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authorJohn Johansen <john.johansen@canonical.com>2017-05-26 18:35:29 -0700
committerJohn Johansen <john.johansen@canonical.com>2017-06-10 17:11:30 -0700
commit4f3b3f2d79a42e5094f55eca4f29d8f60f1190bd (patch)
treed8422ba9a6d8b6b77c678d96f234e06bee3a151a /security
parent2d679f3cb0eaa6afa0dc97fe6ad3b797e1c1899a (diff)
downloadlinux-4f3b3f2d79a42e5094f55eca4f29d8f60f1190bd.tar.bz2
apparmor: add profile permission query ability
Allow userspace to query a profile about permissions, through the transaction interface that is already used to allow userspace to query about key,value data. Signed-off-by: John Johansen <john.johansen@canonical.com>
Diffstat (limited to 'security')
-rw-r--r--security/apparmor/apparmorfs.c103
1 files changed, 102 insertions, 1 deletions
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index e553de58f801..105a1da57b8f 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -595,6 +595,40 @@ static const struct file_operations aa_fs_ns_revision_fops = {
.release = ns_revision_release,
};
+static void profile_query_cb(struct aa_profile *profile, struct aa_perms *perms,
+ const char *match_str, size_t match_len)
+{
+ struct aa_perms tmp;
+ struct aa_dfa *dfa;
+ unsigned int state = 0;
+
+ if (unconfined(profile))
+ return;
+ if (profile->file.dfa && *match_str == AA_CLASS_FILE) {
+ dfa = profile->file.dfa;
+ state = aa_dfa_match_len(dfa, profile->file.start,
+ match_str + 1, match_len - 1);
+ tmp = nullperms;
+ if (state) {
+ struct path_cond cond = { };
+
+ tmp = aa_compute_fperms(dfa, state, &cond);
+ }
+ } else if (profile->policy.dfa) {
+ if (!PROFILE_MEDIATES_SAFE(profile, *match_str))
+ return; /* no change to current perms */
+ dfa = profile->policy.dfa;
+ state = aa_dfa_match_len(dfa, profile->policy.start[0],
+ match_str, match_len);
+ if (state)
+ aa_compute_perms(dfa, state, &tmp);
+ else
+ tmp = nullperms;
+ }
+ aa_apply_modes_to_perms(profile, &tmp);
+}
+
+
/**
* query_data - queries a policy and writes its data to buf
* @buf: the resulting data is stored here (NOT NULL)
@@ -673,6 +707,64 @@ static ssize_t query_data(char *buf, size_t buf_len,
return out - buf;
}
+/**
+ * query_label - queries a label and writes permissions to buf
+ * @buf: the resulting permissions string is stored here (NOT NULL)
+ * @buf_len: size of buf
+ * @query: binary query string to match against the dfa
+ * @query_len: size of query
+ * @view_only: only compute for querier's view
+ *
+ * The buffers pointed to by buf and query may overlap. The query buffer is
+ * parsed before buf is written to.
+ *
+ * The query should look like "LABEL_NAME\0DFA_STRING" where LABEL_NAME is
+ * the name of the label, in the current namespace, that is to be queried and
+ * DFA_STRING is a binary string to match against the label(s)'s DFA.
+ *
+ * LABEL_NAME must be NUL terminated. DFA_STRING may contain NUL characters
+ * but must *not* be NUL terminated.
+ *
+ * Returns: number of characters written to buf or -errno on failure
+ */
+static ssize_t query_label(char *buf, size_t buf_len,
+ char *query, size_t query_len, bool view_only)
+{
+ struct aa_profile *profile, *curr;
+ char *label_name, *match_str;
+ size_t label_name_len, match_len;
+ struct aa_perms perms;
+
+ if (!query_len)
+ return -EINVAL;
+
+ label_name = query;
+ label_name_len = strnlen(query, query_len);
+ if (!label_name_len || label_name_len == query_len)
+ return -EINVAL;
+
+ /**
+ * The extra byte is to account for the null byte between the
+ * profile name and dfa string. profile_name_len is greater
+ * than zero and less than query_len, so a byte can be safely
+ * added or subtracted.
+ */
+ match_str = label_name + label_name_len + 1;
+ match_len = query_len - label_name_len - 1;
+
+ curr = aa_current_profile();
+ profile = aa_fqlookupn_profile(curr, label_name, label_name_len);
+ if (!profile)
+ return -ENOENT;
+
+ perms = allperms;
+ profile_query_cb(profile, &perms, match_str, match_len);
+
+ return scnprintf(buf, buf_len,
+ "allow 0x%08x\ndeny 0x%08x\naudit 0x%08x\nquiet 0x%08x\n",
+ perms.allow, perms.deny, perms.audit, perms.quiet);
+}
+
/*
* Transaction based IO.
* The file expects a write which triggers the transaction, and then
@@ -773,6 +865,9 @@ static int multi_transaction_release(struct inode *inode, struct file *file)
return 0;
}
+#define QUERY_CMD_PROFILE "profile\0"
+#define QUERY_CMD_PROFILE_LEN 8
+
#define QUERY_CMD_DATA "data\0"
#define QUERY_CMD_DATA_LEN 5
@@ -810,7 +905,12 @@ static ssize_t aa_write_access(struct file *file, const char __user *ubuf,
if (IS_ERR(t))
return PTR_ERR(t);
- if (count > QUERY_CMD_DATA_LEN &&
+ if (count > QUERY_CMD_PROFILE_LEN &&
+ !memcmp(t->data, QUERY_CMD_PROFILE, QUERY_CMD_PROFILE_LEN)) {
+ len = query_label(t->data, MULTI_TRANSACTION_LIMIT,
+ t->data + QUERY_CMD_PROFILE_LEN,
+ count - QUERY_CMD_PROFILE_LEN, true);
+ } else if (count > QUERY_CMD_DATA_LEN &&
!memcmp(t->data, QUERY_CMD_DATA, QUERY_CMD_DATA_LEN)) {
len = query_data(t->data, MULTI_TRANSACTION_LIMIT,
t->data + QUERY_CMD_DATA_LEN,
@@ -1952,6 +2052,7 @@ static struct aa_sfs_entry aa_sfs_entry_policy[] = {
};
static struct aa_sfs_entry aa_sfs_entry_query_label[] = {
+ AA_SFS_FILE_STRING("perms", "allow deny audit quiet"),
AA_SFS_FILE_BOOLEAN("data", 1),
AA_SFS_FILE_BOOLEAN("multi_transaction", 1),
{ }