From 95436dbf882f32ed98f73ec080021daf3841f4a9 Mon Sep 17 00:00:00 2001 From: Andrea Claudi Date: Fri, 28 Jun 2019 14:12:36 +0200 Subject: [PATCH] netns: switch netns in the child when executing commands Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1719759 Upstream Status: iproute2.git commit 903818fbf9c73 commit 903818fbf9c73dd71793e5829775d2ccc1775af5 Author: Matteo Croce Date: Tue Jun 18 16:49:33 2019 +0200 netns: switch netns in the child when executing commands 'ip netns exec' changes the current netns just before executing a child process, and restores it after forking. This is needed if we're running in batch or do_all mode. Some cleanups must be done both in the parent and in the child: the parent must restore the previous netns, while the child must reset any VRF association. Unfortunately, if do_all is set, the VRF are not reset in the child, and the spawned processes are started with the wrong VRF context. This can be triggered with this script: # ip -b - <<-'EOF' link add type vrf table 100 link set vrf0 up link add type dummy link set dummy0 vrf vrf0 up netns add ns1 EOF # ip -all -b - <<-'EOF' vrf exec vrf0 true netns exec setsid -f sleep 1h EOF # ip vrf pids vrf0 314 sleep # ps 314 PID TTY STAT TIME COMMAND 314 ? Ss 0:00 sleep 1h Refactor cmd_exec() and pass to it a function pointer which is called in the child before the final exec. In the netns exec case the function just resets the VRF and switches netns. Doing it in the child is less error prone and safer, because the parent environment is always kept unaltered. After this refactor some utility functions became unused, so remove them. Signed-off-by: Matteo Croce Signed-off-by: Stephen Hemminger --- include/utils.h | 6 ++---- ip/ipnetns.c | 30 ++++++++++++++++-------------- ip/ipvrf.c | 2 +- lib/exec.c | 7 ++++++- lib/utils.c | 27 --------------------------- 5 files changed, 25 insertions(+), 47 deletions(-) diff --git a/include/utils.h b/include/utils.h index c32b37a1797d8..f00e7742b3c2a 100644 --- a/include/utils.h +++ b/include/utils.h @@ -292,14 +292,12 @@ extern int cmdlineno; ssize_t getcmdline(char **line, size_t *len, FILE *in); int makeargs(char *line, char *argv[], int maxargs); -int do_each_netns(int (*func)(char *nsname, void *arg), void *arg, - bool show_label); - char *int_to_str(int val, char *buf); int get_guid(__u64 *guid, const char *arg); int get_real_family(int rtm_type, int rtm_family); -int cmd_exec(const char *cmd, char **argv, bool do_fork); +int cmd_exec(const char *cmd, char **argv, bool do_fork, + int (*setup)(void *), void *arg); int make_path(const char *path, mode_t mode); char *find_cgroup2_mount(void); int get_command_name(const char *pid, char *comm, size_t len); diff --git a/ip/ipnetns.c b/ip/ipnetns.c index a6e3ea575c363..10bfe2eb69e0b 100644 --- a/ip/ipnetns.c +++ b/ip/ipnetns.c @@ -395,11 +395,24 @@ static int netns_list(int argc, char **argv) return 0; } +static int do_switch(void *arg) +{ + char *netns = arg; + + /* we just changed namespaces. clear any vrf association + * with prior namespace before exec'ing command + */ + vrf_reset(); + + return netns_switch(netns); +} + static int on_netns_exec(char *nsname, void *arg) { char **argv = arg; - cmd_exec(argv[1], argv + 1, true); + printf("\nnetns: %s\n", nsname); + cmd_exec(argv[0], argv, true, do_switch, nsname); return 0; } @@ -408,8 +421,6 @@ static int netns_exec(int argc, char **argv) /* Setup the proper environment for apps that are not netns * aware, and execute a program in that environment. */ - const char *cmd; - if (argc < 1 && !do_all) { fprintf(stderr, "No netns name specified\n"); return -1; @@ -420,22 +431,13 @@ static int netns_exec(int argc, char **argv) } if (do_all) - return do_each_netns(on_netns_exec, --argv, 1); - - if (netns_switch(argv[0])) - return -1; - - /* we just changed namespaces. clear any vrf association - * with prior namespace before exec'ing command - */ - vrf_reset(); + return netns_foreach(on_netns_exec, argv); /* ip must return the status of the child, * but do_cmd() will add a minus to this, * so let's add another one here to cancel it. */ - cmd = argv[1]; - return -cmd_exec(cmd, argv + 1, !!batch_mode); + return -cmd_exec(argv[1], argv + 1, !!batch_mode, do_switch, argv[0]); } static int is_pid(const char *str) diff --git a/ip/ipvrf.c b/ip/ipvrf.c index 8a6b7f977b142..c93ff71b39070 100644 --- a/ip/ipvrf.c +++ b/ip/ipvrf.c @@ -455,7 +455,7 @@ static int ipvrf_exec(int argc, char **argv) if (vrf_switch(argv[0])) return -1; - return -cmd_exec(argv[1], argv + 1, !!batch_mode); + return -cmd_exec(argv[1], argv + 1, !!batch_mode, NULL, NULL); } /* reset VRF association of current process to default VRF; diff --git a/lib/exec.c b/lib/exec.c index eb36b59dee7f4..9b1c8f4a13960 100644 --- a/lib/exec.c +++ b/lib/exec.c @@ -5,8 +5,10 @@ #include #include "utils.h" +#include "namespace.h" -int cmd_exec(const char *cmd, char **argv, bool do_fork) +int cmd_exec(const char *cmd, char **argv, bool do_fork, + int (*setup)(void *), void *arg) { fflush(stdout); if (do_fork) { @@ -34,6 +36,9 @@ int cmd_exec(const char *cmd, char **argv, bool do_fork) } } + if (setup && setup(arg)) + return -1; + if (execvp(cmd, argv) < 0) fprintf(stderr, "exec of \"%s\" failed: %s\n", cmd, strerror(errno)); diff --git a/lib/utils.c b/lib/utils.c index 7be2d6bec5215..5f229a9a4f584 100644 --- a/lib/utils.c +++ b/lib/utils.c @@ -1455,33 +1455,6 @@ void print_nlmsg_timestamp(FILE *fp, const struct nlmsghdr *n) fprintf(fp, "Timestamp: %s %lu us\n", tstr, usecs); } -static int on_netns(char *nsname, void *arg) -{ - struct netns_func *f = arg; - - if (netns_switch(nsname)) - return -1; - - return f->func(nsname, f->arg); -} - -static int on_netns_label(char *nsname, void *arg) -{ - printf("\nnetns: %s\n", nsname); - return on_netns(nsname, arg); -} - -int do_each_netns(int (*func)(char *nsname, void *arg), void *arg, - bool show_label) -{ - struct netns_func nsf = { .func = func, .arg = arg }; - - if (show_label) - return netns_foreach(on_netns_label, &nsf); - - return netns_foreach(on_netns, &nsf); -} - char *int_to_str(int val, char *buf) { sprintf(buf, "%d", val); -- 2.20.1