On Thu, May 30, 2024 at 1:57 AM Lennart Poettering <lennart@xxxxxxxxxxxxxx> wrote: > > On Mi, 29.05.24 15:32, Andrii Nakryiko (andrii@xxxxxxxxxx) wrote: > > > Make sure to preserve and/or enforce FD_CLOEXEC flag on duped FDs. > > Use dup3() with O_CLOEXEC flag for that. > > > > Without this fix libbpf effectively clears FD_CLOEXEC flag on each of BPF > > map/prog FD, which is definitely not the right or expected behavior. > > Thanks! > > lgtm, superficially. This is now in libbpf v1.4.3 bug fix release ([0]) [0] https://github.com/libbpf/libbpf/releases/tag/v1.4.3 > > > Reported-by: Lennart Poettering <lennart@xxxxxxxxxxxxxx> > > Fixes: bc308d011ab8 ("libbpf: call dup2() syscall directly") > > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > --- > > tools/lib/bpf/libbpf_internal.h | 10 +++------- > > 1 file changed, 3 insertions(+), 7 deletions(-) > > > > diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h > > index a0dcfb82e455..7e7e686008c6 100644 > > --- a/tools/lib/bpf/libbpf_internal.h > > +++ b/tools/lib/bpf/libbpf_internal.h > > @@ -597,13 +597,9 @@ static inline int ensure_good_fd(int fd) > > return fd; > > } > > > > -static inline int sys_dup2(int oldfd, int newfd) > > +static inline int sys_dup3(int oldfd, int newfd, int flags) > > { > > -#ifdef __NR_dup2 > > - return syscall(__NR_dup2, oldfd, newfd); > > -#else > > - return syscall(__NR_dup3, oldfd, newfd, 0); > > -#endif > > + return syscall(__NR_dup3, oldfd, newfd, flags); > > } > > > > /* Point *fixed_fd* to the same file that *tmp_fd* points to. > > @@ -614,7 +610,7 @@ static inline int reuse_fd(int fixed_fd, int tmp_fd) > > { > > int err; > > > > - err = sys_dup2(tmp_fd, fixed_fd); > > + err = sys_dup3(tmp_fd, fixed_fd, O_CLOEXEC); > > err = err < 0 ? -errno : 0; > > close(tmp_fd); /* clean up temporary FD */ > > return err; > > -- > > 2.43.0 > > > > > > Lennart > > -- > Lennart Poettering, Berlin
