forked from ports/contrib
pam_xdg: strip to minimum (cannot track sessions via PAM), thus graceful
This commit is contained in:
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28d6763c03
commit
f2193cf1ac
@ -1,7 +1,7 @@
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untrusted comment: verify with /etc/ports/contrib.pub
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RWSagIOpLGJF3yVeUzlfQ7+UJq2gIuabqKJqhiWq7h2/UY5x8mlWVY7NEag9ndV9ypuodnfpLrP0QWzNjqO3eRJ1b5zTk3MRnAs=
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SHA256 (Pkgfile) = e1b2ba87fd768518b4f81f3f9fb1fcce6780b2538cded18600564532e86f6a05
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RWSagIOpLGJF3/opxnSlpIKUNMt7/zCoADPQ4PYlOmbd2GckIrSxOZvjqNNRaw5n+mhVd/iOl35BH6C2CIKF12kK6df2J7zZ4Q8=
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SHA256 (Pkgfile) = ac39f667ad9c2778b25753a6265ef2705335afb9b5cde1f70d9cb86f9ee22076
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SHA256 (.footprint) = 56d789b652e6167f5fb93e1e6d48243e13f598c6d9a72705a8e54a003574ba31
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SHA256 (pam_xdg.c) = 9125ac3749b087f78844953a1a43790055a62efa0b8c25bd8766e35b061ca58c
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SHA256 (pam_xdg.8) = 0f19e9f2437c6d0cb24465798ded6d6a3b2be07c012ee611648a4e4f1a21bbf1
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SHA256 (pam_xdg.c) = 81bfedeb798bc63d33f2b44874df0d796b439e93876a4a41f94d1ee26a001c38
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SHA256 (pam_xdg.8) = 2929bcd6655d28127d386215d3d8c4fed6744b65c4866ac7e49d54cb438d9133
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SHA256 (makefile) = 2466f499c3e84fd821176371fa9ff78143bf94b9ec09fd9e654b35613e4ead7d
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@ -3,7 +3,7 @@
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# Maintainer: Steffen Nurpmeso, steffen at sdaoden dot eu
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name=pam_xdg
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version=20210130
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version=20210131
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release=1
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source=($name.c $name.8 makefile)
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@ -15,7 +15,7 @@
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.
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.Dd January 30, 2021
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.Dd January 31, 2021
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.Dt PAM_XDG 8
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.Os
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.
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@ -35,7 +35,7 @@
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.Sh DESCRIPTION
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.
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.Nm
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is a PAM module that manages creation and deletion of the
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is a PAM module that manages creation of the
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.Ev XDG_RUNTIME_DIR
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directory, as well as injection of environment variables denoting all
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directories specified by the
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@ -44,19 +44,17 @@ spec/\:basedir-\:spec-\:latest.html "XDG Base Directory Specification"
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into user sessions.
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.
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.Pp
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When linked into the PAM system, the runtime directory will be created as
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.Ql /run/user/`id -u`
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once a user creates his or her first login session, and it will be
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removed recursively once the last such session ends.
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When linked into the PAM session system the runtime directory will be
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created once a user creates his or her first login session.
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Unless
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.Ar rundir
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was given all XDG related environment variables will be created in the
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user session with their default or computed values, otherwise only
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was given all XDG related environment variables will be created in all
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user sessions with their default or computed values, otherwise only
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.Ev XDG_RUNTIME_DIR .
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If
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.Ar notroot
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was given the module will bypass itself for root account logins, that
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is, no actions will be performed.
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was given the module will bypass itself for root account logins and
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perform no actions for root.
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.
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.Pp
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In order to make use of this script, place the following in the control
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@ -1,14 +1,12 @@
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/*@ pam_xdg - manage XDG Base Directories (runtime dir life time, environment).
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*@ Create /run/user/`id -u` when the first session is opened, and remove it
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*@ again once the last is closed.
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*@ Create /run/user/`id -u` when the first session is opened.
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*@ It also creates according XDG_RUNTIME_DIR etc. environment variables in the
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*@ user sessions, except when given the "runtime" option, in which case it
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*@ only creates XDG_RUNTIME_DIR and not the others.
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*@ Place for example in /etc/pam.d/common-session one of the following:
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*@ session options pam_xdg.so [runtime] [notroot]
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*@ Notes: - effectively needs ISO C99 as it uses strtoull(3).
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*@ - according to XDG Base Directory Specification, v0.7.
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*@ - Linux.
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*@ Notes: - according to XDG Base Directory Specification, v0.7.
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*@ - Linux-only (i think).
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*
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* Copyright (c) 2021 Steffen Nurpmeso <steffen@sdaoden.eu>.
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* SPDX-License-Identifier: ISC
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@ -37,13 +35,9 @@
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/* */
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#define a_XDG "pam_xdg"
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#define a_RUNTIME_DIR_OUTER "/run" /* This must exist already */
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#define a_RUNTIME_DIR_OUTER "/run" /* This must exist already */
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#define a_RUNTIME_DIR_BASE "user" /* We create this as necessary, thus. */
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#define a_LOCK_FILE "." a_XDG ".lck"
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#define a_LOCK_TRIES 10
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#define a_DAT_FILE "." a_XDG ".dat"
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#define a_RUNTIME_DIR_BASE_MODE 0755 /* 0711? */
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/* >8 -- 8< */
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@ -55,13 +49,10 @@
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <pwd.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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@ -82,23 +73,19 @@ static int a_xdg(int isopen, pam_handle_t *pamh, int flags, int argc,
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static int
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a_xdg(int isopen, pam_handle_t *pamh, int flags, int argc, const char **argv){
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char uidbuf[sizeof "18446744073709551615"],
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wbuf[(((sizeof("18446744073709551615") -1) * 2) |
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(sizeof("cd ..;rm -rf ") + sizeof("18446744073709551615")) |
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(sizeof("XDG_RUNTIME_DIR=") + sizeof(a_RUNTIME_DIR_OUTER) +
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wbuf[((sizeof("XDG_RUNTIME_DIR=") + sizeof(a_RUNTIME_DIR_OUTER) +
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sizeof(a_RUNTIME_DIR_BASE) + sizeof("18446744073709551615")) |
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(sizeof("XDG_CONFIG_DIRS=") + PATH_MAX)
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) +1];
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struct flock flp;
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struct stat st;
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uint64_t sessions;
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struct passwd *pwp;
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char const *emsg;
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int cntrlfd, fd, cwdfd, only_runtime, notroot, res, uidbuflen;
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int cwdfd, only_runtime, notroot, res, uidbuflen;
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char const *user;
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(void)flags;
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user = "<unset>";
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cntrlfd = fd = cwdfd = -1;
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cwdfd = -1;
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only_runtime = notroot = 0;
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/* Command line */
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@ -114,7 +101,8 @@ a_xdg(int isopen, pam_handle_t *pamh, int flags, int argc, const char **argv){
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goto jerr;
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}
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}
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}
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}else
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goto jok; /* No longer used, session counting does not work */
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/* We need the user we go for */
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if((res = pam_get_item(pamh, PAM_USER, (void const**)&user)
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@ -143,7 +131,7 @@ a_xdg(int isopen, pam_handle_t *pamh, int flags, int argc, const char **argv){
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}
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/* We try create the base directory once as necessary */
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if(isopen){
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/*if(isopen)*/{
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res = 0;
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while(fstatat(cwdfd, a_RUNTIME_DIR_BASE, &st, AT_SYMLINK_NOFOLLOW
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) == -1){
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@ -153,7 +141,7 @@ a_xdg(int isopen, pam_handle_t *pamh, int flags, int argc, const char **argv){
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goto jerr;
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}
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if(mkdirat(cwdfd, a_RUNTIME_DIR_BASE, 0711) == -1){
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if(mkdirat(cwdfd, a_RUNTIME_DIR_BASE, a_RUNTIME_DIR_BASE_MODE) == -1){
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emsg = "cannot create base directory "
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a_RUNTIME_DIR_OUTER "/" a_RUNTIME_DIR_BASE;
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goto jerr;
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@ -170,148 +158,47 @@ a_xdg(int isopen, pam_handle_t *pamh, int flags, int argc, const char **argv){
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close(cwdfd);
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cwdfd = res;
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/* Landed in the runtime base dir, obtain our lock */
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if((cntrlfd = openat(cwdfd, a_LOCK_FILE,
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(O_CREAT | O_WRONLY | O_NOFOLLOW | O_NOCTTY),
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(S_IRUSR | S_IWUSR))) == -1){
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emsg = "cannot open control lock file";
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goto jerr;
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}
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for(res = a_LOCK_TRIES;;){
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memset(&flp, 0, sizeof flp);
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flp.l_type = F_WRLCK;
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flp.l_start = 0;
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flp.l_whence = SEEK_SET;
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flp.l_len = 0;
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if(fcntl(cntrlfd, F_SETLKW, &flp) != -1)
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break;
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if(errno != EINTR){
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emsg = "unexpected error obtaining lock on control lock file";
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goto jerr;
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}
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if(--res == 0){
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emsg = "cannot obtain lock on control lock file";
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goto jerr;
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}
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}
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/* Turn to user management */
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uidbuflen = snprintf(uidbuf, sizeof(uidbuf), "%lu",
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(unsigned long)pwp->pw_uid);
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/* We create the per-user directory on isopen time as necessary */
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for(res = 0;; ++res){
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int nfd;
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/*if(isopen)*/{
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for(res = 0;; ++res){
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int nfd;
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if((nfd = openat(cwdfd, uidbuf, (O_PATH | O_DIRECTORY | O_NOFOLLOW))
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) != -1){
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close(cwdfd);
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cwdfd = nfd;
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break;
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}else{
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if(errno == ENOENT){
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if(!isopen)
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goto jok;
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if(res != 0)
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goto jeurd;
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}else{
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jeurd:
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emsg = "per user XDG_RUNTIME_DIR not accessible";
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goto jerr;
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}
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}
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if(mkdirat(cwdfd, uidbuf, 0700) == -1){
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emsg = "cannot create per user XDG_RUNTIME_DIR";
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goto jerr;
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}
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if(fchownat(cwdfd, uidbuf, pwp->pw_uid, pwp->pw_gid, AT_SYMLINK_NOFOLLOW
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) == -1){
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emsg = "cannot chown(2) per user XDG_RUNTIME_DIR";
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goto jerr;
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}
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}
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/* Read session counter; be simple and assume 0 if non-existent, this should
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* not happen in practice */
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sessions = 0;
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if((fd = openat(cwdfd, a_DAT_FILE, O_RDONLY)) != -1){
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char *ep;
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ssize_t r;
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while((r = read(fd, wbuf, sizeof(wbuf) -1)) == -1){
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if(errno != EINTR){
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emsg = "I/O error while reading session counter";
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goto jerr;
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}
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}
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/* We have written this as a valid POSIX text file, then, so chop tail */
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if(r < 1 || (size_t)r >= (sizeof(wbuf) -1) / 2){
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jecnt:
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emsg = "session counter corrupted, ask administrator to remove "
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a_RUNTIME_DIR_OUTER "/" a_RUNTIME_DIR_BASE "/YOUR-UID/"
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a_DAT_FILE;
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goto jerr;
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}
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for(;;){
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char c;
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c = wbuf[(size_t)r - 1];
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if(c == '\0' || c == '\n'){
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if(--r == 0)
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goto jecnt;
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}else
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if((nfd = openat(cwdfd, uidbuf, (O_PATH | O_DIRECTORY | O_NOFOLLOW))
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) != -1){
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close(cwdfd);
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cwdfd = nfd;
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break;
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}else{
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if(errno == ENOENT){
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if(!isopen)
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goto jok;
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if(res != 0)
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goto jeurd;
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}else{
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jeurd:
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emsg = "per user XDG_RUNTIME_DIR not accessible";
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goto jerr;
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}
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}
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if(mkdirat(cwdfd, uidbuf, 0700) == -1){
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emsg = "cannot create per user XDG_RUNTIME_DIR";
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goto jerr;
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}
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if(fchownat(cwdfd, uidbuf, pwp->pw_uid, pwp->pw_gid,
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AT_SYMLINK_NOFOLLOW) == -1){
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emsg = "cannot chown(2) per user XDG_RUNTIME_DIR";
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goto jerr;
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}
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}
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wbuf[(size_t)r] = '\0';
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sessions = strtoull(wbuf, &ep, 10);
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if(sessions == ULLONG_MAX || ep == wbuf || *ep != '\0')
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goto jecnt;
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close(fd);
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fd = -1;
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}
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if(isopen)
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++sessions;
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/* == 0 should never happen, but just handled it easily */
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else if(sessions == 0 || --sessions == 0){
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/* This is ridiculously simple, but everything else would be opposite */
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char const cmd[] = "rm -rf " a_RUNTIME_DIR_OUTER "/"
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a_RUNTIME_DIR_BASE "/";
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memcpy(wbuf, cmd, sizeof(cmd) -1);
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memcpy(&wbuf[sizeof(cmd) -1], uidbuf, uidbuflen +1);
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res = system(wbuf);
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if(!WIFEXITED(res) || WEXITSTATUS(res) != 0){
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emsg = "unable to rm(1) -rf per user XDG_RUNTIME_DIR";
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errno = EINVAL;
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goto jerr;
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}
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goto jok;
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}
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/* Write out session counter (as a valid POSIX text file) */
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res = snprintf(wbuf, sizeof wbuf, "%llu\n", (unsigned long long)sessions);
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if(((fd = openat(cwdfd, a_DAT_FILE,
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(O_CREAT | O_TRUNC | O_WRONLY | O_SYNC | O_NOFOLLOW | O_NOCTTY),
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(S_IRUSR | S_IWUSR))) == -1) || write(fd, wbuf, res) != res){
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emsg = "cannot write session counter, ask administrator to remove "
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a_RUNTIME_DIR_OUTER "/" a_RUNTIME_DIR_BASE "/YOUR-UID/"
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a_DAT_FILE;
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goto jerr;
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}
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close(fd);
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fd = -1;
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/* When opening, we want to put environment variables, too */
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if(isopen){
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/*if(isopen)*/{
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char *cp;
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/* XDG_RUNTIME_DIR */
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@ -374,10 +261,6 @@ jecnt:
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jok:
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res = PAM_SUCCESS;
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jleave:
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if(fd != -1)
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close(fd);
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if(cntrlfd != -1)
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close(cntrlfd);
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if(cwdfd != -1)
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close(cwdfd);
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