diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/printk.c | 54 |
1 files changed, 35 insertions, 19 deletions
diff --git a/kernel/printk.c b/kernel/printk.c index 2ddbdc73aad..36231525e22 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -262,25 +262,47 @@ int dmesg_restrict = 1; int dmesg_restrict; #endif +static int syslog_action_restricted(int type) +{ + if (dmesg_restrict) + return 1; + /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ + return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; +} + +static int check_syslog_permissions(int type, bool from_file) +{ + /* + * If this is from /proc/kmsg and we've already opened it, then we've + * already done the capabilities checks at open time. + */ + if (from_file && type != SYSLOG_ACTION_OPEN) + return 0; + + if (syslog_action_restricted(type)) { + if (capable(CAP_SYSLOG)) + return 0; + /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ + if (capable(CAP_SYS_ADMIN)) { + WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN " + "but no CAP_SYSLOG (deprecated).\n"); + return 0; + } + return -EPERM; + } + return 0; +} + int do_syslog(int type, char __user *buf, int len, bool from_file) { unsigned i, j, limit, count; int do_clear = 0; char c; - int error = 0; + int error; - /* - * If this is from /proc/kmsg we only do the capabilities checks - * at open time. - */ - if (type == SYSLOG_ACTION_OPEN || !from_file) { - 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)) - goto warn; /* switch to return -EPERM after 2.6.39 */ - } + error = check_syslog_permissions(type, from_file); + if (error) + goto out; error = security_syslog(type); if (error) @@ -423,12 +445,6 @@ 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) |