[PATCH 1/2] vfs: constify path argument to kernel_read_file_from_path

This patch constifies the path argument to kernel_read_file_from_path.

(Extracted from Helwig's patch.)
Signed-off-by: Mimi Zohar <redacted>
---
 fs/exec.c                  | 2 +-
 include/linux/fs.h         | 2 +-
 sound/oss/sound_firmware.h | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 62175cbcc801..54a4847649cc 100644
--- a/fs/exec.c
+++ b/fs/exec.c

@@ -974,7 +974,7 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
 }
 EXPORT_SYMBOL_GPL(kernel_read_file);
 
-int kernel_read_file_from_path(char *path, void **buf, loff_t *size,
+int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
 			       loff_t max_size, enum kernel_read_file_id id)
 {
 	struct file *file;

diff --git a/include/linux/fs.h b/include/linux/fs.h
index fdec9b763b54..d783cc8340de 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h

@@ -2775,7 +2775,7 @@ static inline const char *kernel_read_file_id_str(enum kernel_read_file_id id)
 extern int kernel_read(struct file *, loff_t, char *, unsigned long);
 extern int kernel_read_file(struct file *, void **, loff_t *, loff_t,
 			    enum kernel_read_file_id);
-extern int kernel_read_file_from_path(char *, void **, loff_t *, loff_t,
+extern int kernel_read_file_from_path(const char *, void **, loff_t *, loff_t,
 				      enum kernel_read_file_id);
 extern int kernel_read_file_from_fd(int, void **, loff_t *, loff_t,
 				    enum kernel_read_file_id);

diff --git a/sound/oss/sound_firmware.h b/sound/oss/sound_firmware.h
index da4c67e005ed..2be465277ba0 100644
--- a/sound/oss/sound_firmware.h
+++ b/sound/oss/sound_firmware.h

@@ -21,7 +21,7 @@ static inline int mod_firmware_load(const char *fn, char **fp)
 	loff_t size;
 	int err;
 
-	err = kernel_read_file_from_path((char *)fn, (void **)fp, &size,
+	err = kernel_read_file_from_path(fn, (void **)fp, &size,
 					 131072, READING_FIRMWARE);
 	if (err < 0)
 		return 0;

-- 
2.7.4

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From: Christoph Hellwig <hch@lst.de>

The CONFIG_IMA_LOAD_X509 and CONFIG_EVM_LOAD_X509 options permit
loading x509 signed certificates onto the trusted keyrings without
verifying the x509 certificate file's signature.

This patch replaces the call to the integrity_read_file() specific
function with the common kernel_read_file_from_path() function.
To avoid verifying the file signature, this patch defines
READING_X509_CERTFICATE.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mimi Zohar <redacted>

---
Changelog:
- rewrote patch description
- fixed parameters to kernel_read_file_from_path() and key_create_or_update()
- defined READING_X509_CERTIFICATE, a new __kernel_read_file enumeration
- removed constify change
---
 include/linux/fs.h                |  1 +
 security/integrity/digsig.c       | 14 +++++++----
 security/integrity/iint.c         | 49 ---------------------------------------
 security/integrity/ima/ima_main.c |  4 ++++
 security/integrity/integrity.h    |  2 --
 5 files changed, 14 insertions(+), 56 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index d783cc8340de..e522d25d0836 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h

@@ -2751,6 +2751,7 @@ extern int do_pipe_flags(int *, int);
 	id(KEXEC_IMAGE, kexec-image)		\
 	id(KEXEC_INITRAMFS, kexec-initramfs)	\
 	id(POLICY, security-policy)		\
+	id(X509_CERTIFICATE, x509-certificate)	\
 	id(MAX_ID, )
 
 #define __fid_enumify(ENUM, dummy) READING_ ## ENUM,

diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index 06554c448dce..6f9e4ce568cd 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c

@@ -112,21 +112,25 @@ int __init integrity_init_keyring(const unsigned int id)
 int __init integrity_load_x509(const unsigned int id, const char *path)
 {
 	key_ref_t key;
-	char *data;
+	void *data;
+	loff_t size;
 	int rc;
 
 	if (!keyring[id])
 		return -EINVAL;
 
-	rc = integrity_read_file(path, &data);
-	if (rc < 0)
+	rc = kernel_read_file_from_path(path, &data, &size, 0,
+					READING_X509_CERTIFICATE);
+	if (rc < 0) {
+		pr_err("Unable to open file: %s (%d)", path, rc);
 		return rc;
+	}
 
 	key = key_create_or_update(make_key_ref(keyring[id], 1),
 				   "asymmetric",
 				   NULL,
 				   data,
-				   rc,
+				   size,
 				   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
 				    KEY_USR_VIEW | KEY_USR_READ),
 				   KEY_ALLOC_NOT_IN_QUOTA);

@@ -139,6 +143,6 @@ int __init integrity_load_x509(const unsigned int id, const char *path)
 			  key_ref_to_ptr(key)->description, path);
 		key_ref_put(key);
 	}
-	kfree(data);
+	vfree(data);
 	return 0;
 }

diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index 6fc888ca468e..c84e05866052 100644
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c

@@ -200,55 +200,6 @@ int integrity_kernel_read(struct file *file, loff_t offset,
 }
 
 /*
- * integrity_read_file - read entire file content into the buffer
- *
- * This is function opens a file, allocates the buffer of required
- * size, read entire file content to the buffer and closes the file
- *
- * It is used only by init code.
- *
- */
-int __init integrity_read_file(const char *path, char **data)
-{
-	struct file *file;
-	loff_t size;
-	char *buf;
-	int rc = -EINVAL;
-
-	if (!path || !*path)
-		return -EINVAL;
-
-	file = filp_open(path, O_RDONLY, 0);
-	if (IS_ERR(file)) {
-		rc = PTR_ERR(file);
-		pr_err("Unable to open file: %s (%d)", path, rc);
-		return rc;
-	}
-
-	size = i_size_read(file_inode(file));
-	if (size <= 0)
-		goto out;
-
-	buf = kmalloc(size, GFP_KERNEL);
-	if (!buf) {
-		rc = -ENOMEM;
-		goto out;
-	}
-
-	rc = integrity_kernel_read(file, 0, buf, size);
-	if (rc == size) {
-		*data = buf;
-	} else {
-		kfree(buf);
-		if (rc >= 0)
-			rc = -EIO;
-	}
-out:
-	fput(file);
-	return rc;
-}
-
-/*
  * integrity_load_keys - load integrity keys hook
  *
  * Hooks is called from init/main.c:kernel_init_freeable()

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index b00186914df8..72bd2b666a31 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c

@@ -413,6 +413,10 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
 	if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
 		return 0;
 
+	/* permit signed certs */
+	if (!file && read_id == READING_X509_CERTIFICATE)
+		return 0;
+
 	if (!file || !buf || size == 0) { /* should never happen */
 		if (ima_appraise & IMA_APPRAISE_ENFORCE)
 			return -EACCES;

diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index a53e7e4ab06c..e1bf040fb110 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h

@@ -120,8 +120,6 @@ struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
 int integrity_kernel_read(struct file *file, loff_t offset,
 			  void *addr, unsigned long count);
 
-int __init integrity_read_file(const char *path, char **data);
-
 #define INTEGRITY_KEYRING_EVM		0
 #define INTEGRITY_KEYRING_IMA		1
 #define INTEGRITY_KEYRING_MODULE	2

-- 
2.7.4

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On Tue, Sep 12, 2017 at 10:45:33PM -0400, Mimi Zohar wrote:

This patch constifies the path argument to kernel_read_file_from_path.

(Extracted from Helwig's patch.)

Feel free to skip this given that it's trivial and you misspelled my
name anyway :)
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On Tue, 12 Sep 2017, Mimi Zohar wrote:

From: Christoph Hellwig <hch@lst.de>

The CONFIG_IMA_LOAD_X509 and CONFIG_EVM_LOAD_X509 options permit
loading x509 signed certificates onto the trusted keyrings without
verifying the x509 certificate file's signature.

This patch replaces the call to the integrity_read_file() specific
function with the common kernel_read_file_from_path() function.
To avoid verifying the file signature, this patch defines
READING_X509_CERTFICATE.

So, to be clear, this patch solves the XFS deadlock using a different 
approach (to the now reverted integrity_read approach), which Christoph 
also says is more correct generally.  Correct?

What testing has this had?

Should this go in with the rest of the security changes now or wait until 
either -rc or the next merge window?


-- 
James Morris
[off-list ref]

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On Fri, Sep 15, 2017 at 06:21:28AM +1000, James Morris wrote:

So, to be clear, this patch solves the XFS deadlock using a different 
approach (to the now reverted integrity_read approach), which Christoph 
also says is more correct generally.  Correct?

No.  It is in addition to the previous patches - the patches were
correct for the IMA interaction with the I/O path.  It just turns
out that the function was also reused for reading certificates
at initialization time, for which that change was incorrect.

If this series is applied first the integrity_read code is not
used for that path any more.
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On Thu, 14 Sep 2017, Christoph Hellwig wrote:

On Fri, Sep 15, 2017 at 06:21:28AM +1000, James Morris wrote:

quoted

So, to be clear, this patch solves the XFS deadlock using a different 
approach (to the now reverted integrity_read approach), which Christoph 
also says is more correct generally.  Correct?

No.  It is in addition to the previous patches - the patches were
correct for the IMA interaction with the I/O path.  It just turns
out that the function was also reused for reading certificates
at initialization time, for which that change was incorrect.

If this series is applied first the integrity_read code is not
used for that path any more.

Ok, Mimi, please post a complete patchset for this issue against my -next 
branch.


-- 
James Morris
[off-list ref]

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On Thu, 14 Sep 2017, Christoph Hellwig wrote:

On Fri, Sep 15, 2017 at 06:21:28AM +1000, James Morris wrote:

quoted

So, to be clear, this patch solves the XFS deadlock using a different 
approach (to the now reverted integrity_read approach), which Christoph 
also says is more correct generally.  Correct?

No.  It is in addition to the previous patches - the patches were
correct for the IMA interaction with the I/O path.  It just turns
out that the function was also reused for reading certificates
at initialization time, for which that change was incorrect.

If this series is applied first the integrity_read code is not
used for that path any more.

Ok.  Sorry I hadn't looked at the code in detail at this stage during the 
conference and wanting to just revert back to something that Linus can 
safely pull before the merge window closes.


-- 
James Morris
[off-list ref]

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