From: Mimi Zohar Date: Mon, 27 Jan 2025 15:24:13 +0000 (-0500) Subject: ima: limit the number of open-writers integrity violations X-Git-Tag: v6.15-rc1~129^2~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5b3cd801155f0b34b0b95942a5b057c9b8cad33e;p=thirdparty%2Fkernel%2Flinux.git ima: limit the number of open-writers integrity violations Each time a file in policy, that is already opened for write, is opened for read, an open-writers integrity violation audit message is emitted and a violation record is added to the IMA measurement list. This occurs even if an open-writers violation has already been recorded. Limit the number of open-writers integrity violations for an existing file open for write to one. After the existing file open for write closes (__fput), subsequent open-writers integrity violations may be emitted. Cc: stable@vger.kernel.org # applies cleanly up to linux-6.6 Tested-by: Stefan Berger Reviewed-by: Petr Vorel Tested-by: Petr Vorel Reviewed-by: Roberto Sassu Signed-off-by: Mimi Zohar --- diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index a4f284bd846c1..3423b3088de50 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -182,6 +182,7 @@ struct ima_kexec_hdr { #define IMA_CHANGE_ATTR 2 #define IMA_DIGSIG 3 #define IMA_MUST_MEASURE 4 +#define IMA_EMITTED_OPENWRITERS 5 /* IMA integrity metadata associated with an inode */ struct ima_iint_cache { diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 28b8b0db6f9bb..95118c1887cb6 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -137,8 +137,13 @@ static void ima_rdwr_violation_check(struct file *file, } else { if (must_measure) set_bit(IMA_MUST_MEASURE, &iint->atomic_flags); - if (inode_is_open_for_write(inode) && must_measure) - send_writers = true; + + /* Limit number of open_writers violations */ + if (inode_is_open_for_write(inode) && must_measure) { + if (!test_and_set_bit(IMA_EMITTED_OPENWRITERS, + &iint->atomic_flags)) + send_writers = true; + } } if (!send_tomtou && !send_writers) @@ -167,6 +172,8 @@ static void ima_check_last_writer(struct ima_iint_cache *iint, if (atomic_read(&inode->i_writecount) == 1) { struct kstat stat; + clear_bit(IMA_EMITTED_OPENWRITERS, &iint->atomic_flags); + update = test_and_clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags); if ((iint->flags & IMA_NEW_FILE) ||