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Message-ID: <20190808203230.rj4wthhjlk3zwrhw@dev00>
Date: Thu, 8 Aug 2019 16:32:32 -0400
From: Carlos Antonio Neira Bustos <cneirabustos@...il.com>
To: Y Song <ys114321@...il.com>
Cc: Yonghong Song <yhs@...com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"ebiederm@...ssion.com" <ebiederm@...ssion.com>,
"brouer@...hat.com" <brouer@...hat.com>,
"quentin.monnet@...ronome.com" <quentin.monnet@...ronome.com>
Subject: Re: [PATCH v5 bpf-next] BPF: helpers: New helper to obtain namespace
data from current task
Hi Yonghong,
I'm sorry just to be sure, I'm just missing the error codes from filename_lookup()?.
I'll work on that.
Bests
> > > Maybe reword by following the code sequence.
> > > if *size_of_pidns* is not valid or unable to get ns, pid or tgid of
> > > the current task.
> > >
> > > > + *
> > > > + * **-ENOMEM** if allocation fails.
> > >
> > > Maybe some other error codes in filename_lookup() function?
> > >
> > > > + *
> > > > + * If unable to get the inode from /proc/self/ns/pid an error code
> > > > + * will be returned.
> > >
> > > You do not need this. The description of error code cases should cover this.
>
On Thu, Aug 08, 2019 at 12:44:22PM -0700, Y Song wrote:
> On Thu, Aug 8, 2019 at 10:52 AM Carlos Antonio Neira Bustos
> <cneirabustos@...il.com> wrote:
> >
> > Yonghong,
> >
> > I have modified the patch following your feedback.
> > Let me know if I'm missing something.
>
> Yes, I have some other requests about formating.
> https://lore.kernel.org/netdev/20190808174848.poybtaagg5ctle7t@dev00/T/#t
> Could you address it as well?
>
> >
> > Bests
> >
> > From 70f8d5584700c9cfc82c006901d8ee9595c53f15 Mon Sep 17 00:00:00 2001
> > From: Carlos <cneirabustos@...il.com>
> > Date: Wed, 7 Aug 2019 20:04:30 -0400
> > Subject: [PATCH] [PATCH v6 bpf-next] BPF: New helper to obtain namespace data
> > from current task
> >
> > This helper obtains the active namespace from current and returns pid, tgid,
> > device and namespace id as seen from that namespace, allowing to instrument
> > a process inside a container.
> > Device is read from /proc/self/ns/pid, as in the future it's possible that
> > different pid_ns files may belong to different devices, according
> > to the discussion between Eric Biederman and Yonghong in 2017 linux plumbers
> > conference.
> > Currently bpf_get_current_pid_tgid(), is used to do pid filtering in bcc's
> > scripts but this helper returns the pid as seen by the root namespace which is
> > fine when a bcc script is not executed inside a container.
> > When the process of interest is inside a container, pid filtering will not work
> > if bpf_get_current_pid_tgid() is used. This helper addresses this limitation
> > returning the pid as it's seen by the current namespace where the script is
> > executing.
> >
> > This helper has the same use cases as bpf_get_current_pid_tgid() as it can be
> > used to do pid filtering even inside a container.
> >
> > For example a bcc script using bpf_get_current_pid_tgid() (tools/funccount.py):
> >
> > u32 pid = bpf_get_current_pid_tgid() >> 32;
> > if (pid != <pid_arg_passed_in>)
> > return 0;
> > Could be modified to use bpf_get_current_pidns_info() as follows:
> >
> > struct bpf_pidns pidns;
> > bpf_get_current_pidns_info(&pidns, sizeof(struct bpf_pidns));
> > u32 pid = pidns.tgid;
> > u32 nsid = pidns.nsid;
> > if ((pid != <pid_arg_passed_in>) && (nsid != <nsid_arg_passed_in>))
> > return 0;
> >
> > To find out the name PID namespace id of a process, you could use this command:
> >
> > $ ps -h -o pidns -p <pid_of_interest>
> >
> > Or this other command:
> >
> > $ ls -Li /proc/<pid_of_interest>/ns/pid
> >
> > Signed-off-by: Carlos Neira <cneirabustos@...il.com>
> > ---
> > fs/internal.h | 2 -
> > fs/namei.c | 1 -
> > include/linux/bpf.h | 1 +
> > include/linux/namei.h | 4 +
> > include/uapi/linux/bpf.h | 27 +++-
> > kernel/bpf/core.c | 1 +
> > kernel/bpf/helpers.c | 64 ++++++++++
> > kernel/trace/bpf_trace.c | 2 +
> > samples/bpf/Makefile | 3 +
> > samples/bpf/trace_ns_info_user.c | 35 ++++++
> > samples/bpf/trace_ns_info_user_kern.c | 44 +++++++
> > tools/include/uapi/linux/bpf.h | 27 +++-
> > tools/testing/selftests/bpf/Makefile | 2 +-
> > tools/testing/selftests/bpf/bpf_helpers.h | 3 +
> > .../testing/selftests/bpf/progs/test_pidns_kern.c | 51 ++++++++
> > tools/testing/selftests/bpf/test_pidns.c | 138 +++++++++++++++++++++
> > 16 files changed, 399 insertions(+), 6 deletions(-)
> > create mode 100644 samples/bpf/trace_ns_info_user.c
> > create mode 100644 samples/bpf/trace_ns_info_user_kern.c
> > create mode 100644 tools/testing/selftests/bpf/progs/test_pidns_kern.c
> > create mode 100644 tools/testing/selftests/bpf/test_pidns.c
> >
> > diff --git a/fs/internal.h b/fs/internal.h
> > index 315fcd8d237c..6647e15dd419 100644
> > --- a/fs/internal.h
> > +++ b/fs/internal.h
> > @@ -59,8 +59,6 @@ extern int finish_clean_context(struct fs_context *fc);
> > /*
> > * namei.c
> > */
> > -extern int filename_lookup(int dfd, struct filename *name, unsigned flags,
> > - struct path *path, struct path *root);
> > extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
> > extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
> > const char *, unsigned int, struct path *);
> > diff --git a/fs/namei.c b/fs/namei.c
> > index 209c51a5226c..a89fc72a4a10 100644
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@ -19,7 +19,6 @@
> > #include <linux/export.h>
> > #include <linux/kernel.h>
> > #include <linux/slab.h>
> > -#include <linux/fs.h>
> > #include <linux/namei.h>
> > #include <linux/pagemap.h>
> > #include <linux/fsnotify.h>
> > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > index f9a506147c8a..e4adf5e05afd 100644
> > --- a/include/linux/bpf.h
> > +++ b/include/linux/bpf.h
> > @@ -1050,6 +1050,7 @@ extern const struct bpf_func_proto bpf_get_local_storage_proto;
> > extern const struct bpf_func_proto bpf_strtol_proto;
> > extern const struct bpf_func_proto bpf_strtoul_proto;
> > extern const struct bpf_func_proto bpf_tcp_sock_proto;
> > +extern const struct bpf_func_proto bpf_get_current_pidns_info_proto;
> >
> > /* Shared helpers among cBPF and eBPF. */
> > void bpf_user_rnd_init_once(void);
> > diff --git a/include/linux/namei.h b/include/linux/namei.h
> > index 9138b4471dbf..b45c8b6f7cb4 100644
> > --- a/include/linux/namei.h
> > +++ b/include/linux/namei.h
> > @@ -6,6 +6,7 @@
> > #include <linux/path.h>
> > #include <linux/fcntl.h>
> > #include <linux/errno.h>
> > +#include <linux/fs.h>
> >
> > enum { MAX_NESTED_LINKS = 8 };
> >
> > @@ -97,6 +98,9 @@ extern void unlock_rename(struct dentry *, struct dentry *);
> >
> > extern void nd_jump_link(struct path *path);
> >
> > +extern int filename_lookup(int dfd, struct filename *name, unsigned flags,
> > + struct path *path, struct path *root);
> > +
> > static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
> > {
> > ((char *) name)[min(len, maxlen)] = '\0';
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index 4393bd4b2419..b0d4869fb860 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -2741,6 +2741,24 @@ union bpf_attr {
> > * **-EOPNOTSUPP** kernel configuration does not enable SYN cookies
> > *
> > * **-EPROTONOSUPPORT** IP packet version is not 4 or 6
> > + *
> > + * int bpf_get_current_pidns_info(struct bpf_pidns_info *pidns, u32 size_of_pidns)
> > + * Description
> > + * Copies into *pidns* pid, namespace id and tgid as seen by the
> > + * current namespace and also device from /proc/self/ns/pid.
> > + * *size_of_pidns* must be the size of *pidns*
> > + *
> > + * This helper is used when pid filtering is needed inside a
> > + * container as bpf_get_current_tgid() helper returns always the
> > + * pid id as seen by the root namespace.
> > + * Return
> > + * 0 on success
> > + *
> > + * **-EINVAL** if *size_of_pidns* is not valid or unable to get ns, pid
> > + * or tgid of the current task.
> > + *
> > + * **-ENOMEM** if allocation fails.
> > + *
> > */
> > #define __BPF_FUNC_MAPPER(FN) \
> > FN(unspec), \
> > @@ -2853,7 +2871,8 @@ union bpf_attr {
> > FN(sk_storage_get), \
> > FN(sk_storage_delete), \
> > FN(send_signal), \
> > - FN(tcp_gen_syncookie),
> > + FN(tcp_gen_syncookie), \
> > + FN(get_current_pidns_info),
> >
> > /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> > * function eBPF program intends to call
> > @@ -3604,4 +3623,10 @@ struct bpf_sockopt {
> > __s32 retval;
> > };
> >
> > +struct bpf_pidns_info {
> > + __u32 dev;
> > + __u32 nsid;
> > + __u32 tgid;
> > + __u32 pid;
> > +};
> > #endif /* _UAPI__LINUX_BPF_H__ */
> > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> > index 8191a7db2777..3159f2a0188c 100644
> > --- a/kernel/bpf/core.c
> > +++ b/kernel/bpf/core.c
> > @@ -2038,6 +2038,7 @@ const struct bpf_func_proto bpf_get_current_uid_gid_proto __weak;
> > const struct bpf_func_proto bpf_get_current_comm_proto __weak;
> > const struct bpf_func_proto bpf_get_current_cgroup_id_proto __weak;
> > const struct bpf_func_proto bpf_get_local_storage_proto __weak;
> > +const struct bpf_func_proto bpf_get_current_pidns_info __weak;
> >
> > const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)
> > {
> > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> > index 5e28718928ca..41fbf1f28a48 100644
> > --- a/kernel/bpf/helpers.c
> > +++ b/kernel/bpf/helpers.c
> > @@ -11,6 +11,12 @@
> > #include <linux/uidgid.h>
> > #include <linux/filter.h>
> > #include <linux/ctype.h>
> > +#include <linux/pid_namespace.h>
> > +#include <linux/major.h>
> > +#include <linux/stat.h>
> > +#include <linux/namei.h>
> > +#include <linux/version.h>
> > +
> >
> > #include "../../lib/kstrtox.h"
> >
> > @@ -312,6 +318,64 @@ void copy_map_value_locked(struct bpf_map *map, void *dst, void *src,
> > preempt_enable();
> > }
> >
> > +BPF_CALL_2(bpf_get_current_pidns_info, struct bpf_pidns_info *, pidns_info, u32,
> > + size)
> > +{
> > + const char *pidns_path = "/proc/self/ns/pid";
> > + struct pid_namespace *pidns = NULL;
> > + struct filename *tmp = NULL;
> > + struct inode *inode;
> > + struct path kp;
> > + pid_t tgid = 0;
> > + pid_t pid = 0;
> > + int ret;
> > + int len;
> > +
> > + if (unlikely(size != sizeof(struct bpf_pidns_info)))
> > + return -EINVAL;
> > + pidns = task_active_pid_ns(current);
> > + if (unlikely(!pidns))
> > + goto clear;
> > + pidns_info->nsid = pidns->ns.inum;
> > + pid = task_pid_nr_ns(current, pidns);
> > + if (unlikely(!pid))
> > + goto clear;
> > + tgid = task_tgid_nr_ns(current, pidns);
> > + if (unlikely(!tgid))
> > + goto clear;
> > + pidns_info->tgid = (u32) tgid;
> > + pidns_info->pid = (u32) pid;
> > + tmp = kmem_cache_alloc(names_cachep, GFP_ATOMIC);
> > + if (unlikely(!tmp)) {
> > + memset((void *)pidns_info, 0, (size_t) size);
> > + return -ENOMEM;
> > + }
> > + len = strlen(pidns_path) + 1;
> > + memcpy((char *)tmp->name, pidns_path, len);
> > + tmp->uptr = NULL;
> > + tmp->aname = NULL;
> > + tmp->refcnt = 1;
> > + ret = filename_lookup(AT_FDCWD, tmp, 0, &kp, NULL);
> > + if (ret) {
> > + memset((void *)pidns_info, 0, (size_t) size);
> > + return ret;
> > + }
> > + inode = d_backing_inode(kp.dentry);
> > + pidns_info->dev = inode->i_sb->s_dev;
> > + return 0;
> > +clear:
> > + memset((void *)pidns_info, 0, (size_t) size);
> > + return -EINVAL;
> > +}
> > +
> > +const struct bpf_func_proto bpf_get_current_pidns_info_proto = {
> > + .func = bpf_get_current_pidns_info,
> > + .gpl_only = false,
> > + .ret_type = RET_INTEGER,
> > + .arg1_type = ARG_PTR_TO_UNINIT_MEM,
> > + .arg2_type = ARG_CONST_SIZE,
> > +};
> > +
> > #ifdef CONFIG_CGROUPS
> > BPF_CALL_0(bpf_get_current_cgroup_id)
> > {
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index ca1255d14576..5e1dc22765a5 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -709,6 +709,8 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> > #endif
> > case BPF_FUNC_send_signal:
> > return &bpf_send_signal_proto;
> > + case BPF_FUNC_get_current_pidns_info:
> > + return &bpf_get_current_pidns_info_proto;
> > default:
> > return NULL;
> > }
> > diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> > index 1d9be26b4edd..238453ff27d2 100644
> > --- a/samples/bpf/Makefile
> > +++ b/samples/bpf/Makefile
> > @@ -53,6 +53,7 @@ hostprogs-y += task_fd_query
> > hostprogs-y += xdp_sample_pkts
> > hostprogs-y += ibumad
> > hostprogs-y += hbm
> > +hostprogs-y += trace_ns_info
> >
> > # Libbpf dependencies
> > LIBBPF = $(TOOLS_PATH)/lib/bpf/libbpf.a
> > @@ -109,6 +110,7 @@ task_fd_query-objs := bpf_load.o task_fd_query_user.o $(TRACE_HELPERS)
> > xdp_sample_pkts-objs := xdp_sample_pkts_user.o $(TRACE_HELPERS)
> > ibumad-objs := bpf_load.o ibumad_user.o $(TRACE_HELPERS)
> > hbm-objs := bpf_load.o hbm.o $(CGROUP_HELPERS)
> > +trace_ns_info-objs := bpf_load.o trace_ns_info_user.o
> >
> > # Tell kbuild to always build the programs
> > always := $(hostprogs-y)
> > @@ -170,6 +172,7 @@ always += xdp_sample_pkts_kern.o
> > always += ibumad_kern.o
> > always += hbm_out_kern.o
> > always += hbm_edt_kern.o
> > +always += trace_ns_info_user_kern.o
> >
> > KBUILD_HOSTCFLAGS += -I$(objtree)/usr/include
> > KBUILD_HOSTCFLAGS += -I$(srctree)/tools/lib/bpf/
> > diff --git a/samples/bpf/trace_ns_info_user.c b/samples/bpf/trace_ns_info_user.c
> > new file mode 100644
> > index 000000000000..e06d08db6f30
> > --- /dev/null
> > +++ b/samples/bpf/trace_ns_info_user.c
> > @@ -0,0 +1,35 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2018 Carlos Neira cneirabustos@...il.com
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of version 2 of the GNU General Public
> > + * License as published by the Free Software Foundation.
> > + */
> > +
> > +#include <stdio.h>
> > +#include <linux/bpf.h>
> > +#include <unistd.h>
> > +#include "bpf/libbpf.h"
> > +#include "bpf_load.h"
> > +
> > +/* This code was taken verbatim from tracex1_user.c, it's used
> > + * to exercize bpf_get_current_pidns_info() helper call.
> > + */
> > +int main(int ac, char **argv)
> > +{
> > + FILE *f;
> > + char filename[256];
> > +
> > + snprintf(filename, sizeof(filename), "%s_user_kern.o", argv[0]);
> > + printf("loading %s\n", filename);
> > +
> > + if (load_bpf_file(filename)) {
> > + printf("%s", bpf_log_buf);
> > + return 1;
> > + }
> > +
> > + f = popen("taskset 1 ping localhost", "r");
> > + (void) f;
> > + read_trace_pipe();
> > + return 0;
> > +}
> > diff --git a/samples/bpf/trace_ns_info_user_kern.c b/samples/bpf/trace_ns_info_user_kern.c
> > new file mode 100644
> > index 000000000000..96675e02b707
> > --- /dev/null
> > +++ b/samples/bpf/trace_ns_info_user_kern.c
> > @@ -0,0 +1,44 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2018 Carlos Neira cneirabustos@...il.com
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of version 2 of the GNU General Public
> > + * License as published by the Free Software Foundation.
> > + */
> > +#include <linux/skbuff.h>
> > +#include <linux/netdevice.h>
> > +#include <linux/version.h>
> > +#include <uapi/linux/bpf.h>
> > +#include "bpf_helpers.h"
> > +
> > +typedef __u64 u64;
> > +typedef __u32 u32;
> > +
> > +
> > +/* kprobe is NOT a stable ABI
> > + * kernel functions can be removed, renamed or completely change semantics.
> > + * Number of arguments and their positions can change, etc.
> > + * In such case this bpf+kprobe example will no longer be meaningful
> > + */
> > +
> > +/* This will call bpf_get_current_pidns_info() to display pid and ns values
> > + * as seen by the current namespace, on the far left you will see the pid as
> > + * seen as by the root namespace.
> > + */
> > +
> > +SEC("kprobe/__netif_receive_skb_core")
> > +int bpf_prog1(struct pt_regs *ctx)
> > +{
> > + char fmt[] = "nsid:%u, dev: %u, pid:%u\n";
> > + struct bpf_pidns_info nsinfo;
> > + int ok = 0;
> > +
> > + ok = bpf_get_current_pidns_info(&nsinfo, sizeof(nsinfo));
> > + if (ok == 0)
> > + bpf_trace_printk(fmt, sizeof(fmt), (u32)nsinfo.nsid,
> > + (u32) nsinfo.dev, (u32)nsinfo.pid);
> > +
> > + return 0;
> > +}
> > +char _license[] SEC("license") = "GPL";
> > +u32 _version SEC("version") = LINUX_VERSION_CODE;
> > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > index 4393bd4b2419..b0d4869fb860 100644
> > --- a/tools/include/uapi/linux/bpf.h
> > +++ b/tools/include/uapi/linux/bpf.h
> > @@ -2741,6 +2741,24 @@ union bpf_attr {
> > * **-EOPNOTSUPP** kernel configuration does not enable SYN cookies
> > *
> > * **-EPROTONOSUPPORT** IP packet version is not 4 or 6
> > + *
> > + * int bpf_get_current_pidns_info(struct bpf_pidns_info *pidns, u32 size_of_pidns)
> > + * Description
> > + * Copies into *pidns* pid, namespace id and tgid as seen by the
> > + * current namespace and also device from /proc/self/ns/pid.
> > + * *size_of_pidns* must be the size of *pidns*
> > + *
> > + * This helper is used when pid filtering is needed inside a
> > + * container as bpf_get_current_tgid() helper returns always the
> > + * pid id as seen by the root namespace.
> > + * Return
> > + * 0 on success
> > + *
> > + * **-EINVAL** if *size_of_pidns* is not valid or unable to get ns, pid
> > + * or tgid of the current task.
> > + *
> > + * **-ENOMEM** if allocation fails.
> > + *
> > */
> > #define __BPF_FUNC_MAPPER(FN) \
> > FN(unspec), \
> > @@ -2853,7 +2871,8 @@ union bpf_attr {
> > FN(sk_storage_get), \
> > FN(sk_storage_delete), \
> > FN(send_signal), \
> > - FN(tcp_gen_syncookie),
> > + FN(tcp_gen_syncookie), \
> > + FN(get_current_pidns_info),
> >
> > /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> > * function eBPF program intends to call
> > @@ -3604,4 +3623,10 @@ struct bpf_sockopt {
> > __s32 retval;
> > };
> >
> > +struct bpf_pidns_info {
> > + __u32 dev;
> > + __u32 nsid;
> > + __u32 tgid;
> > + __u32 pid;
> > +};
> > #endif /* _UAPI__LINUX_BPF_H__ */
> > diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> > index 3bd0f4a0336a..1f97b571b581 100644
> > --- a/tools/testing/selftests/bpf/Makefile
> > +++ b/tools/testing/selftests/bpf/Makefile
> > @@ -29,7 +29,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
> > test_cgroup_storage test_select_reuseport test_section_names \
> > test_netcnt test_tcpnotify_user test_sock_fields test_sysctl test_hashmap \
> > test_btf_dump test_cgroup_attach xdping test_sockopt test_sockopt_sk \
> > - test_sockopt_multi test_tcp_rtt
> > + test_sockopt_multi test_tcp_rtt test_pidns
> >
> > BPF_OBJ_FILES = $(patsubst %.c,%.o, $(notdir $(wildcard progs/*.c)))
> > TEST_GEN_FILES = $(BPF_OBJ_FILES)
> > diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
> > index 120aa86c58d3..c96795a9d983 100644
> > --- a/tools/testing/selftests/bpf/bpf_helpers.h
> > +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> > @@ -231,6 +231,9 @@ static int (*bpf_send_signal)(unsigned sig) = (void *)BPF_FUNC_send_signal;
> > static long long (*bpf_tcp_gen_syncookie)(struct bpf_sock *sk, void *ip,
> > int ip_len, void *tcp, int tcp_len) =
> > (void *) BPF_FUNC_tcp_gen_syncookie;
> > +static int (*bpf_get_current_pidns_info)(struct bpf_pidns_info *buf,
> > + unsigned int buf_size) =
> > + (void *) BPF_FUNC_get_current_pidns_info;
> >
> > /* llvm builtin functions that eBPF C program may use to
> > * emit BPF_LD_ABS and BPF_LD_IND instructions
> > diff --git a/tools/testing/selftests/bpf/progs/test_pidns_kern.c b/tools/testing/selftests/bpf/progs/test_pidns_kern.c
> > new file mode 100644
> > index 000000000000..e1d2facfa762
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/test_pidns_kern.c
> > @@ -0,0 +1,51 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2018 Carlos Neira cneirabustos@...il.com
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of version 2 of the GNU General Public
> > + * License as published by the Free Software Foundation.
> > + */
> > +
> > +#include <linux/bpf.h>
> > +#include <errno.h>
> > +#include "bpf_helpers.h"
> > +
> > +struct bpf_map_def SEC("maps") nsidmap = {
> > + .type = BPF_MAP_TYPE_ARRAY,
> > + .key_size = sizeof(__u32),
> > + .value_size = sizeof(__u32),
> > + .max_entries = 1,
> > +};
> > +
> > +struct bpf_map_def SEC("maps") pidmap = {
> > + .type = BPF_MAP_TYPE_ARRAY,
> > + .key_size = sizeof(__u32),
> > + .value_size = sizeof(__u32),
> > + .max_entries = 1,
> > +};
> > +
> > +SEC("tracepoint/syscalls/sys_enter_nanosleep")
> > +int trace(void *ctx)
> > +{
> > + struct bpf_pidns_info nsinfo;
> > + __u32 key = 0, *expected_pid, *val;
> > + char fmt[] = "ERROR nspid:%d\n";
> > +
> > + if (bpf_get_current_pidns_info(&nsinfo, sizeof(nsinfo)))
> > + return -EINVAL;
> > +
> > + expected_pid = bpf_map_lookup_elem(&pidmap, &key);
> > +
> > +
> > + if (!expected_pid || *expected_pid != nsinfo.pid)
> > + return 0;
> > +
> > + val = bpf_map_lookup_elem(&nsidmap, &key);
> > + if (val)
> > + *val = nsinfo.nsid;
> > +
> > + return 0;
> > +}
> > +
> > +char _license[] SEC("license") = "GPL";
> > +__u32 _version SEC("version") = 1;
> > diff --git a/tools/testing/selftests/bpf/test_pidns.c b/tools/testing/selftests/bpf/test_pidns.c
> > new file mode 100644
> > index 000000000000..a7254055f294
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/test_pidns.c
> > @@ -0,0 +1,138 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2018 Carlos Neira cneirabustos@...il.com
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of version 2 of the GNU General Public
> > + * License as published by the Free Software Foundation.
> > + */
> > +
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <string.h>
> > +#include <errno.h>
> > +#include <fcntl.h>
> > +#include <syscall.h>
> > +#include <unistd.h>
> > +#include <linux/perf_event.h>
> > +#include <sys/ioctl.h>
> > +#include <sys/time.h>
> > +#include <sys/types.h>
> > +#include <sys/stat.h>
> > +
> > +#include <linux/bpf.h>
> > +#include <bpf/bpf.h>
> > +#include <bpf/libbpf.h>
> > +
> > +#include "cgroup_helpers.h"
> > +#include "bpf_rlimit.h"
> > +
> > +#define CHECK(condition, tag, format...) ({ \
> > + int __ret = !!(condition); \
> > + if (__ret) { \
> > + printf("%s:FAIL:%s ", __func__, tag); \
> > + printf(format); \
> > + } else { \
> > + printf("%s:PASS:%s\n", __func__, tag); \
> > + } \
> > + __ret; \
> > +})
> > +
> > +static int bpf_find_map(const char *test, struct bpf_object *obj,
> > + const char *name)
> > +{
> > + struct bpf_map *map;
> > +
> > + map = bpf_object__find_map_by_name(obj, name);
> > + if (!map)
> > + return -1;
> > + return bpf_map__fd(map);
> > +}
> > +
> > +
> > +int main(int argc, char **argv)
> > +{
> > + const char *probe_name = "syscalls/sys_enter_nanosleep";
> > + const char *file = "test_pidns_kern.o";
> > + int err, bytes, efd, prog_fd, pmu_fd;
> > + int pidmap_fd, nsidmap_fd;
> > + struct perf_event_attr attr = {};
> > + struct bpf_object *obj;
> > + __u32 knsid = 0;
> > + __u32 key = 0, pid;
> > + int exit_code = 1;
> > + struct stat st;
> > + char buf[256];
> > +
> > + err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
> > + if (CHECK(err, "bpf_prog_load", "err %d errno %d\n", err, errno))
> > + goto cleanup_cgroup_env;
> > +
> > + nsidmap_fd = bpf_find_map(__func__, obj, "nsidmap");
> > + if (CHECK(nsidmap_fd < 0, "bpf_find_map", "err %d errno %d\n",
> > + nsidmap_fd, errno))
> > + goto close_prog;
> > +
> > + pidmap_fd = bpf_find_map(__func__, obj, "pidmap");
> > + if (CHECK(pidmap_fd < 0, "bpf_find_map", "err %d errno %d\n",
> > + pidmap_fd, errno))
> > + goto close_prog;
> > +
> > + pid = getpid();
> > + bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
> > +
> > + snprintf(buf, sizeof(buf),
> > + "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > + efd = open(buf, O_RDONLY, 0);
> > + if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
> > + goto close_prog;
> > + bytes = read(efd, buf, sizeof(buf));
> > + close(efd);
> > + if (CHECK(bytes <= 0 || bytes >= sizeof(buf), "read",
> > + "bytes %d errno %d\n", bytes, errno))
> > + goto close_prog;
> > +
> > + attr.config = strtol(buf, NULL, 0);
> > + attr.type = PERF_TYPE_TRACEPOINT;
> > + attr.sample_type = PERF_SAMPLE_RAW;
> > + attr.sample_period = 1;
> > + attr.wakeup_events = 1;
> > +
> > + pmu_fd = syscall(__NR_perf_event_open, &attr, getpid(), -1, -1, 0);
> > + if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n", pmu_fd,
> > + errno))
> > + goto close_prog;
> > +
> > + err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
> > + if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n", err,
> > + errno))
> > + goto close_pmu;
> > +
> > + err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
> > + if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n", err,
> > + errno))
> > + goto close_pmu;
> > +
> > + /* trigger some syscalls */
> > + sleep(1);
> > +
> > + err = bpf_map_lookup_elem(nsidmap_fd, &key, &knsid);
> > + if (CHECK(err, "bpf_map_lookup_elem", "err %d errno %d\n", err, errno))
> > + goto close_pmu;
> > +
> > + if (stat("/proc/self/ns/pid", &st))
> > + goto close_pmu;
> > +
> > + if (CHECK(knsid != (__u32) st.st_ino, "compare_namespace_id",
> > + "kern knsid %u user unsid %u\n", knsid, (__u32) st.st_ino))
> > + goto close_pmu;
> > +
> > + exit_code = 0;
> > + printf("%s:PASS\n", argv[0]);
> > +
> > +close_pmu:
> > + close(pmu_fd);
> > +close_prog:
> > + bpf_object__close(obj);
> > +cleanup_cgroup_env:
> > + return exit_code;
> > +}
> > --
> > 2.11.0
> >
> >
> >
> >
> >
> >
> > On Thu, Aug 08, 2019 at 05:09:51AM +0000, Yonghong Song wrote:
> > >
> > >
> > > On 8/7/19 6:22 PM, Carlos Antonio Neira Bustos wrote:
> > > > The code has been modified to avoid syscalls that could sleep.
> > > > Please let me know if any other modification is needed.
> > > >
> > > > From be0384c0fa209a78c1567936e8db4e35b9a7c0f8 Mon Sep 17 00:00:00 2001
> > > > From: Carlos <cneirabustos@...il.com>
> > > > Date: Wed, 7 Aug 2019 20:04:30 -0400
> > > > Subject: [PATCH] [PATCH v5 bpf-next] BPF: New helper to obtain namespace data
> > > > from current task
> > > >
> > > > This helper obtains the active namespace from current and returns pid, tgid,
> > > > device and namespace id as seen from that namespace, allowing to instrument
> > > > a process inside a container.
> > > > Device is read from /proc/self/ns/pid, as in the future it's possible that
> > > > different pid_ns files may belong to different devices, according
> > > > to the discussion between Eric Biederman and Yonghong in 2017 linux plumbers
> > > > conference.
> > > > Currently bpf_get_current_pid_tgid(), is used to do pid filtering in bcc's
> > > > scripts but this helper returns the pid as seen by the root namespace which is
> > > > fine when a bcc script is not executed inside a container.
> > > > When the process of interest is inside a container, pid filtering will not work
> > > > if bpf_get_current_pid_tgid() is used. This helper addresses this limitation
> > > > returning the pid as it's seen by the current namespace where the script is
> > > > executing.
> > > >
> > > > This helper has the same use cases as bpf_get_current_pid_tgid() as it can be
> > > > used to do pid filtering even inside a container.
> > > >
> > > > For example a bcc script using bpf_get_current_pid_tgid() (tools/funccount.py):
> > > >
> > > > u32 pid = bpf_get_current_pid_tgid() >> 32;
> > > > if (pid != <pid_arg_passed_in>)
> > > > return 0;
> > > > Could be modified to use bpf_get_current_pidns_info() as follows:
> > > >
> > > > struct bpf_pidns pidns;
> > > > bpf_get_current_pidns_info(&pidns, sizeof(struct bpf_pidns));
> > > > u32 pid = pidns.tgid;
> > > > u32 nsid = pidns.nsid;
> > > > if ((pid != <pid_arg_passed_in>) && (nsid != <nsid_arg_passed_in>))
> > > > return 0;
> > > >
> > > > To find out the name PID namespace id of a process, you could use this command:
> > > >
> > > > $ ps -h -o pidns -p <pid_of_interest>
> > > >
> > > > Or this other command:
> > > >
> > > > $ ls -Li /proc/<pid_of_interest>/ns/pid
> > > >
> > > > Signed-off-by: Carlos Neira <cneirabustos@...il.com>
> > > > ---
> > > > fs/namei.c | 2 +-
> > > > include/linux/bpf.h | 1 +
> > > > include/linux/namei.h | 4 +
> > > > include/uapi/linux/bpf.h | 29 ++++-
> > > > kernel/bpf/core.c | 1 +
> > > > kernel/bpf/helpers.c | 78 ++++++++++++
> > > > kernel/trace/bpf_trace.c | 2 +
> > > > samples/bpf/Makefile | 3 +
> > > > samples/bpf/trace_ns_info_user.c | 35 ++++++
> > > > samples/bpf/trace_ns_info_user_kern.c | 44 +++++++
> > > > tools/include/uapi/linux/bpf.h | 29 ++++-
> > > > tools/testing/selftests/bpf/Makefile | 2 +-
> > > > tools/testing/selftests/bpf/bpf_helpers.h | 3 +
> > > > .../testing/selftests/bpf/progs/test_pidns_kern.c | 51 ++++++++
> > > > tools/testing/selftests/bpf/test_pidns.c | 138 +++++++++++++++++++++
> > > > 15 files changed, 418 insertions(+), 4 deletions(-)
> > > > create mode 100644 samples/bpf/trace_ns_info_user.c
> > > > create mode 100644 samples/bpf/trace_ns_info_user_kern.c
> > > > create mode 100644 tools/testing/selftests/bpf/progs/test_pidns_kern.c
> > > > create mode 100644 tools/testing/selftests/bpf/test_pidns.c
> > > >
> > > > diff --git a/fs/namei.c b/fs/namei.c
> > > > index 209c51a5226c..d1eca36972d2 100644
> > > > --- a/fs/namei.c
> > > > +++ b/fs/namei.c
> > > > @@ -19,7 +19,6 @@
> > > > #include <linux/export.h>
> > > > #include <linux/kernel.h>
> > > > #include <linux/slab.h>
> > > > -#include <linux/fs.h>
> > > > #include <linux/namei.h>
> > > > #include <linux/pagemap.h>
> > > > #include <linux/fsnotify.h>
> > > > @@ -2355,6 +2354,7 @@ int filename_lookup(int dfd, struct filename *name, unsigned flags,
> > > > putname(name);
> > > > return retval;
> > > > }
> > > > +EXPORT_SYMBOL(filename_lookup);
> > >
> > > No need to export symbols. bpf uses it and bpf is in the core, not in
> > > modules.
> > >
> > > >
> > > > /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
> > > > static int path_parentat(struct nameidata *nd, unsigned flags,
> > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > > > index f9a506147c8a..e4adf5e05afd 100644
> > > > --- a/include/linux/bpf.h
> > > > +++ b/include/linux/bpf.h
> > > > @@ -1050,6 +1050,7 @@ extern const struct bpf_func_proto bpf_get_local_storage_proto;
> > > > extern const struct bpf_func_proto bpf_strtol_proto;
> > > > extern const struct bpf_func_proto bpf_strtoul_proto;
> > > > extern const struct bpf_func_proto bpf_tcp_sock_proto;
> > > > +extern const struct bpf_func_proto bpf_get_current_pidns_info_proto;
> > > >
> > > > /* Shared helpers among cBPF and eBPF. */
> > > > void bpf_user_rnd_init_once(void);
> > > > diff --git a/include/linux/namei.h b/include/linux/namei.h
> > > > index 9138b4471dbf..2c24e8c71d46 100644
> > > > --- a/include/linux/namei.h
> > > > +++ b/include/linux/namei.h
> > > > @@ -6,6 +6,7 @@
> > > > #include <linux/path.h>
> > > > #include <linux/fcntl.h>
> > > > #include <linux/errno.h>
> > > > +#include <linux/fs.h>
> > > >
> > > > enum { MAX_NESTED_LINKS = 8 };
> > > >
> > > > @@ -97,6 +98,9 @@ extern void unlock_rename(struct dentry *, struct dentry *);
> > > >
> > > > extern void nd_jump_link(struct path *path);
> > > >
> > > > +extern int filename_lookup(int dfd, struct filename *name, unsigned int flags,
> > > > + struct path *path, struct path *root);
> > >
> > > The previous definition in fs/internal.h should be removed.
> > >
> > > > +
> > > > static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
> > > > {
> > > > ((char *) name)[min(len, maxlen)] = '\0';
> > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > > > index 4393bd4b2419..6f601f7106e2 100644
> > > > --- a/include/uapi/linux/bpf.h
> > > > +++ b/include/uapi/linux/bpf.h
> > > > @@ -2741,6 +2741,26 @@ union bpf_attr {
> > > > * **-EOPNOTSUPP** kernel configuration does not enable SYN cookies
> > > > *
> > > > * **-EPROTONOSUPPORT** IP packet version is not 4 or 6
> > > > + *
> > > > + * int bpf_get_current_pidns_info(struct bpf_pidns_info *pidns, u32 size_of_pidns)
> > > > + * Description
> > > > + * Copies into *pidns* pid, namespace id and tgid as seen by the
> > > > + * current namespace and also device from /proc/self/ns/pid.
> > > > + * *size_of_pidns* must be the size of *pidns*
> > > > + *
> > > > + * This helper is used when pid filtering is needed inside a
> > > > + * container as bpf_get_current_tgid() helper returns always the
> > > > + * pid id as seen by the root namespace.
> > > > + * Return
> > > > + * 0 on success
> > > > + *
> > > > + * **-EINVAL** if unable to get ns, pid or tgid of current task.
> > > > + * Or if size_of_pidns is not valid.
> > >
> > > Maybe reword by following the code sequence.
> > > if *size_of_pidns* is not valid or unable to get ns, pid or tgid of
> > > the current task.
> > >
> > > > + *
> > > > + * **-ENOMEM** if allocation fails.
> > >
> > > Maybe some other error codes in filename_lookup() function?
> > >
> > > > + *
> > > > + * If unable to get the inode from /proc/self/ns/pid an error code
> > > > + * will be returned.
> > >
> > > You do not need this. The description of error code cases should cover this.
> > >
> > > > */
> > > > #define __BPF_FUNC_MAPPER(FN) \
> > > > FN(unspec), \
> > > > @@ -2853,7 +2873,8 @@ union bpf_attr {
> > > > FN(sk_storage_get), \
> > > > FN(sk_storage_delete), \
> > > > FN(send_signal), \
> > > > - FN(tcp_gen_syncookie),
> > > > + FN(tcp_gen_syncookie), \
> > > > + FN(get_current_pidns_info),
> > > >
> > > > /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> > > > * function eBPF program intends to call
> > > > @@ -3604,4 +3625,10 @@ struct bpf_sockopt {
> > > > __s32 retval;
> > > > };
> > > >
> > > > +struct bpf_pidns_info {
> > > > + __u32 dev;
> > > > + __u32 nsid;
> > > > + __u32 tgid;
> > > > + __u32 pid;
> > > > +};
> > > > #endif /* _UAPI__LINUX_BPF_H__ */
> > > > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> > > > index 8191a7db2777..3159f2a0188c 100644
> > > > --- a/kernel/bpf/core.c
> > > > +++ b/kernel/bpf/core.c
> > > > @@ -2038,6 +2038,7 @@ const struct bpf_func_proto bpf_get_current_uid_gid_proto __weak;
> > > > const struct bpf_func_proto bpf_get_current_comm_proto __weak;
> > > > const struct bpf_func_proto bpf_get_current_cgroup_id_proto __weak;
> > > > const struct bpf_func_proto bpf_get_local_storage_proto __weak;
> > > > +const struct bpf_func_proto bpf_get_current_pidns_info __weak;
> > > >
> > > > const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)
> > > > {
> > > > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> > > > index 5e28718928ca..571f24077db2 100644
> > > > --- a/kernel/bpf/helpers.c
> > > > +++ b/kernel/bpf/helpers.c
> > > > @@ -11,6 +11,12 @@
> > > > #include <linux/uidgid.h>
> > > > #include <linux/filter.h>
> > > > #include <linux/ctype.h>
> > > > +#include <linux/pid_namespace.h>
> > > > +#include <linux/major.h>
> > > > +#include <linux/stat.h>
> > > > +#include <linux/namei.h>
> > > > +#include <linux/version.h>
> > > > +
> > > >
> > > > #include "../../lib/kstrtox.h"
> > > >
> > > > @@ -312,6 +318,78 @@ void copy_map_value_locked(struct bpf_map *map, void *dst, void *src,
> > > > preempt_enable();
> > > > }
> > > >
> > > > +BPF_CALL_2(bpf_get_current_pidns_info, struct bpf_pidns_info *, pidns_info, u32,
> > > > + size)
> > > > +{
> > > > + const char *name = "/proc/self/ns/pid";
> > >
> > > maybe rename this variable to pidns_path?
> > >
> > > > + struct pid_namespace *pidns = NULL;
> > > > + struct filename *tmp = NULL;
> > >
> > > Maybe rename this variable to name?
> > >
> > > > + int len = strlen(name) + 1;
> > >
> > > We can delay this assignment later until it is needed.
> > >
> > > > + struct inode *inode;
> > > > + struct path kp;
> > > > + pid_t tgid = 0;
> > > > + pid_t pid = 0;
> > > > + int ret;
> > > > +
> > > > + if (unlikely(size != sizeof(struct bpf_pidns_info)))
> > > > + return -EINVAL;
> > > > +
> > > > + pidns = task_active_pid_ns(current);
> > > > +
> > >
> > > we can save an empty line here.
> > >
> > > > + if (unlikely(!pidns))
> > > > + goto clear;
> > > > +
> > > > + pidns_info->nsid = pidns->ns.inum;
> > > > + pid = task_pid_nr_ns(current, pidns);
> > > > +
> > >
> > > We can save an empty line here.
> > >
> > > > + if (unlikely(!pid))
> > > > + goto clear;
> > > > +
> > > > + tgid = task_tgid_nr_ns(current, pidns);
> > > > +
> > > ditto. save an empty line.
> > > > + if (unlikely(!tgid))
> > > > + goto clear;
> > > > +
> > > > + pidns_info->tgid = (u32) tgid;
> > > > + pidns_info->pid = (u32) pid;
> > > > +
> > > > + tmp = kmem_cache_alloc(names_cachep, GFP_ATOMIC);
> > > > + if (unlikely(!tmp)) {
> > > > + memset((void *)pidns_info, 0, (size_t) size);
> > > > + return -ENOMEM;
> > > > + }
> > > > +
> > > > + memcpy((char *)tmp->name, name, len);
> > > > + tmp->uptr = NULL;
> > > > + tmp->aname = NULL;
> > > > + tmp->refcnt = 1;
> > > > +
> > > ditto. save an empty line.
> > > > + ret = filename_lookup(AT_FDCWD, tmp, 0, &kp, NULL);
> > > > +
> > > ditto. save an empty line.
> > > > + if (ret) {
> > > > + memset((void *)pidns_info, 0, (size_t) size);
> > > > + return ret;
> > > > + }
> > > > +
> > > > + inode = d_backing_inode(kp.dentry);
> > > > + pidns_info->dev = inode->i_sb->s_dev;
> > > > +
> > > > + return 0;
> > > > +
> > > > +clear:
> > > > + memset((void *)pidns_info, 0, (size_t) size);
> > > > +
> > > save an empty line.
> > > > + return -EINVAL;
> > > > +}
> > > > +
> > > > +const struct bpf_func_proto bpf_get_current_pidns_info_proto = {
> > > > + .func = bpf_get_current_pidns_info,
> > > make the "= " aligned with others?
> > > > + .gpl_only = false,
> > > > + .ret_type = RET_INTEGER,
> > > > + .arg1_type = ARG_PTR_TO_UNINIT_MEM,
> > > > + .arg2_type = ARG_CONST_SIZE,
> > > > +};
> > > > +
> > > > #ifdef CONFIG_CGROUPS
> > > > BPF_CALL_0(bpf_get_current_cgroup_id)
> > > > {
> > > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > > > index ca1255d14576..5e1dc22765a5 100644
> > > > --- a/kernel/trace/bpf_trace.c
> > > > +++ b/kernel/trace/bpf_trace.c
> > > > @@ -709,6 +709,8 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> > > > #endif
> > > > case BPF_FUNC_send_signal:
> > > > return &bpf_send_signal_proto;
> > > > + case BPF_FUNC_get_current_pidns_info:
> > > > + return &bpf_get_current_pidns_info_proto;
> > > > default:
> > > > return NULL;
> > > > }
> > > > diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> > > > index 1d9be26b4edd..238453ff27d2 100644
> > > > --- a/samples/bpf/Makefile
> > > > +++ b/samples/bpf/Makefile
> > > > @@ -53,6 +53,7 @@ hostprogs-y += task_fd_query
> > > > hostprogs-y += xdp_sample_pkts
> > > > hostprogs-y += ibumad
> > > > hostprogs-y += hbm
> > > > +hostprogs-y += trace_ns_info
> > > [...]
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