From: Craig Small <csmall@dropbear.xyz>
Date: Fri, 18 Mar 2022 21:51:22 +0000 (+1100)
Subject: fuser: Do not path check sockets
X-Git-Tag: v23.5rc1~6
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=43df1ce70db019f1e0598d083a9f0a955c93174d;p=psmisc

fuser: Do not path check sockets

The referenced commit fixed issue #10 where NFS servers have the same ID
and fuser could get confused. That fix was to do a path compare between
the user requested path and the path of the mount.

Block devices were skipped, because /dev/sda2 is not the same as /home
string-wise, even if sda2 was mounted as /home

The new issue is, sockets fail to match when using a mount point. That
is because "socket:[1547]" is not the same as
"/home/user/.gnupg/S.gpg-agent" string-wise, even if named socket 1547
uses that path.

The fix is to skip the path checks when looking at sockets. I'm not sure
if that means we will have confusion with named sockets that have a path
on NFS shares or not but I'm not sure there is a fix for those.

References:
 commit 5c979b38253d187a8ecb8e52a0878b8bb668894f
 psmisc/psmisc#35
---

diff --git a/ChangeLog b/ChangeLog
index 5d90a87..9893085 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,7 @@ Changes in NEXT
 ===============
 	* killall: Check truncated names !28
 	* killall: Use openat and pidfd_send_signal #37
+	* killall: Don't check paths of sockets #35
         * pstree: Check for process with show_parents #38
 	* pstree: Don't disable compaction with show pgids #34
 	* pstree: Fix storage leak !29
diff --git a/Makefile.am b/Makefile.am
index 8067689..3590afa 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -110,3 +110,11 @@ dist-hook:
 get-trans:
 	rsync -Lrtvz  translationproject.org::tp/latest/psmisc/  po
 	rsync -Lrtvz  translationproject.org::tp/latest/psmisc-man/  man-po
+
+# Programs required for testing only
+check_PROGRAMS = \
+	src/socket_test
+
+src_socket_test_SOURCES = src/socket_test.c
+
+check: $(check_PROGRAMS)
diff --git a/src/.gitignore b/src/.gitignore
index 6068ef7..a0653ce 100644
--- a/src/.gitignore
+++ b/src/.gitignore
@@ -7,3 +7,4 @@ prtstat
 pslog
 pstree
 signames.h
+socket_test
diff --git a/src/fuser.c b/src/fuser.c
index 1e0d286..4d4363c 100644
--- a/src/fuser.c
+++ b/src/fuser.c
@@ -1681,8 +1681,9 @@ static void check_dir(
                 if (thedev != dev_tmp->device)
                     continue;
 
-                /* check the paths match if it is not a block device */
-                if (! S_ISBLK(dev_tmp->name->st.st_mode))
+                /* check the paths match if it is not a block device or socket */
+                if (! S_ISBLK(dev_tmp->name->st.st_mode)
+                    && !S_ISSOCK(st.st_mode))
                 {
                     if (readlink(filepath, real_filepath, PATH_MAX-1) < 0)
                     {
diff --git a/src/socket_test.c b/src/socket_test.c
new file mode 100644
index 0000000..ac6ebec
--- /dev/null
+++ b/src/socket_test.c
@@ -0,0 +1,55 @@
+/*
+ * Creates named and anonymous sockets to test fuser
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
+int main(int argc, char *argv[])
+{
+    int skt;
+    struct sockaddr_un name;
+
+    if (argc < 2)
+    {
+        fprintf(stderr, "Usage:\n%s <socketpath>\n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+
+    if ( (skt = socket(AF_UNIX, SOCK_SEQPACKET, 0)) < 0)
+    {
+        perror("socket");
+        exit(EXIT_FAILURE);
+    }
+
+    memset(&name, 0, sizeof(name));
+
+    name.sun_family = AF_UNIX;
+    strncpy(name.sun_path, argv[1], sizeof(name.sun_path) -1);
+    
+    if ( bind(skt, (const struct sockaddr *) &name, sizeof name) < 0)
+    {
+        perror("bind");
+        exit(EXIT_FAILURE);
+    }
+
+    if ( listen(skt, 5) < 0)
+    {
+        perror("listen");
+        exit(EXIT_FAILURE);
+    }
+
+    if ( accept(skt, NULL, NULL) < 0)
+    {
+        perror("accept");
+        exit(EXIT_FAILURE);
+    }
+
+//    sleep(100);
+    exit(EXIT_SUCCESS);
+}
+
diff --git a/testsuite/config/unix.exp b/testsuite/config/unix.exp
index 27e6382..cfa1777 100644
--- a/testsuite/config/unix.exp
+++ b/testsuite/config/unix.exp
@@ -30,3 +30,23 @@ proc expect_nothing { test } {
     	eof { pass "$test" }
 	}
 }
+
+proc kill_process pid {
+    set cmdline "kill $pid"
+    if { [catch { exec /bin/sh -c $cmdline } msg]} {
+        warning "Could not kill process: $msg\n"
+    }
+}
+
+proc make_socketproc { sktpath } {
+    global topdir socketproc_pid socketproc_spawnid testsocket_path
+
+    set testproc_realpath "${topdir}/src/socket_test"
+    set socketproc_pid [ spawn $testproc_realpath $sktpath ]
+}
+
+proc kill_socketproc { } {
+    global socketproc_pid
+    kill_process $socketproc_pid
+}
+
diff --git a/testsuite/fuser.test/fuser.exp b/testsuite/fuser.test/fuser.exp
index 5c6a0c0..aac5947 100644
--- a/testsuite/fuser.test/fuser.exp
+++ b/testsuite/fuser.test/fuser.exp
@@ -39,4 +39,23 @@ set test "fuser -l"
 spawn $fuser -l
 expect_pass "$test" "^(\[A-Z12\]+\\s*)+$"
 
+# Create test process to make named unix socket
+# Needs a sleep otherwise the socket won't be
+# available before the file exists comes along
+set testsocket_path [ exec mktemp -u -p /tmp ]
+make_socketproc ${testsocket_path}
+sleep 1
+
+if {[file exists ${testsocket_path} ]} {
+  set test "fuser find socket from path"
+  spawn sh -c "$fuser -v $testsocket_path"
+  expect_pass "$test" "$socketproc_pid F"
+
+  set test "fuser find socket from mount"
+  spawn sh -c "$fuser -mv /tmp"
+  expect_pass "$test" "$socketproc_pid F"
+} else {
+  unsupported "fuser tests using named sockets"
+}
+kill_socketproc