linux/security/keys/proc.c, branch v4.9

KEYS: Fix short sprintf buffer in /proc/keys show function

2016-10-27T05:03:24Z

This fixes CVE-2016-7042. Fix a short sprintf buffer in proc_keys_show(). If the gcc stack protector is turned on, this can cause a panic due to stack corruption. The problem is that xbuf[] is not big enough to hold a 64-bit timeout rendered as weeks: (gdb) p 0xffffffffffffffffULL/(60*60*24*7) $2 = 30500568904943 That's 14 chars plus NUL, not 11 chars plus NUL. Expand the buffer to 16 chars. I think the unpatched code apparently works if the stack-protector is not enabled because on a 32-bit machine the buffer won't be overflowed and on a 64-bit machine there's a 64-bit aligned pointer at one side and an int that isn't checked again on the other side. The panic incurred looks something like: Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: ffffffff81352ebe CPU: 0 PID: 1692 Comm: reproducer Not tainted 4.7.2-201.fc24.x86_64 #1 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 0000000000000086 00000000fbbd2679 ffff8800a044bc00 ffffffff813d941f ffffffff81a28d58 ffff8800a044bc98 ffff8800a044bc88 ffffffff811b2cb6 ffff880000000010 ffff8800a044bc98 ffff8800a044bc30 00000000fbbd2679 Call Trace: [] dump_stack+0x63/0x84 [] panic+0xde/0x22a [] ? proc_keys_show+0x3ce/0x3d0 [] __stack_chk_fail+0x19/0x30 [] proc_keys_show+0x3ce/0x3d0 [] ? key_validate+0x50/0x50 [] ? key_default_cmp+0x20/0x20 [] seq_read+0x2cc/0x390 [] proc_reg_read+0x42/0x70 [] __vfs_read+0x37/0x150 [] ? security_file_permission+0xa0/0xc0 [] vfs_read+0x96/0x130 [] SyS_read+0x55/0xc0 [] entry_SYSCALL_64_fastpath+0x1a/0xa4 Reported-by: Ondrej Kozina Signed-off-by: David Howells Tested-by: Ondrej Kozina cc: stable@vger.kernel.org Signed-off-by: James Morris

KEYS: Make /proc/keys unconditional if CONFIG_KEYS=y

2015-01-22T22:34:32Z

Now that /proc/keys is used by libkeyutils to look up a key by type and description, we should make it unconditional and remove CONFIG_DEBUG_PROC_KEYS. Reported-by: Jiri Kosina Signed-off-by: David Howells Tested-by: Jiri Kosina

KEYS: Preparse match data

2014-09-16T16:36:02Z

Preparse the match data. This provides several advantages: (1) The preparser can reject invalid criteria up front. (2) The preparser can convert the criteria to binary data if necessary (the asymmetric key type really wants to do binary comparison of the key IDs). (3) The preparser can set the type of search to be performed. This means that it's not then a one-off setting in the key type. (4) The preparser can set an appropriate comparator function. Signed-off-by: David Howells Acked-by: Vivek Goyal

KEYS: Move the flags representing required permission to linux/key.h

2014-03-14T17:44:49Z

Move the flags representing required permission to linux/key.h as the perm parameter of security_key_permission() is in terms of them - and not the permissions mask flags used in key->perm. Whilst we're at it: (1) Rename them to be KEY_NEED_xxx rather than KEY_xxx to avoid collisions with symbols in uapi/linux/input.h. (2) Don't use key_perm_t for a mask of required permissions, but rather limit it to the permissions mask attached to the key and arguments related directly to that. Signed-off-by: David Howells Tested-by: Dmitry Kasatkin

KEYS: Introduce a search context structure

2013-09-24T09:35:15Z

Search functions pass around a bunch of arguments, each of which gets copied with each call. Introduce a search context structure to hold these. Whilst we're at it, create a search flag that indicates whether the search should be directly to the description or whether it should iterate through all keys looking for a non-description match. This will be useful when keyrings use a generic data struct with generic routines to manage their content as the search terms can just be passed through to the iterator callback function. Also, for future use, the data to be supplied to the match function is separated from the description pointer in the search context. This makes it clear which is being supplied. Signed-off-by: David Howells

userns: Convert security/keys to the new userns infrastructure

2012-09-14T01:28:02Z

- Replace key_user ->user_ns equality checks with kuid_has_mapping checks. - Use from_kuid to generate key descriptions - Use kuid_t and kgid_t and the associated helpers instead of uid_t and gid_t - Avoid potential problems with file descriptor passing by displaying keys in the user namespace of the opener of key status proc files. Cc: linux-security-module@vger.kernel.org Cc: keyrings@linux-nfs.org Cc: David Howells Signed-off-by: Eric W. Biederman

KEYS: Add invalidation support

2012-05-11T09:56:56Z

Add support for invalidating a key - which renders it immediately invisible to further searches and causes the garbage collector to immediately wake up, remove it from keyrings and then destroy it when it's no longer referenced. It's better not to do this with keyctl_revoke() as that marks the key to start returning -EKEYREVOKED to searches when what is actually desired is to have the key refetched. To invalidate a key the caller must be granted SEARCH permission by the key. This may be too strict. It may be better to also permit invalidation if the caller has any of READ, WRITE or SETATTR permission. The primary use for this is to evict keys that are cached in special keyrings, such as the DNS resolver or an ID mapper. Signed-off-by: David Howells

KEYS: Improve /proc/keys

2011-03-17T00:59:32Z

Improve /proc/keys by: (1) Don't attempt to summarise the payload of a negated key. It won't have one. To this end, a helper function - key_is_instantiated() has been added that allows the caller to find out whether the key is positively instantiated (as opposed to being uninstantiated or negatively instantiated). (2) Do show keys that are negative, expired or revoked rather than hiding them. This requires an override flag (no_state_check) to be passed to search_my_process_keyrings() and keyring_search_aux() to suppress this check. Without this, keys that are possessed by the caller, but only grant permissions to the caller if possessed are skipped as the possession check fails. Keys that are visible due to user, group or other checks are visible with or without this patch. Signed-off-by: David Howells Signed-off-by: James Morris

KEYS: Fix up comments in key management code

2011-01-21T22:59:30Z

Fix up comments in the key management code. No functional changes. Signed-off-by: David Howells Signed-off-by: Linus Torvalds

KEYS: Do some style cleanup in the key management code.

2011-01-21T22:59:29Z

Do a bit of a style clean up in the key management code. No functional changes. Done using: perl -p -i -e 's!^/[*]*/\n!!' security/keys/*.c perl -p -i -e 's!} /[*] end [a-z0-9_]*[(][)] [*]/\n!}\n!' security/keys/*.c sed -i -s -e ": next" -e N -e 's/^\n[}]$/}/' -e t -e P -e 's/^.*\n//' -e "b next" security/keys/*.c To remove /*****/ lines, remove comments on the closing brace of a function to name the function and remove blank lines before the closing brace of a function. Signed-off-by: David Howells Signed-off-by: Linus Torvalds