Some filesystems do not export the filesystem's magic number, as it is considered internal, private data. In other cases, the policy rule needs to identify a specifically mounted filesystem (eg. rootfs).
This patch defines a new IMA policy condition named "fsname", based on the superblock's file_system_type (sb->s_type) name. By defining a policy rule in terms of the filesystem magic number and the superblock filesystem name, files on the rootfs filesystem are only appraised, when rootfs is a tmpfs filesystem, which supports xattrs. Sample rules: measure func=FILE_CHECK fsname=xfs appraise fsmagic=0x01021994 fsname=rootfs Suggested-by: Dave Chinner <[email protected]> Signed-off-by: Mimi Zohar <[email protected]> --- Documentation/ABI/testing/ima_policy | 2 +- security/integrity/ima/ima_policy.c | 25 ++++++++++++++++++++++++- 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index b0e8143c681f..281b88d17a37 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -21,7 +21,7 @@ Description: audit | hash | dont_hash condition:= base | lsm [option] base: [[func=] [mask=] [fsmagic=] [fsuuid=] [uid=] - [euid=] [fowner=]] + [euid=] [fowner=] [fsname=]] lsm: [[subj_user=] [subj_role=] [subj_type=] [obj_user=] [obj_role=] [obj_type=]] option: [[appraise_type=]] [permit_directio] [force] diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 878ae1a06e1e..ceffb98d79ca 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -33,6 +33,7 @@ #define IMA_INMASK 0x0040 #define IMA_EUID 0x0080 #define IMA_PCR 0x0100 +#define IMA_FSNAME 0x0200 #define UNKNOWN 0 #define MEASURE 0x0001 /* same as IMA_MEASURE */ @@ -74,6 +75,7 @@ struct ima_rule_entry { void *args_p; /* audit value */ int type; /* audit type */ } lsm[MAX_LSM_RULES]; + char *fsname; }; /* @@ -267,6 +269,9 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, if ((rule->flags & IMA_FSMAGIC) && rule->fsmagic != inode->i_sb->s_magic) return false; + if ((rule->flags & IMA_FSNAME) + && strcmp(rule->fsname, inode->i_sb->s_type->name)) + return false; if ((rule->flags & IMA_FSUUID) && !uuid_equal(&rule->fsuuid, &inode->i_sb->s_uuid)) return false; @@ -528,7 +533,7 @@ enum { Opt_audit, Opt_hash, Opt_dont_hash, Opt_obj_user, Opt_obj_role, Opt_obj_type, Opt_subj_user, Opt_subj_role, Opt_subj_type, - Opt_func, Opt_mask, Opt_fsmagic, + Opt_func, Opt_mask, Opt_fsmagic, Opt_fsname, Opt_fsuuid, Opt_uid_eq, Opt_euid_eq, Opt_fowner_eq, Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt, Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt, @@ -553,6 +558,7 @@ static match_table_t policy_tokens = { {Opt_func, "func=%s"}, {Opt_mask, "mask=%s"}, {Opt_fsmagic, "fsmagic=%s"}, + {Opt_fsname, "fsname=%s"}, {Opt_fsuuid, "fsuuid=%s"}, {Opt_uid_eq, "uid=%s"}, {Opt_euid_eq, "euid=%s"}, @@ -763,6 +769,17 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) if (!result) entry->flags |= IMA_FSMAGIC; break; + case Opt_fsname: + ima_log_string(ab, "fsname", args[0].from); + + entry->fsname = kstrdup(args[0].from, GFP_KERNEL); + if (!entry->fsname) { + result = -ENOMEM; + break; + } + result = 0; + entry->flags |= IMA_FSNAME; + break; case Opt_fsuuid: ima_log_string(ab, "fsuuid", args[0].from); @@ -1094,6 +1111,12 @@ int ima_policy_show(struct seq_file *m, void *v) seq_puts(m, " "); } + if (entry->flags & IMA_FSNAME) { + snprintf(tbuf, sizeof(tbuf), "%s", entry->fsname); + seq_printf(m, pt(Opt_fsname), tbuf); + seq_puts(m, " "); + } + if (entry->flags & IMA_PCR) { snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr); seq_printf(m, pt(Opt_pcr), tbuf); -- 2.7.4
