kernel.git/security/smack/smack.h, branch linux-3.2.y

smack: fix possible use after frees in task_security() callers

2015-05-09T22:16:13Z

commit 6d1cff2a885850b78b40c34777b46cf5da5d1050 upstream. We hit use after free on dereferncing pointer to task_smack struct in smk_of_task() called from smack_task_to_inode(). task_security() macro uses task_cred_xxx() to get pointer to the task_smack. task_cred_xxx() could be used only for non-pointer members of task's credentials. It cannot be used for pointer members since what they point to may disapper after dropping RCU read lock. Mainly task_security() used this way: smk_of_task(task_security(p)) Intead of this introduce function smk_of_task_struct() which takes task_struct as argument and returns pointer to smk_known struct and do this under RCU read lock. Bogus task_security() macro is not used anymore, so remove it. KASan's report for this: AddressSanitizer: use after free in smack_task_to_inode+0x50/0x70 at addr c4635600 ============================================================================= BUG kmalloc-64 (Tainted: PO): kasan error ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Allocated in new_task_smack+0x44/0xd8 age=39 cpu=0 pid=1866 kmem_cache_alloc_trace+0x88/0x1bc new_task_smack+0x44/0xd8 smack_cred_prepare+0x48/0x21c security_prepare_creds+0x44/0x4c prepare_creds+0xdc/0x110 smack_setprocattr+0x104/0x150 security_setprocattr+0x4c/0x54 proc_pid_attr_write+0x12c/0x194 vfs_write+0x1b0/0x370 SyS_write+0x5c/0x94 ret_fast_syscall+0x0/0x48 INFO: Freed in smack_cred_free+0xc4/0xd0 age=27 cpu=0 pid=1564 kfree+0x270/0x290 smack_cred_free+0xc4/0xd0 security_cred_free+0x34/0x3c put_cred_rcu+0x58/0xcc rcu_process_callbacks+0x738/0x998 __do_softirq+0x264/0x4cc do_softirq+0x94/0xf4 irq_exit+0xbc/0x120 handle_IRQ+0x104/0x134 gic_handle_irq+0x70/0xac __irq_svc+0x44/0x78 _raw_spin_unlock+0x18/0x48 sync_inodes_sb+0x17c/0x1d8 sync_filesystem+0xac/0xfc vdfs_file_fsync+0x90/0xc0 vfs_fsync_range+0x74/0x7c INFO: Slab 0xd3b23f50 objects=32 used=31 fp=0xc4635600 flags=0x4080 INFO: Object 0xc4635600 @offset=5632 fp=0x (null) Bytes b4 c46355f0: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ Object c4635600: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object c4635610: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object c4635620: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object c4635630: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkkkkkk. Redzone c4635640: bb bb bb bb .... Padding c46356e8: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ Padding c46356f8: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ CPU: 5 PID: 834 Comm: launchpad_prelo Tainted: PBO 3.10.30 #1 Backtrace: [] (dump_backtrace+0x0/0x158) from [] (show_stack+0x20/0x24) r7:c4634010 r6:d3b23f50 r5:c4635600 r4:d1002140 [] (show_stack+0x0/0x24) from [] (dump_stack+0x20/0x28) [] (dump_stack+0x0/0x28) from [] (print_trailer+0x124/0x144) [] (print_trailer+0x0/0x144) from [] (object_err+0x3c/0x44) r7:c4635600 r6:d1002140 r5:d3b23f50 r4:c4635600 [] (object_err+0x0/0x44) from [] (kasan_report_error+0x2b8/0x538) r6:d1002140 r5:d3b23f50 r4:c6429cf8 r3:c09e1aa7 [] (kasan_report_error+0x0/0x538) from [] (__asan_load4+0xd4/0xf8) [] (__asan_load4+0x0/0xf8) from [] (smack_task_to_inode+0x50/0x70) r5:c4635600 r4:ca9da000 [] (smack_task_to_inode+0x0/0x70) from [] (security_task_to_inode+0x3c/0x44) r5:cca25e80 r4:c0ba9780 [] (security_task_to_inode+0x0/0x44) from [] (pid_revalidate+0x124/0x178) r6:00000000 r5:cca25e80 r4:cbabe3c0 r3:00008124 [] (pid_revalidate+0x0/0x178) from [] (lookup_fast+0x35c/0x43y4) r9:c6429efc r8:00000101 r7:c079d940 r6:c6429e90 r5:c6429ed8 r4:c83c4148 [] (lookup_fast+0x0/0x434) from [] (do_last.isra.24+0x1c0/0x1108) [] (do_last.isra.24+0x0/0x1108) from [] (path_openat.isra.25+0xf4/0x648) [] (path_openat.isra.25+0x0/0x648) from [] (do_filp_open+0x3c/0x88) [] (do_filp_open+0x0/0x88) from [] (do_sys_open+0xf0/0x198) r7:00000001 r6:c0ea2180 r5:0000000b r4:00000000 [] (do_sys_open+0x0/0x198) from [] (SyS_open+0x30/0x34) [] (SyS_open+0x0/0x34) from [] (ret_fast_syscall+0x0/0x48) Read of size 4 by thread T834: Memory state around the buggy address: c4635380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc c4635400: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc c4635480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc c4635500: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc c4635580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >c4635600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ c4635680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb c4635700: 00 00 00 00 04 fc fc fc fc fc fc fc fc fc fc fc c4635780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc c4635800: 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc fc c4635880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== Signed-off-by: Andrey Ryabinin [bwh: Backported to 3.2: - smk_of_task() and similar functions return char * not struct smack_known * - The callers of task_security() are quite different, but most can be changed to use smk_of_task_struct() just as in the upstream version - Use open-coded RCU locking in the one place using smk_of_forked() instead of smk_of_task()] Signed-off-by: Ben Hutchings

Smack: allow to access /smack/access as normal user

2011-10-20T23:07:31Z

Allow query access as a normal user removing the need for CAP_MAC_ADMIN. Give RW access to /smack/access for UGO. Do not import smack labels in access check. Signed-off-by: Jarkko Sakkinen Signed-off-by: Casey Schaufler

Smack: Clean up comments

2011-10-12T21:26:07Z

There are a number of comments in the Smack code that are either malformed or include code. This patch cleans them up. Signed-off-by: Casey Schaufler

Smack: Rule list lookup performance

2011-10-12T21:23:13Z

This patch is targeted for the smack-next tree. Smack access checks suffer from two significant performance issues. In cases where there are large numbers of rules the search of the single list of rules is wasteful. Comparing the string values of the smack labels is less efficient than a numeric comparison would. These changes take advantage of the Smack label list, which maintains the mapping of Smack labels to secids and optional CIPSO labels. Because the labels are kept perpetually, an access check can be done strictly based on the address of the label in the list without ever looking at the label itself. Rather than keeping one global list of rules the rules with a particular subject label can be based off of that label list entry. The access check need never look at entries that do not use the current subject label. This requires that packets coming off the network with CIPSO direct Smack labels that have never been seen before be treated carefully. The only case where they could be delivered is where the receiving socket has an IPIN star label, so that case is explicitly addressed. On a system with 39,800 rules (200 labels in all permutations) a system with this patch runs an access speed test in 5% of the time of the old version. That should be a best case improvement. If all of the rules are associated with the same subject label and all of the accesses are for processes with that label (unlikely) the improvement is about 30%. Signed-off-by: Casey Schaufler

LSM: separate LSM_AUDIT_DATA_DENTRY from LSM_AUDIT_DATA_PATH

2011-04-25T22:14:07Z

This patch separates and audit message that only contains a dentry from one that contains a full path. This allows us to make it harder to misuse the interfaces or for the interfaces to be implemented wrong. Signed-off-by: Eric Paris Acked-by: Casey Schaufler

LSM: split LSM_AUDIT_DATA_FS into _PATH and _INODE

2011-04-25T22:13:15Z

The lsm common audit code has wacky contortions making sure which pieces of information are set based on if it was given a path, dentry, or inode. Split this into path and inode to get rid of some of the code complexity. Signed-off-by: Eric Paris Acked-by: Casey Schaufler

security:smack: kill unused SMACK_LIST_MAX, MAY_ANY and MAY_ANYWRITE

2011-02-10T03:58:11Z

Kill unused macros of SMACK_LIST_MAX, MAY_ANY and MAY_ANYWRITE. v2: As Casey Schaufler's advice, also remove MAY_ANY. Signed-off-by: Shan Wei Signed-off-by: Casey Schaufler

Subject: [PATCH] Smack: mmap controls for library containment

2011-01-17T16:05:27Z

In the embedded world there are often situations where libraries are updated from a variety of sources, for a variety of reasons, and with any number of security characteristics. These differences might include privilege required for a given library provided interface to function properly, as occurs from time to time in graphics libraries. There are also cases where it is important to limit use of libraries based on the provider of the library and the security aware application may make choices based on that criteria. These issues are addressed by providing an additional Smack label that may optionally be assigned to an object, the SMACK64MMAP attribute. An mmap operation is allowed if there is no such attribute. If there is a SMACK64MMAP attribute the mmap is permitted only if a subject with that label has all of the access permitted a subject with the current task label. Security aware applications may from time to time wish to reduce their "privilege" to avoid accidental use of privilege. One case where this arises is the environment in which multiple sources provide libraries to perform the same functions. An application may know that it should eschew services made available from a particular vendor, or of a particular version. In support of this a secondary list of Smack rules has been added that is local to the task. This list is consulted only in the case where the global list has approved access. It can only further restrict access. Unlike the global last, if no entry is found on the local list access is granted. An application can add entries to its own list by writing to /smack/load-self. The changes appear large as they involve refactoring the list handling to accomodate there being more than one rule list. Signed-off-by: Casey Schaufler

Smack: Transmute labels on specified directories

2010-12-07T22:04:02Z

In a situation where Smack access rules allow processes with multiple labels to write to a directory it is easy to get into a situation where the directory gets cluttered with files that the owner can't deal with because while they could be written to the directory a process at the label of the directory can't write them. This is generally the desired behavior, but when it isn't it is a real issue. This patch introduces a new attribute SMACK64TRANSMUTE that instructs Smack to create the file with the label of the directory under certain circumstances. A new access mode, "t" for transmute, is made available to Smack access rules, which are expanded from "rwxa" to "rwxat". If a file is created in a directory marked as transmutable and if access was granted to perform the operation by a rule that included the transmute mode, then the file gets the Smack label of the directory instead of the Smack label of the creating process. Note that this is equivalent to creating an empty file at the label of the directory and then having the other process write to it. The transmute scheme requires that both the access rule allows transmutation and that the directory be explicitly marked. Signed-off-by: Jarkko Sakkinen Signed-off-by: Casey Schaufler

This patch adds a new security attribute to Smack called

2010-12-02T14:43:39Z

SMACK64EXEC. It defines label that is used while task is running. Exception: in smack_task_wait() child task is checked for write access to parent task using label inherited from the task that forked it. Fixed issues from previous submit: - SMACK64EXEC was not read when SMACK64 was not set. - inode security blob was not updated after setting SMACK64EXEC - inode security blob was not updated when removing SMACK64EXEC