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authorJann Horn <jannh@google.com>2019-04-10 09:55:48 -0700
committerMicah Morton <mortonm@chromium.org>2019-07-15 08:07:09 -0700
commit78ae7df96d647627ceae0b65eea9e4f83a0a4b66 (patch)
tree1f7f4fb2c97ee93390fe7527e4d026ee87214422 /security/safesetid
parent8068866c4af124345e2a129be921278aada7830f (diff)
downloadlinux-78ae7df96d647627ceae0b65eea9e4f83a0a4b66.tar.bz2
LSM: SafeSetID: refactor policy parsing
In preparation for changing the policy parsing logic, refactor the line parsing logic to be less verbose and move it into a separate function. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Micah Morton <mortonm@chromium.org>
Diffstat (limited to 'security/safesetid')
-rw-r--r--security/safesetid/securityfs.c84
1 files changed, 33 insertions, 51 deletions
diff --git a/security/safesetid/securityfs.c b/security/safesetid/securityfs.c
index 2c6c829be044..90784a8d950a 100644
--- a/security/safesetid/securityfs.c
+++ b/security/safesetid/securityfs.c
@@ -33,68 +33,50 @@ static struct safesetid_file_entry safesetid_files[] = {
/*
* In the case the input buffer contains one or more invalid UIDs, the kuid_t
- * variables pointed to by 'parent' and 'child' will get updated but this
+ * variables pointed to by @parent and @child will get updated but this
* function will return an error.
+ * Contents of @buf may be modified.
*/
-static int parse_safesetid_whitelist_policy(const char __user *buf,
- size_t len,
- kuid_t *parent,
- kuid_t *child)
+static int parse_policy_line(
+ struct file *file, char *buf, kuid_t *parent, kuid_t *child)
{
- char *kern_buf;
- char *parent_buf;
- char *child_buf;
- const char separator[] = ":";
+ char *child_str;
int ret;
- size_t first_substring_length;
- long parsed_parent;
- long parsed_child;
+ u32 parsed_parent, parsed_child;
- /* Duplicate string from user memory and NULL-terminate */
- kern_buf = memdup_user_nul(buf, len);
- if (IS_ERR(kern_buf))
- return PTR_ERR(kern_buf);
-
- /*
- * Format of |buf| string should be <UID>:<UID>.
- * Find location of ":" in kern_buf (copied from |buf|).
- */
- first_substring_length = strcspn(kern_buf, separator);
- if (first_substring_length == 0 || first_substring_length == len) {
- ret = -EINVAL;
- goto free_kern;
- }
-
- parent_buf = kmemdup_nul(kern_buf, first_substring_length, GFP_KERNEL);
- if (!parent_buf) {
- ret = -ENOMEM;
- goto free_kern;
- }
+ /* Format of |buf| string should be <UID>:<UID>. */
+ child_str = strchr(buf, ':');
+ if (child_str == NULL)
+ return -EINVAL;
+ *child_str = '\0';
+ child_str++;
- ret = kstrtol(parent_buf, 0, &parsed_parent);
+ ret = kstrtou32(buf, 0, &parsed_parent);
if (ret)
- goto free_both;
+ return ret;
- child_buf = kern_buf + first_substring_length + 1;
- ret = kstrtol(child_buf, 0, &parsed_child);
+ ret = kstrtou32(child_str, 0, &parsed_child);
if (ret)
- goto free_both;
+ return ret;
*parent = make_kuid(current_user_ns(), parsed_parent);
- if (!uid_valid(*parent)) {
- ret = -EINVAL;
- goto free_both;
- }
-
*child = make_kuid(current_user_ns(), parsed_child);
- if (!uid_valid(*child)) {
- ret = -EINVAL;
- goto free_both;
- }
+ if (!uid_valid(*parent) || !uid_valid(*child))
+ return -EINVAL;
-free_both:
- kfree(parent_buf);
-free_kern:
+ return 0;
+}
+
+static int parse_safesetid_whitelist_policy(
+ struct file *file, const char __user *buf, size_t len,
+ kuid_t *parent, kuid_t *child)
+{
+ char *kern_buf = memdup_user_nul(buf, len);
+ int ret;
+
+ if (IS_ERR(kern_buf))
+ return PTR_ERR(kern_buf);
+ ret = parse_policy_line(file, kern_buf, parent, child);
kfree(kern_buf);
return ret;
}
@@ -121,8 +103,8 @@ static ssize_t safesetid_file_write(struct file *file,
flush_safesetid_whitelist_entries();
break;
case SAFESETID_WHITELIST_ADD:
- ret = parse_safesetid_whitelist_policy(buf, len, &parent,
- &child);
+ ret = parse_safesetid_whitelist_policy(file, buf, len,
+ &parent, &child);
if (ret)
return ret;