From 32773a99b1f0cf2b61b5f5a33359684b18aab1ed Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Fri, 13 May 2016 11:59:47 -0400 Subject: [PATCH] Avoid mounting /proc outside of selinux_init_load_policy(). Temporarily mounting /proc within selinuxfs_exists() can cause problems since it can be called by a libselinux constructor and therefore may be invoked by every program linked with libselinux. Since this was only motivated originally by a situation where selinuxfs_exists() was called from selinux_init_load_policy() before /proc was mounted, fix it in selinux_init_load_policy() instead. This reverts commit 5a8d8c499b2ef80eaa7b5abe2ec68d7101e613bf ("libselinux: only mount /proc if necessary") and commit 9df498884665d79474b79f0f30d1cd67df11bd3e ("libselinux: Mount procfs before checking /proc/filesystems"). Signed-off-by: Stephen Smalley --- libselinux/src/init.c | 27 +++------------------------ libselinux/src/load_policy.c | 15 ++++++++++----- 2 files changed, 13 insertions(+), 29 deletions(-) diff --git a/libselinux/src/init.c b/libselinux/src/init.c index 3530594..3c687a2 100644 --- libselinux/src/init.c +++ libselinux/src/init.c @@ -11,8 +11,6 @@ #include #include #include -#include -#include #include "dso.h" #include "policy.h" @@ -58,26 +56,15 @@ static int verify_selinuxmnt(const char *mnt) int selinuxfs_exists(void) { - int exists = 0, mnt_rc = -1, rc; - struct statfs sb; + int exists = 0; FILE *fp = NULL; char *buf = NULL; size_t len; ssize_t num; - 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) { - exists = 1; /* Fail as if it exists */ - goto out; - } - + if (!fp) + return 1; /* Fail as if it exists */ __fsetlocking(fp, FSETLOCKING_BYCALLER); num = getline(&buf, &len, fp); @@ -91,14 +78,6 @@ int selinuxfs_exists(void) free(buf); fclose(fp); - -out: -#ifndef MNT_DETACH -#define MNT_DETACH 2 -#endif - if (mnt_rc == 0) - umount2("/proc", MNT_DETACH); - return exists; } hidden_def(selinuxfs_exists) diff --git a/libselinux/src/load_policy.c b/libselinux/src/load_policy.c index 21ee58b..4f39fc7 100644 --- libselinux/src/load_policy.c +++ libselinux/src/load_policy.c @@ -17,6 +17,10 @@ #include "policy.h" #include +#ifndef MNT_DETACH +#define MNT_DETACH 2 +#endif + int security_load_policy(void *data, size_t len) { char path[PATH_MAX]; @@ -348,11 +352,6 @@ int selinux_init_load_policy(int *enforce) fclose(cfg); free(buf); } -#ifndef MNT_DETACH -#define MNT_DETACH 2 -#endif - if (rc == 0) - umount2("/proc", MNT_DETACH); /* * Determine the final desired mode. @@ -400,11 +399,17 @@ int selinux_init_load_policy(int *enforce) /* Only emit this error if selinux was not disabled */ fprintf(stderr, "Mount failed for selinuxfs on %s: %s\n", SELINUXMNT, strerror(errno)); } + + if (rc == 0) + umount2("/proc", MNT_DETACH); goto noload; } set_selinuxmnt(mntpoint); + if (rc == 0) + umount2("/proc", MNT_DETACH); + /* * Note: The following code depends on having selinuxfs * already mounted and selinuxmnt set above. -- 2.7.3