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| author | Jeff Vander Stoep <jeffv@google.com> | 2015-10-21 17:44:25 -0400 |
|---|---|---|
| committer | Paul Moore <pmoore@redhat.com> | 2015-10-21 17:44:25 -0400 |
| commit | 44d37ad3602b3823764eeb0f6c1ee3ef6c4fb936 (patch) | |
| tree | da06d34a35dc0364f8bec0276abcf796ffeeb81c | |
| parent | 2a35d196c160e352fa56eabb7952f78f4c85f577 (diff) | |
| download | lwn-44d37ad3602b3823764eeb0f6c1ee3ef6c4fb936.tar.gz lwn-44d37ad3602b3823764eeb0f6c1ee3ef6c4fb936.zip | |
selinux: do not check open perm on ftruncate call
Use the ATTR_FILE attribute to distinguish between truncate()
and ftruncate() system calls. The two other cases where
do_truncate is called with a filp (and therefore ATTR_FILE is set)
are for coredump files and for open(O_TRUNC). In both of those cases
the open permission has already been checked during file open and
therefore does not need to be repeated.
Commit 95dbf739313f ("SELinux: check OPEN on truncate calls")
fixed a major issue where domains were allowed to truncate files
without the open permission. However, it introduced a new bug where
a domain with the write permission can no longer ftruncate files
without the open permission, even when they receive an already open
file.
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <pmoore@redhat.com>
| -rw-r--r-- | security/selinux/hooks.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index e4369d86e588..7cd71cea0503 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2946,7 +2946,8 @@ static int selinux_inode_setattr(struct dentry *dentry, struct iattr *iattr) ATTR_ATIME_SET | ATTR_MTIME_SET | ATTR_TIMES_SET)) return dentry_has_perm(cred, dentry, FILE__SETATTR); - if (selinux_policycap_openperm && (ia_valid & ATTR_SIZE)) + if (selinux_policycap_openperm && (ia_valid & ATTR_SIZE) + && !(ia_valid & ATTR_FILE)) av |= FILE__OPEN; return dentry_has_perm(cred, dentry, av); |