[PATCH 3/7] Add file_ns_capable() helper function for open-time capability checking
From: Wangyufen <hidden>
Date: 2014-07-18 02:21:36
Subsystem:
capabilities, the rest · Maintainers:
Serge Hallyn, Linus Torvalds
From: Wang Yufen <redacted> Nothing is using it yet, but this will allow us to delay the open-time checks to use time, without breaking the normal UNIX permission semantics where permissions are determined by the opener (and the file descriptor can then be passed to a different process, or the process can drop capabilities). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Wang Yufen <redacted> --- include/linux/capability.h | 3 ++- kernel/capability.c | 24 ++++++++++++++++++++++++ 2 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 12d52de..7273027 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h@@ -373,7 +373,7 @@ struct cpu_vfs_cap_data { #define CAP_TO_MASK(x) (1 << ((x) & 31)) /* mask for indexed __u32 */ #ifdef __KERNEL__ - +struct file; struct dentry; struct user_namespace;
@@ -548,6 +548,7 @@ extern bool has_ns_capability_noaudit(struct task_struct *t, extern bool capable(int cap); extern bool ns_capable(struct user_namespace *ns, int cap); extern bool nsown_capable(int cap); +extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap); /* audit system wants to get cap info from files as well */ extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
diff --git a/kernel/capability.c b/kernel/capability.c
index 3f1adb6..cc8c4845 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c@@ -393,6 +393,30 @@ bool ns_capable(struct user_namespace *ns, int cap) EXPORT_SYMBOL(ns_capable); /** + * file_ns_capable - Determine if the file's opener had a capability in effect + * @file: The file we want to check + * @ns: The usernamespace we want the capability in + * @cap: The capability to be tested for + * + * Return true if task that opened the file had a capability in effect + * when the file was opened. + * + * This does not set PF_SUPERPRIV because the caller may not + * actually be privileged. + */ +bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap) +{ + if (WARN_ON_ONCE(!cap_valid(cap))) + return false; + + if (security_capable(file->f_cred, ns, cap) == 0) + return true; + + return false; +} +EXPORT_SYMBOL(file_ns_capable); + +/** * capable - Determine if the current task has a superior capability in effect * @cap: The capability to be tested for *
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1.8.0