path: root/security
diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2011-06-08 15:11:56 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-06-08 15:11:56 -0700
commit95f4efb2d78661065aaf0be57f5bf00e4d2aea1d (patch)
treee344402e6428194515a0550ef30cf7cb8eeb0fdf /security
parent4c1f683a4a343808536a5617ede85dfc34430472 (diff)
selinux: simplify and clean up inode_has_perm()
This is a rather hot function that is called with a potentially NULL "struct common_audit_data" pointer argument. And in that case it has to provide and initialize its own dummy common_audit_data structure. However, all the _common_ cases already pass it a real audit-data structure, so that uncommon NULL case not only creates a silly run-time test, more importantly it causes that function to have a big stack frame for the dummy variable that isn't even used in the common case! So get rid of that stupid run-time behavior, and make the (few) functions that currently call with a NULL pointer just call a new helper function instead (naturally called inode_has_perm_noapd(), since it has no adp argument). This makes the run-time test be a static code generation issue instead, and allows for a much denser stack since none of the common callers need the dummy structure. And a denser stack not only means less stack space usage, it means better cache behavior. So we have a win-win-win from this simplification: less code executed, smaller stack footprint, and better cache behavior. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security')
1 files changed, 15 insertions, 10 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index a0d38459d65..20219ef5439 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1476,7 +1476,6 @@ static int inode_has_perm(const struct cred *cred,
unsigned flags)
struct inode_security_struct *isec;
- struct common_audit_data ad;
u32 sid;
@@ -1487,15 +1486,21 @@ static int inode_has_perm(const struct cred *cred,
sid = cred_sid(cred);
isec = inode->i_security;
- if (!adp) {
- adp = &ad;
- ad.u.inode = inode;
- }
return avc_has_perm_flags(sid, isec->sid, isec->sclass, perms, adp, flags);
+static int inode_has_perm_noadp(const struct cred *cred,
+ struct inode *inode,
+ u32 perms,
+ unsigned flags)
+ struct common_audit_data ad;
+ ad.u.inode = inode;
+ return inode_has_perm(cred, inode, perms, &ad, flags);
/* Same as inode_has_perm, but pass explicit audit data containing
the dentry to help the auditing code to more easily generate the
pathname if needed. */
@@ -2122,8 +2127,8 @@ static inline void flush_unauthorized_files(const struct cred *cred,
struct tty_file_private, list);
file = file_priv->file;
inode = file->f_path.dentry->d_inode;
- if (inode_has_perm(cred, inode,
+ if (inode_has_perm_noadp(cred, inode,
drop_tty = 1;
@@ -3228,7 +3233,7 @@ static int selinux_dentry_open(struct file *file, const struct cred *cred)
* new inode label or new policy.
* This check is not redundant - do not remove.
- return inode_has_perm(cred, inode, open_file_to_av(file), NULL, 0);
+ return inode_has_perm_noadp(cred, inode, open_file_to_av(file), 0);
/* task security operations */