Merge branch 'bpf-prog-digest'

Daniel Borkmann says:

====================
Minor BPF cleanups and digest

First two patches are minor cleanups, and the third one adds
a prog digest. For details, please see individual patches.
After this one, I have a set with tracepoint support that makes
use of this facility as well.
====================

Signed-off-by: David S. Miller <[email protected]>

include/linux/bpf.h

@@ -216,6 +216,7 @@ u64 bpf_tail_call(u64 ctx, u64 r2, u64 index, u64 r4, u64 r5);
 u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 
 bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
+void bpf_prog_calc_digest(struct bpf_prog *fp);
 
 const struct bpf_func_proto *bpf_get_trace_printk_proto(void);
 

include/linux/filter.h

@@ -14,6 +14,7 @@
 #include <linux/workqueue.h>
 #include <linux/sched.h>
 #include <linux/capability.h>
+#include <linux/cryptohash.h>
 
 #include <net/sch_generic.h>
 
@@ -56,6 +57,9 @@ struct bpf_prog_aux;
 /* BPF program can access up to 512 bytes of stack space. */
 #define MAX_BPF_STACK	512
 
+/* Maximum BPF program size in bytes. */
+#define MAX_BPF_SIZE	(BPF_MAXINSNS * sizeof(struct bpf_insn))
+
 /* Helper macros for filter block array initializers. */
 
 /* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */
@@ -404,8 +408,9 @@ struct bpf_prog {
 				cb_access:1,	/* Is control block accessed? */
 				dst_needed:1;	/* Do we need dst entry? */
 	kmemcheck_bitfield_end(meta);
-	u32			len;		/* Number of filter blocks */
 	enum bpf_prog_type	type;		/* Type of BPF program */
+	u32			len;		/* Number of filter blocks */
+	u32			digest[SHA_DIGEST_WORDS]; /* Program digest */
 	struct bpf_prog_aux	*aux;		/* Auxiliary fields */
 	struct sock_fprog_kern	*orig_prog;	/* Original BPF program */
 	unsigned int		(*bpf_func)(const void *ctx,

include/uapi/linux/pkt_cls.h

@@ -397,6 +397,7 @@ enum {
 	TCA_BPF_NAME,
 	TCA_BPF_FLAGS,
 	TCA_BPF_FLAGS_GEN,
+	TCA_BPF_DIGEST,
 	__TCA_BPF_MAX,
 };
 

include/uapi/linux/tc_act/tc_bpf.h

@@ -27,6 +27,7 @@ enum {
 	TCA_ACT_BPF_FD,
 	TCA_ACT_BPF_NAME,
 	TCA_ACT_BPF_PAD,
+	TCA_ACT_BPF_DIGEST,
 	__TCA_ACT_BPF_MAX,
 };
 #define TCA_ACT_BPF_MAX (__TCA_ACT_BPF_MAX - 1)

kernel/bpf/core.c

@@ -136,6 +136,71 @@ void __bpf_prog_free(struct bpf_prog *fp)
 	vfree(fp);
 }
 
+#define SHA_BPF_RAW_SIZE						\
+	round_up(MAX_BPF_SIZE + sizeof(__be64) + 1, SHA_MESSAGE_BYTES)
+
+/* Called under verifier mutex. */
+void bpf_prog_calc_digest(struct bpf_prog *fp)
+{
+	const u32 bits_offset = SHA_MESSAGE_BYTES - sizeof(__be64);
+	static u32 ws[SHA_WORKSPACE_WORDS];
+	static u8 raw[SHA_BPF_RAW_SIZE];
+	struct bpf_insn *dst = (void *)raw;
+	u32 i, bsize, psize, blocks;
+	bool was_ld_map;
+	u8 *todo = raw;
+	__be32 *result;
+	__be64 *bits;
+
+	sha_init(fp->digest);
+	memset(ws, 0, sizeof(ws));
+
+	/* We need to take out the map fd for the digest calculation
+	 * since they are unstable from user space side.
+	 */
+	for (i = 0, was_ld_map = false; i < fp->len; i++) {
+		dst[i] = fp->insnsi[i];
+		if (!was_ld_map &&
+		    dst[i].code == (BPF_LD | BPF_IMM | BPF_DW) &&
+		    dst[i].src_reg == BPF_PSEUDO_MAP_FD) {
+			was_ld_map = true;
+			dst[i].imm = 0;
+		} else if (was_ld_map &&
+			   dst[i].code == 0 &&
+			   dst[i].dst_reg == 0 &&
+			   dst[i].src_reg == 0 &&
+			   dst[i].off == 0) {
+			was_ld_map = false;
+			dst[i].imm = 0;
+		} else {
+			was_ld_map = false;
+		}
+	}
+
+	psize = fp->len * sizeof(struct bpf_insn);
+	memset(&raw[psize], 0, sizeof(raw) - psize);
+	raw[psize++] = 0x80;
+
+	bsize  = round_up(psize, SHA_MESSAGE_BYTES);
+	blocks = bsize / SHA_MESSAGE_BYTES;
+	if (bsize - psize >= sizeof(__be64)) {
+		bits = (__be64 *)(todo + bsize - sizeof(__be64));
+	} else {
+		bits = (__be64 *)(todo + bsize + bits_offset);
+		blocks++;
+	}
+	*bits = cpu_to_be64((psize - 1) << 3);
+
+	while (blocks--) {
+		sha_transform(fp->digest, todo, ws);
+		todo += SHA_MESSAGE_BYTES;
+	}
+
+	result = (__force __be32 *)fp->digest;
+	for (i = 0; i < SHA_DIGEST_WORDS; i++)
+		result[i] = cpu_to_be32(fp->digest[i]);
+}
+
 static bool bpf_is_jmp_and_has_target(const struct bpf_insn *insn)
 {
 	return BPF_CLASS(insn->code) == BPF_JMP  &&

kernel/bpf/syscall.c

@@ -662,8 +662,30 @@ static int bpf_prog_release(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+#ifdef CONFIG_PROC_FS
+static void bpf_prog_show_fdinfo(struct seq_file *m, struct file *filp)
+{
+	const struct bpf_prog *prog = filp->private_data;
+	char prog_digest[sizeof(prog->digest) * 2 + 1] = { };
+
+	bin2hex(prog_digest, prog->digest, sizeof(prog->digest));
+	seq_printf(m,
+		   "prog_type:\t%u\n"
+		   "prog_jited:\t%u\n"
+		   "prog_digest:\t%s\n"
+		   "memlock:\t%llu\n",
+		   prog->type,
+		   prog->jited,
+		   prog_digest,
+		   prog->pages * 1ULL << PAGE_SHIFT);
+}
+#endif
+
 static const struct file_operations bpf_prog_fops = {
-        .release = bpf_prog_release,
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo	= bpf_prog_show_fdinfo,
+#endif
+	.release	= bpf_prog_release,
 };
 
 int bpf_prog_new_fd(struct bpf_prog *prog)

kernel/bpf/verifier.c

@@ -3176,6 +3176,8 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
 		log_level = 0;
 	}
 
+	bpf_prog_calc_digest(env->prog);
+
 	ret = replace_map_fd_with_map_ptr(env);
 	if (ret < 0)
 		goto skip_full_check;

net/core/filter.c

@@ -2748,7 +2748,7 @@ lwt_xmit_func_proto(enum bpf_func_id func_id)
 	}
 }
 
-static bool __is_valid_access(int off, int size, enum bpf_access_type type)
+static bool __is_valid_access(int off, int size)
 {
 	if (off < 0 || off >= sizeof(struct __sk_buff))
 		return false;
@@ -2782,7 +2782,7 @@ static bool sk_filter_is_valid_access(int off, int size,
 		}
 	}
 
-	return __is_valid_access(off, size, type);
+	return __is_valid_access(off, size);
 }
 
 static bool lwt_is_valid_access(int off, int size,
@@ -2815,7 +2815,7 @@ static bool lwt_is_valid_access(int off, int size,
 		break;
 	}
 
-	return __is_valid_access(off, size, type);
+	return __is_valid_access(off, size);
 }
 
 static bool sock_filter_is_valid_access(int off, int size,
@@ -2833,11 +2833,9 @@ static bool sock_filter_is_valid_access(int off, int size,
 
 	if (off < 0 || off + size > sizeof(struct bpf_sock))
 		return false;
-
 	/* The verifier guarantees that size > 0. */
 	if (off % size != 0)
 		return false;
-
 	if (size != sizeof(__u32))
 		return false;
 
@@ -2910,11 +2908,10 @@ static bool tc_cls_act_is_valid_access(int off, int size,
 		break;
 	}
 
-	return __is_valid_access(off, size, type);
+	return __is_valid_access(off, size);
 }
 
-static bool __is_valid_xdp_access(int off, int size,
-				  enum bpf_access_type type)
+static bool __is_valid_xdp_access(int off, int size)
 {
 	if (off < 0 || off >= sizeof(struct xdp_md))
 		return false;
@@ -2942,7 +2939,7 @@ static bool xdp_is_valid_access(int off, int size,
 		break;
 	}
 
-	return __is_valid_xdp_access(off, size, type);
+	return __is_valid_xdp_access(off, size);
 }
 
 void bpf_warn_invalid_xdp_action(u32 act)

net/sched/act_bpf.c

@@ -117,10 +117,19 @@ static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
 				  struct sk_buff *skb)
 {
+	struct nlattr *nla;
+
 	if (prog->bpf_name &&
 	    nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 		return -EMSGSIZE;
 
+	nla = nla_reserve(skb, TCA_ACT_BPF_DIGEST,
+			  sizeof(prog->filter->digest));
+	if (nla == NULL)
+		return -EMSGSIZE;
+
+	memcpy(nla_data(nla), prog->filter->digest, nla_len(nla));
+
 	return 0;
 }
 

net/sched/cls_bpf.c

@@ -241,7 +241,7 @@ static int cls_bpf_init(struct tcf_proto *tp)
 	return 0;
 }
 
-static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog)
+static void __cls_bpf_delete_prog(struct cls_bpf_prog *prog)
 {
 	tcf_exts_destroy(&prog->exts);
 
@@ -255,22 +255,22 @@ static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog)
 	kfree(prog);
 }
 
-static void __cls_bpf_delete_prog(struct rcu_head *rcu)
+static void cls_bpf_delete_prog_rcu(struct rcu_head *rcu)
 {
-	struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu);
-
-	cls_bpf_delete_prog(prog->tp, prog);
+	__cls_bpf_delete_prog(container_of(rcu, struct cls_bpf_prog, rcu));
 }
 
-static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
+static void __cls_bpf_delete(struct tcf_proto *tp, struct cls_bpf_prog *prog)
 {
-	struct cls_bpf_prog *prog = (struct cls_bpf_prog *) arg;
-
 	cls_bpf_stop_offload(tp, prog);
 	list_del_rcu(&prog->link);
 	tcf_unbind_filter(tp, &prog->res);
-	call_rcu(&prog->rcu, __cls_bpf_delete_prog);
+	call_rcu(&prog->rcu, cls_bpf_delete_prog_rcu);
+}
 
+static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
+{
+	__cls_bpf_delete(tp, (struct cls_bpf_prog *) arg);
 	return 0;
 }
 
@@ -282,12 +282,8 @@ static bool cls_bpf_destroy(struct tcf_proto *tp, bool force)
 	if (!force && !list_empty(&head->plist))
 		return false;
 
-	list_for_each_entry_safe(prog, tmp, &head->plist, link) {
-		cls_bpf_stop_offload(tp, prog);
-		list_del_rcu(&prog->link);
-		tcf_unbind_filter(tp, &prog->res);
-		call_rcu(&prog->rcu, __cls_bpf_delete_prog);
-	}
+	list_for_each_entry_safe(prog, tmp, &head->plist, link)
+		__cls_bpf_delete(tp, prog);
 
 	kfree_rcu(head, rcu);
 	return true;
@@ -511,14 +507,14 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
 
 	ret = cls_bpf_offload(tp, prog, oldprog);
 	if (ret) {
-		cls_bpf_delete_prog(tp, prog);
+		__cls_bpf_delete_prog(prog);
 		return ret;
 	}
 
 	if (oldprog) {
 		list_replace_rcu(&oldprog->link, &prog->link);
 		tcf_unbind_filter(tp, &oldprog->res);
-		call_rcu(&oldprog->rcu, __cls_bpf_delete_prog);
+		call_rcu(&oldprog->rcu, cls_bpf_delete_prog_rcu);
 	} else {
 		list_add_rcu(&prog->link, &head->plist);
 	}
@@ -553,10 +549,18 @@ static int cls_bpf_dump_bpf_info(const struct cls_bpf_prog *prog,
 static int cls_bpf_dump_ebpf_info(const struct cls_bpf_prog *prog,
 				  struct sk_buff *skb)
 {
+	struct nlattr *nla;
+
 	if (prog->bpf_name &&
 	    nla_put_string(skb, TCA_BPF_NAME, prog->bpf_name))
 		return -EMSGSIZE;
 
+	nla = nla_reserve(skb, TCA_BPF_DIGEST, sizeof(prog->filter->digest));
+	if (nla == NULL)
+		return -EMSGSIZE;
+
+	memcpy(nla_data(nla), prog->filter->digest, nla_len(nla));
+
 	return 0;
 }