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authorJohn Johansen <john.johansen@canonical.com>2017-07-18 22:56:22 -0700
committerJohn Johansen <john.johansen@canonical.com>2017-09-22 13:00:57 -0700
commitcd1dbf76b23d5ab2cba5e657fe20b1e236a408cc (patch)
tree20a0180f2c6620b46a738946d943d00752eb4844 /security/apparmor/ipc.c
parentc5561700c9cb951ec3a33a0914c840423b09d7c9 (diff)
downloadlinux-cd1dbf76b23d5ab2cba5e657fe20b1e236a408cc.tar.bz2
apparmor: add the ability to mediate signals
Add signal mediation where the signal can be mediated based on the signal, direction, or the label or the peer/target. The signal perms are verified on a cross check to ensure policy consistency in the case of incremental policy load/replacement. The optimization of skipping the cross check when policy is guaranteed to be consistent (single compile unit) remains to be done. policy rules have the form of SIGNAL_RULE = [ QUALIFIERS ] 'signal' [ SIGNAL ACCESS PERMISSIONS ] [ SIGNAL SET ] [ SIGNAL PEER ] SIGNAL ACCESS PERMISSIONS = SIGNAL ACCESS | SIGNAL ACCESS LIST SIGNAL ACCESS LIST = '(' Comma or space separated list of SIGNAL ACCESS ')' SIGNAL ACCESS = ( 'r' | 'w' | 'rw' | 'read' | 'write' | 'send' | 'receive' ) SIGNAL SET = 'set' '=' '(' SIGNAL LIST ')' SIGNAL LIST = Comma or space separated list of SIGNALS SIGNALS = ( 'hup' | 'int' | 'quit' | 'ill' | 'trap' | 'abrt' | 'bus' | 'fpe' | 'kill' | 'usr1' | 'segv' | 'usr2' | 'pipe' | 'alrm' | 'term' | 'stkflt' | 'chld' | 'cont' | 'stop' | 'stp' | 'ttin' | 'ttou' | 'urg' | 'xcpu' | 'xfsz' | 'vtalrm' | 'prof' | 'winch' | 'io' | 'pwr' | 'sys' | 'emt' | 'exists' | 'rtmin+0' ... 'rtmin+32' ) SIGNAL PEER = 'peer' '=' AARE eg. signal, # allow all signals signal send set=(hup, kill) peer=foo, Signed-off-by: John Johansen <john.johansen@canonical.com> Acked-by: Seth Arnold <seth.arnold@canonical.com>
Diffstat (limited to 'security/apparmor/ipc.c')
-rw-r--r--security/apparmor/ipc.c99
1 files changed, 99 insertions, 0 deletions
diff --git a/security/apparmor/ipc.c b/security/apparmor/ipc.c
index 11e66b5bbc42..66fb9ede9447 100644
--- a/security/apparmor/ipc.c
+++ b/security/apparmor/ipc.c
@@ -20,6 +20,7 @@
#include "include/context.h"
#include "include/policy.h"
#include "include/ipc.h"
+#include "include/sig_names.h"
/**
* audit_ptrace_mask - convert mask to permission string
@@ -121,3 +122,101 @@ int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
}
+static inline int map_signal_num(int sig)
+{
+ if (sig > SIGRTMAX)
+ return SIGUNKNOWN;
+ else if (sig >= SIGRTMIN)
+ return sig - SIGRTMIN + 128; /* rt sigs mapped to 128 */
+ else if (sig <= MAXMAPPED_SIG)
+ return sig_map[sig];
+ return SIGUNKNOWN;
+}
+
+/**
+ * audit_file_mask - convert mask to permission string
+ * @buffer: buffer to write string to (NOT NULL)
+ * @mask: permission mask to convert
+ */
+static void audit_signal_mask(struct audit_buffer *ab, u32 mask)
+{
+ if (mask & MAY_READ)
+ audit_log_string(ab, "receive");
+ if (mask & MAY_WRITE)
+ audit_log_string(ab, "send");
+}
+
+/**
+ * audit_cb - call back for signal specific audit fields
+ * @ab: audit_buffer (NOT NULL)
+ * @va: audit struct to audit values of (NOT NULL)
+ */
+static void audit_signal_cb(struct audit_buffer *ab, void *va)
+{
+ struct common_audit_data *sa = va;
+
+ if (aad(sa)->request & AA_SIGNAL_PERM_MASK) {
+ audit_log_format(ab, " requested_mask=");
+ audit_signal_mask(ab, aad(sa)->request);
+ if (aad(sa)->denied & AA_SIGNAL_PERM_MASK) {
+ audit_log_format(ab, " denied_mask=");
+ audit_signal_mask(ab, aad(sa)->denied);
+ }
+ }
+ if (aad(sa)->signal <= MAXMAPPED_SIG)
+ audit_log_format(ab, " signal=%s", sig_names[aad(sa)->signal]);
+ else
+ audit_log_format(ab, " signal=rtmin+%d",
+ aad(sa)->signal - 128);
+ audit_log_format(ab, " peer=");
+ aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
+ FLAGS_NONE, GFP_ATOMIC);
+}
+
+/* TODO: update to handle compound name&name2, conditionals */
+static void profile_match_signal(struct aa_profile *profile, const char *label,
+ int signal, struct aa_perms *perms)
+{
+ unsigned int state;
+
+ /* TODO: secondary cache check <profile, profile, perm> */
+ state = aa_dfa_next(profile->policy.dfa,
+ profile->policy.start[AA_CLASS_SIGNAL],
+ signal);
+ state = aa_dfa_match(profile->policy.dfa, state, label);
+ aa_compute_perms(profile->policy.dfa, state, perms);
+}
+
+static int profile_signal_perm(struct aa_profile *profile,
+ struct aa_profile *peer, u32 request,
+ struct common_audit_data *sa)
+{
+ struct aa_perms perms;
+
+ if (profile_unconfined(profile) ||
+ !PROFILE_MEDIATES(profile, AA_CLASS_SIGNAL))
+ return 0;
+
+ aad(sa)->peer = &peer->label;
+ profile_match_signal(profile, peer->base.hname, aad(sa)->signal,
+ &perms);
+ aa_apply_modes_to_perms(profile, &perms);
+ return aa_check_perms(profile, &perms, request, sa, audit_signal_cb);
+}
+
+static int aa_signal_cross_perm(struct aa_profile *sender,
+ struct aa_profile *target,
+ struct common_audit_data *sa)
+{
+ return xcheck(profile_signal_perm(sender, target, MAY_WRITE, sa),
+ profile_signal_perm(target, sender, MAY_READ, sa));
+}
+
+int aa_may_signal(struct aa_label *sender, struct aa_label *target, int sig)
+{
+ DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SIGNAL);
+
+ aad(&sa)->signal = map_signal_num(sig);
+ return xcheck_labels_profiles(sender, target, aa_signal_cross_perm,
+ &sa);
+}