On Mon, Aug 15, 2022 at 8:36 AM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote:
>
> On 13/08/2022 01:09, Hangbin Liu wrote:
> > Similar with commit 10b62d6a38f7 ("libbpf: Add names for auxiliary maps"),
> > let's make bpf_prog_load() also ignore name if kernel doesn't support
> > program name.
> >
> > To achieve this, we need to call sys_bpf_prog_load() directly in
> > probe_kern_prog_name() to avoid circular dependency. sys_bpf_prog_load()
> > also need to be exported in the libbpf_internal.h file.
> >
> > Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
> > ---
> > v2: move sys_bpf_prog_load definition to libbpf_internal.h. memset attr
> > to 0 specifically to aviod padding.
> > ---
> > tools/lib/bpf/bpf.c | 6 ++----
> > tools/lib/bpf/libbpf.c | 12 ++++++++++--
> > tools/lib/bpf/libbpf_internal.h | 3 +++
> > 3 files changed, 15 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> > index 6a96e665dc5d..575867d69496 100644
> > --- a/tools/lib/bpf/bpf.c
> > +++ b/tools/lib/bpf/bpf.c
> > @@ -84,9 +84,7 @@ static inline int sys_bpf_fd(enum bpf_cmd cmd, union bpf_attr *attr,
> > return ensure_good_fd(fd);
> > }
> >
> > -#define PROG_LOAD_ATTEMPTS 5
> > -
> > -static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)
> > +int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)
> > {
> > int fd;
> >
> > @@ -263,7 +261,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
> > attr.prog_ifindex = OPTS_GET(opts, prog_ifindex, 0);
> > attr.kern_version = OPTS_GET(opts, kern_version, 0);
> >
> > - if (prog_name)
> > + if (prog_name && kernel_supports(NULL, FEAT_PROG_NAME))
> > libbpf_strlcpy(attr.prog_name, prog_name, sizeof(attr.prog_name));
> > attr.license = ptr_to_u64(license);
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index 3f01f5cd8a4c..4a351897bdcc 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -4419,10 +4419,18 @@ static int probe_kern_prog_name(void)
> > BPF_MOV64_IMM(BPF_REG_0, 0),
> > BPF_EXIT_INSN(),
> > };
> > - int ret, insn_cnt = ARRAY_SIZE(insns);
> > + union bpf_attr attr;
> > + int ret;
> > +
> > + memset(&attr, 0, sizeof(attr));
> > + attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
> > + attr.license = ptr_to_u64("GPL");
> > + attr.insns = ptr_to_u64(insns);
> > + attr.insn_cnt = (__u32)ARRAY_SIZE(insns);
> > + libbpf_strlcpy(attr.prog_name, "test", sizeof(attr.prog_name));
> >
> > /* make sure loading with name works */
> > - ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "test", "GPL", insns, insn_cnt, NULL);
> > + ret = sys_bpf_prog_load(&attr, sizeof(attr), PROG_LOAD_ATTEMPTS);
> > return probe_fd(ret);
> > }
> >
> > diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
> > index 4135ae0a2bc3..377642ff51fc 100644
> > --- a/tools/lib/bpf/libbpf_internal.h
> > +++ b/tools/lib/bpf/libbpf_internal.h
> > @@ -573,4 +573,7 @@ static inline bool is_pow_of_2(size_t x)
> > return x && (x & (x - 1)) == 0;
> > }
> >
> > +#define PROG_LOAD_ATTEMPTS 5
> > +int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts);
> > +
> > #endif /* __LIBBPF_LIBBPF_INTERNAL_H */
>
> Looks good to me, thanks!
>
> Acked-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
I did a small adjustment to not fill out entire big bpf_attr union
completely (and added a bit more meaningful "libbpf_nametest" prog
name):
$ git diff --staged
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 4a351897bdcc..f05dd61a8a7f 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4415,6 +4415,7 @@ static int probe_fd(int fd)
static int probe_kern_prog_name(void)
{
+ const size_t attr_sz = offsetofend(union bpf_attr, prog_name);
struct bpf_insn insns[] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
@@ -4422,12 +4423,12 @@ static int probe_kern_prog_name(void)
union bpf_attr attr;
int ret;
- memset(&attr, 0, sizeof(attr));
+ memset(&attr, 0, attr_sz);
attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
attr.license = ptr_to_u64("GPL");
attr.insns = ptr_to_u64(insns);
attr.insn_cnt = (__u32)ARRAY_SIZE(insns);
- libbpf_strlcpy(attr.prog_name, "test", sizeof(attr.prog_name));
+ libbpf_strlcpy(attr.prog_name, "libbpf_nametest",
sizeof(attr.prog_name));
Pushed to bpf-next, thanks!
