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cgroup-v1: Require capabilities to set release_agent
The cgroup release_agent is called with call_usermodehelper. The function
call_usermodehelper starts the release_agent with a full set fo capabilities.
Therefore require capabilities when setting the release_agaent.
Reported-by: Tabitha Sable <tabitha.c.sable@gmail.com>
Tested-by: Tabitha Sable <tabitha.c.sable@gmail.com>
Fixes: 81a6a5cdd2
("Task Control Groups: automatic userspace notification of idle cgroups")
Cc: stable@vger.kernel.org # v2.6.24+
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
parent
c80d401c52
commit
24f6008564
@ -549,6 +549,14 @@ static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
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BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
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/*
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* Release agent gets called with all capabilities,
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* require capabilities to set release agent.
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*/
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if ((of->file->f_cred->user_ns != &init_user_ns) ||
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!capable(CAP_SYS_ADMIN))
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return -EPERM;
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cgrp = cgroup_kn_lock_live(of->kn, false);
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if (!cgrp)
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return -ENODEV;
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@ -954,6 +962,12 @@ int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
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/* Specifying two release agents is forbidden */
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if (ctx->release_agent)
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return invalfc(fc, "release_agent respecified");
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/*
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* Release agent gets called with all capabilities,
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* require capabilities to set release agent.
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*/
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if ((fc->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN))
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return invalfc(fc, "Setting release_agent not allowed");
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ctx->release_agent = param->string;
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param->string = NULL;
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break;
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