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| author | Serge E. Hallyn <serge@hallyn.com> | 2010-12-08 15:19:01 +0000 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2010-12-09 09:48:48 +1100 |
| commit | 38ef4c2e437d11b5922723504b62824e96761459 (patch) | |
| tree | ccec1f38348af3c2776fc5bc0b589e14504f4b33 | |
| parent | 5c6d1125f8dbd1bfef39e38fbc2837003be78a59 (diff) | |
| download | linux-stable-38ef4c2e437d11b5922723504b62824e96761459.tar.gz linux-stable-38ef4c2e437d11b5922723504b62824e96761459.tar.bz2 linux-stable-38ef4c2e437d11b5922723504b62824e96761459.zip | |
syslog: check cap_syslog when dmesg_restrict
Eric Paris pointed out that it doesn't make sense to require
both CAP_SYS_ADMIN and CAP_SYSLOG for certain syslog actions.
So require CAP_SYSLOG, not CAP_SYS_ADMIN, when dmesg_restrict
is set.
(I'm also consolidating the now common error path)
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: Kees Cook <kees.cook@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>
| -rw-r--r-- | Documentation/sysctl/kernel.txt | 2 | ||||
| -rw-r--r-- | kernel/printk.c | 20 |
2 files changed, 11 insertions, 11 deletions
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index 209e1584c3dc..574067194f38 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -219,7 +219,7 @@ dmesg_restrict: This toggle indicates whether unprivileged users are prevented from using dmesg(8) to view messages from the kernel's log buffer. When dmesg_restrict is set to (0) there are no restrictions. When -dmesg_restrict is set set to (1), users must have CAP_SYS_ADMIN to use +dmesg_restrict is set set to (1), users must have CAP_SYSLOG to use dmesg(8). The kernel config option CONFIG_SECURITY_DMESG_RESTRICT sets the default diff --git a/kernel/printk.c b/kernel/printk.c index 0712380737b3..0cecba059666 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -279,18 +279,12 @@ int do_syslog(int type, char __user *buf, int len, bool from_file) * at open time. */ if (type == SYSLOG_ACTION_OPEN || !from_file) { - if (dmesg_restrict && !capable(CAP_SYS_ADMIN)) - return -EPERM; + if (dmesg_restrict && !capable(CAP_SYSLOG)) + goto warn; /* switch to return -EPERM after 2.6.39 */ if ((type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER) && - !capable(CAP_SYSLOG)) { - /* remove after 2.6.38 */ - if (capable(CAP_SYS_ADMIN)) - WARN_ONCE(1, "Attempt to access syslog with " - "CAP_SYS_ADMIN but no CAP_SYSLOG " - "(deprecated and denied).\n"); - return -EPERM; - } + !capable(CAP_SYSLOG)) + goto warn; /* switch to return -EPERM after 2.6.39 */ } error = security_syslog(type); @@ -434,6 +428,12 @@ int do_syslog(int type, char __user *buf, int len, bool from_file) } out: return error; +warn: + /* remove after 2.6.39 */ + if (capable(CAP_SYS_ADMIN)) + WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN " + "but no CAP_SYSLOG (deprecated and denied).\n"); + return -EPERM; } SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |