[lxc-devel] [lxc/master] utils: tweak lxc_mount_proc_if_needed()

[brauner on Github]

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From 943144d9316a2d890823c214306214637dbe2fa2 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at ubuntu.com>
Date: Fri, 28 Apr 2017 23:54:24 +0200
Subject: [PATCH 1/2] conf: non-functional changes

Closes #1475.

Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>
---
 src/lxc/conf.c  | 15 ++++++++-------
 src/lxc/utils.c |  2 +-
 src/lxc/utils.h |  2 +-
 3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index eb92b5c..5d47406 100644
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -3760,20 +3760,21 @@ int ttys_shift_ids(struct lxc_conf *c)
 	return 0;
 }
 
-/* NOTE: not to be called from inside the container namespace! */
-int tmp_proc_mount(struct lxc_conf *lxc_conf)
+/* NOTE: Must not be called from inside the container namespace! */
+int lxc_create_tmp_proc_mount(struct lxc_conf *conf)
 {
 	int mounted;
 
-	mounted = mount_proc_if_needed(lxc_conf->rootfs.path ? lxc_conf->rootfs.mount : "");
+	mounted = lxc_mount_proc_if_needed(conf->rootfs.path ? conf->rootfs.mount : "");
 	if (mounted == -1) {
-		SYSERROR("failed to mount /proc in the container.");
+		SYSERROR("failed to mount /proc in the container");
 		/* continue only if there is no rootfs */
-		if (lxc_conf->rootfs.path)
+		if (conf->rootfs.path)
 			return -1;
 	} else if (mounted == 1) {
-		lxc_conf->tmp_umount_proc = 1;
+		conf->tmp_umount_proc = 1;
 	}
+
 	return 0;
 }
 
@@ -4063,7 +4064,7 @@ int lxc_setup(struct lxc_handler *handler)
 	}
 
 	/* mount /proc if it's not already there */
-	if (tmp_proc_mount(lxc_conf) < 0) {
+	if (lxc_create_tmp_proc_mount(lxc_conf) < 0) {
 		ERROR("failed to LSM mount proc for '%s'", name);
 		return -1;
 	}
diff --git a/src/lxc/utils.c b/src/lxc/utils.c
index d83e294..03386dd 100644
--- a/src/lxc/utils.c
+++ b/src/lxc/utils.c
@@ -1754,7 +1754,7 @@ int safe_mount(const char *src, const char *dest, const char *fstype,
  *
  * NOTE: not to be called from inside the container namespace!
  */
-int mount_proc_if_needed(const char *rootfs)
+int lxc_mount_proc_if_needed(const char *rootfs)
 {
 	char path[MAXPATHLEN];
 	char link[20];
diff --git a/src/lxc/utils.h b/src/lxc/utils.h
index b6fc7c5..161788f 100644
--- a/src/lxc/utils.h
+++ b/src/lxc/utils.h
@@ -326,7 +326,7 @@ char *get_template_path(const char *t);
 int setproctitle(char *title);
 int safe_mount(const char *src, const char *dest, const char *fstype,
 		unsigned long flags, const void *data, const char *rootfs);
-int mount_proc_if_needed(const char *rootfs);
+int lxc_mount_proc_if_needed(const char *rootfs);
 int open_devnull(void);
 int set_stdfds(int fd);
 int null_stdfds(void);

From fc2ad9dcdd756452694b523b39acf6e369fc282b Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at ubuntu.com>
Date: Sat, 29 Apr 2017 00:03:06 +0200
Subject: [PATCH 2/2] utils: tweak lxc_mount_proc_if_needed()

Create /proc directory if it doesn't exist.

Closes #1475.

Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>
---
 src/lxc/utils.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/src/lxc/utils.c b/src/lxc/utils.c
index 03386dd..6458bbd 100644
--- a/src/lxc/utils.c
+++ b/src/lxc/utils.c
@@ -1766,37 +1766,48 @@ int lxc_mount_proc_if_needed(const char *rootfs)
 		SYSERROR("proc path name too long");
 		return -1;
 	}
+
 	memset(link, 0, 20);
 	linklen = readlink(path, link, 20);
 	mypid = (int)getpid();
-	INFO("I am %d, /proc/self points to '%s'", mypid, link);
+	INFO("I am %d, /proc/self points to \"%s\"", mypid, link);
+
 	ret = snprintf(path, MAXPATHLEN, "%s/proc", rootfs);
 	if (ret < 0 || ret >= MAXPATHLEN) {
 		SYSERROR("proc path name too long");
 		return -1;
 	}
-	if (linklen < 0) /* /proc not mounted */
+
+	/* /proc not mounted */
+	if (linklen < 0) {
+		if (mkdir(path, 0755) && errno != EEXIST)
+			return -1;
 		goto domount;
+	}
+
 	if (lxc_safe_int(link, &link_to_pid) < 0)
 		return -1;
+
+	/* wrong /procs mounted */
 	if (link_to_pid != mypid) {
-		/* wrong /procs mounted */
-		umount2(path, MNT_DETACH); /* ignore failure */
+		/* ignore failure */
+		umount2(path, MNT_DETACH);
 		goto domount;
 	}
+
 	/* the right proc is already mounted */
 	return 0;
 
 domount:
-	if (!strcmp(rootfs,"")) /* rootfs is NULL */
+	/* rootfs is NULL */
+	if (!strcmp(rootfs,""))
 		ret = mount("proc", path, "proc", 0, NULL);
 	else
 		ret = safe_mount("proc", path, "proc", 0, NULL, rootfs);
-
 	if (ret < 0)
 		return -1;
 
-	INFO("Mounted /proc in container for security transition");
+	INFO("mounted /proc in container for security transition");
 	return 1;
 }