diff --git a/include/linux/filter.h b/include/linux/filter.h
index 297c56fa9cee05254a9fd75696814ee02c70f356..108f9812e1968d1552f42044daee7c2ea013d897 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -469,7 +469,8 @@ struct sock_fprog_kern {
};
struct bpf_binary_header {
- unsigned int pages;
+ u16 pages;
+ u16 locked:1;
u8 image[];
};
@@ -671,15 +672,18 @@ bpf_ctx_narrow_access_ok(u32 off, u32 size, u32 size_default)
#define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0]))
-#ifdef CONFIG_ARCH_HAS_SET_MEMORY
static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
{
+#ifdef CONFIG_ARCH_HAS_SET_MEMORY
fp->locked = 1;
- WARN_ON_ONCE(set_memory_ro((unsigned long)fp, fp->pages));
+ if (set_memory_ro((unsigned long)fp, fp->pages))
+ fp->locked = 0;
+#endif
}
static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
{
+#ifdef CONFIG_ARCH_HAS_SET_MEMORY
if (fp->locked) {
WARN_ON_ONCE(set_memory_rw((unsigned long)fp, fp->pages));
/* In case set_memory_rw() fails, we want to be the first
@@ -687,34 +691,30 @@ static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
*/
fp->locked = 0;
}
+#endif
}
static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)
{
- WARN_ON_ONCE(set_memory_ro((unsigned long)hdr, hdr->pages));
-}
-
-static inline void bpf_jit_binary_unlock_ro(struct bpf_binary_header *hdr)
-{
- WARN_ON_ONCE(set_memory_rw((unsigned long)hdr, hdr->pages));
-}
-#else
-static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
-{
-}
-
-static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
-{
-}
-
-static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)
-{
+#ifdef CONFIG_ARCH_HAS_SET_MEMORY
+ hdr->locked = 1;
+ if (set_memory_ro((unsigned long)hdr, hdr->pages))
+ hdr->locked = 0;
+#endif
}
static inline void bpf_jit_binary_unlock_ro(struct bpf_binary_header *hdr)
{
+#ifdef CONFIG_ARCH_HAS_SET_MEMORY
+ if (hdr->locked) {
+ WARN_ON_ONCE(set_memory_rw((unsigned long)hdr, hdr->pages));
+ /* In case set_memory_rw() fails, we want to be the first
+ * to crash here instead of some random place later on.
+ */
+ hdr->locked = 0;
+ }
+#endif
}
-#endif /* CONFIG_ARCH_HAS_SET_MEMORY */
static inline struct bpf_binary_header *
bpf_jit_binary_hdr(const struct bpf_prog *fp)
@@ -725,6 +725,22 @@ bpf_jit_binary_hdr(const struct bpf_prog *fp)
return (void *)addr;
}
+#ifdef CONFIG_ARCH_HAS_SET_MEMORY
+static inline int bpf_prog_check_pages_ro_single(const struct bpf_prog *fp)
+{
+ if (!fp->locked)
+ return -ENOLCK;
+ if (fp->jited) {
+ const struct bpf_binary_header *hdr = bpf_jit_binary_hdr(fp);
+
+ if (!hdr->locked)
+ return -ENOLCK;
+ }
+
+ return 0;
+}
+#endif
+
int sk_filter_trim_cap(struct sock *sk, struct sk_buff *skb, unsigned int cap);
static inline int sk_filter(struct sock *sk, struct sk_buff *skb)
{
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 1061968adcc1b28ae4f96034a76ec5a7eefc1d22..a9e6c04d0f4ad5a105aa8aeff99058479131e9e1 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -598,6 +598,8 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
bpf_fill_ill_insns(hdr, size);
hdr->pages = size / PAGE_SIZE;
+ hdr->locked = 0;
+
hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)),
PAGE_SIZE - sizeof(*hdr));
start = (get_random_int() % hole) & ~(alignment - 1);
@@ -1448,6 +1450,33 @@ static int bpf_check_tail_call(const struct bpf_prog *fp)
return 0;
}
+static int bpf_prog_check_pages_ro_locked(const struct bpf_prog *fp)
+{
+#ifdef CONFIG_ARCH_HAS_SET_MEMORY
+ int i, err;
+
+ for (i = 0; i < fp->aux->func_cnt; i++) {
+ err = bpf_prog_check_pages_ro_single(fp->aux->func[i]);
+ if (err)
+ return err;
+ }
+
+ return bpf_prog_check_pages_ro_single(fp);
+#endif
+ return 0;
+}
+
+static void bpf_prog_select_func(struct bpf_prog *fp)
+{
+#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_warn;
+#endif
+}
+
/**
* bpf_prog_select_runtime - select exec runtime for BPF program
* @fp: bpf_prog populated with internal BPF program
@@ -1458,13 +1487,13 @@ 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);
+ /* In case of BPF to BPF calls, verifier did all the prep
+ * work with regards to JITing, etc.
+ */
+ if (fp->bpf_func)
+ goto finalize;
- fp->bpf_func = interpreters[(round_up(stack_depth, 32) / 32) - 1];
-#else
- fp->bpf_func = __bpf_prog_ret0_warn;
-#endif
+ bpf_prog_select_func(fp);
/* eBPF JITs can rewrite the program in case constant
* blinding is active. However, in case of error during
@@ -1485,6 +1514,8 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
if (*err)
return fp;
}
+
+finalize:
bpf_prog_lock_ro(fp);
/* The tail call compatibility check can only be done at
@@ -1493,7 +1524,17 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
* all eBPF JITs might immediately support all features.
*/
*err = bpf_check_tail_call(fp);
-
+ if (*err)
+ return fp;
+
+ /* Checkpoint: at this point onwards any cBPF -> eBPF or
+ * native eBPF program is read-only. If we failed to change
+ * the page attributes (e.g. allocation failure from
+ * splitting large pages), then reject the whole program
+ * in order to guarantee not ending up with any W+X pages
+ * from BPF side in kernel.
+ */
+ *err = bpf_prog_check_pages_ro_locked(fp);
return fp;
}
EXPORT_SYMBOL_GPL(bpf_prog_select_runtime);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 0f62692fe63506aa818de58265e709429c765ff3..35dc466641f2609cdd13a6f179e81c877144e5c7 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1353,9 +1353,7 @@ static int bpf_prog_load(union bpf_attr *attr)
if (err < 0)
goto free_used_maps;
- /* eBPF program is ready to be JITed */
- if (!prog->bpf_func)
- prog = bpf_prog_select_runtime(prog, &err);
+ prog = bpf_prog_select_runtime(prog, &err);
if (err < 0)
goto free_used_maps;