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Subject[PATCH 03/12] ima: generalize policy file operations
Date
This patch renames ima_open_policy() and ima_release_policy() respectively
to ima_open_data_upload() and ima_release_data_upload(). They will be used
to implement file operations for interfaces allowing to upload and read
provided data.

Also, the new flag IMA_POLICY_BUSY has been defined specifically for
the policy, as it might not be cleared at file release. This would prevent
userspace applications from uploading files after a policy has been loaded.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima_fs.c | 46 ++++++++++++++++++++++++++++-------------
1 file changed, 32 insertions(+), 14 deletions(-)

diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index e375206..f4199f2 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -384,6 +384,7 @@ static ssize_t ima_write_data(struct file *file, const char __user *buf,
}

enum ima_fs_flags {
+ IMA_POLICY_BUSY,
IMA_FS_BUSY,
};

@@ -399,22 +400,33 @@ static const struct seq_operations ima_policy_seqops = {
#endif

/*
- * ima_open_policy: sequentialize access to the policy file
+ * ima_open_data_upload: sequentialize access to the data upload interface
*/
-static int ima_open_policy(struct inode *inode, struct file *filp)
+static int ima_open_data_upload(struct inode *inode, struct file *filp)
{
+ enum kernel_read_file_id file_id = ima_get_file_id(filp->f_path.dentry);
+ const struct seq_operations *seq_ops = NULL;
+ enum ima_fs_flags flag = IMA_FS_BUSY;
+ bool read_allowed = false;
+
+ if (file_id == READING_POLICY) {
+ flag = IMA_POLICY_BUSY;
+#ifdef CONFIG_IMA_READ_POLICY
+ read_allowed = true;
+ seq_ops = &ima_policy_seqops;
+#endif
+ }
+
if (!(filp->f_flags & O_WRONLY)) {
-#ifndef CONFIG_IMA_READ_POLICY
- return -EACCES;
-#else
+ if (!read_allowed)
+ return -EACCES;
if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
return -EACCES;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- return seq_open(filp, &ima_policy_seqops);
-#endif
+ return seq_open(filp, seq_ops);
}
- if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags))
+ if (test_and_set_bit(flag, &ima_fs_flags))
return -EBUSY;
return 0;
}
@@ -426,13 +438,19 @@ static int ima_open_policy(struct inode *inode, struct file *filp)
* point to the new policy rules, and remove the securityfs policy file,
* assuming a valid policy.
*/
-static int ima_release_policy(struct inode *inode, struct file *file)
+static int ima_release_data_upload(struct inode *inode, struct file *file)
{
+ enum kernel_read_file_id file_id = ima_get_file_id(file->f_path.dentry);
const char *cause = valid_policy ? "completed" : "failed";

if ((file->f_flags & O_ACCMODE) == O_RDONLY)
return seq_release(inode, file);

+ if (file_id != READING_POLICY) {
+ clear_bit(IMA_FS_BUSY, &ima_fs_flags);
+ return 0;
+ }
+
if (valid_policy && ima_check_policy() < 0) {
cause = "failed";
valid_policy = 0;
@@ -454,16 +472,16 @@ static int ima_release_policy(struct inode *inode, struct file *file)
securityfs_remove(ima_policy);
ima_policy = NULL;
#else
- clear_bit(IMA_FS_BUSY, &ima_fs_flags);
+ clear_bit(IMA_POLICY_BUSY, &ima_fs_flags);
#endif
return 0;
}

-static const struct file_operations ima_measure_policy_ops = {
- .open = ima_open_policy,
+static const struct file_operations ima_data_upload_ops = {
+ .open = ima_open_data_upload,
.write = ima_write_data,
.read = seq_read,
- .release = ima_release_policy,
+ .release = ima_release_data_upload,
.llseek = generic_file_llseek,
};

@@ -502,7 +520,7 @@ int __init ima_fs_init(void)

ima_policy = securityfs_create_file("policy", POLICY_FILE_FLAGS,
ima_dir, NULL,
- &ima_measure_policy_ops);
+ &ima_data_upload_ops);
if (IS_ERR(ima_policy))
goto out;

--
2.9.3
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