This patch, for debugging only, introduces a silly admin-controlled
'policy version' for smack. By default the version is 1. An
admin (with CAP_MAC_ADMIN) can change it by echoing a new value
into /smack/version.
It then defines security_checkpoint_header() to add this 'policy
version' into the checkpoint header, and defines security_may_restart()
to refuse restart if both:
1. the caller asked for RESTART_KEEP_LSM
and
2. the checkpointed version was different from the current.
This of course is easy enough to test by doing
echo 1 > /smack/version
ckpt > out
mktree < out
succeed
mktree -k < out
succeed
echo 2 > /smack/version
mktree < out
succeed
mktree -k < out
fail
Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
---
security/smack/smack_lsm.c | 46 +++++++++++++++++++++++++++
security/smack/smackfs.c | 75 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 121 insertions(+), 0 deletions(-)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 279fdce..f0d4a08 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -27,6 +27,7 @@
#include <linux/udp.h>
#include <linux/mutex.h>
#include <linux/pipe_fs_i.h>
+#include <linux/checkpoint.h>
#include <net/netlabel.h>
#include <net/cipso_ipv4.h>
#include <linux/audit.h>
@@ -3111,6 +3112,47 @@ static void smack_release_secctx(char *secdata, u32 seclen)
{
}
+#ifdef CONFIG_CHECKPOINT
+extern int smack_version;
+
+static int smack_may_restart(struct ckpt_ctx *ctx)
+{
+ struct ckpt_hdr *h;
+ char *smackv;
+ int v = 0, slen, ret;
+
+ h = ckpt_read_buf_type(ctx, CKPT_LSM_INFO_LEN, CKPT_HDR_LSM_INFO);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ if (strcmp(ctx->lsm_name, "smack") != 0)
+ return 0;
+
+ smackv = (char *) (h + 1);
+ slen = h->len - sizeof(*h);
+ if (smackv[slen-1] != '\0')
+ smackv[slen-1] = '\0';
+ ret = sscanf(smackv, "%d", &v);
+ ckpt_hdr_put(ctx, h);
+ if (!(ctx->uflags & RESTART_KEEP_LSM))
+ return 0;
+ if (ret != 1 || v != smack_version) {
+ ckpt_debug("Smack version at checkpoint was %d, now is %d\n",
+ v, smack_version);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static int smack_checkpoint_header(struct ckpt_ctx *ctx)
+{
+ char smackv[10];
+ sprintf(smackv, "%d", smack_version);
+ return ckpt_write_obj_type(ctx, smackv, strlen(smackv)+1,
+ CKPT_HDR_LSM_INFO);
+}
+#endif
+
struct security_operations smack_ops = {
.name = "smack",
@@ -3245,6 +3287,10 @@ struct security_operations smack_ops = {
.secid_to_secctx = smack_secid_to_secctx,
.secctx_to_secid = smack_secctx_to_secid,
.release_secctx = smack_release_secctx,
+#ifdef CONFIG_CHECKPOINT
+ .may_restart = smack_may_restart,
+ .checkpoint_header = smack_checkpoint_header,
+#endif
};
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index f83a809..7b20ad9 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -42,6 +42,7 @@ enum smk_inos {
SMK_NETLBLADDR = 8, /* single label hosts */
SMK_ONLYCAP = 9, /* the only "capable" label */
SMK_LOGGING = 10, /* logging */
+ SMK_VERSION = 11, /* logging */
};
/*
@@ -51,6 +52,7 @@ static DEFINE_MUTEX(smack_list_lock);
static DEFINE_MUTEX(smack_cipso_lock);
static DEFINE_MUTEX(smack_ambient_lock);
static DEFINE_MUTEX(smk_netlbladdr_lock);
+static DEFINE_MUTEX(smack_version_lock);
/*
* This is the "ambient" label for network traffic.
@@ -60,6 +62,11 @@ static DEFINE_MUTEX(smk_netlbladdr_lock);
char *smack_net_ambient = smack_known_floor.smk_known;
/*
+ * this is the policy version, a simple integer
+ */
+int smack_version = 1;
+
+/*
* This is the level in a CIPSO header that indicates a
* smack label is contained directly in the category set.
* It can be reset via smackfs/direct
@@ -1255,6 +1262,72 @@ static const struct file_operations smk_logging_ops = {
.read = smk_read_logging,
.write = smk_write_logging,
};
+
+#define SMK_VERSIONLEN 12
+/**
+ * smk_read_version - read() for /smack/version
+ * @filp: file pointer, not actually used
+ * @buf: where to put the result
+ * @cn: maximum to send along
+ * @ppos: where to start
+ *
+ * Returns number of bytes read or error code, as appropriate
+ */
+static ssize_t smk_read_version(struct file *filp, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ char temp[SMK_VERSIONLEN];
+
+ if (*ppos != 0)
+ return 0;
+
+ mutex_lock(&smack_version_lock);
+ sprintf(temp, "%d\n", smack_version);
+ mutex_unlock(&smack_version_lock);
+
+ return simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
+}
+
+/**
+ * smk_write_version - write() for /smack/version
+ * @file: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t smk_write_version(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ char in[SMK_VERSIONLEN];
+ int tmp, ret;
+
+ if (!capable(CAP_MAC_ADMIN))
+ return -EPERM;
+
+ if (count >= SMK_VERSIONLEN)
+ return -EINVAL;
+
+ if (copy_from_user(in, buf, count) != 0)
+ return -EFAULT;
+
+ in[count-1] = '\0';
+ ret = sscanf(in, "%d", &tmp);
+ if (ret != 1)
+ return -EINVAL;
+ mutex_lock(&smack_version_lock);
+ smack_version = tmp;
+ mutex_unlock(&smack_version_lock);
+
+ return count;
+}
+
+static const struct file_operations smk_version_ops = {
+ .read = smk_read_version,
+ .write = smk_write_version,
+};
+
/**
* smk_fill_super - fill the /smackfs superblock
* @sb: the empty superblock
@@ -1287,6 +1360,8 @@ static int smk_fill_super(struct super_block *sb, void *data, int silent)
{"onlycap", &smk_onlycap_ops, S_IRUGO|S_IWUSR},
[SMK_LOGGING] =
{"logging", &smk_logging_ops, S_IRUGO|S_IWUSR},
+ [SMK_VERSION] =
+ {"version", &smk_version_ops, S_IRUGO|S_IWUSR},
/* last one */ {""}
};
--
1.6.1
--
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