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124 lines
6.0 KiB
124 lines
6.0 KiB
From 42ed3377b5817f2c1f84e1bdca301ea51ecc3299 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
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Date: Thu, 20 Sep 2018 14:19:41 +0200
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Subject: [PATCH] seccomp: tighten checking of seccomp filter creation
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In seccomp code, the code is changed to propagate errors which are about
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anything other than unknown/unimplemented syscalls. I *think* such errors
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should not happen in normal usage, but so far we would summarilly ignore all
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errors, so that part is uncertain. If it turns out that other errors occur and
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should be ignored, this should be added later.
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In nspawn, we would count the number of added filters, but didn't use this for
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anything. Drop that part.
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The comments suggested that seccomp_add_syscall_filter_item() returned negative
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if the syscall is unknown, but this wasn't true: it returns 0.
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The error at this point can only be if the syscall was known but couldn't be
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added. If the error comes from our internal whitelist in nspawn, treat this as
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error, because it means that our internal table is wrong. If the error comes
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from user arguments, warn and ignore. (If some syscall is not known at current
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architecture, it is still silently ignored.)
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(cherry picked from commit 7e86bd73a47f2b8dd3d9a743e69fb0117f450ad8)
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Related: #2040247
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---
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src/nspawn/nspawn-seccomp.c | 14 +++++---------
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src/shared/seccomp-util.c | 26 ++++++++++++++++----------
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2 files changed, 21 insertions(+), 19 deletions(-)
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diff --git a/src/nspawn/nspawn-seccomp.c b/src/nspawn/nspawn-seccomp.c
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index fba22644da..17abfcec26 100644
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--- a/src/nspawn/nspawn-seccomp.c
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+++ b/src/nspawn/nspawn-seccomp.c
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@@ -140,7 +140,7 @@ static int seccomp_add_default_syscall_filter(
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*/
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};
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- int r, c = 0;
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+ int r;
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size_t i;
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char **p;
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@@ -150,21 +150,17 @@ static int seccomp_add_default_syscall_filter(
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r = seccomp_add_syscall_filter_item(ctx, whitelist[i].name, SCMP_ACT_ALLOW, syscall_blacklist, false);
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if (r < 0)
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- /* If the system call is not known on this architecture, then that's fine, let's ignore it */
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- log_debug_errno(r, "Failed to add rule for system call %s on %s, ignoring: %m", whitelist[i].name, seccomp_arch_to_string(arch));
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- else
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- c++;
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+ return log_error_errno(r, "Failed to add syscall filter item %s: %m", whitelist[i].name);
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}
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STRV_FOREACH(p, syscall_whitelist) {
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r = seccomp_add_syscall_filter_item(ctx, *p, SCMP_ACT_ALLOW, syscall_blacklist, false);
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if (r < 0)
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- log_debug_errno(r, "Failed to add rule for system call %s on %s, ignoring: %m", *p, seccomp_arch_to_string(arch));
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- else
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- c++;
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+ log_warning_errno(r, "Failed to add rule for system call %s on %s, ignoring: %m",
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+ *p, seccomp_arch_to_string(arch));
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}
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- return c;
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+ return 0;
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}
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int setup_seccomp(uint64_t cap_list_retain, char **syscall_whitelist, char **syscall_blacklist) {
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diff --git a/src/shared/seccomp-util.c b/src/shared/seccomp-util.c
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index 4d2ba31d47..710a734715 100644
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--- a/src/shared/seccomp-util.c
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+++ b/src/shared/seccomp-util.c
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@@ -907,9 +907,13 @@ int seccomp_add_syscall_filter_item(scmp_filter_ctx *seccomp, const char *name,
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r = seccomp_rule_add_exact(seccomp, action, id, 0);
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if (r < 0) {
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/* If the system call is not known on this architecture, then that's fine, let's ignore it */
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- if (log_missing)
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- log_debug_errno(r, "Failed to add rule for system call %s() / %d, ignoring: %m",
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- name, id);
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+ bool ignore = r == -EDOM;
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+
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+ if (!ignore || log_missing)
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+ log_debug_errno(r, "Failed to add rule for system call %s() / %d%s: %m",
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+ name, id, ignore ? ", ignoring" : "");
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+ if (!ignore)
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+ return r;
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}
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return 0;
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@@ -957,10 +961,8 @@ int seccomp_load_syscall_filter_set(uint32_t default_action, const SyscallFilter
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return r;
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r = seccomp_add_syscall_filter_set(seccomp, set, action, NULL, log_missing);
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- if (r < 0) {
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- log_debug_errno(r, "Failed to add filter set, ignoring: %m");
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- continue;
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- }
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+ if (r < 0)
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+ return log_debug_errno(r, "Failed to add filter set: %m");
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r = seccomp_load(seccomp);
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if (IN_SET(r, -EPERM, -EACCES))
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@@ -1005,11 +1007,15 @@ int seccomp_load_syscall_filter_set_raw(uint32_t default_action, Hashmap* set, u
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if (r < 0) {
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/* If the system call is not known on this architecture, then that's fine, let's ignore it */
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_cleanup_free_ char *n = NULL;
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+ bool ignore;
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n = seccomp_syscall_resolve_num_arch(SCMP_ARCH_NATIVE, id);
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- if (log_missing)
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- log_debug_errno(r, "Failed to add rule for system call %s() / %d, ignoring: %m",
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- strna(n), id);
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+ ignore = r == -EDOM;
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+ if (!ignore || log_missing)
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+ log_debug_errno(r, "Failed to add rule for system call %s() / %d%s: %m",
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+ strna(n), id, ignore ? ", ignoring" : "");
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+ if (!ignore)
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+ return r;
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}
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}
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