diff options
| author | Mimi Zohar <zohar@linux.ibm.com> | 2023-10-18 21:47:02 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-11-28 19:56:29 +0300 |
| commit | 5ff849948c11950f5abe35c4c0f1e753fa2ec9ca (patch) | |
| tree | a92e698c624298d820197177a5e26221244ddbef /security | |
| parent | 4584a421a6d965e060e40de6c382fab5872ec4ba (diff) | |
| download | linux-5ff849948c11950f5abe35c4c0f1e753fa2ec9ca.tar.xz | |
ima: detect changes to the backing overlay file
commit b836c4d29f2744200b2af41e14bf50758dddc818 upstream.
Commit 18b44bc5a672 ("ovl: Always reevaluate the file signature for
IMA") forced signature re-evaulation on every file access.
Instead of always re-evaluating the file's integrity, detect a change
to the backing file, by comparing the cached file metadata with the
backing file's metadata. Verifying just the i_version has not changed
is insufficient. In addition save and compare the i_ino and s_dev
as well.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Tested-by: Eric Snowberg <eric.snowberg@oracle.com>
Tested-by: Raul E Rangel <rrangel@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'security')
| -rw-r--r-- | security/integrity/ima/ima_api.c | 5 | ||||
| -rw-r--r-- | security/integrity/ima/ima_main.c | 16 | ||||
| -rw-r--r-- | security/integrity/integrity.h | 2 |
3 files changed, 22 insertions, 1 deletions
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index 2c6c3a5228b5..04b9e465463b 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -216,6 +216,7 @@ int ima_collect_measurement(struct integrity_iint_cache *iint, { const char *audit_cause = "failed"; struct inode *inode = file_inode(file); + struct inode *real_inode = d_real_inode(file_dentry(file)); const char *filename = file->f_path.dentry->d_name.name; int result = 0; int length; @@ -266,6 +267,10 @@ int ima_collect_measurement(struct integrity_iint_cache *iint, iint->ima_hash = tmpbuf; memcpy(iint->ima_hash, &hash, length); iint->version = i_version; + if (real_inode != inode) { + iint->real_ino = real_inode->i_ino; + iint->real_dev = real_inode->i_sb->s_dev; + } /* Possibly temporary failure due to type of read (eg. O_DIRECT) */ if (!result) diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index e9a361109dd2..7cd9df849929 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -26,6 +26,7 @@ #include <linux/ima.h> #include <linux/iversion.h> #include <linux/fs.h> +#include <linux/iversion.h> #include "ima.h" @@ -202,7 +203,7 @@ static int process_measurement(struct file *file, const struct cred *cred, u32 secid, char *buf, loff_t size, int mask, enum ima_hooks func) { - struct inode *inode = file_inode(file); + struct inode *backing_inode, *inode = file_inode(file); struct integrity_iint_cache *iint = NULL; struct ima_template_desc *template_desc = NULL; char *pathbuf = NULL; @@ -278,6 +279,19 @@ static int process_measurement(struct file *file, const struct cred *cred, iint->measured_pcrs = 0; } + /* Detect and re-evaluate changes made to the backing file. */ + backing_inode = d_real_inode(file_dentry(file)); + if (backing_inode != inode && + (action & IMA_DO_MASK) && (iint->flags & IMA_DONE_MASK)) { + if (!IS_I_VERSION(backing_inode) || + backing_inode->i_sb->s_dev != iint->real_dev || + backing_inode->i_ino != iint->real_ino || + !inode_eq_iversion(backing_inode, iint->version)) { + iint->flags &= ~IMA_DONE_MASK; + iint->measured_pcrs = 0; + } + } + /* Determine if already appraised/measured based on bitmask * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED, * IMA_AUDIT, IMA_AUDITED) diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index 547425c20e11..06b0cb5ebaf4 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -131,6 +131,8 @@ struct integrity_iint_cache { unsigned long flags; unsigned long measured_pcrs; unsigned long atomic_flags; + unsigned long real_ino; + dev_t real_dev; enum integrity_status ima_file_status:4; enum integrity_status ima_mmap_status:4; enum integrity_status ima_bprm_status:4; |