This command allows comparing the underling private data of two fds. This
is useful e.g. to find out if a seccomp filter is inherited, since struct
seccomp_filter are unique across tasks and are the private_data seccomp
fds.
Signed-off-by: Tycho Andersen <tycho.andersen@xxxxxxxxxxxxx>
CC: Kees Cook <keescook@xxxxxxxxxxxx>
CC: Will Drewry <wad@xxxxxxxxxxxx>
CC: Oleg Nesterov <oleg@xxxxxxxxxx>
CC: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
CC: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
CC: Serge E. Hallyn <serge.hallyn@xxxxxxxxxx>
CC: Alexei Starovoitov <ast@xxxxxxxxxx>
CC: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
---
include/uapi/linux/kcmp.h | 1 +
kernel/kcmp.c | 14 ++++++++++++++
2 files changed, 15 insertions(+)
diff --git a/include/uapi/linux/kcmp.h b/include/uapi/linux/kcmp.h
index 84df14b..ed389d2 100644
--- a/include/uapi/linux/kcmp.h
+++ b/include/uapi/linux/kcmp.h
@@ -10,6 +10,7 @@ enum kcmp_type {
KCMP_SIGHAND,
KCMP_IO,
KCMP_SYSVSEM,
+ KCMP_FILE_PRIVATE_DATA,
KCMP_TYPES,
};
diff --git a/kernel/kcmp.c b/kernel/kcmp.c
index 0aa69ea..9ae673b 100644
--- a/kernel/kcmp.c
+++ b/kernel/kcmp.c
@@ -165,6 +165,20 @@ SYSCALL_DEFINE5(kcmp, pid_t, pid1, pid_t, pid2, int, type,
ret = -EOPNOTSUPP;
#endif
break;
+ case KCMP_FILE_PRIVATE_DATA: {
+ struct file *filp1, *filp2;
+
+ filp1 = get_file_raw_ptr(task1, idx1);
+ filp2 = get_file_raw_ptr(task2, idx2);
+
+ if (filp1 && filp2)
+ ret = kcmp_ptr(filp1->private_data,
+ filp2->private_data,
+ KCMP_FILE_PRIVATE_DATA);
+ else
+ ret = -EBADF;
+ break;
+ }
default:
ret = -EINVAL;
break;
--
2.5.0
--
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