| Message ID | 20240918165030.3914855-1-nicolas.dichtel@6wind.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 57daf8ff8c6c357a5a083657e5b03d2883cbc4f9 |
| Delegated to: | Stephen Hemminger |
| Headers | show |
| Series | [iproute2,v2] iplink: fix fd leak when playing with netns | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
Hello: This patch was applied to iproute2/iproute2.git (main) by Stephen Hemminger <stephen@networkplumber.org>: On Wed, 18 Sep 2024 18:49:41 +0200 you wrote: > The command 'ip link set foo netns mynetns' opens a file descriptor to fill > the netlink attribute IFLA_NET_NS_FD. This file descriptor is never closed. > When batch mode is used, the number of file descriptor may grow greatly and > reach the maximum file descriptor number that can be opened. > > This fd can be closed only after the netlink answer. Moreover, a second > fd could be opened because some (struct link_util)->parse_opt() handlers > call iplink_parse(). > > [...] Here is the summary with links: - [iproute2,v2] iplink: fix fd leak when playing with netns https://git.kernel.org/pub/scm/network/iproute2/iproute2.git/commit/?id=57daf8ff8c6c You are awesome, thank you!
diff --git a/include/utils.h b/include/utils.h index a2a98b9bf17d..f044b3401320 100644 --- a/include/utils.h +++ b/include/utils.h @@ -395,4 +395,7 @@ const char *proto_n2a(unsigned short id, char *buf, int len, FILE *generic_proc_open(const char *env, const char *name); +int open_fds_add(int fd); +void open_fds_close(void); + #endif /* __UTILS_H__ */ diff --git a/ip/iplink.c b/ip/iplink.c index 3bc75d243719..0dd83ff44846 100644 --- a/ip/iplink.c +++ b/ip/iplink.c @@ -622,9 +622,11 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req, char **type) if (netns != -1) duparg("netns", *argv); netns = netns_get_fd(*argv); - if (netns >= 0) + if (netns >= 0) { + open_fds_add(netns); addattr_l(&req->n, sizeof(*req), IFLA_NET_NS_FD, &netns, 4); + } else if (get_integer(&netns, *argv, 0) == 0) addattr_l(&req->n, sizeof(*req), IFLA_NET_NS_PID, &netns, 4); @@ -1088,6 +1090,8 @@ static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv) else ret = rtnl_talk(&rth, &req.n, NULL); + open_fds_close(); + if (ret) return -2; diff --git a/lib/utils.c b/lib/utils.c index deb7654a0b01..98c06ab6a652 100644 --- a/lib/utils.c +++ b/lib/utils.c @@ -40,6 +40,9 @@ int timestamp_short; int pretty; const char *_SL_ = "\n"; +static int open_fds[5]; +static int open_fds_cnt; + static int af_byte_len(int af); static void print_time(char *buf, int len, __u32 time); static void print_time64(char *buf, int len, __s64 time); @@ -2017,3 +2020,23 @@ FILE *generic_proc_open(const char *env, const char *name) return fopen(p, "r"); } + +int open_fds_add(int fd) +{ + if (open_fds_cnt >= ARRAY_SIZE(open_fds)) + return -1; + + open_fds[open_fds_cnt++] = fd; + return 0; +} + + +void open_fds_close(void) +{ + int i; + + for (i = 0; i < open_fds_cnt; i++) + close(open_fds[i]); + + open_fds_cnt = 0; +}
The command 'ip link set foo netns mynetns' opens a file descriptor to fill the netlink attribute IFLA_NET_NS_FD. This file descriptor is never closed. When batch mode is used, the number of file descriptor may grow greatly and reach the maximum file descriptor number that can be opened. This fd can be closed only after the netlink answer. Moreover, a second fd could be opened because some (struct link_util)->parse_opt() handlers call iplink_parse(). Let's add a helper to manage these fds: - open_fds_add() stores a fd, up to 5 (arbitrary choice, it seems enough); - open_fds_close() closes all stored fds. Fixes: 0dc34c7713bb ("iproute2: Add processless network namespace support") Reported-by: Alexandre Ferrieux <alexandre.ferrieux@orange.com> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> --- v1 -> v2: - use a global variable to store fds include/utils.h | 3 +++ ip/iplink.c | 6 +++++- lib/utils.c | 23 +++++++++++++++++++++++ 3 files changed, 31 insertions(+), 1 deletion(-)