lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <5F32BA3E.90801@cn.fujitsu.com> Date: Tue, 11 Aug 2020 23:33:18 +0800 From: Xiao Yang <yangx.jy@...fujitsu.com> To: Ira Weiny <ira.weiny@...el.com> CC: <darrick.wong@...cle.com>, <tytso@....edu>, <ebiggers@...nel.org>, <linux-ext4@...r.kernel.org> Subject: Re: [PATCH v2] chattr/lsattr: Support dax attribute On 2020/8/8 0:03, Ira Weiny wrote: > On Tue, Jul 28, 2020 at 01:33:21PM +0800, Xiao Yang wrote: >> Use the letter 'x' to set/get dax attribute on a directory/file. >> >> Signed-off-by: Xiao Yang<yangx.jy@...fujitsu.com> >> --- >> >> V1->V2: >> 1) Define FS_DAX_FL in order and add missing 'x' letter in manpage. >> 2) Add more detailed description about 'x' attribute. >> 3) 'x' is a separate attribute and doesn't always affect S_DAX(i.e. >> pagecache bypass) so remove the related info. >> >> lib/e2p/pf.c | 1 + >> lib/ext2fs/ext2_fs.h | 1 + >> misc/chattr.1.in | 15 ++++++++++++--- >> misc/chattr.c | 3 ++- >> 4 files changed, 16 insertions(+), 4 deletions(-) >> >> diff --git a/lib/e2p/pf.c b/lib/e2p/pf.c >> index 0c6998c4..e59cccff 100644 >> --- a/lib/e2p/pf.c >> +++ b/lib/e2p/pf.c >> @@ -44,6 +44,7 @@ static struct flags_name flags_array[] = { >> { EXT2_TOPDIR_FL, "T", "Top_of_Directory_Hierarchies" }, >> { EXT4_EXTENTS_FL, "e", "Extents" }, >> { FS_NOCOW_FL, "C", "No_COW" }, >> + { FS_DAX_FL, "x", "Dax" }, >> { EXT4_CASEFOLD_FL, "F", "Casefold" }, >> { EXT4_INLINE_DATA_FL, "N", "Inline_Data" }, >> { EXT4_PROJINHERIT_FL, "P", "Project_Hierarchy" }, >> diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h >> index 6c20ea77..88f510a3 100644 >> --- a/lib/ext2fs/ext2_fs.h >> +++ b/lib/ext2fs/ext2_fs.h >> @@ -335,6 +335,7 @@ struct ext2_dx_tail { >> /* EXT4_EOFBLOCKS_FL 0x00400000 was here */ >> #define FS_NOCOW_FL 0x00800000 /* Do not cow file */ >> #define EXT4_SNAPFILE_FL 0x01000000 /* Inode is a snapshot */ >> +#define FS_DAX_FL 0x02000000 /* Inode is DAX */ > Per-file support is not supported on ext2... > > So I'm suspicious of this change. It is probably not an issue but I just > wanted to check if you are trying to test on ext2? Hi Ira, Thanks for your reply. :-) chattr failed to set the 'x' flag on ext2 sliently because ext2_ioctl() in kernel drops unsupported 'FS_DAX_FL' sliently: ---------------------------------------------- # touch file # chattr +x file;echo $? 0 # lsattr file --------------------- file ---------------------------------------------- ext2_ioctl() drops all unsupported flags sliently(see the following code) so I am not sure if we should return -EOPNOTSUPP for the unsupported FS_DAX_FL: ---------------------------------------------- long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) ... case EXT2_IOC_SETFLAGS: { ... flags = flags & EXT2_FL_USER_MODIFIABLE; flags |= oldflags & ~EXT2_FL_USER_MODIFIABLE; ei->i_flags = flags; ext2_set_inode_flags(inode); ... ---------------------------------------------- Best Regards, Xiao Yang > Ira > >> #define EXT4_SNAPFILE_DELETED_FL 0x04000000 /* Snapshot is being deleted */ >> #define EXT4_SNAPFILE_SHRUNK_FL 0x08000000 /* Snapshot shrink has completed */ >> #define EXT4_INLINE_DATA_FL 0x10000000 /* Inode has inline data */ >> diff --git a/misc/chattr.1.in b/misc/chattr.1.in >> index ff2fcf00..5a4928a5 100644 >> --- a/misc/chattr.1.in >> +++ b/misc/chattr.1.in >> @@ -23,13 +23,13 @@ chattr \- change file attributes on a Linux file system >> .B chattr >> changes the file attributes on a Linux file system. >> .PP >> -The format of a symbolic mode is +-=[aAcCdDeFijPsStTu]. >> +The format of a symbolic mode is +-=[aAcCdDeFijPsStTux]. >> .PP >> The operator '+' causes the selected attributes to be added to the >> existing attributes of the files; '-' causes them to be removed; and '=' >> causes them to be the only attributes that the files have. >> .PP >> -The letters 'aAcCdDeFijPsStTu' select the new attributes for the files: >> +The letters 'aAcCdDeFijPsStTux' select the new attributes for the files: >> append only (a), >> no atime updates (A), >> compressed (c), >> @@ -45,7 +45,8 @@ secure deletion (s), >> synchronous updates (S), >> no tail-merging (t), >> top of directory hierarchy (T), >> -and undeletable (u). >> +undeletable (u), >> +and direct access for files (x). >> .PP >> The following attributes are read-only, and may be listed by >> .BR lsattr (1) >> @@ -210,6 +211,14 @@ saved. This allows the user to ask for its undeletion. Note: please >> make sure to read the bugs and limitations section at the end of this >> document. >> .TP >> +.B x >> +The 'x' attribute can be set on a directory or file. If the attribute >> +is set on an existing directory, it will be inherited by all files and >> +subdirectories that are subsequently created in the directory. If an >> +existing directory has contained some files and subdirectories, modifying >> +the attribute on the parent directory doesn't change the attributes on >> +these files and subdirectories. >> +.TP >> .B V >> A file with the 'V' attribute set has fs-verity enabled. It cannot be >> written to, and the filesystem will automatically verify all data read >> diff --git a/misc/chattr.c b/misc/chattr.c >> index a5d60170..c0337f86 100644 >> --- a/misc/chattr.c >> +++ b/misc/chattr.c >> @@ -86,7 +86,7 @@ static unsigned long sf; >> static void usage(void) >> { >> fprintf(stderr, >> - _("Usage: %s [-pRVf] [-+=aAcCdDeijPsStTuF] [-v version] files...\n"), >> + _("Usage: %s [-pRVf] [-+=aAcCdDeijPsStTuFx] [-v version] files...\n"), >> program_name); >> exit(1); >> } >> @@ -112,6 +112,7 @@ static const struct flags_char flags_array[] = { >> { EXT2_NOTAIL_FL, 't' }, >> { EXT2_TOPDIR_FL, 'T' }, >> { FS_NOCOW_FL, 'C' }, >> + { FS_DAX_FL, 'x' }, >> { EXT4_CASEFOLD_FL, 'F' }, >> { 0, 0 } >> }; >> -- >> 2.21.0 >> >> >> > > . >
Powered by blists - more mailing lists