From: David Howells <dhowells@redhat.com> To: linux-cachefs@redhat.com Cc: dhowells@redhat.com, Trond Myklebust <trondmy@hammerspace.com>, Anna Schumaker <anna.schumaker@netapp.com>, Steve French <sfrench@samba.org>, Dominique Martinet <asmadeus@codewreck.org>, Jeff Layton <jlayton@kernel.org>, Matthew Wilcox <willy@infradead.org>, Alexander Viro <viro@zeniv.linux.org.uk>, Omar Sandoval <osandov@osandov.com>, Linus Torvalds <torvalds@linux-foundation.org>, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 35/64] cachefiles: Add security derivation Date: Mon, 29 Nov 2021 14:31:14 +0000 [thread overview] Message-ID: <163819627469.215744.3603633690679962985.stgit@warthog.procyon.org.uk> (raw) In-Reply-To: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk> --- fs/cachefiles/Makefile | 3 + fs/cachefiles/internal.h | 20 ++++++++ fs/cachefiles/security.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 134 insertions(+), 1 deletion(-) create mode 100644 fs/cachefiles/security.c diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile index 183fb5f3b8b1..28bbb0d14868 100644 --- a/fs/cachefiles/Makefile +++ b/fs/cachefiles/Makefile @@ -4,7 +4,8 @@ # cachefiles-y := \ - main.o + main.o \ + security.o cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index b2adcb59b4ce..e57ce5ef875c 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -104,6 +104,26 @@ static inline int cachefiles_inject_remove_error(void) return cachefiles_error_injection_state & 2 ? -EIO : 0; } +/* + * security.c + */ +extern int cachefiles_get_security_ID(struct cachefiles_cache *cache); +extern int cachefiles_determine_cache_security(struct cachefiles_cache *cache, + struct dentry *root, + const struct cred **_saved_cred); + +static inline void cachefiles_begin_secure(struct cachefiles_cache *cache, + const struct cred **_saved_cred) +{ + *_saved_cred = override_creds(cache->cache_cred); +} + +static inline void cachefiles_end_secure(struct cachefiles_cache *cache, + const struct cred *saved_cred) +{ + revert_creds(saved_cred); +} + /* * Error handling */ diff --git a/fs/cachefiles/security.c b/fs/cachefiles/security.c new file mode 100644 index 000000000000..fe777164f1d8 --- /dev/null +++ b/fs/cachefiles/security.c @@ -0,0 +1,112 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* CacheFiles security management + * + * Copyright (C) 2007, 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/fs.h> +#include <linux/cred.h> +#include "internal.h" + +/* + * determine the security context within which we access the cache from within + * the kernel + */ +int cachefiles_get_security_ID(struct cachefiles_cache *cache) +{ + struct cred *new; + int ret; + + _enter("{%s}", cache->secctx); + + new = prepare_kernel_cred(current); + if (!new) { + ret = -ENOMEM; + goto error; + } + + if (cache->secctx) { + ret = set_security_override_from_ctx(new, cache->secctx); + if (ret < 0) { + put_cred(new); + pr_err("Security denies permission to nominate security context: error %d\n", + ret); + goto error; + } + } + + cache->cache_cred = new; + ret = 0; +error: + _leave(" = %d", ret); + return ret; +} + +/* + * see if mkdir and create can be performed in the root directory + */ +static int cachefiles_check_cache_dir(struct cachefiles_cache *cache, + struct dentry *root) +{ + int ret; + + ret = security_inode_mkdir(d_backing_inode(root), root, 0); + if (ret < 0) { + pr_err("Security denies permission to make dirs: error %d", + ret); + return ret; + } + + ret = security_inode_create(d_backing_inode(root), root, 0); + if (ret < 0) + pr_err("Security denies permission to create files: error %d", + ret); + + return ret; +} + +/* + * check the security details of the on-disk cache + * - must be called with security override in force + * - must return with a security override in force - even in the case of an + * error + */ +int cachefiles_determine_cache_security(struct cachefiles_cache *cache, + struct dentry *root, + const struct cred **_saved_cred) +{ + struct cred *new; + int ret; + + _enter(""); + + /* duplicate the cache creds for COW (the override is currently in + * force, so we can use prepare_creds() to do this) */ + new = prepare_creds(); + if (!new) + return -ENOMEM; + + cachefiles_end_secure(cache, *_saved_cred); + + /* use the cache root dir's security context as the basis with + * which create files */ + ret = set_create_files_as(new, d_backing_inode(root)); + if (ret < 0) { + abort_creds(new); + cachefiles_begin_secure(cache, _saved_cred); + _leave(" = %d [cfa]", ret); + return ret; + } + + put_cred(cache->cache_cred); + cache->cache_cred = new; + + cachefiles_begin_secure(cache, _saved_cred); + ret = cachefiles_check_cache_dir(cache, root); + + if (ret == -EOPNOTSUPP) + ret = 0; + _leave(" = %d", ret); + return ret; +}
next prev parent reply other threads:[~2021-11-29 14:33 UTC|newest] Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-11-29 14:22 [PATCH 00/64] fscache, cachefiles: Rewrite David Howells 2021-11-29 14:22 ` [PATCH 01/64] fscache, cachefiles: Disable configuration David Howells 2021-11-29 14:22 ` [PATCH 02/64] cachefiles: Delete the cachefiles driver pending rewrite David Howells 2021-11-29 14:23 ` [PATCH 03/64] fscache: Remove the contents of the fscache driver, " David Howells 2021-11-29 14:23 ` [PATCH 04/64] netfs: Display the netfs inode number in the netfs_read tracepoint David Howells 2021-11-29 14:23 ` [PATCH 05/64] netfs: Pass a flag to ->prepare_write() to say if there's no alloc'd space David Howells 2021-11-29 14:24 ` [PATCH 06/64] fscache: Introduce new driver David Howells 2021-11-29 14:24 ` [PATCH 07/64] fscache: Implement a hash function David Howells 2021-11-29 14:24 ` [PATCH 08/64] fscache: Implement cache registration David Howells 2021-11-29 14:24 ` [PATCH 09/64] fscache: Implement volume registration David Howells 2021-11-29 14:25 ` [PATCH 10/64] fscache: Implement cookie registration David Howells 2021-11-29 14:25 ` [PATCH 11/64] fscache: Implement cache-level access helpers David Howells 2021-11-29 14:25 ` [PATCH 12/64] fscache: Implement volume-level " David Howells 2021-11-29 14:25 ` [PATCH 13/64] fscache: Implement cookie-level " David Howells 2021-11-29 14:26 ` [PATCH 14/64] fscache: Implement functions add/remove a cache David Howells 2021-11-29 14:26 ` [PATCH 15/64] fscache: Provide and use cache methods to lookup/create/free a volume David Howells 2021-11-29 14:26 ` [PATCH 16/64] fscache: Add a function for a cache backend to note an I/O error David Howells 2021-11-29 14:26 ` [PATCH 17/64] fscache: Implement simple cookie state machine David Howells 2021-11-29 14:26 ` [PATCH 18/64] fscache: Implement cookie user counting and resource pinning David Howells 2021-11-29 14:27 ` [PATCH 19/64] fscache: Implement cookie invalidation David Howells 2021-11-29 14:27 ` [PATCH 20/64] fscache: Provide a means to begin an operation David Howells 2021-11-29 14:28 ` [PATCH 21/64] fscache: Count data storage objects in a cache David Howells 2021-11-29 14:28 ` [PATCH 22/64] fscache: Provide read/write stat counters for the cache David Howells 2021-11-29 14:28 ` [PATCH 23/64] fscache: Provide a function to let the netfs update its coherency data David Howells 2021-11-29 14:28 ` [PATCH 24/64] netfs: Pass more information on how to deal with a hole in the cache David Howells 2021-12-06 11:42 ` JeffleXu 2021-12-09 16:49 ` David Howells 2021-11-29 14:28 ` [PATCH 25/64] fscache: Implement raw I/O interface David Howells 2021-11-29 14:29 ` [PATCH 26/64] fscache: Implement higher-level write " David Howells 2021-11-29 14:29 ` [PATCH 27/64] vfs, fscache: Implement pinning of cache usage for writeback David Howells 2021-11-29 14:29 ` [PATCH 28/64] fscache: Provide a function to note the release of a page David Howells 2021-11-29 14:30 ` [PATCH 29/64] fscache: Provide a function to resize a cookie David Howells 2021-11-29 14:30 ` [PATCH 30/64] cachefiles: Introduce rewritten driver David Howells 2021-11-29 14:30 ` [PATCH 31/64] cachefiles: Define structs David Howells 2021-11-29 14:30 ` [PATCH 32/64] cachefiles: Add some error injection support David Howells 2021-11-29 14:30 ` [PATCH 33/64] cachefiles: Add a couple of tracepoints for logging errors David Howells 2021-11-29 14:31 ` [PATCH 34/64] cachefiles: Add cache error reporting macro David Howells 2021-11-29 14:31 ` David Howells [this message] 2021-11-29 14:31 ` [PATCH 36/64] cachefiles: Register a miscdev and parse commands over it David Howells 2021-11-29 14:31 ` [PATCH 37/64] cachefiles: Provide a function to check how much space there is David Howells 2021-11-29 14:31 ` [PATCH 38/64] vfs, cachefiles: Mark a backing file in use with an inode flag David Howells 2021-11-29 14:31 ` [PATCH 39/64] cachefiles: Implement a function to get/create a directory in the cache David Howells 2021-11-29 14:32 ` [PATCH 40/64] cachefiles: Implement cache registration and withdrawal David Howells 2021-11-29 14:32 ` [PATCH 41/64] cachefiles: Implement volume support David Howells 2021-11-29 14:33 ` [PATCH 42/64] cachefiles: Add tracepoints for calls to the VFS David Howells 2021-11-29 14:33 ` [PATCH 43/64] cachefiles: Implement object lifecycle funcs David Howells 2021-11-29 14:33 ` [PATCH 44/64] cachefiles: Implement key to filename encoding David Howells 2021-12-01 5:46 ` JeffleXu 2021-12-01 8:29 ` David Howells 2021-11-29 14:33 ` [PATCH 45/64] cachefiles: Implement metadata/coherency data storage in xattrs David Howells 2021-11-29 14:33 ` [PATCH 46/64] cachefiles: Mark a backing file in use with an inode flag David Howells 2021-11-29 14:33 ` [PATCH 47/64] cachefiles: Implement culling daemon commands David Howells 2021-11-29 14:34 ` [PATCH 48/64] cachefiles: Implement backing file wrangling David Howells 2021-11-29 14:34 ` [PATCH 49/64] cachefiles: Implement begin and end I/O operation David Howells 2021-11-29 14:34 ` [PATCH 50/64] cachefiles: Implement cookie resize for truncate David Howells 2021-11-29 14:34 ` [PATCH 51/64] cachefiles: Implement the I/O routines David Howells 2021-11-30 16:15 ` Nathan Chancellor 2021-11-30 21:05 ` David Howells 2021-11-29 14:34 ` [PATCH 52/64] cachefiles: Allow cachefiles to actually function David Howells 2021-11-29 14:35 ` [PATCH 53/64] fscache, cachefiles: Display stats of no-space events David Howells 2021-11-29 14:35 ` [PATCH 54/64] fscache, cachefiles: Display stat of culling events David Howells 2021-11-29 14:36 ` [PATCH 55/64] afs: Handle len being extending over page end in write_begin/write_end David Howells 2021-11-29 14:36 ` [PATCH 56/64] afs: Fix afs_write_end() to handle len > page size David Howells 2021-11-29 14:36 ` [PATCH 57/64] afs: Convert afs to use the new fscache API David Howells 2021-11-29 14:37 ` [PATCH 58/64] afs: Copy local writes to the cache when writing to the server David Howells 2021-11-29 14:37 ` [PATCH 59/64] afs: Skip truncation on the server of data we haven't written yet David Howells 2021-11-29 14:37 ` [PATCH 60/64] 9p: Use fscache indexing rewrite and reenable caching David Howells 2021-11-29 14:37 ` [PATCH 61/64] 9p: Copy local writes to the cache when writing to the server David Howells 2021-11-29 14:38 ` [PATCH 62/64] nfs: Convert to new fscache volume/cookie API David Howells 2021-11-29 14:38 ` [PATCH 63/64] cifs: Support fscache indexing rewrite (untested) David Howells 2021-11-29 14:38 ` [PATCH 64/64] fscache: Rewrite documentation David Howells 2021-11-29 18:12 ` [PATCH 00/64] fscache, cachefiles: Rewrite Linus Torvalds 2021-11-29 21:40 ` [PATCH 35/64] cachefiles: Add security derivation David Howells
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