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selinux: improve error checking in sel_write_load()

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Move our existing input sanity checking to the top of sel_write_load()
and add a check to ensure the buffer size is non-zero.

Move a local variable initialization from the declaration to before it
is used.

Minor style adjustments.

Reported-by: Sam Sun <samsun1006219@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Paul Moore 2024-03-04 22:12:22 -05:00
parent e6b5ebca41
commit 42c7732380
1 changed files with 16 additions and 14 deletions
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28
security/selinux/selinuxfs.c
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@ -571,11 +571,18 @@ static ssize_t sel_write_load(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct selinux_fs_info *fsi = file_inode(file)->i_sb->s_fs_info;
struct selinux_fs_info *fsi;
struct selinux_load_state load_state;
ssize_t length;
void *data = NULL;
/* no partial writes */
if (*ppos)
return -EINVAL;
/* no empty policies */
if (!count)
return -EINVAL;
mutex_lock(&selinux_state.policy_mutex);
length = avc_has_perm(current_sid(), SECINITSID_SECURITY,
@ -583,26 +590,22 @@ static ssize_t sel_write_load(struct file *file, const char __user *buf,
if (length)
goto out;
/* No partial writes. */
length = -EINVAL;
if (*ppos != 0)
goto out;
length = -ENOMEM;
data = vmalloc(count);
if (!data)
if (!data) {
length = -ENOMEM;
goto out;
}
if (copy_from_user(data, buf, count) != 0) {
length = -EFAULT;
if (copy_from_user(data, buf, count) != 0)
goto out;
}
length = security_load_policy(data, count, &load_state);
if (length) {
pr_warn_ratelimited("SELinux: failed to load policy\n");
goto out;
}
fsi = file_inode(file)->i_sb->s_fs_info;
length = sel_make_policy_nodes(fsi, load_state.policy);
if (length) {
pr_warn_ratelimited("SELinux: failed to initialize selinuxfs\n");
@ -611,13 +614,12 @@ static ssize_t sel_write_load(struct file *file, const char __user *buf,
}
selinux_policy_commit(&load_state);
length = count;
audit_log(audit_context(), GFP_KERNEL, AUDIT_MAC_POLICY_LOAD,
"auid=%u ses=%u lsm=selinux res=1",
from_kuid(&init_user_ns, audit_get_loginuid(current)),
audit_get_sessionid(current));
out:
mutex_unlock(&selinux_state.policy_mutex);
vfree(data);