tools: bpftool: fix crash with un-owned prog arrays

Prog arrays don't have 'owner_prog_type' and 'owner_jited'
fields in their fdinfo when they are created.  Those fields
are set and reported when first program is checked for
compatibility by bpf_prog_array_compatible().

This means that bpftool cannot expect the fields to always
be there.  Currently trying to show maps on a system with
an un-owned prog array leads to a crash:

$ bpftool map show
389: prog_array  name tail_call_map  flags 0x0
Error: key 'owner_prog_type' not found in fdinfo
Error: key 'owner_jited' not found in fdinfo
       key 4B  value 4B  max_entries 4  memlock 4096B
       Segmentation fault (core dumped)

We pass a NULL pointer to atoi().

Remove the assumption that fdinfo keys are always present.
Add missing validations and remove the p_err() calls which
may lead to broken JSON output as caller will not propagate
the failure.

Fixes: 99a44bef5870 ("tools: bpftool: add owner_prog_type and owner_jited to bpftool output")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

2 files changed, 9 insertions, 14 deletions

diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index 897483457bf0..f7261fad45c1 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -297,10 +297,8 @@ char *get_fdinfo(int fd, const char *key)
         snprintf(path, sizeof(path), "/proc/self/fdinfo/%d", fd);
 
         fdi = fopen(path, "r");
-        if (!fdi) {
-                p_err("can't open fdinfo: %s", strerror(errno));
+        if (!fdi)
                 return NULL;
-        }
 
         while ((n = getline(&line, &line_n, fdi)) > 0) {
                 char *value;
@@ -313,7 +311,6 @@ char *get_fdinfo(int fd, const char *key)
 
                 value = strchr(line, '\t');
                 if (!value || !value[1]) {
-                        p_err("malformed fdinfo!?");
                         free(line);
                         return NULL;
                 }
@@ -326,7 +323,6 @@ char *get_fdinfo(int fd, const char *key)
                 return line;
         }
 
-        p_err("key '%s' not found in fdinfo", key);
         free(line);
         fclose(fdi);
         return NULL;
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 29a3468c6cf6..1ef1ee2280a2 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -513,10 +513,9 @@ static int show_map_close_json(int fd, struct bpf_map_info *info)
                                 jsonw_uint_field(json_wtr, "owner_prog_type",
                                                  prog_type);
                 }
-                if (atoi(owner_jited))
-                        jsonw_bool_field(json_wtr, "owner_jited", true);
-                else
-                        jsonw_bool_field(json_wtr, "owner_jited", false);
+                if (owner_jited)
+                        jsonw_bool_field(json_wtr, "owner_jited",
+                                         !!atoi(owner_jited));
 
                 free(owner_prog_type);
                 free(owner_jited);
@@ -569,7 +568,8 @@ static int show_map_close_plain(int fd, struct bpf_map_info *info)
                 char *owner_prog_type = get_fdinfo(fd, "owner_prog_type");
                 char *owner_jited = get_fdinfo(fd, "owner_jited");
 
-                printf("\n\t");
+                if (owner_prog_type || owner_jited)
+                        printf("\n\t");
                 if (owner_prog_type) {
                         unsigned int prog_type = atoi(owner_prog_type);
 
@@ -579,10 +579,9 @@ static int show_map_close_plain(int fd, struct bpf_map_info *info)
                         else
                                 printf("owner_prog_type %d  ", prog_type);
                 }
-                if (atoi(owner_jited))
-                        printf("owner jited");
-                else
-                        printf("owner not jited");
+                if (owner_jited)
+                        printf("owner%s jited",
+                               atoi(owner_jited) ? "" : " not");
 
                 free(owner_prog_type);
                 free(owner_jited);