diff options
Diffstat (limited to 'debian/patches-applied/pam-limits-nofile-fd-setsize-cap')
| -rw-r--r-- | debian/patches-applied/pam-limits-nofile-fd-setsize-cap | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/debian/patches-applied/pam-limits-nofile-fd-setsize-cap b/debian/patches-applied/pam-limits-nofile-fd-setsize-cap new file mode 100644 index 0000000..9c0503c --- /dev/null +++ b/debian/patches-applied/pam-limits-nofile-fd-setsize-cap @@ -0,0 +1,60 @@ +From: Robie Basak <robie.basak@ubuntu.com> +Subject: pam_limits: cap the default soft nofile limit read from pid 1 to FD_SETSIZE + +Cap the default soft nofile limit read from pid 1 to FD_SETSIZE since +larger values can cause problems with fd_set overflow and systemd sets +itself higher. + +See: +https://lists.ubuntu.com/archives/ubuntu-devel/2010-September/031446.html +http://www.outflux.net/blog/archives/2014/06/13/5-year-old-glibc-select-weakness-fixed/ +https://sourceware.org/bugzilla/show_bug.cgi?id=10352 +https://github.com/systemd/systemd/commit/4096d6f5879aef73e20dd7b62a01f447629945b0 + +pam_limits reads the default limits from /proc/1/limits. Previously, +using upstart, this resulted in a 1024 nofile soft limit on Ubuntu +systems by default. Using systemd, this results in a limit of 65536 +instead. This is not the intention of systemd upstream. See systemd +commit 4096d6f for an explanation of systemd's behaviour. + +If we want to make such a change to the default distribution soft limit +in PAM, we should do it deliberately and carefully, not accidentally. A +change should consider what uses select(2) and might inadvertently (and +incorrectly) assume that file descriptors will always fit into an +fd_set, what vulnerabilities or crashes the change could consequently +create, and whether the protection now present with FORTIFY_SOURCE is +suitably enabled in all relevant builds. + +So this keeps the soft limit at 1024 for now. The hard limit will rise +to 65536 along with systemd. Anything that knows that it will not be +buggy with respect to fd_set and FD_SETSIZE, such as by using poll(2) or +epoll(7) instead of select(2), can always raise the soft limit itself +without issue. + +20:54 <rbasak> slangasek: [...] I'm also not sure how to go about +upstreaming this as pam_limits seems to be heavily patched already. + +Forwarded: no +Reviewed-by: Adam Conrad <adconrad@ubuntu.com> +Reviewed-by: Martin Pitt <martin.pitt@ubuntu.com> +Last-Update: 2015-04-22 + +Index: pam/modules/pam_limits/pam_limits.c +=================================================================== +--- pam.orig/modules/pam_limits/pam_limits.c ++++ pam/modules/pam_limits/pam_limits.c +@@ -450,6 +450,14 @@ + pl->limits[i].src_hard = LIMITS_DEF_KERNEL; + } + fclose(limitsfile); ++ ++ /* Cap the default soft nofile limit read from pid 1 to FD_SETSIZE ++ * since larger values can cause problems with fd_set overflow and ++ * systemd sets itself higher. */ ++ if (pl->limits[RLIMIT_NOFILE].src_soft == LIMITS_DEF_KERNEL && ++ pl->limits[RLIMIT_NOFILE].limit.rlim_cur > FD_SETSIZE) { ++ pl->limits[RLIMIT_NOFILE].limit.rlim_cur = FD_SETSIZE; ++ } + } + + static int init_limits(pam_handle_t *pamh, struct pam_limit_s *pl, int ctrl) |