diff mbox series

[v3,3/3] bpf: prevent increasing bpf_jit_limit above max

Message ID 20211014142554.53120-4-lmb@cloudflare.com (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series Fix up bpf_jit_limit some more | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch
bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf success VM_Test
bpf/vmtest-bpf-PR success PR summary
bpf/vmtest-bpf-next success VM_Test

Commit Message

Lorenz Bauer Oct. 14, 2021, 2:25 p.m. UTC 
Restrict bpf_jit_limit to the maximum supported by the arch's JIT.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
---
 include/linux/filter.h     | 1 +
 kernel/bpf/core.c          | 4 +++-
 net/core/sysctl_net_core.c | 2 +-
 3 files changed, 5 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 47f80adbe744..8231a6a257f6 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1050,6 +1050,7 @@  extern int bpf_jit_enable;
 extern int bpf_jit_harden;
 extern int bpf_jit_kallsyms;
 extern long bpf_jit_limit;
+extern long bpf_jit_limit_max;
 
 typedef void (*bpf_jit_fill_hole_t)(void *area, unsigned int size);
 
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index b6c72af64d5d..ab84b3816339 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -525,6 +525,7 @@  int bpf_jit_enable   __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_DEFAULT_ON);
 int bpf_jit_kallsyms __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_DEFAULT_ON);
 int bpf_jit_harden   __read_mostly;
 long bpf_jit_limit   __read_mostly;
+long bpf_jit_limit_max __read_mostly;
 
 static void
 bpf_prog_ksym_set_addr(struct bpf_prog *prog)
@@ -818,7 +819,8 @@  u64 __weak bpf_jit_alloc_exec_limit(void)
 static int __init bpf_jit_charge_init(void)
 {
 	/* Only used as heuristic here to derive limit. */
-	bpf_jit_limit = min_t(u64, round_up(bpf_jit_alloc_exec_limit() >> 2,
+	bpf_jit_limit_max = bpf_jit_alloc_exec_limit();
+	bpf_jit_limit = min_t(u64, round_up(bpf_jit_limit_max >> 2,
 					    PAGE_SIZE), LONG_MAX);
 	return 0;
 }
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index c8496c1142c9..5f88526ad61c 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -419,7 +419,7 @@  static struct ctl_table net_core_table[] = {
 		.mode		= 0600,
 		.proc_handler	= proc_dolongvec_minmax_bpf_restricted,
 		.extra1		= &long_one,
-		.extra2		= &long_max,
+		.extra2		= &bpf_jit_limit_max,
 	},
 #endif
 	{