apparmor: allow ptrace checks to be finer grained than just capability

Signed-off-by: John Johansen <john.johansen@canonical.com>

diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index d24100f..d1a6ce4 100644 (file)
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -2086,6 +2086,11 @@ static struct aa_sfs_entry aa_sfs_entry_file[] = {
        { }
 };
 
+static struct aa_sfs_entry aa_sfs_entry_ptrace[] = {
+       AA_SFS_FILE_STRING("mask", "read trace"),
+       { }
+};
+
 static struct aa_sfs_entry aa_sfs_entry_domain[] = {
        AA_SFS_FILE_BOOLEAN("change_hat",       1),
        AA_SFS_FILE_BOOLEAN("change_hatv",      1),
@@ -2125,6 +2130,7 @@ static struct aa_sfs_entry aa_sfs_entry_features[] = {
        AA_SFS_FILE_U64("capability",           VFS_CAP_FLAGS_MASK),
        AA_SFS_DIR("rlimit",                    aa_sfs_entry_rlimit),
        AA_SFS_DIR("caps",                      aa_sfs_entry_caps),
+       AA_SFS_DIR("ptrace",                    aa_sfs_entry_ptrace),
        AA_SFS_DIR("query",                     aa_sfs_entry_query),
        { }
 };

diff --git a/security/apparmor/include/ipc.h b/security/apparmor/include/ipc.h
index fb3e751..656fdb8 100644 (file)
--- a/security/apparmor/include/ipc.h
+++ b/security/apparmor/include/ipc.h
@@ -21,6 +21,12 @@ struct aa_profile;
 
 #define AA_PTRACE_TRACE                MAY_WRITE
 #define AA_PTRACE_READ         MAY_READ
+#define AA_MAY_BE_TRACED       AA_MAY_APPEND
+#define AA_MAY_BE_READ         AA_MAY_CREATE
+#define PTRACE_PERM_SHIFT      2
+
+#define AA_PTRACE_PERM_MASK (AA_PTRACE_READ | AA_PTRACE_TRACE | \
+                            AA_MAY_BE_READ | AA_MAY_BE_TRACED)
 
 int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
                  u32 request);

diff --git a/security/apparmor/ipc.c b/security/apparmor/ipc.c
index f816493..11e66b5 100644 (file)
--- a/security/apparmor/ipc.c
+++ b/security/apparmor/ipc.c
@@ -21,20 +21,76 @@
 #include "include/policy.h"
 #include "include/ipc.h"
 
+/**
+ * audit_ptrace_mask - convert mask to permission string
+ * @buffer: buffer to write string to (NOT NULL)
+ * @mask: permission mask to convert
+ */
+static void audit_ptrace_mask(struct audit_buffer *ab, u32 mask)
+{
+       switch (mask) {
+       case MAY_READ:
+               audit_log_string(ab, "read");
+               break;
+       case MAY_WRITE:
+               audit_log_string(ab, "trace");
+               break;
+       case AA_MAY_BE_READ:
+               audit_log_string(ab, "readby");
+               break;
+       case AA_MAY_BE_TRACED:
+               audit_log_string(ab, "tracedby");
+               break;
+       }
+}
+
 /* call back to audit ptrace fields */
 static void audit_ptrace_cb(struct audit_buffer *ab, void *va)
 {
        struct common_audit_data *sa = va;
 
+       if (aad(sa)->request & AA_PTRACE_PERM_MASK) {
+               audit_log_format(ab, " requested_mask=");
+               audit_ptrace_mask(ab, aad(sa)->request);
+
+               if (aad(sa)->denied & AA_PTRACE_PERM_MASK) {
+                       audit_log_format(ab, " denied_mask=");
+                       audit_ptrace_mask(ab, aad(sa)->denied);
+               }
+       }
        audit_log_format(ab, " peer=");
        aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
                        FLAGS_NONE, GFP_ATOMIC);
 }
 
+/* TODO: conditionals */
+static int profile_ptrace_perm(struct aa_profile *profile,
+                              struct aa_profile *peer, u32 request,
+                              struct common_audit_data *sa)
+{
+       struct aa_perms perms = { };
+
+       /* need because of peer in cross check */
+       if (profile_unconfined(profile) ||
+           !PROFILE_MEDIATES(profile, AA_CLASS_PTRACE))
+               return 0;
+
+       aad(sa)->peer = &peer->label;
+       aa_profile_match_label(profile, &peer->label, AA_CLASS_PTRACE, request,
+                              &perms);
+       aa_apply_modes_to_perms(profile, &perms);
+       return aa_check_perms(profile, &perms, request, sa, audit_ptrace_cb);
+}
+
 static int cross_ptrace_perm(struct aa_profile *tracer,
                             struct aa_profile *tracee, u32 request,
                             struct common_audit_data *sa)
 {
+       if (PROFILE_MEDIATES(tracer, AA_CLASS_PTRACE))
+               return xcheck(profile_ptrace_perm(tracer, tracee, request, sa),
+                             profile_ptrace_perm(tracee, tracer,
+                                                 request << PTRACE_PERM_SHIFT,
+                                                 sa));
        /* policy uses the old style capability check for ptrace */
        if (profile_unconfined(tracer) || tracer == tracee)
                return 0;