace.c | 39 ++++++++++++++++++++++++++-------------
3 files changed, 41 insertions(+), 13 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 41228b0add52..4f72d553f52b 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1229,6 +1229,8 @@ enum {
#endif
};
+#define BPF_TRAMP_SHIFT_IS_RETURN 63
+
struct bpf_tramp_links {
struct bpf_tramp_link *links[BPF_MAX_TRAMP_LINKS];
int nr_links;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1ed41ba8b54c..2efe458f9bad 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -22604,6 +22604,19 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
desc->func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1);
*cnt = 1;
+ } else if (desc->func_id == special_kfunc_list[KF_bpf_session_is_return] &&
+ env->prog->expected_attach_type == BPF_TRACE_FSESSION) {
+ /*
+ * inline the bpf_session_is_return() for fsession:
+ * bool bpf_session_is_return(void *ctx)
+ * {
+ * return (((u64 *)ctx)[-1] >> BPF_TRAMP_SHIFT_IS_RETURN) & 1;
+ * }
+ */
+ insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
+ insn_buf[1] = BPF_ALU64_IMM(BPF_RSH, BPF_REG_0, BPF_TRAMP_SHIFT_IS_RETURN);
+ insn_buf[2] = BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 1);
+ *cnt = 3;
}
if (env->insn_aux_data[insn_idx].arg_prog) {
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 297dcafb2c55..3f5460a6da47 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1286,7 +1286,8 @@ static bool is_kprobe_multi(const struct bpf_prog *prog)
static inline bool is_kprobe_session(const struct bpf_prog *prog)
{
- return prog->expected_attach_type == BPF_TRACE_KPROBE_SESSION;
+ return prog->type == BPF_PROG_TYPE_KPROBE &&
+ prog->expected_attach_type == BPF_TRACE_KPROBE_SESSION;
}
static inline bool is_uprobe_multi(const struct bpf_prog *prog)
@@ -1297,7 +1298,14 @@ static inline bool is_uprobe_multi(const struct bpf_prog *prog)
static inline bool is_uprobe_session(const struct bpf_prog *prog)
{
- return prog->expected_attach_type == BPF_TRACE_UPROBE_SESSION;
+ return prog->type == BPF_PROG_TYPE_KPROBE &&
+ prog->expected_attach_type == BPF_TRACE_UPROBE_SESSION;
+}
+
+static inline bool is_trace_fsession(const struct bpf_prog *prog)
+{
+ return prog->type == BPF_PROG_TYPE_TRACING &&
+ prog->expected_attach_type == BPF_TRACE_FSESSION;
}
static const struct bpf_func_proto *
@@ -3334,34 +3342,39 @@ __bpf_kfunc __u64 *bpf_session_cookie(void *ctx)
__bpf_kfunc_end_defs();
-BTF_KFUNCS_START(kprobe_multi_kfunc_set_ids)
+BTF_KFUNCS_START(session_kfunc_set_ids)
BTF_ID_FLAGS(func, bpf_session_is_return)
BTF_ID_FLAGS(func, bpf_session_cookie)
-BTF_KFUNCS_END(kprobe_multi_kfunc_set_ids)
+BTF_KFUNCS_END(session_kfunc_set_ids)
-static int bpf_kprobe_multi_filter(const struct bpf_prog *prog, u32 kfunc_id)
+static int bpf_session_filter(const struct bpf_prog *prog, u32 kfunc_id)
{
- if (!btf_id_set8_contains(&kprobe_multi_kfunc_set_ids, kfunc_id))
+ if (!btf_id_set8_contains(&session_kfunc_set_ids, kfunc_id))
return 0;
- if (!is_kprobe_session(prog) && !is_uprobe_session(prog))
+ if (!is_kprobe_session(prog) && !is_uprobe_session(prog) && !is_trace_fsession(prog))
return -EACCES;
return 0;
}
-static const struct btf_kfunc_id_set bpf_kprobe_multi_kfunc_set = {
+static const struct btf_kfunc_id_set bpf_session_kfunc_set = {
.owner = THIS_MODULE,
- .set = &kprobe_multi_kfunc_set_ids,
- .filter = bpf_kprobe_multi_filter,
+ .set = &session_kfunc_set_ids,
+ .filter = bpf_session_filter,
};
-static int __init bpf_kprobe_multi_kfuncs_init(void)
+static int __init bpf_trace_kfuncs_init(void)
{
- return register_btf_kfunc_id_set(BPF_PROG_TYPE_KPROBE, &bpf_kprobe_multi_kfunc_set);
+ int err = 0;
+
+ err = err ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_KPROBE, &bpf_session_kfunc_set);
+ err = err ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_session_kfunc_set);
+
+ return err;
}
-late_initcall(bpf_kprobe_multi_kfuncs_init);
+late_initcall(bpf_trace_kfuncs_init);
typedef int (*copy_fn_t)(void *dst, const void *src, u32 size, struct task_struct *tsk);
--
2.52.0
Powered by blists - more mailing lists