From 3aee60181b0673be7b1562899869607238b2d30f Mon Sep 17 00:00:00 2001 From: =?utf8?q?Fabian=20Gr=C3=BCnbichler?= Date: Tue, 7 Aug 2018 11:39:50 +0200 Subject: [PATCH] cherry-pick CVE-2018-6556 fix from upstream's stable-3.0 branch --- ...6556-verify-netns-fd-in-lxc-user-nic.patch | 115 ++++++++++++++++++ debian/patches/series | 1 + 2 files changed, 116 insertions(+) create mode 100644 debian/patches/extra/0013-CVE-2018-6556-verify-netns-fd-in-lxc-user-nic.patch diff --git a/debian/patches/extra/0013-CVE-2018-6556-verify-netns-fd-in-lxc-user-nic.patch b/debian/patches/extra/0013-CVE-2018-6556-verify-netns-fd-in-lxc-user-nic.patch new file mode 100644 index 0000000..33698b6 --- /dev/null +++ b/debian/patches/extra/0013-CVE-2018-6556-verify-netns-fd-in-lxc-user-nic.patch @@ -0,0 +1,115 @@ +From 590b215c4f5225cfb7fb58d9c56fabd5197bfdac Mon Sep 17 00:00:00 2001 +From: Christian Brauner +Date: Wed, 25 Jul 2018 19:56:54 +0200 +Subject: [PATCH] CVE 2018-6556: verify netns fd in lxc-user-nic +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +Signed-off-by: Christian Brauner +(cherry picked from commit c1cf54ebf251fdbad1e971679614e81649f1c032) +Signed-off-by: Fabian Grünbichler +--- + src/lxc/utils.h | 5 +++++ + src/lxc/cmd/lxc_user_nic.c | 35 ++++++++++++++++++++++++++++++++--- + src/lxc/utils.c | 12 ++++++++++++ + 3 files changed, 49 insertions(+), 3 deletions(-) + +diff --git a/src/lxc/utils.h b/src/lxc/utils.h +index ed486853..4dff26ae 100644 +--- a/src/lxc/utils.h ++++ b/src/lxc/utils.h +@@ -95,6 +95,10 @@ + #define CGROUP2_SUPER_MAGIC 0x63677270 + #endif + ++#ifndef NSFS_MAGIC ++#define NSFS_MAGIC 0x6e736673 ++#endif ++ + /* Useful macros */ + /* Maximum number for 64 bit integer is a string with 21 digits: 2^64 - 1 = 21 */ + #define LXC_NUMSTRLEN64 21 +@@ -580,6 +584,7 @@ extern void *must_realloc(void *orig, size_t sz); + /* __typeof__ should be safe to use with all compilers. */ + typedef __typeof__(((struct statfs *)NULL)->f_type) fs_type_magic; + extern bool has_fs_type(const char *path, fs_type_magic magic_val); ++extern bool fhas_fs_type(int fd, fs_type_magic magic_val); + extern bool is_fs_type(const struct statfs *fs, fs_type_magic magic_val); + extern bool lxc_nic_exists(char *nic); + extern int lxc_make_tmpfile(char *template, bool rm); +diff --git a/src/lxc/cmd/lxc_user_nic.c b/src/lxc/cmd/lxc_user_nic.c +index ec9cd97e..c5beb6c8 100644 +--- a/src/lxc/cmd/lxc_user_nic.c ++++ b/src/lxc/cmd/lxc_user_nic.c +@@ -1179,12 +1179,41 @@ int main(int argc, char *argv[]) + exit(EXIT_FAILURE); + } + } else if (request == LXC_USERNIC_DELETE) { +- netns_fd = open(args.pid, O_RDONLY); ++ char opath[LXC_PROC_PID_FD_LEN]; ++ ++ /* Open the path with O_PATH which will not trigger an actual ++ * open(). Don't report an errno to the caller to not leak ++ * information whether the path exists or not. ++ * When stracing setuid is stripped so this is not a concern ++ * either. ++ */ ++ netns_fd = open(args.pid, O_PATH | O_CLOEXEC); + if (netns_fd < 0) { +- usernic_error("Could not open \"%s\": %s\n", args.pid, +- strerror(errno)); ++ usernic_error("Failed to open \"%s\"\n", args.pid); ++ exit(EXIT_FAILURE); ++ } ++ ++ if (!fhas_fs_type(netns_fd, NSFS_MAGIC)) { ++ usernic_error("Path \"%s\" does not refer to a network namespace path\n", args.pid); ++ close(netns_fd); ++ exit(EXIT_FAILURE); ++ } ++ ++ ret = snprintf(opath, sizeof(opath), "/proc/self/fd/%d", netns_fd); ++ if (ret < 0 || (size_t)ret >= sizeof(opath)) { ++ close(netns_fd); ++ exit(EXIT_FAILURE); ++ } ++ ++ /* Now get an fd that we can use in setns() calls. */ ++ ret = open(opath, O_RDONLY | O_CLOEXEC); ++ if (ret < 0) { ++ usernic_error("Failed to open \"%s\": %s\n", args.pid, strerror(errno)); ++ close(netns_fd); + exit(EXIT_FAILURE); + } ++ close(netns_fd); ++ netns_fd = ret; + } + + if (!create_db_dir(LXC_USERNIC_DB)) { +diff --git a/src/lxc/utils.c b/src/lxc/utils.c +index 9771b900..e6f600f9 100644 +--- a/src/lxc/utils.c ++++ b/src/lxc/utils.c +@@ -2551,6 +2551,18 @@ bool has_fs_type(const char *path, fs_type_magic magic_val) + return has_type; + } + ++bool fhas_fs_type(int fd, fs_type_magic magic_val) ++{ ++ int ret; ++ struct statfs sb; ++ ++ ret = fstatfs(fd, &sb); ++ if (ret < 0) ++ return false; ++ ++ return is_fs_type(&sb, magic_val); ++} ++ + bool lxc_nic_exists(char *nic) + { + #define __LXC_SYS_CLASS_NET_LEN 15 + IFNAMSIZ + 1 +-- +2.18.0 + diff --git a/debian/patches/series b/debian/patches/series index 348b685..9446a34 100644 --- a/debian/patches/series +++ b/debian/patches/series @@ -18,3 +18,4 @@ extra/0009-apparmor-update-current-profiles.patch extra/0010-apparmor-profile-generation.patch extra/0011-apparmor-allow-start-container-to-change-to-lxc.patch extra/0012-tests-add-test-for-generated-apparmor-profiles.patch +extra/0013-CVE-2018-6556-verify-netns-fd-in-lxc-user-nic.patch -- 2.39.2