From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
commit fa9dd599b4dae841924b022768354cfde9affecb upstream.
Having a pure_initcall() callback just to permanently enable BPF
JITs under CONFIG_BPF_JIT_ALWAYS_ON is unnecessary and could leave
a small race window in future where JIT is still disabled on boot.
Since we know about the setting at compilation time anyway, just
initialize it properly there. Also consolidate all the individual
bpf_jit_enable variables into a single one and move them under one
location. Moreover, don't allow for setting unspecified garbage
values on them.
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
[bwh: Backported to 4.14 as dependency of commit 2e4a30983b0f
"bpf: restrict access to core bpf sysctls":
- Adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
---
arch/arm/net/bpf_jit_32.c | 2 --
arch/arm64/net/bpf_jit_comp.c | 2 --
arch/mips/net/bpf_jit.c | 2 --
arch/mips/net/ebpf_jit.c | 2 --
arch/powerpc/net/bpf_jit_comp.c | 2 --
arch/powerpc/net/bpf_jit_comp64.c | 2 --
arch/s390/net/bpf_jit_comp.c | 2 --
arch/sparc/net/bpf_jit_comp_32.c | 2 --
arch/sparc/net/bpf_jit_comp_64.c | 2 --
arch/x86/net/bpf_jit_comp.c | 2 --
kernel/bpf/core.c | 19 ++++++++++++-------
net/core/sysctl_net_core.c | 18 ++++++++++++------
net/socket.c | 9 ---------
13 files changed, 24 insertions(+), 42 deletions(-)
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index dafeb5f81353..b18fb70c5dcf 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -25,8 +25,6 @@
#include "bpf_jit_32.h"
-int bpf_jit_enable __read_mostly;
-
/*
* eBPF prog stack layout:
*
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index b742171bfef7..1bbb457c293f 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -31,8 +31,6 @@
#include "bpf_jit.h"
-int bpf_jit_enable __read_mostly;
-
#define TMP_REG_1 (MAX_BPF_JIT_REG + 0)
#define TMP_REG_2 (MAX_BPF_JIT_REG + 1)
#define TCALL_CNT (MAX_BPF_JIT_REG + 2)
diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
index 44b925005dd3..4d8cb9bb8365 100644
--- a/arch/mips/net/bpf_jit.c
+++ b/arch/mips/net/bpf_jit.c
@@ -1207,8 +1207,6 @@ static int build_body(struct jit_ctx *ctx)
return 0;
}
-int bpf_jit_enable __read_mostly;
-
void bpf_jit_compile(struct bpf_prog *fp)
{
struct jit_ctx ctx;
diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index 8004bfcfb033..42faa95ce664 100644
--- a/arch/mips/net/ebpf_jit.c
+++ b/arch/mips/net/ebpf_jit.c
@@ -177,8 +177,6 @@ static u32 b_imm(unsigned int tgt, struct jit_ctx *ctx)
(ctx->idx * 4) - 4;
}
-int bpf_jit_enable __read_mostly;
-
enum which_ebpf_reg {
src_reg,
src_reg_no_fp,
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index f760494ecd66..a9636d8cba15 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -18,8 +18,6 @@
#include "bpf_jit32.h"
-int bpf_jit_enable __read_mostly;
-
static inline void bpf_flush_icache(void *start, void *end)
{
smp_wmb();
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 70e8216a39f0..28434040cfb6 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -21,8 +21,6 @@
#include "bpf_jit64.h"
-int bpf_jit_enable __read_mostly;
-
static void bpf_jit_fill_ill_insns(void *area, unsigned int size)
{
memset32(area, BREAKPOINT_INSTRUCTION, size/4);
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 6b1474fa99ab..bc9431aace05 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -30,8 +30,6 @@
#include <asm/set_memory.h>
#include "bpf_jit.h"
-int bpf_jit_enable __read_mostly;
-
struct bpf_jit {
u32 seen; /* Flags to remember seen eBPF instructions */
u32 seen_reg[16]; /* Array to remember which registers are used */
diff --git a/arch/sparc/net/bpf_jit_comp_32.c b/arch/sparc/net/bpf_jit_comp_32.c
index 09e318eb34ee..3bd8ca95e521 100644
--- a/arch/sparc/net/bpf_jit_comp_32.c
+++ b/arch/sparc/net/bpf_jit_comp_32.c
@@ -11,8 +11,6 @@
#include "bpf_jit_32.h"
-int bpf_jit_enable __read_mostly;
-
static inline bool is_simm13(unsigned int value)
{
return value + 0x1000 < 0x2000;
diff --git a/arch/sparc/net/bpf_jit_comp_64.c b/arch/sparc/net/bpf_jit_comp_64.c
index ff5f9cb3039a..adfb4581bd80 100644
--- a/arch/sparc/net/bpf_jit_comp_64.c
+++ b/arch/sparc/net/bpf_jit_comp_64.c
@@ -12,8 +12,6 @@
#include "bpf_jit_64.h"
-int bpf_jit_enable __read_mostly;
-
static inline bool is_simm13(unsigned int value)
{
return value + 0x1000 < 0x2000;
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index a9deb2b0397d..cdb386fa7101 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -16,8 +16,6 @@
#include <asm/nospec-branch.h>
#include <linux/bpf.h>
-int bpf_jit_enable __read_mostly;
-
/*
* assembly code in arch/x86/net/bpf_jit.S
*/
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index e46106c6ac39..661fb837b168 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -290,6 +290,11 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
}
#ifdef CONFIG_BPF_JIT
+/* All BPF JIT sysctl knobs here. */
+int bpf_jit_enable __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_ALWAYS_ON);
+int bpf_jit_harden __read_mostly;
+int bpf_jit_kallsyms __read_mostly;
+
static __always_inline void
bpf_get_prog_addr_region(const struct bpf_prog *prog,
unsigned long *symbol_start,
@@ -358,8 +363,6 @@ static DEFINE_SPINLOCK(bpf_lock);
static LIST_HEAD(bpf_kallsyms);
static struct latch_tree_root bpf_tree __cacheline_aligned;
-int bpf_jit_kallsyms __read_mostly;
-
static void bpf_prog_ksym_node_add(struct bpf_prog_aux *aux)
{
WARN_ON_ONCE(!list_empty(&aux->ksym_lnode));
@@ -540,8 +543,6 @@ void __weak bpf_jit_free(struct bpf_prog *fp)
bpf_prog_unlock_free(fp);
}
-int bpf_jit_harden __read_mostly;
-
static int bpf_jit_blind_insn(const struct bpf_insn *from,
const struct bpf_insn *aux,
struct bpf_insn *to_buff)
@@ -1327,9 +1328,13 @@ EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
};
#else
-static unsigned int __bpf_prog_ret0(const void *ctx,
- const struct bpf_insn *insn)
+static unsigned int __bpf_prog_ret0_warn(const void *ctx,
+ const struct bpf_insn *insn)
{
+ /* If this handler ever gets executed, then BPF_JIT_ALWAYS_ON
+ * is not working properly, so warn about it!
+ */
+ WARN_ON_ONCE(1);
return 0;
}
#endif
@@ -1386,7 +1391,7 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
fp->bpf_func = interpreters[(round_up(stack_depth, 32) / 32) - 1];
#else
- fp->bpf_func = __bpf_prog_ret0;
+ fp->bpf_func = __bpf_prog_ret0_warn;
#endif
/* eBPF JITs can rewrite the program in case constant
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index a47ad6cd41c0..6d39b4c01fc6 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -25,6 +25,7 @@
static int zero = 0;
static int one = 1;
+static int two __maybe_unused = 2;
static int min_sndbuf = SOCK_MIN_SNDBUF;
static int min_rcvbuf = SOCK_MIN_RCVBUF;
static int max_skb_frags = MAX_SKB_FRAGS;
@@ -325,13 +326,14 @@ 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,
+# ifdef CONFIG_BPF_JIT_ALWAYS_ON
.extra1 = &one,
.extra2 = &one,
-#endif
+# else
+ .extra1 = &zero,
+ .extra2 = &two,
+# endif
},
# ifdef CONFIG_HAVE_EBPF_JIT
{
@@ -339,14 +341,18 @@ static struct ctl_table net_core_table[] = {
.data = &bpf_jit_harden,
.maxlen = sizeof(int),
.mode = 0600,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &two,
},
{
.procname = "bpf_jit_kallsyms",
.data = &bpf_jit_kallsyms,
.maxlen = sizeof(int),
.mode = 0600,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &one,
},
# endif
#endif
diff --git a/net/socket.c b/net/socket.c
index 6d8f0c248c7e..aab65277314d 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2656,15 +2656,6 @@ static int __init sock_init(void)
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)
{
--
Ben Hutchings, Software Developer Codethink Ltd
https://www.codethink.co.uk/ Dale House, 35 Dale Street
Manchester, M1 2HF, United Kingdom
