busybox: fix: ip addr flush hangs when run by non-root user
authorMikael Magnusson <mikma@users.sourceforge.net>
Mon, 27 May 2019 20:48:10 +0000 (22:48 +0200)
committerHans Dedecker <dedeckeh@gmail.com>
Tue, 28 May 2019 11:18:58 +0000 (13:18 +0200)
Add upstream patch from:
https://git.busybox.net/busybox/commit/?id=028c5aa18b5273c029f0278232d922ee1a164de6

The patch fixes a problem with an infinite loop causing 100% CPU usage
when running the following command /lib/preinit/10_indicate_preinit
without the CAP_NET_ADMIN capability (such as in Docker):
  ip -4 address flush dev $pi_ifname

Signed-off-by: Mikael Magnusson <mikma@users.sourceforge.net>
Signed-off-by: Hans Dedecker <dedeckeh@gmail.com> [refresh patch]
package/utils/busybox/Makefile
package/utils/busybox/patches/530-ip-use-rtnl_send_check-on-flush-commands.patch [new file with mode: 0644]

index 8ccf435..ff25a35 100644 (file)
@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=busybox
 PKG_VERSION:=1.30.1
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 PKG_FLAGS:=essential
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2
diff --git a/package/utils/busybox/patches/530-ip-use-rtnl_send_check-on-flush-commands.patch b/package/utils/busybox/patches/530-ip-use-rtnl_send_check-on-flush-commands.patch
new file mode 100644 (file)
index 0000000..0e8ec37
--- /dev/null
@@ -0,0 +1,214 @@
+From 028c5aa18b5273c029f0278232d922ee1a164de6 Mon Sep 17 00:00:00 2001
+From: Denys Vlasenko <vda.linux@googlemail.com>
+Date: Wed, 22 May 2019 13:54:46 +0200
+Subject: ip: use rtnl_send_check() on flush commands, closes 6962
+
+function                                             old     new   delta
+rtnl_send_check                                        -     160    +160
+xrtnl_wilddump_request                                64      66      +2
+ipneigh_list_or_flush                                714     706      -8
+rtnl_send                                             69       -     -69
+------------------------------------------------------------------------------
+(add/remove: 1/1 grow/shrink: 1/1 up/down: 162/-77)            Total: 85 bytes
+
+Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
+---
+ networking/libiproute/ipaddress.c  |  6 ++++--
+ networking/libiproute/ipneigh.c    |  9 ++++----
+ networking/libiproute/iproute.c    |  5 ++++-
+ networking/libiproute/libnetlink.c | 43 +++++++++++++++++++++++++++++++-------
+ networking/libiproute/libnetlink.h | 19 +++++++++++++++--
+ 5 files changed, 65 insertions(+), 17 deletions(-)
+
+--- a/networking/libiproute/ipaddress.c
++++ b/networking/libiproute/ipaddress.c
+@@ -23,6 +23,7 @@
+ struct filter_t {
+       char *label;
++      /* Flush cmd buf. If !NULL, print_addrinfo() constructs flush commands in it */
+       char *flushb;
+       struct rtnl_handle *rth;
+       int scope, scopemask;
+@@ -34,6 +35,8 @@ struct filter_t {
+       smallint showqueue;
+       smallint oneline;
+       smallint up;
++      /* Misnomer. Does not mean "flushed something" */
++      /* More like "flush commands were constructed by print_addrinfo()" */
+       smallint flushed;
+       inet_prefix pfx;
+ } FIX_ALIASING;
+@@ -201,7 +204,7 @@ static NOINLINE int print_linkinfo(const
+ static int flush_update(void)
+ {
+-      if (rtnl_send(G_filter.rth, G_filter.flushb, G_filter.flushp) < 0) {
++      if (rtnl_send_check(G_filter.rth, G_filter.flushb, G_filter.flushp) < 0) {
+               bb_perror_msg("can't send flush request");
+               return -1;
+       }
+@@ -507,7 +510,6 @@ int FAST_FUNC ipaddr_list_or_flush(char
+               xrtnl_dump_filter(&rth, store_nlmsg, &ainfo);
+       }
+-
+       if (G_filter.family && G_filter.family != AF_PACKET) {
+               struct nlmsg_list **lp;
+               lp = &linfo;
+--- a/networking/libiproute/ipneigh.c
++++ b/networking/libiproute/ipneigh.c
+@@ -32,7 +32,10 @@ struct filter_t {
+       int state;
+       int unused_only;
+       inet_prefix pfx;
++      /* Misnomer. Does not mean "flushed N something" */
++      /* More like "no_of_flush_commands_constructed_by_print_neigh()" */
+       int flushed;
++      /* Flush cmd buf. If !NULL, print_neigh() constructs flush commands in it */
+       char *flushb;
+       int flushp;
+       int flushe;
+@@ -45,7 +48,7 @@ typedef struct filter_t filter_t;
+ static int flush_update(void)
+ {
+-      if (rtnl_send(G_filter.rth, G_filter.flushb, G_filter.flushp) < 0) {
++      if (rtnl_send_check(G_filter.rth, G_filter.flushb, G_filter.flushp) < 0) {
+               bb_perror_msg("can't send flush request");
+               return -1;
+       }
+@@ -299,9 +302,7 @@ static int FAST_FUNC ipneigh_list_or_flu
+               G_filter.rth = &rth;
+               while (round < MAX_ROUNDS) {
+-                      if (xrtnl_wilddump_request(&rth, G_filter.family, RTM_GETNEIGH) < 0) {
+-                              bb_perror_msg_and_die("can't send dump request");
+-                      }
++                      xrtnl_wilddump_request(&rth, G_filter.family, RTM_GETNEIGH);
+                       G_filter.flushed = 0;
+                       if (xrtnl_dump_filter(&rth, print_neigh, NULL) < 0) {
+                               bb_perror_msg_and_die("flush terminated");
+--- a/networking/libiproute/iproute.c
++++ b/networking/libiproute/iproute.c
+@@ -26,7 +26,10 @@
+ struct filter_t {
+       int tb;
++      /* Misnomer. Does not mean "flushed something" */
++      /* More like "flush commands were constructed by print_route()" */
+       smallint flushed;
++      /* Flush cmd buf. If !NULL, print_route() constructs flush commands in it */
+       char *flushb;
+       int flushp;
+       int flushe;
+@@ -53,7 +56,7 @@ typedef struct filter_t filter_t;
+ static int flush_update(void)
+ {
+-      if (rtnl_send(G_filter.rth, G_filter.flushb, G_filter.flushp) < 0) {
++      if (rtnl_send_check(G_filter.rth, G_filter.flushb, G_filter.flushp) < 0) {
+               bb_perror_msg("can't send flush request");
+               return -1;
+       }
+--- a/networking/libiproute/libnetlink.c
++++ b/networking/libiproute/libnetlink.c
+@@ -34,7 +34,7 @@ void FAST_FUNC xrtnl_open(struct rtnl_ha
+       rth->seq = time(NULL);
+ }
+-int FAST_FUNC xrtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)
++void FAST_FUNC xrtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)
+ {
+       struct {
+               struct nlmsghdr nlh;
+@@ -48,18 +48,45 @@ int FAST_FUNC xrtnl_wilddump_request(str
+       req.nlh.nlmsg_seq = rth->dump = ++rth->seq;
+       req.g.rtgen_family = family;
+-      return rtnl_send(rth, (void*)&req, sizeof(req));
++      rtnl_send(rth, (void*)&req, sizeof(req));
+ }
+-//TODO: pass rth->fd instead of full rth?
+-int FAST_FUNC rtnl_send(struct rtnl_handle *rth, char *buf, int len)
++/* A version which checks for e.g. EPERM errors.
++ * Try: setuidgid 1:1 ip addr flush dev eth0
++ */
++int FAST_FUNC rtnl_send_check(struct rtnl_handle *rth, const void *buf, int len)
+ {
+-      struct sockaddr_nl nladdr;
++      struct nlmsghdr *h;
++      int status;
++      char resp[1024];
++
++      status = write(rth->fd, buf, len);
++      if (status < 0)
++              return status;
++
++      /* Check for immediate errors */
++      status = recv(rth->fd, resp, sizeof(resp), MSG_DONTWAIT|MSG_PEEK);
++      if (status < 0) {
++              if (errno == EAGAIN) /* if no error, this happens */
++                      return 0;
++              return -1;
++      }
++
++      for (h = (struct nlmsghdr *)resp;
++          NLMSG_OK(h, status);
++          h = NLMSG_NEXT(h, status)
++      ) {
++              if (h->nlmsg_type == NLMSG_ERROR) {
++                      struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
++                      if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr)))
++                              bb_error_msg("ERROR truncated");
++                      else
++                              errno = -err->error;
++                      return -1;
++              }
++      }
+-      memset(&nladdr, 0, sizeof(nladdr));
+-      nladdr.nl_family = AF_NETLINK;
+-
+-      return xsendto(rth->fd, buf, len, (struct sockaddr*)&nladdr, sizeof(nladdr));
++      return 0;
+ }
+ int FAST_FUNC rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)
+--- a/networking/libiproute/libnetlink.h
++++ b/networking/libiproute/libnetlink.h
+@@ -20,7 +20,7 @@ struct rtnl_handle {
+ extern void xrtnl_open(struct rtnl_handle *rth) FAST_FUNC;
+ #define rtnl_close(rth) (close((rth)->fd))
+-extern int xrtnl_wilddump_request(struct rtnl_handle *rth, int fam, int type) FAST_FUNC;
++extern void xrtnl_wilddump_request(struct rtnl_handle *rth, int fam, int type) FAST_FUNC;
+ extern int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len) FAST_FUNC;
+ extern int xrtnl_dump_filter(struct rtnl_handle *rth,
+               int (*filter)(const struct sockaddr_nl*, struct nlmsghdr *n, void*) FAST_FUNC,
+@@ -34,8 +34,23 @@ extern int rtnl_talk(struct rtnl_handle
+               int (*junk)(struct sockaddr_nl *,struct nlmsghdr *n, void *),
+               void *jarg) FAST_FUNC;
+-extern int rtnl_send(struct rtnl_handle *rth, char *buf, int) FAST_FUNC;
++int rtnl_send_check(struct rtnl_handle *rth, const void *buf, int len) FAST_FUNC;
++//TODO: pass rth->fd instead of full rth?
++static ALWAYS_INLINE void rtnl_send(struct rtnl_handle *rth, const void *buf, int len)
++{
++      // Used to be:
++      //struct sockaddr_nl nladdr;
++      //memset(&nladdr, 0, sizeof(nladdr));
++      //nladdr.nl_family = AF_NETLINK;
++      //return xsendto(rth->fd, buf, len, (struct sockaddr*)&nladdr, sizeof(nladdr));
++      // iproute2-4.2.0 simplified the above to:
++      //return send(rth->fd, buf, len, 0);
++
++      // We are using even shorter:
++      xwrite(rth->fd, buf, len);
++      // and convert to void, inline.
++}
+ extern int addattr32(struct nlmsghdr *n, int maxlen, int type, uint32_t data) FAST_FUNC;
+ extern int addattr_l(struct nlmsghdr *n, int maxlen, int type, void *data, int alen) FAST_FUNC;