5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Andreev [ Upstream commit a7c44fd9f80e37763acf9cd3c87a58058d206427 ] Both smackfs/direct and smackfs/mapped incorrectly accept the full range of integer values. For example: # cd /sys/fs/smackfs/ # cat direct ; echo 250 # cat cipso2 @ 250/2 _ 250/2,4,5,6,7,8 * 250/3,5,7 ^ 250/2,4,5,6,7 ? 250/3,4,5,6,7,8 # echo -1234 >direct ; cat direct ; echo -1234 # cat cipso2 @ -1234/2 _ -1234/2,4,5,6,7,8 * -1234/3,5,7 ^ -1234/2,4,5,6,7 ? -1234/3,4,5,6,7,8 # I noticed two things regarding this: 1) sensitivity levels are truncated to 8 bits when labeling outgoing packets (0x2e = 46 for the -1234 example above) 2) the reverse process fails: incoming packets with sensitivity level 46 do not match these smackfs/cipso2 entries. Even observation (1) on its own warrants a fix. This patch restricts smackfs/direct and smackfs/mapped accepted values to the 0-255 range. Fixes: e114e473771c ("Smack: Simplified Mandatory Access Control Kernel") Signed-off-by: Konstantin Andreev Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin --- security/smack/smack.h | 2 +- security/smack/smackfs.c | 26 ++++++++++++++------------ 2 files changed, 15 insertions(+), 13 deletions(-) diff --git a/security/smack/smack.h b/security/smack/smack.h index 63acf60481a26..9bee6a8799643 100644 --- a/security/smack/smack.h +++ b/security/smack/smack.h @@ -304,7 +304,7 @@ int smack_populate_secattr(struct smack_known *skp); * Shared data. */ extern int smack_enabled __initdata; -extern int smack_cipso_auto_level[2]; +extern u8 smack_cipso_auto_level[2]; #define smack_cipso_direct (+smack_cipso_auto_level[0]) #define smack_cipso_mapped (+smack_cipso_auto_level[1]) extern struct smack_known *smack_net_ambient; diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index 594111ccb098c..575f481878253 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -91,7 +91,7 @@ struct smack_known *smack_net_ambient; * secid is contained directly in the category set. * It can be reset via smackfs/mapped */ -int smack_cipso_auto_level[2] = { +u8 smack_cipso_auto_level[2] = { SMACK_CIPSO_DIRECT_DEFAULT, SMACK_CIPSO_MAPPED_DEFAULT, }; @@ -1659,17 +1659,15 @@ static const struct file_operations smk_doi_ops = { static ssize_t smk_read_cipso_auto_level(struct file *filp, char __user *buf, size_t count, loff_t *ppos) { - char temp[80]; - ssize_t rc; + char temp[sizeof "255"]; + int n; if (*ppos != 0) return 0; - sprintf(temp, "%d", smack_cipso_auto_level[ - smk_cipso_auto_level_idx(filp)]); - rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp)); - - return rc; + n = sprintf(temp, "%u", (unsigned int)smack_cipso_auto_level[ + smk_cipso_auto_level_idx(filp)]); + return simple_read_from_buffer(buf, count, ppos, temp, n); } /** @@ -1685,13 +1683,16 @@ static ssize_t smk_write_cipso_auto_level(struct file *filp, const char __user *buf, size_t count, loff_t *ppos) { - struct smack_known *skp; - int i, ret, idx, old_lvl; + int ret, idx; + u8 i, old_lvl; if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM; - - ret = kstrtos32_from_user(buf, count, 10, &i); + /* + * draft-ietf-cipso-ipsecurity-01 (CIPSO 2.2), 3.4.2.4: + * "Sensitivity Level is 1 octet in length. Its value is from 0 to 255" + */ + ret = kstrtou8_from_user(buf, count, 10, &i); if (unlikely(ret)) return ret; @@ -1704,6 +1705,7 @@ smk_write_cipso_auto_level(struct file *filp, const char __user *buf, old_lvl = smack_cipso_auto_level[idx]; if (old_lvl != i) { + struct smack_known *skp; mutex_lock(&smack_known_lock); list_for_each_entry_rcu(skp, &smack_known_list, list) if (skp->smk_netlabel.attr.mls.lvl == -- 2.53.0