6 files changed, 50 insertions, 8 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 2934249fba46..5e2a4a391ba9 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1392,6 +1392,13 @@ config BPF_SYSCALL
           Enable the bpf() system call that allows to manipulate eBPF
           programs and maps via file descriptors.
 
+config BPF_JIT_ALWAYS_ON
+        bool "Permanently enable BPF JIT and remove BPF interpreter"
+        depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
+        help
+          Enables BPF JIT and removes BPF interpreter to avoid
+          speculative execution of BPF instructions by the interpreter
+
 config USERFAULTFD
         bool "Enable userfaultfd() system call"
         select ANON_INODES
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 86b50aa26ee8..51ec2dda7f08 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -767,6 +767,7 @@ noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 }
 EXPORT_SYMBOL_GPL(__bpf_call_base);
 
+#ifndef CONFIG_BPF_JIT_ALWAYS_ON
 /**
  *      __bpf_prog_run - run eBPF program on a given context
  *      @ctx: is the data we are operating on
@@ -1317,6 +1318,14 @@ EVAL6(PROG_NAME_LIST, 224, 256, 288, 320, 352, 384)
 EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
 };
 
+#else
+static unsigned int __bpf_prog_ret0(const void *ctx,
+                                    const struct bpf_insn *insn)
+{
+        return 0;
+}
+#endif
+
 bool bpf_prog_array_compatible(struct bpf_array *array,
                                const struct bpf_prog *fp)
 {
@@ -1364,9 +1373,13 @@ static int bpf_check_tail_call(const struct bpf_prog *fp)
  */
 struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
 {
+#ifndef CONFIG_BPF_JIT_ALWAYS_ON
         u32 stack_depth = max_t(u32, fp->aux->stack_depth, 1);
 
         fp->bpf_func = interpreters[(round_up(stack_depth, 32) / 32) - 1];
+#else
+        fp->bpf_func = __bpf_prog_ret0;
+#endif
 
         /* eBPF JITs can rewrite the program in case constant
          * blinding is active. However, in case of error during
@@ -1376,6 +1389,12 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
          */
         if (!bpf_prog_is_dev_bound(fp->aux)) {
                 fp = bpf_int_jit_compile(fp);
+#ifdef CONFIG_BPF_JIT_ALWAYS_ON
+                if (!fp->jited) {
+                        *err = -ENOTSUPP;
+                        return fp;
+                }
+#endif
         } else {
                 *err = bpf_prog_offload_compile(fp);
                 if (*err)
diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 9e9748089270..f369889e521d 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -6250,9 +6250,8 @@ static struct bpf_prog *generate_filter(int which, int *err)
                                 return NULL;
                         }
                 }
-                /* We don't expect to fail. */
                 if (*err) {
-                        pr_cont("FAIL to attach err=%d len=%d\n",
+                        pr_cont("FAIL to prog_create err=%d len=%d\n",
                                 *err, fprog.len);
                         return NULL;
                 }
@@ -6276,6 +6275,10 @@ static struct bpf_prog *generate_filter(int which, int *err)
                  * checks.
                  */
                 fp = bpf_prog_select_runtime(fp, err);
+                if (*err) {
+                        pr_cont("FAIL to select_runtime err=%d\n", *err);
+                        return NULL;
+                }
                 break;
         }
 
@@ -6461,8 +6464,8 @@ static __init int test_bpf(void)
                                 pass_cnt++;
                                 continue;
                         }
-
-                        return err;
+                        err_cnt++;
+                        continue;
                 }
 
                 pr_cont("jited:%u ", fp->jited);
diff --git a/net/core/filter.c b/net/core/filter.c
index 6a85e67fafce..d339ef170df6 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1054,11 +1054,9 @@ static struct bpf_prog *bpf_migrate_filter(struct bpf_prog *fp)
                  */
                 goto out_err_free;
 
-        /* We are guaranteed to never error here with cBPF to eBPF
-         * transitions, since there's no issue with type compatibility
-         * checks on program arrays.
-         */
         fp = bpf_prog_select_runtime(fp, &err);
+        if (err)
+                goto out_err_free;
 
         kfree(old_prog);
         return fp;
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index cbc3dde4cfcc..a47ad6cd41c0 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -325,7 +325,13 @@ static struct ctl_table net_core_table[] = {
                 .data           = &bpf_jit_enable,
                 .maxlen         = sizeof(int),
                 .mode           = 0644,
+#ifndef CONFIG_BPF_JIT_ALWAYS_ON
                 .proc_handler   = proc_dointvec
+#else
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &one,
+                .extra2         = &one,
+#endif
         },
 # ifdef CONFIG_HAVE_EBPF_JIT
         {
diff --git a/net/socket.c b/net/socket.c
index 05f361faec45..78acd6ce74c7 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2619,6 +2619,15 @@ out_fs:
 
 core_initcall(sock_init);       /* early initcall */
 
+static int __init jit_init(void)
+{
+#ifdef CONFIG_BPF_JIT_ALWAYS_ON
+        bpf_jit_enable = 1;
+#endif
+        return 0;
+}
+pure_initcall(jit_init);
+
 #ifdef CONFIG_PROC_FS
 void socket_seq_show(struct seq_file *seq)
 {