user/sven/linux.git/security, branch v4.4.29

ima: use file_dentry()

2016-10-16T15:36:15Z

commit e71b9dff0634edb127f449e076e883ef24a8c76c upstream. Ima tries to call ->setxattr() on overlayfs dentry after having locked underlying inode, which results in a deadlock. Reported-by: Krisztian Litkey Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay") Signed-off-by: Miklos Szeredi Cc: Mimi Zohar Signed-off-by: Greg Kroah-Hartman

apparmor: fix ref count leak when profile sha1 hash is read

2016-08-16T07:30:49Z

commit 0b938a2e2cf0b0a2c8bac9769111545aff0fee97 upstream. Signed-off-by: John Johansen Acked-by: Seth Arnold Signed-off-by: Greg Kroah-Hartman

KEYS: potential uninitialized variable

2016-07-27T16:47:31Z

commit 38327424b40bcebe2de92d07312c89360ac9229a upstream. If __key_link_begin() failed then "edit" would be uninitialized. I've added a check to fix that. This allows a random user to crash the kernel, though it's quite difficult to achieve. There are three ways it can be done as the user would have to cause an error to occur in __key_link(): (1) Cause the kernel to run out of memory. In practice, this is difficult to achieve without ENOMEM cropping up elsewhere and aborting the attempt. (2) Revoke the destination keyring between the keyring ID being looked up and it being tested for revocation. In practice, this is difficult to time correctly because the KEYCTL_REJECT function can only be used from the request-key upcall process. Further, users can only make use of what's in /sbin/request-key.conf, though this does including a rejection debugging test - which means that the destination keyring has to be the caller's session keyring in practice. (3) Have just enough key quota available to create a key, a new session keyring for the upcall and a link in the session keyring, but not then sufficient quota to create a link in the nominated destination keyring so that it fails with EDQUOT. The bug can be triggered using option (3) above using something like the following: echo 80 >/proc/sys/kernel/keys/root_maxbytes keyctl request2 user debug:fred negate @t The above sets the quota to something much lower (80) to make the bug easier to trigger, but this is dependent on the system. Note also that the name of the keyring created contains a random number that may be between 1 and 10 characters in size, so may throw the test off by changing the amount of quota used. Assuming the failure occurs, something like the following will be seen: kfree_debugcheck: out of range ptr 6b6b6b6b6b6b6b68h ------------[ cut here ]------------ kernel BUG at ../mm/slab.c:2821! ... RIP: 0010:[] kfree_debugcheck+0x20/0x25 RSP: 0018:ffff8804014a7de8 EFLAGS: 00010092 RAX: 0000000000000034 RBX: 6b6b6b6b6b6b6b68 RCX: 0000000000000000 RDX: 0000000000040001 RSI: 00000000000000f6 RDI: 0000000000000300 RBP: ffff8804014a7df0 R08: 0000000000000001 R09: 0000000000000000 R10: ffff8804014a7e68 R11: 0000000000000054 R12: 0000000000000202 R13: ffffffff81318a66 R14: 0000000000000000 R15: 0000000000000001 ... Call Trace: kfree+0xde/0x1bc assoc_array_cancel_edit+0x1f/0x36 __key_link_end+0x55/0x63 key_reject_and_link+0x124/0x155 keyctl_reject_key+0xb6/0xe0 keyctl_negate_key+0x10/0x12 SyS_keyctl+0x9f/0xe7 do_syscall_64+0x63/0x13a entry_SYSCALL64_slow_path+0x25/0x25 Fixes: f70e2e06196a ('KEYS: Do preallocation for __key_link()') Signed-off-by: Dan Carpenter Signed-off-by: David Howells Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

security: let security modules use PTRACE_MODE_* with bitmasks

2016-03-03T23:07:32Z

commit 3dfb7d8cdbc7ea0c2970450e60818bb3eefbad69 upstream. It looks like smack and yama weren't aware that the ptrace mode can have flags ORed into it - PTRACE_MODE_NOAUDIT until now, but only for /proc/$pid/stat, and with the PTRACE_MODE_*CREDS patch, all modes have flags ORed into them. Signed-off-by: Jann Horn Acked-by: Kees Cook Acked-by: Casey Schaufler Cc: Oleg Nesterov Cc: Ingo Molnar Cc: James Morris Cc: "Serge E. Hallyn" Cc: Andy Shevchenko Cc: Andy Lutomirski Cc: Al Viro Cc: "Eric W. Biederman" Cc: Willy Tarreau Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

ptrace: use fsuid, fsgid, effective creds for fs access checks

2016-02-25T20:01:16Z

commit caaee6234d05a58c5b4d05e7bf766131b810a657 upstream. By checking the effective credentials instead of the real UID / permitted capabilities, ensure that the calling process actually intended to use its credentials. To ensure that all ptrace checks use the correct caller credentials (e.g. in case out-of-tree code or newly added code omits the PTRACE_MODE_*CREDS flag), use two new flags and require one of them to be set. The problem was that when a privileged task had temporarily dropped its privileges, e.g. by calling setreuid(0, user_uid), with the intent to perform following syscalls with the credentials of a user, it still passed ptrace access checks that the user would not be able to pass. While an attacker should not be able to convince the privileged task to perform a ptrace() syscall, this is a problem because the ptrace access check is reused for things in procfs. In particular, the following somewhat interesting procfs entries only rely on ptrace access checks: /proc/$pid/stat - uses the check for determining whether pointers should be visible, useful for bypassing ASLR /proc/$pid/maps - also useful for bypassing ASLR /proc/$pid/cwd - useful for gaining access to restricted directories that contain files with lax permissions, e.g. in this scenario: lrwxrwxrwx root root /proc/13020/cwd -> /root/foobar drwx------ root root /root drwxr-xr-x root root /root/foobar -rw-r--r-- root root /root/foobar/secret Therefore, on a system where a root-owned mode 6755 binary changes its effective credentials as described and then dumps a user-specified file, this could be used by an attacker to reveal the memory layout of root's processes or reveal the contents of files he is not allowed to access (through /proc/$pid/cwd). [akpm@linux-foundation.org: fix warning] Signed-off-by: Jann Horn Acked-by: Kees Cook Cc: Casey Schaufler Cc: Oleg Nesterov Cc: Ingo Molnar Cc: James Morris Cc: "Serge E. Hallyn" Cc: Andy Shevchenko Cc: Andy Lutomirski Cc: Al Viro Cc: "Eric W. Biederman" Cc: Willy Tarreau Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

EVM: Use crypto_memneq() for digest comparisons

2016-02-17T20:31:04Z

commit 613317bd212c585c20796c10afe5daaa95d4b0a1 upstream. This patch fixes vulnerability CVE-2016-2085. The problem exists because the vm_verify_hmac() function includes a use of memcmp(). Unfortunately, this allows timing side channel attacks; specifically a MAC forgery complexity drop from 2^128 to 2^12. This patch changes the memcmp() to the cryptographically safe crypto_memneq(). Reported-by: Xiaofei Rex Guo Signed-off-by: Ryan Ware Signed-off-by: Mimi Zohar Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman

KEYS: Fix keyring ref leak in join_session_keyring()

2016-01-31T19:28:53Z

commit 23567fd052a9abb6d67fe8e7a9ccdd9800a540f2 upstream. This fixes CVE-2016-0728. If a thread is asked to join as a session keyring the keyring that's already set as its session, we leak a keyring reference. This can be tested with the following program: #include #include #include #include int main(int argc, const char *argv[]) { int i = 0; key_serial_t serial; serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING, "leaked-keyring"); if (serial < 0) { perror("keyctl"); return -1; } if (keyctl(KEYCTL_SETPERM, serial, KEY_POS_ALL | KEY_USR_ALL) < 0) { perror("keyctl"); return -1; } for (i = 0; i < 100; i++) { serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING, "leaked-keyring"); if (serial < 0) { perror("keyctl"); return -1; } } return 0; } If, after the program has run, there something like the following line in /proc/keys: 3f3d898f I--Q--- 100 perm 3f3f0000 0 0 keyring leaked-keyring: empty with a usage count of 100 * the number of times the program has been run, then the kernel is malfunctioning. If leaked-keyring has zero usages or has been garbage collected, then the problem is fixed. Reported-by: Yevgeny Pats Signed-off-by: David Howells Acked-by: Don Zickus Acked-by: Prarit Bhargava Acked-by: Jarod Wilson Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman

KEYS: Fix race between read and revoke

2015-12-19T01:34:43Z

This fixes CVE-2015-7550. There's a race between keyctl_read() and keyctl_revoke(). If the revoke happens between keyctl_read() checking the validity of a key and the key's semaphore being taken, then the key type read method will see a revoked key. This causes a problem for the user-defined key type because it assumes in its read method that there will always be a payload in a non-revoked key and doesn't check for a NULL pointer. Fix this by making keyctl_read() check the validity of a key after taking semaphore instead of before. I think the bug was introduced with the original keyrings code. This was discovered by a multithreaded test program generated by syzkaller (http://github.com/google/syzkaller). Here's a cleaned up version: #include #include #include void *thr0(void *arg) { key_serial_t key = (unsigned long)arg; keyctl_revoke(key); return 0; } void *thr1(void *arg) { key_serial_t key = (unsigned long)arg; char buffer[16]; keyctl_read(key, buffer, 16); return 0; } int main() { key_serial_t key = add_key("user", "%", "foo", 3, KEY_SPEC_USER_KEYRING); pthread_t th[5]; pthread_create(&th[0], 0, thr0, (void *)(unsigned long)key); pthread_create(&th[1], 0, thr1, (void *)(unsigned long)key); pthread_create(&th[2], 0, thr0, (void *)(unsigned long)key); pthread_create(&th[3], 0, thr1, (void *)(unsigned long)key); pthread_join(th[0], 0); pthread_join(th[1], 0); pthread_join(th[2], 0); pthread_join(th[3], 0); return 0; } Build as: cc -o keyctl-race keyctl-race.c -lkeyutils -lpthread Run as: while keyctl-race; do :; done as it may need several iterations to crash the kernel. The crash can be summarised as: BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 IP: [] user_read+0x56/0xa3 ... Call Trace: [] keyctl_read_key+0xb6/0xd7 [] SyS_keyctl+0x83/0xe0 [] entry_SYSCALL_64_fastpath+0x12/0x6f Reported-by: Dmitry Vyukov Signed-off-by: David Howells Tested-by: Dmitry Vyukov Cc: stable@vger.kernel.org Signed-off-by: James Morris

Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/selinux into for-linus2

2015-11-26T04:04:19Z

KEYS: Fix handling of stored error in a negatively instantiated user key

2015-11-25T03:19:47Z

If a user key gets negatively instantiated, an error code is cached in the payload area. A negatively instantiated key may be then be positively instantiated by updating it with valid data. However, the ->update key type method must be aware that the error code may be there. The following may be used to trigger the bug in the user key type: keyctl request2 user user "" @u keyctl add user user "a" @u which manifests itself as: BUG: unable to handle kernel paging request at 00000000ffffff8a IP: [] __call_rcu.constprop.76+0x1f/0x280 kernel/rcu/tree.c:3046 PGD 7cc30067 PUD 0 Oops: 0002 [#1] SMP Modules linked in: CPU: 3 PID: 2644 Comm: a.out Not tainted 4.3.0+ #49 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88003ddea700 ti: ffff88003dd88000 task.ti: ffff88003dd88000 RIP: 0010:[] [] __call_rcu.constprop.76+0x1f/0x280 [] __call_rcu.constprop.76+0x1f/0x280 kernel/rcu/tree.c:3046 RSP: 0018:ffff88003dd8bdb0 EFLAGS: 00010246 RAX: 00000000ffffff82 RBX: 0000000000000000 RCX: 0000000000000001 RDX: ffffffff81e3fe40 RSI: 0000000000000000 RDI: 00000000ffffff82 RBP: ffff88003dd8bde0 R08: ffff88007d2d2da0 R09: 0000000000000000 R10: 0000000000000000 R11: ffff88003e8073c0 R12: 00000000ffffff82 R13: ffff88003dd8be68 R14: ffff88007d027600 R15: ffff88003ddea700 FS: 0000000000b92880(0063) GS:ffff88007fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000ffffff8a CR3: 000000007cc5f000 CR4: 00000000000006e0 Stack: ffff88003dd8bdf0 ffffffff81160a8a 0000000000000000 00000000ffffff82 ffff88003dd8be68 ffff88007d027600 ffff88003dd8bdf0 ffffffff810a39e5 ffff88003dd8be20 ffffffff812a31ab ffff88007d027600 ffff88007d027620 Call Trace: [] kfree_call_rcu+0x15/0x20 kernel/rcu/tree.c:3136 [] user_update+0x8b/0xb0 security/keys/user_defined.c:129 [< inline >] __key_update security/keys/key.c:730 [] key_create_or_update+0x291/0x440 security/keys/key.c:908 [< inline >] SYSC_add_key security/keys/keyctl.c:125 [] SyS_add_key+0x101/0x1e0 security/keys/keyctl.c:60 [] entry_SYSCALL_64_fastpath+0x12/0x6a arch/x86/entry/entry_64.S:185 Note the error code (-ENOKEY) in EDX. A similar bug can be tripped by: keyctl request2 trusted user "" @u keyctl add trusted user "a" @u This should also affect encrypted keys - but that has to be correctly parameterised or it will fail with EINVAL before getting to the bit that will crashes. Reported-by: Dmitry Vyukov Signed-off-by: David Howells Acked-by: Mimi Zohar Signed-off-by: James Morris