From patchwork Tue Oct 11 14:38:12 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Natty SRU: eCryptfs: Clear ECRYPTFS_NEW_FILE flag during truncate Date: Tue, 11 Oct 2011 04:38:12 -0000 From: Tim Gardner X-Patchwork-Id: 118994 Message-Id: <4E9454D4.5010500@canonical.com> To: Leann Ogasawara Cc: kernel-team@lists.ubuntu.com, Tyler Hicks On 10/11/2011 01:53 PM, Tim Gardner wrote: > On 10/10/2011 04:26 PM, Tyler Hicks wrote: >> On 2011-10-10 07:16:59, Leann Ogasawara wrote: >>> On Mon, 2011-10-10 at 14:46 +0100, Tim Gardner wrote: >>>> On 10/10/2011 02:42 PM, Leann Ogasawara wrote: >>>>> On Sun, 2011-10-09 at 05:12 -0600, Tim Gardner wrote: >>>>>> From 27ed7cb2b00512e81016419715c1d9b6794b06ae Mon Sep 17 00:00:00 >>>>>> 2001 >>>>>> From: Tyler Hicks >>>>>> Date: Fri, 7 Oct 2011 15:54:26 -0500 >>>>>> Subject: [PATCH] eCryptfs: Clear ECRYPTFS_NEW_FILE flag during >>>>>> truncate >>>>>> >>>>>> BugLink: http://bugs.launchpad.net/bugs/745836 >>>>>> >>>>>> The ECRYPTFS_NEW_FILE crypt_stat flag is set upon creation of a new >>>>>> eCryptfs file. When the flag is set, eCryptfs reads directly from the >>>>>> lower filesystem when bringing a page up to date. This means that no >>>>>> offset translation (for the eCryptfs file metadata in the lower file) >>>>>> and no decryption is performed. The flag is cleared just before the >>>>>> first write is completed (at the beginning of >>>>>> ecryptfs_write_begin()). >>>>>> >>>>>> It was discovered that if a new file was created and then extended >>>>>> with >>>>>> truncate, the ECRYPTFS_NEW_FILE flag was not cleared. If pages >>>>>> corresponding to this file are ever reclaimed, any subsequent reads >>>>>> would result in userspace seeing eCryptfs file metadata and encrypted >>>>>> file contents instead of the expected decrypted file contents. >>>>>> >>>>>> Data corruption is possible if the file is written to before the >>>>>> eCryptfs directory is unmounted. The data written will be copied into >>>>>> pages which have been read directly from the lower file rather than >>>>>> zeroed pages, as would be expected after extending the file with >>>>>> truncate. >>>>>> >>>>>> This flag, and the functionality that used it, was removed in >>>>>> upstream >>>>>> kernels in 2.6.39 with the following commits: >>>>>> >>>>>> bd4f0fe8bb7c73c738e1e11bc90d6e2cf9c6e20e >>>>>> fed8859b3ab94274c986cbdf7d27130e0545f02c >>>>> >>>>> Is there a reason we're not just cherry-picking the upstream patches? >>>>> And so I would assume this patch should be marked as SAUCE? >>>>> >>>>> Thanks, >>>>> Leann >>>>> >>>> >>>> Yeah, 'UBUNTU: SAUCE:' for sure. Tyler said in the LP report that >>>> backporting those 2 commits was getting too involved and complicated. >>>> Given the simplicity of his ultimate solution I thought the backport >>>> seemed better. >>> >>> Hrm, those two patches appear to cherry-pick cleanly for me, although I >>> could be missing other external factors. Reading the bug report it >>> sounds like Tyler originally thought this was fixed with upstream commit >>> 3b06b3ebf44170c90c893c6c80916db6e922b9f2 and it was that commit which >>> was problematic to backport (see comment #85). >> >> Yep, I was wrong about 3b06b3eb being the fix. Bad assumption on my >> part. >> >>> It's in the following >>> comment #86 that he identifies the actual fix being commits bd4f0fe8 and >>> fed8859b. >>> >>> Regardless, the SAUCE patch looks fine to me. It's straightforward and >>> tested. I was just more curious as to why we don't just cherry-pick the >>> upstream patches. I've CC'd Tyler to get his reasoning. >> >> While bd4f0fe8 and fed8859b will cherry-pick cleanly and get rid of the >> buggy code, they weren't intended to be bug fixes when I wrote them. >> They were just intended to remove some functionality in order to make >> the file creation process a bit faster. To me, it just didn't feel like >> something that should be backported consider how simple the real fix >> was. >> >> Tyler > > Tyler - these 2 patches are simple enough that I'd prefer the clean > cherry-picks (which we try to use as a matter of policy). I'll retest > and send out the results... > > rtg The attached patches are clean cherry-picks and produce the same result without regression. rtg Acked-by: Stefan Bader Acked-by: Leann Ogasawara >From ebcee101904bc38b029db54af4f56d0570787b5e Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Wed, 23 Feb 2011 00:54:20 -0600 Subject: [PATCH 2/2] eCryptfs: Remove ECRYPTFS_NEW_FILE crypt stat flag Now that grow_file() is not called in the ecryptfs_create() path, the ECRYPTFS_NEW_FILE flag is no longer needed. It helped ecryptfs_readpage() know not to decrypt zeroes that were read from the lower file in the grow_file() path. Signed-off-by: Tyler Hicks (cherry picked from commit fed8859b3ab94274c986cbdf7d27130e0545f02c) Signed-off-by: Tim Gardner --- fs/ecryptfs/ecryptfs_kernel.h | 25 ++++++++++++------------- fs/ecryptfs/inode.c | 1 - fs/ecryptfs/mmap.c | 15 ++------------- 3 files changed, 14 insertions(+), 27 deletions(-) diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h index e007534..427478e 100644 --- a/fs/ecryptfs/ecryptfs_kernel.h +++ b/fs/ecryptfs/ecryptfs_kernel.h @@ -257,19 +257,18 @@ struct ecryptfs_filename { struct ecryptfs_crypt_stat { #define ECRYPTFS_STRUCT_INITIALIZED 0x00000001 #define ECRYPTFS_POLICY_APPLIED 0x00000002 -#define ECRYPTFS_NEW_FILE 0x00000004 -#define ECRYPTFS_ENCRYPTED 0x00000008 -#define ECRYPTFS_SECURITY_WARNING 0x00000010 -#define ECRYPTFS_ENABLE_HMAC 0x00000020 -#define ECRYPTFS_ENCRYPT_IV_PAGES 0x00000040 -#define ECRYPTFS_KEY_VALID 0x00000080 -#define ECRYPTFS_METADATA_IN_XATTR 0x00000100 -#define ECRYPTFS_VIEW_AS_ENCRYPTED 0x00000200 -#define ECRYPTFS_KEY_SET 0x00000400 -#define ECRYPTFS_ENCRYPT_FILENAMES 0x00000800 -#define ECRYPTFS_ENCFN_USE_MOUNT_FNEK 0x00001000 -#define ECRYPTFS_ENCFN_USE_FEK 0x00002000 -#define ECRYPTFS_UNLINK_SIGS 0x00004000 +#define ECRYPTFS_ENCRYPTED 0x00000004 +#define ECRYPTFS_SECURITY_WARNING 0x00000008 +#define ECRYPTFS_ENABLE_HMAC 0x00000010 +#define ECRYPTFS_ENCRYPT_IV_PAGES 0x00000020 +#define ECRYPTFS_KEY_VALID 0x00000040 +#define ECRYPTFS_METADATA_IN_XATTR 0x00000080 +#define ECRYPTFS_VIEW_AS_ENCRYPTED 0x00000100 +#define ECRYPTFS_KEY_SET 0x00000200 +#define ECRYPTFS_ENCRYPT_FILENAMES 0x00000400 +#define ECRYPTFS_ENCFN_USE_MOUNT_FNEK 0x00000800 +#define ECRYPTFS_ENCFN_USE_FEK 0x00001000 +#define ECRYPTFS_UNLINK_SIGS 0x00002000 u32 flags; unsigned int file_version; size_t iv_bytes; diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c index 8fa365a..f99051b 100644 --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -161,7 +161,6 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry) crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); goto out; } - crypt_stat->flags |= ECRYPTFS_NEW_FILE; ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n"); rc = ecryptfs_new_file_context(ecryptfs_dentry); if (rc) { diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c index eb9d967..c52925c 100644 --- a/fs/ecryptfs/mmap.c +++ b/fs/ecryptfs/mmap.c @@ -193,11 +193,7 @@ static int ecryptfs_readpage(struct file *file, struct page *page) &ecryptfs_inode_to_private(page->mapping->host)->crypt_stat; int rc = 0; - if (!crypt_stat - || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED) - || (crypt_stat->flags & ECRYPTFS_NEW_FILE)) { - ecryptfs_printk(KERN_DEBUG, - "Passing through unencrypted page\n"); + if (!crypt_stat || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) { rc = ecryptfs_read_lower_page_segment(page, page->index, 0, PAGE_CACHE_SIZE, page->mapping->host); @@ -295,8 +291,7 @@ static int ecryptfs_write_begin(struct file *file, struct ecryptfs_crypt_stat *crypt_stat = &ecryptfs_inode_to_private(mapping->host)->crypt_stat; - if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED) - || (crypt_stat->flags & ECRYPTFS_NEW_FILE)) { + if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) { rc = ecryptfs_read_lower_page_segment( page, index, 0, PAGE_CACHE_SIZE, mapping->host); if (rc) { @@ -492,12 +487,6 @@ static int ecryptfs_write_end(struct file *file, &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; int rc; - if (crypt_stat->flags & ECRYPTFS_NEW_FILE) { - ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in " - "crypt_stat at memory location [%p]\n", crypt_stat); - crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE); - } else - ecryptfs_printk(KERN_DEBUG, "Not a new file\n"); ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page" "(page w/ index = [0x%.16lx], to = [%d])\n", index, to); if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) { -- 1.7.1