From 5a8d8c499b2ef80eaa7b5abe2ec68d7101e613bf Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Mon, 29 Feb 2016 10:10:55 -0500 Subject: [PATCH] libselinux: only mount /proc if necessary Commit 9df498884665d ("libselinux: Mount procfs before checking /proc/filesystems") changed selinuxfs_exists() to always try mounting /proc before reading /proc/filesystems. However, this is unnecessary if /proc is already mounted and can produce avc denials if the process is not allowed to perform the mount. Check first to see if /proc is already present and only try the mount if it is not. Signed-off-by: Stephen Smalley --- libselinux/src/init.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/libselinux/src/init.c b/libselinux/src/init.c index 3db4de0..3530594 100644 --- libselinux/src/init.c +++ libselinux/src/init.c @@ -12,6 +12,7 @@ #include #include #include +#include #include "dso.h" #include "policy.h" @@ -57,13 +58,19 @@ static int verify_selinuxmnt(const char *mnt) int selinuxfs_exists(void) { - int exists = 0, mnt_rc = 0; + int exists = 0, mnt_rc = -1, rc; + struct statfs sb; FILE *fp = NULL; char *buf = NULL; size_t len; ssize_t num; - mnt_rc = mount("proc", "/proc", "proc", 0, 0); + do { + rc = statfs("/proc", &sb); + } while (rc < 0 && errno == EINTR); + + if (rc == 0 && ((uint32_t)sb.f_type != (uint32_t)PROC_SUPER_MAGIC)) + mnt_rc = mount("proc", "/proc", "proc", 0, 0); fp = fopen("/proc/filesystems", "r"); if (!fp) { -- 2.7.3