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Commit 4f3b3f2d authored by John Johansen's avatar John Johansen
Browse files

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: default avatarJohn Johansen <john.johansen@canonical.com>
parent 2d679f3c

security/apparmor/apparmorfs.c

+102 −1
Original line number Diff line number Diff line
@@ -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),

	{ }