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-rw-r--r--kernel/bpf/bpf_lsm.c23
-rw-r--r--kernel/bpf/btf.c16
-rw-r--r--kernel/bpf/syscall.c57
-rw-r--r--kernel/bpf/trampoline.c17
-rw-r--r--kernel/bpf/verifier.c19
5 files changed, 105 insertions, 27 deletions
diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c
index 3b3bbb28603e..19636703b24e 100644
--- a/kernel/bpf/bpf_lsm.c
+++ b/kernel/bpf/bpf_lsm.c
@@ -9,6 +9,8 @@
#include <linux/btf.h>
#include <linux/lsm_hooks.h>
#include <linux/bpf_lsm.h>
+#include <linux/kallsyms.h>
+#include <linux/bpf_verifier.h>
/* For every LSM hook that allows attachment of BPF programs, declare a nop
* function where a BPF program can be attached.
@@ -22,6 +24,27 @@ noinline RET bpf_lsm_##NAME(__VA_ARGS__) \
#include <linux/lsm_hook_defs.h>
#undef LSM_HOOK
+#define BPF_LSM_SYM_PREFX "bpf_lsm_"
+
+int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
+ const struct bpf_prog *prog)
+{
+ if (!prog->gpl_compatible) {
+ bpf_log(vlog,
+ "LSM programs must have a GPL compatible license\n");
+ return -EINVAL;
+ }
+
+ if (strncmp(BPF_LSM_SYM_PREFX, prog->aux->attach_func_name,
+ sizeof(BPF_LSM_SYM_PREFX) - 1)) {
+ bpf_log(vlog, "attach_btf_id %u points to wrong type name %s\n",
+ prog->aux->attach_btf_id, prog->aux->attach_func_name);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
const struct bpf_prog_ops lsm_prog_ops = {
};
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 6f397c4da05e..de335cd386f0 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3710,7 +3710,21 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
}
if (arg == nr_args) {
- if (prog->expected_attach_type == BPF_TRACE_FEXIT) {
+ if (prog->expected_attach_type == BPF_TRACE_FEXIT ||
+ prog->expected_attach_type == BPF_LSM_MAC) {
+ /* When LSM programs are attached to void LSM hooks
+ * they use FEXIT trampolines and when attached to
+ * int LSM hooks, they use MODIFY_RETURN trampolines.
+ *
+ * While the LSM programs are BPF_MODIFY_RETURN-like
+ * the check:
+ *
+ * if (ret_type != 'int')
+ * return -EINVAL;
+ *
+ * is _not_ done here. This is still safe as LSM hooks
+ * have only void and int return types.
+ */
if (!t)
return true;
t = btf_type_by_id(btf, t->type);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index b2584b25748c..a616b63f23b4 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -25,6 +25,7 @@
#include <linux/nospec.h>
#include <linux/audit.h>
#include <uapi/linux/btf.h>
+#include <linux/bpf_lsm.h>
#define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
(map)->map_type == BPF_MAP_TYPE_CGROUP_ARRAY || \
@@ -1935,6 +1936,7 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
switch (prog_type) {
case BPF_PROG_TYPE_TRACING:
+ case BPF_PROG_TYPE_LSM:
case BPF_PROG_TYPE_STRUCT_OPS:
case BPF_PROG_TYPE_EXT:
break;
@@ -2366,10 +2368,28 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog)
struct file *link_file;
int link_fd, err;
- if (prog->expected_attach_type != BPF_TRACE_FENTRY &&
- prog->expected_attach_type != BPF_TRACE_FEXIT &&
- prog->expected_attach_type != BPF_MODIFY_RETURN &&
- prog->type != BPF_PROG_TYPE_EXT) {
+ switch (prog->type) {
+ case BPF_PROG_TYPE_TRACING:
+ if (prog->expected_attach_type != BPF_TRACE_FENTRY &&
+ prog->expected_attach_type != BPF_TRACE_FEXIT &&
+ prog->expected_attach_type != BPF_MODIFY_RETURN) {
+ err = -EINVAL;
+ goto out_put_prog;
+ }
+ break;
+ case BPF_PROG_TYPE_EXT:
+ if (prog->expected_attach_type != 0) {
+ err = -EINVAL;
+ goto out_put_prog;
+ }
+ break;
+ case BPF_PROG_TYPE_LSM:
+ if (prog->expected_attach_type != BPF_LSM_MAC) {
+ err = -EINVAL;
+ goto out_put_prog;
+ }
+ break;
+ default:
err = -EINVAL;
goto out_put_prog;
}
@@ -2448,16 +2468,10 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
if (IS_ERR(prog))
return PTR_ERR(prog);
- if (prog->type != BPF_PROG_TYPE_RAW_TRACEPOINT &&
- prog->type != BPF_PROG_TYPE_TRACING &&
- prog->type != BPF_PROG_TYPE_EXT &&
- prog->type != BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE) {
- err = -EINVAL;
- goto out_put_prog;
- }
-
- if (prog->type == BPF_PROG_TYPE_TRACING ||
- prog->type == BPF_PROG_TYPE_EXT) {
+ switch (prog->type) {
+ case BPF_PROG_TYPE_TRACING:
+ case BPF_PROG_TYPE_EXT:
+ case BPF_PROG_TYPE_LSM:
if (attr->raw_tracepoint.name) {
/* The attach point for this category of programs
* should be specified via btf_id during program load.
@@ -2465,11 +2479,14 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
err = -EINVAL;
goto out_put_prog;
}
- if (prog->expected_attach_type == BPF_TRACE_RAW_TP)
+ if (prog->type == BPF_PROG_TYPE_TRACING &&
+ prog->expected_attach_type == BPF_TRACE_RAW_TP) {
tp_name = prog->aux->attach_func_name;
- else
- return bpf_tracing_prog_attach(prog);
- } else {
+ break;
+ }
+ return bpf_tracing_prog_attach(prog);
+ case BPF_PROG_TYPE_RAW_TRACEPOINT:
+ case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
if (strncpy_from_user(buf,
u64_to_user_ptr(attr->raw_tracepoint.name),
sizeof(buf) - 1) < 0) {
@@ -2478,6 +2495,10 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
}
buf[sizeof(buf) - 1] = 0;
tp_name = buf;
+ break;
+ default:
+ err = -EINVAL;
+ goto out_put_prog;
}
btp = bpf_get_raw_tracepoint(tp_name);
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index f30bca2a4d01..9be85aa4ec5f 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -6,6 +6,7 @@
#include <linux/ftrace.h>
#include <linux/rbtree_latch.h>
#include <linux/perf_event.h>
+#include <linux/btf.h>
/* dummy _ops. The verifier will operate on target program's ops. */
const struct bpf_verifier_ops bpf_extension_verifier_ops = {
@@ -233,15 +234,23 @@ out:
return err;
}
-static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(enum bpf_attach_type t)
+static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog)
{
- switch (t) {
+ switch (prog->expected_attach_type) {
case BPF_TRACE_FENTRY:
return BPF_TRAMP_FENTRY;
case BPF_MODIFY_RETURN:
return BPF_TRAMP_MODIFY_RETURN;
case BPF_TRACE_FEXIT:
return BPF_TRAMP_FEXIT;
+ case BPF_LSM_MAC:
+ if (!prog->aux->attach_func_proto->type)
+ /* The function returns void, we cannot modify its
+ * return value.
+ */
+ return BPF_TRAMP_FEXIT;
+ else
+ return BPF_TRAMP_MODIFY_RETURN;
default:
return BPF_TRAMP_REPLACE;
}
@@ -255,7 +264,7 @@ int bpf_trampoline_link_prog(struct bpf_prog *prog)
int cnt;
tr = prog->aux->trampoline;
- kind = bpf_attach_type_to_tramp(prog->expected_attach_type);
+ kind = bpf_attach_type_to_tramp(prog);
mutex_lock(&tr->mutex);
if (tr->extension_prog) {
/* cannot attach fentry/fexit if extension prog is attached.
@@ -305,7 +314,7 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog)
int err;
tr = prog->aux->trampoline;
- kind = bpf_attach_type_to_tramp(prog->expected_attach_type);
+ kind = bpf_attach_type_to_tramp(prog);
mutex_lock(&tr->mutex);
if (kind == BPF_TRAMP_REPLACE) {
WARN_ON_ONCE(!tr->extension_prog);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 46ba86c540e2..047b2e876399 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -20,6 +20,7 @@
#include <linux/perf_event.h>
#include <linux/ctype.h>
#include <linux/error-injection.h>
+#include <linux/bpf_lsm.h>
#include "disasm.h"
@@ -6492,8 +6493,9 @@ static int check_return_code(struct bpf_verifier_env *env)
struct tnum range = tnum_range(0, 1);
int err;
- /* The struct_ops func-ptr's return type could be "void" */
- if (env->prog->type == BPF_PROG_TYPE_STRUCT_OPS &&
+ /* LSM and struct_ops func-ptr's return type could be "void" */
+ if ((env->prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
+ env->prog->type == BPF_PROG_TYPE_LSM) &&
!prog->aux->attach_func_proto->type)
return 0;
@@ -9923,7 +9925,9 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
if (prog->type == BPF_PROG_TYPE_STRUCT_OPS)
return check_struct_ops_btf_id(env);
- if (prog->type != BPF_PROG_TYPE_TRACING && !prog_extension)
+ if (prog->type != BPF_PROG_TYPE_TRACING &&
+ prog->type != BPF_PROG_TYPE_LSM &&
+ !prog_extension)
return 0;
if (!btf_id) {
@@ -10054,8 +10058,16 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
return -EINVAL;
/* fallthrough */
case BPF_MODIFY_RETURN:
+ case BPF_LSM_MAC:
case BPF_TRACE_FENTRY:
case BPF_TRACE_FEXIT:
+ prog->aux->attach_func_name = tname;
+ if (prog->type == BPF_PROG_TYPE_LSM) {
+ ret = bpf_lsm_verify_prog(&env->log, prog);
+ if (ret < 0)
+ return ret;
+ }
+
if (!btf_type_is_func(t)) {
verbose(env, "attach_btf_id %u is not a function\n",
btf_id);
@@ -10070,7 +10082,6 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
tr = bpf_trampoline_lookup(key);
if (!tr)
return -ENOMEM;
- prog->aux->attach_func_name = tname;
/* t is either vmlinux type or another program's type */
prog->aux->attach_func_proto = t;
mutex_lock(&tr->mutex);
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-24 14:47:25 +0000