[systemd-commits] src/nspawn

[Zbigniew Jędrzejewski-Szmek]

 src/nspawn/nspawn.c |   44 +++++++++++++++++---------------------------
 1 file changed, 17 insertions(+), 27 deletions(-)

New commits:
commit 9a71b1122c6e49dd9227f82b2f53837c7ea13019
Author: Jay Faulkner <jay at jvf.cc>
Date:   Fri Feb 20 21:59:47 2015 +0000

    nspawn: Map all seccomp filters to capabilities
    
    This change makes it so all seccomp filters are mapped
    to the appropriate capability and are only added if that
    capability was not requested when running the container.
    
    This unbreaks the remaining use cases broken by the
    addition of seccomp filters without respecting requested
    capabilities.
    
    Co-Authored-By: Clif Houck <me at clifhouck.com>
    
    [zj: - adapt to our coding style, make struct anonymous]

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 8ce5fbe..8833704 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -2567,19 +2567,19 @@ static int setup_ipvlan(pid_t pid) {
 static int setup_seccomp(void) {
 
 #ifdef HAVE_SECCOMP
-        static const int blacklist[] = {
-                SCMP_SYS(kexec_load),
-                SCMP_SYS(open_by_handle_at),
-                SCMP_SYS(iopl),
-                SCMP_SYS(ioperm),
-                SCMP_SYS(swapon),
-                SCMP_SYS(swapoff),
-        };
-
-        static const int kmod_blacklist[] = {
-                SCMP_SYS(init_module),
-                SCMP_SYS(finit_module),
-                SCMP_SYS(delete_module),
+        static const struct {
+                uint64_t capability;
+                int syscall_num;
+        } blacklist[] = {
+                { CAP_SYS_RAWIO,  SCMP_SYS(iopl)},
+                { CAP_SYS_RAWIO,  SCMP_SYS(ioperm)},
+                { CAP_SYS_BOOT,   SCMP_SYS(kexec_load)},
+                { CAP_SYS_ADMIN,  SCMP_SYS(swapon)},
+                { CAP_SYS_ADMIN,  SCMP_SYS(swapoff)},
+                { CAP_SYS_ADMIN,  SCMP_SYS(open_by_handle_at)},
+                { CAP_SYS_MODULE, SCMP_SYS(init_module)},
+                { CAP_SYS_MODULE, SCMP_SYS(finit_module)},
+                { CAP_SYS_MODULE, SCMP_SYS(delete_module)},
         };
 
         scmp_filter_ctx seccomp;
@@ -2597,7 +2597,10 @@ static int setup_seccomp(void) {
         }
 
         for (i = 0; i < ELEMENTSOF(blacklist); i++) {
-                r = seccomp_rule_add(seccomp, SCMP_ACT_ERRNO(EPERM), blacklist[i], 0);
+                if (arg_retain & (1ULL << blacklist[i].capability))
+                        continue;
+
+                r = seccomp_rule_add(seccomp, SCMP_ACT_ERRNO(EPERM), blacklist[i].syscall_num, 0);
                 if (r == -EFAULT)
                         continue; /* unknown syscall */
                 if (r < 0) {
@@ -2606,19 +2609,6 @@ static int setup_seccomp(void) {
                 }
         }
 
-        /* If the CAP_SYS_MODULE capability is not requested then
-         * we'll block the kmod syscalls too */
-        if (!(arg_retain & (1ULL << CAP_SYS_MODULE))) {
-                for (i = 0; i < ELEMENTSOF(kmod_blacklist); i++) {
-                        r = seccomp_rule_add(seccomp, SCMP_ACT_ERRNO(EPERM), kmod_blacklist[i], 0);
-                        if (r == -EFAULT)
-                                continue; /* unknown syscall */
-                        if (r < 0) {
-                                log_error_errno(r, "Failed to block syscall: %m");
-                                goto finish;
-                        }
-                }
-        }
 
         /*
            Audit is broken in containers, much of the userspace audit