path: root/security/smack
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authorStephen Smalley <sds@tycho.nsa.gov>2008-05-19 08:32:49 -0400
committerJames Morris <jmorris@namei.org>2008-07-14 15:01:47 +1000
commit006ebb40d3d65338bd74abb03b945f8d60e362bd (patch)
treec548c678b54b307e1fb9acf94676fb7bfd849501 /security/smack
parentfeb2a5b82d87fbdc01c00b7e9413e4b5f4c1f0c1 (diff)
Security: split proc ptrace checking into read vs. attach
Enable security modules to distinguish reading of process state via proc from full ptrace access by renaming ptrace_may_attach to ptrace_may_access and adding a mode argument indicating whether only read access or full attach access is requested. This allows security modules to permit access to reading process state without granting full ptrace access. The base DAC/capability checking remains unchanged. Read access to /proc/pid/mem continues to apply a full ptrace attach check since check_mem_permission() already requires the current task to already be ptracing the target. The other ptrace checks within proc for elements like environ, maps, and fds are changed to pass the read mode instead of attach. In the SELinux case, we model such reading of process state as a reading of a proc file labeled with the target process' label. This enables SELinux policy to permit such reading of process state without permitting control or manipulation of the target process, as there are a number of cases where programs probe for such information via proc but do not need to be able to control the target (e.g. procps, lsof, PolicyKit, ConsoleKit). At present we have to choose between allowing full ptrace in policy (more permissive than required/desired) or breaking functionality (or in some cases just silencing the denials via dontaudit rules but this can hide genuine attacks). This version of the patch incorporates comments from Casey Schaufler (change/replace existing ptrace_may_attach interface, pass access mode), and Chris Wright (provide greater consistency in the checking). Note that like their predecessors __ptrace_may_attach and ptrace_may_attach, the __ptrace_may_access and ptrace_may_access interfaces use different return value conventions from each other (0 or -errno vs. 1 or 0). I retained this difference to avoid any changes to the caller logic but made the difference clearer by changing the latter interface to return a bool rather than an int and by adding a comment about it to ptrace.h for any future callers. Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'security/smack')
1 files changed, 3 insertions, 2 deletions
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 4a09293efa0..3c7150b3493 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -95,11 +95,12 @@ struct inode_smack *new_inode_smack(char *smack)
* Do the capability checks, and require read and write.
-static int smack_ptrace(struct task_struct *ptp, struct task_struct *ctp)
+static int smack_ptrace(struct task_struct *ptp, struct task_struct *ctp,
+ unsigned int mode)
int rc;
- rc = cap_ptrace(ptp, ctp);
+ rc = cap_ptrace(ptp, ctp, mode);
if (rc != 0)
return rc;