We need a direct method of getting the pid inside containers.
If some issues occurred inside container guest, host user
could not know which process is in trouble just by guest pid:
the users of container guest only knew the pid inside containers.
This will bring obstacle for trouble shooting.
int getnspid(pid_t pid, int fd1, int fd2);
pid: the pid number need to be translated.
fd: a file descriptor referring to one of
the namespace entries in a /proc/[pid]/ns/pid.
fd1 for destination ns(ns1), where the pid came from.
fd2 for reference ns(ns2), while fd2 = -2 means for current ns.
return value:
>0 : translated pid in ns1(fd1) seen from ns2(fd2).
<=0: on failure.
Signed-off-by: Chen Hanxiao <chenhanx...@cn.fujitsu.com>
---
v2: drop pidtype
check ns_ops before getting pid_namespace structure
arch/x86/syscalls/syscall_32.tbl | 1 +
arch/x86/syscalls/syscall_64.tbl | 1 +
include/linux/syscalls.h | 1 +
kernel/nsproxy.c | 45 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 48 insertions(+)
diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
index d6b8679..9de0b32 100644
--- a/arch/x86/syscalls/syscall_32.tbl
+++ b/arch/x86/syscalls/syscall_32.tbl
@@ -360,3 +360,4 @@
351 i386 sched_setattr sys_sched_setattr
352 i386 sched_getattr sys_sched_getattr
353 i386 renameat2 sys_renameat2
+354 i386 getnspid sys_getnspid
diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
index ec255a1..1630a8a 100644
--- a/arch/x86/syscalls/syscall_64.tbl
+++ b/arch/x86/syscalls/syscall_64.tbl
@@ -323,6 +323,7 @@
314 common sched_setattr sys_sched_setattr
315 common sched_getattr sys_sched_getattr
316 common renameat2 sys_renameat2
+317 common getnspid sys_getnspid
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index b0881a0..53dd0e8 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -866,4 +866,5 @@ asmlinkage long sys_process_vm_writev(pid_t pid,
asmlinkage long sys_kcmp(pid_t pid1, pid_t pid2, int type,
unsigned long idx1, unsigned long idx2);
asmlinkage long sys_finit_module(int fd, const char __user *uargs, int flags);
+asmlinkage long sys_getpidns(pid_t pid, int fd1, int fd2);
#endif
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 8e78110..9701ade 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -261,6 +261,51 @@ out:
return err;
}
+SYSCALL_DEFINE3(getnspid, pid_t, pid, int, fd1, int, fd2)
+{
+ struct file *file1 = NULL, *file2 = NULL;
+ struct pid *pid_struct;
+ struct pid_namespace *ns1, *ns2;
+ struct proc_ns *ei;
+ int ret = -EINVAL;
+
+ file1 = proc_ns_fget(fd1);
+ if (IS_ERR(file1))
+ return PTR_ERR(file1);
+ ei = get_proc_ns(file_inode(file1));
+ if (ei->ns_ops != &pidns_operations)
+ goto out;
+ ns1 = (struct pid_namespace *)ei->ns;
+
+ /* fd == -2 for current pid ns */
+ if (fd2 == -2) {
+ ns2 = task_active_pid_ns(current);
+ } else {
+ file2 = proc_ns_fget(fd2);
+ if (IS_ERR(file2)) {
+ fput(file1);
+ return PTR_ERR(file2);
+ }
+ ei = get_proc_ns(file_inode(file2));
+ if (ei->ns_ops != &pidns_operations)
+ goto out;
+ ns2 = (struct pid_namespace *)ei->ns;
+ }
+
+ pid_struct = find_pid_ns(pid, ns1);
+ if (!pid_struct) {
+ ret = -ESRCH;
+ goto out;
+ }
+
+ ret = pid_nr_ns(pid_struct, ns2);
+out:
+ fput(file1);
+ if (file2)
+ fput(file2);
+ return ret;
+}
+
int __init nsproxy_cache_init(void)
{
nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
--
1.9.0
--
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