From 19729e1302017ef33e139903b28f9a778b2a8748 Mon Sep 17 00:00:00 2001

From: Andrea Claudi <aclaudi@redhat.com>

Date: Thu, 13 Jun 2019 14:37:56 +0200

Subject: [PATCH] bpf: remove strict dependency on af_alg

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1716361

Upstream Status: iproute2.git commit 6e5094dbb7c06

commit 6e5094dbb7c0682a9ca6eb2a64ec51f0a8a33a22

Author: Daniel Borkmann <daniel@iogearbox.net>

Date:   Wed Jul 18 01:31:20 2018 +0200

    bpf: remove strict dependency on af_alg

    Do not bail out when AF_ALG is not supported by the kernel and

    only do so when a map is requested in object ns where we're

    calculating the hash. Otherwise, the loader can operate just

    fine, therefore lets not fail early when it's not needed.

    Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

    Signed-off-by: David Ahern <dsahern@gmail.com>

---

 lib/bpf.c | 74 +++++++++++++++++++++----------------------------------

 1 file changed, 28 insertions(+), 46 deletions(-)

diff --git a/lib/bpf.c b/lib/bpf.c

index 9dc37c787d907..ead8b5a7219f0 100644

--- a/lib/bpf.c

+++ b/lib/bpf.c

@@ -1130,6 +1130,7 @@ struct bpf_elf_ctx {

 	GElf_Ehdr		elf_hdr;

 	Elf_Data		*sym_tab;

 	Elf_Data		*str_tab;

+	char			obj_uid[64];

 	int			obj_fd;

 	int			map_fds[ELF_MAX_MAPS];

 	struct bpf_elf_map	maps[ELF_MAX_MAPS];

@@ -1143,6 +1144,7 @@ struct bpf_elf_ctx {

 	enum bpf_prog_type	type;

 	__u32			ifindex;

 	bool			verbose;

+	bool			noafalg;

 	struct bpf_elf_st	stat;

 	struct bpf_hash_entry	*ht[256];

 	char			*log;

@@ -1258,22 +1260,15 @@ static int bpf_obj_hash(const char *object, uint8_t *out, size_t len)

 		return -EINVAL;

 	cfd = socket(AF_ALG, SOCK_SEQPACKET, 0);

-	if (cfd < 0) {

-		fprintf(stderr, "Cannot get AF_ALG socket: %s\n",

-			strerror(errno));

+	if (cfd < 0)

 		return cfd;

-	}

 	ret = bind(cfd, (struct sockaddr *)&alg, sizeof(alg));

-	if (ret < 0) {

-		fprintf(stderr, "Error binding socket: %s\n", strerror(errno));

+	if (ret < 0)

 		goto out_cfd;

-	}

 	ofd = accept(cfd, NULL, 0);

 	if (ofd < 0) {

-		fprintf(stderr, "Error accepting socket: %s\n",

-			strerror(errno));

 		ret = ofd;

 		goto out_cfd;

 	}

@@ -1318,29 +1313,7 @@ out_cfd:

 	return ret;

 }

-static const char *bpf_get_obj_uid(const char *pathname)

-{

-	static bool bpf_uid_cached;

-	static char bpf_uid[64];

-	uint8_t tmp[20];

-	int ret;

-

-	if (bpf_uid_cached)

-		goto done;

-

-	ret = bpf_obj_hash(pathname, tmp, sizeof(tmp));

-	if (ret) {

-		fprintf(stderr, "Object hashing failed!\n");

-		return NULL;

-	}

-

-	hexstring_n2a(tmp, sizeof(tmp), bpf_uid, sizeof(bpf_uid));

-	bpf_uid_cached = true;

-done:

-	return bpf_uid;

-}

-

-static int bpf_init_env(const char *pathname)

+static void bpf_init_env(void)

 {

 	struct rlimit limit = {

 		.rlim_cur = RLIM_INFINITY,

@@ -1350,15 +1323,8 @@ static int bpf_init_env(const char *pathname)

 	/* Don't bother in case we fail! */

 	setrlimit(RLIMIT_MEMLOCK, &limit);

-	if (!bpf_get_work_dir(BPF_PROG_TYPE_UNSPEC)) {

+	if (!bpf_get_work_dir(BPF_PROG_TYPE_UNSPEC))

 		fprintf(stderr, "Continuing without mounted eBPF fs. Too old kernel?\n");

-		return 0;

-	}

-

-	if (!bpf_get_obj_uid(pathname))

-		return -1;

-

-	return 0;

 }

 static const char *bpf_custom_pinning(const struct bpf_elf_ctx *ctx,

@@ -1394,7 +1360,7 @@ static void bpf_make_pathname(char *pathname, size_t len, const char *name,

 	case PIN_OBJECT_NS:

 		snprintf(pathname, len, "%s/%s/%s",

 			 bpf_get_work_dir(ctx->type),

-			 bpf_get_obj_uid(NULL), name);

+			 ctx->obj_uid, name);

 		break;

 	case PIN_GLOBAL_NS:

 		snprintf(pathname, len, "%s/%s/%s",

@@ -1427,7 +1393,7 @@ static int bpf_make_obj_path(const struct bpf_elf_ctx *ctx)

 	int ret;

 	snprintf(tmp, sizeof(tmp), "%s/%s", bpf_get_work_dir(ctx->type),

-		 bpf_get_obj_uid(NULL));

+		 ctx->obj_uid);

 	ret = mkdir(tmp, S_IRWXU);

 	if (ret && errno != EEXIST) {

@@ -1696,6 +1662,12 @@ static int bpf_maps_attach_all(struct bpf_elf_ctx *ctx)

 	const char *map_name;

 	for (i = 0; i < ctx->map_num; i++) {

+		if (ctx->maps[i].pinning == PIN_OBJECT_NS &&

+		    ctx->noafalg) {

+			fprintf(stderr, "Missing kernel AF_ALG support for PIN_OBJECT_NS!\n");

+			return -ENOTSUP;

+		}

+

 		map_name = bpf_map_fetch_name(ctx, i);

 		if (!map_name)

 			return -EIO;

@@ -2451,14 +2423,24 @@ static int bpf_elf_ctx_init(struct bpf_elf_ctx *ctx, const char *pathname,

 			    enum bpf_prog_type type, __u32 ifindex,

 			    bool verbose)

 {

-	int ret = -EINVAL;

+	uint8_t tmp[20];

+	int ret;

-	if (elf_version(EV_CURRENT) == EV_NONE ||

-	    bpf_init_env(pathname))

-		return ret;

+	if (elf_version(EV_CURRENT) == EV_NONE)

+		return -EINVAL;

+

+	bpf_init_env();

 	memset(ctx, 0, sizeof(*ctx));

 	bpf_get_cfg(ctx);

+

+	ret = bpf_obj_hash(pathname, tmp, sizeof(tmp));

+	if (ret)

+		ctx->noafalg = true;

+	else

+		hexstring_n2a(tmp, sizeof(tmp), ctx->obj_uid,

+			      sizeof(ctx->obj_uid));

+

 	ctx->verbose = verbose;

 	ctx->type    = type;

 	ctx->ifindex = ifindex;

-- 

2.20.1