]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commit
bpf: fix uapi hole for 32 bit compat applications
authorDaniel Borkmann <daniel@iogearbox.net>
Sat, 2 Jun 2018 03:21:59 +0000 (05:21 +0200)
committerAlexei Starovoitov <ast@kernel.org>
Sat, 2 Jun 2018 03:41:35 +0000 (20:41 -0700)
commit36f9814a494a874d5a0f44843544b4b2539022db
treef70e8f924bf1ff9de0ac3892f5b0044f30495624
parent8005b09d99fac78e6f5fb9da30b5ae94840af03b
bpf: fix uapi hole for 32 bit compat applications

In 64 bit, we have a 4 byte hole between ifindex and netns_dev in the
case of struct bpf_map_info but also struct bpf_prog_info. In net-next
commit b85fab0e67b ("bpf: Add gpl_compatible flag to struct bpf_prog_info")
added a bitfield into it to expose some flags related to programs. Thus,
add an unnamed __u32 bitfield for both so that alignment keeps the same
in both 32 and 64 bit cases, and can be naturally extended from there
as in b85fab0e67b.

Before:

  # file test.o
  test.o: ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped
  # pahole test.o
  struct bpf_map_info {
__u32                      type;                 /*     0     4 */
__u32                      id;                   /*     4     4 */
__u32                      key_size;             /*     8     4 */
__u32                      value_size;           /*    12     4 */
__u32                      max_entries;          /*    16     4 */
__u32                      map_flags;            /*    20     4 */
char                       name[16];             /*    24    16 */
__u32                      ifindex;              /*    40     4 */
__u64                      netns_dev;            /*    44     8 */
__u64                      netns_ino;            /*    52     8 */

/* size: 64, cachelines: 1, members: 10 */
/* padding: 4 */
  };

After (same as on 64 bit):

  # file test.o
  test.o: ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped
  # pahole test.o
  struct bpf_map_info {
__u32                      type;                 /*     0     4 */
__u32                      id;                   /*     4     4 */
__u32                      key_size;             /*     8     4 */
__u32                      value_size;           /*    12     4 */
__u32                      max_entries;          /*    16     4 */
__u32                      map_flags;            /*    20     4 */
char                       name[16];             /*    24    16 */
__u32                      ifindex;              /*    40     4 */

/* XXX 4 bytes hole, try to pack */

__u64                      netns_dev;            /*    48     8 */
__u64                      netns_ino;            /*    56     8 */
/* --- cacheline 1 boundary (64 bytes) --- */

/* size: 64, cachelines: 1, members: 10 */
/* sum members: 60, holes: 1, sum holes: 4 */
  };

Reported-by: Dmitry V. Levin <ldv@altlinux.org>
Reported-by: Eugene Syromiatnikov <esyr@redhat.com>
Fixes: 52775b33bb507 ("bpf: offload: report device information about offloaded maps")
Fixes: 675fc275a3a2d ("bpf: offload: report device information for offloaded programs")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
include/uapi/linux/bpf.h
tools/include/uapi/linux/bpf.h