Function open_obj_pinned() prints error messages when it fails to open a
link in the BPF virtual file system. However, in some occasions it is
not desirable to print an error, for example when we parse all links
under the bpffs root, and the error is due to some paths actually being
symbolic links.
Example output:
# ls -l /sys/fs/bpf/
lrwxrwxrwx 1 root root 0 Oct 18 19:00 ip -> /sys/fs/bpf/tc/
drwx------ 3 root root 0 Oct 18 19:00 tc
lrwxrwxrwx 1 root root 0 Oct 18 19:00 xdp -> /sys/fs/bpf/tc/
# bpftool --bpffs prog show
Error: bpf obj get (/sys/fs/bpf): Permission denied
Error: bpf obj get (/sys/fs/bpf): Permission denied
# strace -e bpf bpftool --bpffs prog show
bpf(BPF_OBJ_GET, {pathname="/sys/fs/bpf/ip", bpf_fd=0}, 72) = -1 EACCES (Permission denied)
Error: bpf obj get (/sys/fs/bpf): Permission denied
bpf(BPF_OBJ_GET, {pathname="/sys/fs/bpf/xdp", bpf_fd=0}, 72) = -1 EACCES (Permission denied)
Error: bpf obj get (/sys/fs/bpf): Permission denied
...
To fix it, pass a bool as a second argument to the function, and prevent
it from printing an error when the argument is set to true.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
f120919f99