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bpftool: Explicit errno handling in skeletons

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Andrii noticed that since f97b8b9bd6 ("bpftool: Fix a bug in subskeleton
code generation") the subskeleton code allows bpf_object__destroy_subskeleton
to overwrite the errno that subskeleton__open would return with. While this
is not currently an issue, let's make it future-proof.

This patch explicitly tracks err in subskeleton__open and skeleton__create
(i.e. calloc failure is explicitly ENOMEM) and ensures that errno is -err on
the error return path. The skeleton code had to be changed since maps and
progs codegen is shared with subskeletons.

Fixes: f97b8b9bd6 ("bpftool: Fix a bug in subskeleton code generation")
Signed-off-by: Delyan Kratunov <delyank@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/3b6bfbb770c79ae64d8de26c1c1bd9d53a4b85f8.camel@fb.com
This commit is contained in:
Delyan Kratunov 2022-03-21 23:29:18 +00:00 committed by Daniel Borkmann
parent 77c9387c0c
commit 522574fd78
1 changed files with 15 additions and 7 deletions
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22
tools/bpf/bpftool/gen.c
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@ -828,8 +828,10 @@ codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped)
s->map_cnt = %zu; \n\
s->map_skel_sz = sizeof(*s->maps); \n\
s->maps = (struct bpf_map_skeleton *)calloc(s->map_cnt, s->map_skel_sz);\n\
if (!s->maps) \n\
if (!s->maps) { \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
",
map_cnt
);
@ -870,8 +872,10 @@ codegen_progs_skeleton(struct bpf_object *obj, size_t prog_cnt, bool populate_li
s->prog_cnt = %zu; \n\
s->prog_skel_sz = sizeof(*s->progs); \n\
s->progs = (struct bpf_prog_skeleton *)calloc(s->prog_cnt, s->prog_skel_sz);\n\
if (!s->progs) \n\
if (!s->progs) { \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
",
prog_cnt
);
@ -1182,10 +1186,13 @@ static int do_skeleton(int argc, char **argv)
%1$s__create_skeleton(struct %1$s *obj) \n\
{ \n\
struct bpf_object_skeleton *s; \n\
int err; \n\
\n\
s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
if (!s) \n\
if (!s) { \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
\n\
s->sz = sizeof(*s); \n\
s->name = \"%1$s\"; \n\
@ -1206,7 +1213,7 @@ static int do_skeleton(int argc, char **argv)
return 0; \n\
err: \n\
bpf_object__destroy_skeleton(s); \n\
return -ENOMEM; \n\
return err; \n\
} \n\
\n\
static inline const void *%2$s__elf_bytes(size_t *sz) \n\
@ -1466,12 +1473,12 @@ static int do_subskeleton(int argc, char **argv)
\n\
obj = (struct %1$s *)calloc(1, sizeof(*obj)); \n\
if (!obj) { \n\
errno = ENOMEM; \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
s = (struct bpf_object_subskeleton *)calloc(1, sizeof(*s));\n\
if (!s) { \n\
errno = ENOMEM; \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
s->sz = sizeof(*s); \n\
@ -1483,7 +1490,7 @@ static int do_subskeleton(int argc, char **argv)
s->var_cnt = %2$d; \n\
s->vars = (struct bpf_var_skeleton *)calloc(%2$d, sizeof(*s->vars));\n\
if (!s->vars) { \n\
errno = ENOMEM; \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
",
@ -1538,6 +1545,7 @@ static int do_subskeleton(int argc, char **argv)
return obj; \n\
err: \n\
%1$s__destroy(obj); \n\
errno = -err; \n\
return NULL; \n\
} \n\
\n\