Commit 0e6ebf87 authored by Thorsten Blum's avatar Thorsten Blum Committed by Paul Moore
Browse files

device_cgroup: Refactor devcgroup_seq_show to use seq_put* helpers 



Replace set_access(), set_majmin(), and type_to_char() with new helpers
seq_putaccess(), seq_puttype(), and seq_putversion() that write directly
to 'seq_file'.

Simplify devcgroup_seq_show() by hard-coding "a *:* rwm", and use the
new seq_put* helper functions to list the exceptions otherwise.

This allows us to remove the intermediate string buffers while
maintaining the same functionality, including wildcard handling.

Signed-off-by: default avatarThorsten Blum <thorsten.blum@linux.dev>
Acked-by: default avatarSerge Hallyn <serge@hallyn.com>
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent dfa024bc

security/device_cgroup.c

+25 −31
Original line number Diff line number Diff line
@@ -244,45 +244,40 @@ static void devcgroup_css_free(struct cgroup_subsys_state *css) 
#define DEVCG_DENY 2

#define DEVCG_LIST 3



#define MAJMINLEN 13

#define ACCLEN 4



static void set_access(char *acc, short access)

static void seq_putaccess(struct seq_file *m, short access)

{

	int idx = 0;

	memset(acc, 0, ACCLEN);

	if (access & DEVCG_ACC_READ)

		acc[idx++] = 'r';

		seq_putc(m, 'r');

	if (access & DEVCG_ACC_WRITE)

		acc[idx++] = 'w';

		seq_putc(m, 'w');

	if (access & DEVCG_ACC_MKNOD)

		acc[idx++] = 'm';

		seq_putc(m, 'm');

}



static char type_to_char(short type)

static void seq_puttype(struct seq_file *m, short type)

{

	if (type == DEVCG_DEV_ALL)

		return 'a';

	if (type == DEVCG_DEV_CHAR)

		return 'c';

	if (type == DEVCG_DEV_BLOCK)

		return 'b';

	return 'X';

		seq_putc(m, 'a');

	else if (type == DEVCG_DEV_CHAR)

		seq_putc(m, 'c');

	else if (type == DEVCG_DEV_BLOCK)

		seq_putc(m, 'b');

	else

		seq_putc(m, 'X');

}



static void set_majmin(char *str, unsigned m)

static void seq_putversion(struct seq_file *m, unsigned int version)

{

	if (m == ~0)

		strcpy(str, "*");

	if (version == ~0)

		seq_putc(m, '*');

	else

		sprintf(str, "%u", m);

		seq_printf(m, "%u", version);

}



static int devcgroup_seq_show(struct seq_file *m, void *v)

{

	struct dev_cgroup *devcgroup = css_to_devcgroup(seq_css(m));

	struct dev_exception_item *ex;

	char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN];



	rcu_read_lock();

	/*
@@ -292,18 +287,17 @@ static int devcgroup_seq_show(struct seq_file *m, void *v) 
	 * This way, the file remains as a "whitelist of devices"

	 */

	if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) {

		set_access(acc, DEVCG_ACC_MASK);

		set_majmin(maj, ~0);

		set_majmin(min, ~0);

		seq_printf(m, "%c %s:%s %s\n", type_to_char(DEVCG_DEV_ALL),

			   maj, min, acc);

		seq_puts(m, "a *:* rwm\n");

	} else {

		list_for_each_entry_rcu(ex, &devcgroup->exceptions, list) {

			set_access(acc, ex->access);

			set_majmin(maj, ex->major);

			set_majmin(min, ex->minor);

			seq_printf(m, "%c %s:%s %s\n", type_to_char(ex->type),

				   maj, min, acc);

			seq_puttype(m, ex->type);

			seq_putc(m, ' ');

			seq_putversion(m, ex->major);

			seq_putc(m, ':');

			seq_putversion(m, ex->minor);

			seq_putc(m, ' ');

			seq_putaccess(m, ex->access);

			seq_putc(m, '\n');

		}

	}

	rcu_read_unlock();