automount(8) uses a flag file if it needs to check for multiple
invocations of itself at startup.
The check to see if a flag file is owned by an existing automount(8)
process can return a false positive because it doesn't also check the
name of the executable of the given pid.
Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
Reported-by: Doron Cohen <doron@xxxxxxx>
---
CHANGELOG | 1 +
daemon/flag.c | 35 +++++++++++++++++++++++++++++++++++
2 files changed, 36 insertions(+)
diff --git a/CHANGELOG b/CHANGELOG
index af8b099c..1b5c69ee 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -17,6 +17,7 @@ xx/xx/2017 autofs-5.1.4
- add some more debug logging to get_nfs_info().
- add some more debug logging to get_supported_ver_and_cost().
- fix ipv6 proto option handling.
+- also check flag file exe name.
24/05/2017 autofs-5.1.3
=======================
diff --git a/daemon/flag.c b/daemon/flag.c
index db9a4bde..99f26847 100644
--- a/daemon/flag.c
+++ b/daemon/flag.c
@@ -33,12 +33,43 @@
#define MAX_PIDSIZE 20
#define FLAG_FILE AUTOFS_FLAG_DIR "/autofs-running"
+#define EXE_SELF "/proc/self/exe"
+#define EXE_PID "/proc/%u/exe"
+
/* Flag for already existing flag file. */
static int we_created_flagfile = 0;
/* file descriptor of flag file */
static int fd = -1;
+static int check_pid_exe_name(pid_t pid)
+{
+ char self_name[PATH_MAX + 1];
+ char pid_name[PATH_MAX + 1];
+ char exe_pid[MAX_PIDSIZE + 1];
+ int len, ret = 0;
+
+ len = readlink(EXE_SELF, self_name, PATH_MAX);
+ if (len == -1 || len == PATH_MAX)
+ goto out;
+ else
+ self_name[len] = 0;
+
+ len = snprintf(exe_pid, MAX_PIDSIZE, EXE_PID, pid);
+ if (len >= MAX_PIDSIZE)
+ goto out;
+
+ len = readlink(exe_pid, pid_name, PATH_MAX);
+ if (len == -1 || len == PATH_MAX)
+ goto out;
+ else
+ pid_name[len] = 0;
+
+ ret = !strcmp(self_name, pid_name);
+out:
+ return ret;
+}
+
static int flag_is_owned(int fd)
{
int pid = 0, tries = 3;
@@ -83,6 +114,10 @@ static int flag_is_owned(int fd)
*/
if (ret == -1 && errno == ESRCH)
return 0;
+
+ /* If there is a process check if it is automount */
+ if (!check_pid_exe_name(pid))
+ return 0;
} else {
/*
* Odd, no pid in file - so what should we do?
--
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