From: John Johansen <john.johansen@canonical.com> To: Paul Moore <paul@paul-moore.com>, Stephen Smalley <sds@tycho.nsa.gov>, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org Cc: James Morris <james.l.morris@oracle.com>, serge@hallyn.com, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov Subject: Re: [PATCH] fs: switch order of CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH checks Date: Fri, 10 Mar 2017 13:12:14 -0800 [thread overview] Message-ID: <dba86213-43a5-cff2-0403-5dee971747e5@canonical.com> (raw) In-Reply-To: <CAHC9VhT42v2Z5hw8PSUqOtzhz1Ba3K4bL=DuSXTJwPberWtjLQ@mail.gmail.com> On 03/10/2017 11:54 AM, Paul Moore wrote: > On Fri, Mar 10, 2017 at 12:14 PM, Stephen Smalley <sds@tycho.nsa.gov> wrote: >> generic_permission() presently checks CAP_DAC_OVERRIDE prior to >> CAP_DAC_READ_SEARCH. This can cause misleading audit messages when >> using a LSM such as SELinux or AppArmor, since CAP_DAC_OVERRIDE >> may not be required for the operation. Flip the order of the >> tests so that CAP_DAC_OVERRIDE is only checked when required for >> the operation. >> >> Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> >> --- >> fs/namei.c | 20 ++++++++++---------- >> 1 file changed, 10 insertions(+), 10 deletions(-) > > This is the second posting of this patch and so far no comment ... if > I don't see any negative responses by next week I'll go ahead and > merge this into the selinux/next tree. > sounds good to me, the patch looks good you can have my acked-by for how this affects apparmor, or hrmm should that be a reviewed-by for the vfs end Acked-by: John Johansen <john.johansen@canonical.com> >> diff --git a/fs/namei.c b/fs/namei.c >> index d41fab7..482414a 100644 >> --- a/fs/namei.c >> +++ b/fs/namei.c >> @@ -340,22 +340,14 @@ int generic_permission(struct inode *inode, int mask) >> >> if (S_ISDIR(inode->i_mode)) { >> /* DACs are overridable for directories */ >> - if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) >> - return 0; >> if (!(mask & MAY_WRITE)) >> if (capable_wrt_inode_uidgid(inode, >> CAP_DAC_READ_SEARCH)) >> return 0; >> - return -EACCES; >> - } >> - /* >> - * Read/write DACs are always overridable. >> - * Executable DACs are overridable when there is >> - * at least one exec bit set. >> - */ >> - if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) >> if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) >> return 0; >> + return -EACCES; >> + } >> >> /* >> * Searching includes executable on directories, else just read. >> @@ -364,6 +356,14 @@ int generic_permission(struct inode *inode, int mask) >> if (mask == MAY_READ) >> if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) >> return 0; >> + /* >> + * Read/write DACs are always overridable. >> + * Executable DACs are overridable when there is >> + * at least one exec bit set. >> + */ >> + if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) >> + if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) >> + return 0; >> >> return -EACCES; >> } >> -- >> 2.7.4 >> > > >
WARNING: multiple messages have this Message-ID (diff)
From: john.johansen@canonical.com (John Johansen) To: linux-security-module@vger.kernel.org Subject: [PATCH] fs: switch order of CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH checks Date: Fri, 10 Mar 2017 13:12:14 -0800 [thread overview] Message-ID: <dba86213-43a5-cff2-0403-5dee971747e5@canonical.com> (raw) In-Reply-To: <CAHC9VhT42v2Z5hw8PSUqOtzhz1Ba3K4bL=DuSXTJwPberWtjLQ@mail.gmail.com> On 03/10/2017 11:54 AM, Paul Moore wrote: > On Fri, Mar 10, 2017 at 12:14 PM, Stephen Smalley <sds@tycho.nsa.gov> wrote: >> generic_permission() presently checks CAP_DAC_OVERRIDE prior to >> CAP_DAC_READ_SEARCH. This can cause misleading audit messages when >> using a LSM such as SELinux or AppArmor, since CAP_DAC_OVERRIDE >> may not be required for the operation. Flip the order of the >> tests so that CAP_DAC_OVERRIDE is only checked when required for >> the operation. >> >> Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> >> --- >> fs/namei.c | 20 ++++++++++---------- >> 1 file changed, 10 insertions(+), 10 deletions(-) > > This is the second posting of this patch and so far no comment ... if > I don't see any negative responses by next week I'll go ahead and > merge this into the selinux/next tree. > sounds good to me, the patch looks good you can have my acked-by for how this affects apparmor, or hrmm should that be a reviewed-by for the vfs end Acked-by: John Johansen <john.johansen@canonical.com> >> diff --git a/fs/namei.c b/fs/namei.c >> index d41fab7..482414a 100644 >> --- a/fs/namei.c >> +++ b/fs/namei.c >> @@ -340,22 +340,14 @@ int generic_permission(struct inode *inode, int mask) >> >> if (S_ISDIR(inode->i_mode)) { >> /* DACs are overridable for directories */ >> - if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) >> - return 0; >> if (!(mask & MAY_WRITE)) >> if (capable_wrt_inode_uidgid(inode, >> CAP_DAC_READ_SEARCH)) >> return 0; >> - return -EACCES; >> - } >> - /* >> - * Read/write DACs are always overridable. >> - * Executable DACs are overridable when there is >> - * at least one exec bit set. >> - */ >> - if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) >> if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) >> return 0; >> + return -EACCES; >> + } >> >> /* >> * Searching includes executable on directories, else just read. >> @@ -364,6 +356,14 @@ int generic_permission(struct inode *inode, int mask) >> if (mask == MAY_READ) >> if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) >> return 0; >> + /* >> + * Read/write DACs are always overridable. >> + * Executable DACs are overridable when there is >> + * at least one exec bit set. >> + */ >> + if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) >> + if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) >> + return 0; >> >> return -EACCES; >> } >> -- >> 2.7.4 >> > > > -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2017-03-10 21:12 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-03-10 17:14 [PATCH] fs: switch order of CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH checks Stephen Smalley 2017-03-10 17:14 ` Stephen Smalley 2017-03-10 19:54 ` Paul Moore 2017-03-10 19:54 ` Paul Moore 2017-03-10 21:12 ` John Johansen [this message] 2017-03-10 21:12 ` John Johansen 2017-03-29 21:36 ` Paul Moore 2017-03-29 21:36 ` Paul Moore 2017-03-10 21:47 ` Serge E. Hallyn 2017-03-10 21:47 ` Serge E. Hallyn 2017-03-11 1:05 ` James Morris 2017-03-11 1:05 ` James Morris -- strict thread matches above, loose matches on Subject: below -- 2017-02-17 18:24 Stephen Smalley
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