linux-dev - Linux kernel development work

Age	Commit message (Collapse)	Author	Files	Lines
2007-10-18	V3 file capabilities: alter behavior of cap_setpcap	Andrew Morgan	1	-0/+5
	The non-filesystem capability meaning of CAP_SETPCAP is that a process, p1, can change the capabilities of another process, p2. This is not the meaning that was intended for this capability at all, and this implementation came about purely because, without filesystem capabilities, there was no way to use capabilities without one process bestowing them on another. Since we now have a filesystem support for capabilities we can fix the implementation of CAP_SETPCAP. The most significant thing about this change is that, with it in effect, no process can set the capabilities of another process. The capabilities of a program are set via the capability convolution rules: pI(post-exec) = pI(pre-exec) pP(post-exec) = (X(aka cap_bset) & fP) \| (pI(post-exec) & fI) pE(post-exec) = fE ? pP(post-exec) : 0 at exec() time. As such, the only influence the pre-exec() program can have on the post-exec() program's capabilities are through the pI capability set. The correct implementation for CAP_SETPCAP (and that enabled by this patch) is that it can be used to add extra pI capabilities to the current process - to be picked up by subsequent exec()s when the above convolution rules are applied. Here is how it works: Let's say we have a process, p. It has capability sets, pE, pP and pI. Generally, p, can change the value of its own pI to pI' where (pI' & ~pI) & ~pP = 0. That is, the only new things in pI' that were not present in pI need to be present in pP. The role of CAP_SETPCAP is basically to permit changes to pI beyond the above: if (pE & CAP_SETPCAP) { pI' = anything; /* ie., even (pI' & ~pI) & ~pP != 0 */ } This capability is useful for things like login, which (say, via pam_cap) might want to raise certain inheritable capabilities for use by the children of the logged-in user's shell, but those capabilities are not useful to or needed by the login program itself. One such use might be to limit who can run ping. You set the capabilities of the 'ping' program to be "= cap_net_raw+i", and then only shells that have (pI & CAP_NET_RAW) will be able to run it. Without CAP_SETPCAP implemented as described above, login(pam_cap) would have to also have (pP & CAP_NET_RAW) in order to raise this capability and pass it on through the inheritable set. Signed-off-by: Andrew Morgan <morgan@kernel.org> Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-18	sysctl: for irda update sysctl_checks list of binary paths	Eric W. Biederman	1	-0/+19
	It turns out that the net/irda code didn't register any of it's binary paths in the global sysctl.h header file so I missed them completely when making an authoritative list of binary sysctl paths in the kernel. So add them to the list of valid binary sysctl paths. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Samuel Ortiz <samuel@sortiz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-18	sysctl: update sysctl_check_table	Eric W. Biederman	1	-14/+22
	Well it turns out after I dug into the problems a little more I was returning a few false positives so this patch updates my logic to remove them. - Don't complain about 0 ctl_names in sysctl_check_binary_path It is valid for someone to remove the sysctl binary interface and still keep the same sysctl proc interface. - Count ctl_names and procnames as matching if they both don't exist. - Only warn about missing min&max when the generic functions care. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@sw.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-18	sysctl: Error on bad sysctl tables	Eric W. Biederman	1	-0/+1556
	After going through the kernels sysctl tables several times it has become clear that code review and testing is just not effective in prevent problematic sysctl tables from being used in the stable kernel. I certainly can't seem to fix the problems as fast as they are introduced. Therefore this patch adds sysctl_check_table which is called when a sysctl table is registered and checks to see if we have a problematic sysctl table. The biggest part of the code is the table of valid binary sysctl entries, but since we have frozen our set of binary sysctls this table should not need to change, and it makes it much easier to detect when someone unintentionally adds a new binary sysctl value. As best as I can determine all of the several hundred errors spewed on boot up now are legitimate. [bunk@kernel.org: kernel/sysctl_check.c must #include <linux/string.h>] Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@sw.ru> Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>