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Message-Id: <c25efdff9a67ed4bc23862d0ef4ff8073de69c4e.1568638725.git.aclaudi@redhat.com>
Date: Mon, 16 Sep 2019 15:00:55 +0200
From: Andrea Claudi <aclaudi@...hat.com>
To: netdev@...r.kernel.org
Cc: stephen@...workplumber.org, dsahern@...nel.org
Subject: [PATCH iproute2-next v2] bpf: replace snprintf with asprintf when dealing with long buffers
This reduces stack usage, as asprintf allocates memory on the heap.
This indirectly fixes a snprintf truncation warning (from gcc v9.2.1):
bpf.c: In function ‘bpf_get_work_dir’:
bpf.c:784:49: warning: ‘snprintf’ output may be truncated before the last format character [-Wformat-truncation=]
784 | snprintf(bpf_wrk_dir, sizeof(bpf_wrk_dir), "%s/", mnt);
| ^
bpf.c:784:2: note: ‘snprintf’ output between 2 and 4097 bytes into a destination of size 4096
784 | snprintf(bpf_wrk_dir, sizeof(bpf_wrk_dir), "%s/", mnt);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fixes: e42256699cac ("bpf: make tc's bpf loader generic and move into lib")
Signed-off-by: Andrea Claudi <aclaudi@...hat.com>
---
lib/bpf.c | 155 ++++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 116 insertions(+), 39 deletions(-)
diff --git a/lib/bpf.c b/lib/bpf.c
index 7d2a322ffbaec..0fe2e9eb2cbf8 100644
--- a/lib/bpf.c
+++ b/lib/bpf.c
@@ -406,13 +406,21 @@ static int bpf_derive_elf_map_from_fdinfo(int fd, struct bpf_elf_map *map,
struct bpf_map_ext *ext)
{
unsigned int val, owner_type = 0, owner_jited = 0;
- char file[PATH_MAX], buff[4096];
+ char *file = NULL;
+ char buff[4096];
FILE *fp;
+ int ret;
- snprintf(file, sizeof(file), "/proc/%d/fdinfo/%d", getpid(), fd);
+ ret = asprintf(&file, "/proc/%d/fdinfo/%d", getpid(), fd);
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ free(file);
+ return ret;
+ }
memset(map, 0, sizeof(*map));
fp = fopen(file, "r");
+ free(file);
if (!fp) {
fprintf(stderr, "No procfs support?!\n");
return -EIO;
@@ -600,8 +608,9 @@ int bpf_trace_pipe(void)
0,
};
int fd_in, fd_out = STDERR_FILENO;
- char tpipe[PATH_MAX];
+ char *tpipe = NULL;
const char *mnt;
+ int ret;
mnt = bpf_find_mntpt("tracefs", TRACEFS_MAGIC, tracefs_mnt,
sizeof(tracefs_mnt), tracefs_known_mnts);
@@ -610,9 +619,15 @@ int bpf_trace_pipe(void)
return -1;
}
- snprintf(tpipe, sizeof(tpipe), "%s/trace_pipe", mnt);
+ ret = asprintf(&tpipe, "%s/trace_pipe", mnt);
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ free(tpipe);
+ return ret;
+ }
fd_in = open(tpipe, O_RDONLY);
+ free(tpipe);
if (fd_in < 0)
return -1;
@@ -633,37 +648,50 @@ int bpf_trace_pipe(void)
static int bpf_gen_global(const char *bpf_sub_dir)
{
- char bpf_glo_dir[PATH_MAX];
+ char *bpf_glo_dir = NULL;
int ret;
- snprintf(bpf_glo_dir, sizeof(bpf_glo_dir), "%s/%s/",
- bpf_sub_dir, BPF_DIR_GLOBALS);
+ ret = asprintf(&bpf_glo_dir, "%s/%s/", bpf_sub_dir, BPF_DIR_GLOBALS);
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ goto out;
+ }
ret = mkdir(bpf_glo_dir, S_IRWXU);
if (ret && errno != EEXIST) {
fprintf(stderr, "mkdir %s failed: %s\n", bpf_glo_dir,
strerror(errno));
- return ret;
+ goto out;
}
- return 0;
+ ret = 0;
+out:
+ free(bpf_glo_dir);
+ return ret;
}
static int bpf_gen_master(const char *base, const char *name)
{
- char bpf_sub_dir[PATH_MAX + NAME_MAX + 1];
+ char *bpf_sub_dir = NULL;
int ret;
- snprintf(bpf_sub_dir, sizeof(bpf_sub_dir), "%s%s/", base, name);
+ ret = asprintf(&bpf_sub_dir, "%s%s/", base, name);
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ goto out;
+ }
ret = mkdir(bpf_sub_dir, S_IRWXU);
if (ret && errno != EEXIST) {
fprintf(stderr, "mkdir %s failed: %s\n", bpf_sub_dir,
strerror(errno));
- return ret;
+ goto out;
}
- return bpf_gen_global(bpf_sub_dir);
+ ret = bpf_gen_global(bpf_sub_dir);
+out:
+ free(bpf_sub_dir);
+ return ret;
}
static int bpf_slave_via_bind_mnt(const char *full_name,
@@ -692,13 +720,22 @@ static int bpf_slave_via_bind_mnt(const char *full_name,
static int bpf_gen_slave(const char *base, const char *name,
const char *link)
{
- char bpf_lnk_dir[PATH_MAX + NAME_MAX + 1];
- char bpf_sub_dir[PATH_MAX + NAME_MAX];
+ char *bpf_lnk_dir = NULL;
+ char *bpf_sub_dir = NULL;
struct stat sb = {};
int ret;
- snprintf(bpf_lnk_dir, sizeof(bpf_lnk_dir), "%s%s/", base, link);
- snprintf(bpf_sub_dir, sizeof(bpf_sub_dir), "%s%s", base, name);
+ ret = asprintf(&bpf_lnk_dir, "%s%s/", base, link);
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ goto out;
+ }
+
+ ret = asprintf(&bpf_sub_dir, "%s%s", base, name);
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ goto out;
+ }
ret = symlink(bpf_lnk_dir, bpf_sub_dir);
if (ret) {
@@ -706,25 +743,30 @@ static int bpf_gen_slave(const char *base, const char *name,
if (errno != EPERM) {
fprintf(stderr, "symlink %s failed: %s\n",
bpf_sub_dir, strerror(errno));
- return ret;
+ goto out;
}
- return bpf_slave_via_bind_mnt(bpf_sub_dir,
- bpf_lnk_dir);
+ ret = bpf_slave_via_bind_mnt(bpf_sub_dir, bpf_lnk_dir);
+ goto out;
}
ret = lstat(bpf_sub_dir, &sb);
if (ret) {
fprintf(stderr, "lstat %s failed: %s\n",
bpf_sub_dir, strerror(errno));
- return ret;
+ goto out;
}
- if ((sb.st_mode & S_IFMT) != S_IFLNK)
- return bpf_gen_global(bpf_sub_dir);
+ if ((sb.st_mode & S_IFMT) != S_IFLNK) {
+ ret = bpf_gen_global(bpf_sub_dir);
+ goto out;
+ }
}
- return 0;
+out:
+ free(bpf_lnk_dir);
+ free(bpf_sub_dir);
+ return ret;
}
static int bpf_gen_hierarchy(const char *base)
@@ -742,7 +784,7 @@ static int bpf_gen_hierarchy(const char *base)
static const char *bpf_get_work_dir(enum bpf_prog_type type)
{
static char bpf_tmp[PATH_MAX] = BPF_DIR_MNT;
- static char bpf_wrk_dir[PATH_MAX];
+ static char *bpf_wrk_dir;
static const char *mnt;
static bool bpf_mnt_cached;
const char *mnt_env = getenv(BPF_ENV_MNT);
@@ -781,7 +823,12 @@ static const char *bpf_get_work_dir(enum bpf_prog_type type)
}
}
- snprintf(bpf_wrk_dir, sizeof(bpf_wrk_dir), "%s/", mnt);
+ ret = asprintf(&bpf_wrk_dir, "%s/", mnt);
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ free(bpf_wrk_dir);
+ goto out;
+ }
ret = bpf_gen_hierarchy(bpf_wrk_dir);
if (ret) {
@@ -1438,31 +1485,48 @@ static int bpf_probe_pinned(const char *name, const struct bpf_elf_ctx *ctx,
static int bpf_make_obj_path(const struct bpf_elf_ctx *ctx)
{
- char tmp[PATH_MAX];
+ char *tmp = NULL;
int ret;
- snprintf(tmp, sizeof(tmp), "%s/%s", bpf_get_work_dir(ctx->type),
- ctx->obj_uid);
+ ret = asprintf(&tmp, "%s/%s", bpf_get_work_dir(ctx->type), ctx->obj_uid);
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ goto out;
+ }
ret = mkdir(tmp, S_IRWXU);
if (ret && errno != EEXIST) {
fprintf(stderr, "mkdir %s failed: %s\n", tmp, strerror(errno));
- return ret;
+ goto out;
}
- return 0;
+ ret = 0;
+out:
+ free(tmp);
+ return ret;
}
static int bpf_make_custom_path(const struct bpf_elf_ctx *ctx,
const char *todo)
{
- char tmp[PATH_MAX], rem[PATH_MAX], *sub;
+ char *tmp = NULL;
+ char *rem = NULL;
+ char *sub;
int ret;
- snprintf(tmp, sizeof(tmp), "%s/../", bpf_get_work_dir(ctx->type));
- snprintf(rem, sizeof(rem), "%s/", todo);
- sub = strtok(rem, "/");
+ ret = asprintf(&tmp, "%s/../", bpf_get_work_dir(ctx->type));
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ goto out;
+ }
+ ret = asprintf(&rem, "%s/", todo);
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ goto out;
+ }
+
+ sub = strtok(rem, "/");
while (sub) {
if (strlen(tmp) + strlen(sub) + 2 > PATH_MAX)
return -EINVAL;
@@ -1474,13 +1538,17 @@ static int bpf_make_custom_path(const struct bpf_elf_ctx *ctx,
if (ret && errno != EEXIST) {
fprintf(stderr, "mkdir %s failed: %s\n", tmp,
strerror(errno));
- return ret;
+ goto out;
}
sub = strtok(NULL, "/");
}
- return 0;
+ ret = 0;
+out:
+ free(rem);
+ free(tmp);
+ return ret;
}
static int bpf_place_pinned(int fd, const char *name,
@@ -2581,14 +2649,23 @@ struct bpf_jited_aux {
static int bpf_derive_prog_from_fdinfo(int fd, struct bpf_prog_data *prog)
{
- char file[PATH_MAX], buff[4096];
+ char *file = NULL;
+ char buff[4096];
unsigned int val;
FILE *fp;
+ int ret;
+
+ ret = asprintf(&file, "/proc/%d/fdinfo/%d", getpid(), fd);
+ if (ret < 0) {
+ fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
+ free(file);
+ return ret;
+ }
- snprintf(file, sizeof(file), "/proc/%d/fdinfo/%d", getpid(), fd);
memset(prog, 0, sizeof(*prog));
fp = fopen(file, "r");
+ free(file);
if (!fp) {
fprintf(stderr, "No procfs support?!\n");
return -EIO;
--
2.21.0
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