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>
This commit is contained in:
John Johansen 2017-05-26 18:35:29 -07:00
parent 2d679f3cb0
commit 4f3b3f2d79
1 changed files with 102 additions and 1 deletions

View File

@ -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),
{ }