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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: e42256699c ("bpf: make tc's bpf loader generic and move into lib")
Signed-off-by: Andrea Claudi <aclaudi@redhat.com>
Signed-off-by: David Ahern <dsahern@gmail.com>
This commit is contained in:
Andrea Claudi
David Ahern
parent
9b13cddfe2
commit
c0325b0638
155
lib/bpf.c
155
lib/bpf.c
@ -406,13 +406,21 @@ static int bpf_derive_elf_map_from_fdinfo(int fd, struct bpf_elf_map *map,
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struct bpf_map_ext *ext)
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{
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unsigned int val, owner_type = 0, owner_jited = 0;
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char file[PATH_MAX], buff[4096];
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char *file = NULL;
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char buff[4096];
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FILE *fp;
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int ret;
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snprintf(file, sizeof(file), "/proc/%d/fdinfo/%d", getpid(), fd);
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ret = asprintf(&file, "/proc/%d/fdinfo/%d", getpid(), fd);
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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free(file);
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return ret;
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}
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memset(map, 0, sizeof(*map));
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fp = fopen(file, "r");
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free(file);
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if (!fp) {
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fprintf(stderr, "No procfs support?!\n");
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return -EIO;
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@ -600,8 +608,9 @@ int bpf_trace_pipe(void)
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0,
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};
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int fd_in, fd_out = STDERR_FILENO;
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char tpipe[PATH_MAX];
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char *tpipe = NULL;
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const char *mnt;
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int ret;
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mnt = bpf_find_mntpt("tracefs", TRACEFS_MAGIC, tracefs_mnt,
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sizeof(tracefs_mnt), tracefs_known_mnts);
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@ -610,9 +619,15 @@ int bpf_trace_pipe(void)
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return -1;
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}
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snprintf(tpipe, sizeof(tpipe), "%s/trace_pipe", mnt);
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ret = asprintf(&tpipe, "%s/trace_pipe", mnt);
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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free(tpipe);
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return ret;
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}
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fd_in = open(tpipe, O_RDONLY);
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free(tpipe);
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if (fd_in < 0)
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return -1;
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@ -633,37 +648,50 @@ int bpf_trace_pipe(void)
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static int bpf_gen_global(const char *bpf_sub_dir)
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{
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char bpf_glo_dir[PATH_MAX];
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char *bpf_glo_dir = NULL;
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int ret;
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snprintf(bpf_glo_dir, sizeof(bpf_glo_dir), "%s/%s/",
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bpf_sub_dir, BPF_DIR_GLOBALS);
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ret = asprintf(&bpf_glo_dir, "%s/%s/", bpf_sub_dir, BPF_DIR_GLOBALS);
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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goto out;
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}
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ret = mkdir(bpf_glo_dir, S_IRWXU);
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if (ret && errno != EEXIST) {
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fprintf(stderr, "mkdir %s failed: %s\n", bpf_glo_dir,
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strerror(errno));
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return ret;
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goto out;
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}
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return 0;
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ret = 0;
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out:
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free(bpf_glo_dir);
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return ret;
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}
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static int bpf_gen_master(const char *base, const char *name)
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{
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char bpf_sub_dir[PATH_MAX + NAME_MAX + 1];
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char *bpf_sub_dir = NULL;
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int ret;
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snprintf(bpf_sub_dir, sizeof(bpf_sub_dir), "%s%s/", base, name);
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ret = asprintf(&bpf_sub_dir, "%s%s/", base, name);
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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goto out;
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}
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ret = mkdir(bpf_sub_dir, S_IRWXU);
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if (ret && errno != EEXIST) {
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fprintf(stderr, "mkdir %s failed: %s\n", bpf_sub_dir,
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strerror(errno));
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return ret;
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goto out;
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}
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return bpf_gen_global(bpf_sub_dir);
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ret = bpf_gen_global(bpf_sub_dir);
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out:
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free(bpf_sub_dir);
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return ret;
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}
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static int bpf_slave_via_bind_mnt(const char *full_name,
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@ -692,13 +720,22 @@ static int bpf_slave_via_bind_mnt(const char *full_name,
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static int bpf_gen_slave(const char *base, const char *name,
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const char *link)
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{
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char bpf_lnk_dir[PATH_MAX + NAME_MAX + 1];
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char bpf_sub_dir[PATH_MAX + NAME_MAX];
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char *bpf_lnk_dir = NULL;
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char *bpf_sub_dir = NULL;
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struct stat sb = {};
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int ret;
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snprintf(bpf_lnk_dir, sizeof(bpf_lnk_dir), "%s%s/", base, link);
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snprintf(bpf_sub_dir, sizeof(bpf_sub_dir), "%s%s", base, name);
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ret = asprintf(&bpf_lnk_dir, "%s%s/", base, link);
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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goto out;
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}
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ret = asprintf(&bpf_sub_dir, "%s%s", base, name);
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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goto out;
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}
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ret = symlink(bpf_lnk_dir, bpf_sub_dir);
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if (ret) {
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@ -706,25 +743,30 @@ static int bpf_gen_slave(const char *base, const char *name,
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if (errno != EPERM) {
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fprintf(stderr, "symlink %s failed: %s\n",
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bpf_sub_dir, strerror(errno));
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return ret;
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goto out;
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}
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return bpf_slave_via_bind_mnt(bpf_sub_dir,
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bpf_lnk_dir);
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ret = bpf_slave_via_bind_mnt(bpf_sub_dir, bpf_lnk_dir);
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goto out;
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}
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ret = lstat(bpf_sub_dir, &sb);
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if (ret) {
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fprintf(stderr, "lstat %s failed: %s\n",
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bpf_sub_dir, strerror(errno));
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return ret;
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goto out;
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}
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if ((sb.st_mode & S_IFMT) != S_IFLNK)
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return bpf_gen_global(bpf_sub_dir);
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if ((sb.st_mode & S_IFMT) != S_IFLNK) {
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ret = bpf_gen_global(bpf_sub_dir);
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goto out;
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}
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}
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return 0;
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out:
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free(bpf_lnk_dir);
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free(bpf_sub_dir);
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return ret;
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}
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static int bpf_gen_hierarchy(const char *base)
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@ -742,7 +784,7 @@ static int bpf_gen_hierarchy(const char *base)
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static const char *bpf_get_work_dir(enum bpf_prog_type type)
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{
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static char bpf_tmp[PATH_MAX] = BPF_DIR_MNT;
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static char bpf_wrk_dir[PATH_MAX];
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static char *bpf_wrk_dir;
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static const char *mnt;
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static bool bpf_mnt_cached;
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const char *mnt_env = getenv(BPF_ENV_MNT);
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@ -781,7 +823,12 @@ static const char *bpf_get_work_dir(enum bpf_prog_type type)
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}
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}
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snprintf(bpf_wrk_dir, sizeof(bpf_wrk_dir), "%s/", mnt);
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ret = asprintf(&bpf_wrk_dir, "%s/", mnt);
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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free(bpf_wrk_dir);
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goto out;
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}
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ret = bpf_gen_hierarchy(bpf_wrk_dir);
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if (ret) {
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@ -1438,31 +1485,48 @@ static int bpf_probe_pinned(const char *name, const struct bpf_elf_ctx *ctx,
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static int bpf_make_obj_path(const struct bpf_elf_ctx *ctx)
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{
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char tmp[PATH_MAX];
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char *tmp = NULL;
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int ret;
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snprintf(tmp, sizeof(tmp), "%s/%s", bpf_get_work_dir(ctx->type),
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ctx->obj_uid);
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ret = asprintf(&tmp, "%s/%s", bpf_get_work_dir(ctx->type), ctx->obj_uid);
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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goto out;
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}
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ret = mkdir(tmp, S_IRWXU);
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if (ret && errno != EEXIST) {
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fprintf(stderr, "mkdir %s failed: %s\n", tmp, strerror(errno));
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return ret;
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goto out;
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}
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return 0;
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ret = 0;
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out:
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free(tmp);
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return ret;
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}
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static int bpf_make_custom_path(const struct bpf_elf_ctx *ctx,
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const char *todo)
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{
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char tmp[PATH_MAX], rem[PATH_MAX], *sub;
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char *tmp = NULL;
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char *rem = NULL;
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char *sub;
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int ret;
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snprintf(tmp, sizeof(tmp), "%s/../", bpf_get_work_dir(ctx->type));
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snprintf(rem, sizeof(rem), "%s/", todo);
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sub = strtok(rem, "/");
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ret = asprintf(&tmp, "%s/../", bpf_get_work_dir(ctx->type));
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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goto out;
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}
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ret = asprintf(&rem, "%s/", todo);
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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goto out;
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}
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sub = strtok(rem, "/");
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while (sub) {
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if (strlen(tmp) + strlen(sub) + 2 > PATH_MAX)
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return -EINVAL;
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@ -1474,13 +1538,17 @@ static int bpf_make_custom_path(const struct bpf_elf_ctx *ctx,
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if (ret && errno != EEXIST) {
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fprintf(stderr, "mkdir %s failed: %s\n", tmp,
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strerror(errno));
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return ret;
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goto out;
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}
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sub = strtok(NULL, "/");
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}
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return 0;
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ret = 0;
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out:
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free(rem);
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free(tmp);
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return ret;
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}
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static int bpf_place_pinned(int fd, const char *name,
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@ -2581,14 +2649,23 @@ struct bpf_jited_aux {
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static int bpf_derive_prog_from_fdinfo(int fd, struct bpf_prog_data *prog)
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{
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char file[PATH_MAX], buff[4096];
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char *file = NULL;
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char buff[4096];
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unsigned int val;
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FILE *fp;
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int ret;
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ret = asprintf(&file, "/proc/%d/fdinfo/%d", getpid(), fd);
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if (ret < 0) {
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fprintf(stderr, "asprintf failed: %s\n", strerror(errno));
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free(file);
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return ret;
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}
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snprintf(file, sizeof(file), "/proc/%d/fdinfo/%d", getpid(), fd);
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memset(prog, 0, sizeof(*prog));
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fp = fopen(file, "r");
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free(file);
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if (!fp) {
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fprintf(stderr, "No procfs support?!\n");
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return -EIO;
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