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2012-05-22Merge branch 'master' of git://git.infradead.org/users/eparis/selinux into nextJames Morris
Per pull request, for 3.5.
2012-05-14Smack: allow for significantly longer Smack labels v4Casey Schaufler
V4 updated to current linux-security#next Targeted for git://gitorious.org/smack-next/kernel.git Modern application runtime environments like to use naming schemes that are structured and generated without human intervention. Even though the Smack limit of 23 characters for a label name is perfectly rational for human use there have been complaints that the limit is a problem in environments where names are composed from a set or sources, including vendor, author, distribution channel and application name. Names like softwarehouse-pgwodehouse-coolappstore-mellowmuskrats are becoming harder to avoid. This patch introduces long label support in Smack. Labels are now limited to 255 characters instead of the old 23. The primary reason for limiting the labels to 23 characters was so they could be directly contained in CIPSO category sets. This is still done were possible, but for labels that are too large a mapping is required. This is perfectly safe for communication that stays "on the box" and doesn't require much coordination between boxes beyond what would have been required to keep label names consistent. The bulk of this patch is in smackfs, adding and updating administrative interfaces. Because existing APIs can't be changed new ones that do much the same things as old ones have been introduced. The Smack specific CIPSO data representation has been removed and replaced with the data format used by netlabel. The CIPSO header is now computed when a label is imported rather than on use. This results in improved IP performance. The smack label is now allocated separately from the containing structure, allowing for larger strings. Four new /smack interfaces have been introduced as four of the old interfaces strictly required labels be specified in fixed length arrays. The access interface is supplemented with the check interface: access "Subject Object rwxat" access2 "Subject Object rwaxt" The load interface is supplemented with the rules interface: load "Subject Object rwxat" load2 "Subject Object rwaxt" The load-self interface is supplemented with the self-rules interface: load-self "Subject Object rwxat" load-self2 "Subject Object rwaxt" The cipso interface is supplemented with the wire interface: cipso "Subject lvl cnt c1 c2 ..." cipso2 "Subject lvl cnt c1 c2 ..." The old interfaces are maintained for compatibility. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2012-05-14gfp flags for security_inode_alloc()?Tetsuo Handa
Dave Chinner wrote: > Yes, because you have no idea what the calling context is except > for the fact that is from somewhere inside filesystem code and the > filesystem could be holding locks. Therefore, GFP_NOFS is really the > only really safe way to allocate memory here. I see. Thank you. I'm not sure, but can call trace happen where somewhere inside network filesystem or stackable filesystem code with locks held invokes operations that involves GFP_KENREL memory allocation outside that filesystem? ---------- [PATCH] SMACK: Fix incorrect GFP_KERNEL usage. new_inode_smack() which can be called from smack_inode_alloc_security() needs to use GFP_NOFS like SELinux's inode_alloc_security() does, for security_inode_alloc() is called from inode_init_always() and inode_init_always() is called from xfs_inode_alloc() which is using GFP_NOFS. smack_inode_init_security() needs to use GFP_NOFS like selinux_inode_init_security() does, for initxattrs() callback function (e.g. btrfs_initxattrs()) which is called from security_inode_init_security() is using GFP_NOFS. smack_audit_rule_match() needs to use GFP_ATOMIC, for security_audit_rule_match() can be called from audit_filter_user_rules() and audit_filter_user_rules() is called from audit_filter_user() with RCU read lock held. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Casey Schaufler <cschaufler@cschaufler-intel.(none)>
2012-05-14Smack: recursive tramsmuteCasey Schaufler
The transmuting directory feature of Smack requires that the transmuting attribute be explicitly set in all cases. It seems the users of this facility would expect that the transmuting attribute be inherited by subdirectories that are created in a transmuting directory. This does not seem to add any additional complexity to the understanding of how the system works. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2012-04-18Smack: move label list initializationCasey Schaufler
A kernel with Smack enabled will fail if tmpfs has xattr support. Move the initialization of predefined Smack label list entries to the LSM initialization from the smackfs setup. This became an issue when tmpfs acquired xattr support, but was never correct. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-04-10Smack: build when CONFIG_AUDIT not definedKees Cook
This fixes builds where CONFIG_AUDIT is not defined and CONFIG_SECURITY_SMACK=y. This got introduced by the stack-usage reducation commit 48c62af68a40 ("LSM: shrink the common_audit_data data union"). Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Eric Paris <eparis@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-04-09LSM: do not initialize common_audit_data to 0Eric Paris
It isn't needed. If you don't set the type of the data associated with that type it is a pretty obvious programming bug. So why waste the cycles? Signed-off-by: Eric Paris <eparis@redhat.com>
2012-04-09SELinux: rename dentry_open to file_openEric Paris
dentry_open takes a file, rename it to file_open Signed-off-by: Eric Paris <eparis@redhat.com>
2012-04-03lsm_audit: don't specify the audit pre/post callbacks in 'struct ↵Linus Torvalds
common_audit_data' It just bloats the audit data structure for no good reason, since the only time those fields are filled are just before calling the common_lsm_audit() function, which is also the only user of those fields. So just make them be the arguments to common_lsm_audit(), rather than bloating that structure that is passed around everywhere, and is initialized in hot paths. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-04-03LSM: shrink the common_audit_data data unionEric Paris
After shrinking the common_audit_data stack usage for private LSM data I'm not going to shrink the data union. To do this I'm going to move anything larger than 2 void * ptrs to it's own structure and require it to be declared separately on the calling stack. Thus hot paths which don't need more than a couple pointer don't have to declare space to hold large unneeded structures. I could get this down to one void * by dealing with the key struct and the struct path. We'll see if that is helpful after taking care of networking. Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-04-03LSM: shrink sizeof LSM specific portion of common_audit_dataEric Paris
Linus found that the gigantic size of the common audit data caused a big perf hit on something as simple as running stat() in a loop. This patch requires LSMs to declare the LSM specific portion separately rather than doing it in a union. Thus each LSM can be responsible for shrinking their portion and don't have to pay a penalty just because other LSMs have a bigger space requirement. Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-02-14security: trim security.hAl Viro
Trim security.h Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: James Morris <jmorris@namei.org>
2012-01-06vfs: prefer ->dentry->d_sb to ->mnt->mnt_sbAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-11-11Smack: smackfs cipso seq read repairCasey Schaufler
Commit 272cd7a8c67dd40a31ecff76a503bbb84707f757 introduced a change to the way rule lists are handled and reported in the smackfs filesystem. One of the issues addressed had to do with the termination of read requests on /smack/load. This change introduced a error in /smack/cipso, which shares some of the same list processing code. This patch updates all the file access list handling in smackfs to use the code introduced for /smack/load. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-10-20Smack: allow to access /smack/access as normal userJarkko Sakkinen
Allow query access as a normal user removing the need for CAP_MAC_ADMIN. Give RW access to /smack/access for UGO. Do not import smack labels in access check. Signed-off-by: Jarkko Sakkinen <jarkko.j.sakkinen@gmail.com> Signed-off-by: Casey Schaufler <cschaufler@cschaufler-intel.(none)>
2011-10-18Smack: fix: invalid length set for the result of /smack/accessJarkko Sakkinen
Forgot to update simple_transaction_set() to take terminator character into account. Signed-off-by: Jarkko Sakkinen <jarkko.j.sakkinen@gmail.com> Signed-off-by: Casey Schaufler <cschaufler@cschaufler-intel.(none)>
2011-10-14Smack: compilation fixJarkko Sakkinen
On some build configurations PER_CLEAR_ON_SETID symbol was not found when compiling smack_lsm.c. This patch fixes the issue by explicitly doing #include <linux/personality.h>. Signed-off-by: Jarkko Sakkinen <jarkko.j.sakkinen@gmail.com> Signed-off-by: Casey Schaufler <cschaufler@cschaufler-intel.(none)>
2011-10-12Smack: fix for /smack/access output, use string instead of byteJarkko Sakkinen
Small fix for the output of access SmackFS file. Use string is instead of byte. Makes it easier to extend API if it is needed. Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
2011-10-12Smack: domain transition protections (v3)Jarkko Sakkinen
Protections for domain transition: - BPRM unsafe flags - Secureexec - Clear unsafe personality bits. - Clear parent death signal Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
2011-10-12Smack: Provide information for UDS getsockopt(SO_PEERCRED)Casey Schaufler
This patch is targeted for the smack-next tree. This patch takes advantage of the recent changes for performance and points the packet labels on UDS connect at the output label of the far side. This makes getsockopt(...SO_PEERCRED...) function properly. Without this change the getsockopt does not provide any information. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-10-12Smack: Clean up commentsCasey Schaufler
There are a number of comments in the Smack code that are either malformed or include code. This patch cleans them up. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-10-12Smack: Repair processing of fcntlCasey Schaufler
Al Viro pointed out that the processing of fcntl done by Smack appeared poorly designed. He was right. There are three things that required change. Most obviously, the list of commands that really imply writing is limited to those involving file locking and signal handling. The initialization if the file security blob was incomplete, requiring use of a heretofore unused LSM hook. Finally, the audit information coming from a helper masked the identity of the LSM hook. This patch corrects all three of these defects. This is targeted for the smack-next tree pending comments. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-10-12Smack: Rule list lookup performanceCasey Schaufler
This patch is targeted for the smack-next tree. Smack access checks suffer from two significant performance issues. In cases where there are large numbers of rules the search of the single list of rules is wasteful. Comparing the string values of the smack labels is less efficient than a numeric comparison would. These changes take advantage of the Smack label list, which maintains the mapping of Smack labels to secids and optional CIPSO labels. Because the labels are kept perpetually, an access check can be done strictly based on the address of the label in the list without ever looking at the label itself. Rather than keeping one global list of rules the rules with a particular subject label can be based off of that label list entry. The access check need never look at entries that do not use the current subject label. This requires that packets coming off the network with CIPSO direct Smack labels that have never been seen before be treated carefully. The only case where they could be delivered is where the receiving socket has an IPIN star label, so that case is explicitly addressed. On a system with 39,800 rules (200 labels in all permutations) a system with this patch runs an access speed test in 5% of the time of the old version. That should be a best case improvement. If all of the rules are associated with the same subject label and all of the accesses are for processes with that label (unlikely) the improvement is about 30%. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-10-12Smack: check permissions from user space (v2)Jarkko Sakkinen
Adds a new file into SmackFS called 'access'. Wanted Smack permission is written into /smack/access. After that result can be read from the opened file. If access applies result contains 1 and otherwise 0. File access is protected from race conditions by using simple_transaction_get()/set() API. Fixes from the previous version: - Removed smack.h changes, refactoring left-over from previous version. - Removed #include <linux/smack.h>, refactoring left-over from previous version. Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com> Signed-off-by: Casey Schaufler <cschaufler@cschaufler-intel.(none)>
2011-08-01doc: Update the email address for Paul Moore in various source filesPaul Moore
My @hp.com will no longer be valid starting August 5, 2011 so an update is necessary. My new email address is employer independent so we don't have to worry about doing this again any time soon. Signed-off-by: Paul Moore <paul.moore@hp.com> Signed-off-by: Paul Moore <paul@paul-moore.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-07-20->permission() sanitizing: don't pass flags to ->inode_permission()Al Viro
pass that via mask instead. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-05-24Merge branch 'master' of git://git.infradead.org/users/eparis/selinux into ↵James Morris
for-linus Conflicts: lib/flex_array.c security/selinux/avc.c security/selinux/hooks.c security/selinux/ss/policydb.c security/smack/smack_lsm.c Manually resolve conflicts. Signed-off-by: James Morris <jmorris@namei.org>
2011-04-25SMACK: smack_file_lock can use the struct pathEric Paris
smack_file_lock has a struct path, so use that instead of only the dentry. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com>
2011-04-25LSM: separate LSM_AUDIT_DATA_DENTRY from LSM_AUDIT_DATA_PATHEric Paris
This patch separates and audit message that only contains a dentry from one that contains a full path. This allows us to make it harder to misuse the interfaces or for the interfaces to be implemented wrong. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com>
2011-04-25LSM: split LSM_AUDIT_DATA_FS into _PATH and _INODEEric Paris
The lsm common audit code has wacky contortions making sure which pieces of information are set based on if it was given a path, dentry, or inode. Split this into path and inode to get rid of some of the code complexity. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com>
2011-04-25SECURITY: Move exec_permission RCU checks into security modulesAndi Kleen
Right now all RCU walks fall back to reference walk when CONFIG_SECURITY is enabled, even though just the standard capability module is active. This is because security_inode_exec_permission unconditionally fails RCU walks. Move this decision to the low level security module. This requires passing the RCU flags down the security hook. This way at least the capability module and a few easy cases in selinux/smack work with RCU walks with CONFIG_SECURITY=y Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Eric Paris <eparis@redhat.com>
2011-04-22SECURITY: Move exec_permission RCU checks into security modulesAndi Kleen
Right now all RCU walks fall back to reference walk when CONFIG_SECURITY is enabled, even though just the standard capability module is active. This is because security_inode_exec_permission unconditionally fails RCU walks. Move this decision to the low level security module. This requires passing the RCU flags down the security hook. This way at least the capability module and a few easy cases in selinux/smack work with RCU walks with CONFIG_SECURITY=y Signed-off-by: Andi Kleen <ak@linux.intel.com> Acked-by: Eric Paris <eparis@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-31Fix common misspellingsLucas De Marchi
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-08Merge branch 'master' of git://git.infradead.org/users/eparis/selinux into nextJames Morris
2011-02-09Smack: correct final mmap check comparisonCasey Schaufler
The mmap policy enforcement checks the access of the SMACK64MMAP subject against the current subject incorrectly. The check as written works correctly only if the access rules involved have the same access. This is the common case, so initial testing did not find a problem. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-02-09security:smack: kill unused SMACK_LIST_MAX, MAY_ANY and MAY_ANYWRITEShan Wei
Kill unused macros of SMACK_LIST_MAX, MAY_ANY and MAY_ANYWRITE. v2: As Casey Schaufler's advice, also remove MAY_ANY. Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-02-09Smack: correct behavior in the mmap hookCasey Schaufler
The mmap policy enforcement was not properly handling the interaction between the global and local rule lists. Instead of going through one and then the other, which missed the important case where a rule specified that there should be no access, combine the access limitations where there is a rule in each list. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: James Morris <jmorris@namei.org>
2011-02-01fs/vfs/security: pass last path component to LSM on inode creationEric Paris
SELinux would like to implement a new labeling behavior of newly created inodes. We currently label new inodes based on the parent and the creating process. This new behavior would also take into account the name of the new object when deciding the new label. This is not the (supposed) full path, just the last component of the path. This is very useful because creating /etc/shadow is different than creating /etc/passwd but the kernel hooks are unable to differentiate these operations. We currently require that userspace realize it is doing some difficult operation like that and than userspace jumps through SELinux hoops to get things set up correctly. This patch does not implement new behavior, that is obviously contained in a seperate SELinux patch, but it does pass the needed name down to the correct LSM hook. If no such name exists it is fine to pass NULL. Signed-off-by: Eric Paris <eparis@redhat.com>
2011-01-17Subject: [PATCH] Smack: mmap controls for library containmentCasey Schaufler
In the embedded world there are often situations where libraries are updated from a variety of sources, for a variety of reasons, and with any number of security characteristics. These differences might include privilege required for a given library provided interface to function properly, as occurs from time to time in graphics libraries. There are also cases where it is important to limit use of libraries based on the provider of the library and the security aware application may make choices based on that criteria. These issues are addressed by providing an additional Smack label that may optionally be assigned to an object, the SMACK64MMAP attribute. An mmap operation is allowed if there is no such attribute. If there is a SMACK64MMAP attribute the mmap is permitted only if a subject with that label has all of the access permitted a subject with the current task label. Security aware applications may from time to time wish to reduce their "privilege" to avoid accidental use of privilege. One case where this arises is the environment in which multiple sources provide libraries to perform the same functions. An application may know that it should eschew services made available from a particular vendor, or of a particular version. In support of this a secondary list of Smack rules has been added that is local to the task. This list is consulted only in the case where the global list has approved access. It can only further restrict access. Unlike the global last, if no entry is found on the local list access is granted. An application can add entries to its own list by writing to /smack/load-self. The changes appear large as they involve refactoring the list handling to accomodate there being more than one rule list. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-01-10Merge branch 'master' into nextJames Morris
Conflicts: security/smack/smack_lsm.c Verified and added fix by Stephen Rothwell <sfr@canb.auug.org.au> Ok'd by Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: James Morris <jmorris@namei.org>
2011-01-05af_unix: Avoid socket->sk NULL OOPS in stream connect security hooks.David S. Miller
unix_release() can asynchornously set socket->sk to NULL, and it does so without holding the unix_state_lock() on "other" during stream connects. However, the reverse mapping, sk->sk_socket, is only transitioned to NULL under the unix_state_lock(). Therefore make the security hooks follow the reverse mapping instead of the forward mapping. Reported-by: Jeremy Fitzhardinge <jeremy@goop.org> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-12-07Smack: Transmute labels on specified directoriesJarkko Sakkinen
In a situation where Smack access rules allow processes with multiple labels to write to a directory it is easy to get into a situation where the directory gets cluttered with files that the owner can't deal with because while they could be written to the directory a process at the label of the directory can't write them. This is generally the desired behavior, but when it isn't it is a real issue. This patch introduces a new attribute SMACK64TRANSMUTE that instructs Smack to create the file with the label of the directory under certain circumstances. A new access mode, "t" for transmute, is made available to Smack access rules, which are expanded from "rwxa" to "rwxat". If a file is created in a directory marked as transmutable and if access was granted to perform the operation by a rule that included the transmute mode, then the file gets the Smack label of the directory instead of the Smack label of the creating process. Note that this is equivalent to creating an empty file at the label of the directory and then having the other process write to it. The transmute scheme requires that both the access rule allows transmutation and that the directory be explicitly marked. Signed-off-by: Jarkko Sakkinen <ext-jarkko.2.sakkinen@nokia.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2010-12-02This patch adds a new security attribute to Smack calledCasey Schaufler
SMACK64EXEC. It defines label that is used while task is running. Exception: in smack_task_wait() child task is checked for write access to parent task using label inherited from the task that forked it. Fixed issues from previous submit: - SMACK64EXEC was not read when SMACK64 was not set. - inode security blob was not updated after setting SMACK64EXEC - inode security blob was not updated when removing SMACK64EXEC
2010-11-29Smack: UDS revisionCasey Schaufler
This patch addresses a number of long standing issues with the way Smack treats UNIX domain sockets. All access control was being done based on the label of the file system object. This is inconsistant with the internet domain, in which access is done based on the IPIN and IPOUT attributes of the socket. As a result of the inode label policy it was not possible to use a UDS socket for label cognizant services, including dbus and the X11 server. Support for SCM_PEERSEC on UDS sockets is also provided. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: James Morris <jmorris@namei.org>
2010-11-15capabilities/syslog: open code cap_syslog logic to fix build failureEric Paris
The addition of CONFIG_SECURITY_DMESG_RESTRICT resulted in a build failure when CONFIG_PRINTK=n. This is because the capabilities code which used the new option was built even though the variable in question didn't exist. The patch here fixes this by moving the capabilities checks out of the LSM and into the caller. All (known) LSMs should have been calling the capabilities hook already so it actually makes the code organization better to eliminate the hook altogether. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-29convert get_sb_single() usersAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-10-22Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bklLinus Torvalds
* 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl: vfs: make no_llseek the default vfs: don't use BKL in default_llseek llseek: automatically add .llseek fop libfs: use generic_file_llseek for simple_attr mac80211: disallow seeks in minstrel debug code lirc: make chardev nonseekable viotape: use noop_llseek raw: use explicit llseek file operations ibmasmfs: use generic_file_llseek spufs: use llseek in all file operations arm/omap: use generic_file_llseek in iommu_debug lkdtm: use generic_file_llseek in debugfs net/wireless: use generic_file_llseek in debugfs drm: use noop_llseek
2010-10-21security: secid_to_secctx returns len when data is NULLEric Paris
With the (long ago) interface change to have the secid_to_secctx functions do the string allocation instead of having the caller do the allocation we lost the ability to query the security server for the length of the upcoming string. The SECMARK code would like to allocate a netlink skb with enough length to hold the string but it is just too unclean to do the string allocation twice or to do the allocation the first time and hold onto the string and slen. This patch adds the ability to call security_secid_to_secctx() with a NULL data pointer and it will just set the slen pointer. Signed-off-by: Eric Paris <eparis@redhat.com> Reviewed-by: Paul Moore <paul.moore@hp.com> Signed-off-by: James Morris <jmorris@namei.org>
2010-10-21security: remove unused parameter from security_task_setscheduler()KOSAKI Motohiro
All security modules shouldn't change sched_param parameter of security_task_setscheduler(). This is not only meaningless, but also make a harmful result if caller pass a static variable. This patch remove policy and sched_param parameter from security_task_setscheduler() becuase none of security module is using it. Cc: James Morris <jmorris@namei.org> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: James Morris <jmorris@namei.org>
2010-10-15llseek: automatically add .llseek fopArnd Bergmann
All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>